882 FXUS64 KBMX 211722 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 1222 PM CDT Tue Apr 21 2020 .UPDATE... For 18Z Aviation. && .SYNOPSIS... An upper low was situated over Southeast Canada with an upper trough extending south into the Mid Atlantic States. Shortwave ridging was prevalent across the Southern and Central Plains while a positive-tilted trough was present over Northern Arizona. A surface low was located over the four corners regions with a warm front extending southeast through New Mexico and into Southern Texas. Surface high pressure was centered over Southwest Mississippi while troughing was present on the lee side of the Appalachians. 05 && .SHORT TERM... /Updated at 1042 AM CDT Tue Apr 21 2020/ Today through Wednesday. The forecast remains on track for a pleasant day across Central Alabama as surface high pressure remains nearby. A reinforcing shot of dry air will arrive as a dry cold front passes through the area this afternoon. Expect fair skies this afternoon with highs ranging from the mid 70's far north and in the higher elevations east to readings in the low 80s far south. East to southeast winds will be 6-12 mph with some breezy conditions up to 20 mph at times. A few more high clouds will stream over the area tonight with lows ranging from the low 40s north and east with a few upper 30s possible in the normally colder valley locations while readings will be in the low 50s far south and southwest. We will have southeast winds 5-10 mph overnight. Expect continued increasing clouds into Wednesday with an increasing chance of showers and thunderstorms northwest during the afternoon hours but the heavier activity is expected to move into the area later in the evening. Highs will range from the low 70s north to near 80 south. Winds will be out of the south to southwest 10-20 mph. 05 .LONG TERM... /Updated at 0422 AM CDT Tue Apr 21 2020/ Wednesday night through Monday. The suppressed weather pattern will feature a low-amplitude trough Wednesday night into Thursday across the Lower Mississippi Valley and eastward into Alabama. A residual low theta-e airmass will be in place with a pinched warm sector to our west. Storms are expected to move across LA and MS in the 7 PM to 4 AM time frame and become elevated as they move into Alabama. There may be a non-zero threat for damaging winds and quarter size hail with this activity between 4 AM and 10 AM. This lead impulse will greatly impact the prospects for severe weather from the late morning into the afternoon on Thursday. Models have trended a bit slower with the 500 mb trough and surface low which could allow for greater refocusing along the cold front. The 12 km NAM is very bullish with eye-popping parameters based on an idealistic scenario, the kind that rarely seem to verify. At this time, this has a low probability of occurring, but if it does, a significant tornado threat would be on the table. Many times the 12 km NAM's convective scheme minimizes the impact of the lead impulse, and this could very well be case in this situation. The most likely scenario is for morning storms to result in an effective warm front across the middle of our area, with veered surface winds across the warm sector. However, substantial instability is likely to develop by early afternoon across the warm sector, with CAPE of 2500-3500 J/kg and strong 0-6 km shear in place. Storm initiation will depend on how much low-level convergence can develop behind the morning storms. Any storms in this environment will be capable of producing damaging winds, large hail, and perhaps a tornado. Friday should be dry in between weather systems, but another upstream shortwave will affect the region Friday night into early Saturday. Moisture return ahead of this system appears limited, but showers and storms could form within a narrow axis of instability. If moisture return trends upward, a few strong to severe storms could occur. Saturday afternoon through Monday should be dry and mild with high pressure in place. 87/Grantham && .AVIATION... 18Z TAF Discussion. VFR conditions will prevail through Wednesday morning. Expect no restrictions this afternoon and evening with only a few high to mid level clouds across the area today and tonight. Low- level winds will be breezy out of the east 10-15 kts generally, becoming southeast later this afternoon. Low-level winds will become more southerly overnight 4-8 kts generally. Expect continued increasing clouds in the mid and lower levels through the day Wednesday with increasing RA/TS chances north and west just after this cycle period. Low-level winds will become more southwest during the day Wednesday from 10-15 kts generally. AMD NOT SKED will continue for ASN until further notice due to persisting communication issues. 05 && .FIRE WEATHER... Dry conditions will continue through Wednesday. Afternoon humidity levels will fall to 35 to 45 percent this afternoon and again on Wednesday. Patchy fog this morning will dissipate fairly quickly. The next storm system will move into the region Wednesday night into Thursday. Additional heavy rain will be possible with this system. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 76 43 71 54 72 / 0 0 20 90 100 Anniston 77 44 73 55 73 / 0 0 20 90 100 Birmingham 78 49 73 57 74 / 0 0 20 90 100 Tuscaloosa 79 49 75 59 77 / 0 0 20 100 80 Calera 78 48 74 57 75 / 0 0 10 90 90 Auburn 77 49 74 58 73 / 0 0 0 70 100 Montgomery 81 51 78 62 79 / 0 0 0 80 100 Troy 81 52 79 62 78 / 0 0 0 60 100 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$