Special Weather Statement, NWS Raleigh, NC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1005 AM EDT FRI JUL 20 2012

.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTH TODAY AS AN UPPER LEVEL
DISTURBANCE PROGRESSES SOUTHEAST FROM THE OHIO VALLEY INTO THE
CAROLINAS. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE
EXPECTED THIS AFTERNOON THROUGH THE WEEKEND AS THE FRONT STALLS OUT
OVER THE REGION.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 1005 AM FRIDAY...

THE LATEST SURFACE ANALYSIS SHOWED A WAVY FRONTAL BOUNDARY...WITH
SURFACE WAVES ALONG THE BOUNDARY...EXTENDING MAINLY ALONG AND NEAR
THE OHIO RIVER...THEN SOUTHEAST FROM SOUTHERN OHIO TOWARD DELMARVA.
A SURFACE TROUGH WAS ALSO LOCATED OVER THE FOOTHILLS AND FAR WESTERN
PIEDMONT. WHILE THE SURFACE GRADIENT WAS SLACK OVER CENTRAL NORTH
CAROLINA...AMDAR SOUNDINGS AS WELL AS THE KGSO 12Z SOUNDING SHOWED
SOME WINDS NEAR THE INVERSION AROUND 20KT. ALREADY...THERE HAVE BEEN
A COUPLE OF GUSTS APPROACHING 20KT ON SURFACE OBSERVATIONS...NOTABLY
AT KFAY.

WHILE DIFFICULT TO RESOLVE ON STANDARD WATER VAPOR IMAGERY...EARLY
MORNING VISIBLE IMAGERY WOULD SUGGEST AN MCV MOVING OVER FAR
NORTHEAST TENNESSEE...WHICH ESSENTIALLY ALL OF THE SHORT-TERM
GUIDANCE FORECASTS MOVING EAST OVER OR VERY NEAR CENTRAL NORTH
CAROLINA DURING THE AFTERNOON. THE RUC IS THE STRONGEST AMONG THE
GFS AND NAM...AND WHILE PRECIPITABLE WATER VALUES ARE CURRENTLY AT A
REGIONAL MINIMUM OVER THE WESTERN THIRD OF THE STATE ON THE LATEST
SPC MESOANALYSIS...WITH THE APPROACH OF THE MCV AND EXPECTED SLOW
EASTWARD PROGRESS OF THE SURFACE TROUGH IN RESPONSE...850MB THETA-E
ADVECTION FROM THE SOUTHWEST SHOULD LIMIT OR NULLIFY ANY
PRECIPITABLE WATER REDUCTION THIS AFTERNOON. 850MB DEW POINTS ARE IN
THE TEENS ON THE LATEST UPPER-AIR ANALYSIS AT THAT LEVEL.

MORNING LOW CLOUDS WERE GRADUALLY DIMINISHING ON THE LATEST VISIBLE
IMAGES...AND WHILE 1000-500MB LAPSE RATES ARE NOT FORECAST
PARTICULARLY HIGH THIS AFTERNOON...TO AROUND 6.5C/KM...AND DCAPE IS
FAIRLY LOW...AROUND 200J/KG...THE COMBINATION OF BETTER SYNOPTIC
FORCING...BETTER AVAILABLE LOW-LEVEL WINDS...AND SOME INCREASING
SHEAR LATE ESPECIALLY NORTHWEST...WHERE 0-6KM SHEAR SHOULD INCREASE
TO AROUND 25KT...SHOULD PROVIDE FOR THE POTENTIAL OF SOME
THUNDERSTORMS ORGANIZING ENOUGH TO HAVE A RISK FOR SEVERE WEATHER
WITH DAMAGING WIND THE PRIMARY SEVERE WEATHER THREAT. SREF
PROBABILISTIC FORECAST FOR GREATER THAN 100 CLOUD-TO-GROUND
LIGHTNING STRIKES SUGGESTS A MAXIMUM OVER THE WESTERN PIEDMONT...AND
THIS SEEMS REASONABLE WHERE THE -10C TO -30C CAPE IS A MAXIMUM...TO
AROUND 600J/KG. THE PREVIOUS FORECAST OF SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS DEVELOPING SEEMS VERY REASONABLE AND
CONTINUED THIS FOR THE AFTERNOON...INCREASING THE RAW NUMBERS ON THE
CHANCES FOR RAIN MAINLY TOWARD THE YADKIN RIVER TO JUST SHY OF
CATEGORICAL BASED ON THE CONSENSUS OF THE ABOVE...PLUS MOS GUIDANCE
AND THE LATEST HRRR WRF OUTPUT. TEMPERATURES IN MOST LOCATIONS...
AFTER A SLOW START IN THEIR RISE DUE TO CLOUDS...SHOULD REACH LOWER
TO MID 90S...POSSIBLY MORE OF A STRUGGLE TO REACH 90 IN THE
IMMEDIATE TRIAD. -DJF

TONIGHT...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL
EVENTUALLY DECREASE FROM W-E OR NW-SE AFTER MIDNIGHT IN ASSOC/W
CONVECTIVE OVERTURNING AND NOCTURNAL STABILIZATION. HOWEVER...WILL
KEEP AT LEAST 20-30% PRECIP CHANCES IN PLACE THE REMAINDER OF THE
NIGHT GIVEN AN APPROACHING UPPER LEVEL TROUGH IN THE PRESENCE OF A
VERY MOIST AND MARGINALLY UNSTABLE AIRMASS. LOW-LEVEL SHEAR BETWEEN
SUNSET AND MIDNIGHT (01-04Z) THIS EVENING (EAST OF HWY 1) IS PROGGED
TO BE SIMILAR TO THAT ANALYZED BY SPC MESOANALYSIS AT 09Z THIS
MORNING (150 M2/S2 OF 0-1 KM HELICITY AND 20-25 KT OF 0-1 KM BULK
SHEAR OVER CENTRAL/EASTERN NC). HOWEVER...DEEP CONVECTION WOULD HAVE
A DIFFICULT TIME REMAINING SFC-BASED BY THE TIME LOW-LEVEL SHEAR
STRENGTHENS IN CENTRAL NC...AND THE PROBABILITY OF A BRIEF/ISOLD TOR
IS TOO LOW TO MENTION. IF THERE WAS A VERY LOW-END POTENTIAL...IT
WOULD LIKELY BE EAST OF I-95 BETWEEN 01-04Z IN AREAS NOT STABILIZED
BY OUTFLOW AND/OR THE SEABREEZE. WITH A VERY MOIST LOW-LEVEL AIRMASS
IN PLACE...EXPECT LOWS TONIGHT IN THE LOWER 70S...OR 71-74F. -VINCENT

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 145 AM FRIDAY...

PULSE THUNDERSTORMS WILL BRING LOCALLY VERY HEAVY RAIN AND GUSTY
WINDS BOTH SATURDAY AND SUNDAY.

A WEAK SURFACE COLD FRONT IS EXPECTED TO DRIFT SOUTHERLY SOUTH
THROUGH TN/WVA/VA SATURDAY... POSSIBLY REACHING NORTHERN NC LATE
SATURDAY AND SATURDAY NIGHT... BEFORE STALLING OVER OUR REGION INTO
SUNDAY. THE STRONG CONFLUENCE ALONG THIS FRONT WILL COMBINE WITH
STRONG SURFACE HEATING TO PROVIDE MORE THAN ADEQUATE LIFT OF VERY
MOIST AIR IN SUPPORT OF THE DEVELOPMENT OF NUMEROUS THUNDERSTORMS
AGAIN SATURDAY AFTERNOON INTO THE EVENING. AREAL AVERAGE QPF SHOULD
BE ON THE ORDER OF 0.50 TO 1 INCH... WITH SOME LOCALLY VERY HEAVY
AMOUNTS IN EXCESS OF 2 INCHES POSSIBLE DUE TO THE MOISTURE POOLING
AND SLOW STORM MOVEMENT. THIS INFORMATION WILL CONTINUE TO BE
MENTIONED IN THE HAZARDOUS WEATHER OUTLOOK (HWO). SUNDAY SHOULD
AGAIN BE JUST AS CONVECTIVELY ACTIVE WITH THE LOW LEVEL CONFLUENCE
ZONE BECOMING NEARLY STATIONARY OVER THE PIEDMONT. QPF SUNDAY WILL
AGAIN INDICATE 0.50 TO 1 INCH AREAL AVERAGES... WITH LOCALLY 2
INCHES AGAIN POSSIBLE. HOPEFULLY... THE HEAVIER AMOUNTS WILL FALL IN
DIFFERENT LOCATIONS THAN THOSE THAT RECEIVE HEAVY AMOUNTS BOTH
FRIDAY AND SATURDAY. THAT IS NOT ALWAYS THE CASE HOWEVER...
THEREFORE SOME LOCAL AREAS MAY RECEIVE OVER 4 INCHES OF RAIN TOTAL
TODAY THROUGH SUNDAY.

SHEAR IS FORECAST TO CONTINUE TO BE LACKING WHICH OFTEN WILL LEAD TO
THE CONVECTIVE MODE BEING "PULSE"... OR TYPICAL SUMMERTIME STRONG
THUNDERSTORMS. THIS MEANS LESS IN THE WAY OF ORGANIZED SEVERE
STORMS. HOWEVER... EVEN THOUGH "ORGANIZED AND WIDESPREAD" SEVERE
THUNDERSTORMS ARE NOT FORECAST... THERE WILL LIKELY BE BE A RAPID
DEVELOPMENT OF "PULSE" THUNDERSTORMS BOTH SATURDAY AND SUNDAY.  SOME
OF THESE MAY BECOME LOCALLY SEVERE WITH DAMAGING WIND GUSTS TO 60
MPH POSSIBLE. WE WILL HIGHLIGHT THIS LOCAL PULSE SEVERE CHANCE AS
WELL IN THE HWO FOR BOTH DAYS. HIGHS SATURDAY ARE FAVORED TO BE IN
THE 86-92 RANGE... N TO S. LOWS SATURDAY NIGHT... 69-73. HIGHS
SUNDAY MAY BE A BIT COOLER (ONLY DUE TO THE FORECAST HIGH DEW POINTS
AND WETTER GROUND BY THEN) 85-90.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 145 AM FRIDAY...

ANOTHER HOT AND HUMID WEEK...WITH A CHANCE OF MAINLY AFTERNOON AND
EVENING THUNDERSTORMS.

STRONG UPPER RIDGING IS FORECAST TO BEGIN TO EXTEND EASTWARD FROM
THE CENTRAL UNITED STATES TO NEAR THE APPALACHIANS BY MID WEEK. THE
BOUNDARY THAT IS FORECAST TO BRING THE THUNDERSTORMS TO OUR REGION
THIS WEEKEND IS FORECAST TO DISSIPATE OVER OUR AREA MONDAY THROUGH
TUESDAY. AS WE LOSE THE INFLUENCE OF THE BOUNDARY (LIFT/MOISTURE
POOLING/CONVERGENCE) WE WILL SEE THE WIDESPREAD STORMS OF THE
WEEKEND BECOME SCATTERED DURING MONDAY AND TUESDAY. A NW FLOW ALOFT
MAY NOT TURN OUT TO BE THAT MUCH DRIER MID TO LATE WEEK AS
DISTURBANCES ALOFT MAY TRIGGER AT LEAST SCATTERED DIURNAL STORMS ALL
WEEK. WE WILL MAINTAIN POPS OF AT LEAST CLIMATOLOGY FOR LATE JULY
(35 PERCENT OR SO) MOST OF THE WEEK.

THE HEAT WILL ALSO BEGIN TO RETURN WITH LESS IN THE WAY OF CLOUDS/
STORMS DURING THE PM HOURS. THEREFORE...HIGHS ARE EXPECTED TO BE IN
THE UPPER 80S TO LOWER 90S MONDAY...90-95 TUESDAY... THEN MOSTLY MID
90S BY THURSDAY. IT WILL CONTINUE VERY MUGGY WITH DEW POINTS IN THE
70S. LOWS WILL ALSO BE IN THE 70S.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AS OF 1005 AM FRIDAY...

MVFR CEILINGS WILL LIFT AND BECOME VFR DURING THE MORNING...WITH
MOSTLY VFR CONDITIONS EXPECTED THEREAFTER THROUGH 12Z. SURFACE WINDS
WILL SHOW SOME GUSTINESS...POSSIBLY TO NEAR 20KT PARTICULARLY TOWARD
KFAY AND KRWI THIS AFTERNOON. NUMEROUS SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP OVER CENTRAL NC THIS AFTERNOON AND LINGER INTO
THIS EVENING AS A COLD FRONT APPROACHES THE AREA FROM THE NORTH.
WILL MENTION VCSH AT ALL TAF SITES BY 17-18Z...WITH A TEMPO GROUP
FOR IFR CONDITIONS AND GUSTY WINDS BETWEEN 18-22Z AT INT/GSO AND
19-23Z AT RDU/RWI/FAY...WHEN DEEP CONVECTION WILL BE MOST LIKELY.
ISOLD TO SCATTERED SHOWERS AND STORMS WILL REMAIN POSSIBLE THROUGH
THE END OF THE TAF PERIOD...THOUGH CONVECTION SHOULD WEAKEN AND
DECREASE IN COVERAGE AFTER 03Z THIS EVENING.

LOOKING AHEAD:
EXPECT SCATTERED TO NUMEROUS SHOWERS AND STORMS DURING THE AFTERNOON
AND EVENING HOURS SATURDAY AND SUNDAY AS THE FRONT STALLS OUT OVER
VA/NC. SUB-VFR FOG AND/OR CEILINGS WILL BE POSSIBLE DURING THE
PRE-DAWN HOURS EACH MORNING IN ASSOCIATION WITH A MOIST AIRMASS IN
PLACE. AFTERNOON AND EVENING SHOWERS/STORMS AND PRE-DAWN FOG/STRATUS
WILL REMAIN POSSIBLE THROUGH EARLY/MID NEXT WEEK IN ASSOCIATION WITH
A SEASONABLY MOIST AIRMASS IN THE PRESENCE OF NW FLOW ALOFT. -VINCENT

&&

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

&&

SYNOPSIS...VINCENT
NEAR TERM...DJF/VINCENT
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...DJF/VINCENT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RALEIGH NC
428 AM EDT FRI JUL 20 2012

NCZ007>011-021>028-038>043-073>078-083>086-088-089-210830-
PERSON-GRANVILLE-VANCE-WARREN-HALIFAX-FORSYTH-GUILFORD-ALAMANCE-
ORANGE-DURHAM-FRANKLIN-NASH-EDGECOMBE-DAVIDSON-RANDOLPH-CHATHAM-WAKE-
JOHNSTON-WILSON-STANLY-MONTGOMERY-MOORE-LEE-HARNETT-WAYNE-ANSON-
RICHMOND-SCOTLAND-HOKE-CUMBERLAND-SAMPSON-
428 AM EDT FRI JUL 20 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

A COLD FRONT WILL MOVE SLOWLY SOUTH THROUGH VIRGINIA TODAY AND
TONIGHT AS AN UPPER LEVEL DISTURBANCE TRACKS SOUTHEAST TOWARD THE
CAROLINAS. IN ADVANCE OF THE FRONT...NUMEROUS SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER CENTRAL NORTH CAROLINA
THIS AFTERNOON. ANY STORMS THAT DEVELOP WILL HAVE THE POTENTIAL TO
BECOME SEVERE...WITH A PRIMARY THREAT OF DAMAGING WINDS AND HAIL
UP TO THE SIZE OF QUARTERS. LOCALLY HEAVY RAINFALL AND ISOLATED
FLOODING WILL ALSO BE POSSIBLE...THOUGH PRIMARILY IN URBAN AREAS.
THE THREAT FOR SEVERE WEATHER WILL BE GREATEST BETWEEN 2 PM THIS
AFTERNOON AND 11 PM THIS EVENING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING
THE AFTERNOON AND EVENING HOURS ON SATURDAY AND SUNDAY AS THE
FRONT STALLS OUT OVER THE REGION. ISOLATED SEVERE THUNDERSTORMS
WILL BE POSSIBLE...IN ADDITION TO LOCALLY HEAVY RAINFALL AND
ISOLATED FLOODING.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS SHOULD MONITOR THE LATEST DAY 1 CONVECTIVE
OUTLOOK FROM THE STORM PREDICTION CENTER...AND BE PREPARED FOR
THE POSSIBILITY OF SEVERE THUNDERSTORM WATCHES AND WARNINGS LATER
THIS AFTERNOON AND EVENING.

VINCENT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
129 PM EDT FRI JUL 20 2012

NCZ042-043-075>078-083>086-088-089-201830-
ANSON-CUMBERLAND-HARNETT-HOKE-JOHNSTON-LEE-MOORE-RICHMOND-SAMPSON-
SCOTLAND-WAYNE-WILSON-
129 PM EDT FRI JUL 20 2012

...SHOWERS AND STRONG THUNDERSTORMS WILL BECOME MORE NUMEROUS ACROSS
THE SOUTHERN TIER OF CENTRAL NORTH CAROLINA THIS AFTERNOON. STORMS
WILL MOVE ACROSS SAMPSON...HARNETT...WAYNE...JOHNSTON...WILSON...
SCOTLAND...RICHMOND.. .MOORE...LEE...CUMBERLAND...ANSON AND HOKE
COUNTIES THROUGH 230 PM EDT...

AT 123 PM EDT...DOPPLER RADAR INDICATED THUNDERSTORMS STRETCHING
WILSON AND GOLDSBORO WEST ACROSS THE SOUTHERN COASTAL PLAIN THROUGH
FAYETTEVILLE...RAEFORD...AND ROCKINGHAM TO WADESBORO. THE STORMS
WERE MOVING MOVING EAST AT 20 MPH.

SOME LOCATIONS IN THE PATH OF THESE STORMS INCLUDE WILSON...
GOLDSBORO...FAYETTEVILLE...FORT BRAGG...RAEFORD...LAURINBURG...
ROCKINGHAM AND WADESBORO.

HAZARDS INCLUDE...
HEAVY DOWNPOURS.
GUSTY WINDS OF 30 TO 40 MPH.

THESE STORMS WILL PRODUCE HEAVY RAINFALL...WHICH MAY CAUSE MINOR
FLOODING IN LOW LYING AREAS INCLUDING DITCHES...CREEKS...ROADWAYS AND
AREAS OF POOR DRAINAGE. MOTORISTS SHOULD REDUCE DRIVING SPEEDS TO
AVOID HYDROPLANING.

&&

LAT...LON 3480 7968 3481 8029 3498 8031 3517 7976
      3516 7962 3520 7966 3581 7788 3560 7778
      3518 7783 3515 7790 3518 7816 3493 7815
      3483 7847 3483 7890 3495 7904 3483 7919
      3483 7934 3477 7933 3463 7946
TIME...MOT...LOC 1723Z 251DEG 18KT 3507 7890

13