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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 210541
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
140 AM EDT TUE MAY 21 2013

.SYNOPSIS...
-- Changed Discussion --
A TROUGH OVER THE REGION WILL GRADUALLY WEAKEN THROUGH WEDNESDAY.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 PM MONDAY...

THROUGH TONIGHT: THE MAJORITY OF THE SHOWERS HAVE DISSIPATED OR
MOVED OUT OF THE AREA THIS EVENING. A FEW ISOLATED SHOWERS HAVE
DEVELOPED DURING THE PAST COUPLE HOURS...BUT HAVE NOT BEEN HEAVY OR
LONG LASTING. THE 00Z UPPER AIR ANALYSES SHOW THE WAVE OVER CENTRAL
NC FROM 850-500 MB...WITH A SHORTWAVE TROUGH TO THE SOUTHWEST AT 250
MB. AS A PAIR OF VORTICITY MAXIMA EMBEDDED IN THE MID LEVEL TROUGH
PIVOTS OVER EASTERN NC OVERNIGHT...ADDITIONAL SHOWERS COULD DEVELOP
ACROSS THE SOUTHEAST. THE 00Z SOUNDING AT KGSO STILL YIELDS MLCAPE
AROUND 1000-1500 J/KG WITH A MOIST BOUNDARY LAYER AND RELATIVELY
DRIER AIR IN THE MID LEVELS. THE LATEST HRRR SHOWS ADDITIONAL SHOWER
ACTIVITY DEVELOPING ACROSS THE SOUTHEAST AROUND MIDNIGHT AS A MID
LEVEL DISTURBANCE MOVES OVER THE AREA. HAVE INCREASED RAIN CHANCES
IN THE EAST OVERNIGHT TO REFLECT THE POTENTIAL DEVELOPMENT.
TEMPERATURES ACROSS THE AREA ARE IN THE UPPER 60S TO LOW 70S...WITH
OVERNIGHT LOWS IN THE MID 60S EXPECTED.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...

TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.

MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.

TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 240 PM MONDAY...

FOR WEDNESDAY...WEAK SHORTWAVE RIDGING WILL BUILD OVER THE AREA...
WHILE AT THE SURFACE...THE BERMUDA HIGH WILL RIDGE WESTWARD INTO THE
CAROLINAS. ALL OF THIS WILL TRANSLATE TO AN EVEN FURTHER DECREASE IN
PRECIP COVERAGE. HOWEVER...SUFFICIENT MOISTURE WILL STILL BE IN
PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR 1.5 INCHES OR
SO. THEREFORE...AM STILL EXPECTING TO SEE WIDELY SCATTERED TO
SCATTERED DIURNALLY DRIVEN CONVECTION...WITH THE HIGHEST CHANCES
BEING ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. HIGHS ONCE
AGAIN SHOULD BE IN THE MID/UPPER 80S...WITH OVERNIGHT LOWS IN THE
MID/UPPER 60S.

SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WORK WEEK AS THE MID/UPPER LEVEL RIDGE SHIFTS
OFFSHORE AHEAD OF OUR NEXT MID/UPPER LEVEL TROUGH AND ASSOCIATED
COLD FRONT. MODELS REMAIN IN GENERAL AGREEMENT WITH BRINGING THE
FRONT THROUGH THE FORECAST AREA LATE THURSDAY NIGHT/EARLY FRIDAY.
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. BULK SHEAR VALUES WILL INCREASE TO
AROUND 25 KNOTS OR SO...THEREFORE BETTER STORM ORGANIZATION IS
EXPECTED...HOWEVER THE BEST UPPER LEVEL FORCING WILL PASS WELL TO
OUR NORTH. THEREFORE...EVEN THOUGH AN ISOLATED SEVERE STORM CANNOT
BE COMPLETELY RULED OUT...THE OVERALL THREAT REMAINS LOW AT THIS
TIME. WITH THE INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND
FRIDAY...TEMPS WILL MOSTLY BE IN THE LOW/MID 80S.

IT STILL APPEARS THE WEEKEND AND INTO EARLY NEXT WEEK WILL BE DRY AS
HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT. SLIGHTLY COOLER
TEMPS ARE EXPECTED DURING THIS TIME FRAME...GENERALLY THE UPPER 70S
TO LOWER 80S...WITH OVERNIGHT LOWS IN THE 50S.

&&

.AVIATION /00Z TUESDAY THROUGH FRIDAY/...
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AS OF 140 AM TUESDAY...

24 HOUR TAF PERIOD:

LIFR TO IFR CIGS AND MVFR VSBYS EXPECTED THROUGH 13Z-15Z TODAY...
THEN VFR CONDITIONS THIS AFTERNOON. ISOLATED TO SCATTERED
THUNDERSTORMS POSSIBLE THIS AFTERNOON. MVFR TO IFR CIGS AND VSBYS
MAY REDEVELOP LATER TONIGHT 09Z-12Z... FOLLOWED BY VFR CONDITIONS
WEDNESDAY.

LONG TERM:
AREAS OF STRATUS (LIFR TO IFR CIGS) AND VSBYS ARE EXPECTED AGAIN
THURSDAY MORNING. OTHERWISE... MOSTLY VFR CONDITIONS THU-FRI WITH A
CHANCE OF SHOWERS AND THUNDERSTORMS WITH MVFR CIGS/VSBYS BOTH DAYS.
-- End Changed Discussion --
&&

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

&&

$$

SYNOPSIS...PWB
NEAR TERM...KC
SHORT TERM...ELLIS
LONG TERM...KRR
AVIATION...PWB