Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS62 KRAH 191835
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
235 PM EDT SUN OCT 19 2014

.SYNOPSIS....HIGH PRESSURE WILL SETTLE OVER NC AND VA TONIGHT. THE
HIGH WILL DRIFT OFFSHORE MON...AHEAD OF AN UPPER LEVEL TROUGH THAT
WILL MOVE INTO OUR REGION MON NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 235 PM SUNDAY...

AN AREA OF HIGH PRESSURE AT THE SURFACE WILL SETTLE OVER CENTRAL NC
TONIGHT. THE DRY AIR ASSOCIATED WITH THIS WEATHER SYSTEM ALONG WITH
A LIGHT/CALM WIND REGIME WILL CAUSE TEMPERATURES TO PLUMMET INTO THE
40S AFTER SUNSET THEN GRADUALLY LOWER INTO THE UPPER 30S TO AROUND
40 OVERNIGHT. THE NORMALLY COLDER LOCATIONS MAY DIP INTO THE MID
30S. PATCHY FROST IS POSSIBLE WHERE TEMPS DROP BELOW 37 DEGREES. AT
THIS TIME EXPECT THE FROST TO BE VERY PATCHY AND LIGHT...LIMITED TO
ROOFTOPS AND ON THE TOPS OF CARS.

EXPECT TO SEE AN INCREASE IN HIGH CLOUDS FROM THE WEST BY MIDNIGHT
AS A WEAKENING UPPER LEVEL DISTURBANCE APPROACHES. CURRENT CIRRUS
SHIELD ASSOCIATED WITH THIS SYSTEM NOT OVERLY IMPRESSIVE...LEAVING
ONE TO WONDER IF THE GFS/ECMWF ARE TOO WET WITH THEIR RH DEPICTION
ALOFT LATER TONIGHT. THUS PLAN TO FORECAST TEMPS ON THE COOL SIDE OF
GUIDANCE IN ANTICIPATION THAT THE HIGH CLOUDS WILL BE THIN AND
PATCHY. IF THE GFS/ECMWF END UP VERIFYING...THEN MIN TEMPS MAY BE 2-
4 DEGREES WARMER THAN FORECAST AND LIGHT PATCHY FROST WILL BE OF
LITTLE CONCERN.

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
AS OF 235 PM SUNDAY...

MONDAY...SFC HIGH WILL DRIFT EAST...COMMENCING AIR MASS
MODIFICATION. LOW LEVEL RETURN EXPECTED TO BE SWLY BY AFTERNOON WITH
OCCASIONAL GUSTS AROUND 15 KTS PROBABLE. LOW LEVEL THICKNESSES
REBOUND ABOUT 10M FROM LEVELS OCCURRING THIS AFTERNOON. THIS YIELDS
MAX TEMPS 2-3 DEGREES WARMER THAN TODAY. FACTORING IN ADDITIONAL
WARMING FROM THE LOW LEVEL SW FLOW SUPPORT MAX TEMPS NEAR 70 TO THE
LOWER 70S.


MONDAY NIGHT...L/W TROUGH OVER THE EASTERN U.S. UNDERGOES
AMPLIFICATION THANKS TO A S/W CROSSING THE GREAT LAKES INTO SOUTHERN
NEW ENGLAND. THE TAILE ND OF THIS S/W WILL CROSS CENTRAL NC MONDAY
NIGHT...GENERATING AREAS OF MID-HIGH LEVEL CLOUDINESS. WARM AIR
ADVECTION IN THE 8000-15000FT LAYER MAY PRODUCE ENOUGH LIFT TO
INITIATE SOME PRECIP BUT THE SUB CLOUD LAYER STILL QUITE DRY.
THUS...EXPECT NOTHING WORSE THAN A FEW SPRINKLES...MAINLY ACROSS THE
NORTH HALF...AS THIS SYSTEM CROSSES OUR REGION. VARIABLE CLOUDINESS
AND A MODIFYING AIR MASS WILL RESULT IN MIN TEMPS SEVERAL DEGREES
WARMER COMPARED TO TONIGHT. MIN TEMPS IN THE 40S TO AROUND 50.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...

SHORTWAVE ENERGY CURRENTLY OVER THE CANADIAN ROCKIES WILL DIVE
THROUGH THE MIDWEST AND CROSS THE AREA EARLY TUESDAY...IMMEDIATELY
FOLLOWED BY ANOTHER WAVE...AND ITS ASSOCIATED COLD FRONT...DIGGING
THROUGH THE DEEPENING LONGWAVE TROUGH TUESDAY EVENING.  DURING THE
DAY...A WEST-SOUTHWESTERLY WIND AND LIMITED CLOUD COVER AHEAD OF THE
COLD FRONT WILL ALLOW TEMPS TO WARM BACK INTO THE UPPER 60S AND
LOWER 70S. AS THE COLD FRONT MOVES THROUGH TUESDAY EVENING...A SHOT
OF STRONG DCVA WILL HAVE TO OVERCOME LIMITED MOISTURE...PW BELOW
0.75"...IN ORDER TO TO SQUEAK OUT A FEW ISOLATED...LIGHT
SHOWERS...MAINLY ACROSS THE FAR NORTHERN COASTAL PLAIN WHERE
MOISTURE PROFILES ARE SLIGHTLY MORE CONDUCIVE FOR PRECIP.
HOWEVER...MODELS ARE ONLY GENERATING A HUNDREDTH OR TWO OF QPF IN
SPOTS...SO SLIGHT CHANCE POPS CONTINUE TO BE THE BEST BET.

BEHIND THE FRONT...A NORTHWESTERLY WIND WILL PERSIST THROUGH MOST OF
THE WEEK AS THE UPPER TROUGH CLOSES OFF INTO AN UPPER LOW OVER THE
MID-ATLANTIC COAST.  MODELS HAVE HINTED AT A FEW SHOWERS ON
WEDNESDAY AFTERNOON AS THE CORE OF THE COLD AIR ALOFT AND SOME VERY
WEAK INSTABILITY DEVELOPS.  HOWEVER...MOISTURE WILL STILL EB
SEVERELY LACKING AND JUST ENHANCE CLOUD COVER SEEMS MORE LIKELY.
THICKNESSES ARE FORECAST TO BRIEFLY TOUCH 1340M ON WEDNESDAY
MORNING...THEN CLIMB BACK TOWARD NORMAL VALUES AROUND 1360M BY THE
END OF THE WEEK AS THE UPPER BEGINS TO DRIFT NORTHEAST AWAY FROM THE
REGION.  THUS...HIGHS WILL BE COOLEST WEDNESDAY IN THE LOW TO MID
60S AND TREND BACK INTO THE UPPER 60S TO LOWER 70S.

THERE ARE SIGNIFICANT MODEL DIFFERENCES BY NEXT WEEKEND AS ENERGY
CROSSING THE CENTRAL US IS FORCED INTO THE DEEP SOUTH AND THEN
EITHER MOVES EAST ACROSS THE SOUTHEAST US (GFS SOLUTION) OR CUTS OFF
OVER THE GULF COAST (ECMWF SOLUTION).  WPC HAS A STRONG PREFERENCE
FOR THE ECMWF AND ITS ENSEMBLE MEAN.  EITHER WAY THE FORECAST WILL
REMAIN DRY AND NEAR NORMAL THROUGH THE END OF THE EXTENDED PERIOD.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 135 PM SUNDAY...

A DRY AND STABLE AIR MASS OVER CENTRAL NC WILL RESULT IN VFR
CONDITIONS THROUGH TUESDAY. AN AREA OF HIGH PRESSURE WILL SETTLE
OVERHEAD TONIGHT THEN DRIFT EAST ON MONDAY. RETURN SLY FLOW WILL
BEGIN TO ADVECT LOW LEVEL MOISTURE INTO OUR REGION...RESULTING IN
SCATTERED CUMULUS...MAINLY IN VICINITY OF KFAY.

THRE IS A GOOD CHANCE THAT VFR CONDITIONS WILL PREVAIL TUESDAY
THROUGH FRIDAY. A SERIES OF S/W ROTATING AROUND A CLOSED UPPER LEVEL
LOW OVER THE NORTHERN MID ATLANTIC WILL CAUSE PERIODS OF CLOUDINESS
OVER CENTRAL NC TUESDAY THROUGH WEDNESDAY NIGHT. HOWEVER CLOUD BASES
SHOULD REMAIN ABOVE MVFR CRITERIA. THE UPPER LEVEL LOW WILL LIFT
GRADUALLY NEWD THU INTO FRIDAY...ALLOWING HIGH PRESSURE TO BUILD INTO
OUR REGION.

&&

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

&&

$$

SYNOPSIS...WSS/MWS
NEAR TERM...WSS
SHORT TERM...WSS
LONG TERM...BLS
AVIATION...WSS


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.