Special Weather Statement, NWS Raleigh, NC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
340 PM EDT MON JUL 30 2012

.SYNOPSIS...
A STATIONARY FRONT OVER EASTERN NORTH CAROLINA WILL SLOWLY WEAKEN
LATE TODAY THROUGH TONIGHT. A SERIES OF UPPER LEVEL DISTURBANCES
WILL MOVE SOUTHEAST THROUGH THE REGION THROUGH WEDNESDAY... THEN
UPPER LEVEL HIGH PRESSURE WILL BUILD IN FROM THE WEST LATE IN THE
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 320 PM MONDAY...

REST OF THE AFTERNOON THROUGH TONIGHT... THE DIFFUSE LOW-LEVEL
FRONTAL ZONE PERSISTS OVER CENTRAL NC THIS AFTERNOON WITH A BROAD
CORRIDOR OF LOW LEVEL MASS CONVERGENCE AND 70+ SURFACE DEW POINTS
FROM THE TRIANGLE SOUTH AND EAST. STORM COVERAGE HAS BEEN GREATEST
FROM RALEIGH SOUTH AND EAST WITHIN THE AREA OF BEST MOISTURE AND
INSTABILITY... AND ADDITIONAL SCATTERED CONVECTION OVER THE HIGHER
TERRAIN HAS LARGELY HELD TO OUR NW. STORMS HAVE BEEN PROPAGATING
TOWARD THE WEST... DRIVEN LARGELY BY THE LOW LEVEL WIND FIELD AND
OUTFLOW MOVEMENT. WILL PLACE THE HIGHEST CHANCES OF SHOWERS/STORMS
INITIALLY OVER THE SOUTH AND EAST... TRANSLATING INTO THE WESTERN
PIEDMONT OVER THE NEXT SEVERAL HOURS AS THE OUTFLOWS SPREAD WESTWARD
AND WITH PARTIAL CONTRIBUTION TO LIFT FROM WANING DPVA WITH THE WEAK
WAVE NOW APPROACHING THE SRN APPALACHIANS. THIS FOLLOWS THE
SIMULATED REFLECTIVITY PATTERN OF THE LATEST 4 KM WRF-NMM AND
WRF-ARW. DEEP LAYER SHEAR OVER CENTRAL NC REMAINS SMALL AND
INSTABILITY MARGINAL WITH UNIMPRESSIVE MID LEVEL LAPSE RATES... THUS
ANY VIGOROUS UPDRAFTS SHOULD BE SHORT-LIVED AND ISOLATED WITH ONLY A
MINOR THREAT OF STRONG-WIND-GENERATING STORMS. EXPECT ACTIVITY TO
WIND DOWN WITHIN A FEW HOURS AFTER NIGHTFALL WITH LOSS OF HEATING
AND THE ABSENCE OF ANY LARGE SCALE FORCING FEATURES... AS WELL AS
WITH THE DEPARTURE OF A WEAK SURFACE LOW ALONG THE FRONT WHICH
TRACKS NORTHEASTWARD AND OFF THE NE NC COAST LATE TONIGHT. MODELS
DEPICT THE VORTICITY MAXIMUM NOW OVER THE MIDWEST DROPPING SOUTHEAST
AROUND THE PERIPHERY OF THE TX PANHANDLE ANTICYCLONE INTO AL/GA LATE
TONIGHT... BUT MUCH OF THIS ASSOCIATED CONVECTION SHOULD HOLD WEST
AND SOUTH OF THE CWA. THE LIGHT/VARIABLE WINDS AND HIGH SURFACE RH
TONIGHT ALONG WITH LIMITED MID-HIGH CLOUDS WILL FACILITATE FOG
DEVELOPMENT LATE TONIGHT. LOWS 68-72. -GIH

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
AS OF 340 PM MONDAY...

THE MEAN MID LEVEL TROUGH OVER ERN NOAM STEADILY SHARPENS OVER AND
JUST EAST OF THE APPALACHIANS THROUGH TUESDAY NIGHT. THE NAM AND GFS
AGREE ON A CONVECTIVE COMPLEX TRACKING SOUTHEASTWARD TO THE
SOUTHWEST OF NC EARLY TUESDAY MORNING... WHILE TO OUR EAST... THE
LOW LEVEL FRONTAL ZONE IS EXPECTED TO PERSIST WHILE CONTINUING TO
SLOWLY WEAKEN... AS A MID LEVEL VORTICITY MAXIMUM SHEARS OFF TO THE
NORTHEAST AWAY FROM THE FORECAST AREA. BETWEEN THESE TWO SYSTEMS...
A VERY WEAK AND NARROW SURFACE RIDGE WILL EXTEND THROUGH CENTRAL
NC... AND MODELS SHOW A RELATIVE MINIMUM IN QPF OVER NORTH CENTRAL
NC WITH NEUTRAL TO SINKING VERTICAL MOTION. WITH MODEL CONSENSUS ON
BETTER COVERAGE ACROSS THE SOUTH AND EVENTUALLY EASTERN CWA OVER
WHICH HIGHER PW VALUES WHERE SPREAD... HAVE PLACED GOOD CHANCE POPS
HERE WITH LOWER CHANCES IN THE NORTH... LASTING INTO THE NIGHTTIME
HOURS AS MID LEVEL HEIGHT FALLS (HOWEVER MEAGER) PERSIST. HIGHS
87-92 AND LOWS 68-72. -GIH

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 212 PM MONDAY...

THE SYNOPTIC PATTERN OVER THE CAROLINAS AND MID-ATLANTIC WED-MON
WILL BE CHARACTERIZED INITIALLY (WED) BY NW FLOW ALOFT...
TRANSITIONING (THU-MON) TO RELATIVELY LIGHT/VARIABLE FLOW ALOFT AS
THE UPPER LEVEL RIDGE OVER THE CENTRAL CONUS FLATTENS AND EXTENDS
EAST TOWARD THE CAROLINAS/SOUTHEAST. PRECIP CHANCES...I.E. THE
TIMING/LOCATION/COVERAGE OF CONVECTION...WILL BE HIGHLY DEPENDENT ON
THE EVOLUTION OF SMALL AMPLITUDE DISTURBANCES PROGRESSING SOUTHEAST
FROM THE UPPER MIDWEST/CENTRAL MS RIVER VALLEY INTO THE MID-ATLANTIC
AND CAROLINAS ON WED...WITH A POTENTIAL FOR ENHANCED COVERAGE AND
ISOLATED SEVERE WEATHER WED AFTERNOON/EVENING...THOUGH UNCERTAINTY
REMAINS ABOVE NORMAL. PRECIP CHANCES SHOULD BECOME MORE ISOLATED IN
NATURE THU-MON AS THE MAIN BELT OF WESTERLIES SHIFTS FURTHER NORTH
INTO THE MID-ATLANTIC AND FORCING BECOMES INCREASINGLY CONFINED TO
THE PIEDMONT TROUGH/SEABREEZE...MORE TYPICAL FOR THIS TIME OF YEAR.
WILL INDICATE CHANCES FOR SHOWERS/STORMS SLIGHTLY ABOVE CLIMATOLOGY
IN THE 30-40% RANGE WED...WITH A SLIGHT CHANCE (20%) PERSISTING WED
NIGHT DUE TO CONTINUED NW FLOW ALOFT. ON THU-MON WILL TREND CLOSER
TOWARD CLIMATOLOGY W/REGARD TO CHANCES FOR CONVECTION (20% DURING
THE AFTERNOON AND EARLY EVENING). TEMPERATURES WILL PRIMARILY DEPEND
ON THE EVOLUTION OF CONVECTION AND ASSOCIATED CLOUD COVER WED...WITH
1000-850 MB THICKNESSES SUGGESTING NEAR-NORMAL HIGHS AND LOWS...IN
THE UPPER 80S TO LOWER 90S AND UPPER 60S TO LOWER 70S. SLIGHTLY
ABOVE NORMAL TEMPS (LOWER/MID 90S) WILL BE POSSIBLE THU-MON GIVEN A
RELATIVELY DECREASED POTENTIAL FOR CONVECTION AND RISING HEIGHTS
(MARGINALLY) ALOFT. AT THIS TIME WILL INDICATE HIGHS NEAR OR
SLIGHTLY ABOVE CLIMATOLOGY...IN THE LOWER 90S...WITH LOWS IN THE
UPPER 60S TO LOWER 70S. -VINCENT

&&

.AVIATION /17Z MONDAY THROUGH FRIDAY/...
AS OF 1210 PM MONDAY...

VFR CONDITIONS WILL DOMINATE THIS AFTERNOON AND EVENING... WITH A
CHANCE OF MVFR OR IFR CIGS/VSBYS LATE TONIGHT INTO EARLY TUESDAY
MORNING... HOWEVER THE CONDITIONS AT INDIVIDUAL AIRPORTS WILL HINGE
ON THE PROXIMITY OF SCATTERED STORMS. THIS MORNING'S SCATTERED TO
BROKEN CLOUDS BASED BELOW 3 THOUSAND FT AGL WERE PRODUCED BY HIGH
LOW-LEVEL MOISTURE AND HIGH SURFACE DEWPOINTS POOLING TO FOCUS QUICK
DEVELOPMENT OF LOW-BASED CONVECTIVE CLOUDS WITH DAYTIME HEATING.
THESE CIGS WILL CONTINUE TO EXPAND AREALLY BUT RISE SLOWLY AND WILL
REMAIN UNIFORM VFR AT ALL FORECAST SITES. SCATTERED STORMS WILL
IMPACT FAY FIRST... ALTHOUGH ISOLATED STORMS WILL ALSO CONTINUE TO
DEVELOP NEAR RWI/RDU/GSO/INT THROUGH EARLY AFTERNOON... STEADILY
INCREASING IN NUMBER THROUGH MID TO LATE AFTERNOON. BRIEF WIND GUSTS
OVER 35 MPH ARE POSSIBLE WITH ANY OF THESE CELLS. STORMS SHOULD
REMAIN CIRCUMNAVIGABLE AT ALL SITES EXCEPT FAY... WHERE STORM
CLUSTERS ARE MORE LIKELY. BUT MOVEMENT OF STORMS IN CENTRAL NC WILL
BE DIFFICULT TO PINPOINT WITH CONVECTION APT TO DRIFT TOWARD THE
SOUTHWEST OR WEST STEERED BY THE MEAN LOW LEVEL FLOW AND/OR DRIVEN
BY OUTFLOWS. AFTER STORMS DECREASE IN NUMBER AND STRENGTH THIS
EVENING... RESIDUAL LOW LEVEL MOISTURE AND LIGHT WINDS WILL
FACILITATE IFR FOG DEVELOPMENT AND PATCHY STRATUS AREAWIDE...
ALTHOUGH INT/GSO MAY SEE A LESSER RISK OF FOG GIVEN THE SLIGHTLY
LOWER NEAR-SURFACE MOISTURE AND POSSIBLE HIGHER CLOUDS TO LIMIT
RADIATIONAL COOLING.

LOOKING BEYOND 18Z TUESDAY... ANY ADVERSE AVAIATION CONDITIONS WILL
LIFT AND MIX OUT BY MID MORNING TUESDAY. VFR CONDITIONS WILL
DOMINATE THROUGH THE END OF THE WEEK... ALTHOUGH SCATTERED STORMS
PRODUCING LOCAL BRIEF GUSTY WINDS AND MVFR CONDITIONS ARE AGAIN
ANTICIPATED TUESDAY AFTERNOON... AND WEDNESDAY AS WELL. A DECREASE
IN DAILY AFTERNOON/EARLY EVENING STORMS IS EXPECTED FOR THURSDAY
THROUGH SATURDAY AS MID LEVEL HIGH PRESSURE BEGINS TO PUSH INTO THE
AREA FROM THE WEST. -GIH

&&

.CLIMATE...
THROUGH JULY 29...THE AVERAGE MONTHLY TEMPERATURE AT KRDU IS 83.8
DEGREES. THE WARMEST JULY ON RECORD IS 83.7 DEGREES...SET JUST
LAST YEAR. CONSIDERING EXPECTED HIGHS AND LOWS OVER THE NEXT
COUPLE OF DAYS...THIS JULY SHOULD EITHER BE THE WARMEST OR JUST
SHY OF THE WARMEST JULY ON RECORD.

AT KGSO...THE AVERAGE MONTHLY TEMPERATURE THROUGH JULY 29 IS 81.5
DEGREES. THIS IS CURRENTLY THIRD WARMEST...A HALF DEGREE WARMER THAN
THE 81.0 AVERAGE TEMPERATURE OF 2011...BUT WELL BELOW THE 82.6
RECORD OF 1893. CONSIDERING EXPECTED HIGHS AND LOWS OVER THE NEXT
COUPLE OF DAYS...IT APPEARS LIKELY THAT THE AVERAGE JULY TEMPERATURE
WILL RANK IN THE TOP THREE.

&&

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

&&

SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...VINCENT
AVIATION...HARTFIELD
CLIMATE...DJF

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE RALEIGH NC
252 PM EDT MON JUL 30 2012

NCZ007>011-021>028-038>043-073>078-083>086-088-089-311200-
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-
252 PM EDT MON JUL 30 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

AN ISOLATED STRONG STORM OR TWO IS POSSIBLE FROM THE TRIANGLE
REGION TO THE SOUTH AND EAST FROM MID AFTERNOON THROUGH EARLY THIS
EVENING. LOCALLY HEAVY DOWNPOURS AND WINDS GUSTS OVER 40 MPH ARE
POSSIBLE.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

SCATTERED THUNDERSTORMS ARE EXPECTED TUESDAY AND WEDNESDAY
AFTERNOON. A FEW STORMS MAY BECOME SEVERE WITH A MAIN THREAT OF
DAMAGING WIND GUSTS.

GIH

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
335 PM EDT MON JUL 30 2012

NCZ083-084-302030-
ANSON-RICHMOND-
335 PM EDT MON JUL 30 2012

...STRONG THUNDERSTORMS WILL MOVE ACROSS RICHMOND AND ANSON COUNTIES
THROUGH 430 PM EDT...

AT 335 PM EDT...DOPPLER RADAR INDICATED STRONG THUNDERSTORMS 5 MILES
NORTHWEST OF ROCKINGHAM...MOVING WEST AT 10 MPH.

LOCATIONS IN THE PATH OF THESE STORMS INCLUDE LILESVILLE.

HAZARDS INCLUDE...
GUSTY WINDS OF 30 TO 40 MPH.
DEADLY CLOUD TO GROUND LIGHTNING
HEAVY RAIN AND MINOR FLOODING.

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.

THIS STORM WILL PRODUCE HEAVY RAINFALL...WHICH WILL CAUSE MINOR
FLOODING OF LOW LYING AREAS INCLUDING DITCHES...CREEKS...ROADWAYS AND
AREAS OF POOR DRAINAGE. AVOID THESE AREAS AND DO NOT CROSS FLOODED
ROADS. MOTORISTS SHOULD ALSO REDUCE DRIVING SPEEDS TO AVOID
HYDROPLANING.

&&

LAT...LON 3519 8028 3521 8026 3515 8022 3517 8020
      3515 8016 3519 8011 3514 8007 3514 8003
      3518 7986 3518 7968 3516 7962 3513 7958
      3506 7957 3504 7946 3499 7958 3491 7956
      3485 7963 3482 7963 3481 7966 3481 8032
TIME...MOT...LOC 1935Z 072DEG 8KT 3498 7985

ELLIS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
427 PM EDT MON JUL 30 2012

NCZ041-302115-
WAKE-
427 PM EDT MON JUL 30 2012

...STRONG THUNDERSTORMS WILL MOVE ACROSS WAKE COUNTY THROUGH 515 PM
EDT...

AT 426 PM EDT...DOPPLER RADAR INDICATED A LINE OF STRONG
THUNDERSTORMS ALONG A LINE EXTENDING FROM ROLESVILLE TO GARNER...OR
ALONG A LINE EXTENDING FROM 14 MILES SOUTHWEST OF LOUISBURG TO 11
MILES SOUTH OF RALEIGH...MOVING WEST AT 15 MPH.

LOCATIONS IN THE PATH OF THESE STORMS INCLUDE...GARNER..WAKE
FOREST..RALEIGH...FALLS LAKE...LAKE WHEELER...HOLLY
SPRINGS...AND...CARY.

HAZARDS INCLUDE...
GUSTY WINDS OF 35 TO 45 MPH.
DEADLY CLOUD TO GROUND LIGHTNING.
HEAVY RAINFALL AND MINOR FLOODING.

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.

THESE STORMS WILL PRODUCE HEAVY RAINFALL...WHICH WILL CAUSE MINOR
FLOODING OF LOW LYING AREAS INCLUDING DITCHES...CREEKS...ROADWAYS AND
AREAS OF POOR DRAINAGE. AVOID THESE AREAS AND DO NOT CROSS FLOODED
ROADS. MOTORISTS SHOULD ALSO REDUCE DRIVING SPEEDS TO AVOID
HYDROPLANING.

&&

LAT...LON 3603 7857 3598 7844 3594 7839 3593 7837
      3580 7843 3560 7860 3563 7893 3590 7879
      3595 7872 3601 7870 3603 7872 3604 7871
TIME...MOT...LOC 2026Z 099DEG 11KT 3595 7848 3565 7862

77

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