Area Forecast Discussion
Issued by NWS Memphis, TN
Issued by NWS Memphis, TN
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101 FXUS64 KMEG 212035 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 335 PM CDT Tue May 21 2024 ...New SYNOPSIS, DISCUSSION... .SYNOPSIS... Issued at 327 PM CDT Tue May 21 2024 A ridge of high pressure will weaken tonight with a cold front bringing a return of shower and thunderstorm chances back to the Mid-South. A strong to severe thunderstorm is possible across portions of northeast Arkansas and the Missouri Bootheel late tonight, However, the greatest potential for severe thunderstorms will be Wednesday afternoon into Wednesday night across the Mid- South. Damaging winds will be the primary severe weather threat with a secondary threat of large hail, heavy rainfall, and possibly a tornado. A period of unsettled weather will persist across the Mid-South beginning late tonight and continuing through early next week. && .DISCUSSION... (This evening through next Monday) Issued at 327 PM CDT Tue May 21 2024 GOES-16 Water Vapor Satellite trends this afternoon show a mid- level trough moving into the Upper Midwest, an elongated upper-level ridge present from the Great Lakes Region back through the Southeast U.S. and portions of the Lower Mississippi Valley. This has resulted in another warm and dry afternoon with temperatures in the middle to upper 80s as of 2 PM CDT. Strong to severe thunderstorm potential will remain the predominant concern in this afternoon`s forecast issuance, especially for the next two days. Short-term models indicate the aforementioned upper-level ridge will begin to break down tonight across the Lower Mississippi Valley with 20-30 dm 500 mb height falls occurring north of I-40. A mid-level shortwave trough and associated cold front will drop into the Mid-South late tonight into Wednesday morning bringing a return of showers and thunderstorms back to the area. Short-term models, particularly the operational CAMs have struggled with the overall evolution of convection across the Mid-South into Wednesday night. Nonetheless, a broken convective line is expected to gradually weaken north of I-40 overnight. Steep 700-500 mb mid-level lapse rates, surface-based CAPE values, and 0-6 km bulk shear values between 40-45 kts suggest a potential for strong to severe thunderstorms initially with damaging winds and large hail being the severe weather threats until the storms become elevated late in the night. This weakening convection is expected to leave behind outflow boundaries which may interact with with an MCS/MCV to produce redevelopment of showers and and thunderstorms across the Mid- South Wednesday afternoon into Wednesday evening. Large hail and damaging winds will continue to be the primary severe weather threats, with a secondary threat of heavy rainfall as precipitable water values will remain high. A tornado or two may be possible if there is enough streamwise vorticity available in the pre- convective environment as can be the case with MCVs. Operational and ensemble model runs indicate an unsettled pattern will persist for Thursday through early next week as the aforementioned cold front washes out over the Lower Mississippi Valley and another front drops into the region for Memorial Day. Additional strong to severe thunderstorms are possible during this period, especially for portions of the forecast area Thursday and again on Sunday. CJC && .AVIATION... (18Z TAFS) Issued at 1237 PM CDT Tue May 21 2024 VFR this afternoon with gusty south winds at 12-20 kts with higher gusts. Winds will diminish some this evening though remain above threshold at MEM. First round of TSRAs should push into the area later tonight and early Wednesday. Expect low clouds across much of the area Wednesday morning. The first round of storms will leave behind outflow boundaries that will influence the next round convection expected Wednesday afternoon. Timing of the convection remain difficult with the 12z CAMs offering a variety of solutions. && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$ PUBLIC FORECAST...CJC AVIATION...SJM