Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Oct 10 2023 12:52:20 ACUS01 KWNS 101252 SWODY1 SPC AC 101250 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Tue Oct 10 2023 Valid 101300Z - 111200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Severe thunderstorms are not expected through tonight. ....Synopsis outside Northwest... A large, deep-layer cyclone -- which is occluded in low levels -- continues to cover much of the east-central/northeastern CONUS, Great Lakes region, and eastern Canada. The center should continue to meander around northeastern ON/western QC south of James Bay through the period, while continuing to fill slowly throughout its depth. The associated surface frontal zone is well offshore from the entire Atlantic Coast except for having stalled near south FL and the Keys. There, isolated thunderstorms may occur amid modest deep-layer lapse rates and frontal lift, but also, rich moisture and weak MLCINH. To the west, a frontal-wave low over the northwestern Gulf, and associated warm/moist advection in low levels, may support isolated thunder from the TX coastal bend to the lower Rio Grande Valley. Ongoing eastern Pacific Hurricane Lidia and its eventual inland remains in low levels will stay well southwest of this area through the period, based on NHC forecasts. Its separating remnants aloft may influence low-level frontal-wave cyclogenesis over the northwestern Gulf near the end of this period and especially day 2, but any even indirectly associated/overland severe potential is expected to wait until after this period. Well upstream on the Rio Grande -- over the Big Bend/far west TX region and northward over the southern High Plains -- isolated, weak, high-based thunderstorms may develop this afternoon amid favorable heating and marginal moisture. ....Northwest... A substantial cyclone -- not as vast/intense as the one in eastern North America but still formidable in satellite appearance -- was evident in moisture-channel imagery over the northeastern Pacific, centered along 50N about 375 nm west of Vancouver Island. Its 500-mb center is expected to move eastward to east-southeastward through the period, reaching the Northwest Coast near UIL around 12Z tomorrow. A progression of basal shortwave perturbations and related height falls will impart a net negative tilt to the accompanying synoptic trough, which should extend southeastward from the low to northern NV by that time. Two primary, associated frontal bands of precip, with isolated embedded thunderstorms, should move ashore: the first ongoing, with shallower/weaker buoyancy, and a second, broader convective area from midafternoon into early evening local time. Time series of forecast soundings through the passage of the second area suggest hodograph size decreasing as cooling aloft increases and deepens the buoyant layer; however, a brief overlap window may develop where storm-scale rotation can be sustained in at least marginally favorable low-level shear environment. At this time, near-coastal tornado probabilities are not zero, but appear too conditional and uncertain for a categorical outlook. Farther inland over the northern Rockies and vicinity, shots of large-scale ascent preceding the main synoptic trough -- and associated with several preceding vorticity lobes -- will maintain favorable instability aloft. Overlap of that with weak but sufficient low/middle-level moisture, in tandem with a diurnally heated boundary layer, will support isolated thunderstorm potential late this afternoon into early evening. ...Edwards/Broyles.. 10/10/2023 $$ = = = 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) .