Area Forecast Discussion
Issued by NWS Memphis, TN
Issued by NWS Memphis, TN
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247 FXUS64 KMEG 251721 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 1221 PM CDT Sat May 25 2024 ...New AVIATION... .UPDATE... Issued at 1019 AM CDT Sat May 25 2024 Dry conditions will persist for the majority of the Mid-South today as shortwave ridging remains aloft. There is potential for storm development this afternoon, mainly in areas of north Mississippi. Storms may reach severe limits at this time, with large hail and damaging winds the main concerns. Severe weather chances increase on Sunday as a shortwave trough pushes across Missouri. Ahead of this system, dewpoints will be in the low to mid 70s with midlevel lapse rates around 7.5 C/km. Uncertainty remains regarding exact timing of storms as 12Z CAMs suggest two waves of activity. The first round of storms looks to impact the region in the afternoon. This round would pose a larger tornado threat as discrete storm mode is possible. Towards the evening and overnight hours, a secondary line of storms will drop across the Mid-South. At this time, low level lapse rates should decrease to around 6 C/km, precluding a large hail threat. Therefore, damaging winds will be the main concern after sunset. ANS && .SYNOPSIS... Issued at 415 AM CDT Sat May 25 2024 Showers and thunderstorms will continue over the Midsouth today, though weak upper level ridging will limit coverage. A few storms may still reach severe limits this afternoon, with large hail and damaging winds the primary threats. Severe weather chances will increase Sunday afternoon over northeast Arkansas, the Missouri bootheel and northwest Tennessee. Large hail, damaging winds and a few brief tornadoes will be possible. The severe weather threat will continue Sunday evening over the remainder of the Midsouth, as storms move to the southeast ahead of an advancing cold front. The storms should exit north Mississippi overnight Sunday night. Less humid weather is forecast across the Midsouth on Memorial Day. Only isolated showers and thunderstorms are expected east of the Mississippi River. && .DISCUSSION... (Today through Friday) Issued at 415 AM CDT Sat May 25 2024 09Z / 4 AM CDT surface map showed a cold front from St. Louis to Joplin, Missouri. A prefrontal pressure trough was located over southeast Missouri. Storms fired late Friday evening near this pressure trough, but have since weakened since moving off the boundary into northeast Arkansas. To the south, a bowing linear MCS has passed from east central Arkansas into west TN. This activity briefly weakened, but intensified as it lifted to the TN River, aided by a 50 KT low level jet. The HRRR and NAM depict a significant reduction in 925mb inflow and storm coverage toward 12Z. Thunderstorm chances for the remainder of the day will limited by weak ridging aloft. This ridging will also serve to displace EML to the north, weakening convective inhibition, especially over north Mississippi. Most of the Midsouth will see midlevel lapse rates moderating below 6 C/km, lessing the large hail threat through tonight. Severe weather chances will return Sunday, as the midlevel ridge lifts off the east. Diffluent flow aloft and midlevel height falls will sufficiently weaken for convection to grow south from an ongoing MCS over the lower Ohio Valley Sunday afternoon. Storms will be likely from northeast Arkansas through northwest Tennessee during peak afternoon heating. HRRR soundings across this area depict midlevel lapse rates 7-8 C/km and surface-based CAPE near 3000 J/kg. Bulk shear near 50 KT should maintain storm organization through the afternoon. Effective SRH values are relatively low but given the CAPE, a few brief spin-ups will be possible along mesoscale boundaries Sunday afternoon. Locally heavy rainfall, aided by PWAT near 1.75 inches is also expected, though storms should remain progressive in movement. Storm chances south of the I-40 corridor will ramp up Sunday evening, as additional height falls aid storm development along a prefrontal outflow boundary. MUCAPE of 2000-3000 J/kg will support a severe threat into north MS after midnight Sunday night. Main severe threat will remain damaging wind. Midlevel lapse rates around 6.5 C/km will support large hail, but the hail threat will likely be limited by a transition to linear convective mode. Tornado threat should decrease through late Sunday evening, as storms become rooted in an elevated layer. Following the exit of storms over north Mississippi early Monday morning, a quieter weather pattern will settle in for at least a couple days. Isolated showers and thunderstorms will be possible on Memorial Day, mainly near the Tennessee River, but suspect NBM PoPs may be a bit on the high side Monday afternoon. Northwest flow aloft will continue through Thursday, with a few storms possibly dropping through eastern Arkansas and north Mississippi around midweek. PWB && .AVIATION... (18Z TAFS) Issued at 1214 PM CDT Sat May 25 2024 VFR conditions should prevail, although a couple of rounds of thunderstorms are possible at MEM this afternoon and again late tonight into early Sunday. Only one round of storms looks more reasonable at TUP which would be this afternoon. At MKL and JBR only one round looks reasonable late tonight into tomorrow. CAMs have struggled, thus uncertainty remains high on both timing and where storms would be most likely. I decided to just go with just VCTS at all sites to cover the aforementioned periods. South to southwest winds below 10kts today and tonight will increase 10-15kts tomorrow with gusts in the low 20s. Cigs should remain VFR at all sites with the exception of brief periods if there is on station TSRA. 30/Sirmon && .MEG WATCHES/WARNINGS/ADVISORIES... AR...Flood Watch through Monday morning for ARZ009-018-026>028-035- 036-048-049-058. MO...Flood Watch through Monday morning for MOZ113-115. MS...Flood Watch through Monday morning for MSZ001>017-020>024. TN...Flood Watch through Monday morning for TNZ001>004-019>022- 048>055-088>092. && $$ PUBLIC FORECAST...PWB AVIATION...JDS