Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 122022
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
320 PM EST FRI FEB 12 2016

.SYNOPSIS... A LOW PRESSURE CENTER WILL TRACK EAST OFF THE COAST
THIS EVENING. ARCTIC HIGH PRESSURE WILL BUILD OVER THE REGION OVER
THE WEEKEND. A DEVELOPING STORM SYSTEM WILL APPROACH FROM THE WEST
SUNDAY NIGHT AND THEN MOVE EASTWARD THROUGH THE AREA MONDAY THROUGH
TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 PM FRIDAY...

AS LOW PRESSURE CONTINUES TO DEVELOP OFF OF THE COAST...THE TRAILING
EDGE OF THE PRECIPITATION IS NOW EAST OF US 1 AND WILL QUICKLY MOVE
EASTWARD OVER THE NEXT FEW HOURS. LIGHT ACCUMULATIONS...MAINLY UNDER
A HALF OF AN INCH OF SNOW HAVE BEEN REPORTED UNDER THE HEAVIER
RETURNS WITH A MIX OF SLEET AND FREEZING RAIN ACROSS THE SOUTHERN
COUNTIES. THIS WILL BE THE STATUS QUO FOR THE NEXT COUPLE HOURS
BEFORE CLEARING OUT. WITH COLD TEMPERATURES IN PLACE ALREADY...NOT
MUCH CHANCE TO GET BACK ABOVE FREEZING TODAY EXCEPT IN THE EXTREME
WESTERN COUNTIES WHERE MID 30S WILL BE POSSIBLE. IMPACTS TO ROADS
HAVE BEEN MINIMAL AT THIS POINT AND ARE EXPECTED TO CONTINUE TO BE
MINIMAL OVERNIGHT. TIMING LOOKS GOOD ENOUGH THAT WINTER WEATHER
ADVISORY SHOULD BE ABLE TO BE LEG GO BY THE EXPIRATION TIME OF 00Z.
ANY EXTENSION OF THE ADVISORY WOULD BE FOR RESIDUAL
EFFECTS...PERHAPS IN SOUTHERN COUNTIES WHERE MORE FREEZING RAIN HAS
BEEN REPORTED.

AS THE SYSTEM MOVES OFF...SKIES WILL CLEAR FAIRLY QUICKLY AND THUS
TEMPERATURES TONIGHT WILL BEGIN TO DROP QUITE A BIT. LOW
TEMPERATURES IN THE LOW 20S ACROSS THE NORTH TO MIDDLE 20S IN THE
SOUTH.

&&

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

AS EAST COAST TROUGH TRIES TO PULL OFF THE COAST...VERY STRONG COLD
AIR ADVECTION WILL ENSUE BEHIND THE EXITING COASTAL SYSTEM. WITH
VERY STRONG PRESSURE GRADIENT ACROSS THE AREA...COLD TEMPERATURES
AND STRONG WINDS WILL BE THE FORECAST PROBLEM OF THE DAY. EXPECT
WINDS TO REMAIN SUSTAINED OUT OF THE NORTH OR NORTHWEST AT 10-15 KTS
WITH GUSTS OF 25-30 KTS FOR MUCH OF THE DAYLIGHT HOURS. AFTER SUNSET
GUSTS WILL SUBSIDE. HIGH TEMPERATURES ONLY IN THE LOW TO MID 30S AND
WITH WIND CHILL VALUES IN THE UPPER 10S TO LOW 20S FOR MUCH OF THE
DAY. AS AN ASIDE...WITH THE COLD BUT ALSO DRY AIRMASS IN PLACE...MIN
RH VALUES WILL DIP DOWN INTO THE LOW 20S. COMBINE THESE VALUES WITH
THE HIGHER WINDS AND THERE WILL BE A SMALL INCREASE IN FIRE DANGER
SATURDAY IN OUR SOUTHERN COUNTIES THAT MAY SQUEAK INTO THE LOWER
40S.

SATURDAY NIGHT WILL SEE THE GUSTS SLACK OFF BUT SUSTAINED WINDS TO
REMAIN UP IN THE 5 TO 10 KT RANGE KEEP THINGS MIXED A LITTLE.
COMBINE THIS WITH VERY COLD EXPECTED LOW TEMPERATURES IN THE LOW TO
MID TEENS...WIND CHILL VALUES SATURDAY NIGHT WILL RESIDE IN THE 5-10
DEGREE RANGE. PREPARATIONS SHOULD BE MADE NOW TO PROTECT ANYTHING
SUSCEPTIBLE TO THE COLD WIND CHILLS...ESPECIALLY PETS. SOME CLOUDS
WILL BEGIN TO APPROACH THE AREA LATE SATURDAY NIGHT INTO SUNDAY
MORNING FROM THE WEST IN ADVANCE OF THE NEXT STORM SYSTEM.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
AS OF 315 PM FRIDAY...

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

SUNDAY: CONTINUED CHILLY WITH THE ARCTIC HIGH PRESSURE EXTENDING
FROM THE ERN GREAT LAKES DOWN THROUGH NC. WILL HAVE INCREASING
CLOUDS AHEAD OF THE APPROACHING STORM... AS OUR MID LEVEL FLOW
SHIFTS FROM FAST NORTHWESTERLY TO WEST-SOUTHWEST... A FUNCTION OF
PACIFIC NORTHWEST ENERGY DIVING INTO AN INITIALLY FLAT/BROAD CENTRAL
CONUS TROUGH CAUSING ITS AMPLIFICATION. STATISTICAL GUIDANCE STILL
SUPPORTS HIGHS FROM 29 NE TO 35 SW. -GIH

SUN NIGHT THROUGH TUE:

OVERVIEW: CONFIDENCE IS BEGINNING TO INCREASE REGARDING THE
TIMING... MOST PROBABLE PRECIP TYPE PATTERN... AND PRIMARY WEATHER
THREATS FOR THE INCOMING SYSTEM. LATEST GUIDANCE SHOWS A BIT QUICKER
ONSET... WITH PRECIP ARRIVING IN THE NRN/WRN CWA SUN NIGHT... AS
WELL AS A SLIGHTLY EARLIER DEPARTURE ON TUE. LONGWAVE TROUGHING WILL
CONTINUE TO AMPLIFY ALONG THE MISS VALLEY AS NRN STREAM ENERGY DROPS
INTO ITS BASE OVER THE GULF STATES... CULMINATING IN A NARROW DEEP
SHORTWAVE TROUGH TAKING ON A POSITIVE TILT AS IT SWINGS ENE INTO THE
CAROLINAS. AT THE SURFACE... THE POLAR HIGH SITUATED OVER THE
NORTHEAST AND MIDATLANTIC STATES SUN NIGHT CONTINUES TO PUSH
STEADILY NORTHEAST AND OFFSHORE THROUGH MON... WHILE A COASTAL FRONT
FORMS ALONG THE CAROLINA COAST EXTENDING BACK TO DEVELOPING LOW
PRESSURE OVER THE CENTRAL GULF STATES. THIS LOW THEN TRACKS EAST
THEN NE THROUGH WRN NC MON NIGHT/TUE MORNING BEFORE MOVING QUICKLY
INTO THE NORTHEAST STATES... WITH A TRAILING FRONT SWEEPING THROUGH
CENTRAL/ERN NC BY EARLY TUE AFTERNOON.

PRECIPITATION CHANCES: THE INITIAL PROCESSES TO FORCE ASCENT SUNDAY
NIGHT INTO EARLY MONDAY INCLUDING DPVA AND MOIST ISENTROPIC UPGLIDE
ARE RATHER WEAK AND FOCUSED PRIMARILY ON WRN AND NRN PORTIONS OF
CENTRAL NC. WILL TREND POPS UP TO LIKELY NW AND RETAIN HIGH CHANCES
ACROSS THE SOUTH AND EAST SUN NIGHT INTO MON MORNING... WITH QPF
FAIRLY LIGHT... UNDER A QUARTER INCH MAINLY IN THE NW. BUT THIS
CHANGES QUICKLY WITH THE ADDITION OF STRONG UPPER DIVERGENCE (DUE TO
IDEALLY JUXTAPOSED POLAR AND SUBTROPICAL JETS) AND VIGOROUS LOW
LEVEL MOISTURE TRANSPORT EAST OF THE LOW. WILL RAMP UP POPS FURTHER
TO CATEGORICAL WEST/LIKELY EAST LATE MON... THEN TO CATEGORICAL
EVERYWHERE MON NIGHT THROUGH TUE MORNING... ENDING SW TO NE TUE
AFTERNOON.

PTYPES: USING THE TOP-DOWN METHODOLOGY WITH CONSIDERATION OF THE
INITIALLY VERY COLD/DENSE NATURE OF THE SURFACE AIR MASS... THE
INITIAL COLD AIR ALOFT GIVING WAY TO A WARM NOSE... AND THE STRONG
LOW LEVEL WARM ADVECTION APT TO DISLODGE THIS SURFACE AIR MASS
GRADUALLY FROM SE TO NW MON EVENING... EXPECT THIS TO START AS
MOSTLY LIGHT SNOW WITH PERHAPS PATCHY LIGHT SLEET SUN NIGHT ACROSS
THE NRN AND WRN CWA... FOLLOWED BY A SLOW STEADY TRANSITION FROM SSE
TO NNW TO FREEZING RAIN/SLEET THEN TO ALL RAIN... WITH THE FAR NW
COUNTIES INCLUDING THE TRIAD THE LAST TO SEE AN END TO THE WINTRY
PRECIP MON EVENING. TENTATIVE ACCUMULATIONS ARE UP TO ONE TO TWO
HUNDREDTHS OF AN INCH OF ICING (TRACE AMOUNTS) FOR MUCH OF THE
CWA... AND SNOW TOTALS OF 1-3" NW QUARTER WITH AN INCH OR LESS
ELSEWHERE... ALL OF WHICH SHOULD BE QUICKLY SWEPT AWAY BY MODERATE
TO POTENTIALLY HEAVY RAINFALL LATE MON NIGHT INTO TUE MORNING.

RAINFALL TOTALS AND STORM POTENTIAL: AT THIS TIME STORM TOTAL LIQUID
QPF IS EXPECTED TO BE 1-2" WITH LOCALLY HIGHER AMOUNTS POSSIBLE...
GIVEN THE HIGH WATER CONTENT AND STRONG LIFT MON NIGHT/TUE MORNING.
BASED ON THE ANTECEDENT CONDITIONS AND SEVERAL RIVERS AND CREEKS
RUNNING HIGH... A FLOOD WATCH MAY BE NEEDED FOR SOME PORTION OF THE
AREA. ALSO... WHILE LAPSE RATES ARE UNLIKELY TO BE VERY
IMPRESSIVE... THE STRONG AND FOCUSED LIFT POSSIBLE WITH THIS SYSTEM
AND WARMING LOW LEVELS ESPECIALLY IN THE SANDHILLS AND COASTAL PLAIN
MAY SUPPORT A FEW LIGHTNING STRIKES ON TUE.

TEMPS: EXPECT LOWS SUN NIGHT OF 22-26. TEMPS SHOULD SLOWLY RISE MON
THROUGH MON NIGHT... REACHING THE LOW 30S NW TO LOW 40S SE LATE
MON... RISING TO THE MID 30S NW TO MID 40S SE MON NIGHT... AND
PEAKING AT 48-56 TUE PRIOR TO FRONTAL PASSAGE.

WED THROUGH FRI: WE MAY SEE A PERTURBATION SWING THROUGH THE
LONGWAVE ERN TROUGH BASE ACROSS VA ON WED... BUT MODELS VARY ON THE
STRENGTH AND LATITUDE OF ANY SUCH WAVE... AND REGARDLESS THE
MOISTURE WILL BE LIMITED YIELDING NO IMPACTS ON CENTRAL NC OTHER
THAN SOME CLOUDS ACROSS THE NORTH. OTHERWISE... THIS PERIOD WILL
FEATURE A TRANSITION AWAY FROM WRN RIDGE/ERN TROUGH OVER THE
CONUS... AS FLAT RIDGING BUILDS OVER THE GULF/SOUTHEAST STATES FROM
THE WEST... WITH A NET RESULT OF DRY WEATHER AND NEAR TO SLIGHTLY
ABOVE NORMAL TEMPS FOR CENTRAL NC. -GIH

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 145 PM FRIDAY...

24 HOUR TAF PERIOD: SHORT FUSE WINTER WEATHER EVENT IN THE EASTERN
HALF OF THE AREA WILL WIND DOWN LATER THIS AFTERNOON WITH KFAY AND
KRWI THE AFFECTED SITES. A MIX OF WINTER P-TYPES AT KFAY WITH LIGHT
FREEZING RAIN THE MOST LIKELY SCENARIO FROM THIS POINT ON AND THAT
IS WHAT IS CURRENTLY BEING REPORTED AT KFAY. FURTHER TO THE NORTH
KRWI WILL EXPERIENCE MORE SNOW OR SNOW AND SLEET MIX OVER THE NEXT
FEW HOURS BEFORE THE SYSTEM BEGINS TO PULL OFF TO THE EAST. ONCE
PRECIPITATION ENDS...CONDITIONS SHOULD RETURN TO VFR AND ARE
EXPECTED TO REMAIN THERE THROUGH THE REMAINDER OF THE TAF PERIOD.

THE MAIN STORY FOR SATURDAY WILL BE GUSTY WINDS WITH SUSTAINED
VALUES OF 15 KTS OUT OF THE NORTHWEST...GUSTING TO 25-30 KTS AT ALL
TAF SITES. GUSTS WILL CONTINUE THROUGH THE AFTERNOON ON SATURDAY.


LONG TERM: THE NEXT POTENTIAL FOR ADVERSE CONDITIONS WILL COME ON
MONDAY NIGHT THROUGH TUESDAY AS A LOW PRESSURE SYSTEM MOVES THROUGH
THE AREA.

&&

.CLIMATE...

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


       REC    YR     REC    YR
       LOW         LOW MAX
----------------------------------------------
GSO:
02/13   11   1955     31   1986
02/14    6   1905     22   1914

RDU:
02/13    4   1899     10   1899
02/14   -2   1899     27   1916

FAY:
02/13   14   1973     32   1955
02/14   12   1968     33   1916

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY THROUGH 7 PM EST TODAY FOR
NCZ010-011-026>028-041>043-077-078-085-086-088-089.

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...ELLIS
SHORT TERM...ELLIS
LONG TERM...HARTFIELD
AVIATION...ELLIS
CLIMATE...RAH


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