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  1. MD 1485 CONCERNING SEVERE THUNDERSTORM WATCH 510... FOR PORTIONS OF SOUTHERN SOUTH DAKOTA INTO NORTHERN NEBRASKA Mesoscale Discussion 1485 NWS Storm Prediction Center Norman OK 1014 PM CDT Mon Jul 15 2019 Areas affected...Portions of southern South Dakota into northern Nebraska Concerning...Severe Thunderstorm Watch 510... Valid 160314Z - 160445Z The severe weather threat for Severe Thunderstorm Watch 510 continues. SUMMARY...Severe threat continues for the remainder of Severe Thunderstorm Watch 0510. Severe wind gusts will be the main threat, with occasional large hail possible. Trends are currently being monitored for the potential of a downstream WW issuance. DISCUSSION...Multicellular convection has gradually congealed into a loosely organized MCS along the northwest NE/southwest SD border, with a few severe wind reports noted within the past couple of hours. While the overall kinematic fields are weak downstream of the MCS (with no anticipated appreciable ramp up in a nocturnal low-level jet), adequate buoyancy resides across all along the NE/SD border, owing to steep lapse rates in the 700-300 mb layer, and rich low-level moisture extending up to 850 mb (per latest RAP forecast soundings). As such, ample elevated instability is expected throughout the night in advance of the storms, even with a gradually stabilizing boundary layer, which may sustain the MCS, as indicated by several members of the 00Z HREF, and the last few runs of the HRRR. Still, the marginal deep-layer and low-level shear environment may also promote progressive cold pools, which may outrun the antecedent convection, potentially weakening the MCS. Given the uncertainty in MCS evolution within the ambient weakly forced but highly buoyant environment, convective trends will continue to be monitored for a potential downstream WW issuance. ..Squitieri/Grams.. 07/16/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FSD...OAX...GID...LBF...UNR...CYS... LAT...LON 41050128 42020215 42600255 43130287 43360279 43450236 43349979 43129784 42199766 41849784 41509829 41269881 41050128 Read more View the full article
  2. No Mesoscale Discussions are in effect as of Tue Jul 16 01:46:02 UTC 2019. View the full article
  3. MD 1484 CONCERNING SEVERE THUNDERSTORM WATCH 509... FOR PORTIONS OF SOUTHEASTERN MN INTO WESTERN/CENTRAL WI Mesoscale Discussion 1484 NWS Storm Prediction Center Norman OK 0715 PM CDT Mon Jul 15 2019 Areas affected...Portions of southeastern MN into western/central WI Concerning...Severe Thunderstorm Watch 509... Valid 160015Z - 160145Z The severe weather threat for Severe Thunderstorm Watch 509 continues. SUMMARY...Primarily an isolated strong to damaging wind threat continues across remaining valid portions of Severe Thunderstorm Watch 509. Downstream watch issuance into more of western/central WI and southeastern MN is not expected this evening. DISCUSSION...Over the past couple of hours convection has consolidated into a line along a pre-frontal surface trough extending from northwestern WI into parts of southeastern MN. Given the linear mode, isolated strong to damaging outflow winds should be the main threat through the remainder of the evening. However, a brief tornado cannot be ruled out in the short term along the southern flank of the line, where a recent rotational velocity couplet around 40 kt was observed in Scott County MN before weakening. Instability rapidly decreases into central WI and far southeastern MN, where convective overturning from earlier thunderstorms has generally stabilized the low levels. Current expectations are for the ongoing line of storms to weaken as it progresses southeastward into WI and far southeastern MN through the evening. Therefore, an additional Severe Thunderstorm Watch into more of western/central WI and far southeastern MN is not anticipated at this time. ..Gleason.. 07/16/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GRB...DLH...ARX...MPX... LAT...LON 44159474 44869453 45159419 45099287 45939181 46459113 46559057 46469030 46309012 46238981 45878930 44318998 43549129 43549417 44159474 Read more View the full article
  4. MD 1482 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF WESTERN UPPER MI INTO FAR NORTH-CENTRAL WI Mesoscale Discussion 1482 NWS Storm Prediction Center Norman OK 0610 PM CDT Mon Jul 15 2019 Areas affected...Portions of western Upper MI into far north-central WI Concerning...Severe potential...Watch unlikely Valid 152310Z - 160045Z Probability of Watch Issuance...20 percent SUMMARY...An isolated strong/gusty wind threat may exist across parts of western Upper MI into far north-central WI this evening. Watch issuance appears unlikely. DISCUSSION...A line of convection that has developed ahead of a surface cold front in association with a low-amplitude shortwave trough over MN and southern Ontario will continue eastward across western Lake Superior. With generally 1000-1500 J/kg of MLCAPE (locally stronger) and 25-40 kt of mid-level westerly flow present over this region, there is some concern that the line will be able to maintain its intensity as it crosses Lake Superior and subsequently moves over parts of western Upper MI and far north-central WI over the next couple of hours. The best threat area does appear to be spatially confined to a small part of western Upper MI in the wake of earlier convection now over northeastern WI and northward-moving outflow. Still, mainly an isolated strong/gusty wind threat could exist through the evening where diurnal heating has been able to steepen low-level lapse rates. Although watch issuance appears unlikely at this time, observational trends will continue to be monitored. ..Gleason/Grams.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MQT...GRB... LAT...LON 46518725 46088758 45888815 45888928 46318991 46649029 46838993 47418847 47568786 47488755 47088743 46518725 Read more View the full article
  5. MD 1483 CONCERNING SEVERE THUNDERSTORM WATCH 510... FOR EASTERN WYOMING INTO SOUTHWESTERN SOUTH DAKOTA AND WESTERN INTO CENTRAL NEBRASKA Mesoscale Discussion 1483 NWS Storm Prediction Center Norman OK 0642 PM CDT Mon Jul 15 2019 Areas affected...Eastern Wyoming into southwestern South Dakota and western into central Nebraska Concerning...Severe Thunderstorm Watch 510... Valid 152342Z - 160115Z The severe weather threat for Severe Thunderstorm Watch 510 continues. SUMMARY...The severe threat continues across Severe Thunderstorm Watch 0510. Large hail and severe wind gusts remain the primary threat. Upscale growth of convection remains possible across northwestern portions of the watch, where severe winds may become the predominant threat. Outflow from earlier storms have stabilized the airmass across southeast parts of the watch, where the short term severe threat has been tempered. DISCUSSION...Semi-discrete to discrete storms, including transient supercell structures, have developed and matured across the lower-terrain areas in eastern Wyoming over the past few hours. Ample buoyancy (1500-2500 J/kg MLCAPE) and adequate deep-layer shear (35-45 knots of bulk effective shear) are in place to foster the maintenance of this convection. Poor speed and directional shear in the lowest 3 km, however, suggests that some outflow dominant tendencies should exist with some of the more intense cells with more robust, water/hail loaded downdrafts. As such, cold-pool merging is expected to commence over the next few hours, promoting upscale growth for potential MCS development, as suggested by both the 12Z HREF and the last few runs of the HRRR. Should this occur, severe wind gusts should become the main threat, particularly in far east WY into southwest SD. The intensity of the potential MCS is somewhat uncertain, as a meager to negligible low-level jet is expected to develop during the evening. As such, robustness of the MCS will depend entirely on cold pool propagation processes, and the amount of buoyancy available ahead of the convective leading line. Meanwhile, multicellular convection in northern Nebraska, supported by 3000+ J/kg MLCAPE, have exhibited copious outflow given the very weak low-level and deep-layer shear environment in place. A substantial cold pool has been left behind across southeast parts of Severe Thunderstorm Watch 0510, suggesting that the severe threat has been dampened to a degree via boundary layer stratification and mid-level convective overturning/diminishing of lapse rates. Still, at least a few hours of diurnal heating remain, and the chances for additional severe weather will hinge on the trajectory and intensity of the potential aforementioned MCS. ..Squitieri/Grams.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...LBF...UNR...CYS...BYZ...RIW... LAT...LON 41280519 44830716 44820124 41289960 41280519 Read more View the full article
  6. MD 1483 CONCERNING SEVERE THUNDERSTORM WATCH 510... FOR EASTERN WYOMING INTO SOUTHWESTERN SOUTH DAKOTA AND WESTERN INTO CENTRAL NEBRASKA Mesoscale Discussion 1483 NWS Storm Prediction Center Norman OK 0642 PM CDT Mon Jul 15 2019 Areas affected...Eastern Wyoming into southwestern South Dakota and western into central Nebraska Concerning...Severe Thunderstorm Watch 510... Valid 152342Z - 160115Z The severe weather threat for Severe Thunderstorm Watch 510 continues. SUMMARY...The severe threat continues across Severe Thunderstorm Watch 0510. Large hail and severe wind gusts remain the primary threat. Upscale growth of convection remains possible across northwestern portions of the watch, where severe winds may become the predominant threat. Outflow from earlier storms have stabilized the airmass across southeast parts of the watch, where the short term severe threat has been tempered. DISCUSSION...Semi-discrete to discrete storms, including transient supercell structures, have developed and matured across the lower-terrain areas in eastern Wyoming over the past few hours. Ample buoyancy (1500-2500 J/kg MLCAPE) and adequate deep-layer shear (35-45 knots of bulk effective shear) are in place to foster the maintenance of this convection. Poor speed and directional shear in the lowest 3 km, however, suggests that some outflow dominant tendencies should exist with some of the more intense cells with more robust, water/hail loaded downdrafts. As such, cold-pool merging is expected to commence over the next few hours, promoting upscale growth for potential MCS development, as suggested by both the 12Z HREF and the last few runs of the HRRR. Should this occur, severe wind gusts should become the main threat, particularly in far east WY into southwest SD. The intensity of the potential MCS is somewhat uncertain, as a meager to negligible low-level jet is expected to develop during the evening. As such, robustness of the MCS will depend entirely on cold pool propagation processes, and the amount of buoyancy available ahead of the convective leading line. Meanwhile, multicellular convection in northern Nebraska, supported by 3000+ J/kg MLCAPE, have exhibited copious outflow given the very weak low-level and deep-layer shear environment in place. A substantial cold pool has been left behind across southeast parts of Severe Thunderstorm Watch 0510, suggesting that the severe threat has been dampened to a degree via boundary layer stratification and mid-level convective overturning/diminishing of lapse rates. Still, at least a few hours of diurnal heating remain, and the chances for additional severe weather will hinge on the trajectory and intensity of the potential aforementioned MCS. ..Squitieri/Grams.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...LBF...UNR...CYS...BYZ...RIW... LAT...LON 41280519 44830716 44820124 41289960 41280519 Read more View the full article
  7. MD 1482 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF WESTERN UPPER MI INTO FAR NORTH-CENTRAL WI Mesoscale Discussion 1482 NWS Storm Prediction Center Norman OK 0610 PM CDT Mon Jul 15 2019 Areas affected...Portions of western Upper MI into far north-central WI Concerning...Severe potential...Watch unlikely Valid 152310Z - 160045Z Probability of Watch Issuance...20 percent SUMMARY...An isolated strong/gusty wind threat may exist across parts of western Upper MI into far north-central WI this evening. Watch issuance appears unlikely. DISCUSSION...A line of convection that has developed ahead of a surface cold front in association with a low-amplitude shortwave trough over MN and southern Ontario will continue eastward across western Lake Superior. With generally 1000-1500 J/kg of MLCAPE (locally stronger) and 25-40 kt of mid-level westerly flow present over this region, there is some concern that the line will be able to maintain its intensity as it crosses Lake Superior and subsequently moves over parts of western Upper MI and far north-central WI over the next couple of hours. The best threat area does appear to be spatially confined to a small part of western Upper MI in the wake of earlier convection now over northeastern WI and northward-moving outflow. Still, mainly an isolated strong/gusty wind threat could exist through the evening where diurnal heating has been able to steepen low-level lapse rates. Although watch issuance appears unlikely at this time, observational trends will continue to be monitored. ..Gleason/Grams.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MQT...GRB... LAT...LON 46518725 46088758 45888815 45888928 46318991 46649029 46838993 47418847 47568786 47488755 47088743 46518725 Read more View the full article
  8. Special Weather Statement issued July 15 at 6:37PM EDT by NWS View the full article
  9. Special Weather Statement issued July 15 at 6:15PM EDT by NWS View the full article
  10. MD 1481 CONCERNING SEVERE THUNDERSTORM WATCH 509... FOR PORTIONS OF MN AND WESTERN WI Mesoscale Discussion 1481 NWS Storm Prediction Center Norman OK 0458 PM CDT Mon Jul 15 2019 Areas affected...Portions of MN and western WI Concerning...Severe Thunderstorm Watch 509... Valid 152158Z - 152330Z The severe weather threat for Severe Thunderstorm Watch 509 continues. SUMMARY...Both damaging winds and large hail will remain possible with storms across Severe Thunderstorm Watch 509 this evening. DISCUSSION...A line of convection approaching western Lake Superior in the MN Arrowhead will remain capable of producing damaging winds in the short term. Farther south, a cluster of storms has developed ahead of a cold front just to the northwest of the Twin Cities. Although mid-level flow gradually weakens with southward extent across MN, around 25-30 kt of effective bulk shear will still promote multicells capable of producing both large hail and strong to locally damaging winds. Severe Thunderstorm Watch 509 has been expanded southward to include more of central/southern MN to account for this recent convective development. Additional storms may also form along the cold front through this evening, with mainly a damaging wind threat given a predominately linear mode expected. ..Gleason.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DLH...MPX...FGF... LAT...LON 46019563 46119409 47219281 48149051 48018960 46679049 45399096 44669099 44609208 44369314 44399449 45009606 45189605 46019563 Read more View the full article
  11. MD 1480 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR PORTIONS OF EASTERN WYOMING...SOUTHWEST SOUTH DAKOTA...WESTERN NEBRASKA Mesoscale Discussion 1480 NWS Storm Prediction Center Norman OK 0320 PM CDT Mon Jul 15 2019 Areas affected...portions of eastern Wyoming...southwest South Dakota...western Nebraska Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 152020Z - 152245Z Probability of Watch Issuance...80 percent SUMMARY...Storm coverage will increase this afternoon/evening across portions of the central/northern High Plains. Severe hail and wind are the main threats, and a severe thunderstorm watch issuance is likely. DISCUSSION...An upper-level disturbance is moving over western South Dakota and northwest Nebraska while another disturbance is moving over western Wyoming. These disturbances are helping to provide forcing for ascent and aiding convective initiation along with insolation, terrain, and surface boundaries. The best buoyancy is located across western Nebraska and south/east of the Black Hills in South Dakota where surface dewpoints are in the 50s to upper 60s F and temperatures in the 80s to low 90s F. Storms will move eastward off the higher terrain in Wyoming and onto the High Plains this afternoon/evening. Additional development is also possible along the cold front in South Dakota and along surface convergence ahead of this (possibly a pre-frontal trough). Supercells are possible, at least initially, given the 40-50 knots of effective bulk shear across the area, but upscale growth and a mixed storm mode are likely this evening with the upper-level forcing. Storms will likely intensify with time as they move into better instability. Large hail and damaging wind gusts are the main threats and a severe thunderstorm watch issuance is likely for a large portion of the MCD. ..Nauslar/Dial.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...CYS...BYZ...RIW... LAT...LON 41730110 41040225 41040328 41250421 41610519 42300602 42940648 43480655 45050560 45510536 45620464 45430389 44300234 43570164 43320087 42940012 42739983 42549975 42270001 42060043 41730110 Read more View the full article
  12. MD 1479 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHEAST SD INTO SOUTHWEST MN AND FAR NORTHWEST IA Mesoscale Discussion 1479 NWS Storm Prediction Center Norman OK 0312 PM CDT Mon Jul 15 2019 Areas affected...portions of southeast SD into southwest MN and far northwest IA Concerning...Severe potential...Watch unlikely Valid 152012Z - 152145Z Probability of Watch Issuance...20 percent SUMMARY...A couple of strong cells could produce locally strong wind gusts and possibly hail through this evening. Overall threat will remain isolated and a watch is not expected at this time. DISCUSSION...A CU field continues to develop in a strongly unstable environment just ahead of the surface cold front from south-central SD into southwest MN, with a few TCU noted in visible imagery. Forcing for ascent associated with the shortwave impulse moving into northern MN becomes weaker with southward extent, but isolated cells are possible in a mostly uncapped environment. Effective shear is weak, on the order of 20-30 kt, which may limit storm organization in the absence of stronger forcing. Nevertheless, MLCAPE greater than 2500 J/kg and midlevel lapse rates around 7-7.5 C/km could support briefly intense cells. Likewise, very weak low level winds and steep low level lapse rates could promote strong downburst winds in strongest cells. Overall, the threat is expected to remain isolated and it does not appear a watch is needed at this time. ..Leitman/Dial.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...DMX...FSD...OAX...ABR...LBF... LAT...LON 44029934 44509836 45359646 45479558 45279472 44889436 44409424 44059422 43569459 43149558 42909673 42839822 43069921 43599938 44029934 Read more View the full article
  13. MD 1478 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR SOUTHERN MONTANA AND NORTHERN WYOMING Mesoscale Discussion 1478 NWS Storm Prediction Center Norman OK 0236 PM CDT Mon Jul 15 2019 Areas affected...southern Montana and northern Wyoming Concerning...Severe potential...Watch possible Valid 151936Z - 152200Z Probability of Watch Issuance...40 percent SUMMARY...Storms will move off the higher terrain and spread eastward this afternoon and evening across southern Montana and northern Wyoming. Large hail and damaging winds may occur with these storms and a severe thunderstorm watch issuance is possible. DISCUSSION...Per satellite imagery and mesoanalysis it appears a couple of weak mid-level disturbances are moving over central Idaho/far western Montana and western Wyoming. Forcing for ascent associated with these disturbances and deep terrain-thermal circulations are helping to initiate storms over the higher terrain. Temperatures are warming into the upper 70 to mid 80s F, but surface moisture remains rather pedestrian west of the Big Horns (mostly 45-50 F). As a result, marginal buoyancy exists across the area, although some steeper mid-level lapse rates (7.5+ C/km) and stronger effective bulk shear (35-45 knots) should help compensate somewhat. A mixed storm mode is expected with isolated-scattered supercells before likely building upscale into loose cluster(s) this afternoon and evening. Severe hail may occur given the shear, mid-level lapse rates, and CAPE in the hail growth region while severe wind may also occur with relatively high LCLs. ..Nauslar/Dial.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...UNR...BYZ...RIW...TFX...PIH... LAT...LON 43090733 42940789 42870831 42920880 43260902 43730930 44260977 44591138 44801211 45341228 45701223 46171177 46471110 46551100 46540811 46110698 45280591 44570578 43840623 43650643 43340688 43090733 Read more View the full article
  14. MD 1477 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHEAST MN INTO CENTRAL WI Mesoscale Discussion 1477 NWS Storm Prediction Center Norman OK 0157 PM CDT Mon Jul 15 2019 Areas affected...southeast MN into central WI Concerning...Severe potential...Watch unlikely Valid 151857Z - 152030Z Probability of Watch Issuance...20 percent SUMMARY...Isolated strong storms could produce hail and locally strong wind gusts. DISCUSSION...Isolated thunderstorms are developing across west-central WI this afternoon in an area of strong instability downstream from an MCV currently over southeast MN. These storms may pose a marginal risk for hail approaching 1-inch in diameter and locally strong wind gusts. However, weak effective shear will limit overall organization of any storm clusters that develop. Additionally, an area of low to midlevel dry air has been noted on water vapor imagery to the north of the MCV and south of the southeastward-advancing cold front. This is further evident in visible satellite imagery, where little cloud cover is present from near AQP in southwest MN eastward to near RZN in western WI. This may be suppressing convective potential across central/southern MN and adjacent parts of WI in the short term, until stronger ascent arrives with the approach of the cold front and shortwave impulse. Hi-res guidance continues to struggle with ongoing convection, providing little confidence in overall evolution of potential severe threat across parts of southern MN into central WI through the afternoon. As such, trends will be monitored for possible watch issuance, but a watch does not appear necessary in the short-term. ..Leitman/Dial.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GRB...DLH...ARX...MPX... LAT...LON 45359223 45629147 45749032 45408976 45068959 44678968 44219074 43739229 43619304 43889343 44419334 45039277 45359223 Read more View the full article
  15. MD 1476 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF NORTHERN AND CENTRAL MN INTO NORTHWEST WI Mesoscale Discussion 1476 NWS Storm Prediction Center Norman OK 1203 PM CDT Mon Jul 15 2019 Areas affected...portions of northern and central MN into northwest WI Concerning...Severe potential...Watch likely Valid 151703Z - 151830Z Probability of Watch Issuance...80 percent SUMMARY...The severe threat will continue to increase across portions of northern/central MN into northern WI this afternoon. Damaging wind gusts and some hail will be possible and a watch will likely be needed in the next couple of hours. DISCUSSION...A band of storms continues to track east across north-central MN at midday. These storms are likely still somewhat elevated per mesoanalysis and surface temperatures still a couple of degrees cooler than needed for surface based convection per 12z INL RAOB. However, several locations further south toward central MN have warmed into the 84-86 degree temperature range and the CU field across the region is beginning to develop and become bettered defined with time. With continued heating, surface-based convection is expected to develop within the next few hours across parts of northern MN and eventually into northern WI. One or more bands of storms is possible this afternoon, with TCU continuing to develop ahead of the cold front to the south-southwest of current storms. Also noted in surface analysis is an area of surface confluence and low level moist axis ahead of the frontal band across north-central MN. Convection may eventually develop here as well as upper forcing for ascent increases with the approaching of the shortwave impulse. Hi-res guidance is doing a poor job so far in handing ongoing convection, with most HRRR/WRF guidance not depicting any storms ongoing across northern MN. This does lead to some uncertainty in how things will evolve/timing of greater severe threat heading into the afternoon. Regardless, a very moist boundary layer beneath steep midlevel lapse rates will support strong instability. Deep layer shear will increase some as the shortwave impulse shifts east/northeast, but in general will remain modest. Nevertheless, one or more bands of severe storms capable of damaging winds and possibly hail will spread eastward across northern MN into northern WI through the afternoon. A watch will likely be needed for portions of the MCD area in the next couple of hours. ..Leitman/Dial.. 07/15/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DLH...MPX...FGF...ABR... LAT...LON 48049084 47179089 46189111 45959113 45329164 44989232 44859322 45019401 45339528 45759640 46629672 47089658 48069578 48659472 48799400 48739341 48479200 48239108 48049084 Read more View the full article
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