Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue May 09 2023 17:28:29 ACUS02 KWNS 091728 SWODY2 SPC AC 091727 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Tue May 09 2023 Valid 101200Z - 111200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER THE CENTRAL HIGH PLAINS REGION... ....SUMMARY... Scattered strong to severe storms -- capable of producing damaging winds and hail, and potentially a couple of tornadoes -- are expected Wednesday afternoon and evening within an area centered over the central High Plains. ....Southeast MT south to the OK/TX Panhandles... An upper trough over the western U.S. will shift east across the Four Corners vicinity toward the central/southern High Plains on Wednesday. As this occurs, meridional/southerly mid/upper level flow will modestly increase over the southern/central Rockies and adjacent High Plains vicinity. At the surface, a weak low/trough will extend southward from near the Palmer Divide to the NM/TX border. Southeasterly low-level flow will maintain modest boundary-layer moisture over the region with dewpoints generally in the 50s F. Near-60 F dewpoints are possible further east toward western NE/KS. Steep midlevel lapse rates (7.5-8.5 C/km) atop this modest boundary-layer moisture will support weak to moderate destabilization. Some model discrepancy is apparent over portions of southwest NE/northwest KS/northeast CO vicinity with the 12z NAM maintaining a much cooler airmass compared to other guidance. This is likely due to placement of morning convection and outflow related to storms in the Day 1 period. This lends to quite a bit of uncertainty in convective evolution in the Day 2 period. Nevertheless, convection is expected to develop near higher terrain during the early/mid-afternoon and spread east/northeast across eastern WY/CO and into SD/NE/KS by evening. Additional more isolated convection also is expected to develop along the surface trough over the southern High Plains. Initially, large hail will be the main hazard with more discrete storms. However, where stronger surface heating occurs, damaging gusts also will be possible. Some upscale development into clusters/bows may increase wind potential with time and eastward extent as well. The tornado risk is more uncertain. Low-level flow will generally be weak with northward extent and the more meridional flow is producing vertical shear profiles less favorable for tornadoes. The greatest relative risk will likely be confined to northeast CO and vicinity where backed low-level flow and somewhat stronger vertical shear is forecast. If the cooler, more capped solution presented by the NAM unfolds, the tornado risk may be diminished even across this area. ....Northeast ND into northern MN... A shortwave impulse is forecast to move atop the northern Plains/Upper Midwest upper ridge near the international border through the afternoon/evening. This will allow for a belt of enhanced westerly flow to overspread the region atop modest boundary-layer moisture (surface dewpoints in the 50s F). Forecast soundings indicate modestly steep midlevel lapse rates (around 7 C/km), aiding in weak destabilization (750-1000 J/kg MLCAPE). Thunderstorms are expected to develop along a southeastward-advancing front initially over Manitoba and spread southeast into northeast ND and northern MN. Vertically veering wind profiles will result in marginal effective shear magnitudes around 30 kt, allowing for organized cells despite rather low/midlevel flow. Elongated, straight forecast hodographs coupled with modest instability suggest marginally severe hail is possible with this activity as it spreads east/southeast near the international border from late afternoon into the evening hours. ....Southeast TX/Western LA vicinity... An upper ridge is forecast to extend from the TN Valley/Central Gulf Coast vicinity, north/northwest toward the Upper Midwest on Wednesday. A weakness/shortwave impulse within the western periphery of the eastern U.S. upper ridge will migrate across TX toward the Lower MS Valley. At the surface, a weak low/MCV is forecast in the vicinity of east-central TX Wednesday morning. This feature will lift north/northeast through the day. A few strong storms are possible within broader area of precipitation/ongoing MCS during the morning across southeast TX/Upper TX Coast. Additional convection and locally strong storms also will be possible through the afternoon across southeast TX toward the Sabine River and perhaps as far north as the ArkLaTex vicinity on the eastern periphery of the low/MCV. However, widespread cloudiness/persistent precipitation will limit heating and destabilization through the day. Some enhancement of otherwise modest vertical shear by the low/MCV may support transient strong/organized cells. Sporadic strong gusts will be the main hazard with this activity through the afternoon. ...Leitman.. 05/09/2023 $$ = = = 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) .