Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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989 FXUS64 KHUN 301851 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 151 PM CDT Tue Apr 30 2024 ...New NEAR TERM, SHORT TERM... .NEAR TERM... (Tonight) Issued at 151 PM CDT Tue Apr 30 2024 In wake of the frontal boundry, cloud cover has scattered out with only bands of Cu lingering across the area as rain tapered off. A few rogue and very light rain showers continue to linger over the Cumberland Plateau -- but otherwise dry weather will be the rule through the remainder of the day. By this evening/overnight, high pressure will begin to settle into the Tennessee Valley. In turn, cloud cover will dissipate with the loss of heating and a mostly clear/calm night is forecast as temperatures drop back into the mid to upper 50s in most locations. The clear/calm conditions will create an environment favorable for patchy fog development due to the moist boundary layer conditions. This will especially be true in sheltered valleys and along/near bodies of water -- and have maintained a mention of this in the grids. && .SHORT TERM... (Wednesday through Thursday night) Issued at 151 PM CDT Tue Apr 30 2024 High pressure will become established across the Tennessee Valley Wednesday and Thursday, promoting mostly sunny and dry conditions both days. In fact, a pronounced warm-up will take place, especially by Thursday as the mid/upper ridge axis begins to amplify and winds veer to a southerly direction. In response, highs will climb into the mid 80s on Wednesday and the mid to upper 80s again on Thursday. It`s not completely out of the realm of possibility that a couple of sites reach the 90 degree mark (ensembles hint at about a 10% chance of exceeding that value at both MSL and HSV). Cloud cover will begin to increase by Thursday evening and especially late Thursday night as another mid/upper trough swings into the Great Lakes -- with its associated cold front shifting through the mid/lower Mississippi Valley. Low to medium (20-40%) chances for rain showers (and a few elevated storms) are forecast late Thursday night into Friday morning ahead of the front. QPF amounts are expected to be light, however, as a bulk of the precipitation (and higher rain chances) will move in after 12z Friday. More on this in the section below. && .LONG TERM... (Friday through Monday) Issued at 208 AM CDT Tue Apr 30 2024 The latest suite of global model guidance suggests that the TN Valley will remain beneath a region of light and generally unamplified WSW flow aloft throughout the duration of the extended forecast period, featuring mid-level wind speeds of 25-30 knots at most. In the low-levels a warm/moist airmass will reside across the region, with dewpoints expected to be in the l-m 60s on Friday/Saturday, before perhaps rising into the m-u 60s on Sunday/Monday. This will yield seasonably high values of CAPE (particularly during the afternoon hours, when boundary layer temperatures should rise into the l-m 80s). At this point, it appears as if coverage of showers and thunderstorms will be highest on Friday afternoon/evening, which is the timeframe when a weak cold front may drift southeastward into the CWFA prior to stalling. The front may indeed remain in the region for much of the day on Saturday (warranting a continuation of low-medium chances for showers and storms), before returning northward on Sunday as an amplified trough in the northern stream induces cyclogenesis in the lee of the northern Rockies. Although the atmosphere will be moderately unstable each day, vertical wind shear will not be conducive for the development of organized convection and lightning/locally heavy rainfall should be the primary storm impacts. && .AVIATION... (18Z TAFS) Issued at 1208 PM CDT Tue Apr 30 2024 Cloud cover will continue to break up this afternoon, with a return to VFR conditions expected by mid/late afternoon. Clear conditions will develop by this evening, with light winds. As a result, some light fog may develop late in the period by early Wednesday morning due to the moist boundary layer. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...AMP.24 SHORT TERM....AMP.24 LONG TERM....70 AVIATION...25