NWS BMX AFD
A SEVERE WEATHER EVENT STILL APPEARS POSSIBLE ON SUNDAY AS A WARM
FRONT BEGINS TO MOVE NORTHWARD IN ADVANCE OF AN APPROACHING
SHORTWAVE AND UPPER-LEVEL JET STREAK. HOWEVER, THE ECMWF WHICH HAS
BEEN THE MOST BULLISH AND CONSISTENT FOR SEVERAL RUNS, HAS
TRENDED TOWARD A SLIGHTLY FLATTER SOLUTION. NAM AND SREF GUIDANCE
SUPPORTS THE ECMWF SOLUTION, WHILE THE GFS REMAINS THE LEAST
AGGRESSIVE WITH HARDLY ANY SURFACE LOW TO BE FOUND. CURRENTLY, THE
GFS SOLUTION APPEARS TO BE AN OUTLIER, BUT IT MAY REPRESENT A
REALISTIC OUTCOME IF A SUBTROPICAL DISTURBANCE AHEAD OF THE MAIN
SHORTWAVE LEADS TO DISRUPTIVE CONVECTION.
THE NORTHWARD EXTENT OF THE WARM SECTOR REMAINS IN QUESTION, BUT
OUR FORECAST WILL INDICATE AN EFFECTIVE WARM FRONT BECOMING
ESTABLISHED NEAR I-20 ON SUNDAY AFTERNOON. MID 60S DEWPOINTS AND
RELATIVELY COLD 500-300MB TEMPERATURES WILL SUPPORT SBCAPE VALUES
OF 1000-2000 J/KG WITH CAPE EXTENDING UP TO THE 250MB LEVEL. THIS
WILL FAVOR DEEP CONVECTION NEAR THE EFFECTIVE WARM FRONT AND ALONG
AN ADVANCING COLD FRONT. WARM SECTOR DEVELOPMENT IS ALSO POSSIBLE
IN THE AFTERNOON AND EARLY EVENING WITH THE AID OF AN APPROACHING
500MB SHORTWAVE AND DIFFLUENT 300 MB JET. STRONG WESTERLY 0-6 KM
SHEAR ORIENTED ACROSS THE COLD FRONT SUGGESTS STORMS ALONG A
CONVECTIVE AXIS COULD TRANSITION INTO A MIX OF LINE SEGMENTS AND
SUPERCELLS. EVEN THOUGH SURFACE WINDS ARE EXPECTED TO BE FROM THE
SSW, STRONG 0-1 KM SHEAR AND HODOGRAPH CURVATURE SHOULD RESULT IN
0-1 SRH OF 300-400 M2/S2 AND A THREAT FOR TORNADOES IN ADDITION TO
A THREAT FOR DAMAGING WINDS. FORECAST CONFIDENCE REMAINS LOWER FOR
AREAS BETWEEN MONTGOMERY AND BIRMINGHAM, BUT IS LIKELY THAT AT
LEAST THE SOUTHERN THIRD OF THE FORECAST AREA WILL HAVE A SEVERE
WEATHER THREAT.