Area Forecast Discussion
Issued by NWS Birmingham, AL
Issued by NWS Birmingham, AL
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785 FXUS64 KBMX 270851 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 351 AM CDT Thu Jun 27 2024 ...New LONG TERM... .SHORT TERM... (Tonight through Friday) Issued at 835 PM CDT WED JUN 26 2024 Well, a tricky forecast this afternoon and evening. Temperatures were quite hot again with a few places into the low 100s while most others were in the 90s. Thunderstorms did initiate in western Alabama with heating of the day and an approaching upper trough. Outflows from activity in Mississippi also aided in storm development. A few of these storms produced severe wind gusts over 60 mph and blowing trees down. Much drier and more stable air was over eastern Alabama, but the storms held on and many places did get rain and thunderstorms east. No additional severe weather is anticipated overnight, but more showers and storms are possible. A fine line of activity was indicated near Memphis this evening. This was near a surface cold front and a trough aloft. These features will swing into the area overnight and Thursday. Will continue the belief that there is an increased signal that the entire system will be slower to exit. This leads to better rain chances than initially thought. Lows will be near 70 overnight and highs 85 to 95 on Thursday. 75 Previous short-term discussion: (This afternoon through Thursday) Issued at 111 PM CDT WED JUN 26 2024 Contrary to much of the 12Z guidance, a large coverage of showers and thunderstorms have already developed across much of central and eastern Mississippi and into western portions of central Alabama. Once the cu field began developing this morning, it didn`t take long for rain to start falling. This activity is being driven by a large increase in moisture associated with an approaching trough axis and cold front over the Mid-south region. There`s currently a moisture gradient over the area, and there`s still some drier air across the eastern half where dewpoints have once again mixed down into the lower to mid 60s. However, moisture will advect eastward with propagation of the trough, so expect further area-wide development of convection through the afternoon with the highest chance for rain focused generally along and west of I-65. This rain should give us some relief from the heat, but not soon enough as most areas have already reached the mid to upper 90s. Per RAP mesoanalysis, MUCAPE is around 3000-4000 J/kg in our west where dewpoints are in the lower 70s. While shear values are rather weak, some strong downbursts may produce damaging winds, and storms could also produce torrential downpours with PWATs around 2". There`s been an increasing signal of scattered showers and storms continuing overnight and into tomorrow as the cold front and strong PVA move southward into the area. Some hi-res models are even resolving an MCV-like feature over the area early tomorrow morning which would further support additional rain and thunderstorms. So luckily, the odds at receiving beneficial rain seem to be improving for the next 24 hours. The scattered to numerous showers and cloudy skies will keep temperatures in the 80s tomorrow. 86/Martin && .LONG TERM... (Friday night through next Wednesday) Issued at 332 AM CDT THU JUN 27 2024 Key message: - Oppressively hot and humid conditions are expected this weekend, with dangerous heat possible on Sunday as heat indices rise above 105 degrees. A multi-day heat wave is expected to continue through much of next week. Best rain chances will exist Saturday through Sunday, with scattered showers and storms possible each afternoon through the end of the forecast period. Another prolonged period of oppressive heat will begin this weekend as the 500mb ridge begins to build and broaden from Texas all the way east through the Deep South. The big difference in this heat wave compared to the one we`ve recently experienced will be the addition of more tropical low-level moisture with dewpoints expected to remain in the 70s during the afternoon hours. Rain chances on Saturday will remain across the eastern and southeastern portions of Central Alabama, with higher PWATs and deeper 700mb moisture transport from the southwest. Although shower and storm coverage is expected to be scattered to numerous, temperatures aloft due to the 500mb ridge strengthening to 597 decameters will be quite warm. Therefore strong to severe storms are not expected at this time. Where it doesn`t happen to rain, heat indices will rise between 100 and 105 degrees Saturday afternoon as highs top out in the low to mid 90s. So, even though we may escape Saturday without issuing a Heat Advisory, all bets will be off on Sunday. As the ridge continues to strengthen but slightly retrograde off to our west, a shortwave trough is expected to move through the Great Lakes states Sunday morning. A cold front will be moving southward into northern Arkansas and Tennessee during that time, along with synoptic lift in the form of a 500mb vort max within the northwesterly flow. Convective development will be likely with strong surface instability as temperatures rise into the mid to upper 90s with dewpoints holding in the low to mid 70s. A Heat Advisory will be needed if current guidance trends hold, but widespread convective development (potentially in the form of an MCS) may throw a wrench in those trends if storms move through a bit earlier. As of now, heat indices Sunday afternoon should easily rise between 105 and 110 degrees for just about everyone. The cold front is currently progged to move southward on Monday, with a fresh fetch of dry air moving in from the north at 700mb. How far south the dry air at the surface can move southward is still in question, which will affect locations that may need another Heat Advisory Monday afternoon. For now, those locations appear to be along the U.S. 80/I-85 corridors and points southward with plenty of moisture pooling out ahead of the surface front. Scattered to numerous showers and storms can also be expected across the southern half of Central Alabama. The 500mb ridge is currently advertised to build back in over Deep South through Thursday, with isolated to scattered showers and storms possible during the peak heating of the day. As highs top out in the upper 90s each day, we could enter into a prolonged period where Heat Advisories may be needed for several days in a row. With this being said, we`ll also have to start keeping an eye on the dreaded Drought Monitor, with significant rain chances staying out of reach likely through the end of next week. 56/GDG && .AVIATION... (06Z TAFS) Issued at 120 AM CDT THU JUN 27 2024 All sites are currently VFR. MVFR cigs will spread across most of C AL from the NW after 9z lasting through midday as a surface low inches SE into the state. There will be chances for SHRA and TSRA across the area at times as the low drags a frontal boundary toward the I20 corridor by sunset and a little further SE toward the I85 corridor tonight/Thu night. Overall winds should be light outside of convection. Some reduced vsbys may occur briefly with heavier convection. 08 && .FIRE WEATHER... Scattered to numerous showers and storms can be expected today across much of Central Alabama, but widespread wetting rains are not expected. Min RH values this afternoon will be much higher than previous days, in the 55 to 65 percent range. Transport winds will remain light and variable at times through the afternoon today. Fortunately, we`re not expecting much in the way of gusty erratic winds with showers and storms today like what was observed on Wednesday. Scattered showers and storms will remain in the forecast for Friday, confined more to the southern half of Central Alabama. Transport winds are expected to increase out of the southwest between 10 and 15mph by Friday afternoon. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 88 69 92 72 / 50 20 50 20 Anniston 89 72 91 74 / 60 20 50 20 Birmingham 89 73 93 75 / 60 20 40 20 Tuscaloosa 88 72 92 75 / 60 20 40 10 Calera 89 73 93 75 / 60 20 50 20 Auburn 89 73 90 74 / 70 40 60 20 Montgomery 90 73 92 74 / 70 40 60 20 Troy 89 71 92 73 / 70 40 70 20 && .BMX WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...75 LONG TERM....56/GDG AVIATION...08