Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 210526 AAC
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1226 AM CDT THU AUG 21 2014

.UPDATE...
FOR 06Z TAFS

&&

.DISCUSSION...
/ISSUED 858 PM CDT WED AUG 20 2014/

MUCH OF THE CONVECTIVE COMPLEX THAT WAS CAUSING SEVERE WEATHER
EARLIER ACROSS S MIDDLE TN HAS WEAKENED OR HAS DISSIPATED ACROSS
DEKALB AND JACKSON COUNTIES IN AL. THE LOSS OF DAYTIME HEATING AND
THE DEVELOPING INVERSION HAS RELEGATED THE REMAINING CONVECTIVE
ACTIVITY TO PULSE LIKE IN NATURE. THERE IS A SLOW MOVING OUTFLOW
BOUNDARY THAT IS STILL PROPAGATING SOUTHWESTWARD FROM EARLIER
CONVECTION OVER MIDDLE TN. THE RESIDUAL PORTIONS OF THIS OUTFLOW ARE
CURRENTLY OVER MARSHALL AND BLOUNT COUNTIES WITH SOME REMNANTS
BARELY VISIBLE OVER E MADISON COUNTY VIA WSR-88D. WILL SHIFT THE
THUNDERSTORM CHANCES TO MORE ISOLATED STORMS ESPECIALLY OVER NE AL
AND S MIDDLE TN. THIS IS MAINLY DUE TO THE PROPAGATION OF OUTFLOW
BOUNDARIES APPROACHING FROM FURTHER NORTH (AND THE ONE ALREADY
MENTIONED) PROVIDING ENOUGH LIFT TO TRIGGER ISOLATED THUNDERSTORMS
WITHIN THIS VERY MOIST AND WARM MARITIME TROPICAL AIRMASS.

THE TEMPERATURE FORECAST IS CHALLENGING TONIGHT AS THE RAIN COOLED
PORTION OF THE AREA (NE AL/S MIDDLE TN) IS STARTING OFF MUCH COOLER
THAN THE REST OF THE AREA. THUS, A GRADIENT OF 5-7 DEGREES IN
OVERNIGHT LOWS IS LIKELY BETWEEN AREAS THAT RECEIVED RAIN EARLIER
THIS EVENING AND THOSE THAT DID NOT. DEWPOINT TEMPERATURE FORECAST IS
SIMILAR TO THE TEMPERATURE FORECAST IN THE GRADIENT BUT ADDITIONAL
ADJUSTMENTS WERE NEEDED FURTHER WEST WHERE DEWPOINTS ARE ALREADY
STARTING THE NIGHT NEAR 73-74 DEGREES.

OTHERWISE, MADE ADJUSTMENTS TO THE SKY COVER FORECAST TO ACCOUNT FOR
THE DEBRIS AC/CU/CIRRUS THAT MAY BE AROUND TONIGHT FROM EARLIER
THUNDERSTORM ACTIVITY. ADDED PATCHY FOG AREAWIDE, BUT IT WILL LIKELY
BE MORE DENSE IN NATURE OVER THE PAINT ROCK RIVER, ELK RIVER,
GUNTERSVILLE LAKE, I-59 CORRIDOR, AND TENNESSEE RIVER (JACKSON
COUNTY) AREAS. NE AL/S MIDDLE TN WHERE THUNDERSTORMS DROPPED HEAVY
RAINFALL.

SL.77

&&

.AVIATION...
FOR 06Z TAFS...
VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR MOST OF THE NEXT 24 HOURS.
FOG FORMATION IS POSSIBLE BTWN 10-13Z WHICH MAY RESULT IN A DROP TO
MVFR AT BOTH TAF LOCATIONS. LOWER CATS TO IFR ARE POSSIBLE OVER NE
AL/S MIDDLE TN (NEAR K4A6, K4A9, KFYM, KBGF) UNTIL 13Z.

SL.77

&&

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

$$

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



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