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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Wed Sep 11 2019 Valid 112000Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PARTS OF SOUTHEAST WYOMING...NORTHEAST COLORADO...AND WESTERN NEBRASKA.... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHERN WISCONSIN AND CENTRAL/SOUTHERN LOWER MICHIGAN... ...SUMMARY... Severe thunderstorms are expected over parts of the central High Plains, where large hail, damaging wind gusts and a few tornadoes are possible. Other severe storms may also affect portions of Wisconsin and Lower Michigan. ...20Z Update... ...High Plains... Forecast outlined in the previous forecast discussion (appended below) remains valid. Buoyancy continues to build as the air mass destabilizes and storms are expected to initiate by 21-22Z as the upper trough approaches. Additional information about this region is available in MCD 1958. ...WI/MI... Severe Thunderstorm Watch 645 remains in effect across central/southern Lower MI and southern WI until 03Z. Primary threats include scattered damaging wind gusts to 70 mph and isolated large hail. ...OH/PA into Mid-Atlantic States... Thunderstorm coverage is beginning to increase along the northeastern periphery of the large surface high centered over middle TN/northern AL. Mid-level flow is generally weak and overall storm strength and organization is expected to remain marginal. More information about the area is available in MCD 1957. ..Mosier.. 09/11/2019 .PREV DISCUSSION... /ISSUED 1122 AM CDT Wed Sep 11 2019/ ...High Plains... An upper trough over the western states will move slowly eastward today, with midlevel height falls and lift over the High Plains this afternoon and evening. Visible satellite imagery shows persistent low clouds over eastern WY/northeast CO/NE Panhandle, where easterly low-level winds and ample moisture are present. Current indications are that these clouds will burn off by mid-afternoon, allowing rapid destabilization and convective initiation. Other storms are likely to form along the eastern edge of the low clouds over northwest KS and southwest NE where strong heating will continue. All of this activity will be is environment of sufficient deep-layer shear for supercell structures. Large to very large hail will be the main threat through much of the afternoon and early evening, although an isolated tornado or two is possible with the more persistent supercells. As the low-level jet strengthen this evening, a more focused damaging wind threat may evolve over NE. ...WI/MI... A remnant MCV/shortwave trough is moving across western WI this morning. Strong heating ahead of the feature over southeast WI and southern Lower MI should aid in the re-development of scattered strong to severe storms my early afternoon. Forecast soundings show sufficient CAPE and mid level wind fields to promote damaging winds and some hail in the strongest cells. A few supercells are also possible - especially across central Lower MI in the vicinity of a weak surface boundary. Storms will track southeastward through the early evening before weakening. ...Western KS into TX Panhandle... Isolated strong thunderstorms will be possible once again today along the surface dryline over western KS and parts of the OK/TX Panhandles. Gusty winds and some hail will be possible for a few hours this afternoon and evening. ...OH/PA into Mid-Atlantic States... Strong heating and ample low level moisture will promote moderate CAPE values over parts of eastern OH, much of PA, and southward along an axis into parts of VA/NC. Scattered thunderstorms will affect this region, with a few of the storms posing a transient risk of gusty/damaging winds. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Wed Sep 11 2019 Valid 112000Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PARTS OF SOUTHEAST WYOMING...NORTHEAST COLORADO...AND WESTERN NEBRASKA.... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHERN WISCONSIN AND CENTRAL/SOUTHERN LOWER MICHIGAN... ...SUMMARY... Severe thunderstorms are expected over parts of the central High Plains, where large hail, damaging wind gusts and a few tornadoes are possible. Other severe storms may also affect portions of Wisconsin and Lower Michigan. ...20Z Update... ...High Plains... Forecast outlined in the previous forecast discussion (appended below) remains valid. Buoyancy continues to build as the air mass destabilizes and storms are expected to initiate by 21-22Z as the upper trough approaches. Additional information about this region is available in MCD 1958. ...WI/MI... Severe Thunderstorm Watch 645 remains in effect across central/southern Lower MI and southern WI until 03Z. Primary threats include scattered damaging wind gusts to 70 mph and isolated large hail. ...OH/PA into Mid-Atlantic States... Thunderstorm coverage is beginning to increase along the northeastern periphery of the large surface high centered over middle TN/northern AL. Mid-level flow is generally weak and overall storm strength and organization is expected to remain marginal. More information about the area is available in MCD 1957. ..Mosier.. 09/11/2019 .PREV DISCUSSION... /ISSUED 1122 AM CDT Wed Sep 11 2019/ ...High Plains... An upper trough over the western states will move slowly eastward today, with midlevel height falls and lift over the High Plains this afternoon and evening. Visible satellite imagery shows persistent low clouds over eastern WY/northeast CO/NE Panhandle, where easterly low-level winds and ample moisture are present. Current indications are that these clouds will burn off by mid-afternoon, allowing rapid destabilization and convective initiation. Other storms are likely to form along the eastern edge of the low clouds over northwest KS and southwest NE where strong heating will continue. All of this activity will be is environment of sufficient deep-layer shear for supercell structures. Large to very large hail will be the main threat through much of the afternoon and early evening, although an isolated tornado or two is possible with the more persistent supercells. As the low-level jet strengthen this evening, a more focused damaging wind threat may evolve over NE. ...WI/MI... A remnant MCV/shortwave trough is moving across western WI this morning. Strong heating ahead of the feature over southeast WI and southern Lower MI should aid in the re-development of scattered strong to severe storms my early afternoon. Forecast soundings show sufficient CAPE and mid level wind fields to promote damaging winds and some hail in the strongest cells. A few supercells are also possible - especially across central Lower MI in the vicinity of a weak surface boundary. Storms will track southeastward through the early evening before weakening. ...Western KS into TX Panhandle... Isolated strong thunderstorms will be possible once again today along the surface dryline over western KS and parts of the OK/TX Panhandles. Gusty winds and some hail will be possible for a few hours this afternoon and evening. ...OH/PA into Mid-Atlantic States... Strong heating and ample low level moisture will promote moderate CAPE values over parts of eastern OH, much of PA, and southward along an axis into parts of VA/NC. Scattered thunderstorms will affect this region, with a few of the storms posing a transient risk of gusty/damaging winds. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Wed Sep 11 2019 Valid 112000Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PARTS OF SOUTHEAST WYOMING...NORTHEAST COLORADO...AND WESTERN NEBRASKA.... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHERN WISCONSIN AND CENTRAL/SOUTHERN LOWER MICHIGAN... ...SUMMARY... Severe thunderstorms are expected over parts of the central High Plains, where large hail, damaging wind gusts and a few tornadoes are possible. Other severe storms may also affect portions of Wisconsin and Lower Michigan. ...20Z Update... ...High Plains... Forecast outlined in the previous forecast discussion (appended below) remains valid. Buoyancy continues to build as the air mass destabilizes and storms are expected to initiate by 21-22Z as the upper trough approaches. Additional information about this region is available in MCD 1958. ...WI/MI... Severe Thunderstorm Watch 645 remains in effect across central/southern Lower MI and southern WI until 03Z. Primary threats include scattered damaging wind gusts to 70 mph and isolated large hail. ...OH/PA into Mid-Atlantic States... Thunderstorm coverage is beginning to increase along the northeastern periphery of the large surface high centered over middle TN/northern AL. Mid-level flow is generally weak and overall storm strength and organization is expected to remain marginal. More information about the area is available in MCD 1957. ..Mosier.. 09/11/2019 .PREV DISCUSSION... /ISSUED 1122 AM CDT Wed Sep 11 2019/ ...High Plains... An upper trough over the western states will move slowly eastward today, with midlevel height falls and lift over the High Plains this afternoon and evening. Visible satellite imagery shows persistent low clouds over eastern WY/northeast CO/NE Panhandle, where easterly low-level winds and ample moisture are present. Current indications are that these clouds will burn off by mid-afternoon, allowing rapid destabilization and convective initiation. Other storms are likely to form along the eastern edge of the low clouds over northwest KS and southwest NE where strong heating will continue. All of this activity will be is environment of sufficient deep-layer shear for supercell structures. Large to very large hail will be the main threat through much of the afternoon and early evening, although an isolated tornado or two is possible with the more persistent supercells. As the low-level jet strengthen this evening, a more focused damaging wind threat may evolve over NE. ...WI/MI... A remnant MCV/shortwave trough is moving across western WI this morning. Strong heating ahead of the feature over southeast WI and southern Lower MI should aid in the re-development of scattered strong to severe storms my early afternoon. Forecast soundings show sufficient CAPE and mid level wind fields to promote damaging winds and some hail in the strongest cells. A few supercells are also possible - especially across central Lower MI in the vicinity of a weak surface boundary. Storms will track southeastward through the early evening before weakening. ...Western KS into TX Panhandle... Isolated strong thunderstorms will be possible once again today along the surface dryline over western KS and parts of the OK/TX Panhandles. Gusty winds and some hail will be possible for a few hours this afternoon and evening. ...OH/PA into Mid-Atlantic States... Strong heating and ample low level moisture will promote moderate CAPE values over parts of eastern OH, much of PA, and southward along an axis into parts of VA/NC. Scattered thunderstorms will affect this region, with a few of the storms posing a transient risk of gusty/damaging winds. Read more

MD 1958 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF WESTERN/CENTRAL NE...NORTHEAST CO AND NORTHWEST KS
Mesoscale Discussion 1958 NWS Storm Prediction Center Norman OK 0228 PM CDT Wed Sep 11 2019 Areas affected...portions of western/central NE...northeast CO and northwest KS Concerning...Severe potential...Watch likely Valid 111928Z - 112100Z Probability of Watch Issuance...80 percent SUMMARY...The severe threat will continue to increase from northeast CO into southwest and central NE and far northwest KS. A watch will likely be needed by 21z. DISCUSSION...Early day cloud cover across parts of western NE and northeast CO has eroded and temperatures are quickly climbing into the 70s to near 80 F early this afternoon. Further east, where strong heating has occurred, temperatures were in the mid to upper 80s. Surface dew points increase from the low 60s to the mid/upper 60s west to east from southwest NE/northeast CO eastward toward central NE/KS. This is resulting in rapid destabilization, with MLCAPE now ranging from 1000-2500 J/kg. Isolated CU is forming across the area in response, and guidance has consistently indicated storm initiation by 21z. This may be a little ambitious due to stronger capping associated with earlier cloud cover, but certainly expect storms in the 21-23z time frame. Strong vertical wind profiles will be supportive of supercells and steep midlevel lapse rates will favor large hail, some possible larger than 2 inches in diameter. Region VWP data also shows backed low level flow through about 2 km, resulting in curved low level hodographs. As storms move into deeper moisture across NE/KS this could result in a couple of tornadoes, especially across southwest into central NE where a surface boundary will further increase 0-1 km SRH. During the evening, a southerly low level jet will increase and storms may grow upscale into one or more bowing clusters. Trends will continue to be monitored and a watch will likely be needed by 21z. ..Leitman/Hart.. 09/11/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GID...LBF...GLD...BOU...CYS... LAT...LON 40260336 41380299 41960271 42340199 42550088 42540017 42389951 42109922 41659905 41099920 40289968 39500042 39200119 39120184 39120260 39300317 39660340 40260336 Read more

WW 0645 Status Updates
STATUS REPORT ON WW 645 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..WENDT..09/11/19 ATTN...WFO...GRR...DTX...MKX... STATUS REPORT FOR WS 645 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MIC005-015-017-025-035-037-045-049-057-063-065-067-073-075-077- 081-085-087-091-093-099-105-107-111-115-117-121-123-125-127-133- 139-145-147-151-155-157-159-161-163-112040- MI . MICHIGAN COUNTIES INCLUDED ARE ALLEGAN BARRY BAY CALHOUN CLARE CLINTON EATON GENESEE GRATIOT HURON INGHAM IONIA ISABELLA JACKSON KALAMAZOO KENT LAKE LAPEER LENAWEE LIVINGSTON MACOMB MASON MECOSTA MIDLAND MONROE MONTCALM MUSKEGON NEWAYGO OAKLAND OCEANA OSCEOLA OTTAWA SAGINAW ST. CLAIR SANILAC SHIAWASSEE TUSCOLA VAN BUREN WASHTENAW WAYNE WIC021-025-027-045-049-055-059-065-079-089-101-105-111-127-131- 133-112040- Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0216 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z The ongoing forecast is generally on track. Great Basin high pressure will contribute to a strong offshore pressure gradient across southern California early D2/Thursday morning. Gusty easterly/northeasterly surface winds will result, with isolated gusts to 35 mph especially in terrain-favored areas. This gradient should slacken some during the day before strengthening again overnight Thursday into Friday morning. Meanwhile, gusts will occur amidst 25-35% RH values, further supporting elevated fire weather. See the previous discussion below for more details. ..Cook.. 09/11/2019 .PREV DISCUSSION... /ISSUED 0156 AM CDT Wed Sep 11 2019/ ...Synopsis... As the first in a series of mid-level shortwaves ejects into the Plains, a second, smaller mid-level impulse will traverse the Pacific Northwest during the Day 2/Thursday period. Otherwise, weak zonal flow aloft will prevail across the remainder of the western CONUS. A modest surface pressure gradient however, may become established across parts of southern California, encouraging dry offshore flow across the higher terrain near the southwest California coastline. ...Southern Coastal California... With the modest aforementioned pressure gradient in place across the area, elevated surface wind/RH conditions (15-20 mph east-northeasterly flow with 15-20% RH) are expected to transpire by late afternoon and continue into the overnight hours, towards the end of the period. These conditions will especially prevail along the higher terrain, from the San Gabriel to San Jacinto Mountains, where lack of rainfall and dry fuels will support at least marginal wildfire-spread potential, warranting an elevated delineation. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0216 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z The ongoing forecast is generally on track. Great Basin high pressure will contribute to a strong offshore pressure gradient across southern California early D2/Thursday morning. Gusty easterly/northeasterly surface winds will result, with isolated gusts to 35 mph especially in terrain-favored areas. This gradient should slacken some during the day before strengthening again overnight Thursday into Friday morning. Meanwhile, gusts will occur amidst 25-35% RH values, further supporting elevated fire weather. See the previous discussion below for more details. ..Cook.. 09/11/2019 .PREV DISCUSSION... /ISSUED 0156 AM CDT Wed Sep 11 2019/ ...Synopsis... As the first in a series of mid-level shortwaves ejects into the Plains, a second, smaller mid-level impulse will traverse the Pacific Northwest during the Day 2/Thursday period. Otherwise, weak zonal flow aloft will prevail across the remainder of the western CONUS. A modest surface pressure gradient however, may become established across parts of southern California, encouraging dry offshore flow across the higher terrain near the southwest California coastline. ...Southern Coastal California... With the modest aforementioned pressure gradient in place across the area, elevated surface wind/RH conditions (15-20 mph east-northeasterly flow with 15-20% RH) are expected to transpire by late afternoon and continue into the overnight hours, towards the end of the period. These conditions will especially prevail along the higher terrain, from the San Gabriel to San Jacinto Mountains, where lack of rainfall and dry fuels will support at least marginal wildfire-spread potential, warranting an elevated delineation. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0216 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z The ongoing forecast is generally on track. Great Basin high pressure will contribute to a strong offshore pressure gradient across southern California early D2/Thursday morning. Gusty easterly/northeasterly surface winds will result, with isolated gusts to 35 mph especially in terrain-favored areas. This gradient should slacken some during the day before strengthening again overnight Thursday into Friday morning. Meanwhile, gusts will occur amidst 25-35% RH values, further supporting elevated fire weather. See the previous discussion below for more details. ..Cook.. 09/11/2019 .PREV DISCUSSION... /ISSUED 0156 AM CDT Wed Sep 11 2019/ ...Synopsis... As the first in a series of mid-level shortwaves ejects into the Plains, a second, smaller mid-level impulse will traverse the Pacific Northwest during the Day 2/Thursday period. Otherwise, weak zonal flow aloft will prevail across the remainder of the western CONUS. A modest surface pressure gradient however, may become established across parts of southern California, encouraging dry offshore flow across the higher terrain near the southwest California coastline. ...Southern Coastal California... With the modest aforementioned pressure gradient in place across the area, elevated surface wind/RH conditions (15-20 mph east-northeasterly flow with 15-20% RH) are expected to transpire by late afternoon and continue into the overnight hours, towards the end of the period. These conditions will especially prevail along the higher terrain, from the San Gabriel to San Jacinto Mountains, where lack of rainfall and dry fuels will support at least marginal wildfire-spread potential, warranting an elevated delineation. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0216 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z The ongoing forecast is generally on track. Great Basin high pressure will contribute to a strong offshore pressure gradient across southern California early D2/Thursday morning. Gusty easterly/northeasterly surface winds will result, with isolated gusts to 35 mph especially in terrain-favored areas. This gradient should slacken some during the day before strengthening again overnight Thursday into Friday morning. Meanwhile, gusts will occur amidst 25-35% RH values, further supporting elevated fire weather. See the previous discussion below for more details. ..Cook.. 09/11/2019 .PREV DISCUSSION... /ISSUED 0156 AM CDT Wed Sep 11 2019/ ...Synopsis... As the first in a series of mid-level shortwaves ejects into the Plains, a second, smaller mid-level impulse will traverse the Pacific Northwest during the Day 2/Thursday period. Otherwise, weak zonal flow aloft will prevail across the remainder of the western CONUS. A modest surface pressure gradient however, may become established across parts of southern California, encouraging dry offshore flow across the higher terrain near the southwest California coastline. ...Southern Coastal California... With the modest aforementioned pressure gradient in place across the area, elevated surface wind/RH conditions (15-20 mph east-northeasterly flow with 15-20% RH) are expected to transpire by late afternoon and continue into the overnight hours, towards the end of the period. These conditions will especially prevail along the higher terrain, from the San Gabriel to San Jacinto Mountains, where lack of rainfall and dry fuels will support at least marginal wildfire-spread potential, warranting an elevated delineation. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1957 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR FAR EASTERN OHIO...WESTERN/CENTRAL PENNSYLVANIA...PORTIONS OF MID-ATLANTIC
Mesoscale Discussion 1957 NWS Storm Prediction Center Norman OK 0208 PM CDT Wed Sep 11 2019 Areas affected...Far eastern Ohio...western/central Pennsylvania...Portions of Mid-Atlantic Concerning...Severe potential...Watch unlikely Valid 111908Z - 112115Z Probability of Watch Issuance...20 percent SUMMARY...Isolated wind damage from water-loaded downbursts possible this afternoon. No WW is planned. DISCUSSION...Strong daytime heating of very moist airmass has lead to the development of a few clusters of storms in eastern Ohio and along the Blue Ridge. So far, convection has remained generally shallow; however, storm intensity will likely increase as temperatures across the region warm into the upper-80s and low-90s F. Deep-layer flow is uniformly weak meaning storms will be only loosely organized. The main threat from this activity will be wind damage from localized, water-loaded downdrafts as low-level lapse rates are quite steep. Any more organized threat from this activity would be conditional on cold pools merging and propagating eastward. Without upper-level support, this activity should wane at sunset and will not likely reach the coast given the stable marine layer pushing inland. No WW is planned. ..Wendt/Hart.. 09/11/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...BUF...CTP...LWX...RNK...PBZ...RLX... CLE... LAT...LON 40868144 41438119 42047995 41887810 41507719 40237636 39067628 38327656 37817692 37717737 37507793 37347868 37337932 37337985 37848020 38538011 39278020 39938058 40358111 40868144 Read more

No watches are valid as of Wed Sep 11 19:10:08 UTC 2019.

000
ABPZ20 KNHC 111749
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
Issued by the NWS Weather Prediction Center College Park MD
1100 AM PDT Wed Sep 11 2019

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

A broad area of low pressure located about 350 miles southwest of
Acapulco, Mexico, continues to become better defined. Environmental
conditions are conducive for further development, and a tropical
depression is expected to form in the next 24 hours as the
system moves westward to west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 5 days...high...90 percent.

Disorganized showers and thunderstorms centered about 1400 miles to
the southwest of the southern tip of the Baja California peninsula
are associated with a tropical wave. Some slow development is
possible during the next few days while the system moves slowly
westward at 5 to 10 mph.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...low...30 percent.

An area of low pressure is expected to form west of the coast of
Cental America over the weekend. Thereafter, some development is
possible into early next week while the system moves westward at
about 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

$$
Forecaster Burke/Blake

MD 1956 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF SOUTHERN WISCONSIN AND SOUTHERN LOWER MICHIGAN
Mesoscale Discussion 1956 NWS Storm Prediction Center Norman OK 1248 PM CDT Wed Sep 11 2019 Areas affected...Portions of southern Wisconsin and southern Lower Michigan Concerning...Severe potential...Watch possible Valid 111748Z - 111945Z Probability of Watch Issuance...60 percent SUMMARY...Convective coverage along a cold front in central Wisconsin and central Lower Michigan will increase in the next two hours. Damaging winds will the the primary threat with marginally severe hail and an isolated tornado possible. A WW is possible in the next hour or two. DISCUSSION...Mid-level ascent continues to increase across southern Wisconsin and southern Lower Michigan with the approach of a shortwave trough. Despite cloud cover across Wisconsin, 1-minute visible satellite imagery shows increasing agitated cumulus along the cold front with convection also increasing in central Lower Michigan where surface heating has been stronger. 1500-2000 J/kg MLCAPE will exist this afternoon in areas that have remained relatively cloud free. Stronger convection is likely to occur in Wisconsin with the better upper-level support, though stronger surface heating in Michigan may allow more isolated activity to develop prior to the shortwave arriving. Given deep-layer shear (effectively 30-40 kts) parallel to the boundary, congealing cold pools and upscale growth is likely to occur quickly making damaging winds the primary threat. Marginally severe hail may occur in stronger cells, but modest mid-level lapse rates should keep coverage of larger hail minimal. While the risk of a tornado will remain low, a 30 kt 850 mb jet moving through the area will enlarge low-level hodographs enough that an isolated tornado may occur early in the convective cycle before upscale growth/storm interactions. With time, the convection will reinforce the cold front and the boundary will sag southward. Given the expected storm coverage and potential for damaging wind gusts, a WW is possible within the next hour or two. ..Wendt/Hart.. 09/11/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CLE...DTX...IWX...GRR...GRB...LOT...MKX...DVN... ARX... LAT...LON 43039028 43498999 44038699 43348387 42748262 41758326 41508379 41898659 42148875 42409000 43039028 Read more

MD 1955 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR EASTERN WY INTO FAR WESTERN NE AND NORTH-CENTRAL CO
Mesoscale Discussion 1955 NWS Storm Prediction Center Norman OK 1228 PM CDT Wed Sep 11 2019 Areas affected...eastern WY into far western NE and north-central CO Concerning...Severe potential...Watch likely Valid 111728Z - 111930Z Probability of Watch Issuance...80 percent SUMMARY...Thunderstorms will increase in coverage and intensity over the next couple of hours. All severe hazards will be possible (large hail, damaging gusts and a couple of tornadoes) and a watch is expected in the next 1-2 hours. DISCUSSION...Modest destabilization is occurring across eastern WY/CO into the central Plains at midday. Low level stratus over far eastern WY into the NE Panhandle and northeast CO is slowly eroding and this trend is expected to continue through the afternoon. However, this cloud cover may limit convective initiation/eastward progression of thunderstorms until later this afternoon into the evening. In the near-term, a more confined severe threat is expected mainly across eastern WY and perhaps into far north-central CO. Stronger forcing for ascent associated with a shortwave impulse lifting northeast across the Great Basin is now ejecting into western WY/northwest CO as indicated by WV imagery and an increase in thunderstorms developing across the higher terrain of south-central WY into far north-central CO. As stronger heating occurs across this region in broken mid/upper level cloudiness, MLCAPE should increase to 500-1500 J/kg by 19-20z. 12z regional RAOBs show steep midlevel lapse rates across the region ranging from 7.5-8.5 C/km in the presence of strong shear supportive of rotating updrafts. This will result in a threat for large (some greater than 2 inches) hail. Dew points across eastern WY are generally in the low to mid 50s with higher quality moisture existing well to the east. Nevertheless, backed low level winds and low LCLs for this region could be sufficient for a couple of tornadoes, mainly across southeast WY. Fast storm motion also will aid in damaging wind potential. Given a more meridional and unidirectional component to vertical winds above around 2 km, some bowing segments/clusters also will be possible in addition to more discrete convection. A watch will likely be needed for portions of the MCD area in the next 1-2 hours. ..Leitman/Hart.. 09/11/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...BOU...CYS...BYZ...RIW... LAT...LON 41360335 42380329 43020351 43740394 44730481 44920559 44680618 42420709 41640726 41100690 40580619 40440520 40570425 41360335 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER MS VALLEY SOUTHWESTWARD INTO SOUTHEAST KS... ...SUMMARY... Strong to severe thunderstorms are possible on Thursday from southern Plains north-northeastward into the Upper Mississippi Valley. A few storms capable of damaging wind gusts are also anticipated over the northern Mid-Atlantic States. ...Synopsis... A shortwave trough extending across the northern and central High Plains early Thursday morning is expected to deepen/mature as it moves northeastward across the northern/central Plains and into the Upper Midwest. Enhanced southwesterly flow aloft accompanying this shortwave will spread northeastward just ahead of it into the Upper Midwest while the deepening/maturing of the overall system strengthens mid-level flow throughout its southern periphery. By early Friday morning, enhanced mid-level is expected from the Dakotas and Nebraska eastward/northeastward into the Upper Great Lakes. At the surface, the low associated with the maturing shortwave trough will follow a similar deepening/maturing trend as it moves north-northeastward from near the NE/SD/IA border intersection into north-central MN. A cold front attendant to this low will sweep quickly across the central/southern Plains and mid/upper MS Valley. By early Friday morning, this cold front will likely extend from southern WI southwestward into the southern TX Panhandle. ...Upper/Mid MS Valley...Central/Southern Plains... Numerous showers and thunderstorms will likely be ongoing at the beginning of the period across IA and MN. These showers and thunderstorms will be the remnant of an overnight MCS over NE/SD combined with warm-air advection activity near the MCS outflow and the warm front associated with the larger mid-latitude cyclone. Expectation is for these storms to move northeastward, gradually dissipating amidst limited buoyancy and displacement from the low-level jet. Destabilization in the wake of this activity across southern MN and IA is somewhat uncertain. Current expectation is for ample low-level moisture to remain in place south of the warm front, despite this early morning activity. As such, the air mass appears it will support another round of thunderstorms along the front (which will lag behind the early morning storms) from south-central MN southwestward into the southern Plains. The strongest forcing for ascent and vertical shear will be near the developing mid-level low across the mid MO Valley and Upper Midwest. Much of that region will be cool, cloudy, and stable. However, instability is expected to remain south of the warm front, which is expected to extend from the surface low over the eastern SD/ND border southeastward across central MN, southern WI, and into the upper OH Valley on Thursday afternoon. As such, the best overlap between vertical shear and instability is anticipated from south-central MN across central IA into northern MO. A few more organized storms are possible in this region, although the lingering questions regarding destabilization introduces some uncertainty regarding overall updraft strength and the resulting severe potential. Strong diurnal heating and ample low-level moisture will support moderate buoyancy farther southwest along the front into the TX Panhandle. Thunderstorms are expected to develop along the length of this boundary with occasional strong wind gusts and hail possible. Limited vertical shear should limit overall updraft strength/organization. ...Northern Mid-Atlantic States... Cold front associated with a shortwave trough and attendant surface low well to the northeast over the northern Atlantic will move southward across the northern Mid-Atlantic States on Thursday. This area will be on the southern edge of the better northwesterly flow aloft and thunderstorms developing along front may experience modest organization due to the increased vertical shear. Instability will be modest but the resulting line segments may occasionally produce damaging wind gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 09/11/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER MS VALLEY SOUTHWESTWARD INTO SOUTHEAST KS... ...SUMMARY... Strong to severe thunderstorms are possible on Thursday from southern Plains north-northeastward into the Upper Mississippi Valley. A few storms capable of damaging wind gusts are also anticipated over the northern Mid-Atlantic States. ...Synopsis... A shortwave trough extending across the northern and central High Plains early Thursday morning is expected to deepen/mature as it moves northeastward across the northern/central Plains and into the Upper Midwest. Enhanced southwesterly flow aloft accompanying this shortwave will spread northeastward just ahead of it into the Upper Midwest while the deepening/maturing of the overall system strengthens mid-level flow throughout its southern periphery. By early Friday morning, enhanced mid-level is expected from the Dakotas and Nebraska eastward/northeastward into the Upper Great Lakes. At the surface, the low associated with the maturing shortwave trough will follow a similar deepening/maturing trend as it moves north-northeastward from near the NE/SD/IA border intersection into north-central MN. A cold front attendant to this low will sweep quickly across the central/southern Plains and mid/upper MS Valley. By early Friday morning, this cold front will likely extend from southern WI southwestward into the southern TX Panhandle. ...Upper/Mid MS Valley...Central/Southern Plains... Numerous showers and thunderstorms will likely be ongoing at the beginning of the period across IA and MN. These showers and thunderstorms will be the remnant of an overnight MCS over NE/SD combined with warm-air advection activity near the MCS outflow and the warm front associated with the larger mid-latitude cyclone. Expectation is for these storms to move northeastward, gradually dissipating amidst limited buoyancy and displacement from the low-level jet. Destabilization in the wake of this activity across southern MN and IA is somewhat uncertain. Current expectation is for ample low-level moisture to remain in place south of the warm front, despite this early morning activity. As such, the air mass appears it will support another round of thunderstorms along the front (which will lag behind the early morning storms) from south-central MN southwestward into the southern Plains. The strongest forcing for ascent and vertical shear will be near the developing mid-level low across the mid MO Valley and Upper Midwest. Much of that region will be cool, cloudy, and stable. However, instability is expected to remain south of the warm front, which is expected to extend from the surface low over the eastern SD/ND border southeastward across central MN, southern WI, and into the upper OH Valley on Thursday afternoon. As such, the best overlap between vertical shear and instability is anticipated from south-central MN across central IA into northern MO. A few more organized storms are possible in this region, although the lingering questions regarding destabilization introduces some uncertainty regarding overall updraft strength and the resulting severe potential. Strong diurnal heating and ample low-level moisture will support moderate buoyancy farther southwest along the front into the TX Panhandle. Thunderstorms are expected to develop along the length of this boundary with occasional strong wind gusts and hail possible. Limited vertical shear should limit overall updraft strength/organization. ...Northern Mid-Atlantic States... Cold front associated with a shortwave trough and attendant surface low well to the northeast over the northern Atlantic will move southward across the northern Mid-Atlantic States on Thursday. This area will be on the southern edge of the better northwesterly flow aloft and thunderstorms developing along front may experience modest organization due to the increased vertical shear. Instability will be modest but the resulting line segments may occasionally produce damaging wind gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 09/11/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER MS VALLEY SOUTHWESTWARD INTO SOUTHEAST KS... ...SUMMARY... Strong to severe thunderstorms are possible on Thursday from southern Plains north-northeastward into the Upper Mississippi Valley. A few storms capable of damaging wind gusts are also anticipated over the northern Mid-Atlantic States. ...Synopsis... A shortwave trough extending across the northern and central High Plains early Thursday morning is expected to deepen/mature as it moves northeastward across the northern/central Plains and into the Upper Midwest. Enhanced southwesterly flow aloft accompanying this shortwave will spread northeastward just ahead of it into the Upper Midwest while the deepening/maturing of the overall system strengthens mid-level flow throughout its southern periphery. By early Friday morning, enhanced mid-level is expected from the Dakotas and Nebraska eastward/northeastward into the Upper Great Lakes. At the surface, the low associated with the maturing shortwave trough will follow a similar deepening/maturing trend as it moves north-northeastward from near the NE/SD/IA border intersection into north-central MN. A cold front attendant to this low will sweep quickly across the central/southern Plains and mid/upper MS Valley. By early Friday morning, this cold front will likely extend from southern WI southwestward into the southern TX Panhandle. ...Upper/Mid MS Valley...Central/Southern Plains... Numerous showers and thunderstorms will likely be ongoing at the beginning of the period across IA and MN. These showers and thunderstorms will be the remnant of an overnight MCS over NE/SD combined with warm-air advection activity near the MCS outflow and the warm front associated with the larger mid-latitude cyclone. Expectation is for these storms to move northeastward, gradually dissipating amidst limited buoyancy and displacement from the low-level jet. Destabilization in the wake of this activity across southern MN and IA is somewhat uncertain. Current expectation is for ample low-level moisture to remain in place south of the warm front, despite this early morning activity. As such, the air mass appears it will support another round of thunderstorms along the front (which will lag behind the early morning storms) from south-central MN southwestward into the southern Plains. The strongest forcing for ascent and vertical shear will be near the developing mid-level low across the mid MO Valley and Upper Midwest. Much of that region will be cool, cloudy, and stable. However, instability is expected to remain south of the warm front, which is expected to extend from the surface low over the eastern SD/ND border southeastward across central MN, southern WI, and into the upper OH Valley on Thursday afternoon. As such, the best overlap between vertical shear and instability is anticipated from south-central MN across central IA into northern MO. A few more organized storms are possible in this region, although the lingering questions regarding destabilization introduces some uncertainty regarding overall updraft strength and the resulting severe potential. Strong diurnal heating and ample low-level moisture will support moderate buoyancy farther southwest along the front into the TX Panhandle. Thunderstorms are expected to develop along the length of this boundary with occasional strong wind gusts and hail possible. Limited vertical shear should limit overall updraft strength/organization. ...Northern Mid-Atlantic States... Cold front associated with a shortwave trough and attendant surface low well to the northeast over the northern Atlantic will move southward across the northern Mid-Atlantic States on Thursday. This area will be on the southern edge of the better northwesterly flow aloft and thunderstorms developing along front may experience modest organization due to the increased vertical shear. Instability will be modest but the resulting line segments may occasionally produce damaging wind gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 09/11/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER MS VALLEY SOUTHWESTWARD INTO SOUTHEAST KS... ...SUMMARY... Strong to severe thunderstorms are possible on Thursday from southern Plains north-northeastward into the Upper Mississippi Valley. A few storms capable of damaging wind gusts are also anticipated over the northern Mid-Atlantic States. ...Synopsis... A shortwave trough extending across the northern and central High Plains early Thursday morning is expected to deepen/mature as it moves northeastward across the northern/central Plains and into the Upper Midwest. Enhanced southwesterly flow aloft accompanying this shortwave will spread northeastward just ahead of it into the Upper Midwest while the deepening/maturing of the overall system strengthens mid-level flow throughout its southern periphery. By early Friday morning, enhanced mid-level is expected from the Dakotas and Nebraska eastward/northeastward into the Upper Great Lakes. At the surface, the low associated with the maturing shortwave trough will follow a similar deepening/maturing trend as it moves north-northeastward from near the NE/SD/IA border intersection into north-central MN. A cold front attendant to this low will sweep quickly across the central/southern Plains and mid/upper MS Valley. By early Friday morning, this cold front will likely extend from southern WI southwestward into the southern TX Panhandle. ...Upper/Mid MS Valley...Central/Southern Plains... Numerous showers and thunderstorms will likely be ongoing at the beginning of the period across IA and MN. These showers and thunderstorms will be the remnant of an overnight MCS over NE/SD combined with warm-air advection activity near the MCS outflow and the warm front associated with the larger mid-latitude cyclone. Expectation is for these storms to move northeastward, gradually dissipating amidst limited buoyancy and displacement from the low-level jet. Destabilization in the wake of this activity across southern MN and IA is somewhat uncertain. Current expectation is for ample low-level moisture to remain in place south of the warm front, despite this early morning activity. As such, the air mass appears it will support another round of thunderstorms along the front (which will lag behind the early morning storms) from south-central MN southwestward into the southern Plains. The strongest forcing for ascent and vertical shear will be near the developing mid-level low across the mid MO Valley and Upper Midwest. Much of that region will be cool, cloudy, and stable. However, instability is expected to remain south of the warm front, which is expected to extend from the surface low over the eastern SD/ND border southeastward across central MN, southern WI, and into the upper OH Valley on Thursday afternoon. As such, the best overlap between vertical shear and instability is anticipated from south-central MN across central IA into northern MO. A few more organized storms are possible in this region, although the lingering questions regarding destabilization introduces some uncertainty regarding overall updraft strength and the resulting severe potential. Strong diurnal heating and ample low-level moisture will support moderate buoyancy farther southwest along the front into the TX Panhandle. Thunderstorms are expected to develop along the length of this boundary with occasional strong wind gusts and hail possible. Limited vertical shear should limit overall updraft strength/organization. ...Northern Mid-Atlantic States... Cold front associated with a shortwave trough and attendant surface low well to the northeast over the northern Atlantic will move southward across the northern Mid-Atlantic States on Thursday. This area will be on the southern edge of the better northwesterly flow aloft and thunderstorms developing along front may experience modest organization due to the increased vertical shear. Instability will be modest but the resulting line segments may occasionally produce damaging wind gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 09/11/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Wed Sep 11 2019 Valid 121200Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER MS VALLEY SOUTHWESTWARD INTO SOUTHEAST KS... ...SUMMARY... Strong to severe thunderstorms are possible on Thursday from southern Plains north-northeastward into the Upper Mississippi Valley. A few storms capable of damaging wind gusts are also anticipated over the northern Mid-Atlantic States. ...Synopsis... A shortwave trough extending across the northern and central High Plains early Thursday morning is expected to deepen/mature as it moves northeastward across the northern/central Plains and into the Upper Midwest. Enhanced southwesterly flow aloft accompanying this shortwave will spread northeastward just ahead of it into the Upper Midwest while the deepening/maturing of the overall system strengthens mid-level flow throughout its southern periphery. By early Friday morning, enhanced mid-level is expected from the Dakotas and Nebraska eastward/northeastward into the Upper Great Lakes. At the surface, the low associated with the maturing shortwave trough will follow a similar deepening/maturing trend as it moves north-northeastward from near the NE/SD/IA border intersection into north-central MN. A cold front attendant to this low will sweep quickly across the central/southern Plains and mid/upper MS Valley. By early Friday morning, this cold front will likely extend from southern WI southwestward into the southern TX Panhandle. ...Upper/Mid MS Valley...Central/Southern Plains... Numerous showers and thunderstorms will likely be ongoing at the beginning of the period across IA and MN. These showers and thunderstorms will be the remnant of an overnight MCS over NE/SD combined with warm-air advection activity near the MCS outflow and the warm front associated with the larger mid-latitude cyclone. Expectation is for these storms to move northeastward, gradually dissipating amidst limited buoyancy and displacement from the low-level jet. Destabilization in the wake of this activity across southern MN and IA is somewhat uncertain. Current expectation is for ample low-level moisture to remain in place south of the warm front, despite this early morning activity. As such, the air mass appears it will support another round of thunderstorms along the front (which will lag behind the early morning storms) from south-central MN southwestward into the southern Plains. The strongest forcing for ascent and vertical shear will be near the developing mid-level low across the mid MO Valley and Upper Midwest. Much of that region will be cool, cloudy, and stable. However, instability is expected to remain south of the warm front, which is expected to extend from the surface low over the eastern SD/ND border southeastward across central MN, southern WI, and into the upper OH Valley on Thursday afternoon. As such, the best overlap between vertical shear and instability is anticipated from south-central MN across central IA into northern MO. A few more organized storms are possible in this region, although the lingering questions regarding destabilization introduces some uncertainty regarding overall updraft strength and the resulting severe potential. Strong diurnal heating and ample low-level moisture will support moderate buoyancy farther southwest along the front into the TX Panhandle. Thunderstorms are expected to develop along the length of this boundary with occasional strong wind gusts and hail possible. Limited vertical shear should limit overall updraft strength/organization. ...Northern Mid-Atlantic States... Cold front associated with a shortwave trough and attendant surface low well to the northeast over the northern Atlantic will move southward across the northern Mid-Atlantic States on Thursday. This area will be on the southern edge of the better northwesterly flow aloft and thunderstorms developing along front may experience modest organization due to the increased vertical shear. Instability will be modest but the resulting line segments may occasionally produce damaging wind gusts. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 09/11/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CDT Wed Sep 11 2019 Valid 111630Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PARTS OF SOUTHEAST WYOMING...NORTHEAST COLORADO...AND WESTERN NEBRASKA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHERN WISCONSIN AND CENTRAL/SOUTHERN LOWER MICHIGAN... ...SUMMARY... Severe thunderstorms are expected over parts of the central High Plains, where large hail, damaging wind gusts and a few tornadoes are possible. Other severe storms may also affect portions of Wisconsin and Lower Michigan. ...High Plains... An upper trough over the western states will move slowly eastward today, with midlevel height falls and lift over the High Plains this afternoon and evening. Visible satellite imagery shows persistent low clouds over eastern WY/northeast CO/NE Panhandle, where easterly low-level winds and ample moisture are present. Current indications are that these clouds will burn off by mid-afternoon, allowing rapid destabilization and convective initiation. Other storms are likely to form along the eastern edge of the low clouds over northwest KS and southwest NE where strong heating will continue. All of this activity will be is environment of sufficient deep-layer shear for supercell structures. Large to very large hail will be the main threat through much of the afternoon and early evening, although an isolated tornado or two is possible with the more persistent supercells. As the low-level jet strengthen this evening, a more focused damaging wind threat may evolve over NE. ...WI/MI... A remnant MCV/shortwave trough is moving across western WI this morning. Strong heating ahead of the feature over southeast WI and southern Lower MI should aid in the re-development of scattered strong to severe storms my early afternoon. Forecast soundings show sufficient CAPE and mid level wind fields to promote damaging winds and some hail in the strongest cells. A few supercells are also possible - especially across central Lower MI in the vicinity of a weak surface boundary. Storms will track southeastward through the early evening before weakening. ...Western KS into TX Panhandle... Isolated strong thunderstorms will be possible once again today along the surface dryline over western KS and parts of the OK/TX Panhandles. Gusty winds and some hail will be possible for a few hours this afternoon and evening. ...OH/PA into Mid-Atlantic States... Strong heating and ample low level moisture will promote moderate CAPE values over parts of eastern OH, much of PA, and southward along an axis into parts of VA/NC. Scattered thunderstorms will affect this region, with a few of the storms posing a transient risk of gusty/damaging winds. ..Hart/Wendt.. 09/11/2019 Read more