Forecast Discussion
847 FXUS64 KMEG 132306 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 606 PM CDT Tue May 13 2025 ...New AVIATION... .KEY MESSAGES... Updated at 606 PM CDT Tue May 13 2025 - After several days of rain showers and cooler temperatures, sunny, humid and warm conditions will prevail Wednesday and Thursday. Thursday should see the warmest daytime temperatures, with highs in the upper 80s to around 90 degrees. - Scattered showers and thunderstorms will return Thursday night, along and north of the Interstate 40 corridor. Severe thunderstorm chances will increase Friday evening into the early morning hours Saturday. - Unsettled weather will continue through the weekend and early next week, as warm and humid conditions provide favorable conditions for thunderstorms. && .DISCUSSION... (This evening through next Monday) Issued at 317 PM CDT Tue May 13 2025 The upper low that brought showers and cooler temps over the past several days was in the process of lifting out of the region this afternoon. GOES water vapor imagery showed the upper low centered over northern Middle TN, with a secondary lobe noted over east central MO. This latter feature may bring isolated showers around the backside of the departing low. In the interim, scattered showers and perhaps a thunderstorm or two continue east of Memphis until surface instability wanes toward sunset. A warming trend remains on track through Thursday, as a ridge axis lifts through the MS River Valley. This feature will be progressive in nature due to upstream height falls. Latest global model consensus brings the ridge axis through the Midsouth Thursday morning. Southwesterly flow aloft follows for Thursday afternoon around the periphery of a deep northern branch low over the northern Great Plains. GFS and ECMWF soundings depict a stout elevated mixed layer (EML) across the Midsouth Thursday afternoon, capping thunderstorm development. The EML may briefly weaken Thursday evening with modest height falls, but only just so. GFS and ECMWF soundings depict dry air persisting below 650mb late Thursday night. Below the EML, a nocturnal inversion should preclude surface-based convection. In summary, Thursday night`s severe threat appears marginal at best, mainly confined to areas near the MO bootheel and TN/KY border. The EML remains on Friday, but steeper height falls over the mid- MS River valley Friday evening will likely suppress the EML to the southeast, while a surface front sags into the Midsouth. Relative to yesterday`s guidance, this scenario unfolds later in the day Friday into early Saturday, when effective CAPE is progged at 1000-1500 J/kg, down from the 4000 J/kg Friday afternoon. Midlevel lapse rates late Friday evening still appear steep, at 7-8 C/km. The bottom line: CAPE will likely be adequate for severe storms Friday evening into early Saturday morning, while effective bulk shear of 40-50 kt provides organization and persistence potential. Primary threat will be large hail associated with discrete storm clusters. ECMWF indicates a transition to a damaging wind threat early Saturday morning with a belt of 50kt 700mb winds. Unsettled weather remains over the weekend, into early next week. Another storm complex will likely lift out of the southern plains Saturday night. Thereafter, model timing differences begin to emerge with respect to a deep longwave trough over the western states. While the main storm track early next week remains in doubt, positive midlevel height anomalies point toward continued warmer than normal temperatures for the Midsouth. At the surface, a modified tropical maritime airmass will provide ample instability for any storms that develop or move into the Midsouth. PWB && .AVIATION... (00Z TAFS) Issued at 606 PM CDT Tue May 13 2025 VFR conditions currently. Some patchy fog will develop overnight, but coverage is uncertain. There is a low chance of showers (< 20%) tomorrow morning, but not enough confidence to include at any terminals this time. With this potential, some MVFR cigs could move through the airspace mainly between 12Z and 18Z. Light, S/SE winds overnight, picking up in speed around to after 12Z. Could see some occasional gusts upwards of 20 kts by tomorrow afternoon, with winds falling back below 10 kts near the end of the current TAF period. && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$ PUBLIC FORECAST...PWB AVIATION...CMA