Area Forecast Discussion
Issued by NWS Memphis, TN
Issued by NWS Memphis, TN
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119 FXUS64 KMEG 041543 AFDMEG Area Forecast Discussion National Weather Service Memphis TN 1043 AM CDT Thu Jul 4 2024 ...New UPDATE... .UPDATE... Issued at 1042 AM CDT Thu Jul 4 2024 A few high and mid-level clouds are apparent on satellite as of 10:30 AM. Temperatures are in the upper 80s and lower 90s with dewpoints nearing 80 degrees across the region. Dewpoints are running a few degrees cooler this morning allowing only a few locations across the area to have already exceeded Heat Advisory criteria. A leading shortwave will eject ahead of the longwave trough this afternoon and initiate scattered thunderstorms mainly across west Tennessee and north Mississippi. Later this evening the longwave trough will approach and bring showers and thunderstorms to northeast Arkansas, the Missouri Bootheel, and northwest Tennessee where a Slight Risk for severe weather is in place. Confidence is low for severe weather impacts this afternoon and evening as best severe weather parameters remain surface based aided by daytime heating. Once daytime heating runs out it will be even more difficult for storms to sustain their updrafts. Nonetheless, coverage looks much better than yesterday with 0.5"-1.0" of rain expected. Previous forecast remains in good shape, adjusted PoPs and dewpoints. DNM && .SYNOPSIS... Issued at 305 AM CDT Thu Jul 4 2024 Hot and humid conditions will remain for your Fourth of July holiday as heat index values climb greater than or equal to 110 across the area. As a result of these dangerous heat indices, an Excessive Heat Warning is in affect for the entire Mid-South today. Dangerously hot conditions will suggest limiting outdoor activities today. A few strong to severe storms may be capable of producing damaging winds and localized heavy rainfall this afternoon and into the overnight hours. A brief lull in precipitation will exist Saturday and Sunday as high pressure moves across the area. Rain chances will ramp up once again Monday through through at least mid-week. As a result of increased rainfall, temperatures will be a bit cooler Friday and into next week. && .DISCUSSION... (Today through Wednesday) Issued at 305 AM CDT Thu Jul 4 2024 Another warm night is on display at this hour as current temperatures are in the upper 70s to low 80s with mostly light winds at the surface, under mostly clear skies areawide. We remain fixed under a 596 dm subtropical ridge resulting to hot and humid conditions across the entire Mid-South. Dewpoints remain on the uncomfortably high end with current dewpoints in the upper 70s as southerly winds continue to usher in moisture. This is not a good sign for heat indices for our Fourth of July holiday activities. Current forecast afternoon dewpoints will continue to increase into the upper 70s to low 80s areawide. As a result, heat index values >=110 F will be analyzed across our entire area today. An Excessive Heat Warning is in affect for our the entire Mid-South through 9 PM tonight. A weak cold front will push across the region tomorrow morning, as the ridge builds south/southeast, decreasing our daily highs into the upper 80s to low 90s through mid-week. The aforementioned heat and humidity will also provide ample instability for convection today. Shower and thunderstorm chances will continue to increase later this morning as a few short waves continue to dampen the ridge over northeast Arkansas, the Missouri Bootheel, and portions of northwestern Tennessee. As heights fall this afternoon and into the evening hours, convection looks to ramp up over areas mainly north of the I-40 corridor. A few multi-cell clusters look to form and enter into an environment of around 2500-3000 J/kg of surface based CAPE and around 20-25 kts of 0-6 km Bulk wind shear ahead of the aforementioned cold front. PWATs will also be around 2-2.25", nearing the 90th-97th percentile for this time of year. Bottom line, a conditional chance for severe weather exists this afternoon and through the early overnight hours with primary threats of damaging winds and localized heavy rainfall. As the aforementioned cold front moves through Friday, PWATs continue to soar upwards of 2.25 inches (nearing the 97th percentile). Large rainfall rates will result in a localized heavy rainfall threat for Friday. A brief lull in precipitation looks to exist Saturday and Sunday as high pressure and quasi-zonal flow looks to move over the region. Showers and thunderstorms will head back into the forecast Monday morning as a positively tilted trough axis looks to push in from the West with a possible combination and lift from Hurricane Beryl. Though uncertainty remains high on onset impacts, showers and thunderstorms remain in the forecast through at least mid-week. Stay tuned. AEH && .AVIATION... (12Z TAFS) Issued at 648 AM CDT Thu Jul 4 2024 Convective inhibition will weaken through the afternoon. Weak shear and outflow interactions limit confidence in TSRA timing and location. Temporal overlap of modest midlevel height falls and convective instability will likely support scattered TSRA between 21Z and 03Z, but isolated TSRA will be possible outside this time frame. A second TSRA episode is anticipated overnight with continuing midlevel height falls, modest low level jet and approaching surface cold front. Generally followed HRRR and TCF on TSRA timing late tonight. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...Excessive Heat Warning until 9 PM CDT this evening for ARZ009- 018-026>028-035-036-048-049-058. MO...Excessive Heat Warning until 9 PM CDT this evening for MOZ113- 115. MS...Excessive Heat Warning until 9 PM CDT this evening for MSZ001>017-020>024. TN...Excessive Heat Warning until 9 PM CDT this evening for TNZ001>004-019>022-048>055-088>092. && $$ PUBLIC FORECAST...DNM AVIATION...PWB