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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 111112
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
710 AM EDT TUE MAR 11 2014

.SYNOPSIS...
-- Changed Discussion --
SOUTHERLY FLOW WILL RESULT IN UNSEASONABLY WARM CONDITIONS TODAY.
MOISTURE WILL OVERSPREAD THE AREA TONIGHT AHEAD OF A SOUTHERN STREAM
SYSTEM MOVING NORTHEAST FROM THE GULF OF MEXICO INTO THE SOUTHEAST
US. A COLD FRONT WILL THEN CROSS THE STATE WEDNESDAY AFTERNOON AND
EVENING...BRINGING MUCH COLDER AIR THURSDAY INTO EARLY FRIDAY.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM TUESDAY...

TODAY...CENTRAL NC WILL SIT UNDER ZONAL FLOW ALOFT DOWNSTREAM OF A
SOUTHERN STREAM CLOSED MID-UPPER LOW FORECAST TO MIGRATE AND
DEAMPLIFY FROM THE RIO GRANDE TO THE CENTRAL GULF COAST STATES. THE
WESTERLY FLOW AND ASSOCIATED DOWNSLOPE COMPONENT WILL MAINTAIN LEE
SURFACE TROUGHING ACROSS THE PIEDMONT OF THE CAROLINAS...WHILE
AIDING A LIGHT SOUTHERLY BREEZE  IN BOOSTING TEMPERATURES INTO THE
MID TO UPPER 70S.

TONIGHT...EXPECT A RAPID INCREASE IN CLOUD COVER THIS EVENING WITH
WAA SHOWERS OVERSPREADING THE AREA FROM THE SOUTHWEST LATE TONIGHT
AND THROUGH WEDNESDAY MORNING(09 TO 15Z) WITHIN THE 40-50KT WARM
CONVEYOR BELT FEED ASSOCIATED WITH THE AFOREMENTIONED SOUTHERN
STREAM SYSTEM EXITING SOUTHEAST COAST WEDNESDAY MORNING. MILD
OVERNIGHT LOWS IN THE MID TO UPPER 60S.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM TUESDAY...

THERE WILL LIKELY BE A GOOD 6-9HR LULL IN PRECIP/POPS BETWEEN THE
WAA SHOWERS EXITING OFFSHORE DURING THE LATE MORNING(15-16Z) AND THE
ARRIVAL THE FRONTAL CONVECTIVE LINE FROM THE WEST LATE
AFTERNOON(~21Z). WITH THE EXTRA HOUR OF DAYLIGHT AND INCREASING SUN
ANGLE THIS SHOULD BE AMPLE BREAKS IN THE CLOUD COVER TO ALLOW
AFTERNOON TEMPERATURES TO WARM UP INTO THE LOWER TO MID
70S...WARMEST ACROSS THE SE. THE NAM IS THE MOST UNSTABLE DURING THE
AFTERNOON...DEPICTING WEAK INSTABILITY OF 200 TO 500 J/KG ACROSS THE
COASTAL PLAINS...WHERE HEATING IS EXPECTED TO BE STRONGEST. IF WEAK
INSTABILITY DOES DEVELOP...DESPITE MID-LEVEL DRY SLOT OVERTAKING THE
AREA...THE WEAK BUOYANCY SHOULD HELP TO MAINTAIN THE CONVECTIVE LINE
THROUGH THE AREA BETWEEN 21-03Z. HOWEVER...IF WE ARE MORE STABLE AS
THE GFS SUGGESTS...COUPLED WITH THE DRYING ALOFT...THE FRONTAL
CONVECTIVE LINE COULD DRY UP ALL TOGETHER. WILL LEAVE A SLIGHT
CHANCE OF THUNDER ACROSS THE EAST...BUT SEVERE THREAT IS NON-
EXISTENT.

SHOWERS SHOULD EXIT THE AREA DURING THE EVENING WITH STRONG CAA
CLEARING OVERNIGHT. LOWS WEDNESDAY NIGHT RANGING FROM THE UPPER 20
NW TO MID 30S SE.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...

AFTER SEVERAL DAYS OF SPRING-LIKE TEMPS...DEEP UPPER TROUGHING OVER
THE EAST COAST ON THURSDAY WILL LEAD TO AN ABRUPT CHANGE BACK TO
WINTER-LIKE TEMPS...AS HIGHS WILL ONLY BE IN THE 40S...A GOOD 15-20
DEGREES BELOW NORMAL. IN ADDITION...A STRONG GRADIENT BETWEEN THE
DEPARTING SURFACE LOW AND THE HIGH BUILDING IN WILL RESULT IN BREEZY
CONDITIONS...MAKING IT FEEL EVEN COLDER. OVERNIGHT LOWS WILL FALL
INTO THE MID 20S. THESE WELL BELOW NORMAL TEMPS WILL BE SHORT LIVED
THOUGH AS WEAK SHORTWAVE RIDGING BUILDS EAST OVER THE AREA AND THE
SURFACE HIGH SLIPS OFFSHORE (SETTING UP RETURN FLOW) ON FRIDAY. ALL
OF THIS WILL RESULT IN TEMPS MODERATING INTO THE MID/UPPER 50S.

THE NEXT SHORT WAVE TROUGH/SURFACE FRONT WILL APPROACH/CROSS THE
AREA SATURDAY INTO SUNDAY...HOWEVER THERE CONTINUES TO BE
DISAGREEMENT AMONG THE MODELS ON OUR PRECIP CHANCES. THE GFS
CONTINUES TO BE THE WETTER MODEL AS IT IS MORE AMPLIFIED WITH THE
UPPER WAVE AND TAPS INTO THE GULF MOISTURE MORE. THE ECMWF STILL IS
VIRTUALLY DRY. WILL MAINTAIN THE CURRENT FORECAST THINKING UNTIL
MODELS COME INTO BETTER AGREEMENT...THUS HOLDING PRECIP CHANCES
DOWN...WITH ONLY AN INCREASE IN CLOUD COVER. CONTINUED LOW LEVEL
SOUTHERLY FLOW WILL RESULT IN MORE AIR MASS MODIFICATION...WITH
HIGHS EXPECTED TO RISE INTO THE MID 60S ON SATURDAY. BRIEF NORTHERLY
WINDS BEHIND THE FRONT EARLY ON SUNDAY SHOULD RESULT IN SLIGHTLY
LOWER TEMPS...GENERALLY MORE IN THE WAY OF LOWER 60S.

CONFIDENCE DECREASES EVEN FURTHER FOR VERY END OF THE WEEKEND AND
INTO EARLY NEXT WEEK...BUT THE GENERAL CONSENSUS IS THAT A NORTHERN
STREAM TROUGH WILL DIG INTO THE SOUTHEAST...WITH YET ANOTHER COASTAL
LOW IMPACTING THE REGION AS SOUTHERN STREAM ENERGY MOVES EAST.
HOWEVER...THERE IS LARGE MODEL SPREAD...WITH THE GFS DIGGING THE
NORTHERN STREAM LOW INTO THE CENTRAL/SOUTHERN GULF...SUPPRESSING THE
STORM TO THE SOUTH AND EAST OF CENTRAL NC AS THE RESULTANT SURFACE
LOW TRACKS WELL OFFSHORE. THE ECMWF IS NOT AS SUPPRESSED AND THE
RESULTANT SURFACE LOW TRACKS CLOSER TO THE COAST...THUS SPREADING
PRECIP INTO THE REGION. FOR NOW WILL SHOW INCREASING PRECIP CHANCES
LATE SUNDAY INTO MONDAY...WITH NEAR NORMAL TEMPS.

&&

.AVIATION /12Z TUESDAY THROUGH FRIDAY/...
-- Changed Discussion --
AS OF 700 AM MONDAY...

24 HOUR TAF PERIOD: HIGH CONFIDENCE OF VFR CONDITIONS THROUGH 06Z
WEDNESDAY.  EXPECT  SOUTHWESTERLY SURFACE WINDS 5-10 KTS WITH MAYBE
A FEW GUSTS IN THE AFTERNOON BUT NOT SIGNIFICANT ENOUGH TO INCLUDE
IN THE TAFS AT THIS TIME.

RAIN AND IFR TO MVFR RESTRICTIONS ARE EXPECTED TO SPREAD BACK INTO
THE AREA LATE TUESDAY NIGHT AND INTO WEDNESDAY...AS A SOUTHERN
STREAM SYSTEM FROM GULF OF MEXICO MOVES INTO THE SOUTHEAST. A STRONG
COLD FRONT WILL THEN CROSS THE AREA FROM THE WEST LATE WEDNESDAY
AFTERNOON/EVENING WITH A LINE OF CONVECTION EXPECTED ALONG THE
FRONT. STRONG DRY COLD AIR ADVECTION IN THE WAKE OF THE SYSTEM WILL
BRING A RETURN TO VFR CONDITIONS WEDNESDAY EVENING/NIGHT.  GUSTY SW
WINDS WILL DEVELOP WEDNESDAY AFTERNOON AHEAD AND WILL BECOME NWLY
WED NIGHT INTO THUR BEHIND THE COLD FRONT...WHICH COULD RESULT IN
CROSSWIND IMPACTS FOR RUNWAYS.
-- End Changed Discussion --

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...MWS
NEAR TERM...CBL
SHORT TERM...CBL
LONG TERM...KRD
AVIATION...CBL