Area Forecast Discussion
Issued by NWS Birmingham, AL
Issued by NWS Birmingham, AL
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830 FXUS64 KBMX 040903 AFDBMX Area Forecast Discussion National Weather Service Birmingham AL 403 AM CDT Sat May 4 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Today through Sunday) Issued at 322 AM CDT SAT MAY 4 2024 Despite several rounds of showers with embedded thunderstorms the past few days, rainfall amounts have been sparse for most areas. It looks like this trend will continue through the weekend with somewhat disorganized showers and thunderstorms each day. For this morning, radar imagery shows an upper low over Central Alabama near the I-65 corridor. On the back side of the upper low, skies have cleared over eastern MS and western AL. Fog has developed in these areas and a dense fog advisory may be needed for the far western counties of Central Alabama. Scattered to numerous showers with isolated thunderstorms will continue on the eastern side of the upper low, with the activity shifting out of east Alabama by late this morning. Some convection on the southwest flank of the upper low may develop this afternoon, and kept higher pops across the northeast counties. Only isolated convection expected overnight and into Sunday morning. Diurnal heating on Sunday may bring a slight increase in afternoon thunderstorms, with models hinting at a disturbance over northern MS Sunday afternoon, possibly impacting the northwest counties of Alabama later in the day. 58/rose && .LONG TERM... (Sunday night through next Friday) Issued at 322 AM CDT SAT MAY 4 2024 A weak southern stream shortwave currently along the Arizona/Mexico border will trigger considerable convection along the West Texas dry line today, eventually growing upscale into an MCS across Central Texas. The resulting MCV/shortwave trough will reach Alabama by Sunday evening, triggering scattered to numerous showers and storms with PWATs near 1.75 inches, though any heavier rainfall will be very isolated. Some of this activity may linger into Monday morning in the northeast counties. Depending on how quickly the shortwave exits to the east, subsidence may suppress convection across much of Central Alabama Monday afternoon or at least keep it isolated to widely scattered. This may warrant a decrease in PoPs in later updates. Another shortwave moves through Monday evening but will be much weaker as ridging builds over the eastern CONUS, with only slight chance PoPs in the forecast. Meanwhile a deep trough will be digging across the western CONUS and Plains with ridging building further east. A subtropical ridge will also be strengthening over the southwestern Gulf. Rising 500mb heights across Central Alabama will be a limiting factor for convection on Tuesday, though some guidance does indicate a pre- frontal moisture axis that could trigger isolated to widely scattered convection. Strengthening low-level southwesterly flow will result in warming temperatures. The mid-level ridge axis pushes east of the area Wednesday as the trough becomes positively tilted from Ontario towards the Four Corners, but mid-levels remain warm and fairly dry limiting convective development. Meanwhile a stalled out front just northwest of the Ozarks may begin to advance as a cold front Wednesday night in the wake of low pressure moving through the Ohio Valley. One or more MCSs will probably develop off to our northwest. Will have to keep an eye on them towards the overnight hours given increasing bulk shear, though they may remain just north of the area given westerly flow aloft and better height falls remaining north of the area. Mid-level troughing remains over the Midwest and Great Lakes Thursday while weakening further to the west. The ridge over Central Alabama will begin to flatten by Thursday night. A fairly strong cold front for May will begin to move in by Thursday night. A strong EML and associated steep mid-level lapse rates will result in a very unstable air mass south of the front with 0-6km bulk shear values around 50 kts. This will result in the potential for large hail and damaging winds with any storms or MCSs that develop. Limiting factors will be whether any leftover cold pools from Wednesday night`s MCS(s) limit destabilization, and a tendency for better forcing to remain north of Central Alabama. Still, will need to monitor the potential for severe storms and heavier rainfall as we get closer and the mesoscale details become clearer. Models vary regarding how quickly the front clears the area Friday, but it does look like we should see some pleasant spring weather by next weekend after we get through summer-like conditions the next few days. 32/Davis && .AVIATION... (06Z TAFS) Issued at 1228 AM CDT SAT MAY 4 2024 A moist low level air mass will persist over Alabama thru 15Z. An upper level low currently over Alabama will produce sct to nmrs mostly light showers along and east of I-65 thru 18Z, with sct shwrs and isolated TSRA east of I-65 after 18Z. Vsbys not likely to fall below 3 miles with any shower or tstm. Mostly mid level clouds thru 09Z, with widespread MVFR cigs and lcl IFR cigs north of I-85 from 10Z thru 15Z. VFR cigs expected after 15Z. 58/rose && .FIRE WEATHER... Periods of showers and storms are forecast through Monday. Given the scattered nature of the activity, rain amounts will average near one-half inch, with higher amounts where thunderstorms track. With increasing moisture, minimum RH values will be above 40 percent each afternoon. 20-foot winds should average less than 10 mph from the south to southwest, though could gust to around 25 mph and be variable in direction in or near thunderstorms. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 82 62 85 63 / 40 30 50 60 Anniston 82 64 85 64 / 40 20 40 60 Birmingham 84 66 85 66 / 20 10 40 60 Tuscaloosa 85 66 86 66 / 20 10 40 60 Calera 83 66 84 66 / 20 10 40 50 Auburn 82 67 84 66 / 20 20 40 40 Montgomery 87 67 87 66 / 20 10 40 40 Troy 87 66 87 65 / 20 10 40 30 && .BMX WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 9 AM CDT this morning for the following counties: Fayette-Greene-Hale-Lamar-Marengo-Marion-Pickens- Sumter-Tuscaloosa-Walker-Winston. && $$ SHORT TERM...58/rose LONG TERM....32/Davis AVIATION...58