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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Wednesday, January 12, 2022

SPC Jan 12, 2022 Day 4-8 Severe Weather Outlook

Day 4-8 Outlook Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0258 AM CST Wed Jan 12 2022 Valid 151200Z - 201200Z ...DISCUSSION... Models are in relatively good agreement regarding severe-weather potential through most of the D4-D8 period, with the primary feature of interest being an intense shortwave trough that will affect the Gulf Coast and southeastern states. Starting on Saturday/D4, a shortwave trough is forecast to drop southeast across the southern Plains, approaching the lower MS Valley by early Sunday/D5. A midlevel jet streak of 80-100 kt will translate from northern TX on Saturday/D4 toward the north-central Gulf Coast by 12Z Sunday, with associated height falls. This wave and associated jet max will then pivot east toward the Carolinas during the day on Sunday/D5 before moving offshore, as an upper low deepens over PA into Monday/D6. The primary factor influencing severe potential with this system will be boundary-layer moisture quality. Models such as the ECMWF (which has good run-to-run consistency) continue to show only a narrow plume of 50s to lower 60s F dewpoints ahead of a rapidly moving cold front. This front and surface low will move across LA and southern MS during the day on Saturday/D4, reaching western GA and the FL Panhandle by 12Z Sunday. Mid-60s F dewpoints may eventually reach the FL Straits late Sunday/D5, just prior to the cold front moving across FL. Forecast soundings reveal very little MUCAPE present ahead of the cold front over the weekend. Further, low-level lapse rates are forecast to be so poor as to not even favor a strongly forced/low-CAPE severe event, despite the strong shear. This is due to the antecedent surface ridge over the Southeast, with insufficient time to warm prior to the next front. Since the only limiting factor will be instability, subsequent model runs will be monitored closely for either 1) A slowing of the upper trough (which would allow more time for airmass recovery), or 2) A faster return of mid/upper 60s F dewpoints which may lead to sufficient SBCAPE. As such, potential is currently too low for a 15% or greater severe probability during the Saturday/D4 through Sunday/D5 period. As the event nears in time, lower severe probabilities may still be added, should the parameters remain as currently forecast. Beyond Sunday/D5, it appears a stable air mass will remain over much of the East due to high pressure, with only gradual dewpoint recovery across the Gulf of Mexico as the flow regime aloft becomes more zonal. Read more CHECK UPDATE ZOOM GRAPHIC