104 FXUS64 KBMX 072007 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 207 PM CST Sat Dec 7 2019 .SHORT TERM... /Updated at 0149 PM CST Sat Dec 07 2019/ Through Tonight Low level, moist easterly flow has allowed for continued cloud cover across portions of the area, focused along a weak inverted trough. This trough will shift westward tonight, and with low level flow shifting to the south, and expect skies to remain partly cloudy overnight, but rain-free. Temperatures will range from the mid 40s north and east to lower 50s elsewhere. 14 .LONG TERM... /Updated at 0149 PM CST Sat Dec 07 2019/ Adjusted the forecast in the Tuesday to Wednesday timeframe, to account for changes in model trends showing rainfall lingering slightly longer past midnight. Models continue to show moisture moving out before cold air arrives Wednesday, or have trended warmer overall. Will maintain no mention of accumulating winter precip. 14 /Updated at 0355 AM CST Sat Dec 07 2019/ Sunday through Friday. Relatively active weather is expected across the CONUS for the upcoming work week as a result of several mid/upper-level shortwaves to traverse the country. This will produce a period a wet weather to begin overnight Sunday in the form of isolated light rain showers via the onset of low-level WAA across Central Alabama. This activity will gradually peak in coverage/intensity on Tuesday, and eventually clear the area to the southeast on Wednesday ahead of a stout cold front. Thereafter, a second round of wet weather is possible for the late Thursday through early Saturday timeframe. By Sunday morning a rather complex upper-level pattern is progged to continue evolving across the country. A sharp trough is forecast to begin digging across the West Coast with a low amplitude/downstream jet streak positioning across the souther tier of the country. Through time the trough is expected to become more amplified with southwesterly flow aloft overspreading the Southeast with a sub- tropical ridge near the northern Caribbean. By Tuesday morning this places favorable synoptic scale lift via the right entrance region of the jet streak to our north, as well as continuation of low-level WAA. Peak coverage of rainfall is forecast through Tuesday evening as additional forcing from the advancing shortwave provides PVA and a deformation axis from the TX Gulf Coast northeastward through the southern Appalachians. PWs are expected to rise to the 1.3-1.5" range during this time, which is plenty to support widespread rain chances. However, totals are forecast to remain at or below an inch at this time as convection remains quite limited due to little instability, even aloft. With the cold front forecast to continue southeastward across Central Alabama through the afternoon, aforementioned forcing aloft will provide needed support for over- running rain showers through the evening. However, the Canadian airmass will not bring sub-freezing temperatures into the area until early Wednesday morning. By this time the trough axis passes to our east & associated subsidence will signal the end of rainfall as the much cooler/drier airmass takes over with high pressure. Forecast details with this system will continue to be tweaked in the coming days. For now, any wintry precipitation that may occur in the cold airmass will be negligible (as with the last case of isolated flurries). After frontal passage on Wednesday, highs in the 40s/50s are forecast through the end of the forecast period. High pressure will keep weather conditions relatively quiet through around Friday whereas another potent shortwave is expected to approach from the west. This will support another period of wet weather as an associated low pressure system develops across the region. For now, PoPs have been truncated to <40% as forecast certainty remain low this far out. 40/Sizemore && .AVIATION... 18Z TAF Discussion. VFR conditions are expected through Sunday morning at all TAF sites. Due to the winds remaining light...and increasing cloud coverage...fog development is not expected at this time. After sunrise Sunday...introduced MVFR ceilings at KMGM and KTOI due to increasing moisture and chance for scattered showers through the rest of the TAF period. Only included VCSH for now due to uncertainty in coverage and timing. 24 && .FIRE WEATHER... Cloud cover is expected to increase tonight, as low level winds become southerly, with best cloud cover across the south. Ceiling heights should remain at or above 3kft. A slight chance of light rain showers is forecast again on Sunday with more widespread rainfall expected Monday night into Wednesday. There are no fire weather concerns at this time. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 45 58 49 68 57 / 10 20 50 40 80 Anniston 48 59 50 70 58 / 10 20 50 30 70 Birmingham 48 61 53 68 58 / 10 20 40 30 80 Tuscaloosa 50 64 53 70 58 / 10 20 30 30 80 Calera 49 61 52 69 59 / 10 20 40 20 70 Auburn 48 58 52 69 59 / 10 20 40 30 50 Montgomery 52 64 55 74 60 / 10 20 30 20 50 Troy 51 64 55 74 60 / 10 20 30 20 40 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$