FXUS64 KMEG 021555 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 1055 AM CDT Fri May 2 2025 ...New MESOSCALE UPDATE... .KEY MESSAGES... Updated at 1018 AM CDT Fri May 2 2025 - Severe thunderstorms will be possible over the Midsouth today. During the early morning, large hail will be the primary severe threat, mainly west of the Mississippi River. After midmorning, damaging winds will become the primary severe weather threat. - Scattered showers and perhaps a few thunderstorms will continue late tonight through Sunday afternoon, mainly to the north and east of Memphis. - Cool temperatures will prevail Saturday through early Monday. Most of the Midsouth will see highs in the 60s Sunday, and lows in the upper 40s Sunday night. && .MESOSCALE UPDATE FOR SEVERE THUNDERSTORMS... Issued at 1054 AM CDT Fri May 2 2025 GOES Satellite trends show an MCV moving across the Lower Mississippi Valley late this morning. Regional WSR-88D radar trends indicate the first cluster of showers and thunderstorms beginning to approach the Tennessee River. A second area of convection is over central Arkansas and beginning to approach areas west of the Mississippi River. Latest mesoanalysis indicates surface-based CAPE values at or above 2000 J/kg near the Tennessee River, and across much of north Mississippi and east Arkansas south of I-40. This instability combined with 0-6 km Bulk Shear values around 40 kts, and moderately steep to steep mid-level lapse rates will support the potential for severe thunderstorms into this afternoon. Damaging winds and large hail are the main threats for any thunderstorms that become severe. Probabilities for tornadoes remain very low given less than ideal hodographs. Severe thunderstorm potential across portions of extreme northeast Arkansas and the Missouri Bootheel is somewhat lower given less than ideal instability. && .DISCUSSION... (Today through Thursday) Issued at 415 AM CDT Fri May 2 2025 The primary forecast concern remains thunderstorm coverage and timing through this evening. An east/west band of storms had formed along an elevated warm front over central AR early this morning. These storms were semi- discrete, presenting a marginal hail threat as they lifted northeast. 06Z HRRR depicted ample mixed layer CAPE, in excess of 2500 J/kg over much of the Midsouth by late morning. A belt of 50+kt 700mb winds are depicted along and north of the I-40 corridor by midday, coinciding with 0-6 km bulk shear of 45+ knots. However the 06Z HRRR missed the aforementioned early morning storms over AR, limiting confidence in short term convective evolution. Where the airmass isn't modified, midlevel lapse rates around 7.5 C/km will support large hail where storms remain discrete. The steep lapse rates will weaken through the morning, and expect the primary threat to shift to damaging winds as the stronger kinematics arrive. The wind threat will push to the TN River by mid-afternoon. With the continuation of upstream height falls, the severe weather threat will shift south of I-40 this evening, focused near an advancing surface cold front. Severe threat should end over northeast MS mid/late evening, as the low level warm sector moves into AL. The Midsouth will remain under an upper level cut-off low through the weekend. This low will be centered over the mid-Mississippi and lower Ohio River Valley, and will constitute the eastern leg of an Omega blocking pattern. Diurnally-enhanced showers will be possible under this low, especially to the north and east of Memphis through Sunday. Cloud cover and cold air aloft will result in surface temperatures around 10 degrees below normal. The Omega blocking pattern will shift slightly east early next week, placing the Midsouth under brief ridging aloft on Tuesday. Tuesday's highs should average near normal. Medium range guidance is consistent in depicting an ejecting shortwave from Texas into the lower MS River Valley Tuesday night. With PWATs around 1.8 inches and diffluent flow aloft, thunderstorms and locally heavy rainfall will be possible, especially south of I-40. Unsettled weather will likely continue late next week, as the western U.S. upper low moves into the Great Plains and the Midsouth remains under the subtropical branch of the upper jet. PWB && .AVIATION... (12Z TAFS) Issued at 643 AM CDT Fri May 2 2025 An upper low pressure system will bring several distinct rounds of SHRA/TSRA over the next 18 hours or so. The first wave of ongoing thunderstorms is associated with an elevated warm front. This will be closely followed by the main event, a large bowing thunderstorm segment along the cold front that will push through early afternoon. After the main line of thunderstorms has exited the region, a broad area of showers will rotate about the upper low as it tracks directly over the airspace. These three distinct features are the reason the precip groups in the TAFs at all sites are quite messy. With respect to ceilings, confidence in post-frontal IFR increases the farther east you go. Have not included anything lower than MVFR at MEM for now but there may be a brief 2-3 hour window after 00Z tonight where CIGs drop below 1 kft. Overall, the general trend of ceilings is VFR through midday and a gradual decline to MVFR/IFR as the upper low approaches this evening. Winds generally remain southwesterly 5-10 kts through tomorrow morning. Behind the front, a gradual shift around to the northwest will take place after sunrise Saturday as all sites return to VFR. CAD && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$ MESOSCALE UPDATE...CJC PUBLIC FORECAST...PWB AVIATION...CAD