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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Thursday, August 4, 2022

SPC Aug 4, 2022 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0736 AM CDT Thu Aug 04 2022 Valid 041300Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FROM THE OH VALLEY INTO PARTS OF THE NORTHEAST...SOUTHERN OK TO THE TX PANHANDLE...CENTRAL MT...AND IN WESTERN NE... ...SUMMARY... Isolated damaging winds are possible this afternoon from the Ohio Valley into parts of the Northeast, Oklahoma into the Texas Panhandle, central Montana, and western Nebraska. ...Central MT this afternoon/evening... A midlevel shortwave trough over southern BC and WA will progress generally eastward to southern AB/SK/northern MT. A surface cyclone will precede the midlevel trough across southern AB/SK, and a trailing cold front will move southeastward across MT late this afternoon into tonight. Low-level moisture will be limited in advance of the front across MT, but deep mixing with strong surface heating will likely be sufficient for weak surface-based buoyancy with inverted-v profiles. Some increase in midlevel flow by afternoon, coupled with the weak buoyancy and DCAPE of 1200-1500 J/kg, will support isolated strong-severe outflow gusts with high-based convection in the zone of weak ascent along and just ahead of the front for a few hours this afternoon/evening. ...OH Valley into NY/VT this afternoon... In association with persistent overnight convection, an MCV will likely emerge in the vicinity of the MO Bootheel. Outflow with this convection will continue to move southward across AR today while weakening, and the cold pool is less defined farther east toward the lower OH Valley. The persistence of weak outflow and/or differential heating from the lower OH Valley into NY/VT, where MLCAPE will likely reach or exceed 2000 J/kg in an environment of weak vertical shear, will help loosely focus thunderstorm development (along with the Blue Ridge) and the potential for isolated strong/damaging downbursts this afternoon. ...Southern TX Panhandle into OK late this afternoon/evening... Proximal to the midlevel high over the Southern High Plains, another hot day with deep mixing is expected from the southeast TX Panhandle into central/southern OK. This corridor will lie along and just south of an outflow-reinforced front that will sag southward across OK through this evening. Weak lift along the wind shift, in combination with both MLCAPE/DCAPE of 1000-1500 J/kg and minimal convective inhibition, will support the threat for isolated thunderstorms with strong-severe downbursts for a few hours late this afternoon/evening. ...Western NE and vicinity this afternoon/evening... Strong surface heating and deep mixing will occur along a surface lee trough across western NE and vicinity, as a warm front develops northward through the day from NE toward SD. Though moisture will be somewhat marginal, MLCAPE could exceed 1000 J/kg with minimal convective inhibition, and a couple of storms may form along the surface trough. Inverted-v profiles and sufficiently long hodographs with effective bulk shear of 30-35 kt could support high-based supercells with a low-end threat for wind/hail. ..Thompson/Kerr.. 08/04/2022 Read more CHECK UPDATE ZOOM GRAPHIC