Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 131501
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1000 AM EST SAT FEB 13 2016

.SYNOPSIS...ARCTIC HIGH PRESSURE WILL BUILD INTO CENTRAL NC TODAY
AND SUNDAY. AN AREA OF LOW PRESSURE WILL APPROACH FROM THE WEST ON
MONDAY AND CROSS THE REGION MONDAY NIGHT AND TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM SATURDAY...

 VERY COLD AND DRY ARCTIC AIRMASS FILTERING INTO CENTRAL NC VIA
STRONG COLD AIR ADVECTION CURRENTLY TAKING PLACE OVER MUCH OF THE
MID-ATLANTIC REGION. FAIRLY GOOD TEMPERATURE GRADIENT CURRENTLY IN
PLACE FROM NORTH TO SOUTH ACROSS THE CWA WITH MID 20S STILL IN THE
NORTH BUT AROUND FREEZING IN THE SOUTH. THIS GRADIENT WILL CONTINUE
TODAY WITH HIGHS IN THE LOW 30S NORTH TO UPPER 30S TO NEAR 40
DEGREES ACROSS THE SOUTH. ASIDE FROM THE COLD...THE WEATHER STORY OF
THE DAY WILL BE THE WINDS WITH A FEW GUSTS ALREADY OBSERVED TO BE
BETWEEN 25-30 KTS. THIS WILL CONTINUE THROUGH THE MORNING AND INTO
THE EARLY AFTERNOON BUT MAY BECOME MORE OF A HIGH SUSTAINED WIND IN
THE 15-20 KT RANGE. COMBINING THE WINDS AND THE COLD WE EXPECT TO
HAVE WIND CHILL VALUES IN THE MID 20S ACROSS MUCH OF THE AREA WITH A
FEW LOW 30S IN THE SOUTH. DESPITE THE COLD...WITH HIGH PRESSURE
OVERHEAD...EXPECT MOSTLY CLEAR SKIES FOR MUCH OF THE DAY.

FOR TONIGHT...THICKNESSES PLUNGE INTO THE 1230-1240 METER
RANGE...INDICATIVE OF THE POSSIBILITY OF SOME SINGLE DIGIT
TEMPERATURES...HOWEVER WITH WINDS STIRRING FOR MUCH OF THE
NIGHT...LOWS IN THE LOW TO MID TEENS SEEMS MORE LIKELY WITH A FEW
SINGLE DIGITS POSSIBLE IN RURAL AREAS. WINDS SHOULD RELAX FOR THE
MOST PART OVERNIGHT BUT STILL WIND CHILLS IN THE LOWER SINGLE DIGITS
APPROACHING ZERO ARE NOT OUT OF THE QUESTION.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 340 AM SATURDAY...

L/W TROUGH OVER THE EASTERN U.S. RELOADS AS A
POTENT S/W DIGS SEWD FROM THE NORTHERN PLAINS INTO THE GREAT LAKES.
THIS WILL BACK THE UPPER LEVEL FLOW OVER THE CAROLINAS..AND ADVECT
HIGH LEVEL MOISTURE INTO OUR REGION BY LATE IN THE DAY. AT THE
SURFACE...SFC HIGH DRIFTS OFFSHORE...INITIATING RETURN LOW LEVEL
FLOW. THUS MOSTLY-PARTLY SUNNY SKIES IN THE MORNING WILL GIVE WAY TO
THICKENING CLOUD COVER IN THE AFTERNOON. AFTERNOON TEMPS REMAIN WELL
BELOW NORMAL...RANGING FROM NEAR 30 NORTH TO THE MID 30S SW.

INCREASING ISENTROPIC UPGLIDE IN THE LOW LEVEL WAA PATTERN COUPLED
WITH INCREASING DIVERGENCE ALOFT AHEAD OF THE APPROACHING S/W WILL
INCREASE LIFT THROUGH THE COLUMN. THE LIFT APPEARS SUFFICIENT TO
GENERATE PRECIPITATION OVER OUR WESTERN PIEDMONT LATE SUNDAY NIGHT.
THERMAL PROFILES SUGGEST THAT PRECIP SHOULD INITIALLY START OUT AS
FROZEN PRECIP (SNOW OR SNOW/SLEET MIX). PRECIP FALLING THROUGH DRY
SUB CLOUD SHOULD TRIGGER A HYBRID/IN-SITU DAMMING EVENT OVER THE NW
PIEDMONT. LOCKING THIS COLDER AIR IN PLACE SUGGEST A BETTER
POTENTIAL FOR A LIGHT ACCUMULATION ACROSS THE NW PIEDMONT/TRIAD
REGION BEFORE DAYBREAK MONDAY. MIN TEMPS LOW-MID 20S.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 4 AM SATURDAY...

...STORM SYSTEM LIKELY TO BRING WINTRY WEATHER THREAT SUN NIGHT/MON
FOLLOWED BY HEAVY RAIN THREAT AND A FEW STORMS MON NIGHT/TUE...

MONDAY THROUGH TUESDAY: S/W ENERGY ALOFT IS FORECAST TO DIG
SOUTHEASTWARD FROM THE CENTRAL/SOUTHERN PLAINS SUNDAY NIGHT INTO
MONDAY AND AMPLIFY ACROSS THE DEEP SOUTH...WITH A DEVELOPING SURFACE
LOW. THE GFS AND ECMWF CONTINUE TO BE FURTHER WEST WITH THE TRACK OF
THE SURFACE LOW COMPARED TO THE CANADIAN AND THE NAM (WITH GFS/ECMWF
SHOWING LESS/WEAKER WINTER STORM). WILL CONTINUE TO TREND TO THE
PREFERRED GFS... WHICH IS SIMILAR TO THE LATEST ECMWF. THIS WILL
YIELD AN INSITU COLD AIR DAMMING EVENT FOR MONDAY... WITH GENERALLY
LIGHT PRECIP. HOWEVER... GIVEN THE ANTECEDENT ARCTIC AIRMASS IN
PLACE OVER CENTRAL NC ON SUNDAY... WE WILL LIKELY SEE A LIGHT WINTRY
MIX ACROSS MOST/IF NOT ALL OF CENTRAL NC ON MONDAY MORNING... WITH A
TRANSITION TO RAIN FROM SE TO NW THROUGHOUT THE DAY. THERE CONTINUES
TO BE A LOT OF DISAGREEMENT WITH REGARD TO HOW FAST WARM AIR ABOVE
THE COLD DOME WILL SURGE IN AND TURN ANY LIGHT PRECIP FROM SNOW OVER
TO SLEET AND FREEZING RAIN. WITH THAT SAID... GIVEN THE SURFACE HIGH
IS TRANSITORY WITH THIS SYSTEM (HINTS THE INSITU DAMMING) THE
FREEZING RAIN WILL BE A SELF LIMITING PROCESS... WHICH WILL HELP
KEEP TOTALS OF FREEZING RAIN BELOW WARNING CRITERIA AREA WIDE...
THOUGH LOCATIONS ACROSS THE NORTHWEST PIEDMONT COULD SEE A COUPLE OF
INCHES OF SNOW/SLEET... WITH UP TO A TENTH OF AN INCH OF ICE ACCRUAL
BEFORE TEMPS CLIMB TO 33 LATE IN THE DAY/MONDAY EVENING... WITH
LESSER AMOUNTS AS YOU GO SOUTH AND EASTWARD (THOUGH WE STILL MAY SEE
SOME TRAVEL ISSUES ON MONDAY MORNING INTO THE AFTERNOON).

THE BULK OF THE PRECIP THOUGH WILL OCCUR ON MONDAY NIGHT AS THE MAIN
S/W ENERGY AND DEEPENING SURFACE LOW TRACK ACROSS THE AREA. WE COULD
SEE UP TO 1 TO 2 INCHES OF RAIN WITH THIS SYSTEM... WITH EVEN A FEW
THUNDERSTORMS POSSIBLE ACROSS THE AREA IF THE MID LEVEL TROUGH TAKES
ON A NEGATIVE TILT. LOW TEMPS FOR THE PERIOD MONDAY NIGHT/TUESDAY
MORNING MAY OCCUR EARLY (ESPECIALLY IN THE WEAKENING DAMMING
REGION... NW PIEDMONT) WITH TEMPS HOLDING STEADY OR RISING
OVERNIGHT. HIGH TEMPS WILL BE TRICK AND DEPEND ON THE TIMING OF THE
ASSOCIATED SURFACE FRONT TRACKING THROUGH THE AREA AS THE SURFACE
LOW LIFTS OFF TO THE NORTH AND EAST... AND HOW MUCH PARTIAL CLEARING
WE MAY SEE ON TUESDAY AFTERNOON...ALONG WITH WESTERLY LOW LEVEL
FLOW. FOR NOW WILL SHOW HIGHS RANGING FROM NEAR 50 NW TO NEAR 60S
SE/E... WITH PRECIP EXITING THE AREA TUESDAY MORNING INTO THE
AFTERNOON.

TUESDAY NIGHT THROUGH FRIDAY: DRY WEATHER IS EXPECTED TO RETURN FOR
THIS PERIOD... THOUGH A QUICK MOVING MOISTURE STARVED DISTURBANCE IS
EXPECTED TO MOVE THROUGH THE AREA ON TUESDAY NIGHT/WEDNESDAY.
OTHERWISE... HIGH PRESSURE AT THE SURFACE AND ALOFT WILL BUILD OVER
THE REGION... RESULTING IN DRY AND QUITE WEATHER... WITH HIGH AND
LOW TEMPS RETURNING TO NEAR NORMAL VALUES.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 642 AM SATURDAY

HIGH CONFIDENCE THAT VFR WILL EXIST ACROSS CENTRAL SUNDAY THROUGH SUNDAY.

EXCEPT FOR A FEW-SCATTERED STRATOCU TODAY...SKIES WILL BE CLEAR. SFC
WINDS WILL BE BRISK WITH GUSTS 22-27KTS HIGHLY PROBABLE FROM THE NW.
THESE BRISK WINDS WILL SLOWLY SUBSIDE LATER TONIGHT.

VFR CONDITIONS TO CONTINUE INTO SUNDAY THOUGH MID-HIGH LEVEL CLOUDS
WILL BE INCREASING DURING THE DAY AS AN AREA OF LOW PRESSURE APPROACHES
FROM THE WEST. MOISTURE AHEAD OF THIS SYSTEM WILL LEAD TO SUB VFR
CEILINGS ALONG WITH PATCHES OF PRECIPITATION LATE SUNDAY NIGHT INTO
MONDAY. AT ONSET...THIS PRECIPITATION MAY OCCUR AS A WINTRY
MIX. THE SUB VFR CONDITIONS MAY LINGER INTO EARLY TUESDAY WITH
IMPROVING CONDITIONS LATE TUESDAY INTO WEDNESDAY.

&&

.CLIMATE...

HERE ARE THE RECORD LOWS AND RECORD LOW MAXIMUM TEMPERATURES FOR
FEB 13TH AND FEB 14TH AT GSO... RDU... AND FAY:


       REC    YR     REC    YR
       LOW         LOW MAX
----------------------------------------------
GSO:
02/13                 31   1986
02/14    6   1905     22   1914

RDU:
02/13                 10   1899
02/14   -2   1899     27   1916

FAY:
02/13                 32   1955
02/14   12   1968     33   1916

&&

.RAH WATCHES/WARNINGS/ADVISORIES...

NONE

&&

$$

SYNOPSIS...WSS
NEAR TERM...ELLIS
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...WSS
CLIMATE...RAH


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