National Weather Service Weather Forecast Office

Area Forecast Discussion

958
FXUS64 KHUN 180603 AAC
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
103 AM CDT SAT MAY 18 2013

.UPDATE...
FOR 06Z TAFS

&&

.DISCUSSION...
/ISSUED 1009 PM CDT FRI MAY 17 2013/
SHOWERS ASSOCIATED WITH A CONVECTIVE COMPLEX (WITH A MCS LIKE
APPEARANCE FROM A SATELLITE PERSPECTIVE) WERE EXITING FAR NE
ALABAMA. THROUGHOUT THE EVENT (ACROSS THE TENNESSEE VALLEY)...
LIGHTNING ACTIVITY WAS AT BEST SPORADIC AND MAINLY AFFECTED AREAS
SOUTH OF THE TENNESSEE RIVER. RAINFALL WITH THIS SYSTEM RANGED FROM
1/2 TO ABOUT 1.5 INCHES. AS THEN HEAVIER CONVECTION IN THE SYSTEM
CROSSED THE I-65 CORRIDOR...PRODUCED TWO SHORT LIVED EF-0 TORNADOES.
ONE PRODUCED SPOTTY DAMAGE ON THE EAST SIDE OF ATHENS...AND THE OTHER
NEAR ELKMONT. SEE OUR LATEST PUBLIC INFORMATION STATEMENT FOR MORE
INFORMATION. MORE INFORMATION ABOUT THIS STORM WILL BE POSTED ON OUR
WEBSITE VERY SHORTLY.

IN THE MEANWHILE...A WEAK SOUTHERLY FLOW WAS BRINGING A SUPPLY OF
MOISTURE INLAND FROM THE GULF. THIS MOISTURE AND LIFT PROVIDED BY
PASSING UPPER DISTURBANCES HELPED TO CREATE THE RECENT CONVECTION THE
AREA EXPERIENCED. THE DISTURBANCE...NOW OVER NE AL...AND ITS LOWER
REFLECTION HAD CREATED RATHER HIGH (300-500 M/S) HELICITY VALUES
ACROSS THE REGION EARLIER. SHORT TERM MODEL OUTPUT WAS IN GENERAL
AGREEMENT OF MORE SHOWER/THUNDERSTORM DEVELOPMENT DURING THE
OVERNIGHT...DUE TO MANY INTERACTING BOUNDARIES AND CONTINUED
INSTABILITY. DUE TO A GOOD CHANCE OF MORE SHOWER ACTIVITY...STAYED
WITH LIKELY RAIN CHANCES FOR THE NIGHT TIME. NOT CERTAIN ENOUGH FOR
CATEGORICAL CHANCES...SO TRIMMED THEM DOWN A CATEGORY. HAVE ALSO
ADDED A MENTION OF PATCHY FOG IN FOR THE LATE NIGHT...GIVEN LEFTOVER
MOISTURE FROM THE RECENT RAINS. LOW TEMPERATURE FORECASTS...WINDS...
AND CLOUD COVER LOOK FINE...WITH ONLY A MINOR TWEAK HERE/THERE IN
THOSE AREAS. UPDATED FORECASTS HAVE BEEN ALREADY SENT.

RSB

&&

.AVIATION...
FOR 06Z TAFS...SCTD SHRA/TSRA WILL CONTINUE TO DEVELOP ACROSS THE
REGION THRU TOMORROW AFTN...ASSOC WITH VARIABLE CIGS. WHILE BOTH
SITES ARE CURRENTLY MVFR...IFR/ALT MINS CIGS HAVE DEVELOPED AROUND
THE SHRA/TSRA IN MS/AL. THEREFORE...DO NOT EXPECT MVFR CONDS TO
LINGER LONG. CIGS SHOULD DROP TO AT LEAST IFR OVER THE NEXT SEVERAL
HRS AND COULD DIP BELOW ALT MINS NEARING 12Z. HAVE NOT INCLUDED THIS
IN THE TAFS ATTM BECAUSE OF CHALLENGES IN TIMING THE ONSET. ADDTL
TSRA DEVELOPMENT WILL THEN OCCUR AFTER SUNRISE BUT CIGS SHOULD SLOWLY
IMPROVE THROUGH THE END OF THE PERIOD AS THIS SYSTEM SLIDES EASTWARD
AND AWAY FROM THE TERMINALS.

CCC/DD

&&

.HUN WATCHES/WARNINGS/ADVISORIES...

AL...NONE.

TN...NONE.

&&

$$

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