Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 060047 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 747 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 /00Z THURSDAY THROUGH TUESDAY/...
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AS OF 740 PM THURSDAY... 24-HOUR TAF PERIOD: WARM MOIST AIR CONTINUES TO OVERRIDE COLD SURFACE HIGH PRESSURE ACROSS CENTRAL NC THIS EVENING... ALLOWING OR GENERALLY MVFR TO IFR CIGS. SEVERAL BANDS OF GENERALLY LIGHT PRECIP ARE MOVING ACROSS THE AREA CURRENTLY AS WELL. PRECIP MAY MIX OR TURN TO SOME LIGHT SNOW OR SLEET AT KGSO/KINT/KRDU/KRWI THIS EVENING BEFORE ENDING BY GENERALLY MIDNIGHT OR SO. GIVEN THE EXPECTED LIGHT PRECIP THINK VISBYS SHOULD REMAIN MVFR OR BETTER THIS EVENING WITH ANY PRECIP. IN ADDITION... AS THE STRONG SURFACE HIGH CONTINUES TO BUILD INTO THE AREA WE WILL SEE A NORTH TO NORTHEASTERLY WIND IN THE 9 TO 14 KT RANGE... WITH GUSTS AS HIGH AS 20 TO 22 KTS OVERNIGHT. DRIER AIR ALOFT IS EXPECTED TO SPREAD INTO THE REGION AFTER MIDNIGHT... WITH VFR CONDITIONS EXPECTED TO RETURN TO THE AREA BY GENERALLY 09 TO 12Z. HOWEVER... WE COULD SEE SOME LINGERING AREAS OF MVFR CIGS AT KRWI/KFAY/KRDU UNTIL AS LATE AS 15Z... WITH EVEN A FEW AREAS OF SCATTERED CLOUD COVER AT KGSO/KINT AT AROUND 2500FT DURING THE MID MORNING HOURS AS WELL. MOSTLY SUNNY SKIES AND VFR CONDITIONS ALONG WITH DECREASING WINDS ARE EXPECTED ACROSS CENTRAL NC BY MID TO LATE MORNING... AND CONTINUING FOR THE REST OF THE DAY. OUTLOOK: 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.
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&& .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...BSD/KC

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