Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 260711
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
210 AM EST MON JAN 26 2015

.SYNOPSIS... A STRONG UPPER LEVEL DISTURBANCE WILL CROSS THE REGION
TODAY INTO EARLY TONIGHT. CHILLY HIGH PRESSURE WILL BUILD IN FROM
THE NORTHWEST TUESDAY THROUGH WEDNESDAY NIGHT. A CLIPPER LOW
PRESSURE SYSTEM WILL MOVE THROUGH THE AREA THURSDAY INTO EARLY
FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 918 PM SUNDAY...

AMPLIFYING SHORTWAVE TROUGH OVER THE TN VALLEY WILL DIG SEWD INTO
THE SOUTHEAST US THROUGH DAYBREAK. ATTENDANT SFC LOW PRESSURE AREA
WILL SLIDE EASTWARD ACROSS THE CAROLINAS MONDAY MORNING AND WILL
TRACK NEWD UP THE MID-ATLANTIC COAST ON MONDAY EVENING-NIGHT.

WHILE MOISTURE IS LIMITED(PWS 0.50-0.60")...INTENSE H5 FALLS ON THE
ORDER OF 120-140 METERS AND STEEP MID-LEVEL LAPSE RATES ACCOMPANYING
THE UPPER TROUGH WILL HELP TO SUPPORT A BAND OF SCATTERED RAIN
SHOWERS INTO THE AREA AFTER MIDNIGHT WITH WARM BOUNDARY LAYER TEMPS
PRECLUDING ANY P-TYPE CONCERNS. TEMPS MAY FALL ANOTHER DEGREE OR
TWO..WITH TEMPS LEVELING OUT WIT THE ARRIVAL OF THE THICKER CLOUD
COVER. LOWS RANGING FROM MIDS IN THE EAST TO UPPER 30S/NEAR 40 WEST.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
AS OF 310 PM SUNDAY...

AS THE VORTICITY ALOFT TRACKS NEAR THE NC/VA BORDER MONDAY... ENERGY
WILL BE FOCUSED OFFSHORE AS THE SURFACE LOW PRESSURE IS FORECAST TO
TAKE SHAPE OFF CAPE HATTERAS... THEN PULL NORTHWARD UP THE EASTERN
SEABOARD MONDAY NIGHT AND TUESDAY. MOST IF NOT ALL THE SIGNIFICANT
RAIN WILL FALL OFFSHORE WITH THE STORM ITSELF AT OUR LATITUDE.
HOWEVER... SOME WRAP AROUND MOISTURE FROM THE STORM WILL AFFECT THE
NORTHERN AND EASTERN ZONES MONDAY AFTERNOON THROUGH MONDAY NIGHT AS
THE MID/UPPER LEVEL ENERGY SHIFTS OVER NE OVER THE WASHINGTON-
PHILADELPHIA REGIONS. WE WILL CONTINUE WITH A CHANCE OF SHOWERS
(RAIN) MONDAY AS TEMPERATURE PROFILES INDICATE THE BOUNDARY LAYER
WILL BE TOO WARM TO SUPPORT ANY SNOW. HOWEVER... THERE MAY BE A
BRIEF WINDOW OF OPPORTUNITY FOR A CHANGE TO LIGHT SNOW OR SNOW MIXED
WITH RAIN SHOWERS IN THE NE ZONES AS THE COLDER AIR SURGES INTO THE
REGION BEHIND THE DEPARTING SYSTEM MONDAY NIGHT. AGAIN... COLD AND
DRY AIR CHASING THE MOISTURE IS NOT A CONCERN FOR ANY SNOW
ACCUMULATIONS. EVEN IF THERE ARE A FEW SNOW FLAKES OR FLURRIES AT
THE END OF THE EVENT (MAINLY RDU NORTH AND EAST) - IT IS NOT
EXPECTED TO STICK.

SENSIBLE WEATHER FOR MONDAY AND MONDAY NIGHT... CLOUDY BECOMING
PARTLY CLOUDY IN THE SOUTHWESTERN PIEDMONT IN THE AFTERNOON. A
CHANCE OF LIGHT RAIN SHOWERS. QPF WILL BE ONLY A FEW HUNDREDTHS UP
TO A TENTH NORTHEAST. HIGHS GENERALLY 40S NORTH TO 50S SOUTH. A
CHANCE OF A FEW LINGERING SHOWERS MONDAY NIGHT IN THE NORTH AND
EAST... MAY BECOME A FEW LIGHT FLURRIES BEFORE THE DRY AIR WINS OUT.
BECOMING CLEAR SOUTH AND WEST. BREEZY. LOWS 25-30 WEST AND 33-35 NE.

TUE AND TUE NIGHT: EXPECT BELOW NORMAL TEMPERATURES DURING THE DAY
TUE IN ASSOC/W LOW-LEVEL COLD ADVECTION ON THE SOUTHWEST PERIPHERY
OF A POTENT NOR`EASTER TRACKING NORTHEAST ALONG THE NEW ENGLAND
COAST...AND SCATTERED TO BROKEN LOW/MID-LEVEL CEILINGS...ESP IN N/NE
PORTIONS OF CENTRAL NC...AS SHORTWAVE ENERGY /DPVA/ PROGRESSES
SOUTHWARD ALONG THE WESTERN PERIPHERY OF THE MATURING UPPER LEVEL
WAVE ALONG THE MID-ATLANTIC COAST. EXPECT DRY CONDITIONS ASIDE FROM
A SMALL CHANCE FOR SPRINKLES IN THE NE COASTAL PLAIN DURING THE
EARLY MORNING HOURS. SKIES WILL CLEAR TUE NIGHT IN ASSOC/W SYNOPTIC
SUBSIDENCE AS THE MATURE /VERTICALLY STACKED/ UPPER LOW PROGRESSES
FURTHER NORTHEAST ALONG THE NEW ENGLAND COAST. A RELATIVELY TIGHT
MSLP GRADIENT AND PERSISTENT NW BREEZE WILL PREVENT FULL RADIATIONAL
COOLING...WITH LOWS WED MORNING IN THE MID 20S...COLDEST ALONG THE
YADKIN RIVER WHERE WINDS WILL WEAKEN THE MOST PRIOR TO SUNRISE.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 210 AM MONDAY...

WED/WED NIGHT: QUIET WEATHER WITH MID LEVEL SHORTWAVE RIDGING
SHIFTING OVERHEAD AS HIGH PRESSURE RIDGING MOVES OVERHEAD. COLUMN IS
STABLE AND FAIRLY DRY WED... SO EXPECT PLENTY OF SUNSHINE. BELOW-
NORMAL THICKNESSES (BY 25-30 M) AND STATISTICAL GUIDANCE SUPPORT
COOL HIGHS OF 42-47. HIGH CLOUDS WILL INCREASE AND THICKEN WED
NIGHT... WITH A FLATTENING AND ACCELERATING WRLY FLOW ALOFT AND
INITIALLY WEAK MID LEVEL DPVA AHEAD OF A CLIPPER SHORTWAVE TROUGH
DIVING THROUGH THE UPPER MIDWEST. THESE HIGH CLOUDS MAY TAKE THE
EDGE OFF AN OTHERWISE GOOD NIGHT FOR RADIATIONAL COOLING... WITH
GENERALLY LIGHT WINDS AND LOW DEWPOINTS... BUT STILL EXPECT CHILLY
LOWS MOSTLY IN THE MID 20S.

THU/THU NIGHT: THIS WILL BE OUR NEXT CHANCE AT PRECIP... ALTHOUGH
SPECIFIC TIMING AND AMOUNTS ARE IN QUESTION AS GFS/ECMWF SOLUTIONS
DIVERGE. THE GREAT LAKES SHORTWAVE TROUGH WILL TRACK ESE THEN
EASTWARD ACROSS THE NORTHEAST/MIDATLANTIC STATES -- TRACKING THROUGH
THE BASE OF THE POLAR LOW OVER HUDSON BAY -- WHILE ITS CORRESPONDING
SURFACE LOW CROSSES THE OH VALLEY AND MIDATLANTIC COAST. GFS BUFR
SOUNDINGS SHOW CLOUD BASES STEADILY LOWERING THU MORNING AS LOW
LEVEL FLOW STRENGTHENS FROM THE WSW... PUSHING PW VALUES UP...
ALTHOUGH THEY PEAK AT JUST SLIGHTLY ABOVE-NORMAL VALUES... WITH A
LINGERING DRY SUBCLOUD LAYER OVER MUCH OF THE CWA. MOISTURE IS
DEEPEST AND MOST PRONOUNCED IN THE EASTERN PART OF THE FORECAST AREA
IN BOTH THE GFS AND ECMWF... HOWEVER THE ECMWF AND ITS DEEPER WAVE
GENERATES MORE QPF MUCH LATER (THU EVENING/NIGHT) COMPARED TO THE
LIGHTER/EARLIER GFS (BEST PRECIP CHANCES THU MORNING). WILL LEAN
TOWARD THE ECMWF... WHICH HAS DONE BETTER SHOWING DEEPER WAVES IN
RECENT WEEKS... BUT WILL KEEP POPS NO GREATER THAN 20-30% LATE THU
THROUGH THU NIGHT... FOCUSED ON THE EASTERN CWA. OVERALL MOISTURE
INFLUX DOES NOT APPEAR SUFFICIENT ENOUGH TO WARRANT ANYTHING MORE
THAN LIGHT QPF. SURFACE WET BULBS SHOULD BE INCHING ABOVE THE
FREEZING MARK BY THE TIME PRECIP BEGINS... AND THE LATER ARRIVAL
TIME SHOULD ENSURE THAT TEMPS THU NIGHT STAY MOSTLY ABOVE FREEZING.
EVEN SO... WE`RE LIKELY TO SEE DRYING ALOFT THU NIGHT AFTER THE MID
LEVEL TROUGH AXIS SWINGS THROUGH... WHICH WOULD LIMIT THE NON-LIQUID
PRECIP THREAT ANYWAY. TOTAL QPF SHOULD BE LIGHT... UNDER A QUARTER
INCH. HIGHS THU 47-52. LOWS THU NIGHT IN THE MID-UPPER 30S.

FRI-SUN: THE POLAR FRONT DROPS TO OUR SOUTH FRI... AND LOW LEVEL
THICKNESSES SLIP BACK TO AROUND 20 M BELOW NORMAL... YIELDING BELOW-
NORMAL HIGHS IN THE MID 40S TO LOWER 50S DESPITE FAIR SKIES AS COOL
HIGH PRESSURE BUILDS IN FROM THE NORTHWEST. LOWS FRI NIGHT IN THE
MID-UPPER 20S. UNCERTAINTY INCREASES FOR SAT/SUN AS THE GFS/ECMWF
SOLUTIONS CONTINUE TO DIVERGE IN IMPORTANT WAYS. BOTH HAVE A POLAR
LOW OVER HUDSON BAY/JAMES BAY AND ANOTHER LOW OVER NRN BAJA EARLY
SAT. THE GFS REMAINS FOCUSED ON THE POLAR STREAM... TAKING YET
ANOTHER CLIPPER WAVE THROUGH THE DAKOTAS AND MIDWEST THROUGH THE
NORTHEAST AND MIDATLANTIC THROUGH SUN... BRINGING ENHANCED
CLOUDINESS AND PERHAPS LIGHT PRECIP TO CENTRAL NC SAT (LIMITED BY
THE WEAK MOISTURE RETURN). THE ECMWF ON THE OTHER HAND IS MORE
FOCUSED ON THE SOUTHERN STREAM... EASING THE BAJA LOW SLIGHTLY
EASTWARD INTO NW MEXICO WITH SURFACE LOW PRESSURE FORMING IN THE NW
GULF... WHILE SRN STREAM ENERGY BEGINS TO SHEARS ENE TOWARD NC. THE
LATTER SOLUTION IS WARMER AND DRIER BUT STARTS TO BRING IN MOIST
OVERRUNNING FLOW BY LATE SUN. GIVEN THIS DISPARITY... PREFER JUST A
SMALL CHANCE POP ON SUN FOR NOW... WITH TEMPS REMAINING BELOW
NORMAL. -GIH

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 105 AM MONDAY...

24 HOUR TAF PERIOD: VFR CONDITIONS CONTINUING TO PREVAIL THIS
MORNING AS HIGH CLOUDS ARE NOW OVERSPREADING THE AREA FROM THE WEST
IN ASSOCIATION WITH THE APPROACHING CLIPPER SYSTEM. BETWEEN NOW AND
12Z MODELS AGREE ON SOME LOWERING OF CEILINGS BUT UPSTREAM
OBSERVATIONS HAVE YET TO SHOW MUCH OF A HINT OF THIS. THIS IS A LOW
CONFIDENCE FORECAST AT THIS TIME AND WILL COVER IN THE TAFS WITH
SOME MVFR VISIBILITIES AND CEILINGS IN THE NORTHWEST LATER THIS
MORNING BUT WILL HOLD OFF IN THE EAST ON ANY DETERIORATION IN
CONDITIONS AT KRDU AND KRWI UNTIL LATER IN THE AFTERNOON. KFAY MAY
REMAIN VFR THROUGH THE TAF PERIOD AS MOST OF THE LIGHT RAIN
ASSOCIATED WITH THIS SYSTEM IS EXPECTED TO REMAIN ACROSS THE NORTH.
FORECAST SOUNDINGS SHOW SOME ELEVATED INSTABILITY LATER IN THE
AFTERNOON AND AN ISOLATED THUNDERSTORM CANNOT BE RULED OUT BUT THIS
WILL BE THE EXCEPTION TO THE RULE. AS THE WAVE PASSES THROUGH WINDS
WILL SHIFT TO NORTHWESTERLY AND BEGIN GUSTING UP TO 20-25
KTS...PRIMARILY AFTER 00Z TUESDAY. GUSTS WILL CONTINUE THROUGH THE
END OF THE TAF PERIOD.

LONG TERM: ONCE VFR CONDITIONS RETURN ON THE HEELS OF THIS
SYSTEM...THEY SHOULD REMAIN VFR UNTIL THE NEXT SYSTEM APPROACHES
FORM THE NORTHWEST ON THURSDAY NIGHT INTO FRIDAY.

&&

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

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...CBL
SHORT TERM...BADGETT/BV
LONG TERM...HARTFIELD
AVIATION...ELLIS



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