257 FXUS64 KBMX 090525 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 1225 AM CDT Mon Sep 9 2019 .UPDATE... For 06Z Aviation. && .SHORT TERM... /Updated at 0919 PM CDT Sun Sep 08 2019/ Although model output has a range in surface dew points Monday, it appears that the moisture increases just above the surface. Surface dew points should be in the 69-72 range in the southeast as the temperatures rise into the mid and upper 90s. Therefore, there is a short window where heat indices reach or exceed the 105 degree mark. Went ahead and extended the Heat Advisory into Monday evening. The only change being removing a few of the western counties where heat indices are in the 100-105 range. Otherwise, overnight temperatures will drop into the 60s and 70s with little cloud cover. Some brief fog or low clouds may develop in far southern areas toward sunrise, but it appears limited in time and space. 75 Previous short-term discussion: /Updated at 0246 PM CDT Sun Sep 08 2019/ Through Tonight. The weak front has stalled across southern portions of the forecast area this afternoon. With dewpoints in the low 70s near and south of the front, heat indices at or above 105F remain possible this afternoon. Also, cannot rule out a shower or storm near the front. Looking ahead to tomorrow afternoon, more rain and cloud coverage is expected across the south as the stalled front moves northward. Currently, forecasted heat indices are near or at criteria for the extreme southeastern counties, but convective timing and coverage tomorrow will play a big part in whether advisory conditions are met. Will continue to highlight heat in the HWO and hold off on another advisory for now. 14 .LONG TERM... /Updated at 0350 AM CDT Sun Sep 08 2019/ Monday through Saturday. The upper-level ridge will center over Georgia and South Carolina on Monday as a mid-level shortwave trough moves northward through Texas. Winds will gradually shift from northerly to southerly/southeasterly and advect the weak surface front back northward as a warm front. This will allow for isolated to scattered thunderstorm development south of the moisture gradient, mainly along and south of I-85 then spreading northward through the day, where the most favorable environment for development will exist. Once again, not expecting a lot of coverage since high pressure will dominate on the synoptic scale, so thunderstorms will need to overcome subsidence and dry mid- level air to become sustainable, but higher low-level moisture content will remain and potentially increase across the south, especially with the return of southerly flow. Hot afternoon temperatures continue on Monday which will allow for moderate destabilization during the afternoon with inverted-v signatures noted on forecast soundings below 850mb and dry mid-level air aloft. The environment will support an isolated microburst risk, but only if storms are able to overcome the aforementioned factors to develop. Additionally, dewpoints south of the front will remain in the low 70s, and counties near the I-85 corridor and south may require a Heat Advisory again on Monday as the front moves northward and temperatures hit the upper 90s. Therefore, I will keep heat in the HWO for Monday with an increased confidence. While temperatures will still be above average for locations north of I-85, these areas will be north of the front and dewpoints should mix into the low 60s. Most areas will remain dry Tuesday through Friday thanks to the high pressure building over the Southeast and only a few isolated to scattered afternoon showers and storms will be possible through this period. Highs will remain above average until finally beginning to trend downward on Saturday when the upper level ridge flattens over the region and begins building over the western Atlantic. Guidance is in fairly good agreement on rain chances increasing late Saturday as an inverted trough of low pressure moves westward across the Gulf Coast and cyclonic flow aloft increases over the forecast area. 86 && .AVIATION... 06Z TAF Discussion. With light winds and a better moisture profile, will continue with some MVFR fog at MGM and TOI on either side of sunrise. Meanwhile, a frontal boundary moves northward today and winds will begin to shift to a more southerly direction by the afternoon. These winds will be 5-10kts. A few showers/thunderstorms may develop near the boundary and deeper moisture and advertised a PROB30 at MGM/TOI at this time after 21z. Otherwise, VFR conditions. 16 && .FIRE WEATHER... A slight increase in moisture is expected for the first half of the work week, with minimum RH values in the upper 30s and 40s each afternoon through Wednesday. Isolated to scattered rain chances expected each afternoon for portions of the area, but most locations will remain dry. 20ft winds will be from the south to southeast each day, below 6 kts. KBDI values will remain elevated due to ongoing drought conditions. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 97 70 95 70 95 / 10 10 30 20 20 Anniston 98 71 95 70 95 / 20 10 30 20 20 Birmingham 98 73 95 73 96 / 10 10 20 10 20 Tuscaloosa 97 73 94 73 96 / 20 10 10 10 10 Calera 98 71 94 71 95 / 20 10 20 10 10 Auburn 95 72 93 71 93 / 20 20 30 10 10 Montgomery 98 73 96 73 96 / 30 20 20 10 10 Troy 96 71 94 70 95 / 40 20 20 10 10 && .BMX WATCHES/WARNINGS/ADVISORIES/... Heat Advisory until 9 PM CDT this evening for the following counties: Autauga...Barbour...Bullock...Dallas...Elmore... Lowndes...Macon...Montgomery...Pike...Russell. && $$