Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 11 2023 17:32:25 ACUS02 KWNS 111732 SWODY2 SPC AC 111731 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Sun Jun 11 2023 Valid 121200Z - 131200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE LOWER MS VALLEY INTO THE CENTRAL GULF COAST...AND ACROSS NORTHWEST/NORTH-CENTRAL TX... ....SUMMARY... Severe thunderstorms are expected during the afternoon and evening across northwest into north-central Texas, with very large hail as the main risk. Severe thunderstorms are also expected from the Lower Mississippi Valley into the central Gulf Coast, with damaging gusts as the primary risk. ....Synopsis... Upper pattern across the CONUS will feature a pair of cyclones early Monday morning, one centered over the Upper Great Lakes and the other one centered over the Great Basin. The Upper Great Lakes cyclone is forecast to slowly drift eastward towards Lower MI, while deepening slightly. A pair of shortwave troughs are expected to rotate through this cyclone, with the lead wave progressing eastward/northeastward through the Mid-Atlantic and Northeast states. The following wave will likely move across the OH Valley Monday afternoon/evening, reaching the Lower Great Lakes vicinity early Tuesday morning. The western cyclone is forecast to weaken as it moves into the Four Corner region, with shortwave troughs expected to move through its base as well. The lead wave should move through the southern High Plains and into the central Plains during the period, while the wave in its wake moves across southern CA and into AZ from Monday afternoon into early Tuesday morning. Strong mid-level flow will extend throughout the base of this cyclone, and is expected to expand into the southern Plains throughout day. Stronger flow is expected through the base of the Great Lakes cyclone as well, and the combination of these areas will result in a corridor of enhanced mid-level flow from northern Baja/northern Mexico across the southern Plains, Mid-South, and TN Valley, and off the Mid-Atlantic coast by early Tuesday morning. The surface pattern on Monday will be dominated by two features, strong ridging over the northern and central Plains, and a low and associated front over the eastern CONUS. The surface low will begin the period over the Lower Great Lakes before drifting northward and further occluding. The associated cold front is forecast to continue progressing eastward, interacting with the moist air mass in place along the Eastern Seaboard. Additionally, the boundary between the drier continental air mass associated with the ridging and more moist air mass in place across the southern Plains and Southeast is expected to sharpen, particularly over TX. ....Northwest into North-Central Texas... Strong buoyancy (i.e. MLCAPE over 3000 J/kg) is forecast to develop over the TX Big Country, near a triple point low at the intersection of the stalled surface front and dryline. Mesoscale ascent associated will this low is expected to result in isolated thunderstorm development during the afternoon. Strong vertical shear is anticipated with hodographs showing supercell wind profiles. Environmental conditions favor very large hail (i.e. greater than 2" in diameter) as the primary risk with initial development. Low-level wind profiles do show veering with height, but flow is generally weak and the storms should be fairly high based. As such, the tornado threat is low, but non-zero, particularly if storms interact with the boundary. Upscale growth is likely, with the resulting line bringing a severe risk farther into north-central TX. Higher probabilities may be needed, but uncertainty regarding coverage limits the confidence to introduce any with this outlook. ....Lower MS Valley into the Southeast... Moderate to strong buoyancy is expected to develop during the afternoon, amid the upper 60s/low 70s dewpoints expected to be in place. Afternoon thunderstorms development appears likely along the cold front pushing into region. Seasonally strong mid-level flow is expected across the region as well. All of these factors will result in a broad area of severe risk. A locally higher severe risk is anticipated from eastern LA into southern AL and western FL Panhandle, where guidance suggests a convectively augmented vorticity maximum will interact with the already favorable environment. Higher wind probabilities may eventually be needed in this area, but low predictability of vort max strength and evolution, and uncertain frontal position currently limit the forecast confidence. ....Colorado Front Range into the TX Panhandle... Boundary-layer destabilization will remain confined to a narrow corridor, along a remnant surface front into the higher terrain, as a lead short wave impulse emerges from the Great Basin. Still, this environment may become favorable for a period of isolated to widely scattered strong/severe thunderstorm development, before convection tends to advect off and away from the higher terrain. ....Mid-Atlantic through the Carolinas... Thunderstorms are expected to develop during the afternoon along the eastward-progressing cold front, with some development possible along any pre-frontal troughing as well. Lapse rates will generally be poor, but afternoon dewpoints in the mid to upper 60s should still support low to moderate buoyancy as the air mass heats up. The stronger mid-level flow will likely arrive during the evening, after the peak thunderstorm coverage, but some stronger storms are still possible, with damaging gusts as the primary risk. Less buoyancy is anticipated across the northern portions of the region, but stronger mesoscale ascent and greater shear near the triple point low could still foster a few severe storms. ...Mosier.. 06/11/2023 $$ = = = 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) .