516 FXUS64 KBMX 141738 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 1138 AM CST Thu Feb 14 2019 .UPDATE... For 18Z Aviation. && .SHORT TERM... Today and Tonight. Expect mostly dry conditions today as high pressure continues to slowly slide eastward. However, clouds will begin increasing from the west due to an approaching upper level jet and a weak short wave. An approaching cold front extending southwestward from a surface low moving through the Great Lakes region will allow for an increase in rain chances to our north just before midnight. High's temperatures will be in the 60's. Temperatures tonight won't be quite as cool due to the increasing cloud cover from the west. Low's will range from low 50's west to upper 40's east. 07 .LONG TERM... Friday through Thursday. Generally zonal flow aloft sets up for the end of the week and into early next week. Within this zonal flow, several shortwave impulses move through the region, each providing lift for numerous rain showers for Central AL. Initially, on Friday, a cold front slowly slides into northern portions of our area, bringing widespread rain by Friday evening. The front continues to push southward late Friday into early Saturday morning. By Saturday, the front is along the Gulf Coast, so we could see a break in the rain during the day. However, another impulse moves through late Saturday night into Sunday, lifting the frontal boundary northward as an effective warm front. Therefore, I've trended PoPs up on Sunday for much of the area. Modest instability could build in across Central AL, so I've continued mentioning a chance for thunderstorms in the forecast, but do not expect any severe potential at this time due to the best dynamic forcing remaining well to the north. Rain chances continue Monday through Thursday of next week, with PoPs ranging from 50-70+%. There will likely be periods where rain chances decrease slightly, but forecasting the exact timing of these shortwave impulses will be difficult beyond 4 days out. The stationary boundary remains draped across the region for most of the time. Locations south of the boundary will see high temps easily reaching into the 70s with locations north of the boundary remaining in the mid to upper 50s. This temperature gradient will likely exist over central AL for much of the upcoming week. Along with the warmer air mass on the south side of the boundary comes the instability, which guidance pretty much agrees on at this point. Therefore, I do expect there to be thunderstorms along and south of the boundary Tuesday through Thursday. If models trend towards one of the impulses causing a significant push in the frontal boundary, we couldn't rule out the chance for some stronger storms. At this time, confidence is just too low to mention any severe potential. Another concern will be the potentially prolonged rainfall Monday through Thursday, with some moderate to heavy rainfall rates occurring at times. Right now, the forecast is for 3-5 inches of rainfall Monday through Wednesday for locations generally north of the highway 80 corridor. Rainfall amounts can be a tricky thing to forecast 5-7 days out with many factors playing a role, but given the prolonged nature of the rainfall, and the potential for heavier rounds training across portions of Central AL, I'll introduce a lower confidence threat of flooding in the HWO for Tuesday and Wednesday. This is when current guidance has some of the heavier rainfall rates moving into the area after we've experienced several rounds of rain over the weekend and into Monday, which should be enough to saturate the soils. 25/Owen && .AVIATION... 18Z TAF Discussion. Area-wide VFR conditions have prevailed so far today, though winds have been on the increase with higher gusts. Expect S to SSE winds into the evening hours before veering more SW by tomorrow morning. Also expecting a decrease in ceiling heights & transition to MVFR/IFR by ~12Z tomorrow as a shortwave trough & frontal boundary develops a stratus layer up to ~850mb. This will also carry the chance for light rain showers & have handled with PROB30s at all sites except MGM/TOI. These two sites may stay in the MVFR range as most activity is currently forecast to stay northward, but have only tried to establish the trends at this point. Otherwise expect southerly winds at 5-9 knots with VFR flight conditions until ~09Z when initial ceilings begin to drop. 40/Sizemore && .FIRE WEATHER... Rain free conditions are expected through today, with min RHs falling to 35-40 percent by the afternoon. Rain chances increase Friday and persist for the most of the upcoming week. There are no fire weather concerns at this time. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 61 48 63 50 61 / 0 30 50 80 20 Anniston 63 49 65 53 66 / 0 30 40 60 30 Birmingham 63 52 65 53 64 / 0 30 40 60 20 Tuscaloosa 66 52 68 53 65 / 0 20 40 60 20 Calera 64 51 66 55 66 / 0 20 30 60 30 Auburn 63 48 66 59 69 / 0 10 20 40 40 Montgomery 68 51 70 61 72 / 0 10 10 40 40 Troy 66 49 71 59 72 / 0 10 10 30 30 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$