Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 102033
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
335 PM EST WED FEB 10 2016

.SYNOPSIS...A DEEP UPPER LEVEL TROUGH WILL PERSIST OVER THE EASTERN
UNITED STATES TODAY THROUGH THURSDAY. AN UPPER LEVEL DISTURBANCE
WILL CROSS THE SOUTHEAST STATES LATE THURSDAY THROUGH FRIDAY. ARCTIC
HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST LATE FRIDAY THROUGH
THE WEEKEND. A STORM SYSTEM WILL AFFECT THE REGION NEXT MONDAY.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
AS OF 330 PM WEDNESDAY...

THROUGH TONIGHT: THE AXIS OF A 500 MB TROUGH CONTINUES TO PASS
THROUGH THE AREA THIS AFTERNOON WITH A FAIRLY STRONG PRESSURE
GRADIENT FEATURING WEST NORTHWESTERLY SURFACE FLOW ACROSS THE CWA.
BECAUSE OF THIS GRADIENT COMBINED WITH A FAIRLY DEEP MIXED
LAYER...THE MAIN WEATHER STORY THIS AFTERNOON HAS BEEN SOME BREEZY
WINDS WITH MOST LOCATIONS OUT OF THE WEST NORTHWEST AT 10 KTS
GUSTING TO 20 KTS. THESE GUSTS SHOULD BEGIN TO SUBSIDE AFTER SUNSET
BUT SUSTAINED WINDS WILL REMAIN 5-10 KTS OVERNIGHT TONIGHT.

CLOUDS THAT HAVE DEVELOPED THIS AFTERNOON IN ASSOCIATION WITH THE
PASSING SHORTWAVE WILL MOVE OFF TO THE EAST LATER...PROMOTING SOME
CLEARING FROM THE WEST OVERNIGHT BUT INTERMITTENT CLOUDS WILL
REMAIN. THIS ALONG WITH SOME WINDS OVERNIGHT WILL KEEP IDEAL
RADIATIONAL COOLING CONDITIONS FROM FORMING BUT NONETHELESS WITH A
VERY COLD AIRMASS IN PLACE...UPPER TEENS TO LOW 20S SHOULD BE EASILY
ATTAINABLE OVERNIGHT TONIGHT AND INTO THURSDAY MORNING.

THURSDAY AND THURSDAY NIGHT: THE UPPER TROUGH WILL BEGIN TO RELAX AS
THE SURFACE LOW PRESSURE SYSTEM OFF OF NEW ENGLAND CONTINUES OUT TO
SEA. THICKNESSES WILL TAKE A WHILE TO RECOVER HOWEVER AND THE WARMER
THICKNESSES WILL REMAIN TO OUR SOUTH. THEREFORE NOT MUCH CHANGE IN
HIGH TEMPERATURE FOR THURSDAY WITH UPPER 30S TO LOWER 40S ACROSS THE
AREA. SKIES WILL BE MOSTLY CLEAR WITH PLENTY OF SUN HOWEVER WITH BUT
STILL A LITTLE BREEZY WITH GUSTS UP TO 15 KTS OR SO. THURSDAY NIGHT
WILL FEATURE A GRADIENT IN THE LOW TEMPERATURE FROM NORTH TO SOUTH
WITH UPPER TEENS NORTH TO MIDDLE 20S SOUTH AS A LOW PRESSURE SYSTEM
BEGINS TO DEVELOP SOUTH OF THE AREA LATE THURSDAY NIGHT INTO FRIDAY
MORNING.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 PM WEDNESDAY...

WITH THE LONGWAVE TROUGH HOLDING OVER ERN NOAM... A PERTURBATION NOW
COMING INTO THE PACIFIC NORTHWEST WILL RIDE ATOP THE WESTERN RIDGE
AND SHEAR OUT AS IT DIVES INTO THE TROUGH BASE AND EVENTUALLY
CROSSES THE CAROLINAS FRI GENERATING WEAK DPVA. THE FORCING FOR
ASCENT WITH THIS FEATURE WILL BE AUGMENTED BY UPPER DIVERGENCE IN
THE LEFT EXIT REGION OF THE JET DIVING INTO THE CENTRAL CONUS TOWARD
THE SOUTHEAST STATES... AND THIS WILL SUPPORT SURFACE LOW PRESSURE
DEVELOPMENT... TRACKING ACROSS AR AND THE GULF STATES/SRN GA/SRN SC
THU/THU NIGHT BEFORE SHIFTING OFF THE SC COAST FRI MORNING. THE
OVERALL LIFT IS NOT TERRIBLY IMPRESSIVE HOWEVER... AND THE LATEST
MODEL RUNS DO NOT SUBSTANTIALLY DEEPEN THE SURFACE LOW UNTIL IT IS
ALREADY WELL OFF THE COAST AND MOVING ENE AWAY FROM NC... KEEPING IT
RATHER WEAK AND FLAT WITHOUT A STRONG THERMAL ADVECTION PATTERN.
MOISTURE IS ALSO UNIMPRESSIVE... WITH FORECAST SOUNDINGS INDICATING
MULTIPLE UNSATURATED LAYERS AND INCONSISTENT MOISTENING ABOVE -10C
THAT BRINGS DOUBT AS TO THE PRESENCE OF ICE ALOFT. WITH MODELS
CONTINUING TO DEPICT VERY LIGHT TO NO QPF EXCEPT AS ONE GETS CLOSER
TO THE CENTRAL COASTAL AREA... WILL TAKE POPS AND AMOUNTS DOWNWARD
OVER MUCH OF THE CWA. THICKNESSES AND THE VERTICAL THERMAL
STRUCTURES NOTED ON FORECAST SOUNDINGS SUPPORT A MOSTLY RAIN/SNOW
MIX OVER THE FAR SE CWA... AND WHILE THIS IS THE AREA THAT IS MOST
LIKELY TO SEE SOME SLIGHTLY HEAVIER BANDED PRECIP ON THE NW SIDE OF
THE DEPARTING LOW... THE HIGH PROBABILITY OF A MIXTURE WILL KEEP ANY
ACCUMULATIONS VERY LOW... WITH ONLY A SLUSHY COATING AT MOST.
FURTHER INLAND... WITHIN THE COLDER THICKNESSES... ANY PRECIP SHOULD
BE LIGHT FLURRIES... YIELDING LITTLE MORE THAN A LIGHT DUSTING WITH
NO TRAVEL IMPACTS. EXPECT CONSIDERABLE CLOUD COVER FRI... WITH
CLEARING FRI NIGHT AS THE POLAR FRONT DROPS SOUTHEAST THROUGH THE
AREA... MOST LIKELY OCCURRING AFTER MIDNIGHT. HIGHS 36-42 FRI AND
LOWS 21-28. -GIH

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 330 PM WEDNESDAY...

...BITTERLY COLD AIR THIS WEEKEND WITH A WINTRY WEATHER THREAT EARLY
NEXT WEEK...

SAT/SUN: THE AFOREMENTIONED ARCTIC FRONT DROPPING SE THROUGH THE CWA
DURING THE PREDAWN HOURS SAT WILL INTRODUCE STRONG COLD AIR
ADVECTION AND A PLUNGE IN THICKNESSES (TO AROUND 80 M BELOW NORMAL)
AS A DENSE POLAR SURFACE HIGH STARTS TO BUILD IN FROM THE NW. THE
CORE OF THE HIGH WILL MOVE FROM THE MIDWEST FRI NIGHT ACROSS THE SRN
GREAT LAKES AND OH VALLEY TO THE MIDATLANTIC BY SUN EVENING WHILE
EXTENDING DOWN THROUGH NC. EXPECT DECENT SUNSHINE WITH LITTLE MORE
THAN FLAT CU SAT AFTERNOON WITH MIXING AND RESIDUAL MOISTURE BENEATH
THE SUBSIDENCE INVERSION ALOFT... AND INCREASING HIGH CLOUDS SUNDAY
AHEAD OF THE NEXT STORM SYSTEM. THE THICKNESSES PROJECTED BY THE
MODELS SUGGEST HIGHS BELOW FREEZING SAT ALONG/NORTH OF HIGHWAY 64...
AND BELOW FREEZING AREAWIDE ON SUNDAY... WITH LOWS AROUND 8 TO 15
SAT NIGHT. THE THICKNESS CLIMATOLOGY INDICATES THAT SINGLE DIGIT
LOWS ARE POSSIBLE SAT NIGHT... BUT WITH EXPECTATIONS OF SOME MIXING
PERSISTING OVERNIGHT... HAVE OPTED ON THE "WARM" SIDE OF THIS
CLIMATOLOGY. SEE CLIMATE SECTION BELOW. LOWS SUN NIGHT IN THE UPPER
TEENS TO LOWER 20S AS THE SURFACE HIGH DRIFTS NE TOWARD NEW ENGLAND.

MON THROUGH WED: MODEL DIFFERENCES WIDEN HEADING INTO MON AS ANOTHER
ROUND OF ENERGY SHIFTS INTO THE PLAINS BEFORE AMPLIFYING OVER THE
ERN STATES BY MID WEEK. IN SHORT... THE ECMWF SOLUTION (AND THE
CANADIAN IS SIMILAR) WAS PREFERRED OVER THE GFS... WITH THE FORMER
APPEARING MORE REASONABLE AND FITTING BETTER WITH CLIMATOLOGY.
ACCORDING TO THIS SOLUTION... A POTENT PERTURBATION WILL SWING
THROUGH OK MON THEN DEEPEN OVER THE LOWER MISS VALLEY MON NIGHT
BEFORE CROSSING THE TN VALLEY/SE/CAROLINAS/MIDATLANTIC TUE INTO WED.
THE ECMWF BRINGS STRONG MOISTURE ADVECTION AND DEEP LIFT STARTING
MON AND CONTINUING THROUGH TUE NIGHT... FINALLY SHIFTING TO OUR NE
WED... ALL THE WHILE TAKING A MILLER-B TYPE CYCLOGENESIS PATTERN
THROUGH THE REGION. THERE REMAINS A GREAT DEAL OF UNCERTAINTY
REGARDING THE VERTICAL THERMAL STRUCTURE AS WELL AS QPF... BUT
CONFIDENCE IN AT LEAST SOME PRECIP MON THROUGH TUE NIGHT IS HIGH
ENOUGH TO BUMP UP POPS INTO THE LIKELY CATEGORY. AND IF THE ECMWF IS
CORRECT... WE`D BE LOOKING AT A VERY WET EVENT... WITH A CHANCE OF
MOSTLY SNOW MON TRENDING UP TO MOSTLY RAIN MON NIGHT AS POPS
INCREASE... INDICATING A LOWER OVERALL IMPACT FROM WINTRY WEATHER.
BUT A LOT CAN CHANGE OVER THE NEXT SEVERAL MODEL RUNS... SO EVERYONE
SHOULD KEEP A CLOSE EYE ON THE LATEST FORECASTS. TEMPS SHOULD START
TO WARM UP INTO THE 30S MON... INTO THE 40S TUE AS WE GET INTO THE
WARM SECTOR... AND PERHAPS LOW 50S (CLOSE TO NORMAL) WED AS THE MID
LEVEL LOW MOVES NE AWAY FROM OUR AREA. -GIH

&&

.AVIATION /12Z THROUGH MONDAY/...
AS OF 105 PM WEDNESDAY...

24 HOUR TAF PERIOD: HIGH CONFIDENCE OF VFR CONDITIONS THROUGH THE
TAF PERIOD. WIND GUSTS WILL BE THE ISSUE OF THE DAY AS WEST
NORTHWESTERLY WINDS AT 10 KTS GUSTING 15-20 KTS WILL BE POSSIBLE AT
ALL TAF SITES TODAY. WINDS WILL REGRESS AFTER SUNSET BUT WILL SHOW
UP AGAIN AFTER 15Z THURSDAY. WITH DRY AIR IN PLACE...FOG OR LOW
STRATUS SHOULD NOT BE A PROBLEM OVERNIGHT. MAY SEE SOME MIDDLE TO
HIGH CEILINGS LATER IN THE DAY BUT NOTHING TO POSE A THREAT TO
AVIATION CONDITIONS.

LONG TERM: A COASTAL SYSTEM ON FRIDAY WITH A SHORTWAVE MOVING ACROSS
THE NORTH WILL BRING A CHANCE FOR SUB-VFR CONDITIONS PARTICULARLY AT
EASTERN TAF SITES. THE NEXT MORE SIGNIFICANT SYSTEM IS PROGGED TO
ENTER THE REGION MONDAY NIGHT INTO TUESDAY.

&&

.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...
NONE.


&&

$$

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


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