Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 182346 AAA
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
646 PM CDT THU SEP 18 2014

.UPDATE...
FOR 00Z TAFS

&&

.DISCUSSION...
/ISSUED 112 PM CDT THU SEP 18 2014/
NW FLOW CAN BE A HUMBLING EXPERIENCE IN FORECASTING, AND TODAY IS NO
DIFFERENT. AFTER A NARROW OVERNIGHT BAND OF SHOWERS AND A BREAK THIS
MORNING, ANOTHER WEAK SHORTWAVE AND CLUSTER OF SHRA/TSRA IS MOVING
TOWARD US FROM WESTERN TN. CONVECTION IS ELEVATED AND APPEAR BASED
NEAR 850 MB PER OBSERVATIONS OF CLOUD BASES. THE SHORT TERM
FORECASTER HAS ALREADY UPDATED FOR THIS, AND WE WILL CARRY THESE POPS
ACROSS OUR CENTRAL AND WESTERN COUNTIES INTO THIS EVENING. THIS
CONVECTION SHOULD SHIFT TO OUR S BEFORE 06Z. 5H FLOW BECOMES
NORTHERLY ON FRIDAY ACROSS THE TN VALLEY IN RESPONSE TO THE UPPER
RIDGE AMPLIFYING A BIT OVER THE CENTRAL PLAINS AND OZARK PLATEAU
REGIONS. THE SURFACE RIDGE OVER THE GREAT LAKES AND OH VALLEY WILL
ALSO SHIFT INTO THE MID ATLANTIC AND WITH ITS SRN EXTENSION INTO THE
DEEP SOUTH ENABLING MORE SUBSIDENCE AND LESS CLOUDS OVER THE WEEKEND.
8H TEMPS IN THE M10S CELCIUS SHOULD ALLOW FOR HIGHS TO REMAIN IN THE
L-M80S FAHRENHEIT THRU D3 (SUNDAY).

AS HAS BEEN ADVERTISED FOR A FEW DAYS NOW, A STRONGER MID/UPPER JET
AND SHORTWAVE WILL SWING INTO THE GREAT LAKES, ENABLING A LARGE
SCALE COLD FRONT TO PUSH THRU MUCH OF THE EASTERN AND SOUTHERN U.S.
THIS ARRIVES LATE SUNDAY AFTERNOON AND EARLY EVENING IN OUR AREA.
SFC-BASED CAPE/CONVECTIVE INSTABILITY IS PROGGED TO BE A BIT HIGHER
THAN PREVIOUS RUNS WITH DEW POINTS CLIMBING BACK INTO THE 60S. WILL
MAINTAIN A TS CHC AS A RESULT WITH A RAPID CLEARING AND DRYING
INDICATED ON MONDAY. DEW POINTS BY MONDAY AFTERNOON WILL FALL INTO
THE 40S. EASTERLY FLOW WILL DEVELOP BY D5-6 (TUESDAY-WEDNESDAY) ALONG
THE SOUTHERN PORTION OF THE LARGE HIGH PRESSURE SYSTEM COVERING THE
EASTERN CONUS AND SERN CANADA. THIS WILL BRING A TEMPORARY INCREASE
IN LOW LEVEL MOISTURE LEADING TO POSSIBLE VALLEY FOG EVENTS EARLY
NEXT WEEK. THEN A CAD SITUATION EVOLVES WITH N-NELY FLOW ALONG THE
EASTERN SLOPES OF THE PIEDMONT D7 AND BEYOND. NO RAIN IS FORESEEN
THRU THIS PD.

AK

&&

.AVIATION...
FOR 00Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD
UNTIL ~07/08Z WHEN MVFR VIS DUE TO FOG IS POSSIBLE. VFR CONDITIONS
WILL RETURN WHEN FOG DISSIPATES ~13Z. LIGHT E/ESE WINDS ARE EXPECTED
THROUGHOUT THE DAY ON FRIDAY.

JMS

&&

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

$$

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



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