Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 042331 AAA
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
631 PM CDT TUE AUG 4 2015

.UPDATE...
FOR 00Z TAFS

&&

.DISCUSSION...
/ISSUED 232 PM CDT TUE AUG 4 2015/
WEAK HIGH PRESSURE REMAINS AT THE SURFACE THIS AFTERNOON WITH A
DEVELOPING SHORTWAVE EVIDENT OVER THE MIDWEST. THIS WILL BE THE MAIN
FEATURE FOR SHOWER/THUNDERSTORM DEVELOPMENT FOR WED-THU. BUT FOR
NOW...A WEAK CONVERGENCE BOUNDARY AND INCREASED
INSTABILITY...WILL LEAD TO ISOLATED SHOWER/THUNDERSTORM DEVELOPMENT
THROUGH THE DAYLIGHT HOURS. CLOUDS WILL CONTINUE TO INCREASE
OVERNIGHT WITH THE APPROACH OF THE SHORTWAVE.

THE RIDGE CONTINUES TO BREAK DOWN OFF TO THE WEST OVERNIGHT WITH A
SHORTWAVE DEEPENING OVER THE MO VALLEY WEDNESDAY AFTERNOON. SHOWERS
AND THUNDERSTORMS ASSOCIATED WITH THAT WAVE WILL TRACK TO THE
SOUTHEAST TOWARDS THE LOCAL AREA OVERNIGHT WED NIGHT. YESTERDAY
THERE WAS A HINT AT SOME ADDITIONAL RAINFALL PUSHING NORTH FROM A
SEA BREEZE SORT OF FRONT BUT GUIDANCE HAS REALLY BACKED OFF ON THAT
AND KEPT IT ALL WELL SOUTH OF THE AREA. THE PROGRESSION OF THE
SHORTWAVE IS ALSO A BIT SLOWER SO MUCH OF THE DAY ON WED MAY END UP
DRY. THERE WILL PROBABLY BE A FEW INSTABILITY BASED THUNDERSTORMS
DURING THE DAY BUT THE BULK OF THE RAINFALL WILL BEGIN AFTER 00-06Z
THURSDAY. EVEN WITH THE CHANCE OF SHOWERS/STORMS...MAINTAINED THE
HIGHS IN THE LOWER TO MIDDLE 90S THANKS TO A WARM SOUTHERLY FLOW AND
SOME BREAKS IN THE CLOUDS.

HIGHER CONFIDENCE IN STRONGER THUNDERSTORMS LOOKS TO BE THURSDAY AND
GUIDANCE HAS BEEN CONSISTENT WITH FAIRLY WIDESPREAD RAINFALL. THE
UPPER WAVE WILL BE MOVING THROUGH BY THURSDAY NIGHT AND PASSING OFF
TO THE EAST AS WELL AS A VERY WEAK FRONTAL/CONVERGENCE BOUNDARY
SETTING UP JUST TO THE NORTH. A LOW LEVEL JET DEVELOPS AND MOVES
INTO THE AREA THURSDAY AFTERNOON WHICH HELPS INCREASE 0-1KM SHEAR TO
15-20KT AND 30-40KT OF 0-6KM SHEAR WHICH IS FAIRLY HIGH FOR THIS
TIME OF YEAR. THU MORNING SOUNDINGS ARE LOOKING MORE LIKE HEAVY
RAINFALL BUT SOME DRY AIR STARTS TO MIX IN AT THE LOW LEVELS AND MID
LEVELS BY THU AFTERNOON. COUPLE THAT WITH CAPE VALUES AROUND 2000
J/KG OR MORE...AND THERE IS A GOOD CHANCE SOME STORMS WILL BE STRONG
AND A COUPLE POSSIBLY SEVERE WITH THE HIGHEST THREAT BEING DAMAGING
WINDS.

THE WAVE PASSES WELL TO THE EAST ON FRIDAY BUT WITH THE SURFACE
BOUNDARY STILL SLOWLY SINKING TO THE SOUTH...GOING TO BE ENOUGH LIFT
AND INSTABILITY/SHEAR REMAINING TO KEEP CHANCE SHOWERS/THUNDERSTORMS
IN THE FORECAST FOR FRI AND THEN TAPERING OFF FRI NIGHT.  THE GOOD
NEWS IN ALL OF THIS IS THAT TEMPS BOTH THU/FRI WILL ONLY GET INTO
THE MIDDLE TO UPPER 80S WHICH IS COOLER THAN THE PREVIOUS FEW DAYS.

THE UPPER RIDGE MAKES ITS RETURN ON SATURDAY AND PRESSES IN FROM THE
WEST WITH WEAK HIGH PRESSURE AT THE SURFACE THROUGH SUNDAY. SEEMS TO
BE ENOUGH SUBSIDENCE AND DRIER AIR ALOFT TO KEEP THE AREA DRY.
CANNOT RULE OUT A SHOWER OR TWO SUNDAY AFTERNOON BUT NOT CONFIDENT
ENOUGH TO INCLUDE IN THE FORECAST. ANOTHER TROUGH AND UNSETTLED
WEATHER WILL IMPACT THE REGION AGAIN MON-TUE WITH HIGHS FOR THE
BEGINNING OF THE WEEK BACK INTO THE LOWER TO MIDDLE 90S.

LN

&&

.AVIATION...
FOR 00Z TAFS...

VFR CONDITIONS ARE EXPECTED THROUGH THE NEXT 24 HOURS AT THE KMSL AND
KHSV TERMINALS. THE HIGH PRESSURE IN PLACE WILL WEAKEN WEDNESDAY
MORNING...WITH THE CHANCE OF SHOWERS AND THUNDERSTORMS INCREASING
BEYOND THE PERIOD.

73

&&

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

$$

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



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