Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 041037
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
537 AM EST WED MAR 4 2015

.SYNOPSIS...
HIGH PRESSURE AND ASSOCIATED COLD AIR DAMMING WILL REMAIN UNTIL A
WARM FRONT RETREATS NORTH ACROSS CENTRAL NC LATER THIS MORNING
INTO THE AFTERNOON. MEANWHILE...A STRONG COLD FRONT WILL APPROACH
FROM THE NORTHWEST EARLY TONIGHT...THEN MOVE THROUGH THE AREA
LATER TONIGHT AND EARLY THURSDAY. COLD ARCTIC HIGH PRESSURE WILL
BUILD OVER THE REGION BEHIND THE FRONT FOR FRIDAY AND SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 435 AM WEDNESDAY...

...DENSE FOG ADVISORY THROUGH NOON TODAY...

THE BIG HEADACHE FOR THIS MORNING IS THE TIMING OF THE BREAKOUT OF
THE COLD AIR DAMMING OVER THE REGION. OBVIOUSLY...THE CAD WILL
ERODE WITH THE MEAN FLOW AN INCREASING SOUTHWESTERLY FLOW AND THE
FACT THAT ALL MODELS PLACE CENTRAL NORTH CAROLINA IN THE WARM
SECTOR THIS AFTERNOON. ALSO...THE TEMPERATURES AND DEW POINTS
WERE CURRENTLY IN THE 60S ACROSS MIDDLE TENNESSEE INTO
SOUTHEASTERN KENTUCKY AHEAD OF THE APPROACHING ARCTIC FRONT THAT
IS FORECAST TO STALL OVER THE MOUNTAINS LATER TODAY AND TONIGHT.
SEVERAL WAVES OF LOW PRESSURE ARE EXPECTED TO TRAVEL ALONG THE
FRONT LATE TONIGHT AND THURSDAY BRINGING HEAVY RAIN TO THE
TENNESSEE VALLEY NE ACROSS WEST VIRGINIA (WELL TO OUR NW). BACK TO
THE CAD EROSION...THIS CAD EVENT SHOULD ERODE FROM THE SW AND
FROM THE TOP DOWN DUE TO STRONG MIXING THIS MORNING. IT MAY BE
VERY LATE MORNING OR EARLY AFTERNOON BEFORE THE CAD IS COMPLETELY
GONE IN THE FAR NW PIEDMONT WHICH WILL BE THE LAST PLACE TO SEE
THE CAD`S DEMISE. BY AFTERNOON...ALL AREAS SHOULD BE SOLIDLY IN
THE WARM SECTOR WITH DEW POINTS EXPECTED TO JUMP INTO THE MID 50S
TO AROUND 60...TEMPERATURES INTO THE 70S...ALONG WITH A GUSTY SW
WIND AT 15-25 MPH WITH GUSTS TO 30 MPH. THE PARTLY SUNNY SKIES
WILL ADD TO THE FEEL OF SPRING THIS AFTERNOON.

TONIGHT...MODELS ARE AGAIN IN GENERAL AGREEMENT IN THE TIMING OF
FRONT LATER TONIGHT AND EARLY THURSDAY. THIS OCCURS AS AN INITIAL
WAVE OF LOW PRESSURE TRACKS FROM WESTERN NC INTO VA BETWEEN 06Z-
12Z...WHICH WILL PULL THE FRONT SOUTH THROUGH NC AFTER THE WAVE
PASSES. THE COLDEST ADVECTION SHOULD LAG THE FROPA BY 3-6 HOURS
WHICH WILL BE CRITICAL TO THE PRECIPITATION FORECAST FOR THURSDAY.
EXPECT RAIN TO DEVELOP OVER MUCH OF WESTERN AND NORTHERN SECTIONS
OF CENTRAL NC BEHIND THE FRONT LATE TONIGHT. INCREASING CLOUDINESS
IN THE SOUTHEAST AHEAD OF THE FRONT. LOWS WILL ONLY BE IN THE 50S
AND 60S NORTH TO SOUTH...WITH THE MAIN TEMPERATURE FALL EXPECTED
AFTER 12Z. INCREASING RAIN AND A NE FLOW WILL SPREAD IN BEHIND THE
FRONT MAKING THE MORNING WAIT AT THE BUS STOP RATHER MISERABLE IN
THE TRIAD AND TRIANGLE...LESS SO IN FAYETTEVILLE AND LAURINBURG...
ONLY TO ARRIVE TOWARD MID TO LATE MORNING.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
AS OF 255 AM WEDNESDAY...

THE CURRENT MODEL PROJECTIONS ARE ESSENTIALLY NEARLY IDENTICAL TO
THE PREVIOUS RUN AND FORECAST PACKAGE FOR THE PREDOMINATE P-TYPE,
QPF, AND TEMPERATURES FOR THURSDAY INTO THURSDAY NIGHT. THE
SPRAWLING ARCTIC PARENT HIGH PRESSURE CENTER WILL START THE DAY FAR
REMOVED FROM CENTRAL NC... OVER IOWA (1040 MB). THE COLDEST AIR WILL
INITIALLY BE BLOCKED BY THE APPALACHIAN PEAKS OF VA/NC... BUT THE
COLD AIR WILL SURGE SOUTH THROUGH MD AND VA INTO NC DURING THE LATE
MORNING AND AFTERNOON... THEN INTO THE SOUTHERN NC COUNTIES LATE
THURSDAY AFTERNOON. RAIN IS EXPECTED TO BE WIDESPREAD IN THE
ANAFRONT FASHION WITH A SW JET ALOFT RIDING UP AND OVER THE
INCREASINGLY COLD NE FLOW NEAR THE SURFACE. THE FINAL WAVE ALONG THE
FRONT WILL ENHANCE LIFT AND CONVERGENCE ACROSS THE REGION AS IT
TRACKS FROM THE SOUTHERN APPALACHIANS TO OFFSHORE OF SC/SOUTHERN NC
BY 00Z/FRI.

PARTIAL THICKNESSES SUGGEST THAT A GRADUAL MIX WITH OR CHANGEOVER TO
FREEZING RAIN SHOULD OCCUR ALONG THE NC/VA BORDER BY MID AFTERNOON
AS THE SURFACE TEMPERATURES AND DEW POINTS PLUNGE TO 32. WE WILL TRY
TO PLACE THE CHANGE OVER TIMING WITH THE LATEST FORECAST WET BULB
TEMPERATURE FORECASTS OFF A BLEND OF THE SREF AND OPERATIONAL
MODELS. THIS GRADUAL CHANGEOVER TO FREEZING RAIN... POSSIBLY MIXED
WITH A LITTLE SLEET WILL SLOWLY PUSH SOUTH AND WEST TOWARD THE TRIAD
AND TRIANGLE AREAS AND THE ROCKY MOUNT AND WILSON AREAS... BETWEEN
400 AND 700 PM.

KEEP IN MIND THAT FOR THE FREEZING RAIN TO ACTUALLY BEGIN TO BECOME
A HAZARD WILL TAKE LONGER THAN IN RECENT COLD STORMS...DUE TO THE
WARM GROUND... TIMING OF THE CHANGEOVER (LATE AFTERNOON)...AND THE
INCREASING SOLAR INSOLATION. IN ADDITION... THE WARM NOSE ALOFT IS
FORECAST TO LINGER THROUGH ALL BUT THE LAST GASPS OF THIS SYSTEM`S
PRECIPITATION. THEREFORE...A WARM WET GROUND...LITTLE "FROZEN"
PRECIPITATION...AND TIME OF DAY SHOULD PREVENT ALL BUT POSSIBLY THE
NORTHERN TIER OR TWO OF COUNTIES FROM HAVING FREEZING RAIN TO
ACCRUE. EVEN THERE...IT SHOULD BE ONLY SEVERAL HOURS IN WHICH THE
ACCRUAL WOULD BE LIMITED TO ELEVATED SURFACES.

THE REAL WEATHER HAZARD AS FAR AS ICE MAY NOT OCCUR UNTIL THE
PRECIPITATION ENDS THURSDAY EVENING. THIS IS WHEN THE TEMPERATURES
WILL REALLY FALL WITH STRONG CAA FROM THE NORTH AND CLEARING SKIES
LEADING TO TEMPERATURES QUICKLY FALLING THROUGH THE 20S. A WINTER
WEATHER ADVISORY FOR ICE OR BLACK ICE MAY BE NEEDED ESPECIALLY ALONG
AND NORTH OF THE TRIAD AND TRIANGLE AREAS TO WILSON AND ROCKY MOUNT
FOR THURSDAY NIGHT.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 245 AM WEDNESDAY...

FRI/FRI NIGHT: COLD ADVECTION ATTENDANT ~1040 MB ARCTIC HIGH
PRESSURE BUILDING INTO THE CAROLINAS FROM THE N/NW DURING THE DAY
WILL RESULT IN WELL...WELL BELOW NORMAL TEMPERATURES (AS MUCH AS 25-
30 DEGREES) ON FRIDAY...WITH THE LATEST 00Z GFS/ECMWF SUGGESTING
HIGHS RANGING FROM THE UPPER 20S TO LOWER 30S IN THE NE COASTAL
PLAIN TO LOW/MID 30S WEST/SW PIEDMONT. GIVEN CLEAR SKIES AND EARLY
MARCH INSOLATION...WILL REDUCE HIGHS SEVERAL DEGREES FROM THE PRIOR
FORECAST...REMAINING SEVERAL DEGREES ABOVE WHAT GUIDANCE ALONE WOULD
SUGGEST. LOWS FRI NIGHT IN THE UPPER TEENS NORTHEAST TO LOW/MID 20S
SOUTHWEST.

SAT-SUN NIGHT: UNIDIRECTIONAL FLOW ALOFT /DRY CONDITIONS/ AND MOSTLY
CLEAR SKIES ARE EXPECTED TO PREVAIL ACROSS THE REGION THROUGH THE
WEEKEND...WITH NORTHERN STREAM SHORTWAVE ENERGY CONFINED TO THE
GREAT LAKES /NEW ENGLAND/ AND SOUTHERN STREAM SHORTWAVE ENERGY
CONFINED TO THE DESERT SW AND WESTERN GOMEX. EXPECT MODERATING
TEMPS...THOUGH STILL BELOW NORMAL...WITH HIGHS GENERALLY IN THE 50S
SAT/SUN AND LOWS RANGING FROM THE LOWER 30S SAT NIGHT TO MID/UPPER
30S SUN NIGHT WHEN MID/UPPER LEVEL CLOUD COVER IS PROGGED TO
INCREASE AS SOUTHERN STREAM SHORTWAVE ENERGY...ATTENDANT
WAA/FGEN...AND RESULTING PRECIPITATION PROGRESS EASTWARD ALONG THE
GULF COAST.

MON-TUE: GIVEN A SPLIT FLOW SYNOPTIC PATTERN...CONFIDENCE IN
FORECAST DETAILS DECREASES DRAMATICALLY BY EARLY NEXT WEEK...
PARTICULARLY WITH REGARD TO THE EVOLUTION OF SOUTHERN STREAM
SHORTWAVE ENERGY PROGRESSING EAST ALONG THE GULF COAST. AT THIS
TIME...WILL STEER THE FORECAST CLOSE TO CLIMATOLOGY. -VINCENT

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 1230 AM WEDNESDAY...

LIFR CEILINGS WILL WORSEN THROUGH THE NIGHT AS VISIBILITIES LOWER AS
WELL. AREAS OF DENSE FOG ARE LIKELY TO DEVELOP OVERNIGHT OR EARLY
WED...AS WARM AND MOIST AIR IS FORCED ATOP A COLD...SATURATED...AND
VERY STABLE LAYER OF AIR NEAR THE SURFACE. CONDITIONS WILL
TRANSITION UP BRIEFLY THROUGH IFR-MVFR RANGE...BEFORE LIKELY
SCATTERING OUT TO VFR ALTOGETHER...AS THE WARM FRONT AT THE SURFACE
FINALLY MAKES INROADS ACROSS CENTRAL NC DURING THE MIDDAY-EARLY
AFTERNOON HOURS AT EASTERN TAF SITES...TO MID-LATE AFTERNOON (IF AT
ALL) AT KINT/KGSO. ANOTHER ISSUE AFTER THE LOW CIGS AND VSBYS LIFT
WILL BE THE INCREASING SW WINDS AT 15-25KT WITH GUSTS TO 30KT
BETWEEN 15Z-23Z.

THEN A COLD FRONT AND ASSOCIATED AREA OF RAIN AND SUB-VFR CONDITIONS
ARRIVE FROM THE NORTHWEST WED NIGHT...AND PERSIST THROUGH THU. A
BRIEF MIX OF SLEET AND/OR FREEZING RAIN WILL BE POSSIBLE BEFORE
PRECIPITATION ENDS LATE THU OR THU EVENING AT KGSO KINT AND KRDU.

OUTLOOK FOR THURSDAY NIGHT INTO SATURDAY: VFR CONDITIONS UNDER HIGH
PRESSURE.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR NCZ007>011-021>028-
038>043-073>078-083>086-088-089.

&&

$$

SYNOPSIS...BADGETT
NEAR TERM...BADGETT
SHORT TERM...BADGETT
LONG TERM...VINCENT
AVIATION...BADGETT


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