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MD 1721 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF WESTERN/CENTRAL NE
Mesoscale Discussion 1721 NWS Storm Prediction Center Norman OK 0856 AM CDT Tue Aug 13 2019 Areas affected...Portions of western/central NE Concerning...Severe potential...Watch unlikely Valid 131356Z - 131530Z Probability of Watch Issuance...20 percent SUMMARY...An isolated large hail risk may continue this morning with ongoing thunderstorms. Watch issuance is unlikely in the short term. DISCUSSION...A pair of elevated supercells has evolved this morning in southern Cherry County NE within a warm air advection regime maximized around 700 mb. Short-term guidance, including the latest run of the RAP, suggests that 25-35 kt of southwesterly flow centered around 700 mb may persist through the rest of the morning. These winds, along with 35-40 kt of effective bulk shear, could maintain storm intensities as they develop southeastward along an instability gradient present across western/central NE. Isolated large hail will remain the primary threat for the next couple of hours given a stable near-surface layer noted on the 12Z sounding from LBF. Regardless, this hail threat will likely remain too isolated to justify watch issuance in the short term (through the rest of the morning). But, the severe threat will likely increase later today across parts of southern/western NE as the atmosphere destabilizes and surface-based storms develop. ..Gleason/Grams.. 08/13/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...CYS... LAT...LON 42580301 42870292 42910242 42280099 41710028 41140025 40740043 40740117 41310187 41990253 42580301 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 AM CDT Tue Aug 13 2019 Valid 131300Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS VA...AND THIS AFTERNOON/EVENING ACROSS THE CENTRAL HIGH PLAINS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EXTENDING WESTWARD FROM THE MID-ATLANTIC ACROSS TN... ...SUMMARY... Scattered severe thunderstorms with damaging winds are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms with very large hail and damaging winds should also develop across the central High Plains. ...Synopsis... The primary larger-scale features today are northern stream troughs moving east-southeastward over Quebec and ND/MN, though a separate/weaker belt of westerlies is located farther south from the central Plains across the OH Valley to the Mid-Atlantic. Within this southern flow belt, diffuse MCVs are progressing east-southeastward over MO/IL and OH/WV, with ongoing convection in multiple clusters through this corridor. The stronger storms along the lower OH River are producing a cold pool and will likely persist until at least late morning, with the southward extent of the outflow likely demarcating the zone of afternoon redevelopment of storms this afternoon across TN. A few damaging gusts will be the main threats with multicell clusters/line segments in an environment of rich low-level moisture and moderate buoyancy along the southern edge of the 25-35 kt midlevel flow. The ongoing convection from southern OH to WV has shown signs of weakening slowly this morning. Still, residual clouds and some rain will slow surface heating from roughly 15-19z across central/northern VA, with the more probable zone of stronger destabilization along the southern fringe of the morning clouds/rain in the vicinity of southern VA. Upstream VWPs reveal 40 kt midlevel flow as low as 4 km above ground level over southern OH/eastern KY/WV, and this somewhat stronger flow will translate over VA this afternoon with the remnant MCV. Will maintain the 30% wind/Enhanced risk area in this update, though the influence of clouds on destabilization through early afternoon will likely modulate additional storm development this afternoon, and potentially reduce the severe threat. ...Central High Plains this afternoon through early tonight... A low-level upslope flow regime will establish today across eastern CO, prior to a weak reinforcing frontal surge overnight. South of an ongoing band of elevated storms driven by midlevel warm advection/frontogenesis, the low levels will warm and MLCAPE is expected to increase to 2000-3000 J/kg by mid-late afternoon. Deep-layer vertical shear will be favorable for supercells from northeast CO/northwest KS northward. Surface-based storm development is expected 21-00z across northeast CO along a surface trough on the northeast edge of the steeper low-level lapse rates and deeper mixing. The initial storms will likely be discrete supercells capable of producing isolated very large hail and perhaps a tornado or two. Convection may grow into a larger cluster this evening and propagate southward into a weak nocturnal low-level jet across far eastern CO/western KS, with a continuing threat for damaging winds into early tonight. ...Upper MS Valley area this afternoon... A midlevel shortwave trough over eastern ND this morning will move southeastward over MN/western WI by this evening. Ascent preceding the midlevel trough will coincide with daytime heating and low-level convergence along a weak northwest-southeast oriented front, which will support thunderstorm development this afternoon. Boundary-layer dewpoints in the 60s and afternoon surface temperatures approaching 80 F will drive MLCAPE of 1000-1500 J/kg, in an environment with effective bulk shear near 40 kt. The net result will be the potential for a few organized/supercell storms capable of producing isolated damaging winds/large hail. An isolated tornado may also occur with storms moving southeastward along the boundary, where low-level shear and vertical vorticity will be larger. ..Thompson/Kerr.. 08/13/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 AM CDT Tue Aug 13 2019 Valid 131300Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS VA...AND THIS AFTERNOON/EVENING ACROSS THE CENTRAL HIGH PLAINS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EXTENDING WESTWARD FROM THE MID-ATLANTIC ACROSS TN... ...SUMMARY... Scattered severe thunderstorms with damaging winds are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms with very large hail and damaging winds should also develop across the central High Plains. ...Synopsis... The primary larger-scale features today are northern stream troughs moving east-southeastward over Quebec and ND/MN, though a separate/weaker belt of westerlies is located farther south from the central Plains across the OH Valley to the Mid-Atlantic. Within this southern flow belt, diffuse MCVs are progressing east-southeastward over MO/IL and OH/WV, with ongoing convection in multiple clusters through this corridor. The stronger storms along the lower OH River are producing a cold pool and will likely persist until at least late morning, with the southward extent of the outflow likely demarcating the zone of afternoon redevelopment of storms this afternoon across TN. A few damaging gusts will be the main threats with multicell clusters/line segments in an environment of rich low-level moisture and moderate buoyancy along the southern edge of the 25-35 kt midlevel flow. The ongoing convection from southern OH to WV has shown signs of weakening slowly this morning. Still, residual clouds and some rain will slow surface heating from roughly 15-19z across central/northern VA, with the more probable zone of stronger destabilization along the southern fringe of the morning clouds/rain in the vicinity of southern VA. Upstream VWPs reveal 40 kt midlevel flow as low as 4 km above ground level over southern OH/eastern KY/WV, and this somewhat stronger flow will translate over VA this afternoon with the remnant MCV. Will maintain the 30% wind/Enhanced risk area in this update, though the influence of clouds on destabilization through early afternoon will likely modulate additional storm development this afternoon, and potentially reduce the severe threat. ...Central High Plains this afternoon through early tonight... A low-level upslope flow regime will establish today across eastern CO, prior to a weak reinforcing frontal surge overnight. South of an ongoing band of elevated storms driven by midlevel warm advection/frontogenesis, the low levels will warm and MLCAPE is expected to increase to 2000-3000 J/kg by mid-late afternoon. Deep-layer vertical shear will be favorable for supercells from northeast CO/northwest KS northward. Surface-based storm development is expected 21-00z across northeast CO along a surface trough on the northeast edge of the steeper low-level lapse rates and deeper mixing. The initial storms will likely be discrete supercells capable of producing isolated very large hail and perhaps a tornado or two. Convection may grow into a larger cluster this evening and propagate southward into a weak nocturnal low-level jet across far eastern CO/western KS, with a continuing threat for damaging winds into early tonight. ...Upper MS Valley area this afternoon... A midlevel shortwave trough over eastern ND this morning will move southeastward over MN/western WI by this evening. Ascent preceding the midlevel trough will coincide with daytime heating and low-level convergence along a weak northwest-southeast oriented front, which will support thunderstorm development this afternoon. Boundary-layer dewpoints in the 60s and afternoon surface temperatures approaching 80 F will drive MLCAPE of 1000-1500 J/kg, in an environment with effective bulk shear near 40 kt. The net result will be the potential for a few organized/supercell storms capable of producing isolated damaging winds/large hail. An isolated tornado may also occur with storms moving southeastward along the boundary, where low-level shear and vertical vorticity will be larger. ..Thompson/Kerr.. 08/13/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 AM CDT Tue Aug 13 2019 Valid 131300Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS VA...AND THIS AFTERNOON/EVENING ACROSS THE CENTRAL HIGH PLAINS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EXTENDING WESTWARD FROM THE MID-ATLANTIC ACROSS TN... ...SUMMARY... Scattered severe thunderstorms with damaging winds are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms with very large hail and damaging winds should also develop across the central High Plains. ...Synopsis... The primary larger-scale features today are northern stream troughs moving east-southeastward over Quebec and ND/MN, though a separate/weaker belt of westerlies is located farther south from the central Plains across the OH Valley to the Mid-Atlantic. Within this southern flow belt, diffuse MCVs are progressing east-southeastward over MO/IL and OH/WV, with ongoing convection in multiple clusters through this corridor. The stronger storms along the lower OH River are producing a cold pool and will likely persist until at least late morning, with the southward extent of the outflow likely demarcating the zone of afternoon redevelopment of storms this afternoon across TN. A few damaging gusts will be the main threats with multicell clusters/line segments in an environment of rich low-level moisture and moderate buoyancy along the southern edge of the 25-35 kt midlevel flow. The ongoing convection from southern OH to WV has shown signs of weakening slowly this morning. Still, residual clouds and some rain will slow surface heating from roughly 15-19z across central/northern VA, with the more probable zone of stronger destabilization along the southern fringe of the morning clouds/rain in the vicinity of southern VA. Upstream VWPs reveal 40 kt midlevel flow as low as 4 km above ground level over southern OH/eastern KY/WV, and this somewhat stronger flow will translate over VA this afternoon with the remnant MCV. Will maintain the 30% wind/Enhanced risk area in this update, though the influence of clouds on destabilization through early afternoon will likely modulate additional storm development this afternoon, and potentially reduce the severe threat. ...Central High Plains this afternoon through early tonight... A low-level upslope flow regime will establish today across eastern CO, prior to a weak reinforcing frontal surge overnight. South of an ongoing band of elevated storms driven by midlevel warm advection/frontogenesis, the low levels will warm and MLCAPE is expected to increase to 2000-3000 J/kg by mid-late afternoon. Deep-layer vertical shear will be favorable for supercells from northeast CO/northwest KS northward. Surface-based storm development is expected 21-00z across northeast CO along a surface trough on the northeast edge of the steeper low-level lapse rates and deeper mixing. The initial storms will likely be discrete supercells capable of producing isolated very large hail and perhaps a tornado or two. Convection may grow into a larger cluster this evening and propagate southward into a weak nocturnal low-level jet across far eastern CO/western KS, with a continuing threat for damaging winds into early tonight. ...Upper MS Valley area this afternoon... A midlevel shortwave trough over eastern ND this morning will move southeastward over MN/western WI by this evening. Ascent preceding the midlevel trough will coincide with daytime heating and low-level convergence along a weak northwest-southeast oriented front, which will support thunderstorm development this afternoon. Boundary-layer dewpoints in the 60s and afternoon surface temperatures approaching 80 F will drive MLCAPE of 1000-1500 J/kg, in an environment with effective bulk shear near 40 kt. The net result will be the potential for a few organized/supercell storms capable of producing isolated damaging winds/large hail. An isolated tornado may also occur with storms moving southeastward along the boundary, where low-level shear and vertical vorticity will be larger. ..Thompson/Kerr.. 08/13/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 AM CDT Tue Aug 13 2019 Valid 131300Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS VA...AND THIS AFTERNOON/EVENING ACROSS THE CENTRAL HIGH PLAINS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EXTENDING WESTWARD FROM THE MID-ATLANTIC ACROSS TN... ...SUMMARY... Scattered severe thunderstorms with damaging winds are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms with very large hail and damaging winds should also develop across the central High Plains. ...Synopsis... The primary larger-scale features today are northern stream troughs moving east-southeastward over Quebec and ND/MN, though a separate/weaker belt of westerlies is located farther south from the central Plains across the OH Valley to the Mid-Atlantic. Within this southern flow belt, diffuse MCVs are progressing east-southeastward over MO/IL and OH/WV, with ongoing convection in multiple clusters through this corridor. The stronger storms along the lower OH River are producing a cold pool and will likely persist until at least late morning, with the southward extent of the outflow likely demarcating the zone of afternoon redevelopment of storms this afternoon across TN. A few damaging gusts will be the main threats with multicell clusters/line segments in an environment of rich low-level moisture and moderate buoyancy along the southern edge of the 25-35 kt midlevel flow. The ongoing convection from southern OH to WV has shown signs of weakening slowly this morning. Still, residual clouds and some rain will slow surface heating from roughly 15-19z across central/northern VA, with the more probable zone of stronger destabilization along the southern fringe of the morning clouds/rain in the vicinity of southern VA. Upstream VWPs reveal 40 kt midlevel flow as low as 4 km above ground level over southern OH/eastern KY/WV, and this somewhat stronger flow will translate over VA this afternoon with the remnant MCV. Will maintain the 30% wind/Enhanced risk area in this update, though the influence of clouds on destabilization through early afternoon will likely modulate additional storm development this afternoon, and potentially reduce the severe threat. ...Central High Plains this afternoon through early tonight... A low-level upslope flow regime will establish today across eastern CO, prior to a weak reinforcing frontal surge overnight. South of an ongoing band of elevated storms driven by midlevel warm advection/frontogenesis, the low levels will warm and MLCAPE is expected to increase to 2000-3000 J/kg by mid-late afternoon. Deep-layer vertical shear will be favorable for supercells from northeast CO/northwest KS northward. Surface-based storm development is expected 21-00z across northeast CO along a surface trough on the northeast edge of the steeper low-level lapse rates and deeper mixing. The initial storms will likely be discrete supercells capable of producing isolated very large hail and perhaps a tornado or two. Convection may grow into a larger cluster this evening and propagate southward into a weak nocturnal low-level jet across far eastern CO/western KS, with a continuing threat for damaging winds into early tonight. ...Upper MS Valley area this afternoon... A midlevel shortwave trough over eastern ND this morning will move southeastward over MN/western WI by this evening. Ascent preceding the midlevel trough will coincide with daytime heating and low-level convergence along a weak northwest-southeast oriented front, which will support thunderstorm development this afternoon. Boundary-layer dewpoints in the 60s and afternoon surface temperatures approaching 80 F will drive MLCAPE of 1000-1500 J/kg, in an environment with effective bulk shear near 40 kt. The net result will be the potential for a few organized/supercell storms capable of producing isolated damaging winds/large hail. An isolated tornado may also occur with storms moving southeastward along the boundary, where low-level shear and vertical vorticity will be larger. ..Thompson/Kerr.. 08/13/2019 Read more

000
ABPZ20 KNHC 131141
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Tue Aug 13 2019

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

The National Hurricane Center is issuing advisories on recently
downgraded Tropical Depression Henriette, located a few hundred
miles west-southwest of the southern tip of the Baja California
peninsula.

Disorganized showers and thunderstorms located about 1100 miles
southwest of the southern tip of the Baja California peninsula are
associated with an elongated trough of low pressure. Environmental
conditions are forecast to be conducive for gradual development
during the next few days, and a tropical depression is likely to
form later this week while the system moves west-northwestward at
10 to 15 mph.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...high...70 percent.

A broad area of low pressure is forecast to form south or
southeast of the southeastern coast of Mexico late this week.
Environmental conditions are expected to be conducive for gradual
development of the system over the weekend.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

$$
Forecaster Pasch

5-Day Uncertainty Track last updated Tue, 13 Aug 2019 08:33:37 GMT


Wind Speed Probabilities last updated Tue, 13 Aug 2019 15:24:25 GMT

...HENRIETTE WEAKENING QUICKLY... ...EXPECTED TO BECOME A REMNANT LOW LATER TODAY... As of 2:00 AM PDT Tue Aug 13 the center of Henriette was located near 21.1, -115.2 with movement WNW at 13 mph. The minimum central pressure was 1008 mb with maximum sustained winds of about 30 mph.

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0245 AM CDT Tue Aug 13 2019 Valid 161200Z - 211200Z ...DISCUSSION... An area of moderate westerlies aloft will remain over the northern CONUS on Fri/D4 and Sat/D5, but will lift north into Canada during the Sun/D6-Sat/D7 period. During that time, an upper ridge will build over the West with the high centered over AZ. On Fri/D4, the GFS indicates a low-amplitude shortwave trough moving from WY across SD, NE, and into IA, with an associated cold front, but the ECMWF is less amplified with this feature. In addition, there are major discrepancies with latitudinal placement of the larger instability (KS vs NE). As such, predictability is too low for Friday, though severe weather is possible (mainly wind gusts) in this general region. For the period from Sat/D5 into Sun/D6, ample moisture and instability will remain from the central Plains into the mid and upper MS Valley as a larger trough amplification occurs over south-central Canada, extending south into the northern Plains. Aside from timing issues amongst the various models with this trough, daily cycles of thunderstorms further decrease predictability regarding the best threat corridors. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0245 AM CDT Tue Aug 13 2019 Valid 161200Z - 211200Z ...DISCUSSION... An area of moderate westerlies aloft will remain over the northern CONUS on Fri/D4 and Sat/D5, but will lift north into Canada during the Sun/D6-Sat/D7 period. During that time, an upper ridge will build over the West with the high centered over AZ. On Fri/D4, the GFS indicates a low-amplitude shortwave trough moving from WY across SD, NE, and into IA, with an associated cold front, but the ECMWF is less amplified with this feature. In addition, there are major discrepancies with latitudinal placement of the larger instability (KS vs NE). As such, predictability is too low for Friday, though severe weather is possible (mainly wind gusts) in this general region. For the period from Sat/D5 into Sun/D6, ample moisture and instability will remain from the central Plains into the mid and upper MS Valley as a larger trough amplification occurs over south-central Canada, extending south into the northern Plains. Aside from timing issues amongst the various models with this trough, daily cycles of thunderstorms further decrease predictability regarding the best threat corridors. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0245 AM CDT Tue Aug 13 2019 Valid 161200Z - 211200Z ...DISCUSSION... An area of moderate westerlies aloft will remain over the northern CONUS on Fri/D4 and Sat/D5, but will lift north into Canada during the Sun/D6-Sat/D7 period. During that time, an upper ridge will build over the West with the high centered over AZ. On Fri/D4, the GFS indicates a low-amplitude shortwave trough moving from WY across SD, NE, and into IA, with an associated cold front, but the ECMWF is less amplified with this feature. In addition, there are major discrepancies with latitudinal placement of the larger instability (KS vs NE). As such, predictability is too low for Friday, though severe weather is possible (mainly wind gusts) in this general region. For the period from Sat/D5 into Sun/D6, ample moisture and instability will remain from the central Plains into the mid and upper MS Valley as a larger trough amplification occurs over south-central Canada, extending south into the northern Plains. Aside from timing issues amongst the various models with this trough, daily cycles of thunderstorms further decrease predictability regarding the best threat corridors. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Tue Aug 13 2019 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE CENTRAL PLAINS... ...SUMMARY... A few severe storms are possible across much of the central Plains on Thursday. ...Synopsis and Discussion... A belt of 30-40 kt midlevel winds, increasing to 50-60 kt in the upper levels, will stretch from the northern Rockies across the central Plains and into the mid MS Valley on Thursday with various embedded disturbances within the flow. In general, a trough of low pressure is forecast to develop over the central and southern High Plains, with mid to upper 60s F dewpoints to about I-70 in KS. Given relatively cool temperatures aloft, this will result in areas of strong instability over parts of the central Plains. Complicating the forecast will be the possibility of early storms moving across parts of NE and KS, likely situated on the nose of a 20-30 kt low-level jet. Some of these storms may produce locally severe wind gusts. Later in the day, the air mass south and west of any outflow boundaries may serve as a focus for new development, again with an MCS possible with damaging wind potential. At this time, predictability is too low to place a Slight Risk. Farther north, storms are expected to develop by late morning or midday over SD in association with a low-amplitude wave moving out of MT. Here, cold temperatures aloft and long hodographs will favor both hail and wind as storms form along a weak cold front. Finally, isolated storms capable of hail are possible along the Front Range during the peak heating hours, with cold profiles aloft beneath ample westerlies. Parts of the area will likely be upgraded to a Slight Risk in later outlooks when predictability increases. ..Jewell.. 08/13/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Tue Aug 13 2019 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE CENTRAL PLAINS... ...SUMMARY... A few severe storms are possible across much of the central Plains on Thursday. ...Synopsis and Discussion... A belt of 30-40 kt midlevel winds, increasing to 50-60 kt in the upper levels, will stretch from the northern Rockies across the central Plains and into the mid MS Valley on Thursday with various embedded disturbances within the flow. In general, a trough of low pressure is forecast to develop over the central and southern High Plains, with mid to upper 60s F dewpoints to about I-70 in KS. Given relatively cool temperatures aloft, this will result in areas of strong instability over parts of the central Plains. Complicating the forecast will be the possibility of early storms moving across parts of NE and KS, likely situated on the nose of a 20-30 kt low-level jet. Some of these storms may produce locally severe wind gusts. Later in the day, the air mass south and west of any outflow boundaries may serve as a focus for new development, again with an MCS possible with damaging wind potential. At this time, predictability is too low to place a Slight Risk. Farther north, storms are expected to develop by late morning or midday over SD in association with a low-amplitude wave moving out of MT. Here, cold temperatures aloft and long hodographs will favor both hail and wind as storms form along a weak cold front. Finally, isolated storms capable of hail are possible along the Front Range during the peak heating hours, with cold profiles aloft beneath ample westerlies. Parts of the area will likely be upgraded to a Slight Risk in later outlooks when predictability increases. ..Jewell.. 08/13/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Tue Aug 13 2019 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE CENTRAL PLAINS... ...SUMMARY... A few severe storms are possible across much of the central Plains on Thursday. ...Synopsis and Discussion... A belt of 30-40 kt midlevel winds, increasing to 50-60 kt in the upper levels, will stretch from the northern Rockies across the central Plains and into the mid MS Valley on Thursday with various embedded disturbances within the flow. In general, a trough of low pressure is forecast to develop over the central and southern High Plains, with mid to upper 60s F dewpoints to about I-70 in KS. Given relatively cool temperatures aloft, this will result in areas of strong instability over parts of the central Plains. Complicating the forecast will be the possibility of early storms moving across parts of NE and KS, likely situated on the nose of a 20-30 kt low-level jet. Some of these storms may produce locally severe wind gusts. Later in the day, the air mass south and west of any outflow boundaries may serve as a focus for new development, again with an MCS possible with damaging wind potential. At this time, predictability is too low to place a Slight Risk. Farther north, storms are expected to develop by late morning or midday over SD in association with a low-amplitude wave moving out of MT. Here, cold temperatures aloft and long hodographs will favor both hail and wind as storms form along a weak cold front. Finally, isolated storms capable of hail are possible along the Front Range during the peak heating hours, with cold profiles aloft beneath ample westerlies. Parts of the area will likely be upgraded to a Slight Risk in later outlooks when predictability increases. ..Jewell.. 08/13/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Tue Aug 13 2019 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE CENTRAL PLAINS... ...SUMMARY... A few severe storms are possible across much of the central Plains on Thursday. ...Synopsis and Discussion... A belt of 30-40 kt midlevel winds, increasing to 50-60 kt in the upper levels, will stretch from the northern Rockies across the central Plains and into the mid MS Valley on Thursday with various embedded disturbances within the flow. In general, a trough of low pressure is forecast to develop over the central and southern High Plains, with mid to upper 60s F dewpoints to about I-70 in KS. Given relatively cool temperatures aloft, this will result in areas of strong instability over parts of the central Plains. Complicating the forecast will be the possibility of early storms moving across parts of NE and KS, likely situated on the nose of a 20-30 kt low-level jet. Some of these storms may produce locally severe wind gusts. Later in the day, the air mass south and west of any outflow boundaries may serve as a focus for new development, again with an MCS possible with damaging wind potential. At this time, predictability is too low to place a Slight Risk. Farther north, storms are expected to develop by late morning or midday over SD in association with a low-amplitude wave moving out of MT. Here, cold temperatures aloft and long hodographs will favor both hail and wind as storms form along a weak cold front. Finally, isolated storms capable of hail are possible along the Front Range during the peak heating hours, with cold profiles aloft beneath ample westerlies. Parts of the area will likely be upgraded to a Slight Risk in later outlooks when predictability increases. ..Jewell.. 08/13/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN COLORADO INTO WESTERN NEBRASKA AND KANSAS... ...SUMMARY... Scattered strong to severe storms with damaging hail and wind will be possible over the central High Plains Wednesday afternoon and evening, with isolated severe wind gusts from parts of the Gulf Coast to the eastern Carolinas. ...Synopsis... Northwest flow aloft will stretch from the Pacific Northwest across the northern Rockies and into the central Plains with a low-amplitude shortwave trough entering the northern High Plains late in the day. To the east, another wave will move across northern New England, with relatively cool temperatures aloft remaining over the OH Valley beneath westerly flow. At the surface, relatively dry air will exist from the northern Plains eastward across the Great Lakes and into New England, while a weak surface trough extends from the Mid Atlantic across the northern Gulf Coast and into central TX. Seasonally moist conditions will exist along the southern boundary supporting scattered afternoon storms. To the west, a lee trough will develop over the central High Plains where southeasterly surface winds will maintain moist and unstable conditions beneath moderate northwest winds aloft, favoring severe storms. ...Central High Plains... Southeast surface winds will maintain mid 50s to near 60 F dewpoints to the Front Range as strong heating reduces capping, possibly in the wake of storms the previous night. Storms are expected to initiate around 21Z from eastern WY across the Black Hills, and southward into northeast CO. Relatively long hodographs will favor splitting cells capable of large hail. An MCS is possible by evening into western NE or northwest KS as the low-level jet increases to 30 kt out of the south. A brief tornado cannot be ruled out with any right-moving supercells. ...Gulf Coast States to the Carolinas... Strong heating of a moist air mass will lead to strong instability by afternoon, with MUCAPE in excess of 3000 J/kg from the Sabine River to the eastern Carolinas. Convergence near the boundary will provide a focus for storms, with very weak winds aloft favoring pulse severe capable of localized damaging winds, perhaps with small hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 08/13/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN COLORADO INTO WESTERN NEBRASKA AND KANSAS... ...SUMMARY... Scattered strong to severe storms with damaging hail and wind will be possible over the central High Plains Wednesday afternoon and evening, with isolated severe wind gusts from parts of the Gulf Coast to the eastern Carolinas. ...Synopsis... Northwest flow aloft will stretch from the Pacific Northwest across the northern Rockies and into the central Plains with a low-amplitude shortwave trough entering the northern High Plains late in the day. To the east, another wave will move across northern New England, with relatively cool temperatures aloft remaining over the OH Valley beneath westerly flow. At the surface, relatively dry air will exist from the northern Plains eastward across the Great Lakes and into New England, while a weak surface trough extends from the Mid Atlantic across the northern Gulf Coast and into central TX. Seasonally moist conditions will exist along the southern boundary supporting scattered afternoon storms. To the west, a lee trough will develop over the central High Plains where southeasterly surface winds will maintain moist and unstable conditions beneath moderate northwest winds aloft, favoring severe storms. ...Central High Plains... Southeast surface winds will maintain mid 50s to near 60 F dewpoints to the Front Range as strong heating reduces capping, possibly in the wake of storms the previous night. Storms are expected to initiate around 21Z from eastern WY across the Black Hills, and southward into northeast CO. Relatively long hodographs will favor splitting cells capable of large hail. An MCS is possible by evening into western NE or northwest KS as the low-level jet increases to 30 kt out of the south. A brief tornado cannot be ruled out with any right-moving supercells. ...Gulf Coast States to the Carolinas... Strong heating of a moist air mass will lead to strong instability by afternoon, with MUCAPE in excess of 3000 J/kg from the Sabine River to the eastern Carolinas. Convergence near the boundary will provide a focus for storms, with very weak winds aloft favoring pulse severe capable of localized damaging winds, perhaps with small hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 08/13/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN COLORADO INTO WESTERN NEBRASKA AND KANSAS... ...SUMMARY... Scattered strong to severe storms with damaging hail and wind will be possible over the central High Plains Wednesday afternoon and evening, with isolated severe wind gusts from parts of the Gulf Coast to the eastern Carolinas. ...Synopsis... Northwest flow aloft will stretch from the Pacific Northwest across the northern Rockies and into the central Plains with a low-amplitude shortwave trough entering the northern High Plains late in the day. To the east, another wave will move across northern New England, with relatively cool temperatures aloft remaining over the OH Valley beneath westerly flow. At the surface, relatively dry air will exist from the northern Plains eastward across the Great Lakes and into New England, while a weak surface trough extends from the Mid Atlantic across the northern Gulf Coast and into central TX. Seasonally moist conditions will exist along the southern boundary supporting scattered afternoon storms. To the west, a lee trough will develop over the central High Plains where southeasterly surface winds will maintain moist and unstable conditions beneath moderate northwest winds aloft, favoring severe storms. ...Central High Plains... Southeast surface winds will maintain mid 50s to near 60 F dewpoints to the Front Range as strong heating reduces capping, possibly in the wake of storms the previous night. Storms are expected to initiate around 21Z from eastern WY across the Black Hills, and southward into northeast CO. Relatively long hodographs will favor splitting cells capable of large hail. An MCS is possible by evening into western NE or northwest KS as the low-level jet increases to 30 kt out of the south. A brief tornado cannot be ruled out with any right-moving supercells. ...Gulf Coast States to the Carolinas... Strong heating of a moist air mass will lead to strong instability by afternoon, with MUCAPE in excess of 3000 J/kg from the Sabine River to the eastern Carolinas. Convergence near the boundary will provide a focus for storms, with very weak winds aloft favoring pulse severe capable of localized damaging winds, perhaps with small hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 08/13/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 13 2019 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN COLORADO INTO WESTERN NEBRASKA AND KANSAS... ...SUMMARY... Scattered strong to severe storms with damaging hail and wind will be possible over the central High Plains Wednesday afternoon and evening, with isolated severe wind gusts from parts of the Gulf Coast to the eastern Carolinas. ...Synopsis... Northwest flow aloft will stretch from the Pacific Northwest across the northern Rockies and into the central Plains with a low-amplitude shortwave trough entering the northern High Plains late in the day. To the east, another wave will move across northern New England, with relatively cool temperatures aloft remaining over the OH Valley beneath westerly flow. At the surface, relatively dry air will exist from the northern Plains eastward across the Great Lakes and into New England, while a weak surface trough extends from the Mid Atlantic across the northern Gulf Coast and into central TX. Seasonally moist conditions will exist along the southern boundary supporting scattered afternoon storms. To the west, a lee trough will develop over the central High Plains where southeasterly surface winds will maintain moist and unstable conditions beneath moderate northwest winds aloft, favoring severe storms. ...Central High Plains... Southeast surface winds will maintain mid 50s to near 60 F dewpoints to the Front Range as strong heating reduces capping, possibly in the wake of storms the previous night. Storms are expected to initiate around 21Z from eastern WY across the Black Hills, and southward into northeast CO. Relatively long hodographs will favor splitting cells capable of large hail. An MCS is possible by evening into western NE or northwest KS as the low-level jet increases to 30 kt out of the south. A brief tornado cannot be ruled out with any right-moving supercells. ...Gulf Coast States to the Carolinas... Strong heating of a moist air mass will lead to strong instability by afternoon, with MUCAPE in excess of 3000 J/kg from the Sabine River to the eastern Carolinas. Convergence near the boundary will provide a focus for storms, with very weak winds aloft favoring pulse severe capable of localized damaging winds, perhaps with small hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Jewell.. 08/13/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Tue Aug 13 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE TN VALLEY AND OVER THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms are expected across the southern Middle Atlantic into the Tennessee Valley. Severe thunderstorms should also develop across the central High Plains. ...Middle Atlantic/TN Valley... Early-morning water-vapor imagery depicts a mid-level vort max over central IL which appears to be partly responsible for organized deep convection over the lower OH Valley. This feature is forecast to progress east-southeast across the OH Valley and leading edge of affiliated MCS is expected to spread into WV shortly after sunrise. Considerable amount of clouds/precipitation should limit buoyancy across the central Appalachians while models favor stronger boundary-layer heating downstream across the Piedmont. For these reasons will lower severe probs across WV/western VA and orient ENH Risk east of the mountains where renewed thunderstorm development is expected by early afternoon. Damaging winds are the primary severe threat with scattered severe storms as they organize across the Piedmont. While initial convection may be cellular in nature, line segments capable of producing wind should mature across the southern Delmarva into southern VA. Scattered severe thunderstorms are also expected to develop along weak frontal zone as it sags southeast across KY/TN during the afternoon. This activity will evolve along southern fringe of modest northwesterly flow which should contribute to some organization. Strong storms may spread as far south as northern AL by late evening. ...Central High Plains... Weak mid-level height rises are forecast across the Great Basin Tuesday which should maintain modest 500mb flow across the central High Plains along the front side of southwestern U.S. anticyclone. While it's not evident that any meaningful disturbance will approach southern WY/NE, strong boundary-layer heating is forecast across eastern WY/CO. Forecast soundings suggest surface parcels will reach their convective temperatures by 20-21z. Early-evening CAMs aggressively develop convection across this region with supercell structures forecast early in the convective cycle. Local hail algorithm generates hail in excess of 2" and this seems reasonable given the steep lapse rates and seasonally high buoyancy. There is some concern that scattered supercells will merge into an MCS that should propagate southeast across western KS toward northwestern OK during the overnight hours. Wind threat should increase if an organized squall line emerges across this region. ...Upper MS Valley... Notable short-wave trough is beginning to dig southeast across the northern Plains. Large-scale forcing ahead of this feature is forecast to spread across southeast MN/western WI by early afternoon. In response to the short wave, weak surface low will develop over southeast MN which should enhance low-level convergence for isolated thunderstorm development. 00z NAM suggests strong boundary-layer heating will be noted into this feature which will result in convective temperatures being breached by 20-21z. Will maintain 5% severe probs across this region due to the expected isolated nature of convection. ..Darrow/Cook.. 08/13/2019 Read more