Area Forecast Discussion (AFD)
Issued by Huntsville, AL (HUN)
820 FXUS64 KHUN 182324 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 624 PM CDT Tue Sep 18 2018 .UPDATE... For 00Z TAFS. && .NEAR TERM...(Tonight) Issued at 351 PM CDT Tue Sep 18 2018 For the latter half of September, it is undoubtedly very warm to hot outdoors, with mid afternoon temperatures rising into the upper 80s to mid 90s. "Normal" highs this time of year are around 84 - both in Muscle Shoals and Huntsville. The remnants of TD Florence was finally moving off of the northern Mid Atlantic coast, thanks to broad high pressure extending southward from Ontario to the Ohio Valley. Despite the former TD moving off of the coast, looks like it could try to make some sort of a comeback very late in the forecast period - more on that later. At the moment, isolated showers were in progress across parts of the Tennessee Valley, moving southward at 10-15 mph. This activity for the most part has been lightning free so far. Deeper moisture and higher instability values to our south has resulted in more organized storms closer to the Gulf coast. Showers that form will provide a little relief from the heat, but will add additional moisture to areas affected. This could come in to play later tonight, as more patchy fog is expected. Added areas of fog, with greater coverage of fog in and close the river valleys. As was the case last night, a few spots could be affected by locally dense fog with visibilities reduced to 1/4 of a mile or less in spots. Warm conditions for late Sept tonight, with low temperatures cooling in the mid 60s to around 70. Normal lows this time of year are in the lower 60s. .SHORT TERM...(Wednesday through Thursday) Issued at 351 PM CDT Tue Sep 18 2018 A foggy start is possible around daybreak Monday, otherwise a near repeat performance temperature wise is expected. Drier air filtering in from the west and more subsidence will make for a dry day across the Tennessee Valley. High temperatures should rise into the lower 90s. Given recent trends with highs now nearing the mid 90s, they may need to be boosted into the mid 90s. Previous record highs of 99 in Muscle Shoals and 101 in Huntsville should survive. Similar conditions are expected on Thursday, with highs rising into the lower 90s once again. Light northeast to east winds on Wednesday, should become southeasterly during Thursday, as the surface ridge exits the New England/Mid Atlantic coast. .LONG TERM...(Thursday night through Monday) Issued at 351 PM CDT Tue Sep 18 2018 The return southerly flow will bring greater amounts of moisture from a very warm Gulf of Mexico (average water temperatures in the mid 80s). This moisture, along with lift and instability will bring isolated to scattered showers and thunderstorms to the forecast beginning on Friday. Stayed on a diurnal trend into Sunday night, with higher rain chances in the daytime and lower at night. An upper low currently near Bermuda will in part absorb a portion of TD Florence as it moves out to sea. But it should begin returning to the west as it rounds the eastern half of the Bermuda high and heads westward during the weekend and early next week. However, it will return only as an unorganized area of deeper moisture in the trade flow, across the Bahamas and further SE CONUS early next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 624 PM CDT Tue Sep 18 2018 VFR conditions are expected at the KMSL and KHSV terminals through the first 6 to 9 hours of the forecast period. Winds will be light and variable through most of the night, and become calm by 09Z. Given the calm winds and moisture in place, MVFR fog may develop after 09Z at each terminal. While confidence is very low, have maintained a reduction in visibility, though thinking visibilities will remain at or above 4SM. Any fog that does develop will lift by 14Z, leaving VFR conditions through the remainder of the period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...RSB LONG TERM...RSB AVIATION...73 For more information please visit our website at weather.gov/huntsville.