Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 06 2024 05:32:36 ACUS01 KWNS 060532 SWODY1 SPC AC 060531 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1231 AM CDT Tue Aug 06 2024 Valid 061200Z - 071200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDWEST TO THE MID-ATLANTIC...OVER MONTANA INTO WESTERN SOUTH DAKOTA...AND PARTS OF CENTRAL/SOUTHERN ARIZONA... ....SUMMARY... Scattered strong storms are likely over much of Montana into western South Dakota, as well as from parts of Ohio into New Jersey, and across parts of Arizona. ....MI/IN/OH into the Northern Mid-Atlantic Vicinity... A convectively enhanced shortwave impulse will track east from southern Lake Michigan to southern New England today into this evening. Enhanced midlevel flow associated with this feature will overspread the region. At the surface, a stalled boundary will extend west to east from northern IN/OH into central PA and eventually offshore in the vicinity of Long Island. An MCV is forecast to shift east along this boundary today into this evening. A very moist airmass is in place, and surface dewpoints in the low to possibly mid-70s F are expected to contribute to moderate to strong instability. Forecast soundings depict steepening low-level lapse rates and PW values near 2 inches. Furthermore, supercell wind profiles are evident. Low-level hodographs will be somewhat enlarged and favorably curved in the vicinity of the surface boundary and near the eastward-developing MCV. This will support a risk for a few tornadoes from northern OH into western PA. Otherwise, cells/clusters will pose a risk for damaging gusts and marginal hail across a broader area within the theta-e gradient/surface boundary from IN to the northern Mid-Atlantic coast. With time, and aided enhanced ascent from the MCV, one or more bowing segments may develop. If this occurs, damaging-wind potential could increase across portions of the area. ....Northern Rockies to the Northern High Plains... An upper shortwave trough will develop south over western Canada and the northern Rockies. This will flatten the upper ridge oriented over the MT and the Dakotas and result in increasing mid/upper westerly flow across the region. Cooling aloft will foster steep midlevel lapse rates, while increasing midlevel moisture further aids in weak to moderate destabilization over the region (MLCAPE 500-1500 J/kg). Initial convection is forecast to develop over the higher terrain of western MT by early/mid afternoon. Around 25-35 kt effective shear magnitudes will support organized cells. Meanwhile, cooling midlevel temperatures and elongated/straight hodographs should support isolated large hail with initial discrete storms. With time, clustering and outflow consolidation is expected as convection shifts east into central/eastern MT and eventually the western Dakotas during the evening. Steep low-level lapse rates and deeply mixed boundary layer will support strong to severe outflow gusts with this activity. ....Central/Southern AZ... Midlevel easterly flow will increase to around 20-25 kt as a weak impulse migrates westward near the AZ/Mexican border. Steep low to midlevel lapse rates and nearly 1.5 inch PW values will support MLCAPE around 1500-2000 J/kg amid 30 kt effective shear magnitudes. Initial thunderstorm development is expected over higher terrain by early to mid-afternoon. With time, clustering and outflow consolidation should result in westward propagating convection posing a risk for severe gusts into the evening. ....Coastal Carolinas... Tropical Storm Debby will not move much today, remaining near coastal SC. Overall tornado potential appears somewhat less compared to the previous couple of days, as widespread heavy rain will limit low-level destabilization. However, enhanced low-level shear within the eastern semicircle may support a low risk for a tornado or two across portions of coastal SC and southeast NC. ....Central High Plains... A post-frontal upslope flow regime will maintain modest boundary-layer moisture across the central High Plains vicinity. Strong heating and steep midlevel lapse rates will support MLCAPE to around 1500 J/kg. While deep-layer flow will remain modest, vertically veering wind profiles will provide sufficient shear for semi-organized cells. Convection will develop near higher terrain by 18-20z and spread east into the adjacent plains through the evening. This activity will pose a risk for marginal wind/hail before weakening after sunset. ...Leitman/Thornton.. 08/06/2024 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .