932 FXUS64 KBMX 241416 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 916 AM CDT Thu Sep 24 2020 .SHORT TERM... /Updated at 0857 AM CDT Thu Sep 24 2020/ Analysis. The remnants of Beta were continuing to move northeast with the center of low pressure analyzed over Central Mississippi. The heavier precipitation continues to reside to the east and northeast of the circulation center. The heavier precipitation has been mainly across our northwest counties. Our hydrologist has indicated that radar estimates are on the high side compared to observation data with roughly 1.5 to 2.5 inches of rain falling over our far northwest counties. The 24/12z BMX sounding is fairly moist from the surface up to 250 mb with layer precipitable water values just shy of 2.0 inches. Dynamically speaking, the better wind shear is co-located with the surface low and points to the south and east. Instability values are extremely low across Central Alabama this morning but higher values exist to our south across Coastal Alabama into the Western Florida Panhandle Forecast. Expect the low center over Central Mississippi to continue to move northeast, becoming positioned in the vicinity of Hamilton toward 3 pm today. The best risk for heavy rain will be across the northwest corner of the forecast area, however, much of the heaviest precipitation is already impacting this area and the storm motion is preventing this activity from leading to any serious flood concerns. We will continue to monitor this area for flash flood concerns. Less precipitation is occurring generally south of the Interstate 59 corridor and the more moist and unstable marine airmass has moved into the far southern portion of the state into the Florida Panhandle. We will be monitoring potential for cloud breaks along with destabilization through warm advection from the south/southeast over the next few hours across our southern counties. We are maintaining a low end risk for a few strong to severe storms this afternoon and evening with some tornado potential given the higher shear values. This environment that will be at least marginally favorable is forecast to creep northward from the Coastal portion of the state into our far southern counties very late this morning into the early afternoon and may make it to the Interstate 59 corridor by late afternoon. Temperatures will be largely dependent on cloud cover, precipitation quality of advection. Lower temperatures will reside to the northwest while higher temperatures are forecast across the southern and southeast counties. Further updates to the forecast will be made as we evaluate this morning's new model output. 05 Previous Short-Term Forecast... .SHORT TERM... /Updated at 257 AM CDT Thu Sep 24 2020/ The I-20 corridor seems to be a good breaking point for the forecast and current radar trends this morning. All models are way under estimating the coverage and overall extent of the rain. They are also behind on the overall timing by about 3 hours. The main circulation with the remnants of Beta is now approaching Jackson, MS as of 3 AM and will continue to spread north and east through the morning and into the afternoon. Look for the circulation to be in the northwestern portions of Central Alabama by 9 to 10 AM this morning and then slowly push east-northeast through the day. Went ahead and raised PoPs as much as possible in the north with this trend and extended likely PoPs further south with the inflow into the main circulation. Looks like we may begin to get some drier air filtering into the backside of the low by the afternoon in the southwest so started backing off rain chances after 4pm here. As the warm front lifts northward this morning, low 70s dew points will lift northward with the warm sector setting up along/south of I-20 where CAPE values will rise to 1000-2000 J/kg with a little bit of daytime heating. The better low to mid-level flow and associated shear will be lifting out of the area this morning and mainly remain north of the warm front. Still, 0-6 km shear values during the afternoon will be around 30-40 kts with 0-1km SRH values around 150 to 200 m2/s2 and backed surface winds. CAMs generally indicate a low- topped convective line with possible embedded mini-supercells along the cold front and leading edge of the mid-level dry intrusion, and a couple cells could also develop ahead of the line. This will result in a marginal risk for a brief tornado, and possibly an isolated damaging wind gust, beginning as early as noon in the southwest and lasting as late as 10 PM in the east. Risk will be tempered by warming mid-levels and neutral to slightly rising 500mb heights in the wake of this morning's activity. Regarding rainfall, a small area of our far northwest counties may see storm total amounts of 2 to 4 inches. This could cause isolated flash flooding but high FFG/recent dryness will be a limiting factor, and coverage/confidence of flash flooding is too low for a flash flood watch at this time. Elsewhere, rainfall amounts are expected to be mainly less than 1.5 inches, with only minor flooding of poor drainage areas/urban areas possible. As we move into the evening hours precipitation will be mainly focused with the low itself in the northeast, so went with higher PoPs here and with the inflow into the low in the southeast. Highest rain chances will be before Midnight and we will see a waning of showers and storms fairly quickly after that. As the precipitation moves out, we will see low clouds in place and possibly the potential of fog developing. The low clouds will be slow to move out on Friday, so look for a cloudy start to the day with rain chances generally only east of I-65. There still could be an isolated shower or two around in the east the afternoon, so continued with that mentioned through 00z 16/32 .LONG TERM... /Updated at 0258 AM CDT Thu Sep 24 2020/ Friday night through Wednesday. Shortwave ridging will develop over the area Friday night ahead of an upper low that closes off over Texas. Very dry mid-level air will be present Friday night/Saturday, though some low-level moisture will linger. Expect mainly dry conditions during this time though a couple sprinkles/drizzle patches can't be ruled out. High temperatures Saturday will be dependent on whether a post- frontal stratus deck can mix out. High clouds will increase Saturday night ahead of the upper low. The upper low will open up into a shortwave trough and move through the area Sunday/Sunday night. Models are trending a little stronger with this wave with a little more moisture return though moisture still remains limited. Have included an isolated to widely scattered mention of showers/storms with this feature Sunday afternoon. Behind the southern stream wave, a stronger northern stream trough will begin to amplify across the eastern CONUS on Monday. An initial cold frontal passage is expected during the Monday/Monday night timeframe, but models disagree on moisture return ahead of the front and in the wake of the southern stream system. The pattern continues to amplify through the rest of the forecast period, with a stronger cold frontal passage in the Tuesday/Wednesday timeframe just in time for the beginning of October. 32/Davis && .AVIATION... 12Z TAF Discussion. Clouds will continue to drop through the rest of the overnight hours and will become MVFR this morning across the north and then remain through a good portion of this period. They are forecast to drop to IFR in the 18 to 24 hour window and added that in at the end of the cycle. We may even dip occasionally into the IFR at times with heavier rain. The remnants of Beta will move through the area today. Some thunder is also possible, but due to the lack of coverage went with VCTS for the afternoon across the north and PROB30 in the south. Winds will generally be east southeast through 15 to 16z, then veering through the day as the low moves by. Generally look for an average of around 10kts with a few gusts to 20 kts possible. 16 && .FIRE WEATHER... Widespread showers and a few thunderstorms are expected today, with rain ending from west to east late tonight through Friday afternoon. Mainly dry conditions are expected Saturday, with small rain chances returning Sunday and Monday ahead of a cold front. Afternoon relative humidity values will remain above 50 percent through Monday. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 73 65 78 61 83 / 100 100 30 10 10 Anniston 76 67 79 63 83 / 100 90 30 10 10 Birmingham 76 66 78 63 83 / 100 90 20 10 10 Tuscaloosa 78 66 80 63 84 / 100 50 10 10 10 Calera 77 66 78 63 82 / 90 80 20 10 10 Auburn 76 68 80 63 82 / 80 70 30 10 10 Montgomery 82 68 82 65 83 / 90 60 20 10 10 Troy 81 69 82 65 83 / 80 60 20 10 10 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$