Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Nov 06 2022 12:46:54 ACUS01 KWNS 061246 SWODY1 SPC AC 061245 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 AM CST Sun Nov 06 2022 Valid 061300Z - 071200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Thunderstorms are possible over parts of the Northeast, Southeast, Texas to Mid-South overnight, and across the Pacific Northwest. ....Synopsis... In mid/upper levels, broadly cyclonic flow will persist across much of the western and northern CONUS through the period, reinforced by a series of strong northern-stream synoptic- to subsynoptic-scale perturbations. The leading of these features is a rapidly weakening/ejecting shortwave trough -- apparent in moisture-channel imagery with an embedded small circulation over the James Bay region. This trough will move over far northern QC today while weakening further. Upstream, a 500-mb cyclone now centered over southwestern MB, and its trough extending southward about 400-500 nm from there -- should move eastward across the Upper Great Lakes and northern ON through the period. The cyclone may weaken this evening then redevelop late tonight upon merging with a field of vorticity left by the leading perturbation over northern QC. Meanwhile, a deep, cold mid/upper cyclone (with widespread 500-mb temperatures in the -30s C) -- now centered west of Vancouver Island - will expand and move slowly southeastward. By the end of the period, the result should be a deep trough just off the Pacific Coast, with cyclonic flow over the West Coast States, and inland as far as the northern Rockies and Great Basin. Cooling midlevel temperatures with time will overlap the moist marine layer advecting inland across parts of western WA/OR and northwestern CA, contributing to the potential for sporadic, isolated thunderstorms near the coast. At the surface, 11Z analysis showed a slow-moving cold front from central QC across northwestern NY, eastern OH and eastern KY, becoming wavy and quasistationary across northwestern GA, southwestern AL and south-central LA. A second cold front -- related to the MB cyclone aloft -- extends across parts of MN, IA, northeastern KS, the southern TX Panhandle and central NM. The leading front is forecast to move eastward across the Mid-Atlantic region and New England through the period, reaching central/northern ME, coastal southern New England, and northern VA by 12Z tomorrow. The northern part of this boundary may be overtaken by the second cold front over the Northeast late tonight. ....Northeast... Widely scattered convection is possible this afternoon and evening over parts of PA, eastern NY and western New England -- mainly showers, with tops too low for much lightning generation, though isolated thunder cannot be ruled out. Activity should develop along/ahead of the front in a zone of neutral large-scale support, weak low-level lift and modest low/middle-level lapse rates, but also weak MLCINH and near 60 F surface dewpoints. Forecast midlevel lapse rates suggest relatively stable lapse rates above 500 mb, with the area being well-displaced from cooling aloft associated with either mid/upper trough. However, around 100-300 J/kg MLCAPE still may develop and extend into fast midlevel flow as warm and moist advection occur in the lower parts of profiles sampled by the initially unfavorable 12Z IAD/ALB soundings, suggesting a few strong gusts may be transferred to the surface in downdrafts. Flow aloft will veer slightly through the period as the leading shortwave trough departs away from the area, and the MB perturbation moves eastward; however, shear vectors should remain strong and generally boundary-parallel. Little net height change nor vorticity advection is expected, with both mid/ upper perturbations remaining distant. At this time, organized severe (50+ kt convective gust) potential appears too low and conditional to introduce a categorical area. ...Edwards/Smith.. 11/06/2022 $$ = = = 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) .