Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 030233
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
933 PM CDT MON MAY 2 2016

.UPDATE...
EVENING UPDATE.

&&

.DISCUSSION...
AS OF 0230Z...THE BASE OF AN UPPER TROUGH IS MOVING INTO SOUTHEAST
MISSOURI WITH A COLD FRONT NEARLY STATIONARY DRAPED SW TO NE FROM
NEAR BIRMINGHAM UP THROUGH THE NORTHEAST ALABAMA CORNER. LINGERING
SHOWERS ARE CONTINUING ALONG IT AND SLOWLY DISSIPATING AND SHIFTING
SOUTHEAST WITH THE LOSS OF DAYTIME HEATING. A SLIGHTLY DRIER AND
COOLER NW FLOW IS RETURNING BEHIND IT WHICH IS ALSO EVIDENT IN THE
LATEST WATER VAPOR IMAGERY. THIS WILL KEEP SHOWERS AT A MINIMUM
TONIGHT BUT WITH THE UPPER TROUGH STILL TO THE NORTHWEST AND DEW
POINTS REMAINING IN THE UPPER 50S/LOWER 60S...WILL MAINTAIN A SLIGHT
CHANCE POP. THUNDER CHANCES TONIGHT WILL BE LESS THAN 15% SO WILL
NOT INCLUDE IN THE FORECAST AT THIS TIME.

LINGERING MOISTURE AND COOLING TEMPS WILL KEEP LOW CLOUDS OVER THE
AREA TONIGHT. HOWEVER SOME AREAS THAT SEE SOME CLEARING COULD SEE
SOME POCKETS OF FOG BUT CURRENTLY CONFIDENCE IS TOO LOW TO INCLUDE IN
THE GRIDS AT THIS TIME.


LN

&&

.AVIATION...
/ISSUED 645 PM CDT MON MAY 2 2016/
FOR 00Z TAFS...EXPECT THAT BORDERLINE IFR TO MVFR CEILINGS AND MVFR
VISIBILITIES WILL OCCUR AT MSL AFTER 02Z AND AT HSV AFTER 08Z TONIGHT
AS LOW CLOUDS CONTINUE TO STREAM INTO THE AREA. MVFR CEILINGS SHOULD
FINALLY GIVE WAY TO VFR CONDITIONS BETWEEN 15Z-16Z AT MSL AND HSV.

TT

&&

.PREV DISCUSSION...
/ISSUED 401 PM CDT MON MAY 2 2016/
THE LATEST ANALYSIS SHOWS A SYNOPTIC COLD FRONT CURRENTLY SLICING
SW-NE ACROSS THE FORECAST AREA. THE SFC FRONT IS LIKELY ALIGNED
ROUGHLY FROM WINCHESTER, TO HUNTSVILLE TO SMITH LAKE BASED LARGELY ON
WIND SFC OBS. LOWER DEW POINT TEMPS ARE LINGERING A BIT BEHIND THE
SFC FRONT SHIFT AS STRONGEST DP GRADIENTS ARE STILL GENERALLY IN NE
MISS AND SOUTHERN TN. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED IN THE
RELATIVELY THETA-E RICH AIRMASS AHEAD OF THE FRONT DURING THE EARLY
AFTERNOON AND ARE NOW MOVING ACROSS MAINLY THE CENTRAL/EASTERN
PORTIONS OF THE AREA. MLCAPE VALUES PER SPC ANALYSIS HAVE CLIMBED TO
ABOUT 1000-1500 J/KG IN THE WARM SECTOR AHEAD OF THE FRONT, WHICH
HAS AIDED IN TSTORM DEVELOPMENT IN THE AREA. HOWEVER, BROAD SCALE
FORCING FOR ASCENT IS STILL LIMITED AND DEEP LAYER SHEAR IS ALSO
LIMITED AND LARGELY LINEAR. SO, TSTORMS HAVE BEEN GENERALLY WEAK/MDT
IN INTENSITY. FARTHER TO OUR NORTH...BETTER SHEAR HAS ENABLED SOME
STRONG/SEVERE TSTORM DEVELOPMENT IN PARTS OF MIDDLE/EASTERN TN AND
POINTS FARTHER NORTH AND EAST TODAY. NEVERTHELESS...AS PEAK HEATING
IS REALIZED OVER THE NEXT HOUR OR SO...AN ISOLATED STRONG OR SEVERE
THUNDERSTORM MAY STILL BE POSSIBLE IN OUR EASTERN
COUNTIES...PARTICULARLY FROM CULLMAN TO GUNTERSVILLE AND
SCOTTSBORO...AND POINTS EAST. BASED ON FCST/ANALYSIS SOUNDING
INFORMATION AND LATEST RADAR/SATELLITE/LIGHTNING TRENDS...THE MOST
LIKELY IMPACT FROM STRONGER STORMS WOULD BE WIND GUSTS TO 40-50 MPH
AND SMALL HAIL. WILL BE WATCHING FOR STRONGER SEVERE POTENTIAL THOUGH
OVER THE NEXT FEW HOURS.

THE SFC FRONT IS EXPECTED TO MOVE ACROSS THE AREA DURING THE EVENING
EFFECTIVELY SHUTTING OFF SFC BASED INSTABILITY. AS THE COOLER AIRMASS
GRADUALLY MOVES INTO THE AREA AND THE FRONTAL SURFACE UP THROUGH
ABOUT 850-900 MB SLIPS THROUGH...CONVECTIVE POTENTIAL WILL
ESSENTIALLY CEASE FROM NORTHWEST TO SOUTHEAST. THUNDERSTORM CHANCES
WERE REMOVED FROM ABOUT THE WESTERN HALF OF THE AREA FOR THE
EVENING...BUT A SLIGHT CHANCE TO CHANCE MENTION WAS RETAINED FOR
EASTERN LOCATIONS. BROAD/WEAKER FORCING WILL STILL RESULT IN LGT/MDT
SHRA ACTIVITY IN WESTERN AREAS THIS EVENING AS IT CURRENTLY IS TO
OUR WEST. COLD ADVECTION WILL HELP TO SLOWLY PUSH TEMPS INTO THE
MID/UPR 50S TONIGHT...WHILE SHOWER ACTIVITY DIMINISHES FROM WEST TO
EAST LATE.

THE BROAD UPR TROUGH RESPONSIBLE FOR THE INCLEMENT WEATHER THIS
AFTERNOON/EVENING WILL BECOME SHEARED AND MOVE THROUGH THE AREA
TOMORROW. LAPSE RATES WILL STEEPEN IN THE AFTERNOON AS STRONG EARLY
MAY INSOLATION HEATS UP THE BOUNDARY LYR OF THE ADVECTING COOLER
AIRMASS. PARCELS TOMORROW AFTERNOON SHOULD BE SUFFICIENTLY BUOYANT TO
PRODUCE WELL-DEVELOPED CU AND PERHAPS ISOLD LGT SHRA IN EASTERN
AREAS AS THE CORE OF THE UPR TROUGH PIVOTS THROUGH. THUS...WILL
RETAIN A SLIGHT CHANCE POP FOR MAINLY EASTERN AREAS TOMORROW. SB/ML
CAPE MAY REACH THE -10C LEVEL TOMORROW, WHICH COULD RESULT IN -TSRA
ACTIVITY. HOWEVER...GIVEN THE VERY THIN FORECAST CAPE AT THESE
LEVELS...WILL NOT INCLUDE MENTION OF THUNDER AT THIS TIME AS CHANCES
APPEAR VERY SMALL.

THE HIGHLY AMPLIFIED RIDGE IN THE WESTERN CONUS/CANADA WILL LEAD TO
DOWNSTREAM DEEP TROUGHING IN THE EAST WITH ANOTHER UPR COLD CORE LOW
MOVING INTO THE OH/TN VALLEY REGION LATE TUES INTO WED. BOUNDARY LYR
MOISTURE WILL NOT BE AS HIGH AS WED...BUT SHOWERS AGAIN ARE POSSIBLE
AS LOWER LEVEL LAPSE RATES STEEPEN.

DRIER AND RELATIVELY COOL WEATHER IS LIKELY FROM THURSDAY THROUGH
THE WEEKEND AS DEEP NW FLOW BECOMES ENTRENCHED ACROSS THE REGION.
MORNING LOWS ON THURS/FRI MORNINGS WILL LIKELY FALL INTO THE MID/UPR
40S AT MOST LOCATIONS. RECORD LOWS THIS TIME OF YEAR ARE IN THE
30S...SO MORNING LOWS WILL NOT BE NEAR RECORDS BUT STILL ABOUT 10
DEGREES BELOW NORMAL.

AN UPR TROUGH IS EXPECTED TO BEGIN TO EJECT OUT OF THE WEST PERHAPS
AS EARLY AS LATE SUNDAY INTO MONDAY...BRINGING PERHAPS THE NEXT
CHANCE FOR RAIN TO THE AREA EARLY NEXT WEEK.

KDW

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.



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