066 FXUS64 KBMX 051142 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 642 AM CDT Wed Jun 5 2019 .UPDATE... For 12Z Aviation. && .SHORT TERM... Today and Tonight. A few lingering rain showers persist across our northern counties this AM despite drier air and subsidence. Partly cloudy skies can be expected for much of the area this morning with only a slight chance of a shower. The air mass over our area is still too dry to support the development of thunderstorms this morning. Upper level impulses ahead of an upper level trough and low pressure system will continue to break down the ridging pattern currently over much of the Southeast. Similarly, the axis of 2" precipitable water will continue to progress towards Alabama and will further aid in the increase of moisture into our area. In response, cloudiness and rain chances will increase from west to east throughout the day. A slight chance of a thunderstorm cannot be ruled out but any activity will be scattered in nature. High temperatures will range from the upper 80's to low 90's with lows in the upper 60's to low 70's. 07 .LONG TERM... /Issued at 330 AM CT/ Thursday through Wednesday. Rain chances increase substantially across Central AL beginning Thursday and continuing through the first half of next week. An upper level low slowly pushes through the Great Plains Thursday, and a few shortwaves eject from the base of that trough Thursday into Friday. This will produce enough lift for nearly widespread showers across the area, though I think some breaks will occur based on exact timings of the impulses. There will be some instability work into the area, but values aren't too high(only 300-800 J/Kg). Therefore, I've kept most of the forecast as rain with the chance for thunderstorms both Thursday and Friday afternoons. The source region for the moisture with this system is coming from a very weak tropical disturbance off the Southern TX coast. This could lead to some fairly heavy rainfall at times, but given we've seen many days without rain across the area, the river and creeks should be able to withstand the initial rain amounts. The upper level low really isn't in a hurry to go anywhere as we go into the weekend. As it gets closer to our area Saturday and moves overhead on Sunday, expect much more lifting with the synoptic height falls. The low will also lead to cooling aloft, which will lead to an increase in instability across the region making thunderstorms more likely. Shear remains very low, limiting any significant severe potential, though the tropical air mass will allow for some very efficient rain-producing storms. PWATs are forecast to be at or just over 2.00", which is near the maximum in climatology for this time of year. Therefore, I can't rule out the possibility of isolated flooding concerns, especially if any convective storms become more stationary or train over one another. At this time, however, confidence is too low to add mention in the HWO for flooding. Latest guidance suggests the slow-moving upper level low will drift eastward into Georgia late Monday night into Tuesday. I've trended PoPs down in the eastern counties Monday night to reflect this, though the exact timing of the upper low's departure may still change given this remains 6-7 days away. By Wednesday morning, the low should be riding up the East Coast, ending the rain and thunderstorm chances for our area. 25/Owen && .AVIATION... 12Z TAF Discussion. Clouds will slowly increase across central AL from top down as tropical moisture spreads into the area. A slow moving upper low over New Mexico will draw moisture northward from the Gulf of Mexico and zonal flow aloft will transport the moisture eastward into Alabama. Mostly mid to high level clouds will persist thru the period, although cigs arnd 4-5 thousand feet could develop after 03z. The dry airmass below 850mb will keep pcpn mostly in the form of light showers, but a few storms may develop during the heating of the day, mainly from 18z thru 23z. 58/rose && .FIRE WEATHER... Gradual transition to a more moist environment beginning late today and continuing through the rest of the week. While KBDI values remain over 300 today for much of the area, 20 foot winds are not expected to reach critical values. Humidity will be on the rise starting today and tomorrow. Wetting rains are likely for the latter half of the week into this weekend. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 86 68 81 67 80 / 40 40 60 60 80 Anniston 89 69 80 68 81 / 40 40 60 60 80 Birmingham 91 71 80 69 81 / 40 40 60 60 80 Tuscaloosa 92 72 79 71 83 / 50 50 60 60 80 Calera 90 70 80 68 81 / 40 40 60 60 80 Auburn 90 71 81 68 79 / 40 30 60 60 80 Montgomery 93 72 82 70 82 / 40 40 60 60 80 Troy 92 71 82 70 81 / 40 40 60 60 80 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$