Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 052006
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
305 PM EST THU MAR 5 2015

.SYNOPSIS...PRECIPITATION WILL DIMINISH WEST-TO-EAST THIS EVENING.
ARCTIC HIGH PRESSURE WILL BUILD INTO THE AREA ON FRIDAY AND SETTLE
OVER THE REGION FRIDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 305 PM THURSDAY...

STRONG COLD FRONT ABOUT TO EXIT THE FAR SOUTH-SE SECTOR OF CENTRAL
NC. THE PASSAGE OF THE FRONT IS PRODUCING VERY STRONG WIND GUSTS
WITH 40-45KT GUSTS BEING REPORTED AT KFAY...KCLT...KAFP AND KRCZ.
EXPECT SIMILAR GUSTS TO OCCUR SHORTLY AT KMEB AND KCTZ. IN
ADDITION...SEEING TEMPERATURES FROP 20-25 DEGREES IMMEDIATELY BEHIND
THE FRONT...AND 30-35 DEGREES WITHIN A FEW HOURS AFTER FRONTAL
PASSAGE.

THE PASSAGE OF THE 850MB TROUGH LATE THIS AFTERNOON-EARLY EVENING
SHOULD INITIATE THE CHANGEOVER OF RAIN TO RAIN/SLEET MIX THEN TO
MOSTLY SLEET...BEFORE ENDING AS SLEET/SNOW/FREEZING RAIN OR VERY
LIGHT SNOW. THIS OCCURRENCE MORE LIKELY ACROSS THE NORTHERN THIRD.
FOR AREAS SOUTH OF HIGHWAY 64...EXPECT RAIN UNTIL 7-9 PM THEN A
BRIEF PERIOD OF RAIN MIXED WITH SLEET BEFORE THE PRECIP ENDS.

EXPECT SLEET ACCUMULATION OF LESS THAN A HALF INCH IN VICINITY OF
THE VA BORDER...MORE SO TOWARDS WARRENTON AND ROANOKE RAPIDS AND
SCOTLAND NECK...WITH LIGHTER AMOUNTS (0.20 OF AN INCH OR LESS)
TOWARDS THE TRIAD AND TRIANGLE AREAS. THE DEPTH OF THE COLD NOSE
ABOVE THE SURFACE WILL DETERMINE WHERE ANY FREEZING RAIN OCCURS.
CONSECUTIVE MODEL RUNS HAVE BEEN GRADUALLY EXPANDING THE DEPTH OF
THE COLD NOSE...SUGGESTING MORE OF A SLEET THREAT VERSUS FREEZING
RAIN. IF THE COLD NOSE DEPTH TURNS OUT TO BE LESS THAN
EXPECTED...THEN FREEZING RAIN MORE BE MORE OF AN ISSUE. EVEN
SO...ICE ACCRUAL EXPECTED TO BE NO MORE THAN A TENTH OF AN INCH.

SO WILL LEAN MORE TOWARD SLEET WITH THIS FORECAST PACKAGE RATHER
THAN FREEZING RAIN. AFTER 00Z...ATMOSPHERE BEGINS TO DRY OUT ALOFT
AND LIFTING MECHANISM FOR PRECIP BEGINS TO WANE AS STRONG UPPER
LEVEL JET (ANALYZED OVER 200KTS OFF THE COAST OF MAINE AT 12Z) MOVES
FARTHER AWAY FROM OUR REGION. THIS SHOULD LEAD TO A MIXED BAG OF
WINTRY PRECIP ACROSS THE NORTH HALF THROUGH 03Z-04Z BEFORE PRECIP
DIMINISHES.

AFTER 04Z...ATTENTION WILL TURN TOWARD THE PLUMMETING TEMPS AND
RESIDUAL MOISTURE LEFT ON THE ROADWAYS. TEMPS BY MIDNIGHT SHOULD BE
AT OR BELOW FREEZING ACROSS THE NORTH HALF...AND NEAR 20 FAR NORTH
TO THE UPPER 20S/NEAR 30 FAR SOUTH BY 5 AM. THIS COLD AIR MASS
SHOULD CAUSE WHAT WATER IS LEFT ON THE ROAD SURFACE TO
FREEZE...LEADING TO BLACK ICE CONDITIONS. EXPECT WIDESPREAD BLACK
ICE CONDITIONS ACROSS THE NORTH HALF WHILE THE BLACK ICE MAY BE MORE
SPOTTY THE FARTHER SOUTH ONE GOES. PLAN TO ISSUE A WINTER WEATHER
ADVISORY...STARTING AT MIDNIGHT...TO COVER THE BLACK ICE THREAT.
TEMPERATURES PROJECTED TO REMAIN BELOW FREEZING UNTIL LATE
MORNING/MID DAY ACROSS MOST OF THE FORECAST AREA.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 140 PM THURSDAY...

HIGH PRESSURE WILL BUILD INTO THE AREA ON FRIDAY...AND REMAIN
OVERHEAD THROUGH THE WEEKEND...RESULTING IN DRY WEATHER. CLEARING
SKIES AND DECREASING WINDS ON FRIDAY...BECOMING CLEAR AND CALM
OVERNIGHT AND THROUGH SATURDAY NIGHT. FRIDAY WILL BE COOL...WITH
HIGHS IN THE MID 30S NORTHEAST TO LOW 40S SOUTHWEST AND OVERNIGHT
LOWS IN THE UPPER TEENS TO MID 20S. TEMPERATURES WILL BEGIN TO
MODERATE ON SATURDAY...HIGHS MAINLY IN THE LOW TO MID 50S AND LOWS
IN THE LOW 30S. CLOUDS WILL BUILD BACK IN AGAIN ON SUNDAY AS WARM
MOIST AIR BEGINS TO ADVECT IN FROM THE SOUTHWEST. NEAR SEASONAL
TEMPERATURES WILL RETURN BY SUNDAY...HIGHS IN THE MID 50S TO LOW 60S
AND LOWS IN THE UPPER 30S TO LOW 40S...ALTHOUGH THE CHANCES FOR SOME
LIGHT RAIN WILL ALSO INCREASE SUNDAY NIGHT INTO MONDAY.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 140 PM THURSDAY...

SPLIT FLOW REGIME CONTINUES TO CAUSE CONSIDERABLE RUN TO RUN
VARIATION IN MODEL SOLUTIONS FOR THE LONGER RANGE FORECAST. A WEAK
NORTHERN STREAM FRONT WILL BE MOVING ACROSS THE AREA ON MONDAY...
WHICH WOULD ENCOUNTER DEEPER MOISTURE ACROSS THE SOUTHEAST WITH
SCATTERED SHOWERS LATE MONDAY INTO MONDAY NIGHT. INCREASING POPS
WOULD BE SPREADING BACK INTO THE WEST TUESDAY INTO WEDNESDAY AS THE
FRONT STALLS ALONG THE COAST WITH SURFACE WAVES DEVELOPING AND
RIDING NORTHEAST UP THE FRONTAL ZONE. TEMPERATURES TUESDAY WOULD
TAKE A HIT WITH SURFACE WAVE DEVELOPMENT ENHANCING IN SITU
DAMMING...AND HIGHS WILL STALL IN THE 50S... PERHAPS A BIT LOWER IF
THE LOW LEVEL FEATURES ALLOWS FOR A MORE FAVORABLE DAMMING FEATURES
TO ALIGN.

CONFIDENCE FALLS OFF FURTHER IN THE WED AND THU PERIODS DUE TO
QUESTIONABLE INTERACTIONS BETWEEN THE NORTHERN AND SOUTHERN STREAM
SYSTEMS. AT THIS POINT...WILL INTRODUCE A SLIGHT CHANCE POP WITH
HIGHS AROUND 60 BOTH DAYS.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 1255 PM THURSDAY...

24-HOUR TAF PERIOD: LINGERING VFR CONDITIONS AND SOUTHWEST FLOW
ACROSS THE SOUTH WILL CHANGE TO MVFR THEN IFR AND GUSTY NORTHERLY
FLOW AS THE FRONT PUSHES THROUGH. LOCATIONS BEHIND THE FRONT
CONTINUE TO EXPERIENCE GUSTY WINDS AND IFR CIGS AND VISBYS WITH
LIGHT TO MODERATE RAIN. THESE CONDITIONS ARE EXPECTED TO CONTINUE
THROUGH THIS EVENING...LONGEST AT KFAY...BEGINNING TO TAPER OFF
AROUND MIDNIGHT. A BRIEF CHANGEOVER FROM RAIN TO RAIN/SLEET AND THEN
RAIN/SLEET/SNOW IS LIKELY ACROSS THE NORTHERN HALF OF CENTRAL NC
TOWARD THE TAIL END OF THE PRECIP...WITH THE GREATEST CHANCES IN THE
NORTHEAST. EXPECT IMPROVING CONDITIONS OVERNIGHT AS THE PRECIP COMES
TO AN END. MOST...IF NOT ALL...OF CENTRAL NC SHOULD BE VFR BY
SUNRISE...OR SHORTLY THEREAFTER AND WINDS SHOULD BE NORTHERLY AND
SLOWLY DECREASING IN SPEED THROUGHOUT THE DAY.

LOOKING AHEAD: HIGH CONFIDENCE THAT VFR CONDITIONS WILL PERSIST
THROUGH THE WEEKEND ACROSS CENTRAL NC AS HIGH PRESSURE BUILDS IN AND
REMAINS OVER THE REGION. THE NEXT CHANCE FOR SUB-VFR CONDITIONS WILL
BE DURING THE OVERNIGHT HOURS SUNDAY NIGHT AND MONDAY NIGHT AS MORE
WARM MOIST AIR ADVECTS INTO CENTRAL NC.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON EST FRIDAY FOR NCZ007>011-021>028-
038>043-078.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST FRIDAY
FOR NCZ073>077-083>086-088-089.

&&

$$

SYNOPSIS...WSS
NEAR TERM...WSS
SHORT TERM...KC
LONG TERM...MLM
AVIATION...KC



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