509 FXUS64 KBMX 210925 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 325 AM CST Fri Dec 21 2018 .SHORT TERM... Today through Saturday night. Regional radar currently shows scattered to numerous rain showers across much of the state. Rain showers will decrease from west to east today as the upper low progresses northeast. The tightening pressure gradient on the back side of the surface low will allow for surface wind gusts 20-30mph throughout the day. Overall, temperatures will be cooler due to a greater influence of cold air advection. River fog cannot be ruled out tonight as clouds clear out and winds become light. Forecast soundings indicate the airmass will become very dry just above the surface. Higher boundary layer winds will also keep fog confined to mainly water bodies. Saturday looks to be dry with high temperatures in the middle to upper 50's. The next chance for a few showers will be early Sunday morning as a weak surface low moves across northern Mississippi. Weak warm advection, 60% RH values and PWAT values 0.75-0.8 could support a chance of a few showers in our northwest counties. Surface temperatures Saturday night will be warm enough across the northwest counties to keep precipitation in liquid form. 07 .LONG TERM... Sunday through Tuesday. Much of the country will be under an upper-level split-flow regime with no particulary amplified troughs/ridges heading into Sunday and early next week. This setup will act as a broad thoroughfare for transient shortwaves to traverse from west to east across the eastern two-thirds of the US. The first and more prominent shortwave is expected to approach our region in the Sunday timeframe where downstream airmass modification supports enough moisture return to produce scattered light rain showers across central Alabama. Most of this light rain activity should stay focused along a weak low pressure area and associated frontal boundary and should be near the I-20 corridor ~12 PM Sunday. A southeastward progression is expected with diminishing coverage/intensity of rain showers heading into the overnight hours. Cooler & drier air advects into the region as a stable continental airmass/high pressure area settles across the southeastern CONUS into Christmas Day. Another perturbation is expected to pass by to our north on the holiday and bring the possibility of an isolated shower to the area, but moisture will remain limited due to the antecedent high pressure system. Highs in the 50s/60s will be the overall theme in the afternoon though temperatures will be a little cooler in areas receiving cloud cover & light rain Sunday/Monday. Wednesday through Friday. There are continued indications of a more potent & amplified disturbance to enter the Desert Southwest around Wednesday. Downstream conditions will undergo broad moisture/temperature increases as mid/upper-level ridging develops across the Southern Gulf Coast states. This sets the stage for the busy upper- tropospheric circulation to tap into northwestern Gulf moisture as the trough ejects from the southern Rockies into the Plains by Thursday. With low predictability within the split-flow regime this far out it's difficult to forecast the trajectory of the wave and where associated cyclogenesis/surface features develop. So, the general theme of the long-term forecast is best advertised as a period of wet & unsettled weather to move into our area, particularly in the Thursday/Friday timeframe. A slight chance of thunderstorms has been introduced on Thursday given the overall evolving synoptic pattern indicating the potential for instability to become available as well. For now the primary threat will be periods of moderate/heavy rainfall to affect the area and further support a continuance of the busy hemispheric pattern & above average precipitation for central Alabama. 40/Sizemore && .AVIATION... 06Z TAF Discussion. The rain will continue off and on through tonight and Friday morning. LIFR to IFR cigs will be present during the overnight. Gusty winds will develop toward morning as well. As the system progresses eastward during the day, the rain will push east with it with it and cigs should become MVFR for the later half of the forecast during the early afternoon. 08 && .FIRE WEATHER... Cloudy skies and light rain will prevail today before beginning to taper off towards the northeast into the overnight hours. A brief period of clearer skies and drier weather is expected on Saturday before scattered light rain showers develop on Sunday. With expected rainfall and relative humidity values remaining above critical values, there are no fire weather concerns at this time. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 45 30 50 34 54 / 70 10 0 10 30 Anniston 47 31 52 35 56 / 70 10 10 0 30 Birmingham 45 32 53 40 56 / 70 10 0 10 30 Tuscaloosa 45 32 56 41 60 / 50 0 0 10 20 Calera 45 31 53 38 58 / 70 10 0 0 20 Auburn 47 33 52 37 59 / 70 10 0 0 20 Montgomery 47 33 56 37 65 / 60 0 0 0 20 Troy 47 34 56 36 65 / 60 0 0 0 10 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$