Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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412 FXUS64 KHUN 201801 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 101 PM CDT Fri Sep 20 2024 ...New NEAR TERM, SHORT TERM... .NEAR TERM... (Tonight) Issued at 100 PM CDT Fri Sep 20 2024 A 5h ridge axis will drop southeast into the region tonight as surface high pressure shifts to the lee of the Appalachians and an 8h high becomes centered over central AL. Dry and clear weather is expected tonight. Patchy fog is possible in some valley locations late tonight, mainly near bodies of water. && .SHORT TERM... (Saturday through Sunday night) Issued at 100 PM CDT Fri Sep 20 2024 The 5h ridge and 8h high looks to stay in about the same place Saturday into Sunday as a shortwave/upper low ejects from the Four Corners region into the central Plains. This will keep innocuous weather going in our area through the weekend. There will be a weak shortwave dropping southeast through the 5h ridge position Saturday night which may bring mid and high clouds through TN into north AL. Will keep the suggested 5-10% PoP in far north AL and southern middle TN on Sunday, but looks like vast majority will stay dry. Temperatures will be fairly persistent as well, with highs in the upper 80s to lower 90s and lows in the middle 60s to around 70. && .LONG TERM... (Monday through Thursday) Issued at 429 AM CDT Fri Sep 20 2024 Extended range guidance from the most recent suite of global models suggests that an upper low (initially across the MO Valley) will open into a trough as it shifts northeastward into the Lower Great Lakes by Tuesday. The surface frontal wave will move in conjunction with the trough, with a trailing cold front predicted to enter the region at some point Tuesday afternoon. Thus, although POPs will remain fairly low across the area on Monday, we do anticipate a general increase in the spatial coverage of showers and thunderstorms beginning in the northwest early Tuesday morning and continuing for the entire region during the day. Although forecast soundings depict a general increase in instability during this timeframe (due to higher surface dewpoints), profiles will remain dry aloft, and for this reason we will keep rain chances in the low-medium (20-30%) chance range. Forecast uncertainty increases considerably by Wednesday and Thursday, as the global models offer vastly differing solutions regarding how far south/east the cold front will track before stalling in response to the development of a cutoff upper low over the Mid-MS Valley. If a deeper cool/dry airmass manages to penetrate through the entire CWFA, then we will remain in a dry weather pattern during the mid-week period. However, current thinking is that the front will stall in our region (or perhaps to our immediate south/east), which could support the development of widespread anafrontal precipitation across our region. We have indicated a low POP to account for this level of uncertainty, but these values will likely be adjusted over the coming days. Temps will also be impacted by the ultimate outcome of the forecast, but at this point we have indicated highs falling back into the l-m 80s. && .AVIATION... (18Z TAFS) Issued at 1214 PM CDT Fri Sep 20 2024 VFR flight weather conditions are forecast through this evening. Patchy BR with visibility of 3-5SM (MVFR) is expected from 09-13Z. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...17 SHORT TERM....17 LONG TERM....70 AVIATION...17