Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 091953
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
250 PM EST TUE FEB 9 2016

.SYNOPSIS... A COUPLE OF UPPER LEVEL DISTURBANCES WILL MOVE OVER THE
REGION THROUGH THIS EVENING... OTHERWISE COLD HIGH PRESSURE WILL BE
IN PLACE THROUGH MID-WEEK. THIS WILL BE FOLLOWED BY AN EVEN COLDER
ARCTIC HIGH PRESSURE FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 250 PM TUESDAY...

WITHIN A VERY DEEP UPPER TROUGH OVER THE EASTERN US...NUMEROUS
DISTURBANCES CONTINUE TO ROTATE FROM THE MIDWEST ACROSS THE CENTRAL
AND SOUTHERN APPALACHIANS. WITH THE 700MB TROUGH STILL TO OUR WEST
AND QUITE A BIT OF MOISTURE BETWEEN 850MB AND 700MB...COINCIDENT
WITH THE -12 TO -18C LAYER...THE CHANCE OF A FEW ISOLATED POCKETS OF
PRECIP WILL CONTINUE THIS AFTERNOON.  A LEAD BATCH OF SHOWERS
DEPARTING THE COASTAL PLAIN HAS REPORTEDLY BEEN ALL LIQUID (THOUGH
SOME SLEET IS LIKELY MIXING IN)...WHILE LIGHTER REFLECTIVITIES
MOVING THROUGH ALAMANCE/RANDOLPH/CHATHAM IS MOSTLY FLURRIES.  THIS
WILL CONTINUE EAST THROUGH MID AFTERNOON...WITH ANOTHER UPPER
DISTURBANCE RACING THROUGH TN THAT COULD BRING SOME ADDITIONAL LIGHT
SHOWERS/SNOW SHOWERS ACROSS THE SOUTHERN CWA THIS EVENING...THOUGH
THE GFS IS REALLY THE ONLY MODEL TO INDICATE THIS. ANY SNOW SHOWERS
OR FLURRIES WOULD BE OF NO IMPACT.  MID-LEVEL CLOUDS WILL HANG
AROUND FOR A GOOD PORTION OF THE NIGHT...POSSIBLY BEGINNING TO CLEAR
LATE...AS LOWS DIP IN THE LOW/MID 20S.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 250 PM TUESDAY...

A SHOT OF STRONG COLD ADVECTION SHOULD OFFSET DOWNSLOPE FLOW A BIT
MORE WEDNESDAY AS 850MB TEMPS ARE PROGGED TO DROP FROM -10C TO -15C
DURING THE DAY.  1000-850MB THICKNESSES ARE ALSO SET TO DROP ABOUT
30M.  WITH MORNING LOWS STARTING IN THE LOW TO MID 20S...IT SEEMS
LIKE STATISTICAL GUIDANCE MAY BE TOO WARM. DRY ADIABATIC MIXING TO
850MB USING THE NAM AND GFS WOULD SUGGEST LOWER 30S NORTHWEST TO
UPPER 30S SOUTHEAST.  CONSIDERING DOWNSLOPE FLOW...FORECAST HIGHS
WILL BE 35-41. SKIES WILL BE PARTLY CLOUDY OR EVEN MOSTLY SUNNY AS
MUCH OF THE 850-700MB MOISTURE OVER US TODAY WILL DEPART TO THE
NORTHEAST WITH THE PASSAGE OF THE MAIN 700MB TROUGH.  LOWS WEDNESDAY
NIGHT WILL BE IN THE MID TEENS TO LOWER 20S...WITH WIND CHILL VALUES
IN THE SINGLE DIGITS POSSIBLE INT HE NORTHWEST PIEDMONT.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 245 PM TUESDAY...

MAJOR NEWS IS OF COURSE THE SERIES OF IMPULSES WHICH WILL DIVE INTO
THE TROF OVER THE EASTERN CONUS AND REINFORCE THE COLD AIRMASS OVER
THE REGION THROUGH THE WEEKEND. THICKNESSES SUPPORT MINIMUM TEMPS
MOSTLY IN THE LOW AND MID 20S BOTH THURSDAY AND FRIDAY NIGHT...WITH
HIGHS BOTH DAYS IN THE UPPER 30S TO LOWER 40S. THE STRONGEST IN THE
SERIES OF SHORT WAVES WILL MOVE ACROSS THE AREA LATE FRIDAY AND
FRIDAY NIGHT...WITH AN ASSOCIATED POTENTIAL FOR WIDELY SCATTERED
SNOW SHOWERS FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING. THE
MOISTURE PROFILE IS SKINNY WITH VERY WEAK ISENTROPIC LIFT AS THE LOW
AND MID LEVEL FLOW IS PREDOMINANTLY WESTERLY...THUS IMPACTS WILL
BE NEGLIGIBLE AND OUR ONGOING SLIGHT CHANCE POPS LOOK FINE.

STRONG COLD AND DRY AIR ADVECTION WILL FOLLOW ON SATURDAY BEHIND
THIS STRONGER WAVE...SO DESPITE SUNNY SKIES....HIGHS ON SATURDAY
WILL STRUGGLE TO REACH THE MID 30S ACROSS THE NORTHERN TIER...WITH
PERHAPS SOME VERY LOW 40S ACROSS THE SOUTH. ARCTIC HIGH PRESSURE
WILL BE NEARLY OVERHEAD BY SUNDAY MORNING...AND LOOSENING OF THE
PRESSURE GRADIENT WILL ALLOW FOR STRONG RADIATIONAL COOLING. MINS
SATURDAY NIGHT WILL RANGE BETWEEN 10 DEGREES NORTH TO 15 OR 16
DEGREES ACROSS THE SOUTH...WHICH WILL PRODUCE WIND CHILLS IN THE
SINGLE DIGITS ON VALENTINES DAY (SUNDAY) MORNING. THE FRIGID AIRMASS
WILL ONLY WARM INTO THE UPPER 20S TO LOWER 30S...20 TO 25
DEGREES BELOW NORMAL...ON SUNDAY.

THE ARCTIC HIGH WILL BEGIN TO RETREAT OFF THE MID-ATLANTIC COAST
SUNDAY NIGHT AHEAD OF ANOTHER PROGRESSIVE SHORTWAVE WHICH WILL MOVE
ACROSS THE CENTRAL PLAINS. WE WILL SEE SOME SLIGHT MODERATION IN
WEAK WARM AIR AND MOISTURE ADVECTION AHEAD OF THIS WAVE ON MONDAY.
WITH THE FRIGID AND DRY AIRMASS IN PLACE...HOWEVER...THIS PRESENTS
THE POSSIBILITY OF A SHORT-LIVED COLD AIR DAMMING EVENT LATE MONDAY
INTO PERHAPS EARLY TUESDAY WHICH WOULD LIKELY FEATURE SOME P-TYPE
TRANSITION CONCERNS ACROSS THE CLIMATOLOGICALLY FAVORED PIEDMONT.
THERE IS STILL A LOT OF UNCERTAINTY AS TO JUST HOW THIS WILL PLAY
OUT DUE TO THE PROGRESSIVE NATURE OF THE FEATURES...FOR EXAMPLE THE
LATEST ECMWF SHOWS A STRONG COASTAL LOW DEVELOPING WHICH WOULD SCOUR
THE COLD AIR QUICKLY...BUT ALSO PROLONG THE EVENT AND INCREASE THE
AMOUNT OF RAIN WE MIGHT EXPECT INTO TUESDAY. AT THIS POINT WILL
INTRODUCE TUESDAY WITH CHANCE POPS EARLY AND HIGHS REACHING THE
MID TO UPPER 40S.

&&

.AVIATION /18Z TODAY THROUGH SUNDAY/...
AS OF 1240 PM TUESDAY...

A DEEP UPPER TROUGH DOMINATES THE EASTERN CONUS TODAY...WITH
DISTURBANCES ROTATING THROUGH THE UPPER TROUGH PERIODICALLY
PRODUCING SOME LIGHT SHOWERS AND CEILING NEAR 3K FT.  THE BEST
CHANCE OF MVFR CEILINGS THIS AFTERNOON WILL BE FROM KRDU
EAST...PRIMARILY AROUND TAF SITE KRWI.  WESTERLY WINDS WILL BE GUSTY
INTO THE 20-25KT RANGE...SUBSIDING TO 5-10KT TONIGHT...WHILE AREAS
OF 10K FT  ALTOCU DRIFT OVERHEAD.  THE CHANCE OF ANY PRECIP LOOKS
MUCH LESS ON WEDNESDAY AS MID-LEVEL MOISTURE DECREASES.  WEST WINDS
WILL CONTINUE...THOUGH ONLY GUSTING TO 15-20KT.

OUTLOOK...THURSDAY INTO SATURDAY WILL FEATURE MOSTLY VFR CONDITIONS
WITH GUSTY NORTHWEST WINDS OF 15-20 KTS. THE BEST CHANCE OF SUB-VFR
CONDITIONS DURING THIS PERIOD WILL BE ACROSS EASTERN NC ON FRIDAY.

&&

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


&&

$$

SYNOPSIS...BADGETT
NEAR TERM...SMITH
SHORT TERM...SMITH
LONG TERM...MLM
AVIATION...SMITH


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