-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 200654
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
250 AM EDT MON MAY 20 2013

.SYNOPSIS...
A WEAKENING MID AND UPPER LEVEL TROUGH WILL SETTLE OVER CENTRAL
NORTH CAROLINA TODAY BRINGING MORE UNSETTLED CONDITIONS WITH LOCALLY
HEAVY RAIN. THE TROUGH WILL GRADUALLY MOVE TO NEAR THE COAST ON TUESDAY
REDUCING THE THREAT OF LOCALLY HEAVY RAIN.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 230 AM MONDAY...

...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...

THE SLOW MOVING... ALMOST STUCK MID/UPPER LEVEL TROUGH... LOCATED
OVER WESTERN NC/SC IS EXPECTED TO ONLY SLOWLY BUDGE EASTWARD TODAY
AND TONIGHT. THIS IS A BIT SLOWER THAN HAD BEEN ADVERTISED BY
PREVIOUS MODELS... AND PUTS MUCH OF CENTRAL NORTH CAROLINA IN THE
REGION OF A LOCALLY HEAVY RAIN THREAT TODAY INTO TONIGHT. THE LATEST
MODEL FORECASTS INCLUDING THE HI-RES HRRR GUIDANCE WERE DEPICTING
MUCH OF THE EASTERN PIEDMONT... SANDHILLS AND PORTIONS OF THE
COASTAL PLAIN IN A REGION OF SIGNIFICANT LIFT OUT AHEAD OF THE TROUGH
THROUGH TONIGHT. THE HI-RES HRRR HAD A DECENT HANDLE ON THE CURRENT
AREAS OF SHOWERS. WE WILL GENERALLY FOLLOW THE FORECAST OUTPUT OF
CONVECTION THROUGH THE NEXT 6 HOURS... OR UNTIL SURFACE HEATING
TAKES OVER. THE AREA OF SHOWERS OVER THE SOUTHERN PIEDMONT
AND SANDHILLS SHOULD MOVE SLOWLY NNE INTO THE FAYETTEVILLE AND
RALEIGH AREAS THROUGH DAYBREAK... THEN WEAKEN OUT OVER THE
CENTRAL/NORTHERN COASTAL PLAIN THEREAFTER.

CONVECTION SHOULD AGAIN BLOSSOM THIS AFTERNOON WITH DIFFERENTIAL
HEATING WITH BREAKS IN THE CLOUDS AIDED BY THE SLUG OF COLDER AIR
ALOFT INCREASING LOW LEVEL INSTABILITY. THE INCREASINGLY WEAK
STEERING FLOW SHOULD ALLOW FOR SLOWER MOVING CONVECTION THIS
AFTERNOON AND EVENING... THAN OBSERVED SUNDAY. IN ADDITION... THE
PROLONGED SE FLOW FROM OFF THE GULF STREAM AND WESTERN ATLANTIC WILL
INCREASE DEW POINTS TO NEAR 70 THIS AFTERNOON. THIS POOLING OF DEEP
MOISTURE WITH PRECIPITABLE WATER VALUE FORECASTS ON THE ORDER OF
1.75 INCHES OVER THE EASTERN PIEDMONT AND WESTERN COASTAL PLAIN
SUGGEST A HEAVY RAIN THREAT. THE LACK OF A SIGNIFICANT LOW LEVEL
BOUNDARY AT THE CURRENT TIME SUGGESTS FLOODING WOULD PROBABLY BE
MORE LOCALIZED. THE HAZARDOUS WEATHER OUTLOOK WILL CONTINUE TO
HIGHLIGHT MAINLY URBAN AND SMALL STREAM FLOODING POTENTIAL WITH THE
LOCALLY HEAVY RAIN. HIGHS TODAY SHOULD INCH A BIT HIGHER THAN SUNDAY
WITH A FEW MORE BREAKS IN THE CLOUDS IN THE MORNING. HIGHS GENERALLY
78 TO 83.

SHOWERS AND SCATTERED THUNDERSTORMS SHOULD DIMINISH WITH LOSS OF
HEATING THIS EVENING. WITH THE BASE OF THE TROUGH STILL OVER THE
REGION... WE WILL CONTINUE TO CARRY LOW END POPS AND QPF UNDER 0.25.
LOWS 65-70. STRATUS AND FOG WILL AGAIN BE PROBLEMATIC ESPECIALLY
09Z-13Z/TUE.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
-- Changed Discussion --
AS OF 250 AM MONDAY...

A CONTINUED WEAKENING TREND WITH THE TROUGH AND A GRADUAL SHIFT
EASTWARD WILL MEAN MORE SCATTERED AND LESS CONCENTRATED CONVECTIVE
RAINFALL ON TUESDAY AFTERNOON AND EVENING. SEVERAL MODEL SOLUTIONS
INDICATE THE SUBTROPICAL RIDGE EXTENDING WESTWARD FROM THE WESTERN
ATLANTIC OVER PORTIONS OF NC. AFTER A START TO THE DAY WITH LOW
STRATUS AND AREAS OF FOG... PARTLY SUNNY SKIES ARE EXPECTED. HIGHS
SHOULD REBOUND INTO THE LOWER TO MID 80S. HOWEVER... DEW POINTS WILL
STILL BE IN THE MID TO UPPER 60S. THE COOLER MET/NAM GUIDANCE LOOKS
MORE IN LINE WITH THE CURRENT EXPECTATIONS WITH THE SSW FLOW AND
PLENTY OF LOW LEVEL MOISTURE AND BROKEN AFTERNOON CLOUDINESS. WIDELY
SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED. THIS
ACTIVITY WILL DIMINISH TUESDAY EVENING WITH LOSS OF HEATING. PARTLY
CLOUDY SKIES WITH AREAS OF FOG AGAIN EXPECTED LATE AT NIGHT. LOWS IN
THE MID 60S.
-- End Changed Discussion --

&&


.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 245 PM SUNDAY...

SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WEEK WITH THE APPROACH OF OUR NEXT MID/UPPER LEVEL
TROUGH AND ASSOCIATED COLD FRONT. THERE IS STILL SOME UNCERTAINTY
(MAINLY DUE TO RUN TO RUN INCONSISTENCIES) WITH THE TIMING OF THE
COLD FRONTAL PASSAGE...BUT OVERALL THE TREND HAS BEEN WITH A QUICKER
PASSAGE. IN FACT...THE MODELS ARE IN GENERAL AGREEMENT WITH BRINGING
THE FRONT THROUGH THE FORECAST AREA EARLY FRIDAY...ALMOST 12-18
HOURS EARLIER THAN WHAT MODELS INDICATED 24 HOURS AGO.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. AS OF NOW...IT NOW APPEARS THE WEEKEND
WILL BE DRY AS HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT.
WITH INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND FRIDAY...TEMPS
WILL MOSTLY BE IN THE LOW/MID 80S...WITH SLIGHTLY COOLER TEMPS
EXPECTED FOR THE WEEKEND (GENERALLY IN THE 70S).
-- End Changed Discussion --

&&

.AVIATION /06Z MONDAY THROUGH THURSDAY/...
AS OF 236 AM MONDAY...

LIFR TO IFR CIGS ALONG WITH MVFR VSBYS EXPECTED THROUGH 15Z/MON.
SCATTERED TO NUMEROUS SHOWERS ARE EXPECTED ESPECIALLY FROM KFAY TO
KRDU THROUGH 12Z/MON. IFR TO MVFR CIGS ARE EXPECTED THROUGH THE DAY
WITH NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS... ESPECIALLY EAST
OF KINT/KGSO.... WHERE THE SHOWERS SHOULD BE MORE SCATTERED.

IFR TO LIFR CIGS AND VSBYS SHOULD DEVELOP TONIGHT AND PERSIST INTO
EARLY TUESDAY (13Z-15Z)... THE SCATTERED OUT TO VFR. A FEW SHOWERS
AND THUNDERSTORMS MAY DEVELOP TUESDAY AFTERNOON.

LOW STRATUS AND FOG WILL AGAIN BE PROBLEMATIC TUESDAY NIGHT INTO
EARLY WED... THEN GENERALLY VFR CONDITIONS WED THROUGH THU.
HOWEVER... SCATTERED SHOWER AND THUNDERSTORM CHANCES WILL INCREASE
AGAIN LATE WED AFTERNOON AND ESPECIALLY THURSDAY AS ANOTHER TROUGH
APPROACHES FROM THE WEST.

&&

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

&&

$$

SYNOPSIS...BADGETT
NEAR TERM...BADGETT
SHORT TERM...BADGETT
LONG TERM...KRR
AVIATION...BADGETT