Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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474 FXUS64 KHUN 040755 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 255 AM CDT Thu Jul 4 2024 ...New NEAR TERM, SHORT TERM, LONG TERM... .NEAR TERM... (Today) Issued at 254 AM CDT Thu Jul 4 2024 Dangerous heat continues this Independence Day as a strong area of high pressure just to the southeast of the Tennessee Valley will continue to support ample sunshine and a warm/humid air mass. Today may end up being the warmest day of the week so far, especially in our eastern zones -- with forecast highs in the mid 90s nearly everywhere (and portions of north central and northwest Alabama reaching the upper 90s). These hot temperatures, combined with deep moisture (dewpoints in the mid 70s) will produce dangerous heat index values between 105-109 degrees over a vast majority of the area. Additionally, urbanized areas (Florence, Decatur, and Huntsville) may briefly see heat index values exceed 110 degrees due to heat island impacts from localized higher temperatures. The threat for heat related illnesses, especially if you have outdoor plans this 4th of July holiday, cannot be understated. Please exercise extra caution and check on those in our community who are particularly vulnerable to heat. A Heat Advisory remains in effect areawide. Sufficient moisture underneath the ridge may allow for some low chances for diurnally driven showers/storms (25-40%) during the afternoon/evening hours. These storms will be disorganized and short-lived due to the extremely weak shear profile. Latest guidance is trending down with PoPs (likely due to subsidence from the ridge), so still think that most locations will remain dry. However, given the amount of outdoor activities this holiday, be prepared to move indoors if you hear thunder or see a flash of lightning. && .SHORT TERM... (Tonight through Saturday Night) Issued at 254 AM CDT Thu Jul 4 2024 The Heat Advisory continues overnight due to the very limited relief from the heat as low temperatures will again range between 75 to 80 degrees in most locations. A mid/upper trough will pivot from the northern Plains into the Great Lakes late tonight into Friday. Hi-Res guidance shows an MCS developing along this boundary well to our north and west this evening over the Ozarks and drifting toward the Mid South vicinity by early Friday morning. This activity will likely weaken considerably as its remnants move into the Tennessee mid/late Friday morning, but it will still bring some low to medium chances for showers and storms along with higher cloud cover. Additional convection will likely redevelop later in the afternoon/evening along this remnant boundary, where coverage is forecast to be much higher (80-100%). Depending on how much destabilization can occur, a few of these storms may become locally strong with gusty winds and heavy downpours being the threats. These clouds and high rain chances will be the "wild card" with respect to heat impacts on Friday. Given highs still progged to reach the mid 90s and peak heat indices still forecast to exceed or come close to 105 degrees, will maintain the Heat Advisory through 7 PM Friday. Should more heating become apparent and/or rain chances lessen, another solid day of widespread dangerous heat will likely evolve in this hot/humid air mass. The frontal boundary will push south and east into central Alabama Friday night into Saturday. However, with this boundary still in our vicinity low chances for showers/storms will remain in the forecast for Saturday. A slightly cooler/drier air mass will help to keep the dangerous heat at bay, however. Highs in the upper 80s to lower 90s will be common -- with peak heat index values remaining below 100 degrees. && .LONG TERM... (Sunday through Wednesday) Issued at 254 AM CDT Thu Jul 4 2024 On Sunday, upper level ridging looks to be stretched over the Atlantic and down through the Deep South. A large upper trough will dominate the central CONUS but also extend up into the Ohio Valley and Canada. This leaves the local area in southwesterly flow aloft, and this will continue through at least Monday night until the trough finally starts to swing to the east/northeast on Tuesday and Wednesday. The surface front that is slated to move south of the area on Saturday is expected to meander over this region through early next week. Another cold front is then anticipated to progress over the Ohio Valley by midweek. For sensible weather, after a dry day on Sunday, daily chances (generally low to medium, 30-60%) of showers and storms are forecast through midweek. This is especially true during peak heating (afternoon hours). Sufficient instability for thunderstorm development is anticipated, along with shear around 20 knots. While severe weather is not expected at this time, heavy downpours, lightning, and some gusty winds will all be possible in any thunderstorms that do develop. Additionally, the chances of showers/storms and amount of cloud cover will cause temperatures to be slightly cooler than we`ve seen this week, with values in the lower to mid 90s Sunday and Monday and upper 80s to lower 90s Tuesday and Wednesday. Expecting lows to mainly be in the upper 60s lower 70s each night. Even though the forecast calls for a bit cooler conditions, it will still be warm (especially early next week). Please continue to be cautious if you have outdoor plans. Take breaks in the shade and stay hydrated! && .AVIATION... (06Z TAFS) Issued at 1255 AM CDT Thu Jul 4 2024 VFR conditions will be the predominant flight category at each terminal through the period. Low chances for TSRA/SHRA are forecast this afternoon, but given low confidence in coverage have kept a mention of them out of the TAF at this time. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Heat Advisory until 7 PM CDT Friday for ALZ001>010-016. TN...Heat Advisory until 7 PM CDT Friday for TNZ076-096-097. && $$ NEAR TERM...AMP.24 SHORT TERM....AMP.24 LONG TERM....26 AVIATION...AMP