Special Weather Statement, NWS Raleigh, NC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
950 PM EDT THU MAY 26 2011

.SYNOPSIS...
HIGH PRESSURE CENTERED WELL OFF THE SOUTHEAST COAST WILL CONTINUE TO
EXTEND WESTWARD INTO THE SOUTHEAST THROUGH FRIDAY... RESULTING IN
UNSEASONABLY WARM TEMPERATURES. A COLD FRONT WILL APPROACH FROM THE
WEST LATE FRIDAY BEFORE WEAKENING... AND THE CHANGE IN AIR MASS WILL
BRING TEMPERATURES BACK DOWN TO MORE SEASONABLE READINGS FOR THE
HOLIDAY WEEKEND.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 945 PM THURSDAY...

A LINE OF SHOWERS AND THUNDERSTORMS TO THE WEST OF CENTRAL NC ACROSS
THE NC MOUNTAINS AND FOOTHILLS CONTINUES TO MOVE SLOWLY EASTWARD AS
THE INDIVIDUAL CELLS WITHIN THE LINE ARE MOVING TO THE
NORTH-NORTHEAST AS THE 850-300 MB MEAN WIND IS OUT OF THE
SOUTH-SOUTHWEST (WHILE THE MID/UPPER LEVEL TROUGH SLOWLY SHIFT
EASTWARD). EXPECT THIS EASTWARD PROGRESSION TO CONTINUE AND
POTENTIALLY GAINING EASTWARD SPEED AS THE ACTIVITY APPEARS TO
BECOMING MORE OUTFLOW DRIVEN. HOWEVER... THE QUESTION REMAINS HOW
QUICKLY WILL WE STABILIZE BEFORE ANY ACTIVITY CAN MAKE IT INTO OUR
NORTHWEST OR WESTERN PIEDMONT COUNTIES. HIGH RESOLUTION NEAR TERM
MODELS SHOW A WEAKENING LINE MAKING IT INTO OUR WESTERN COUNTIES
LATE THIS EVENING INTO THE EARLY MORNING HOURS OF FRIDAY... BEFORE
DECREASING IN COVERAGE OR DISSIPATING. THUS... WILL UP POPS ACROSS
THE WESTERN PIEDMONT INTO THE SOLID CHANCE AND/OR LOW END LIKELY
CATEGORY LATE THIS EVENING INTO THE EARLY MORNING HOURS...
DECREASING TO SLIGHT CHANCES POPS AFTER 08Z AND GENERALLY WEST OF
RALEIGH. GIVEN MID LEVEL LAPSE RATES OF 7 DEGREE C/KM REMAIN ACROSS
WESTERN PORTIONS OF OUR AREA ALONG WITH SURFACE BASED CAPE OF 1500
TO 2000 J/KG WE COULD SEE SOME STORMS PRODUCE DAMAGING WINDS AND
LARGE HAIL. THUS... WILL CONTINUE MENTION OF SVR WX IN THE HWO...
AND CONTINUE TO MONITOR RADAR TRENDS. EXPECT OVERNIGHT LOWS TO BE IN
THE UPPER 60S TO LOW 70S... WITH PERHAPS LOW STRATUS DEVELOPING
PRIOR TO SUNRISE. -BSD

THE MAIN DPVA ASSOCIATED WITH THE INCREASINGLY NEGATIVELY TILED
TROUGH AXIS IS POISED TO LIFT ACROSS THE CWA DURING THE DAY FRIDAY.
LOW LEVEL CONVERGENCE IS FORECAST TO WEAKEN TREMENDOUSLY AS THE COLD
FRONT RUNS INTO THE DOMINANT LOW TO MID LEVEL RIDGE OVER THE
ATLANTIC AND WASHES OUT.  HOWEVER...CONSIDERING THE TILT OF THE
UPPER TROUGH AND PRECIPITABLE WATER VALUES INCREASING TO NEAR 1.5
INCHES... FEEL LIKELY SHOWERS WITH ISOLATED STORMS IS WARRANTED
ACROSS THE WEST. STRATUS IS LIKELY TO STIFLE DESTABILIZATION IN
THE WEST...BUT MODELS SHOW 1000 TO 2000 J/KG OF CAPE DEVELOPING IN
THE EAST WHERE BREAKS IN CLOUD COVER DEVELOP. DESPITE WEAK LOW
LEVEL FORCING...WITH 30 TO 40 KNOT OF ZERO TO SIX KILOMETER BULK
SHEAR...STORMS MAY INTENSIFY AS THEY REACH AN INSTABILITY GRADIENT
AND 12Z HI-RES WRF SOLUTIONS MAY BE UNDERDONE. HIGHS ARE TRICKY
TOMORROW AND THERE IS BUST POTENTIAL BASED ON POSSIBLE STRATUS
PRECIPITATION IN THE WEST. HAVE HIGHS 82 TO 86 WEST TO EAST. -SMITH

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 255 PM THURSDAY...

MODEL GUIDANCE CONTINUES TO DRIFT MID/UPPER TROUGH ACROSS CENTRAL
NORTH CAROLINA FRIDAY NIGHT INTO SATURDAY. AIR MASS PROJECTED TO
BE QUITE MOIST FRIDAY NIGHT WITH PRECIPITABLE WATER VALUES 1.5
TO 1.6 INCHES. RH CROSS SECTIONS DEPICT SOME DRYING BETWEEN 850
AND 500 MILLIBARS BY SATURDAY AFTERNOON...EVIDENT OF SOME
SUBSIDENCE ASSOCIATED WITH UPPER RIDGE BEGINNING TO BUILD FROM THE
SOUTHWEST. MODELS DEPICTING VARYING DEGREES OF CONFLUENCE FRIDAY
NIGHT THOUGH ALL-IN-ALL NOT OVERLY IMPRESSIVE. HOWEVER TROUGH WILL
INITIALLY INTERACT WITH A SLIGHTLY UNSTABLE AIR MASS AS SURFACE
BASED CAPE VALUES 1200-1800 J/KG AND MIXED LAYER CAPE VALUES 1000
TO 1200 J/JG...MAINLY EAST OF HIGHWAY ONE WHERE PARTIAL SUN
PROBABLE. BULK SHEAR ALSO EXPECTED TO WEAKEN WITH TIME BUT STILL
SUPPORT OF ORGANIZED CONVECTION IN THE WEST EARLY FRIDAY EVENING.
FOR NOW WILL MAINTAIN LIKELY POPS FRIDAY EVENING IN THE WEST WITH
POPS DECREASING FARTHER EAST (SLIGHT-SMALL CHANCE COASTAL PLAIN).
EXPECT SCATTERED CONVECTION TO ADVANCE TO THE HIGHWAY ONE CORRIDOR.
AFTERWHICH...DYNAMICS WANE SIGNIFICANTLY TO SUGGEST CHANCE POPS
FOR LATE NIGHT INTO EARLY SATURDAY.

SATURDAY...MID LEVEL SHEAR AXIS LIES ACROSS THE COASTAL PLAIN.
INSTABILITY BY AFTERNOON UP TO 2000 J/KG (SURFACE BASED). HOWEVER
MID LAYERS DRY OUT APPRECIABLY WHICH MAY LIMIT CONVECTIVE COVERAGE.
WILL GO WITH A 30 TO 40 PERCENT CHANCE SATURDAY IN THE COASTAL
PLAIN WITH LESSER AMOUNTS (SLIGHT) IN THE WEST.

MORNING STRATUS SATURDAY MORNING WILL EVENTUALLY GIVE WAY TO PARTIAL
SUN BY EARLY AFTERNOON. MAXIMUM TEMPERATURES MID 80S LOOK
REASONABLE THOUGH IF CLOUDS LINGER THROUGH 2 PM...MAXIMUM
TEMPERATURES MAY BE TOO WARM BY 4 TO 5 DEGREES.

CLEARING SKIES SATURDAY NIGHT MAY ALLOW AREAS OF FOG TO DEVELOP BY
DAYBREAK SUNDAY. MINIMUM TEMPERATURES MAINLY IN THE MID 60S.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 225 PM THURSDAY...

TREND OF THE GFS MODEL THE PAST FOUR RUNS SUGGEST THAT THE
ECMWF/CANADIAN MAY BE MORE CORRECT WITH THE FARTHER NORTH-
NORTHWEST POSITION OF THE MID AND UPPER LEVEL ANTICYCLONES EARLY
NEXT WEEK. IN FACT THE LATEST GFS LOW LEVEL THICKNESSES FOR MONDAY
THROUGH WEDNESDAY LOWERED 10-12M FROM ITS EARLIER VERSIONS. THUS
ADJUSTMENTS MADE EARLY THIS MORNING ON THE MAXIMUM TEMPERATURES
APPEAR ON TARGET WITH HIGHS MONDAY THROUGH WEDNESDAY 90 TO 95
DEGREES.

AS CENTER OF ANTICYCLONE RETROGRADES TOWARD THE MID MISSISSIPPI
VALLEY WEDNESDAY THROUGH THURSDAY.... MEDIUM RANGE MODELS SUGGEST
A SHORT WAVE IN THE WESTERLIES TRACKING ACROSS SOUTHERN NEW
ENGLAND THEN OFFSHORE...DRAGGING A COLD FRONT BACK DOOR STYLE
ACROSS CENTRAL NORTH CAROLINA WEDNESDAY NIGHT THROUGH THURSDAY
MORNING. STILL HIGHLY UNCERTAIN ON TIMING AND WHETHER THERE WILL
BE ENOUGH MOISTURE AND LIFT TO GENERATE SCATTERED SHOWERS AND
THUNDERSTORMS THIS FAR OUT. FOR NOW WILL REFRAIN FROM INTRODUCING
A POP BUT DID LOWER MAXIMUM TEMPERATURES THURSDAY 3 TO 5 DEGREES
FROM WEDNESDAY'S MAXIMUM TEMPERATURES.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 810 PM...

A SOUTH WIND COMPONENT KEEPING SHOWERS AND THUNDERSTORMS PINNED TO
THE EASTERN SLOPES OF THE NORTH CAROLINA MOUNTAINS AT THIS TIME.
AN UPPER TROUGH OVER TENNESSEE WILL REACH THE NORTH CAROLINA
FOOTHILLS BY SUNSET FRIDAY... RESULTING IN INCREASING CHANCES FOR
SHOWERS OR THUNDERSTORMS SPREADING ACROSS CENTRAL NORTH CAROLINA
LATE TONIGHT INTO SATURDAY... WITH BEST CHANCES NOT UNTIL LATE IN
THE TAF PERIOD.

SUSTAINED WINDS TONIGHT SUGGEST MINIMAL FOG THREAT... WHILE
HIGHER MOISTURE IN THE WESTERN PIEDMONT SUGGESTS A HIGHER THREAT
FOR IFR STRATUS THAN EAST... BUT LIKELY NOT UNTIL BEFORE SUNRISE.

SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE SATURDAY... THEN NO
MORE THAN ISOLATED AFTERNOON THUNDERSTORMS INTO TUESDAY. SOME FOG OR
STRATUS POSSIBLE EACH NIGHT TOWARD SUNRISE.

&&

.CLIMATE...
DAILY RECORD TEMPERATURES FOR MAY 26-27.

RALEIGH-DURHAM AIRPORT (RDU)

DATE    MAX     YEAR    HI MIN  YEAR

26      94      1953    70      2004
27      92      1944    72      1991

PIEDMONT TRIAD AIRPORT (GSO)

DATE    MAX     YEAR    HI MIN  YEAR

26      93      1953    69      1965
27      95      1941    72      1991

&&

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

&&

SYNOPSIS...
NEAR TERM...BSD/SMITH
SHORT TERM...WSS
LONG TERM...WSS
AVIATION...
CLIMATE...WFO RAH

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE RALEIGH NC
1042 PM EDT THU MAY 26 2011

NCZ021-022-038-039-073-074-083-280245-
FORSYTH-GUILFORD-DAVIDSON-RANDOLPH-STANLY-MONTGOMERY-ANSON-
1042 PM EDT THU MAY 26 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA.

.DAY ONE...THROUGH TONIGHT.

A LINE OF SHOWERS AND THUNDERSTORMS WILL MOVE INTO THE WESTERN
PIEDMONT LATE THIS EVENING INTO EARLY FRIDAY MORNING. A FEW OF THESE
STORMS MAY PRODUCE DAMAGING WIND GUSTS OVER 60 MPH AND QUARTER
SIZE HAIL.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

SCATTERED STORMS FRIDAY AFTERNOON MAY PRODUCE ISOLATED WIND GUSTS
OVER 40 MPH... BRIEF HEAVY RAIN... AND SMALL HAIL. HOWEVER...
HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE ENCOURAGED TO REPORT ANY SEVERE OR
SIGNIFICANT WEATHER IMMEDIATELY TO THE NATIONAL
WEATHER SERVICE.

NCZ007>011-023>028-040>043-075>078-084>086-088-089-280245-
PERSON-GRANVILLE-VANCE-WARREN-HALIFAX-ALAMANCE-ORANGE-DURHAM-
FRANKLIN-NASH-EDGECOMBE-CHATHAM-WAKE-JOHNSTON-WILSON-MOORE-LEE-
HARNETT-WAYNE-RICHMOND-SCOTLAND-HOKE-CUMBERLAND-SAMPSON-
1042 PM EDT THU MAY 26 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA.

.DAY ONE...THROUGH TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

SCATTERED STORMS FRIDAY AFTERNOON MAY PRODUCE ISOLATED WIND GUSTS
OVER 40 MPH... BRIEF HEAVY RAIN... AND SMALL HAIL. HOWEVER...
HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE ENCOURAGED TO REPORT ANY SEVERE OR
SIGNIFICANT WEATHER IMMEDIATELY TO THE NATIONAL
WEATHER SERVICE.

77

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
1118 PM EDT THU MAY 26 2011

NCZ022-039-073-074-270400-
GUILFORD-MONTGOMERY-RANDOLPH-STANLY-
1118 PM EDT THU MAY 26 2011

...STRONG THUNDERSTORMS WILL MOVE ACROSS STANLY...RANDOLPH...
MONTGOMERY AND GUILFORD COUNTIES THROUGH MIDNIGHT EDT...

AT 1117 PM EDT...DOPPLER RADAR INDICATED A LINE OF STRONG
THUNDERSTORMS ALONG A LINE EXTENDING FROM HIGH POINT TO 11 MILES
SOUTHWEST OF ASHEBORO TO 12 MILES NORTH OF WADESBORO...MOVING EAST
AT 60 MPH. STRONG WINDS OF UP TO 50 MPH ARE OCCURRING WELL AHEAD OF
ANY RAINFALL.

LOCATIONS IN THE PATH OF THESE STORMS INCLUDE...JAMESTOWN...AND...
ULAH...PLEASANT GARDEN...AND...STAR...FOREST OAKS...AND...RAMSEUR...
STALEY...AND...LIBERTY.

HAZARDS INCLUDE...
GUSTY WINDS OF 40 TO 50 MPH.

SEEK SHELTER IN A NEARBY BUILDING OR VEHICLE. STRONG WINDS ARE
CAPABLE OF KNOCKING DOWN SMALL TREES AND BLOWING AROUND TRASH CANS...
POTTED PLANTS...LAWN FURNITURE AND OTHER LIGHT OUTDOOR OBJECTS.

&&

LAT...LON 3546 8030 3551 8016 3551 8007 3555 8004
      3623 8002 3622 7954 3554 7955 3551 7977
      3520 7968 3523 8038
TIME...MOT...LOC 0317Z 269DEG 50KT 3594 8003 3561 7993
          3514 8004

KRR