Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 31 2023 17:32:17 ACUS02 KWNS 311732 SWODY2 SPC AC 311730 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Mon Jul 31 2023 Valid 011200Z - 021200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH DAKOTA AND NORTHWESTERN MINNESOTA... ....SUMMARY... Severe thunderstorms capable of producing large hail and damaging winds appear possible Tuesday across parts of North Dakota into northern Minnesota, and the central High Plains into the mid Missouri Valley. Thunderstorms capable of producing occasional damaging winds may also occur over parts of the coastal Southeast. ....Synopsis... An expansive upper ridge will remain anchored over the central CONUS on Tuesday. Multiple weak mid-level disturbances are forecast to rotate around the apex of the upper ridge across the northern/central Plains and Upper Midwest. Upper troughing is expected to persist across the eastern states. Between these features, a belt of modestly enhanced mid-level west-northwesterly flow will extend from the northern Plains and Upper Midwest to parts of the Southeast. ....Northern Plains/Upper Midwest... A weak mid-level shortwave trough should dampen the northern extent of upper ridging over central Canada and the northern Plains on Tuesday. At the surface, a cold front is forecast to move east-southeastward across these areas through the period. Rich low-level moisture, characterized by mid 60s to perhaps low 70s surface dewpoints, should be in place ahead of the front across ND into northern MN. Thunderstorms should develop along/ahead of the front by Tuesday afternoon in a moderately to strongly unstable airmass. The presence of steep mid-level lapse rates and around 30-40 kt of effective bulk shear should aid in some threat for supercells capable of producing large hail. Otherwise, one or more clusters may eventually develop along the length of the cold front and pose more of a severe wind threat as convection develops south-southeastward through Tuesday evening. Given a greater signal for supercells and multicells across this area, have introduced a Slight Risk. This activity should eventually weaken with eastward and southward extent into the northern Plains and Upper Midwest as it encounters a less unstable airmass. ....Central High Plains into the Mid Missouri Valley... Scattered to numerous thunderstorms should once again develop over the higher terrain of the central Rockies early Tuesday afternoon, and eventually spread eastward into the adjacent central High Plains through Tuesday evening. One or more weak mid-level vorticity maxima may aid in this convective development. While deep-layer shear appears fairly modest, generally 30 kt or less, convection should gradually strengthen as it encounters a more unstable airmass across eastern CO and vicinity. Most high-resolution guidance suggests that a small cluster will eventually consolidate and spread eastward across the central Plains Tuesday evening and possible continuing overnight. Isolated hail may occur with the initially more cellular convection, while severe/damaging winds appear more of a concern with eastward extent if a cluster does develop. Have therefore expanded the Marginal Risk eastward to account for this possibility. Farther east into the mid MO Valley, thunderstorms may be ongoing at the beginning of the period in a low-level warm advection regime. While most of this activity will probably remain sub-severe, some threat for hail and gusty winds may exist with the more robust cores through Tuesday morning. The potential for additional convective development Tuesday afternoon appears highly uncertain given weak large-scale forcing. But, there appears to be a signal for renewed thunderstorms in another low-level warm advection regime Tuesday night through early Wednesday morning. With ample MUCAPE and strong deep-layer shear forecast, any elevated supercells which can develop may pose an isolated threat for large hail and strong/gusty winds. ....Coastal Southeast... Isolated to scattered thunderstorms should develop Tuesday afternoon along and east of a weak lee surface trough, with additional convective development possible along the Atlantic sea breeze. Weak to locally moderate instability should develop with daytime heating of a moist low-level airmass. But, poor mid-level lapse rates will probably tend to limit updraft intensity to some extent. Still, around 20-30 kt of deep-layer shear should prove adequate for modest convective organization. An isolated threat for damaging winds may exist with the stronger clusters that form and spread eastward through Tuesday evening, before they eventually weaken and/or move offshore. ...Gleason.. 07/31/2023 $$ = = = 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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .