-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 200657
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
257 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/...
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.

&&


.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 255 AM MONDAY...

UPPER LEVEL RIDGE BUILDS BRIEFLY OVER THE AREA ON WEDNESDAY... WHICH
SHOULD DIMINISH THE COVERAGE OF CONVECTION... ALTHOUGH DIURNALLY
DRIVEN THUNDERSTORMS CONTINUE TO BE POSSIBLE WITH THE MOIST AIRMASS
OVER THE AREA. PWATS WILL REMAIN NEAR 1.5... 2 STANDARD DEVIATIONS
ABOVE NORMAL FOR THIS TIME OF YEAR. WITH WEAK SHEAR... EXPECTING
PULSE TYPE STORMS. HIGHS IN THE MID 80S... LOWS MID 60S.

UPPER LEVEL RIDGE SHIFTS OFFSHORE THURSDAY. AFTERNOON THUNDERSTORMS
CONTINUE TO BE POSSIBLE IN THE AFTERNOON THURSDAY AS PWATS REMAIN
ABOVE NORMAL. BULK SHEAR INCREASES TO 25 TO 30 KTS... WHICH MAY
SUPPORT SOME MULTICELL ORGANIZATION. THICKNESSES REMAIN NEAR TO
SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY... FAVORING TEMPERATURES
CONTINUING TO A BE A FEW DEGREES ABOVE NORMAL... WITH HIGHS IN THE
80S AND LOWS IN THE UPPER 60S. THE TROUGH OVER THE MIDWEST MOVES
EASTWARD ON THURSDAY... AND THE ATTENDANT COLD FRONT PUSHES ACROSS
THE REGION FRIDAY. TIMING HAS TRENDED FASTER DURING TODAYS MODEL
RUNS... WITH THE FRONT MAKING IT THROUGH THE AREA EARLY FRIDAY...
AND TO THE CAROLINA COAST FRIDAY MORNING. STRONGEST DYNAMIC FORCING
REMAINS NORTH OVER NEW ENGLAND... AND WITH THE TIMING NOW LOOKING
MORE DIURNALLY UNFAVORABLE... DO NOT EXPECT A THREAT OF SEVERE
WEATHER.
-- 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...SEC
AVIATION...BADGETT