Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Oct 27 2023 04:47:24 ACUS02 KWNS 270447 SWODY2 SPC AC 270445 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1145 PM CDT Thu Oct 26 2023 Valid 281200Z - 291200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... The risk for severe thunderstorms appears negligible across the U.S., Saturday through Saturday night. ....Discussion... Although a developing mid/upper high across the northeastern Pacific may become suppressed southeastward and begin to weaken, larger-scale ridging just offshore of the North American Pacific coast appears likely to remain amplified through this period. Downstream, the center of a broad, but weakening, mid-level low is forecast to shift northeastward into Baffin Bay, while a prominent mid-level ridge is maintained across much of the Gulf of Mexico and Southeast into adjacent western Atlantic. There is some spread among the various model output, but mid-level flow may trend broadly anticyclonic as far northwest and north of the subtropical ridge as the Upper Midwest into the Northeast, in the wake of one strengthening mid-level short wave perturbation shifting across northern Quebec through the Newfoundland and Labrador vicinity. It appears that a deepening surface cyclone will accompany this feature, with a trailing cold front advancing across much of the Northeast by late Saturday night, while stalling across the Ohio Valley. The shallow leading edge of the cold air, surging to the lee of the Rockies, may advance through the Texas South Plains and Red River vicinity by 12Z Saturday before slowing, as a series of short wave impulses dig within strong north-northwesterly flow across the western Canadian Arctic through Canadian Prairies, and larger-scale positively-tilted troughing in another branch digs across the Great Basin/Southwest. Above this cool air, models indicate that a southerly return flow of moisture will contribute to destabilization in a corridor from the Texas South Plains/western North Texas toward the Mid South by Saturday morning. While it appears destabilization will be limited by relatively warm temperatures/weak lapse rates in mid/upper-levels, thermodynamic profiles probably will still become supportive of weak thunderstorm activity. Aided by weak large-scale forcing for ascent, this may be ongoing at 12Z Saturday and persist through midday, before shifting into the Ohio Valley and weakening. Guidance suggests that additional elevated thunderstorm development, focused along the frontal zone a bit further aloft, is possible across parts of northern Oklahoma/southern Kansas by Saturday afternoon, before perhaps spreading east-northeastward. However, forcing for this activity remains a bit more unclear. ....Pecos Valley into Sacramento Mountains... The dryline could become a focus for modest boundary-layer destabilization, including CAPE on the order of 1000 J/kg, by late Saturday afternoon, in the presence of sufficient deep-layer shear for updraft rotation. An isolated supercell or two might not be out of the question near the southeastern New Mexico/west Texas state border vicinity. However, due to uncertain large-scale forcing for ascent and model spread, the severe weather risk still appears highly conditional and severe weather probabilities are being maintained at less than 5 percent, at least for now. ...Kerr.. 10/27/2023 $$ = = = 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) .