Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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153 FXUS64 KHUN 031901 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 201 PM CDT Fri May 3 2024 ...New NEAR TERM, SHORT TERM... .NEAR TERM... (Tonight) Issued at 202 PM CDT Fri May 3 2024 Pop up summer like convection has begun to develop across the area with the highest coverage of scattered showers currently in NW AL. With an incredibly moist tropical air mass in place, isolated to scattered showers and thunderstorms will easily be supported through the evening ahead of the next shortwave. Higher coverage of showers and storms will move in from the SW as as the aformentioned shortwave ripples NE through the area. Higher rainfall chances look to pick up around 5 PM in NW AL and around 8 PM in NE AL. Uncertainty remains in coverage of showers and storms as the shortwave moves through. What seems likely at this point is a cluster of scattered rain and storms moving into NW AL and continuing east throughout the night. CAMS continue to diverge on solutions with the passage of the shortwave with some models showing widespread light to moderate rain and others showing corridors of heavier rain for same and dry conditions for others. With such a moist boundary layer and a few hundred J/KG of CAPE all storms will be capable of producing frequent lightning and heavy downpours. Areas that do see better storm coverage will likely see high convective rainfall rates that could produce ponding of water and localized nuisance flooding in urban and flood prone areas. The shortwave and associated showers and storms looks to move out in the early morning hours with low rain chances lingering into Saturday. && .SHORT TERM... (Saturday through Monday) Issued at 202 PM CDT Fri May 3 2024 Saturday, and the remainder of the short term, offers the same forecast challenges. A weak syntopic pattern remains in place with broad mid level ridging to our east allowing for subsequent shortwaves to ripple through the area. The passage of a shortwave tomorrow afternoon will again trigger our highest chances and highest coverage of rain and storms. Once again, tricky pop up convection remains a possibility starting in the late morning ahead of the shortwave. This pattern continues on Sunday into Monday as a mid level trough in the Plains pushes at least two more shortwaves through the area. This will maintain medium to high PoPs across the CWA with highest coverage of rain and storms reserved for each afternoon. While each day will pose a threat for frequent lightning and heavy rainfall, no severe weather is anticipated through the duration of the short term. As for anticipated rainfall, overall weekend QPF amounts will likely vary greatly in spatial coverage. With favorable environmental factors in place for efficient rainfall production, showers could easily dump a quarter to a half inch in a brief period of time for isolated areas. While this alone is not enough to raise flooding concerns, periods of heavy rainfall could continue to trigger ponding of water and nuisance flooding for urban area. When it`s not raining, the tropical airmass will make for a very humid weekend. Highs remain in the low 80s with dewpoints in the high 60s each day. && .LONG TERM... (Monday through Thursday) Issued at 433 AM CDT Fri May 3 2024 After warm frontal convection spreads northeastward and out of the region late Monday morning, the TN Valley will be solidly within a very warm/moist tropical airmass, with dewpoints expected to rise into the m-u 60s as southwesterly low-level flow strengthens. Although this will contribute to greater instability (especially during the afternoon hours), a mid-level ridge will shift across the region downstream from the central Rockies upper low as it begins to spread northeastward into the northern Plains, and this should yield a lower coverage of mainly afternoon thunderstorms from Monday-Wednesday. Overnight lows will steadily increase into the u60s-l70s through the middle of next week (due to both elevated SW winds and moisture advection), with highs also warming into the mid (to perhaps upper) 80s by Wednesday. Although details are unclear at this time range, conditions will become more favorable for convection at the end of the extended period (Wednesday night/Thursday), perhaps in the form of MCS activity that may initiate along a cold front to our northwest and propagate southeastward into the local area. Should this scenario materialize, conditions will be favorable for organized severe thunderstorms across our region, with boundary layer dewpoints in the u60s-l70s beneath a belt of mid-level WSW flow of 35-45 knots. && .AVIATION... (18Z TAFS) Issued at 1230 PM CDT Fri May 3 2024 Afternoon pop up convection will make for challenging TAFs. Scattered showers and thunderstorms are likely to develop through the afternoon from surface heating. Kept VCTS in the prevailing to account for uncertainty in storm coverage and intensity. Later this evening, just before 0Z, more widespread showers and storms will move in from the west. This will result in heavier showers with periods of MVFR to IFR possible as reflected in the tempo group. While strongest showers and storms will move out of the area during the early morning hours, MVFR ceilings will likely remain for the duration of the TAF period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...RAD SHORT TERM....RAD LONG TERM....70 AVIATION...RAD