Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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966 FXUS64 KHUN 012341 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 641 PM CDT Mon Jul 1 2024 ...New AVIATION... .NEAR TERM... (Remainder of today and tonight) Issued at 224 PM CDT Mon Jul 1 2024 Light NNW flow aloft will persist across the TN Valley for the remainder of the day, to the east of a strong subtropical ridge centered across northeastern TX. At the surface, gusty NNE winds will continue to advect a drier boundary layer airmass into the region through sunset, due to a contracted pressure gradient between a high over the Great Lakes and a developing frontal wave across southern GA/northern FL. Highs appear on track to reach the u80s-l90s. Current thinking is that dewpoints will continue to slowly fall into the mid 50s this evening, which should allow for several hours of accelerated cooling (and potential development of patchy fog near large bodies of water) as northeasterly winds subside and skies remain mostly clear. Shortly after Midnight, surface winds will begin to veer to SE as the frontal wave to our south retrogrades along the central Gulf Coast and the ridge to our northeast expands southwestward in the lee of the Appalachians. This will quickly begin to advect low- level moisture (and some stratus clouds) northwestward into the region, with lows ranging from the mid 60s (NW) to u60s-l70s (SE). && .SHORT TERM... (Tuesday through Wednesday night) Issued at 224 PM CDT Mon Jul 1 2024 Latest model consensus suggests that the center of the strong subtropical ridge (noted above) will build slowly eastward Tuesday/Tuesday night, becoming centered across the Gulf Coast states of MS-AL-GA on Wednesday/Wednesday night. In the lower levels, SSE flow will gradually strengthen Tuesday and Tuesday night as the center of the surface ridge (noted above) translates eastward and offshore the northern Mid-Atlantic coast. Dewpoints will climb back into the 65-70F range for most of the CWFA (perhaps a bit higher in the west and a bit lower in the east, where impacts from the dry continental airmass will linger), resulting in heat index readings in the 100-105F range from Lincoln-Madison-Marshall counties westward as afternoon highs return to the l-m 90s. During the Wednesday-Wednesday night timeframe, a surface cold front related to a northern stream mid-level trough lifting east- northeastward into Ontario/Quebec will drift into the OH Valley before stalling. This will occur as a low-level ridge axis becomes established along the central Gulf Coast, resulting in lighter SSW winds across our region. Dewpoints will slowly increase into the l-m 70s for the entire region in this regime, which (coupled with a minor increase in highs on Wednesday) should achieve Heat Advisory criteria for the same portion of the CWFA mentioned in the paragraph above. Strong heating of the increasingly moist boundary layer may also generate a few showers/thunderstorms on Wednesday afternoon/evening, but due to the position of the subtropical ridge across our region we have only included a low (15-20%) chance POP in the grids. && .LONG TERM... (Thursday through Sunday) Issued at 209 AM CDT Mon Jul 1 2024 An upper ridge will continue to maintain its hold over the southeastern states to start the long term. However, a shortwave trough moving over the north-central CONUS and Midwest will cause the ridge to flatten over the Tennessee Valley on Friday. This impulse will quickly progress to the northeast into Canada on Saturday; but, the parent trough will persist over the central portion of the country through the weekend as the aforementioned ridge is pushed over the Deep South and off over the Atlantic. The surface pattern will largely mirror the upper level pattern, as surface high pressure over the Southeast is shunted south and eastward as a cold front moves over the Mississippi Valley on Friday. This front looks to slowly make its way towards the Tennessee Valley by early Saturday, then stall over the region and weaken by Sunday. For sensible weather, expect daily chances of showers and storms increasing through Friday where medium to high chances (50-70%) are forecast. Medium chances (40-50%) continue on Saturday, then decrease to low (20-30%) by Sunday as the surface front weakens over the region. While models show ample instability through the weekend, shear is fairly meager on Thursday and Friday. Therefore, anticipating the usual summertime thunderstorms that may produce brief, heavy downpours, lightning, and some gusty winds. Although, some guidance indicates that shear values increase to between 20-25 knots or so on Saturday. This would suggest that some stronger storms may be possible on Saturday. However, we will continue to monitor these trends over the next few days. The other concern for the long term period will be the heat, particularly on Thursday (Independence Day holiday) and Friday. High temperatures these days are forecast to reach the lower to mid 90s. Dew points are also expected to be in the lower to mid 70s during the day, with lows Wednesday, Thursday, and Friday nights in the lower to mid 70s. This will result a major risk of heat for much of the local area both Thursday and Friday (according the the NWS HeatRisk tool). Just strictly looking at heat indices, we`re looking at generally between 100-109 degrees both days as well. These will be the days to watch for any potential heat products, but please remember heat safety this 4th of July holiday! Take frequent breaks in the shade, wear loose- fitting and light-colored clothing, and stay hydrated! A very slightly cooler weekend will then follow as highs top out in the lower 90s with lows Saturday night in the lower 70s. && .AVIATION... (00Z TAFS) Issued at 641 PM CDT Mon Jul 1 2024 VFR conditions will continue through the TAF period at both terminals as winds veer from the north to the southeast. Gradient flow will increase tomorrow resulting in sustained winds near 10kts with gusts up to 15kts. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...70 SHORT TERM....70 LONG TERM....26 AVIATION...25