Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 010719
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
318 AM EDT SAT NOV 1 2014

.SYNOPSIS...AS AN UPPER-LEVEL LOW MOVES THROUGH THE CAROLINAS
TODAY...SURFACE LOW PRESSURE INTENSIFIES JUST OFF THE CAROLINA
COAST. AS THE SURFACE LOW MOVES TOWARD THE CANADIAN MARITIMES
SUNDAY...HIGH PRESSURE BUILDS OVER THE REGION. HIGH PRESSURE REMAINS
OVER THE REGION THROUGH EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 315 AM SATURDAY...

THE LATEST SURFACE ANALYSIS INDICATED BAGGY LOW PRESSURE OVER THE
CAROLINAS AS THE UPPER LOW MOVED SOUTH-SOUTHEAST INTO THE TENNESSEE
VALLEY ON WATER VAPOR IMAGERY. AREAS OF RAIN WERE NOTED OVER CENTRAL
NORTH CAROLINA FROM THE TRIANGLE AND FAYETTEVILLE WEST ACROSS THE
YADKIN RIVER. SEVERAL FORECAST CHALLENGES EXIST FOR THE DAY...
INCLUDING...

WIND...THE GRADIENT WILL TIGHTEN LATER TODAY AS THE UPPER LOW MOVES
THROUGH THE CAROLINAS AND SURFACE LOW PRESSURE DEEPENS OFFSHORE. THE
GFS FORECASTS...BY LATE AFTERNOON...WINDS AT 925MB TO 850MB IN
VICINITY OF 50KT. THE RAP AND THE NAM ARE...ON AVERAGE...AT LEAST
10KT LESS. CONSIDERED A WIND ADVISORY FOR LATER TODAY INTO THIS
EVENING...BUT WITH CLOUDS EXPECTED TO LINGER AT LEAST INTO THE
EVENING...MIXING OF THE HIGHER WINDS MAY BE DIFFICULT...AND ONCE
SKIES START TO CLEAR ON BUFR SOUNDINGS THE LOW-LEVEL LAPSE RATES ARE
NOT AS STEEP. STATISTICAL GUIDANCE IS ALSO NOT QUITE AT THE LEVELS
ONE WOULD LOOK FOR IN TERMS OF WIND ADVISORY CRITERIA. LATE THIS
AFTERNOON INTO THIS EVENING AS THE GRADIENT TIGHTENS AND SOME
CLEARING BEGINS LATER...ANTICIPATE SOME WINDS AT TIMES BRIEFLY
NEAR...OR JUST ABOVE...30KT. COORDINATED WITH ADJACENT OFFICES AND
HAVE OPTED TO HOLD OFF ON ANY WIND ADVISORY FOR NOW.

PRECIPITATION CHANCES...ANTICIPATE WIDESPREAD RAIN ESPECIALLY OVER
THE WESTERN PIEDMONT THIS MORNING...THEN AS THE UPPER LOW MOVES
SOUTHEAST THERE MAY BE SOME MID-LEVEL DRIER AIR MOVING OVER PARTS OF
CENTRAL NORTH CAROLINA FROM THE EAST ALONG AND NORTH OF U.S. 64
WHICH MAY MAKE FOR DIMINISHING OR SCATTERING OF AREAS OF RAIN FOR A
TIME THERE. LATER...MOISTURE WRAPPING AROUND THE UPPER LOW SHOULD
PIVOT BACK OVER CENTRAL NORTH CAROLINA LEADING TO MORE NUMEROUS
AREAS OF RAIN BEFORE CLEARING TAKES PLACE QUICKLY FROM THE WEST VERY
LATE THIS AFTERNOON THROUGH THE EVENING. FOR THIS FORECAST...HAVE
CONDITIONS DRY IN CENTRAL NORTH CAROLINA BY 03Z...THOUGH IN THE
FARTHEST EAST PORTIONS THERE MAY BE A PATCH OR TWO OF RAIN LINGERING
JUST SLIGHTLY THEREAFTER...THOUGH NOT MUCH AS GFS AND NAM BUFR
SOUNDINGS QUICKLY DRY TONIGHT. AS OF THIS WRITING THE HIGHEST QPF
SHOULD BE IN THE WESTERN PIEDMONT THIS MORNING THEN SHIFTING SOUTH
ACROSS THE SOUTHWEST PIEDMONT...SANDHILLS...AND SOUTHERN COASTAL
PLAIN THIS AFTERNOON WHERE THE GREATEST LIFT IS FORECAST ON THE
NORTHERN PERIPHERY OF THE UPPER LOW...AND CLOSER TO THE STRONG 300MB
AND 500MB JETS.

OUTSIDE OF ANY CELL THAT MAY GET STRONG ENOUGH FOR A HINT OF
GRAUPEL...PRECIPITATION TYPE SHOULD BE LIQUID. PARTIAL THICKNESSES
REMAIN IN THE LIQUID RANGE OR ON THE EDGE OF INDETERMINATE...WHICH
USUALLY MEANS RAIN WITH A WARM BOUNDARY LAYER. BUFR SOUNDINGS SHOW
AN ABOVE FREEZING DEPTH THAT IS TOO HIGH FOR ANYTHING OTHER THAN
LIQUID...MOSTLY AOA 3000FT.

CHANCE FOR THUNDER...BUFR SOUNDINGS HAVE THE STEEPEST LOW-LEVEL
LAPSE RATES EARLY THIS MORNING. LAPSE RATES EVEN IN THE LOW LEVELS
ESSENTIALLY WARM TO MOIST ADIABATIC BY 15Z OR SO. WHILE LIFTED
INDICES FALL TO JUST ABOVE 0C DURING THE DAY...0-3KM COMPUTED CAPE
DOES NOT REGISTER ON THE GFS. AS OF THIS WRITING THE STRONGER ECHOES
IN CENTRAL NORTH CAROLINA WERE NOT PRODUCING THUNDER...AND WHILE A
RUMBLE OR TWO IS POSSIBLE...AND EVEN A HINT OF GRAUPEL...FOR THIS
FORECAST WILL LEAVE OUT THE MENTION OF THUNDER. SPC GENERAL THUNDER
IS EAST OF CENTRAL NORTH CAROLINA WHICH SEEMS REASONABLE.

TEMPERATURES...LEANED TOWARD THE COOLER MOS GUIDANCE VALUES OR A
BLEND...BASED ON ALREADY WARM TEMPERATURES OR WARMING TEMPERATURES
WITH CLOUDS AND POSSIBLE BREAKS IN SOME PRECIPITATION IN PLACES. NOT
MUCH OF A RISE ANTICIPATED TOWARD THE YADKIN RIVER...46 TO 51...TO
MOSTLY MID 50S FROM KFAY TO KRWI. THE TEMPERATURE HAS ALREADY WARMED
ABOVE THE RECORD LOW MAX AT KFAY...AND WILL BE AT LEAST A DEGREE
ABOVE THE RECORD LOW MAX AT KGSO. CHILLY DAY FOR THE FIRST OF
NOVEMBER...THOUGH.

TONIGHT...COLD AIR ADVECTION IS STRONG...AND WHILE WINDS SHOULD BE
UP THROUGHOUT THE NIGHT HELPING TO CONTINUE MIXING...THE DEGREE OF
COLD AIR MOVING INTO CENTRAL NORTH CAROLINA CANNOT BE IGNORED.
BRIEFLY CONSIDERED THE MENTION OF A FREEZE TONIGHT IN WESTERN PARTS
OF CENTRAL NORTH CAROLINA...AND WHILE IT IS POSSIBLE ON AN ISOLATED
BASIS...THINK THAT MOST LOCATIONS WILL HAVE LOWS A DEGREE OR TWO
ABOVE FREEZING WITH AN ISOLATED LOCATION OR THREE IN SHELTERED SPOTS
BRIEFLY A TOUCH COLDER. MID TO UPPER 30S IN THE COASTAL PLAIN WHERE
CLOUDS LINGER LONGER AND STRONG COLD AIR ADVECTION ARRIVES LATER.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM SATURDAY...

SUNDAY AND SUNDAY NIGHT... DEEP LOW PRESSURE SYSTEM OFF THE NEW
ENGLAND COAST GRADUALLY LIFTS N-NE SUNDAY...ALLOWING A CANADIAN HIGH
PRESSURE SYSTEM TO BUILD INTO THE CAROLINAS. PRESSURE GRADIENT
REMAINS RATHER TIGHT EARLY SUNDAY SO EXPECT WIND GUSTS AROUND 25-30
MPH FOR THE FIRST HALF OF SUNDAY. AS THE HIGH BECOMES THE MORE
DOMINANT PLAYER BY SUNDAY AFTERNOON...GUSTS WILL BECOME WEAKER AND
LESS FREQUENT. THICKNESSES SUNDAY AFTERNOON AVERAGE 40-50M BELOW
NORMAL FOR EARLY NOVEMBER...TRANSLATING TO HIGH TEMPS A GOOD 15
DEGREES BELOW NORMAL. THIS YIELDS MAX TEMPS IN THE 50-55 DEGREE
RANGE SUNDAY AFTERNOON.

SFC HIGH PRESSURE SETTLES OVERHEAD SUNDAY NIGHT. SFC WINDS SHOULD
DECOUPLE PRIOR TO MIDNIGHT. UNDER CLEAR SKIES AND LIGHT/CALM WIND
REGIME IN THE CHILLY AIR MASS...APPEARS A GOOD LIKELIHOOD OF A
SEASON ENDING FREEZE BY EARLY MONDAY MORNING. CONSIDERING THE
MAGNITUDE OF THE COLD AIR CURRENTLY SPILLING SOUTHWARD ACROSS THE
LOWER OH AND TN VALLEYS (TEMPS APPROACHING FREEZING NEAR THE OH
RIVER AT 2 AM)...POTENTIAL FOR THE NORMALLY COLDER LOCATIONS TO DROP
INTO THE MID-UPPER 20S BY EARLY MONDAY WITH THE REMAINDER OF THE
REGION NEAR 30 DEGREES. THE CAVEAT TO SUNDAY NIGHT IS THAT SOME OF
THE MODEL GUIDANCE(SPECIFICALLY THE NAM) IS HINTING AT THE POTENTIAL
FOR SOME OROGRAPHIC CLOUDINESS TO OCCUR...MAINLY OVER THE WESTERN-NW
PIEDMONT. IF THIS WERE TO VERIFY...STILL BELIEVE THAT IT WILL BE
OPAQUE ENOUGH TO NOT AFFECT OVERNIGHT TEMPS.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 300 AM SATURDAY...

MONDAY THROUGH TUESDAY NIGHT... AIR MASS MODERATES AS S/W RIDGE AND
ATTENDANT SFC RIDGE MAINTAINS MOSTLY CLEAR SKIES. POSITION FO TEH
SFC RIDGE TO OUR SOUTH WILL PROMOTE A WLY LOW LEVEL FLOW MONDAY
AFTERNOON. THIS SLIGHT DOWNSLOPE COMPONENT TO THE WIND WILL AID IN
THE AIR MASS MODIFICATION. AFTER A  CHILLY START TO THE DAY...SHOULD
SEE TEMPS REBOUND INTO THE 60-65 DEGREE RANGE BY AFTERNOON. THOUGH
NOT AS CHILLY AS SUNDAY NIGHT...AND LIGHT WIND REGIME AND MOSTLY
CLEAR SKIES WILL ALLOW TEMPS TO DROP BACK INTO THE 30S MONDAY NIGHT.
FOR TUESDAY...THE SFC RIDGE PROJECTED TO DRIFT EAST WITH A WEAK
RETURN FLOW IN ITS WAKE. TEMPS SHOULD RECOVER TO NEAR NORMAL LEVELS
(MID 60S-NEAR 70). LOWS TUESDAY NIGHT IN THE LOW-MID 40S.

WEDNESDAY THROUGH FRIDAY... A SERIES OF S/WS IN THE NORTHERN STREAM
WILL SERVE TO AMPLIFY THE L/WROUGH OVER THE EASTERN U.S. BY THE END
OF THE WORK WEEK. THESE S/WS WILL PROPEL A SFC FRONT SEWD ACROSS
CENTRAL NC THURSDAY. LOW LEVEL INFLOW OFF OF THE ATLANTIC AND THE
GULF IS ESSENTIALLY CUT-OFF SO SYSTEM WILL HAVE TO BRING ITS ON
MOISTURE WITH IT. CONSIDERING THE DEPTH OF THE DRY AIR EXPECTED WITH
THE EARLY WEEK CANADIAN HIGH....SYSTEM WILL LIKELY BE MOISTURE
STARVED ONCE IT GETS TO CENTRAL NC. THUS...NOT EXPECTING MUCH IN THE
WAY OF AMOUNTS WITH THIS SYSTEM. CURRENT FORECAST OF 20 PERCENT
LOOKS SUFFICIENT AT THIS TIME. PRE-FRONTAL WARMING ON WEDNESDAY
SHOULD PUSH AFTERNOON TEMPS TO NEAR 70 NW AND LOWER 70S ELSEWHERE.
IF CLOUDS FAIL TO THICKEN/LOWER WEDNESDAY AFTERNOON...MAX TEMPS MAY
END UP BEING A FEW DEGREES WARMER THAN CURRENTLY FORECAST. EXTENT OF
CLOUDS AND SHOWERS WILL DETERMINE MAX TEMPS THURSDAY WITH MORE
CLOUDS/SHOWERS LEADING TO COOLER TEMPS. CANADIAN HIGH PRESSURE WILL
BUILD INTO THE SE U.S. FRIDAY IN THE WAKE OF THE DEPARTING COLD
FRONT...SENDING TEMPS BACK BELOW NORMAL.

&&

.CLIMATE...

RECORD LO-MAX TEMPERATURES FOR NOVEMBER 1ST

        LO-MAX

RDU     50/1925
GSO     45/1925
FAY     48/1988

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 155 AM SATURDAY...

THROUGH THE 06Z VALID TAF PERIOD...AREAS OF RAIN AND WITH THEM
MOSTLY MVFR CONDITIONS ARE EXPECTED...ALTHOUGH THERE WILL BE SOME
SCATTERED IFR CONDITIONS IN EITHER LOWER CEILINGS OR BRIEFLY LOWER
VISIBILITIES. OUTSIDE OF RAIN CONDITIONS SHOULD BE MOSTLY VFR. TAFS
WILL REFLECT MVFR CONDITIONS FOR THE MOST PART OR CONDITIONS
DETERIORATING TO MVFR...WITH THE LATER AVIATION HAZARD TODAY INTO
TONIGHT BEING THE WIND. SURFACE WINDS SHOULD INCREASE DURING THE DAY
AND BY LATE TODAY EXPECT A FEW GUSTS IN VICINITY OF 30KT. NOT FAR
OFF OF THE SURFACE...THE GFS MODEL MORE SO THAN THE NAM FORECASTS
WINDS BY 2000FT CLOSING IN ON 50KT. REGARDLESS...AVIATION INTERESTS
SHOULD BE PREPARED FOR GUSTY CONDITIONS AT AND OFF OF THE SURFACE.
PRECIPITATION SHOULD BE EAST OF CENTRAL NORTH CAROLINA BY 03Z WITH
GRADUALLY CLEARING CONDITIONS FROM THE WEST.

BEYOND THE 06Z VALID TAF PERIOD...VFR CONDITIONS ARE EXPECTED. THE
SURFACE GRADIENT GRADUALLY RELAXES AND GUSTINESS IN THE WIND SHOULD
GRADUALLY RELAX AS WELL ON SUNDAY. AN INITIAL COLD FRONT IS FORECAST
TO WEAKEN AS IT APPROACHES CENTRAL NORTH CAROLINA WEDNESDAY...AND
CURRENTLY IT APPEARS THE THREAT OF ANY LATE NIGHT AND EARLY MORNING
LOW CLOUDS SHOULD BE BEYOND WEDNESDAY.

&&

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

&&

$$

SYNOPSIS...DJF
NEAR TERM...DJF
SHORT TERM...WSS
LONG TERM...WSS
CLIMATE...CBL
AVIATION...DJF



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