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000
FXUS64 KHUN 171402 AAB
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
902 AM CDT MON MAR 17 2014

.UPDATE...
TO ADD DRIZZLE TO TODAY`S FORECAST AND INCREASE SKY COVERAGE TO NEAR
100 PERCENT FOR THE AFTERNOON.
&&

.DISCUSSION...
WATER VAPOR IMAGERY IS SHOWING A VORTICITY AXIS SHEARING NEWD THRU
THE TN VALLEY THIS MORNING. AT THE SURFACE, LOW PRESSURE WAS
SITUATED ALONG THE AL/GA STATELINE SW OF ATL. A STRONG WEDGE FRONT
WAS WORKING ITS WAY SW INTO NRN GA AND WE`LL BE MONITORING IT`S
PROGRESS TODAY AS IT MAY HAVE SOME EFFECT IN OUR EASTERN COUNTIES BY
TONIGHT.

RADARS SHOW A FEW REMAINING -SHRA MOVING ACROSS NE AL. LOW CLOUDS
AND PATCHY -DZ ARE OCCURRING OVER THE REST OF THE AREA. TEMPS HAVE
DIPPED TO 30-32F IN SRN TN, BUT TEMPS SHOULD WARM BACK ABOVE FREEZING
SHORTLY. WE HAVE ADDED -DZ TO THE FORECAST FOR TODAY, AND CANNOT RULE
OUT ADDITIONAL -SHRA AS THE SHEAR ZONE DRIFTS ACROSS THE AREA.

AK

&&

.AVIATION...
/ISSUED 717 AM CDT MON MAR 17 2014/
FOR 12Z TAFS...LOW STRATUS/MIST AND -DZ WILL CONTINUE ACROSS THE AREA
THIS MORNING IN THE NW QUADRANT OF A WEAKENING SFC LOW ACROSS NW
GEORGIA. ALTHOUGH THREAT FOR -DZ AND REDUCED VSBY WILL BE HIGHEST AT
HSV...IFR CIGS WILL IMPACT THE HSV/MSL TERMINALS THRU 16Z -- WITH THE
DECK EXPECTED TO LIFT TO 1500 FT BY EARLY AFTN. WILL CONTINUE TO
FORECAST CIGS TO LIFT TO 2500-4000 FT FROM LATE AFTN THRU THIS
EVENING BUT THIS MAY BE OPTIMISTIC. IF ANY SCATTERING/LIFTING
OCCURS...IT WILL BE TEMPORARY AS WINDS DIMINISH SETTING THE STAGE
FOR IFR STRATUS AND MIST ONCE AGAIN. PATCHY -DZ MAY ALSO REDEVELOP
TOWARD END OF PERIOD AT HSV AS A BACKDOOR FRONT MOVES THRU REGION
FROM THE EAST -- SHIFTING FLOW AROUND TO THE SSE BTWN 18/09-12Z.

70/DD

&&

.PREV DISCUSSION...
/ISSUED 320 AM CDT MON MAR 17 2014/
WATER VAPOR IMAGERY AND RAP H5 ANALYSIS INDICATED AN UPPER TROF
STRETCHED FROM THE ARKLAMISS SOUTHWESTWARD INTO DEEP SOUTH TEXAS THIS
MORNING, WITH THE SUBTROPICAL JET PUMPING MOISTURE NORTHEASTWARD ACROSS
MUCH OF THE EASTERN SEABOARD. A BUILDING RIDGE WAS ANALYZED OFFSHORE
OF SOCAL/BAJA PENINSULA, ENCOMPASSING MUCH OF THE INTERMOUNTAIN
WEST. ANOTHER UPPER LOW WAS BEGINNING TO DEEPEN OVER THE PACNW, WITH
YET ANOTHER UPPER LEVEL LOW EXITING THE FAR EASTERN CANADIAN
PROVINCES THIS MORNING. AT THE SFC, A WEAK LOW WAS DIRECTLY OVER OUR
EASTERN ZONES, WITH A COLD FRONT DRAPED SOUTHWESTWARD BACK INTO THE
WRN GOMEX. A TIGHTENING PRESSURE GRADIENT TO THE W/NW WAS NOTED AS
HIGH PRESSURE WAS BUILDING SOUTHEASTWARD FROM THE CENTRAL PLAINS. AS
A RESULT, REGIONAL METARS REPORTED GUSTY N/NW WINDS AS FAR WESTWARD
AS CENTRAL AR, WITH THE BACK EDGE OF THE LOW CLOUD COVER NOTED NOT
FAR FROM THERE. 3AM TEMPS LOCALLY RANGE FROM THE UPPER 30S IN NW AL
TO THE LOWER 50S IN NE AL.

POST-FROPA -RA IS EXPECTED TODAY WITH CAA KEEPING AFTN HIGH TEMPS IN
THE 45-50 DEGREE RANGE IN MANY LOCATIONS (AND THAT`S PROBABLY PRETTY
GENEROUS). THE ONLY EXCEPTION TO THIS THINKING IS FAR NE AL WHERE IT
WILL TAKE LONGER FOR THE COLDER AIR TO ARRIVE, SO TEMPS BETWEEN 50
AND 55 ARE REASONABLE THERE. THE CLOUDS WILL HANG AROUND THROUGH LATE
THIS AFTERNOON WHEN PARTIAL CLEARING IS EXPECTED IN NW AL AS THE BACK
EDGE OF THE CLOUDS SLOWLY INCHES EASTWARD. THE CLEARING LINE WON`T
MAKE IT ACROSS THE ENTIRE CWFA UNTIL LATE TUESDAY AFTERNOON/EVENING.

THE UPPER LOW CURRENTLY OVER DEEP SOUTH TX WILL MEANDER EASTWARD
ALONG THE NRN GOMEX, ENDING UP OFFSHORE OF THE CAROLINAS BY 12Z
TUESDAY. BY THIS TIME, THE UPPER LOW DEEPENING OVER THE PACNW WILL
INDUCE SFC CYCLOGENESIS OVER THE CENTRAL PLAINS. THIS WILL ALLOW A
QUICKLY BUILDING RIDGE OF HIGH PRESSURE ALOFT OVER THE MID-MS RIVER
VALLEY TO COMBINE WITH STRENGTHENING RETURN-FLOW LOCALLY TO HELP
AFTN HIGHS TOP OUT IN THE 60-65 DEGREE RANGE TOMORROW. SOUTHERLY
WINDS WILL GUST UP TO 20KTS TOMORROW AFTN AS WELL.

AS THE AFOREMENTIONED SFC LOW EJECTS NORTHEAST TOWARD THE GREAT
LAKES, A WEAK COLD FRONT WILL CLIP THE AREA TUESDAY NIGHT INTO
WEDNESDAY. THE BETTER FORCING/LIFT WILL REMAIN WELL NORTH OF THE TN
VALLEY CLOSER TO THE UPPER/SFC LOW, BUT MODELS ARE PAINTING LIGHT QPF
ACROSS THE ERN ZONES BY 12Z WED WITH THE FROPA ITSELF. FOR NOW, AM
NOT TOO IMPRESSED WITH THIS SCENARIO WITH THE LIMITED MOISTURE
(DEWPOINTS IN THE UPPER 30S TO LOWER 40S)IN THE TN VALLEY, SO FOR
NOW, WILL KEEP 14-POPS IN PLACE DURING THIS TIME TO SHOW UNCERTAINTY.

OTHERWISE, ZONAL FLOW ALOFT WILL RULE THE LATTER HALF OF THE WEEK,
WITH AFTN HIGHS IN THE UPPER 60S TO LOWER 70S BY FRIDAY. MORNING LOWS
WILL DIP INTO THE UPPER 30S THURSDAY MORNING, BUT A GRADUAL WARMUP
BACK INTO THE UPPER 40S/LOWER 50S IS EXPECTED BY SATURDAY AS ANOTHER
STRONGER COLD FRONT APPROACHES FROM THE NW. AS A DISTURBANCE QUICKLY
TRAVERSES THE NRN PLAINS/SRN GREAT LAKES REGION, A COLD FRONT WILL BE
JUST NORTHWEST OF THE AREA BY 12Z SAT. HAVE INCREASED POPS FOR
SATURDAY MORNING/AFTN, BUT RAIN WILL END QUICKLY FROM WEST TO EAST BY
SATURDAY EVENING POST-FROPA AS HIGH PRESSURE BUILDS SOUTHWARD FROM
THE HIGH PLAINS.

12

&&

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

$$

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