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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Jul 04 2024 Valid 041630Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND THE SOUTHERN PLAINS TO OHIO VALLEY... ...SUMMARY... Scattered severe thunderstorms will be possible this afternoon and evening across parts of the upper Mississippi Valley, and from the southern Plains to the lower Ohio Valley. ...Synopsis... An upper trough over the northern/central Plains will move generally eastward today across the Upper Midwest and mid MS Valley. A separate, convectively augmented mid-level vorticity maximum is present over southern IA/northern MO late this morning. This MCV and associated convection across the OH Valley will move east-northeastward across the OH Valley/Midwest through this evening. At the surface, a weak low should develop eastward across parts of the Upper Midwest in tandem with the large-scale upper trough. Another weak surface low should also track northeastward over the OH Valley with the remnant MCV. A convectively reinforced front draped from the southern Plains northeastward into the mid MS and OH Valleys will likely serve as a focus for strong to severe thunderstorms this afternoon and evening. ...Mid Mississippi Valley into the Ohio Valley and Mid-Atlantic... Mostly elevated thunderstorms are ongoing late this morning across the lower OH Valley. The rather moist low-level airmass along/south of a front will continue to gradually destabilize through the afternoon. Although mid-level lapse rates will remain poor, moderate instability has already developed downstream of activity moving across southern IN and western KY. Additional intensification of this convection will probably occur through early afternoon across parts of central/eastern KY and perhaps southern OH ahead of the MCV. Even though stronger mid-level flow may tend to remain displaced to the north of the front, modest but sufficient deep-layer shear should be present to support multicell clustering. Scattered damaging winds occasionally reaching severe thresholds should be the main threat with this activity as it spreads eastward across the lower OH Valley this afternoon and evening. Low-level flow is forecast to remain generally modest and veered to southwesterly. Still, sufficient speed shear will be present to support some threat for updraft rotation and perhaps a tornado or two, especially if any supercells can develop and persist. Isolated hail may also occur with more robust cores. Confidence in strong convection moving off the Blue Ridge Mountains in the Mid-Atlantic is relatively low. But, any thunderstorms that do form across this region could produce locally damaging winds. ...Southern Plains to the Ozarks... The portion of the cold front extending across the southern Plains into the Ozarks is forecast to make only slow southward progress through this evening. Even with some mid/high-level clouds persisting across these areas, robust daytime heating along/south of the front will likely encourage surface temperatures to warm into the 90s and low 100s. Even though low/mid-level flow will remain fairly weak, rather large surface temperature/dewpoint spreads (up to 30-40 degrees F) and steepened low-level lapse rates should foster a threat for mainly severe/damaging winds with any thunderstorms that can develop this afternoon and evening. Robust convection appears probable along/near the front by 22-00Z, and there appears to be some potential for an organized cluster to develop over the Ozarks/southern MO vicinity and sweep east-southeastward through the late evening. ...Upper Mississippi Valley... A focused area of ascent associated with the upper trough will overspread southern MN and northern IA today. While cloud cover remains prevalent over much of this region late this morning, there has been some recent clearing on the western edge of the cloud deck. A relatively small area of modest destabilization is still anticipated, with MLCAPE around 1000-1500 J/kg possible. A 45-60 kt mid-level jet attendant to the upper trough will overspread the developing warm sector through the afternoon. This jet will aid sufficiently strong deep-layer shear to support supercells with an associated threat for severe hail. Some clustering/upscale growth may eventually occur, which would support a greater threat for severe/damaging winds. This activity should weaken by late evening into WI and northern IL as it encounters a less unstable airmass. ..Gleason/Thornton.. 07/04/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Jul 04 2024 Valid 041630Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND THE SOUTHERN PLAINS TO OHIO VALLEY... ...SUMMARY... Scattered severe thunderstorms will be possible this afternoon and evening across parts of the upper Mississippi Valley, and from the southern Plains to the lower Ohio Valley. ...Synopsis... An upper trough over the northern/central Plains will move generally eastward today across the Upper Midwest and mid MS Valley. A separate, convectively augmented mid-level vorticity maximum is present over southern IA/northern MO late this morning. This MCV and associated convection across the OH Valley will move east-northeastward across the OH Valley/Midwest through this evening. At the surface, a weak low should develop eastward across parts of the Upper Midwest in tandem with the large-scale upper trough. Another weak surface low should also track northeastward over the OH Valley with the remnant MCV. A convectively reinforced front draped from the southern Plains northeastward into the mid MS and OH Valleys will likely serve as a focus for strong to severe thunderstorms this afternoon and evening. ...Mid Mississippi Valley into the Ohio Valley and Mid-Atlantic... Mostly elevated thunderstorms are ongoing late this morning across the lower OH Valley. The rather moist low-level airmass along/south of a front will continue to gradually destabilize through the afternoon. Although mid-level lapse rates will remain poor, moderate instability has already developed downstream of activity moving across southern IN and western KY. Additional intensification of this convection will probably occur through early afternoon across parts of central/eastern KY and perhaps southern OH ahead of the MCV. Even though stronger mid-level flow may tend to remain displaced to the north of the front, modest but sufficient deep-layer shear should be present to support multicell clustering. Scattered damaging winds occasionally reaching severe thresholds should be the main threat with this activity as it spreads eastward across the lower OH Valley this afternoon and evening. Low-level flow is forecast to remain generally modest and veered to southwesterly. Still, sufficient speed shear will be present to support some threat for updraft rotation and perhaps a tornado or two, especially if any supercells can develop and persist. Isolated hail may also occur with more robust cores. Confidence in strong convection moving off the Blue Ridge Mountains in the Mid-Atlantic is relatively low. But, any thunderstorms that do form across this region could produce locally damaging winds. ...Southern Plains to the Ozarks... The portion of the cold front extending across the southern Plains into the Ozarks is forecast to make only slow southward progress through this evening. Even with some mid/high-level clouds persisting across these areas, robust daytime heating along/south of the front will likely encourage surface temperatures to warm into the 90s and low 100s. Even though low/mid-level flow will remain fairly weak, rather large surface temperature/dewpoint spreads (up to 30-40 degrees F) and steepened low-level lapse rates should foster a threat for mainly severe/damaging winds with any thunderstorms that can develop this afternoon and evening. Robust convection appears probable along/near the front by 22-00Z, and there appears to be some potential for an organized cluster to develop over the Ozarks/southern MO vicinity and sweep east-southeastward through the late evening. ...Upper Mississippi Valley... A focused area of ascent associated with the upper trough will overspread southern MN and northern IA today. While cloud cover remains prevalent over much of this region late this morning, there has been some recent clearing on the western edge of the cloud deck. A relatively small area of modest destabilization is still anticipated, with MLCAPE around 1000-1500 J/kg possible. A 45-60 kt mid-level jet attendant to the upper trough will overspread the developing warm sector through the afternoon. This jet will aid sufficiently strong deep-layer shear to support supercells with an associated threat for severe hail. Some clustering/upscale growth may eventually occur, which would support a greater threat for severe/damaging winds. This activity should weaken by late evening into WI and northern IL as it encounters a less unstable airmass. ..Gleason/Thornton.. 07/04/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Thu Jul 04 2024 Valid 041630Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND THE SOUTHERN PLAINS TO OHIO VALLEY... ...SUMMARY... Scattered severe thunderstorms will be possible this afternoon and evening across parts of the upper Mississippi Valley, and from the southern Plains to the lower Ohio Valley. ...Synopsis... An upper trough over the northern/central Plains will move generally eastward today across the Upper Midwest and mid MS Valley. A separate, convectively augmented mid-level vorticity maximum is present over southern IA/northern MO late this morning. This MCV and associated convection across the OH Valley will move east-northeastward across the OH Valley/Midwest through this evening. At the surface, a weak low should develop eastward across parts of the Upper Midwest in tandem with the large-scale upper trough. Another weak surface low should also track northeastward over the OH Valley with the remnant MCV. A convectively reinforced front draped from the southern Plains northeastward into the mid MS and OH Valleys will likely serve as a focus for strong to severe thunderstorms this afternoon and evening. ...Mid Mississippi Valley into the Ohio Valley and Mid-Atlantic... Mostly elevated thunderstorms are ongoing late this morning across the lower OH Valley. The rather moist low-level airmass along/south of a front will continue to gradually destabilize through the afternoon. Although mid-level lapse rates will remain poor, moderate instability has already developed downstream of activity moving across southern IN and western KY. Additional intensification of this convection will probably occur through early afternoon across parts of central/eastern KY and perhaps southern OH ahead of the MCV. Even though stronger mid-level flow may tend to remain displaced to the north of the front, modest but sufficient deep-layer shear should be present to support multicell clustering. Scattered damaging winds occasionally reaching severe thresholds should be the main threat with this activity as it spreads eastward across the lower OH Valley this afternoon and evening. Low-level flow is forecast to remain generally modest and veered to southwesterly. Still, sufficient speed shear will be present to support some threat for updraft rotation and perhaps a tornado or two, especially if any supercells can develop and persist. Isolated hail may also occur with more robust cores. Confidence in strong convection moving off the Blue Ridge Mountains in the Mid-Atlantic is relatively low. But, any thunderstorms that do form across this region could produce locally damaging winds. ...Southern Plains to the Ozarks... The portion of the cold front extending across the southern Plains into the Ozarks is forecast to make only slow southward progress through this evening. Even with some mid/high-level clouds persisting across these areas, robust daytime heating along/south of the front will likely encourage surface temperatures to warm into the 90s and low 100s. Even though low/mid-level flow will remain fairly weak, rather large surface temperature/dewpoint spreads (up to 30-40 degrees F) and steepened low-level lapse rates should foster a threat for mainly severe/damaging winds with any thunderstorms that can develop this afternoon and evening. Robust convection appears probable along/near the front by 22-00Z, and there appears to be some potential for an organized cluster to develop over the Ozarks/southern MO vicinity and sweep east-southeastward through the late evening. ...Upper Mississippi Valley... A focused area of ascent associated with the upper trough will overspread southern MN and northern IA today. While cloud cover remains prevalent over much of this region late this morning, there has been some recent clearing on the western edge of the cloud deck. A relatively small area of modest destabilization is still anticipated, with MLCAPE around 1000-1500 J/kg possible. A 45-60 kt mid-level jet attendant to the upper trough will overspread the developing warm sector through the afternoon. This jet will aid sufficiently strong deep-layer shear to support supercells with an associated threat for severe hail. Some clustering/upscale growth may eventually occur, which would support a greater threat for severe/damaging winds. This activity should weaken by late evening into WI and northern IL as it encounters a less unstable airmass. ..Gleason/Thornton.. 07/04/2024 Read more

5-Day Uncertainty Track last updated Thu, 04 Jul 2024 14:50:24 GMT


Wind Speed Probabilities last updated Thu, 04 Jul 2024 15:29:12 GMT

Issued at 900 AM CST Thu Jul 04 2024 312 WTPZ41 KNHC 041449 TCDEP1 Tropical Depression One-E Discussion Number 1 NWS National Hurricane Center Miami FL EP012024 900 AM CST Thu Jul 04 2024 Showers and thunderstorms have become better organized over the past 12-18 hours in association with the small area of low pressure that NHC has been monitoring for the past several days. There have been no recent scatterometer or passive microwave passes to assess the low-level circulation of the system. However, the persistence of the convection and the current satellite structure suggest a well-defined surface circulation has likely formed underneath the colder cloud tops. It is determined that the first tropical depression of the eastern Pacific season has formed. The initial intensity is set at 30 kt based on a T2.0 subjective Dvorak classification from TAFB. The center position of the depression is uncertain based on the lack of data, but the initial estimated motion is northwest (325/8 kt). The models agree that this motion will continue into tonight, followed by a westward turn on Friday within the low-level flow. With warm SSTs and relatively low shear today, it is possible that the system could briefly strengthen into a tropical storm, though not explicitly forecast. The tropical cyclone will move across the 26C isotherm during the next 24-36 h, and the cooler waters and drier mid-level environment thereafter should induce a weakening trend. In fact, the GFS and ECMWF model-simulated satellite imagery suggest convection is likely to collapse on Friday, and the system is forecast to become a remnant low by Friday night and dissipate later this weekend. FORECAST POSITIONS AND MAX WINDS INIT 04/1500Z 17.0N 105.9W 30 KT 35 MPH 12H 05/0000Z 17.7N 107.0W 30 KT 35 MPH 24H 05/1200Z 17.8N 108.6W 25 KT 30 MPH 36H 06/0000Z 17.5N 109.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 06/1200Z 17.0N 111.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 60H 07/0000Z...DISSIPATED $$ Forecaster Reinhart

Issued at 1500 UTC THU JUL 04 2024 896 FOPZ11 KNHC 041448 PWSEP1 TROPICAL DEPRESSION ONE-E WIND SPEED PROBABILITIES NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012024 1500 UTC THU JUL 04 2024 AT 1500Z THE CENTER OF TROPICAL DEPRESSION ONE-E WAS LOCATED NEAR LATITUDE 17.0 NORTH...LONGITUDE 105.9 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 30 KTS...35 MPH...55 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) PACIFIC DAYLIGHT TIME (PDT)...SUBTRACT 7 HOURS FROM Z TIME HAWAIIAN STANDARD TIME (HST)...SUBTRACT 10 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 12Z THU AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 12Z THU 00Z FRI 12Z FRI 00Z SAT 12Z SAT 12Z SUN 12Z MON PERIODS TO TO TO TO TO TO TO 00Z FRI 12Z FRI 00Z SAT 12Z SAT 12Z SUN 12Z MON 12Z TUE FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT ISLA SOCORRO 34 X X( X) 2( 2) 1( 3) X( 3) X( 3) X( 3) $$ FORECASTER REINHART

Issued at 900 AM CST Thu Jul 04 2024 201 WTPZ31 KNHC 041448 TCPEP1 BULLETIN Tropical Depression One-E Advisory Number 1 NWS National Hurricane Center Miami FL EP012024 900 AM CST Thu Jul 04 2024 ...FIRST TROPICAL DEPRESSION OF THE EASTERN PACIFIC SEASON FORMS... ...EXPECTED TO BE A SHORT-LIVED SYSTEM... SUMMARY OF 900 AM CST...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...17.0N 105.9W ABOUT 175 MI...280 KM SW OF MANZANILLO MEXICO MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...NW OR 325 DEGREES AT 9 MPH...15 KM/H MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 900 AM CST (1500 UTC), the center of Tropical Depression One-E was located near latitude 17.0 North, longitude 105.9 West. The depression is moving toward the northwest near 9 mph (15 km/h), and this general motion is expected to continue through tonight. A turn toward the west is forecast on Friday and Friday night. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Little change in strength is forecast today, followed by gradual weakening tonight and Friday. The system is forecast to become a remnant low by Friday night. The estimated minimum central pressure is 1007 mb (29.74 inches). HAZARDS AFFECTING LAND ---------------------- None. NEXT ADVISORY ------------- Next complete advisory at 300 PM CST. $$ Forecaster Reinhart

...FIRST TROPICAL DEPRESSION OF THE EASTERN PACIFIC SEASON FORMS... ...EXPECTED TO BE A SHORT-LIVED SYSTEM... As of 9:00 AM CST Thu Jul 4 the center of One-E was located near 17.0, -105.9 with movement NW at 9 mph. The minimum central pressure was 1007 mb with maximum sustained winds of about 35 mph.

Issued at 1500 UTC THU JUL 04 2024 000 WTPZ21 KNHC 041448 TCMEP1 TROPICAL DEPRESSION ONE-E FORECAST/ADVISORY NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012024 1500 UTC THU JUL 04 2024 TROPICAL DEPRESSION CENTER LOCATED NEAR 17.0N 105.9W AT 04/1500Z POSITION ACCURATE WITHIN 45 NM PRESENT MOVEMENT TOWARD THE NORTHWEST OR 325 DEGREES AT 8 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1007 MB MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 17.0N 105.9W AT 04/1500Z AT 04/1200Z CENTER WAS LOCATED NEAR 16.8N 105.5W FORECAST VALID 05/0000Z 17.7N 107.0W MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 05/1200Z 17.8N 108.6W MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 06/0000Z 17.5N 109.9W...POST-TROP/REMNT LOW MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 06/1200Z 17.0N 111.5W...POST-TROP/REMNT LOW MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 07/0000Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 17.0N 105.9W NEXT ADVISORY AT 04/2100Z $$ FORECASTER REINHART

987
ABPZ20 KNHC 041351
TWOEP

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
650 AM PDT Thu Jul 4 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Special outlook issued to raise probabilities and update discussion
of the disturbance offshore of southwestern Mexico.

Offshore of Southwestern Mexico (EP91):
Early visible satellite images indicate that shower and thunderstorm
activity continues to become better organized in association with an
area of low pressure located a couple of hundred miles offshore of
the southwestern coast of Mexico. Additionally, the circulation of
the system appears to have become better defined since yesterday. If
these development trends continue, advisories will likely be
initiated on this system as a tropical depression this morning. The
system is forecast to move northwestward through tonight and then
turn westward on Friday, remaining offshore of the southwestern
coast of Mexico.
* Formation chance through 48 hours...high....80 percent.
* Formation chance through 7 days...high...80 percent.

$$
Forecaster Reinhart

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Thu Jul 04 2024 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY...AND LOWER OHIO VALLEY TO SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms will be possible across parts of the upper Mississippi Valley, and lower Ohio Valley to southern Plains. ...Synopsis... In mid/upper levels, strengthening ridging over the Pacific Coast will result in height rises over much of the Northwest, while the subtropical ridge weakens slightly across the Gulf Coast States and GA. Broadly cyclonic flow still will prevail from the northern Rockies across the central/northern Plains and Great Lakes. Within that flow, a well-developed shortwave trough is evident in moisture- channel imagery from the Dakotas to northeastern CO, preceded closely by a smaller but convectively augmented perturbation over parts of IA, northwestern MO and eastern KS. As these features pivot through the broader cyclonic flow today, the leading perturbation's MCV should move across northern parts of IL/IN/OH and perhaps extreme southern Lower MI. The trailing, stronger trough should extend from central MN to central NE by 00Z, then cross the remainder of MN/NE and much of IA overnight with an at least intermittently closed 500-mb low. At the surface, the 11Z analysis showed a frontal-wave low over southwestern IA, with some possible augmentation from wake effects related to an area od precip/convection to the east and southeast. A wavy cold front, with several weak lows attached, was drawn from there across eastern/southern KS, the TX Panhandle, and north- central NM, preceded by outflow boundaries from northern OK across southern MO. By 00Z, the cold front should reach northwestern IL, central MO, southwestern OK, and central NM, with diffuse warm front over central parts of IL/IN/OH near or north of a convective boundary. By 12Z, the cold front should reach northwestern IN, southern IL, southern MO, southeastern OK, north-central/northwest TX, and southern NM. ...Southern Plains to lower Ohio Valley... Multiple rounds of convection are expected across this corridor today, contributing to the overall severe potential, without sharp demarcation between the three main regimes numbered below. The outlook has been expanded northeastward up the Ohio Valley in deference to an increased severe threat related both directly and indirectly to MCV-aided convection. 1. Ahead of the MCV and accompanying perturbation, a broad area of clouds and precip is apparent from central/northern MO across southern/central IL and extending into southern IN. The southern rim of this precip area contains scattered, initially non-severe thunderstorms, utilizing a broad warm-advection/moisture-transport plume with parcels isentropically lifted to an LFC. All this activity will continue to shift eastward through the remainder of the morning, helping to reinforce the ambient baroclinic zone across the area, which in turn should help to focus later/afternoon development. Meanwhile, some of the morning activity may encounter a diurnally destabilizing boundary layer with weakening MLCINH, more purely surface-based effective-inflow parcels, and rich boundary- layer moisture. The associated outflow/differential-heating boundary may shift somewhat northward today over southern/central parts of IL/IN before the leading perturbation passes, and also, can act to back low-level flow and enlarge hodographs, in a moisture- rich, low-LCL environment. As such, some supercell/tornado potential has become evident, with damaging gusts and isolated large hail also possible. 2. Closely following that regime, and perhaps blending with the western part of it, a round of widely scattered to scattered thunderstorms is expected along/ahead of the front from central/ southern MO to the lower Ohio Valley this afternoon into evening, as large-scale ascent from the stronger/trailing shortwave trough overspreads a still very moist air mass. Strong insolation and surface dewpoints in the low/mid 70s F will offset modest mid/upper- level lapse rates to yield MLCAPE in the 1500-2500 J/kg range south of the front and outflow boundary. While warm-sector surface flow will be weak, and more veered than on the boundary, sufficient deep/speed shear still should be present for a blend of multicells and at least transient supercells, with some clustering/bowing of convection possible as well. Damaging to severe gusts will be the main threats with this activity, though a tornado and isolated large hail may occur. 3. Vertical shear generally will weaken with westward extent near and ahead of the front, but substantially hotter surface conditions will contribute to very steep boundary-layer lapse rates and "inverted-v" thermodynamic profiles in the subcloud layer. A plume of 2000-2500 J/kg MLCAPE is expected over northern OK, decreasing southwestward across northwest TX into drier and still more deeply well-mixed conditions. As such, severe downdrafts and isolated large hail will be possible, with greatest potential concentration of the gust threat in the OK to southeast KS corridor. Activity forming in this regime also may persist and move/merge into the MO environment from late afternoon into evening. ...Upper Mississippi Valley region... Scattered thunderstorms are expected to develop as early as midday, and continue through the afternoon, east through southeast of the developing mid/upper low and primary vorticity maximum. Some of this convection will become supercells, capable of large hail and damaging gusts, with clustering or line segments also possible. The most favorable low-level parameter space for that convection to become severe still appears to be across southern MN, northern IA and western WI, where residual moisture north of the optimal warm sector still will support surface dewpoints in the mid 60s F, amid pockets of favorable diurnal heating and low-level warm advection behind the morning cloud/precip plume. Large-scale ascent will occur in relation to midlevel DCVA preceding the trough aloft, and the left-exit region of a cyclonically curved, 250-300-mb speed max. Though low-level flow should be modest, favorable deep shear (effective-shear magnitudes in the 45-55-kt range) will support organized convection for several hours. Overall, this activity should diminish through the evening as nocturnal cooling and expansive outflow air collectively stabilize the boundary layer. ..Edwards/Kerr.. 07/04/2024 Read more

000
ABPZ20 KNHC 041144
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Thu Jul 4 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Offshore of Southwestern Mexico (EP91):
An area of low pressure located a couple of hundred miles offshore
of the southwestern coast of Mexico continues to produce a small
area of showers and thunderstorms. Although this activity has become
better organized since yesterday, it remains unclear whether the
system possesses a well-defined center. Environmental conditions
could still support the formation of a short-lived tropical
depression later today or tonight while the system moves
northwestward offshore of the southwestern coast of Mexico. By
Friday, the system is forecast to move over cooler waters and
further development is not expected.
* Formation chance through 48 hours...medium....60 percent.
* Formation chance through 7 days...medium...60 percent.

$$
Forecaster Reinhart

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Thu Jul 04 2024 Valid 071200Z - 121200Z ...DISCUSSION... ...D4/Sunday... The upper-level trough will dig slightly farther south into Oklahoma before lifting northeastward on Monday. For portions of the central/southern Plains, both the ECMWF and GFS suggest that convection will develop along the intersection of the cold and warm front within a weak surface low. Similar to Saturday, moisture will not be overly rich, but northward moisture return will be in progress. Convection is forecast to grow upscale into an MCS and move southward into the greater buoyancy. With differences in the position and intensity of the surface low, as well as possible impacts from convection on Saturday, predictability remains too low for the introduction of 15% total severe probabilities. TC Beryl continues to move towards the Yucatan Peninsula and is expected to reach the Mexican coast south of Brownsville, TX on Sunday per latest NHC forecasts. Some tornado risk is possible for parts of South Texas, but magnitude and spatial extent of this risk will depend on how much the TC restrengthens after interacting with the Peninsula and where the system will actually track late this weekend into early next week. ...D5/Monday and beyond... The upper-level trough will slowly make progress into the Midwest and eventually into the Ohio Valley and Northeast. While some severe risk is possible ahead of this trough, questions regarding destabilization and general lack of robust surface features during the upcoming week keep confidence too low for highlights at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Thu Jul 04 2024 Valid 071200Z - 121200Z ...DISCUSSION... ...D4/Sunday... The upper-level trough will dig slightly farther south into Oklahoma before lifting northeastward on Monday. For portions of the central/southern Plains, both the ECMWF and GFS suggest that convection will develop along the intersection of the cold and warm front within a weak surface low. Similar to Saturday, moisture will not be overly rich, but northward moisture return will be in progress. Convection is forecast to grow upscale into an MCS and move southward into the greater buoyancy. With differences in the position and intensity of the surface low, as well as possible impacts from convection on Saturday, predictability remains too low for the introduction of 15% total severe probabilities. TC Beryl continues to move towards the Yucatan Peninsula and is expected to reach the Mexican coast south of Brownsville, TX on Sunday per latest NHC forecasts. Some tornado risk is possible for parts of South Texas, but magnitude and spatial extent of this risk will depend on how much the TC restrengthens after interacting with the Peninsula and where the system will actually track late this weekend into early next week. ...D5/Monday and beyond... The upper-level trough will slowly make progress into the Midwest and eventually into the Ohio Valley and Northeast. While some severe risk is possible ahead of this trough, questions regarding destabilization and general lack of robust surface features during the upcoming week keep confidence too low for highlights at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Thu Jul 04 2024 Valid 071200Z - 121200Z ...DISCUSSION... ...D4/Sunday... The upper-level trough will dig slightly farther south into Oklahoma before lifting northeastward on Monday. For portions of the central/southern Plains, both the ECMWF and GFS suggest that convection will develop along the intersection of the cold and warm front within a weak surface low. Similar to Saturday, moisture will not be overly rich, but northward moisture return will be in progress. Convection is forecast to grow upscale into an MCS and move southward into the greater buoyancy. With differences in the position and intensity of the surface low, as well as possible impacts from convection on Saturday, predictability remains too low for the introduction of 15% total severe probabilities. TC Beryl continues to move towards the Yucatan Peninsula and is expected to reach the Mexican coast south of Brownsville, TX on Sunday per latest NHC forecasts. Some tornado risk is possible for parts of South Texas, but magnitude and spatial extent of this risk will depend on how much the TC restrengthens after interacting with the Peninsula and where the system will actually track late this weekend into early next week. ...D5/Monday and beyond... The upper-level trough will slowly make progress into the Midwest and eventually into the Ohio Valley and Northeast. While some severe risk is possible ahead of this trough, questions regarding destabilization and general lack of robust surface features during the upcoming week keep confidence too low for highlights at this time. Read more