Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 291106
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
606 AM CDT FRI MAY 29 2015

.UPDATE...
FOR 12Z TAFS

&&

.DISCUSSION...
/ISSUED 244 AM CDT FRI MAY 29 2015/
THE DAY IS SHAPING UP TO START OFF DRY WITH TEMPS ONLY DROPPING
OVERNIGHT INTO THE MIDDLE 60S AND WILL REBOUND ONCE AGAIN INTO THE
LOWER 80S. NOT MUCH CHANGE IN FORECAST THINKING FROM PREVIOUS SHIFTS
FOR TODAY. CONTINUED SOUTH-SOUTHWESTERLY FLOW THROUGH THE COLUMN
REMAINS EVIDENT AROUND AN BROAD OFFSHORE RIDGE TO THE EAST. THERE
ALSO LOOKS TO BE SOME SORT OF BACKDOOR FRONT/WAVE PUSHING IN FOR THE
AFTERNOON TODAY. THAT COMBINED WITH A WEAK SHORTWAVE ALOFT WILL HELP
BE THE FOCUS FOR SHOWERS/THUNDERSTORMS. PW VALUES REMAIN ABOVE 1.5IN
AS WELL AS DEW POINTS HOLDING STRONG IN THE MIDDLE TO UPPER 60S
WHICH WILL HELP THE WEAK LIFT INITIATE THE SHOWERS/THUNDERSTORMS.
THEY LOOK TO BE LESS IN COVERAGE THAN PREVIOUS AFTERNOONS SO WILL
CONTINUE CHANCE POPS. INSTABILITY INCREASES AS USUAL THIS AFTERNOON
BUT SHEAR ONCE AGAIN LOOKS TO BE NONEXISTENT. SOUNDINGS CONTINUE TO
INDICATE THAT THE HIGHEST THREAT WILL BE LOCALLY HEAVY RAINFALL WITH
A FEW STORMS PRODUCING SMALL HAIL AND GUSTY WINDS. SHOWERS THEN
TAPER OFF AFTER SUNSET THIS EVENING.

FOR SATURDAY...AN UPPER TROUGH MOVES TO THE EAST AND WEAKENS AND
OPENS UP AS IT APPROACHES THE REGION. A SURFACE COLD FRONT
ASSOCIATED WITH THIS UPPER FEATURE WILL STRETCH FROM NORTH OF THE
GREAT LAKES DOWN THROUGH SOUTHEAST TEXAS. THE FRONT BASICALLY WASHES
OUT OVER OR TO THE NORTHWEST OF THE AREA WITH ONLY A BRIEF SHIFT TO
NORTHWEST WINDS EARLY IN THE DAY BEFORE THEY RETURN BACK TO A
SOUTHERLY FLOW BY SUNDAY AFTERNOON. THE HIGHEST CHANCES FOR
SHOWERS/THUNDERSTORMS WITH THESE SYSTEMS WILL ONCE AGAIN BE SATURDAY
AFTERNOON AND MOSTLY TO THE NORTHWEST...CLOSER TO THE LIFT AND
TAPERING OFF AFTER SUNSET. SUNDAY HAS A HIGHER CHANCE OF SHOWERS AND
THUNDERSTORMS AND WILL CONTINUE THE LIKELY POPS. ONCE AGAIN...PLENTY
OF INSTABILITY EXISTS BUT WITH LITTLE SHEAR...DO NOT THINK ANY
STORMS WILL BE SEVERE. MORE DRY AIR EXISTS THROUGH THE COLUMN ON
SUNDAY SO ANY STRONG STORMS THAT DO DEVELOP COULD PRODUCE STRONG
WIND GUSTS.

IN TERMS OF MODEL DIFFERENCES FOR THE WEEKEND...THE GFS KEEPS THE
UPPER TROUGH A LITTLE STRONGER WITH SURFACE WAVES RUNNING ALONG THE
STALLED FRONTAL BOUNDARY. THIS IS IN COMPARISON TO THE ECMWF/NAM
WHICH ARE A BIT WEAKER OVERALL WITH THE UPPER AND SURFACE WAVES. THE
GFS SEEMS LIKE AN OUTLIER IN THIS SITUATION SO COVERAGE/STRENGTH OF
THE SHOWERS/THUNDERSTORMS MAY BE LESS THAN CURRENTLY FORECAST AND
WILL NEED TO CONTINUED TO BE MONITORED.

THE UPPER TROUGH PREVIOUSLY MENTIONED CUTS OFF A LOW OVER THE
SOUTHEAST HELPING TO PROVIDE UPPER LEVEL SUPPORT FOR SHOWERS THROUGH
THE WEEK NEXT WEEK. THE OFFSHORE RIDGE REMAINS STRONG DURING THIS
TIME AND WILL HELP FEED A CONTINUED STREAM OF MOIST AIR UP FROM THE
SOUTH. WITH SUCH A MESSY SUMMER LIKE SYSTEM...IT IS HARD TO
DISTINGUISH MUCH IN TERMS OF TIMING AND COVERAGE OF THE AFTERNOON
SHOWERS AND THUNDERSTORMS THIS FAR OUT. HIGH PW VALUES AND DEW
POINTS IN THE UPPER 60S WILL KEEP PLENTY OF MOISTURE THROUGH THE
WEEK SO ANY LIFT/INSTABILITY WILL HELP INITIATE SHOWERS AND
AFTERNOON THUNDERSTORMS. THIS WILL KEEP THE CHANCE OF THUNDERSTORMS
IN THE FORECAST EACH AFTERNOON THROUGH THE WORK WEEK. A SLIGHT
CHANCE OF SHOWERS/THUNDERSTORMS EXIST EACH NIGHT WITH LINGERING
DAYTIME ACTIVITY AND LIFT.

HIGHS GENERALLY WILL BE IN THE LOWER TO MID 80S THROUGH NEXT WEEK
WITH LOWS IN THE MIDDLE 60S...ALL NEAR NORMAL VALUES.

LN

&&

.AVIATION...
FOR 12Z TAFS...MAINLY MVFR CEILINGS WITH OCCASIONAL IFR AT KMSL THRU
18Z...WITH VFR CONDITIONS AFTER 18Z (EXCEPT MVFR IN TSRA). AS FOR
KHSV...WILL LIKELY STAY VFR THIS MRNG AND AFTN...EXCEPT MVFR IN TSRA.
WITH DAYTIME HEATING AND PLENTY OF LOW LEVEL MOISTURE...EXPECT SCT
TSRA BETWEEN 18Z AND 00Z FOR BOTH TAF SITES. AFTER 00Z EXPECT MAINLY
VFR CONDITIONS.

07

&&

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

$$

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


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