408 FXUS64 KBMX 160005 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 705 PM CDT Sat Oct 15 2022 ...New AVIATION... .SHORT TERM... (This afternoon through Sunday) Issued at 1252 PM CDT SAT OCT 15 2022 A PWAT of 0.6 inches was measured on the 12Z BMX RAOB which indicates dry air is still in place over Central AL despite a cluster of showers and thunderstorms over Memphis and northern Mississippi. That activity is associated with a thin corridor of moisture located along a cold front which extends south across the Northeast and into the Tennessee Valley from a low over Ontario. The eastern extent of the showers has been gradually decaying as it moves into the drier air over northwestern Alabama. A few showers may get very close to our northwestern counties later this afternoon, but for now, expecting the activity to diminish before reaching the area with high pressure centered over Georgia and extending west across Alabama. Temperatures are still on track to reach the 80s area-wide this afternoon. The front stalls to our north this evening as it loses upper-level support with flow becoming more westerly aloft over the Tennessee Valley. Temperatures continue to plummet overnight, so went on the cooler side again for lows, but increasing high clouds should help keep most locations in the 50s with localized upper 40s. Mostly dry and warm again tomorrow as the front stays to our north with only a small chance for a shower in the far northwest late in the afternoon. Eventually a surge of higher winds aloft will advect southeastward across the Midwest and give the front the push it needs to get moving again, but this won't occur until Sunday night. 86/Martin && .LONG TERM... (Sunday night through next Friday) Issued at 240 PM CDT SAT OCT 15 2022 Long term forecast trends remain the same this afternoon, as we could be dealing with record cold October temperatures as we approach Wednesday and Thursday of next week. First off, slight chance PoPs remain in the forecast Sunday night through the day on Monday as the highly advertised strong cold front quickly moves south through the area. A few light showers can't be ruled out, but moisture continues to appear very limited. Most locations should remain dry through the day on Monday. All eyes will then be looking toward the arrival of some of the coldest air we've seen on record during the month of October across the Southeast. The highly amplified upper level pattern across the eastern CONUS continues to trend colder and drier on each subsequent global model run. An arctic airmass will dive southward across much of the eastern half of the country Tuesday through Thursday of this upcoming week. Low temperatures have trended even colder on this afternoon's forecast update and many locations will most certainly see the first freeze of the season both Wednesday and Thursday mornings. Widespread frost can be anticipated, especially on Thursday morning as the surface ridge settles across the region and winds are mainly calm with ideal radiational cooling conditions. See the climate section below for upcoming records going into next week. Temperatures could finally begin to modify by the end of next week, but very dry air will remain in place. Elevated fire danger conditions will need to be monitored with dewpoints dropping down into the low to mid 20s. I wouldn't be surprised to see guidance trending toward the teens for dewpoints over the next couple of days given the arctic nature of the air headed southward. 56/GDG Previous long-term discussion: (Sunday night through Friday) Issued at 311 AM CDT SAT OCT 15 2022 A mid-level speed max will push through the area Sunday evening, but the cold front will lag behind, not arriving in the northern counties until after midnight Sunday night. Moisture and lift are very limited with the front, and will just keep in some slight chance PoPs across the far north Sunday night. Lows will be relatively mild in the pre-frontal air mass. The cold front continues to move through the area Monday. Some lower 60s dew points may lift up into the far southern counties, and will continue to mention slight chance PoPs across the south with the front. Strongest cold air advection lags behind the front, so most areas except the far northern counties should reach the 70s for highs. A highly amplified pattern remain in place for much of the week with strong ridges over the western CONUS and Greenland and a deep trough over the eastern CONUS, with a deep upper low near the Great Lakes. This will allow an unseasonably chilly air mass from high latitudes to invade much of the eastern CONUS. Strong cold air advection may result in a light freeze along our northern border late Monday night/Tuesday morning and will add a low confidence mention to the HWO, but winds this night should be strong enough to prevent frost formation. 850mb temps will be in the 1st percentile on Tuesday, as cold as -4C, resulting in high temperatures near record "low highs" in the 50s to low 60s far southeast, and the breezy northerly winds will make it feel cooler than that. Despite the cool temperatures, very low dew points associated with the modified Arctic air mass will result in RH values below 25 percent. Winds will remain a little under red flag warning criteria, but fire danger will still be somewhat elevated. The cool dry air mass will set the stage for an earlier than normal first freeze of the season Tuesday night and Wednesday night. Winds may stay up enough to prevent ideal radiational cooling except in the northern/northeastern counties Tuesday night, but should go calm Wednesday night with a ridge axis overhead and widespread frost also expected. There are some interesting differences between the deterministic NBM low temperatures guidance and the probabilistic NBM low temperature guidance, with the probabilistic being much cooler. This appears to be due to different bias correction methods with other bias- corrected guidance being very cool as well. For now have lows in the upper 20s in the typically cooler spots across the north with low 30s elsewhere, which is still near record lows, but it's possible these could trend downward as we get closer given the tendency for low temperatures to over-perform (be cooler than guidance) in these dry air masses. ECMWF Extreme Forecast Index for both high and low temperatures also indicates the potential for anomalous values. See the climate section for record lows and record cool highs that may be in jeopardy. 32/Davis && .AVIATION... (00Z TAFS) Issued at 625 PM CDT SAT OCT 15 2022 VFR conditions expected this forecast period, as a front remains to our north. Winds will generally be calm overnight, with passing high clouds. Winds will increase during the day Sunday from the southwest, at 4-7kts. 14 && .FIRE WEATHER... RH values are expected to increase slightly during the day on Sunday to 30 to 35 percent south of I-20, and 35 to 45 percent north of I-20. 20ft winds will be southwest 4-7 mph over the weekend. A strong cold front will push through Central Alabama on Monday with much drier air moving southward. Very limited moisture can be expected as the front moves through. && .CLIMATE... Issued at 311 AM CDT SAT OCT 15 2022 Record "cool high" temperatures for October 18: Birmingham: 55 (1955) Tuscaloosa: 58 (1966) Anniston: 54 (1955) Montgomery: 60 (2009) Record lows for October 19: Birmingham: 29 (1948) Tuscaloosa: 28 (1948) Anniston: 30 (1948) Montgomery: 34 (1948) Record lows for October 20: Birmingham: 32 (1964,1913) Tuscaloosa: 32 (1989,1948) Anniston: 29 (1948) Montgomery: 32 (1989) && .PRELIMINARY POINT TEMPS/POPS... Gadsden 49 84 56 71 / 10 10 20 10 Anniston 52 84 57 72 / 0 0 10 20 Birmingham 56 84 59 71 / 0 0 10 10 Tuscaloosa 55 84 60 73 / 0 0 10 20 Calera 54 84 59 73 / 0 0 10 20 Auburn 55 84 61 76 / 0 0 10 20 Montgomery 52 87 61 78 / 0 0 0 20 Troy 51 87 61 79 / 0 0 0 20 && .BMX WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...86 LONG TERM....56 AVIATION...14