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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 231042
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
642 AM EDT THU MAY 23 2013

.SYNOPSIS...
A TROUGH ALOFT AND ACCOMPANYING PRE-FRONTAL SURFACE PRESSURE TROUGH
WILL SETTLE INTO CENTRAL NC TODAY...FOLLOWED BY THE PASSAGE OF A
COLD FRONT TONIGHT. CANADIAN HIGH PRESSURE WILL THEN EXPAND ACROSS
OUR REGION THROUGH THE HOLIDAY WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 315 AM THURSDAY...

TODAY: AT THE BASE OF AN UPPER LOW MIGRATING THROUGH THE LOWER GREAT
LAKES...A NEUTRALLY-TILTED MID-UPPER TROUGH AXIS - AND ASSOCIATED
20-30 METER HEIGHT FALLS - WILL PIVOT EASTWARD INTO CENTRAL NC
TODAY. MEANWHILE AT THE SURFACE...NWP GUIDANCE SUGGESTS A PRONOUNCED
PRE-FRONTAL TROUGH OVER WESTERN GA THIS MORNING WILL DEVELOP
EASTWARD INTO THE WESTERN CAROLINAS THIS AFTERNOON...WHILE LEFT-OVER
OUTFLOW FROM ONGOING CONVECTION OVER THE PIEDMONT WILL ALSO SERVE AS
A POSSIBLE FOCUS...WITH DIURNAL HEATING. THIS ONGOING CONVECTION
SHOULD CONTINUE TO DIMINISH IN COVERAGE AND INTENSITY AS IT EDGES
SLOWLY EASTWARD INTO AN INCREASINGLY STABLE/NOCTURNALLY-COOLED AIR
MASS OVER CENTRAL NC.

SCATTERED TO NUMEROUS SHOWERS AND STORMS WILL CONSEQUENTLY LIKELY
INITIATE INVOF BOTH BOUNDARIES...ONE OVER THE EASTERN PIEDMONT/
SANDHILLS...AND THE OTHER OF HIGHER CONFIDENCE/ PREDICTABILITY OVER
THE FOOTHILLS...WITH SOME TERRAIN ENHANCEMENT PROBABLE WITH THE
LATTER. STORM MOTION TO THE EAST NORTHEAST AT 10-15 KTS WILL ALLOW
THIS LATTER CONVECTION THAT DEVELOPS TO OUR WEST TO MOVE INTO THE
WESTERN PIEDMONT MID-LATE AFTERNOON...THEN EASTWARD ACROSS THE
REMAINDER OF CENTRAL NC DURING THE LATE AFTERNOON AND EVENING HOURS.
MID LEVEL FLOW ON THE ORDER OF 20-25 KTS SUGGESTS MULTI-CELL STORM
ORGANIZATION WITHIN A WEAKLY TO MODERATELY UNSTABLE ENVIRONMENT OVER
THE CAROLINAS...WITH STRONG WIND GUSTS THE PRIMARY HAZARD. SOME
TRAINING OF CONVECTION AND ASSOCIATED QUICK ONE TO TWO INCHES OF
RAIN WILL ALSO BE POSSIBLE...PARTICULARLY BEFORE EVENING...WHEN
FORECAST CORFIDI VECTORS ARE SMALLEST. PROJECTED LOW LEVEL
THICKNESSES OF 5-10 METERS SHY OF THOSE OBSERVED ON WED SUGGEST
HIGHS WITH PARTIAL AFTERNOON SUNSHINE IN THE LOWER TO MIDDLE 80S.

TONIGHT: A COLD FRONT OVER THE WESTERN TN VALLEY THIS MORNING WILL
CREST THE APPALACHIANS THIS EVENING AND CROSS CENTRAL NC OVERNIGHT -
AROUND MIDNIGHT OR SO OVER THE WESTERN PIEDMONT...TO BETWEEN 4 AND 7
AM IN THE COASTAL PLAIN. THE ARRIVAL OF A DRIER AIR MASS WITH
FRONTAL PASSAGE WILL HERALD THE END OF PRECIPITATION CHANCES...
THOUGH CONVECTIVE COVERAGE SHOULD ALREADY BE UNDERGOING A NOCTURNAL
DIMINISHING TREND WITH COOLING. AREAS OF FOG AND/OR LOW STRATUS ARE
ALSO PROBABLE PRIOR TO FRONTAL PASSAGE...MOST LIKELY AND LONGEST
OVER THE FAR EASTERN PIEDMONT/SANDHILLS AND COASTAL PLAIN. LOWS IN
THE LOWER TO MIDDLE 60S.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 330 AM THURSDAY...

A SHARP...REINFORCING UPPER TROUGH AXIS WILL PIVOT ACROSS THE MIDDLE
ATLANTIC STATES FRI...THEN OFFSHORE FRI NIGHT. STRONG LOW LEVEL CAA
WILL LARGELY OFFSET THE ASSOCIATED FORCING WITH THE UPPER
TROUGH...SO ASIDE FROM A LINGERING CHANCE OF A SHOWER OR STORM IN A
RESIDUALLY MOIST REGIME OVER THE COASTAL PLAIN THROUGH 1-2
PM...STRONG SUBSIDENCE AND ASSOCIATED CLEAR AND STABLE CONDITIONS
WILL PREVAIL. NOT AS WARM...WITH HIGHS IN THE 70S...AND MUCH COOLER
WITH LOWS IN THE 40S OVERNIGHT...AS CANADIAN/CONTINENTAL POLAR HIGH
PRESSURE BUILDS SOUTHEASTWARD.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 255 AM THURSDAY...

SATURDAY AND SUNDAY...

A TERRIFIC WEEKEND IS SHAPING UP AS CANADIAN HIGH PRESSURE WILL
BUILD SOUTH OUT OF THE GREAT LAKES INTO THE EASTERN CONUS. THIS WILL
RESULT IN CLEAR SKIES SATURDAY WITH DRY AND COOLER AIR IN PLACE.
UPPER FLOW WILL BE NORTHWEST AND MODEL CROSS SECTIONS SHOW THAT SOME
HIGH CLOUDINESS COULD MILDLY IMPEDE THE SUNSHINE ON SUNDAY. HIGHS
BOTH DAYS WILL BE MOSTLY IN THE MID 70S. MEANWHILE... SUNDAY
MORNINGS LOW TEMPERATURE WILL BE CONSIDERABLY BELOW NORMAL DUE TO
EXCELLENT RADIATIONAL CONDITIONS...IN THE 45 TO 50 DEGREE RANGE.

MONDAY THROUGH WEDNESDAY....

THE SURFACE HIGH PRESSURE MIGRATES OFFSHORE EARLY NEXT WEEK WHICH
WILL RESULT IN A GRADUAL WARMER AND MOISTER TREND INTO MIDWEEK. WE
WILL BE UNDER A BUILDING LOW AMPLITUDE UPPER RIDGE THROUGH THE
PERIOD WHICH WILL TEND TO SUPPRESS CONVECTION...ESPECIALLY WITH NO
EASILY IDENTIFIABLE FORCING OTHER THAN GENERALLY INCREASING
INSTABILITY WITH LEE TROFFING IN NORTHWEST FLOW AND POTENTIAL FOR
SOME INLAND PENETRATION OF SEA BREEZE CONVECTION IN THE EAST. AS
SUCH...WILL NOT MEDDLE WITH ONGOING SLIGHT CHANCE FOR LATE DAY
CONVECTION MONDAY THROUGH WEDNESDAY. TEMPS WILL BE ON THE UPTICK...
FROM 75 TO 80 ON MONDAY RISING TO 80 TO 85 ON WEDNESDAY...WITH MINS
FOLLOWING A SIMILAR TREND...FROM THE MID 50S MONDAY MORNING TO THE
LOWER 60S WEDNESDAY MORNING.


&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
AS OF 640 AM THURSDAY...

A WEAKENING LINE OF SHOWERS SHOULD CONTINUE TO DISSIPATE DURING THE
NEXT COUPLE OF HOURS...LEAVING GENERALLY DRY CONDITIONS THROUGH
MIDDAY. SUB-VFR CEILINGS AT PRESENT WILL ALSO LIFT AND SCATTER TO
VFR DURING THIS TIME. THEREAFTER...DAYTIME HEATING OF THE MOIST AIR
MASS WILL CAUSE SCATTERED TO NUMEROUS SHOWERS AND STORMS TO DEVELOP
THIS AFTERNOON...AND THESE WILL LIKELY PERSIST IN THE VICINITY OF
CENTRAL NC TERMINALS UNTIL A COLD FRONT SWEEPS ACROSS CENTRAL NC
FROM WEST TO EAST BETWEEN 04-06Z AT TRIAD TERMINALS...TO 09-12Z AT
EASTERN ONES. AREAS OF FOG OR LOW STRATUS IN THE MOIST AIR MASS WILL
ALSO BE POSSIBLE AHEAD OF THE COLD FRONT...MOST LIKELY AT KFAY AND
KRWI BETWEEN 06-12Z.

VFR CONDITIONS WILL OTHERWISE PREVAIL IN CANADIAN HIGH PRESSURE
THROUGH THE HOLIDAY WEEKEND.
-- End Changed Discussion --

&&

.CLIMATE...
-- Changed Discussion --
MORNING LOW TEMPERATURES ON THE 25TH AND 26TH ARE EXPECTED TO BE
NEAR RECORD MIN TEMPS FOR THE DATE.

RECORD MIN TEMP/YEAR SET      MAY 25TH            MAY 26TH

RDU                           43 / 1967           43 / 1979

GSO                           43 / 1956           42 / 1930


.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
-- End Changed Discussion --

&&

$$

SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...MWS
LONG TERM...MLM
AVIATION...MWS
CLIMATE...RAH