Area Forecast Discussion
Issued by NWS Birmingham, AL
Issued by NWS Birmingham, AL
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345 FXUS64 KBMX 290533 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 1233 AM CDT Sat Jun 29 2024 ...New AVIATION... .SHORT TERM... (Tonight through Sunday) Issued at 817 PM CDT FRI JUN 28 2024 We`ve got clusters of showers of all shapes and sizes this evening; one small, one medium, and one large. While the expected trend if for a decrease in coverage through the next few hours, there`s bound to be some precipitation still around come midnight or so. Looks like the best rain chances through 06Z will be straddling and following I-85 from southwest to northeast. Overnight, places that get the evening showers are the prime locations for fog formation. Stratus development last night was pretty much across the whole CWA, and no reason to think tonight will be any different. After accounting for areas that cooled early due to rain, temperatures trends are pretty much on track. /61/ Previous short-term discussion: (This evening through Saturday) Issued at 1237 PM CDT FRI JUN 28 2024 High pressure aloft will build into the state from the west today through Saturday. Low and mid level flow will remain from the south and the southwest with plenty of moisture advecting into the state. Diurnal convection will be expected each day, with development of isolated showers beginning by midmorning and thunderstorms expected through the afternoon. Instabilities will be on average between 2000 and 2500 J/kg each day. Shear is fairly weak, though a few pockets of 20 kts is possible each afternoon. PW values will be max this time of year climatologically. With all this said, could expected a few storms to be strong, though severe storms should be limited. A few slow moving or training storms could cause localized flooding due to the high rainfall rates expected. Temperatures today will be in the lower 90s with lows tonight in the low to mid 70s. Fog development is possible in a few areas through the early morning, though with the winds expected to be light and cloud cover to continue overnight, fog may be more patchy in nature. Saturday afternoon, a few areas may reach heat indices around 105, especially in the northwest where shower and thunderstorm development is expected to be more isolated until later in the afternoon. Areas in the south may actually stay around 100 degrees or slightly lower due to increase in cloud cover and activity. May need a heat advisory, but but will continue to assess. 24 && .LONG TERM... (Saturday night through next Thursday) Issued at 236 PM CDT FRI JUN 28 2024 Not much change in the long term forecast this afternoon, unfortunately. Although rain chances remain elevated given the presence of an upper level shortwave and front, low level moisture is high as well. And that will push heat indices into the 104-109F range for most of the area Sunday afternoon. After a reprieve on Monday and Tuesday, upper level ridging will build back into the area and moisture to increase. Heat indices will be back in the 104-107F range for the end of the week. 14 Previous long-term discussion: (Saturday night through next Thursday) Issued at 333 AM CDT FRI JUN 28 2024 Key messages: - Dangerous heat remains in the forecast for Sunday, dependent upon daytime heating occurring before showers and storms develop/arrive Sunday afternoon and evening. Heat indices between 105 and 110 degrees are currently forecast, and a Heat Advisory will likely be needed. Highest rain chances will also exist Sunday afternoon through Sunday evening as a cold front approaches from the north. - A multi-day heat wave is still anticipated through much of next week, starting Tuesday and lasting through at least the end of the week. Heat indices are forecast at or above 105 degrees in many locations next Wednesday through Friday. The 500mb ridge over Texas will continue to strengthen to 598 decameters, but retrograde slightly to the west on Sunday. This will place Central Alabama within almost northerly flow aloft. The upper level shortwave trough moving through the Great Lakes states appears to be a bit more potent on guidance this morning, which will help to push the surface cold front well into the Deep South. As the front approaches, we`ll see low level moisture pooling out ahead of the front with high PWATs in combination with strong surface heating. As a result, dangerous heat will remain in the forecast with temperatures rising into the low to mid 90s between 11am and 2pm. Heat indices could rise between 105 and 110 degrees as dewpoints stay in the low to mid 70s. A Heat Advisory will be needed if current forecast trends hold up. With the surface front approaching from the north and a weak 500mb vort max moving in from the northwest, scattered to numerous showers and storms are expected to develop Sunday afternoon through Sunday evening. We`ll have to see how soon some of the convection is allowed to develop, as it may temper high temps a bit. In addition, a more organized convective cluster of storms may develop and dive southward through the day. We can certainly hope that coverage of showers and storms will be fairly widespread on Sunday to help with the dry conditions, as significant rain chances aren`t expected through much of next week with heat building once again. Model consensus is in good agreement with the cold front moving at least as far south as the U.S. 80/I-85 corridors by Monday afternoon, and potentially farther south than that. Drier air is expected to advect southward both at the surface and aloft, giving us a temporary reprieve from the worst heat indices. We still could hit Heat Advisory criteria in our far southern counties with scattered showers and storms developing south of the front. The 500mb ridge will build in across the Southeast through Thursday, keeping high temperatures in the mid to upper 90s each day. Isolated to scattered showers and storms will be possible during the peak heating of the day mainly in the east and southeast on Tuesday. As southeasterly to southerly low level flow picks back up on Wednesday, scattered convection is expected areawide during the peak heating of the day through the end of the week. 56/GDG && .AVIATION... (06Z TAFS) Issued at 1228 AM CDT SAT JUN 29 2024 Overnight, ceiling and visibility forecast will be based on persistence and heavier rain locations from Friday. This will place the lowest ceilings, and lowest visibility, at EET and MGM. It appears now based on trends that most if not all sites will drop to IFR ceilings by daybreak. Any stratus and fog that does form overnight should lift and mix out by around 15Z. Rinse and repeat in the afternoon, with more scattered to numerous convection in the heat of the afternoon and into the early evening. 16 && .FIRE WEATHER... Rain chances increase for Saturday and Sunday, as minimum RH values remain in the 50 to 60 percent range both afternoons. Southwesterly 20ft winds Saturday become northwesterly Sunday, but remaining light between 5 and 10mph overall. Drier conditions and less humidity is expected Monday and Tuesday. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 91 71 96 70 / 70 30 70 20 Anniston 90 74 93 73 / 70 30 70 20 Birmingham 91 75 96 74 / 70 30 70 20 Tuscaloosa 92 75 96 73 / 70 50 70 30 Calera 92 76 95 75 / 70 40 70 30 Auburn 89 75 92 74 / 70 30 70 30 Montgomery 91 74 94 74 / 70 30 70 30 Troy 90 73 93 73 / 70 30 70 40 && .BMX WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM.../61/ LONG TERM....14 AVIATION...16