Sunrise 5:53 AM   Sunset 7:40 PM Moonrise 4:19 AM   Moonset 5:07 PM

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FXUS64 KHUN 050548 AFDHUN

Area Forecast Discussion National Weather Service Huntsville AL 1248 AM CDT Sun May 5 2024

New AVIATION

NEAR TERM
(Rest of tonight)
Issued at 934 PM CDT Sat May 4 2024

More tranquil weather has returned across the Tennessee Valley, as convection over our eastern areas have exited to the east. Other showers were in progress over the Ozarks and fading over western Mississippi. 9 PM temperatures have cooled into the upper 60s to lower 70s, after earlier rising into the upper 70s and lower 80s.

Unlike last night, skies across the region were mostly clear, with a few passing cirrus clouds. Thus with a moist surface, the clear skies, light winds, lower rain chances and the night-time; brings a risk of fog developing. Model MOS guidance was showing this, especially the GFS and GFS-based LAMP, while the older NAM was only showing patchy fog at best. When refreshing the grids with newer blended guidance (and lower rain chances/coverage) this has generated more fog in the overnight. That said, I am not too inclined for a Dense Fog Advisory at this time with shorter nights and some inherent instability that could result in a stray shower or two forming. Do have patchy to areas of fog in the grids, based on new dewpoints and minor temperature adjustments.
Other places more subject for fog would be locations that received measurable rainfall the past day or so, and those more sheltered locations. Low temperatures otherwise should cool into the low/mid 60s by daybreak Sunday.

SHORT TERM
(Sunday through Tuesday)
Issued at 319 PM CDT Sat May 4 2024

As a stronger disturbance moves north-northeast from northeastern Texas and central Oklahoma late Saturday night into Sunday morning, a warm front ahead of it moves northeast into northern Arkansas by the mid-afternoon hours. Models form robust convection along this warm front. However, most models only develop this convection as far east as Mississippi through the afternoon hours.
This is a good thing given the sounding parameters further east into northern Alabama. This will likely keep any severe thunderstorm activity to the west of the area through the afternoon hours.
Models do push this warm front further north into northwestern Alabama between 7 and 9 PM. However, models really drop off instability these storms have to work with during that timeframe.
Shear continues to be too weak to support any severe weather.
Gusty winds, frequent lightning, and heavy rainfall could occur as this weakening convection moves into the area and across northern Alabama and southern middle Tennessee overnight. If this activity along this warm front moves in sooner than expected, then a severe downburst or large hail threat might materialize. However, this is not expected as mentioned before.

Models weaken this upper level disturbance and have it move more to the east Monday into Monday night. Not expecting as widespread or strong thunderstorm activity this far south, with the main energy with this disturbance remaining more over northern Tennessee into the Ohio Valley. However, high chance to likely chances of showers and thunderstorms should still remain in the forecast through the day on Monday.

A drier pattern with zonal flow aloft is in place Monday night through Wednesday. Very strong warm air advection develops ahead of a strong cold front that develops over the central CONUS on Tuesday. 925 mb temperatures between 23 and 26 degrees are advected into the area ahead of the developing cold front well to our west. This should allow temperatures to climb into the mid to upper 80s during this period in the afternoon, despite some isolated to scattered showers and thunderstorms. We could see some highs around 90 degrees on Wednesday, but kept things a tad cooler for now. These isolated to scattered showers or thunderstorms should remain fairly unorganized, given low shear value and lack of drier air aloft.

LONG TERM
(Wednesday night through Saturday)
Issued at 319 PM CDT Sat May 4 2024

The more reasonable scenario for Wednesday evening into Thursday continues to look like an MCS ahead of that stronger cold front reaching our region by Wednesday evening. In this case, redevelopment of thunderstorms would occur along the path of the surface low (across MO) early Wednesday afternoon that could potentially grow upscale into a larger and more significant MCS that would move through our region late Wednesday night/early Thursday morning. This convective system would be entering an environment of even stronger deep-layer shear (with WSW flow aloft of 45-50 knots) and moderate-high levels of instability driven by surface dewpoints in the lower 70s beneath a plume of steep lapse rates aloft. Thus, a notable risk of severe thunderstorms producing large hail and damaging winds may materialize during this timeframe. A third and final round of storms may occur on Thursday night/Friday morning prior to the eventual passage of a cold front that should bring a drier/cooler airmass into the region by next weekend.

AVIATION
(06Z TAFS)
Issued at 1248 AM CDT Sun May 5 2024

Isolated-widely sct SHRA/TSRA which developed to the immediate N/E of HSV late Sat evening will continue to progress eastward, and should not impact the airport. However, with mostly clear skies and calm winds anticipated for much of the early morning period, abundant low-lvl moisture will support the development of MVFR vsby reductions in lgt BR/FG, and this has been included in TEMPO groups at both HSV/MSL from 9-13Z. A diurnal Cu field will redevelop by 16-18Z, with isolated showers and storms possible invof the terminals once again beginning early this aftn. That said, a more widespread coverage of rain and TSRA will likely begin across northwest AL very late this aftn and spread northeastward with time during the evening hours, potentially bringing MVFR cigs/vsby in pockets of locally heavy rainfall.

HUN WATCHES/WARNINGS/ADVISORIES
AL...None.
TN...None.

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