Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 312327
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
627 PM CDT TUE MAR 31 2015

.UPDATE...
FOR 00Z TAFS

&&

.DISCUSSION...
/ISSUED 315 PM CDT TUE MAR 31 2015/
THE FRONTAL BOUNDARY THAT MOVED TO THE SOUTH OVERNIGHT BECAME
STATIONARY AND IS NOW SLOWLY MOVING NORTH AS A WARM FRONT/WEAK
SURFACE BOUNDARY EXTENDING FROM A WEAK LOW OVER CENTRAL TEXAS. THE
BOUNDARY IS STRETCHING ALONG THE SOUTHERN HALF OF THE CWA BUT THANKS
TO QUICK HEATING TODAY AND DEW POINTS RISING FROM THE UPPER 40S TO
UPPER 50S/LOWER 60S IN A FEW HOURS...SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED. BOTH SURFACE BASED AND MOST UNSTABLE CAPE IS HIGH AS OF
20Z AS WELL AS STEEP LAPSE RATES. THIS SHOULD KEEP SHOWERS AND
THUNDERSTORMS SCATTERED ACROSS THE AREA WITH THE CHANCE A FEW WILL
BE SEVERE. NOT A WHOLE LOT OF WIND IN THE COLUMN TODAY SO LARGE HAIL
WILL BE THE BIGGEST THREAT. BUT WITH STRONG UPDRAFTS AND HEAVY RAIN
DEVELOPING...GUSTY WINDS WILL BE LIKELY IN THE DOWNDRAFTS. THE LACK
OF A STRONG SURFACE BOUNDARY WILL KEEP THESE THUNDERSTORMS FROM
BEING MORE WIDESPREAD IN OUR FORECAST AREA.

A BRIEF BREAK MAY BE POSSIBLE EARLY THIS EVENING AS THIS FIRST
BOUNDARY DISSIPATES AND ANOTHER COLD FRONT APPROACHES FROM THE
NORTH. GUIDANCE HAS BEEN INDICATING A LINE OF THUNDERSTORM
DEVELOPMENT OVER OUR CWA OR JUST TO THE NORTH AND TRACK SOUTH. THE
BEST TIMING FOR THIS LOOKS TO BE BETWEEN 0-3Z. WITH THE SUNSET AND
EARLIER STORMS...INSTABILITY WILL BE LACKING AS WELL AS LAPSE RATES
AND SHEAR DECREASING. BUT THERE IS QUITE A BIT OF LIFT ALOFT AND A
SURFACE BOUNDARY SO WILL BE KEEPING CHANCE OF THUNDER IN THE
FORECAST.

BEHIND THAT FRONT...PROBABLY WILL SEE A MOSTLY DRY DAY FOR WEDNESDAY
THROUGH WEDNESDAY EVENING OUTSIDE OF SOME POSSIBLE FOG DEVELOPMENT
AFTER THE FRONT/RAIN GOES THROUGH IN THE WARNING. A WARM MOIST
SOUTHWESTERLY FLOW ONCE AGAIN BUILDS IN FOR WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT WITH MODERATE INSTABILITY AND SHEAR FOR THIS TIME
FRAME BUT IMAGINE THESE THUNDERSTORMS WILL JUST BE POP UP AFTERNOON
HEATING TYPES AND NOT EXPECTING SEVERE AT THIS TIME.

GUIDANCE TEMPS FOR WED HAVE WARMED UP A FEW DEG OVER THE LAST FEW
DAYS AND FROM THE PREVIOUS FORECAST...ESPECIALLY THE NAM/MET
GUIDANCE. WITH JUST SOME SCT STRATOCU WED ALONG WITH SOUTHWESTERLY
RETURN FLOW THROUGH THE LOWER LEVELS OF THE ATMOSPHERE...A WARMER
TEMP FORECAST IS WARRANTED. THE ONLY CAVEAT WILL BE THE CLOUD
COVER...AS THE STRATOCU COULD HAVE HIGHER AREAL COVERAGE THAN
CURRENTLY FORECAST. GUIDANCE IS ALSO WARMER FOR THURSDAY BUT THERE
SHOULD BE MORE CLOUD COVER TO LIMIT THE TEMPS TO GET MUCH WARMER
THAN FORECAST VALUES FOR WED.

A DEEP SURFACE LOW STARTS TO DEVELOP NORTH OF THE GREAT LAKES ON
THURSDAY...EXTENDING A STRONG COLD FRONT SOUTH THROUGH THE MIDDLE OF
THE UNITED STATES. ANOTHER SURFACE WAVE DEVELOPS ALONG THIS FRONT
OVER THE MISSISSIPPI RIVER VALLEY. THIS FRONT WILL SLOWLY MAKE ITS
WAY NW TO SE ACROSS THE FORECAST AREA THROUGH 12Z ON SATURDAY. THIS
WILL BRING A HIGHER CHANCE OF SHOWERS AND THUNDERSTORMS AND WENT
LIKELY THUNDERSTORMS IN THE FORECAST AFTER 18Z BUT THE LINE OF
THUNDERSTORMS WITH THE FRONT WILL PROBABLY MOVE THROUGH AFTER 00Z.
SHEAR IS STRONG WITH THIS SYSTEM ALONG WITH PLENTY OF SURFACE AND
UPPER SUPPORT AND STRONG LOW-MID LEVEL LAPSE RATES. THE LIMITING
FACTOR WILL BE INSTABILITY. THINKING WE WILL BE ON THE DECAYING EDGE
OF A QLCS TYPE SYSTEM WITH POSSIBLY A FEW STRONG STORMS AHEAD OF IT.
SEVERE STORMS WITH LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE AND
THIS WILL NEED TO BE MONITORED.

BEHIND THE COLD FRONT...COOLER TEMPS RETURN FOR SAT WITH HIGHS IN
THE LOWER 60S AND LOWS SAT NIGHT IN THE UPPER 30S TO AROUND 40. A
STRONG HIGH PRESSURE AREA BUILDS ACROSS THE REGION KEEPING SAT/SUN
DRY WITH PLENTY OF SUN. TEMPS RETURN TO NORMAL ONCE AGAIN BY SUNDAY
AND BACK INTO THE LOWER 70S BY TUESDAY.

RIDGING ALOFT BUILDS IN ALOFT WITH THE STRONG SURFACE HIGH DEPARTING
TUE-THU...WITH DEEP LAYER SOUTHWEST FLOW RETURNING. CONTINUED THE
CHANCE OF SHOWERS AND THUNDERSTORMS BASICALLY MON-WED WITH JUST RAIN
CHANCES OVERNIGHT EACH NIGHT. LOOKS LIKE THE MAIN HAZARD WILL BE
DIURNALLY DRIVEN THUNDERSTORMS ALONG WEAK SURFACE BOUNDARIES...BUT
WILL NEED TO KEEP AN EYE ON THE GFS/DGEX HINTS AT SOME SORT OF MCS
SET UP FOR MONDAY. UNCERTAINTIES STILL EXIST AMONG GUIDANCE IN TERMS
OF TIMING SO THIS WILL ALSO NEED TO BE MONITORED AS WELL.

LN

&&

.AVIATION...
FOR 00Z TAFS...AN UPPER WAVE MOVING ACROSS THE AREA IS COMBINING WITH
A VERY UNSTABLE ATMOSPHERE TO PRODUCE SCT SHRA/TSRA. THE MAIN THREAT
WITH ANY TSRA WILL BE LARGE HAIL. THE SHRA/TSRA ACTIVITY WILL BEGIN
TO DECREASE IN AREAL COVERAGE AND INTENSITY BY MIDNIGHT WITH ALL
PCPN ENDING BY 12Z WEDNESDAY MRNG. MAINLY VFR CONDITIONS ARE EXPECTED
THRU THE FCST PERIOD...EXCEPT MVFR IN TSRA .

07

&&

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

$$

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



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