920 FXUS64 KBMX 250537 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 1137 PM CST Sun Nov 24 2019 .UPDATE... For 06Z Aviation. && .SHORT TERM... /Updated at 0232 PM CST Sun Nov 24 2019/ Through Tonight. Surface high pressure dominates weather along the northern Gulf Coast today, with now clear skies across Central Alabama and occasionally breezy west to northwesterly winds. Dewpoints have fallen into the mid 30s and lower 40s. With clear skies overnight, lower moisture, and light winds, temperatures will fall into the mid 30s overnight. Not confident in widespread fog development late tonight to include at this time. Any development will likely be light and localized. 14 .LONG TERM... /Updated at 0232 PM CST Sun Nov 24 2019/ PoPs in the extended forecast continued to trend upwards in this update with two separate frontal systems expected through the week. Guidance is in better temporal agreement on the first front passing through Central AL during the day on Wednesday. Rain chances were increased for this time frame with numerous to likely rain showers expected to move west to east through the forecast area before clearing out by Wednesday night after frontal passage. As mentioned in the previous extended forecast discussion below, a few rumbles of thunder will be possible, but instability values continue to appear too low to support an organized severe risk despite sufficient shear profiles. Similarly, PoPs were raised slightly for the weekend system, particularly on Sunday night. This system will continue to be monitored, but like the last, the atmosphere will have a difficult time destabilizing to support an organized severe threat, so will continue to forego mentioning it in the HWO for now. 86 /Updated at 0343 AM CST Sun Nov 24 2019/ Monday through Wednesday: Quasi-zonal but broadly cyclonic flow will be in place aloft on Monday, downstream of a trough digging into the Four Corners region. A weak wave in the subtropical jet will provide a few high clouds. Southwesterly low-level flow and associated warm advection should allow high temperatures to reach the high side of guidance: the mid to upper 60s. Winds will remain southerly overnight but light, allowing temperatures to fall into the low 40s with some 30s in typically cooler locations. Clouds will begin to increase late in the night. A low-amplitude trough and embedded upper low and a surface low will lift from the High Plains to near Lake Michigan Tuesday/Tuesday night, causing a cold front to move through Central Alabama very late Tuesday night through Wednesday. An intense 135kt mid-level jet streak on the trough's southern flank will lift across the Ozarks to the Ohio Valley Tuesday night. A 45-50kt LLJ will move from the Lower Mississippi Valley to Alabama Tuesday night. Various subtropical impulses in the southwest flow aloft will move across Central Alabama during the day on Tuesday. The associated increase in mid-level moisture/isentropic lift will result in rain chances increasing Tuesday afternoon, especially in the northwest counties as profiles become saturated. Several limiting factors are expected to prevent a threat of severe storms despite favorable shear profiles for supercells. The main limiting factor will be instability. Moisture return in the wake of the current cold frontal passage over the Gulf will be limited, with dew points remaining in the 50s during the afternoon and early evening hours. As low 60s dew points begin to move in during the late evening and overnight hours, weak mainly elevated instability may develop allowing for isolated thunder but surface- based CAPE will be negligible, with precipitation associated with the subtropical impulses also serving as a stabilization factor. By the time higher dew points arrive early Wednesday morning, low- level flow will be veering and weakening. In addition, notable 500mb height rises indicative of synoptic subsidence will be present throughout the event as a subtropical ridge centered near Cuba strengthens, and the trough lifts away from the area. Therefore, severe storms are not expected at this time, with any stronger activity that develops off to our west expected to weaken as it arrives, but will continue to monitor. Plentiful moisture with PWATs around 1.85 inches will be present along with enough low to mid- level lift to support widespread precipitation Tuesday night and Wednesday. Temperatures will also warm into the 70s across the southern counties Tuesday and Wednesday due to southerly flow ahead of the front. Thursday through Sunday: A strong 593 decameter subtropical ridge will strengthen over the Gulf Thursday/Friday, with a ridge axis extending northward across the eastern CONUS. The front will stall near the Gulf Coast by Thursday as it encounters the ridge, before beginning to lift northward as a warm front on Friday. This will result in cooler temperatures on Thursday and a warming trend for Friday, though easterly flow north of the front will prevent more significant warming. Another deep trough digging along the West Coast will cause the cutoff low currently well west of the Baja peninsula to eject northeastward with its remnant vorticity riding over the ridge. Mid-level isentropic lift/warm advection may allow for some rain to clip some of our northern counties Thursday night/Friday, though the bulk of the rain appears that it will remain northwest of the area. The large trough over the western CONUS will eventually push eastward and break down the ridge next weekend, sending another low pressure system from the Plains to the Midwest with a trailing cold front. Typical uncertainties exist with the speed of this system, and suspect the slower solutions may be more likely given the strength of the ridge. It appears that this system will have more moisture/instability than previous systems as the mid-week cold front will not make it all the way through the Gulf, especially if the slower solutions are correct. There are also some indications of steeper mid-level lapse rates associated with an EML. At this time predictability is too low to mention in the HWO this far out but will keep an eye on it. 32/Davis && .AVIATION... 06Z TAF Discussion. A dome of high pressure has settled over Alabama producing mostly clear skies and calm winds. Very cold air near the surface has produced a very shallow layer of nearly saturated conds. Fog has already formed along several of the waterways, including the Black Warrior River. KTCL is close to the Black Warrior River, and vsbys have dropped to 3 miles. Expect other airports sites to experience MVFR vsbys overnight, mainly those close to waterways. The fog should burn off by 14z. As the surface high slides off to the east on Monday, sfc winds will become light southerly by 17z. 58/rose && .FIRE WEATHER... Dry and cooler conditions will continue tonight, with a warming trend for Monday and Tuesday. A cold front will bring another round of widespread rain chances late Tuesday afternoon through Wednesday. Critical fire weather conditions are not expected. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 31 61 36 65 56 / 0 0 0 20 80 Anniston 33 62 39 67 56 / 0 0 0 10 70 Birmingham 35 63 43 67 59 / 0 0 0 20 80 Tuscaloosa 33 64 43 70 61 / 0 0 10 30 80 Calera 34 63 41 69 59 / 0 0 0 20 80 Auburn 38 61 41 67 56 / 0 0 0 0 50 Montgomery 36 66 42 74 60 / 0 0 0 10 60 Troy 33 65 42 72 59 / 0 0 0 0 40 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$