547 FXUS64 KBMX 072007 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 307 PM CDT Tue May 7 2019 .SHORT TERM... Through early Thursday. Surface high pressure nosing into the southeast states from the east coast will hold on for one more day, helping to keep most/all of central free from rain through Wednesday. As the high breaks down, and the next system starts to approach from the west, south to southeast low level winds do start to kick in by Wednesday afternoon. The added gulf and atlantic moisture could help set off a couple showers or storms. But I think any coverage would be less than 15 percent, and have opted to leave the mention of precip out of the forecast for Wednesday for now. Significant changes to our weather pattern start Wednesday night into Thursday, as a series of upper level shortwave troughs moving through the lower MS valley help break down the upper level ridge that has provided us with our recent dry spell. Showers and storms are expected to become increasingly likely for our area by late Thursday, as a cold front associated with the aforementioned upper troughs presses closer to Alabama. /61/ .LONG TERM... /Issued at 300 AM CT/ Thursday afternoon through Tuesday. The main trough doesn't make much eastward motion, so the ridge to our east helps keep any shortwave impulses to our north and west through at least Thursday afternoon. By then, a pre-frontal shortwave will slide into Central AL, leading to increased thunderstorm chances, especially north and west of the I-59 corridor. Instability is expected to be 1000-2000 J/kg and some model guidance suggests downdraft CAPE could approach 1000 J/kg, so its feasible that some of the storms Thursday afternoon in the far northwestern counties could become strong to severe. However, 0-6km bulk shear is 25-35kts, which doesn't really promote sustained updrafts. In addition, model guidance is split on timing and coverage of storms associated with this shortwave, so I'm going to hold off adding in mention for severe weather in the HWO at this time. The cold front finally catches up, and slowly approaches our area Friday into Saturday. This will lead to continued thunderstorm chances for most of Central AL as the frontal boundary becomes diffuse and stalls out across the state. At least two more shortwave impulses move through the trough to our west and slide through Central AL over the weekend. Unfortunately, this means rain and thunderstorms will persist along the stalled frontal boundary through Sunday. On Monday, an upper level low moving through the Great Lakes region pushes a dry cold front southward into the Gulf States. This cold front has a little more forcing to it, so it is able to push the stalled boundary south of our area, finally decreasing rain chances for Central AL Monday afternoon through Wednesday. The slightly cooler air mass behind the front will lead to more seasonable diurnal temperatures for the first half of next week. 25/Owen && .AVIATION... 18Z TAF Discussion. High pressure will provide at least another 24 hours of mostly clear weather across central Alabama terminals. As overnight temperatures creep up each night, temperature difference between air and bodies of water will be less, so that fog formation is less likely. Will maintain VFR forecast across all TAF sites this forecast cycle. /61/ && .FIRE WEATHER... Drier weather will continue through Wednesday with temperatures in the mid to upper 80s. An approaching storm system will bring enhanced rain chances starting late Thursday, and lasting through much of the weekend. There are no fire weather concerns at this time. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 60 88 65 84 67 / 0 10 10 50 70 Anniston 62 87 66 84 67 / 0 10 10 40 60 Birmingham 64 89 68 85 68 / 0 0 10 60 70 Tuscaloosa 62 89 68 85 68 / 0 0 10 80 70 Calera 62 88 67 84 67 / 0 10 10 50 60 Auburn 63 86 66 84 68 / 0 10 10 30 30 Montgomery 62 89 67 88 69 / 0 10 10 40 40 Troy 62 88 66 86 68 / 0 10 10 30 20 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$