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WW 598 SEVERE TSTM IL IN MO 181805Z - 190000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 598 NWS Storm Prediction Center Norman OK 105 PM CDT Sun Aug 18 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern Illinois Central and southwest Indiana Southeast Missouri * Effective this Sunday afternoon and evening from 105 PM until 700 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Thunderstorms are expected to increase in coverage and intensity this afternoon from southeast Missouri into central Indiana, along a remnant outflow boundary. The storm environment across this corridor will favor multicell clusters capable of producing damaging winds and large hail through the afternoon. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 45 miles southwest of Farmington MO to 55 miles northeast of Indianapolis IN. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU8). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 27025. ...Thompson Read more

MD 1797 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTHWEST TEXAS AND SOUTHWEST OKLAHOMA
Mesoscale Discussion 1797 NWS Storm Prediction Center Norman OK 0620 PM CDT Sun Aug 18 2019 Areas affected...portions of northwest Texas and southwest Oklahoma Concerning...Severe potential...Watch unlikely Valid 182320Z - 190145Z Probability of Watch Issuance...5 percent SUMMARY...Storms are developing across northwest Texas and will likely develop into southwest Oklahoma with isolated damaging wind gusts possible this evening. DISCUSSION...Storms have developed along a quasi-dryline and near a surface low in northwest Texas/vicinity with surface temperatures exceeding 100 F across the area helping to breach convective temperatures. Deep boundary layer mixing has lead to high LCLs and a dry sub-cloud layer with DCAPE values over 1500+ J/kg per mesoanalysis. Additionally, MLCAPE of 1000-3000 J/kg will lead to mature thunderstorms with transient supercell structures possible given the 25-40 knots of effective bulk shear. While the environment does not appear as favorable as last night, isolated damaging wind gusts are possible with these storms across northwest Texas and southwest Oklahoma. Some continuation and upscale growth after sunset is possible as the low-level jet is forecast to strengthen somewhat across the southern High Plains. Given the isolated severe threat, a watch issuance is unlikely at this time. ..Nauslar/Guyer.. 08/18/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OUN...SJT...LUB...AMA...MAF... LAT...LON 32930007 32700072 32750141 32920154 34670113 35100045 35149995 35019894 34509891 34029894 33729899 33509907 33189950 33049991 32930007 Read more

000
ABPZ20 KNHC 182334
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 PM PDT Sun Aug 18 2019

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

An elongated area of low pressure located a couple of hundred miles
south of Guatemala and southeastern Mexico continues to produce
disorganized showers and thunderstorms. However, environmental
conditions are forecast to become more conducive for development
during the next couple of days, and a tropical depression is
expected to form by Tuesday or Wednesday while the low moves
west-northwestward at about 10 mph parallel to the coast of Mexico.
Moisture associated with this disturbance could produce heavy
rainfall and possible flash flooding across portions of Guatemala
and southeastern Mexico during the next couple of days.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...90 percent.

A low pressure system located more 900 miles southwest of the
southern tip of the Baja California peninsula is producing a large
area of cloudiness and thunderstorms. Environmental conditions are
expected to gradually improve, and a tropical depression could form
during the next few days while the system moves westward to
west-northwestward at about 10 mph.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...60 percent.

$$
Forecaster Stewart

WW 0598 Status Updates
STATUS REPORT ON WW 598 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 N EVV TO 20 E SLO TO 20 SE DEC. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1794 ..GLEASON..08/18/19 ATTN...WFO...LSX...ILX...PAH...IND... STATUS REPORT FOR WS 598 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC023-025-029-033-035-045-049-079-101-159-182340- IL . ILLINOIS COUNTIES INCLUDED ARE CLARK CLAY COLES CRAWFORD CUMBERLAND EDGAR EFFINGHAM JASPER LAWRENCE RICHLAND INC011-013-015-021-023-027-035-045-055-057-059-063-065-067-081- 083-095-097-105-107-109-119-121-133-135-139-145-153-157-159-165- 167-182340- IN . INDIANA COUNTIES INCLUDED ARE BOONE BROWN CARROLL CLAY CLINTON DAVIESS DELAWARE FOUNTAIN GREENE HAMILTON HANCOCK HENDRICKS HENRY HOWARD JOHNSON Read more

WW 0599 Status Updates
STATUS REPORT ON WW 599 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1796 ..GLEASON..08/18/19 ATTN...WFO...IWX...ILN...CLE... STATUS REPORT FOR WS 599 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS INC001-003-009-017-041-053-069-075-103-161-169-177-179-183- 182340- IN . INDIANA COUNTIES INCLUDED ARE ADAMS ALLEN BLACKFORD CASS FAYETTE GRANT HUNTINGTON JAY MIAMI UNION WABASH WAYNE WELLS WHITLEY OHC003-005-007-011-021-023-033-035-037-039-041-043-055-063-065- 069-075-077-083-085-091-093-095-099-101-103-107-109-113-117-123- 125-133-135-137-139-143-147-149-151-153-155-159-161-169-173-175- 182340- OH . OHIO COUNTIES INCLUDED ARE ALLEN ASHLAND ASHTABULA AUGLAIZE CHAMPAIGN CLARK CRAWFORD CUYAHOGA DARKE Read more

WW 599 SEVERE TSTM IN OH PA LE 181925Z - 190200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 599 NWS Storm Prediction Center Norman OK 325 PM EDT Sun Aug 18 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Parts of east central and northeast Indiana Western and northern Ohio Extreme northwest Pennsylvania Lake Erie * Effective this Sunday afternoon and evening from 325 PM until 1000 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Scattered thunderstorms are ongoing from northwest Ohio across Lake Erie along a remnant thunderstorm outflow boundary, and more storms will likely form through the afternoon farther south and west. The storm environment favors multicell clusters, and potentially marginal supercells, capable of producing damaging winds and isolated large hail through this evening. The severe thunderstorm watch area is approximately along and 45 statute miles north and south of a line from 10 miles north northwest of Muncie IN to 15 miles east northeast of Erie PA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 598... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 27025. ...Thompson Read more

WW 598 SEVERE TSTM IL IN MO 181805Z - 190000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 598 NWS Storm Prediction Center Norman OK 105 PM CDT Sun Aug 18 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern Illinois Central and southwest Indiana Southeast Missouri * Effective this Sunday afternoon and evening from 105 PM until 700 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Thunderstorms are expected to increase in coverage and intensity this afternoon from southeast Missouri into central Indiana, along a remnant outflow boundary. The storm environment across this corridor will favor multicell clusters capable of producing damaging winds and large hail through the afternoon. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 45 miles southwest of Farmington MO to 55 miles northeast of Indianapolis IN. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU8). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 27025. ...Thompson Read more

MD 1796 CONCERNING SEVERE THUNDERSTORM WATCH 599... FOR PORTIONS OF NORTHERN IN...SOUTHERN LOWER MI...AND NORTHERN OH
Mesoscale Discussion 1796 NWS Storm Prediction Center Norman OK 0542 PM CDT Sun Aug 18 2019 Areas affected...Portions of northern IN...southern Lower MI...and northern OH Concerning...Severe Thunderstorm Watch 599... Valid 182242Z - 190015Z The severe weather threat for Severe Thunderstorm Watch 599 continues. SUMMARY...An isolated severe threat will persist mainly across western and eastern portions of Severe Thunderstorm Watch 599 this evening. DISCUSSION...In the wake of storms earlier today, additional convection has recently developed along a cold front across southern Lower MI into northern IN. A shortwave trough will continue moving eastward across this region through the evening, with modestly enhanced mid-level southwesterly winds present. These storms will approach the western bounds of Severe Thunderstorm Watch 599 over the next couple of hours. Overall storm intensity remains somewhat unclear with prior convective overturning and the atmosphere attempting to destabilize early this evening. Regardless, there appears to be some potential for an isolated severe hail/wind threat across parts of northern IN, southern Lower MI, and northwestern OH early this evening as these storms continue eastward. A small westward extension in area for Severe Thunderstorm Watch 599 to include more of northern IN and northwestern OH could be warranted if storms strengthen substantially. Farther east, a small cluster persists over northeastern OH in a moderately unstable airmass. These storms should continue to pose an isolated severe threat as they move eastward into northwestern PA. ..Gleason.. 08/18/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CLE...ILN...DTX...IWX... LAT...LON 40788654 40988686 41678595 42058541 42048462 41678354 41368251 41508059 40958059 40958145 40618453 40788654 Read more

MD 1795 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF THE MID-ATLANTIC INTO THE NORTHEAST
Mesoscale Discussion 1795 NWS Storm Prediction Center Norman OK 0511 PM CDT Sun Aug 18 2019 Areas affected...portions of the Mid-Atlantic into the Northeast Concerning...Severe potential...Watch unlikely Valid 182211Z - 190015Z Probability of Watch Issuance...20 percent SUMMARY...Storms will continue to move east/northeast this evening across portions of the Mid-Atlantic into the Northeast. Isolated damaging wind gusts are the main threat, but storms will likely weaken around and after sunset. DISCUSSION...A hot, moist airmass across the Mid-Atlantic into the Northeast has resulted in moderate instability with MLCAPE of 1000-2000 J/kg this afternoon/evening. Additionally, an upper-level shortwave trough is moving over the eastern Great Lakes providing forcing for ascent aloft across the region. A mixed storm mode has resulted with weaker transient supercellular structures developing ahead of a QLCS stretching from central Upstate New York into eastern Pennsylvania. The main threat will be damaging winds given the potential of water-loaded downdrafts, steep low-level lapse rates, and the QLCS. Large hail will also be possible with storms on the southern end of the QLCS and with discrete cells developing in the warm sector ahead of it. Overall, isolated marginal severe wind and hail are expected during the next couple of hours with storm intensity likely diminishing around sunset. ..Nauslar/Guyer.. 08/18/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...OKX...ALY...PHI...BGM...BUF... CTP... LAT...LON 44307431 43767250 43007170 42137157 41457198 41087286 40527397 40077609 40527656 41167658 41837576 42217546 42867537 43417553 43997524 44247474 44307431 Read more

MD 1794 CONCERNING SEVERE THUNDERSTORM WATCH 598... FOR PORTIONS OF CENTRAL IN
Mesoscale Discussion 1794 NWS Storm Prediction Center Norman OK 0508 PM CDT Sun Aug 18 2019 Areas affected...Portions of central IN Concerning...Severe Thunderstorm Watch 598... Valid 182208Z - 182345Z The severe weather threat for Severe Thunderstorm Watch 598 continues. SUMMARY...A swath of damaging severe winds, some potentially significant, appears increasingly likely as storms approach Indianapolis over the next 1-2 hours. DISCUSSION...A HP supercell over far west-central IN has recently evolved into a small cluster, and has developed a strong rear inflow jet aloft per KIND radar. The VWP from KIND shows a veering and strengthening wind profile through mid levels, with 40-45 kt of flow present in the 4-6 km layer. Lower to mid 70s dewpoints and strong diurnal heating are contributing to MLCAPE of 2000-2500 J/kg downstream on the ongoing cluster. This environment appears likely to support continued storm intensity as this cluster develops east-southeastward late this afternoon and into the early evening. A swath of damaging winds appears increasingly likely across parts of central IN associated with this convection. Some of these winds could potentially be significant, with gusts greater than 75 mph possible, given the strong instability and steep low-level lapse rates present across this area. On its current trajectory, this cluster will approach the Indianapolis metro area in the next 1-2 hours. ..Gleason.. 08/18/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IND... LAT...LON 40218747 40308700 40258643 40048581 39738564 39278582 39318630 39418708 39698748 40218747 Read more

WW 0598 Status Updates
STATUS REPORT ON WW 598 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 WSW POF TO 30 SSE FAM TO 30 ENE FAM TO 20 E SLO TO 20 SE DEC. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1793 ..ELLIOTT..08/18/19 ATTN...WFO...LSX...ILX...PAH...IND... STATUS REPORT FOR WS 598 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC023-025-029-033-035-045-047-049-055-065-077-079-081-101-145- 159-181-185-191-193-199-182140- IL . ILLINOIS COUNTIES INCLUDED ARE CLARK CLAY COLES CRAWFORD CUMBERLAND EDGAR EDWARDS EFFINGHAM FRANKLIN HAMILTON JACKSON JASPER JEFFERSON LAWRENCE PERRY RICHLAND UNION WABASH WAYNE WHITE WILLIAMSON INC011-013-015-021-023-027-035-045-055-057-059-063-065-067-081- 083-095-097-105-107-109-119-121-133-135-139-145-153-157-159-165- 167-182140- IN . INDIANA COUNTIES INCLUDED ARE BOONE BROWN CARROLL Read more

MD 1793 CONCERNING SEVERE THUNDERSTORM WATCH 598... FOR PORTIONS OF SOUTHERN ILLINOIS...CENTRAL AND SOUTHWEST INDIANA...AND SOUTHEAST MISSOURI
Mesoscale Discussion 1793 NWS Storm Prediction Center Norman OK 0329 PM CDT Sun Aug 18 2019 Areas affected...Portions of southern Illinois...central and southwest Indiana...and southeast Missouri Concerning...Severe Thunderstorm Watch 598... Valid 182029Z - 182200Z The severe weather threat for Severe Thunderstorm Watch 598 continues. SUMMARY...Threat for damaging wind gusts and isolated large hail remains across Severe Thunderstorm Watch 0598. DISCUSSION...Thus far, much of the thunderstorm activity within Severe Thunderstorm Watch 0598 has been confined to portions of southeastern Missouri and southern Illinois, with more isolated activity across portions of Indiana. Where storms have formed/persisted, there has been episodic storm strengthening, with a few reports of damaging wind gusts across southern Illinois over the past hour. Damaging wind gusts and isolated large hail remain possible with the strongest storms amidst an environment characterized by 25-35 knots of effective bulk shear and MLCAPE around 2000 - 2500 J/kg. Radar/observational trends suggest the most likely area for strong/severe storms will remain over southwestern portions of the watch area through its expiration, with an extension in area possible over portions of southern Indiana if the storms moving into the area from southern Illinois intensify. ..Elliott.. 08/18/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LMK...IWX...IND...PAH...ILX...LSX...SGF... LAT...LON 37579111 39708741 40218632 40448561 40288550 39288542 38508662 38198718 36709037 36509068 36519131 37579111 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Aug 18 2019 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE LOWER OHIO VALLEY NORTHEASTWARD INTO THE LOWER GREAT LAKES AND CENTRAL NY... ...SUMMARY... Isolated to widely scattered damaging winds are possible from the lower Ohio Valley northeast into the lower Great Lakes mainly this afternoon and early evening. ...Discussion... Changes made from the previous outlook are based almost solely on convective trends with several thunderstorm clusters moving across the lower OH Valley and Great Lakes. 1) Expanded the Slight Risk ahead of the northern portion of a squall line moving east along the NY/PA border and for discrete supercell activity in central NY. Damaging gusts and marginally severe hail are possible. 2) Modified the western bound of severe probabilities over the middle MS Valley northeastward into the southern Great Lakes to reflect where preferred thunderstorm development is occurring on residual outflow. ..Smith.. 08/18/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 18 2019/ ...Great Lakes to the Ozarks this afternoon... A northern stream shortwave trough will progress eastward from northern MN across the upper Great Lakes, as midlevel heights begin to rise over the southern Plains. In advance of the northern stream trough, multiple remnant MCVs now from MO to WI will move eastward to IL and Lower MI during the afternoon. Ongoing convection in Lower MI has weakened slowly the past couple of hours. Some strengthening is possible early this afternoon along the leading edge of the outflow into eastern Lower MI as the low levels destabilize with surface heating, though confidence is not particularly high. Larger buoyancy will reside farther south into IN/IL where boundary-layer dewpoints in the low 70s persist beneath the eastern extent of an elevated mixed layer. Convective inhibition will weaken as surface temperatures warm into the upper 80s to lower 90s this afternoon, and new thunderstorm development is expected along the remnant outflow boundaries from MO into IL/IN. Rather modest vertical shear with up to 40 kt midlevel flow will generally favor multicell clusters with damaging winds, though midlevel lapse rates will be sufficiently steep for some hail threat. Storm development is a little less certain from southern MO into eastern OK, given the ongoing midlevel convection and persistent clouds. There is some potential for development this afternoon in the differential heating zone near the southern influence of the MCV over MO. Some warm advection will persist into this evening a bit farther to the northwest, though storm evolution/intensity is still in question. ...NY/PA this afternoon... A weak midlevel trough will move east-northeastward from the lower Great Lakes across NY/PA this afternoon. A broken band of storms now forming in northwest PA is likely the precursor to a loose band of storms that will persist through the afternoon and spread into NY. Multicell clusters and/or low-end supercell structures will pose some threat for damaging gusts this afternoon. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Aug 18 2019 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE LOWER OHIO VALLEY NORTHEASTWARD INTO THE LOWER GREAT LAKES AND CENTRAL NY... ...SUMMARY... Isolated to widely scattered damaging winds are possible from the lower Ohio Valley northeast into the lower Great Lakes mainly this afternoon and early evening. ...Discussion... Changes made from the previous outlook are based almost solely on convective trends with several thunderstorm clusters moving across the lower OH Valley and Great Lakes. 1) Expanded the Slight Risk ahead of the northern portion of a squall line moving east along the NY/PA border and for discrete supercell activity in central NY. Damaging gusts and marginally severe hail are possible. 2) Modified the western bound of severe probabilities over the middle MS Valley northeastward into the southern Great Lakes to reflect where preferred thunderstorm development is occurring on residual outflow. ..Smith.. 08/18/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 18 2019/ ...Great Lakes to the Ozarks this afternoon... A northern stream shortwave trough will progress eastward from northern MN across the upper Great Lakes, as midlevel heights begin to rise over the southern Plains. In advance of the northern stream trough, multiple remnant MCVs now from MO to WI will move eastward to IL and Lower MI during the afternoon. Ongoing convection in Lower MI has weakened slowly the past couple of hours. Some strengthening is possible early this afternoon along the leading edge of the outflow into eastern Lower MI as the low levels destabilize with surface heating, though confidence is not particularly high. Larger buoyancy will reside farther south into IN/IL where boundary-layer dewpoints in the low 70s persist beneath the eastern extent of an elevated mixed layer. Convective inhibition will weaken as surface temperatures warm into the upper 80s to lower 90s this afternoon, and new thunderstorm development is expected along the remnant outflow boundaries from MO into IL/IN. Rather modest vertical shear with up to 40 kt midlevel flow will generally favor multicell clusters with damaging winds, though midlevel lapse rates will be sufficiently steep for some hail threat. Storm development is a little less certain from southern MO into eastern OK, given the ongoing midlevel convection and persistent clouds. There is some potential for development this afternoon in the differential heating zone near the southern influence of the MCV over MO. Some warm advection will persist into this evening a bit farther to the northwest, though storm evolution/intensity is still in question. ...NY/PA this afternoon... A weak midlevel trough will move east-northeastward from the lower Great Lakes across NY/PA this afternoon. A broken band of storms now forming in northwest PA is likely the precursor to a loose band of storms that will persist through the afternoon and spread into NY. Multicell clusters and/or low-end supercell structures will pose some threat for damaging gusts this afternoon. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Aug 18 2019 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE LOWER OHIO VALLEY NORTHEASTWARD INTO THE LOWER GREAT LAKES AND CENTRAL NY... ...SUMMARY... Isolated to widely scattered damaging winds are possible from the lower Ohio Valley northeast into the lower Great Lakes mainly this afternoon and early evening. ...Discussion... Changes made from the previous outlook are based almost solely on convective trends with several thunderstorm clusters moving across the lower OH Valley and Great Lakes. 1) Expanded the Slight Risk ahead of the northern portion of a squall line moving east along the NY/PA border and for discrete supercell activity in central NY. Damaging gusts and marginally severe hail are possible. 2) Modified the western bound of severe probabilities over the middle MS Valley northeastward into the southern Great Lakes to reflect where preferred thunderstorm development is occurring on residual outflow. ..Smith.. 08/18/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 18 2019/ ...Great Lakes to the Ozarks this afternoon... A northern stream shortwave trough will progress eastward from northern MN across the upper Great Lakes, as midlevel heights begin to rise over the southern Plains. In advance of the northern stream trough, multiple remnant MCVs now from MO to WI will move eastward to IL and Lower MI during the afternoon. Ongoing convection in Lower MI has weakened slowly the past couple of hours. Some strengthening is possible early this afternoon along the leading edge of the outflow into eastern Lower MI as the low levels destabilize with surface heating, though confidence is not particularly high. Larger buoyancy will reside farther south into IN/IL where boundary-layer dewpoints in the low 70s persist beneath the eastern extent of an elevated mixed layer. Convective inhibition will weaken as surface temperatures warm into the upper 80s to lower 90s this afternoon, and new thunderstorm development is expected along the remnant outflow boundaries from MO into IL/IN. Rather modest vertical shear with up to 40 kt midlevel flow will generally favor multicell clusters with damaging winds, though midlevel lapse rates will be sufficiently steep for some hail threat. Storm development is a little less certain from southern MO into eastern OK, given the ongoing midlevel convection and persistent clouds. There is some potential for development this afternoon in the differential heating zone near the southern influence of the MCV over MO. Some warm advection will persist into this evening a bit farther to the northwest, though storm evolution/intensity is still in question. ...NY/PA this afternoon... A weak midlevel trough will move east-northeastward from the lower Great Lakes across NY/PA this afternoon. A broken band of storms now forming in northwest PA is likely the precursor to a loose band of storms that will persist through the afternoon and spread into NY. Multicell clusters and/or low-end supercell structures will pose some threat for damaging gusts this afternoon. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Aug 18 2019 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE LOWER OHIO VALLEY NORTHEASTWARD INTO THE LOWER GREAT LAKES AND CENTRAL NY... ...SUMMARY... Isolated to widely scattered damaging winds are possible from the lower Ohio Valley northeast into the lower Great Lakes mainly this afternoon and early evening. ...Discussion... Changes made from the previous outlook are based almost solely on convective trends with several thunderstorm clusters moving across the lower OH Valley and Great Lakes. 1) Expanded the Slight Risk ahead of the northern portion of a squall line moving east along the NY/PA border and for discrete supercell activity in central NY. Damaging gusts and marginally severe hail are possible. 2) Modified the western bound of severe probabilities over the middle MS Valley northeastward into the southern Great Lakes to reflect where preferred thunderstorm development is occurring on residual outflow. ..Smith.. 08/18/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 18 2019/ ...Great Lakes to the Ozarks this afternoon... A northern stream shortwave trough will progress eastward from northern MN across the upper Great Lakes, as midlevel heights begin to rise over the southern Plains. In advance of the northern stream trough, multiple remnant MCVs now from MO to WI will move eastward to IL and Lower MI during the afternoon. Ongoing convection in Lower MI has weakened slowly the past couple of hours. Some strengthening is possible early this afternoon along the leading edge of the outflow into eastern Lower MI as the low levels destabilize with surface heating, though confidence is not particularly high. Larger buoyancy will reside farther south into IN/IL where boundary-layer dewpoints in the low 70s persist beneath the eastern extent of an elevated mixed layer. Convective inhibition will weaken as surface temperatures warm into the upper 80s to lower 90s this afternoon, and new thunderstorm development is expected along the remnant outflow boundaries from MO into IL/IN. Rather modest vertical shear with up to 40 kt midlevel flow will generally favor multicell clusters with damaging winds, though midlevel lapse rates will be sufficiently steep for some hail threat. Storm development is a little less certain from southern MO into eastern OK, given the ongoing midlevel convection and persistent clouds. There is some potential for development this afternoon in the differential heating zone near the southern influence of the MCV over MO. Some warm advection will persist into this evening a bit farther to the northwest, though storm evolution/intensity is still in question. ...NY/PA this afternoon... A weak midlevel trough will move east-northeastward from the lower Great Lakes across NY/PA this afternoon. A broken band of storms now forming in northwest PA is likely the precursor to a loose band of storms that will persist through the afternoon and spread into NY. Multicell clusters and/or low-end supercell structures will pose some threat for damaging gusts this afternoon. Read more

WW 0599 Status Updates
STATUS FOR WATCH 0599 HAS NOT BEEN ISSUED YET Read more

WW 0599 Status Updates
STATUS FOR WATCH 0599 HAS NOT BEEN ISSUED YET Read more

WW 0598 Status Updates
STATUS REPORT ON WW 598 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..ELLIOTT..08/18/19 ATTN...WFO...LSX...ILX...PAH...IND... STATUS REPORT FOR WS 598 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC005-023-025-027-029-033-035-045-047-049-051-055-065-077-079- 081-101-121-133-145-157-159-163-181-185-189-191-193-199- 182040- IL . ILLINOIS COUNTIES INCLUDED ARE BOND CLARK CLAY CLINTON COLES CRAWFORD CUMBERLAND EDGAR EDWARDS EFFINGHAM FAYETTE FRANKLIN HAMILTON JACKSON JASPER JEFFERSON LAWRENCE MARION MONROE PERRY RANDOLPH RICHLAND ST. CLAIR UNION WABASH WASHINGTON WAYNE WHITE WILLIAMSON INC011-013-015-021-023-027-035-045-055-057-059-063-065-067-081- 083-095-097-105-107-109-119-121-133-135-139-145-153-157-159-165- 167-182040- IN . INDIANA COUNTIES INCLUDED ARE Read more

MD 1792 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF NORTHEAST IN INTO NORTHERN OH
Mesoscale Discussion 1792 NWS Storm Prediction Center Norman OK 0202 PM CDT Sun Aug 18 2019 Areas affected...portions of northeast IN into northern OH Concerning...Severe potential...Watch possible Valid 181902Z - 182100Z Probability of Watch Issuance...40 percent SUMMARY...Strong storms could produce damaging winds across parts of northeast IN into northern OH this afternoon and evening. DISCUSSION...Thunderstorms are quickly developing along an outflow boundary left by morning MCS. Strong differential heating along the boundary and a very moist boundary layer (dewpoints low to mid 70s) has resulted in moderate instability downstream. Steep low level lapse rates and a plume of moderately steep midlevel lapse rates overlie this region, which could support damaging winds given the marginally sheared environment. An additional severe thunderstorm watch may be needed across parts of northeast IN into northern OH soon. Further north into parts of southern Lower MI, continued/redeveloping severe threat is a bit more uncertain given convection that moved across the area during the morning and early afternoon hours. However, weak instability and dewpoints in the upper 60s still remain across this area, along with stronger effective shear. Hi-res guidance suggests storms could redevelop later this afternoon or evening as the airmass recovers and the main upper shortwave trough ejects over the area. Whether the boundary layer can recover and support a renewed severe threat remains uncertain and this may need to be addressed separately later this afternoon/evening. ..Leitman/Thompson.. 08/18/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND... LAT...LON 41618119 42118100 42688159 42868267 42658406 41128606 40378622 39928581 39828521 40098427 40968266 41618119 Read more