National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 142343
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
743 PM EDT FRI JUN 14 2013

.SYNOPSIS...
HIGH PRESSURE OVER THE GREAT LAKES WILL BUILD SOUTH AND EAST INTO
THE MID ATLANTIC ON SATURDAY AND THEN OFF OFF THE COAST ON SUNDAY.
A SOUTHERLY FLOW WILL DEVELOP ON SUNDAY AND CONTINUE INTO EARLY NEXT
WEEK AS A COLD FRONT APPROACHES THE REGION FROM THE NORTHWEST ON
MONDAY AND TUESDAY.
&&

.NEAR TERM /TODAY AND TONIGHT/...
-- Changed Discussion --
AS OF 300 PM FRIDAY...

LATEST WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL TROUGH AXIS
SHIFTING ACROSS SOUTHEASTERN VA AND EASTERN NC THIS AFTERNOON. A
MUCH DRIER AND MORE STABLE AIR MASS HAS MOVED INTO THE REGION WITH
TEMPERATURES IN THE MID 70S TO AROUND 80 WITH DEWPOINTS IN THE LOWER
TO MID 50S. VISIBLE SATELLITE IMAGERY SHOWS A LARGE FIELD OF FAIR
WEATHER CUMULUS ACROSS THE REGION WITH THE GREATEST COVERAGE AND
VERTICAL GROWTH ACROSS THE COASTAL PLAIN AND NORTHEAST PIEDMONT.
HIGH RES CONVECTION ALLOWING MODELS NOTE THAT A SHOWER OR TWO COULD
DEVELOP ACROSS SOUTHERN VA THIS AFTERNOON AND DRIFT INTO NORTHERN NC
BEFORE DISSIPATING BEFORE SUNSET. LATEST SPC MESOANALYSIS SHOWS VERY
LITTLE INSTABILITY ACROSS CENTRAL NC WITH SOME MEAGER BUT STILL WEAK
INSTABILITY ON THE ORDER OF 250 J/KG OF MLCAPE ACROSS WESTERN VA.
WHILE THIS AREA HAS EVEN LESS LOW LEVEL MOISTURE THAN LOCATIONS
FURTHER EAST...THE MID LEVEL CAP ACROSS EASTERN NC IS LESS
PRONOUNCED IN THE WEST WHICH COULD ALLOW A ROGUE SHOWER TO DEVELOP.
BUT WE STILL THINK IT WILL BE HARD TO GET MUCH CONVECTION GOING IN A
REGION OF LARGE SCALE DESCENT AND LIMITED MOISTURE SO WILL OPT TO
KEEP THE FORECAST DRY WITH POPS BELOW 10 PERCENT.

FAIR WEATHER IS EXPECTED OVERNIGHT WITH A FEW PATCHES OF MID/LOW
LEVEL CLOUDS POSSIBLE...ESPECIALLY IN THE WESTERN PIEDMONT.
STILL...EXPECT MOSTLY CLEAR SKIES WITH A LIGHT AND VARIABLE WIND
COMPLEMENTING LOWS IN THE UPPER 50S TO LOWER 60S. -BLAES
-- End Changed Discussion --
&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 300 PM FRIDAY...

THE UPPER LEVEL TROUGH WILL CONTINUE TO PUSH FURTHER OFFSHORE ON
SATURDAY WITH THE NORTHWEST FLOW ALOFT BECOMING MORE ZONAL ON
SATURDAY NIGHT. THE SURFACE HIGH WILL SHIFT SOUTHEAST ACROSS THE
REGION EARLY SATURDAY AND WILL BE LOCATED OFFSHORE BY SATURDAY
AFTERNOON. FAIR WEATHER IS EXPECTED DURING THE PERIOD BUT A SHALLOW
LAYER OF MOISTURE IS PROGGED TO BE TRAPPED BELOW A STRENGTHENING
SUBSIDENCE INVERSION AND RESULT IN THE DEVELOPMENT OF FLAT CUMULUS
CLOUDS DURING THE LATE MORNING AND AFTERNOON WITH MOSTLY TO PARTLY
SUNNY SKIES. THE DIURNALLY DRIVEN CLOUDS WILL ABATE DURING THE
EVENING ON SATURDAY BUT SOME MID LEVEL CLOUDINESS WILL MOVE INTO THE
AREA FROM THE WEST LATE SATURDAY NIGHT IN A WARM ADVECTION PATTERN.
HIGHS ON SATURDAY WILL RANGE IN THE 83 TO 88 RANGE WITH OVERNIGHT
LOWS IN THE MID 60S. -BLAES

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 250 PM FRIDAY...

A BROAD UPPER TROUGH OVER THE EASTERN TWO-THIRDS OF THE NATION WILL
GRADUALLY AMPLIFY THIS PERIOD AS AN UPPER RIDGE BUILDS OVER THE
SOUTHERN PLAINS INTO THE ROCKIES. A SERIES OF S/WS IN THE DEVELOPING
W-NW FLOW ALOFT WILL BRING A THREAT FOR SHOWERS AND T-STORMS TO THE
REGION EARLY NEXT AND AGAIN LATE IN THE WEEK. THE MAIN WEATHER
HEADLINE FOR NEXT WEEK WILL BE THE GOOD PROBABILITY OF MAX TEMPS 4-7
DEGREES BELOW NORMAL FOR THE THIRD WEEK IN JUNE. THE UPPER LEVEL JET
FORECAST TO BE FARTHER SOUTH THAN NORMAL FOR THIS TIME OF YEAR. THIS
SWD POSITION WILL ALLOW COOLER CANADIAN AIR TO SPILL INTO THE
NORTHERN THIRD OF THE U.S. WITH SOME RESIDUAL AFFECTS BEING FELT IN
THE CAROLINAS.

SUNDAY...SURFACE HIGH OVER THE REGION EARLY IN THE DAY WILL MOVE
OFFSHORE. THE RESULTANT SLY FLOW ON THE BACK SIDE OF THE HIGH WILL
ADVECT WARM MOIST AIR INTO THE PIEDMONT BY AFTERNOON-EARLY EVENING.
IT APPEARS THAT ANY CONVECTION THAT DEVELOPS IN THE HIGHER TERRAIN
OF WESTERN NC WILL STAY JUST EAST OF THE PIEDMONT AS STEERING FLOW
SHOULD KEEP THE CONVECTION PARALLEL TO THE RIDGES. LOW LEVEL
THICKNESSES FAIRLY CLOSE TO NORMAL WHICH SUGGEST AFTERNOON TEMPS
SOLIDLY IN THE MID 80S.

MONDAY THROUGH TUESDAY...THE FIRST S/W IN THE W-NW FLOW ADVANCES
TOWARD OUR REGION MONDAY...AND EXITS THE REGION TUESDAY. THE
ASSOCIATED COLD FRONT WILL ENHANCE LOW LEVEL CONVERGENCE WHILE THE
SYSTEM ALOFT SUPPLIES ADDED LIFT. WITH PRECIP WATER VALUES PROJECTED
TO BE 1.75-1.9 INCHES...EXPECT SCATTERED TO NUMEROUS SHOWERS AND A
FEW THUNDERSTORMS WITH THIS SYSTEM...MAINLY IN THE WEST LATE MONDAY
AND AREAWIDE MONDAY NIGHT INTO TUESDAY. IF LATER MODEL GUIDANCE
REMAINS CONSISTENT...WILL NEED TO INCREASE POPS TO LIKELY OR LOW END
CATEGORICAL MONDAY NIGHT INTO TUESDAY.

WEDNESDAY THROUGH THURSDAY SHOULD SEE A RELATIVELY TRANQUIL WEATHER
PATTERN AS HIGH PRESSURE OVER THE LOWER GREAT LAKES NOSES SEWD INTO
OUR REGION. DEVELOPING ELY FLOW BY THURSDAY MAY ADVECT ATLANTIC
MOISTURE INTO CENTRAL NC RESULTING IN CONSIDERABLE CLOUDINESS.

MODEL GUIDANCE DIFFERS LATE IN THE WEEK AS THE GFS IS MUCH MORE
PROGRESSIVE WITH AN UPPER LEVEL CROSSING THE PACIFIC NW INTO THE
NORTHERN ROCKIES WHILE THE ECMWF IS SLOWER WITH THIS EWD
TRANSLATION DUE TO PRESENCE OF UPPER RIDGE OVER THE ROCKIES/HIGH
PLAIN. SINCE GFS HAS A HISTORY OF BEING TOO FAST IN THIS TYPE OF
PATTERN...PREFER THE ECMWF SOLUTION. THIS MODEL CHOICE SUGGEST
ANOTHER S/W APPROACHING CENTRAL NC BY FRIDAY. MOISTURE ADVECTION
AHEAD OF THIS SYSTEM MAY CAUSE A THREAT FOR LIGHT RAIN SHOWERS BY
THE END OF THE WEEK. DUE TO LIKELY MODEL ADJUSTMENTS IN TIMING OR
STRENGTH OF THE SYSTEM...PREFER TO KEEP POPS AT OR BELOW 20 PERCENT
FOR FRIDAY.
&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
AS OF 740 PM FRIDAY...

24-HR TAF PERIOD...
HIGH PRESSURE WILL BUILD INTO CENTRAL NC FROM THE NORTH TONIGHT AND
ACROSS THE AREA ON SATURDAY... RESULTING IN A HIGH CONFIDENCE OF VFR
CONDITIONS THROUGH THE 24 HOUR TAF PERIOD. ANY CLOUD COVER (MOSTLY
SATURDAY AFTERNOON) WILL REMAIN VFR IN THE 5-6 KFT RANGE THROUGH THE
PERIOD... WITH LIGHT AND VARIABLE TO CALM WINDS TONIGHT BECOMING
WEST-SOUTHWEST TO SOUTHWESTERLY ON SATURDAY IN THE 5 TO 10 KT RANGE.

LOOKING FURTHER AHEAD...
HIGH PRESSURE JUST OFF THE SOUTHEAST COAST SHOULD PRODUCE FAIR
WEATHER ACROSS CENTRAL NC ON SUNDAY. AS THE FRONT MOVES FURTHER
OFFSHORE ON SUNDAY NIGHT...THE THREAT OF SHOWERS OR THUNDERSTORMS
WILL GROW IN AN INCREASINGLY MOIST PATTERN FROM SUNDAY EVENING
THROUGH TUESDAY WITH AN IMPROVING TREND ON WEDNESDAY. THE SHOWERS
AND STORMS WILL BE MOST NUMEROUS DURING THE AFT/EVE HOURS ON MONDAY
AND TUESDAY. -BLAES
-- End Changed Discussion --
&&

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

&&

$$

SYNOPSIS...BLAES
NEAR TERM...BLAES
SHORT TERM...BLAES
LONG TERM...WSS
AVIATION...BSD/BLAES