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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 021816
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
115 PM EST MON MAR 2 2015

.SYNOPSIS...HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH
THIS AFTERNOON THROUGH TONIGHT...IN THE WAKE OF A COLD FRONTAL
PASSAGE THIS MORNING. HIGH PRESSURE WILL SHIFT OFFSHORE DURING THE
DAY TUESDAY AS A LOW PRESSURE SYSTEM TRACKS NORTHEAST FROM THE
CENTRAL PLAINS INTO THE GREAT LAKES.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 1000 AM MONDAY...

TODAY:

SFC COLD FRONT STARTING TO PROGRESS E-SEWD INTO THE TRIAD...AND
LOOKS TO BE ON SCHEDULE...EXPECTED TO CLEAR THE FORECAST AREA AOA
18Z.  PRECEDING DRYING ALOFT ASSOCIATED WITH BRISK 35-40KT LOW-LEVEL
WESTERLY DOWNSLOPE FLOW EAST OF THE MOUNTAINS...IS HELPING TO MIX
OUT THE LOW CLOUDS/FOG IN ADVANCE OF THE FRONT...WITH NOTABLE BREAKS
IN CLOUD COVER ALREADY SHOWING UP AS FAR EAST AS THE TRIANGLE.
HOWEVER...FULL CLEARING IS NOT EXPECTED UNTIL THE DRIER/COOLER
AIRMASS ADVECTS IN BEHIND THE FRONT THIS AFTERNOON...AND EVEN THIS
WILL BE SHORT-LIVED BEFORE LOW CLOUDS/MOISTURE RUSHES BACK IN
OVERNIGHT. EXPECT HIGHS TO RANGE FROM LOWER 50S NORTH TO
MID/UPPER 50S SOUTH.

TONIGHT: THOUGH DECREASED CLOUD COVER SHOULD BE PRESENT FOR A PERIOD
THIS EVENING...LOW CEILINGS WILL RE-DEVELOP AFTER MIDNIGHT IN
ASSOC/W SOUTHERLY RETURN FLOW /WARM ADVECTION/ AS THE LOW-LEVEL
RIDGE SHIFTS QUICKLY OFFSHORE. IN ADDITION TO STRENGTHENING WARM
ADVECTION...DPVA IN THE FORM OF FAST-MOVING/SMALL AMPLITUDE
SHORTWAVE ENERGY IS EXPECTED TO BE PRESENT BETWEEN 06-12Z TUE... AND
LIGHT PRECIP WILL BE POSSIBLE IN THE WESTERN PIEDMONT AND WESTERN
PORTIONS OF THE SANDHILLS BY SUNRISE TUE. DUE TO THE PROGRESSIVE
NATURE OF THE HIGH BUILDING INTO THE REGION LATER TODAY...THE
AIRMASS IN PLACE TUE MORNING WILL BE LESS CAPABLE OF SUPPORTING
MIXED PTYPE THAN IN THE PREVIOUS EVENT. NEVERTHELESS...A NUISANCE
PERIOD OF LIGHT PL/FZRA CANNOT BE RULED OUT ALONG AND WEST OF
THE HWY 1 CORRIDOR AROUND SUNRISE TUE MORNING. GIVEN ABOVE NORMAL
UNCERTAINTY WITH REGARD TO THE QUALITY OF THE ANTECEDENT AIRMASS AND
EVOLUTION OF PRECIPITATION EARLY TUE MORNING...THE FORECAST WILL
SIMPLE REFLECT A CHANCE OF LIGHT RAIN BETWEEN MIDNIGHT-SUNRISE FROM
THE TRIANGLE WESTWARD. EXPECT LOWS IN THE LOWER TO MID 30S. -VINCENT

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 200 AM MONDAY...

TUE: A PRONOUNCED COLD AIR DAMMING WEDGE WILL BE IN PLACE TUE...WITH
PERIODS OF DRIZZLE OR LIGHT RAIN POSSIBLE THROUGHOUT THE DAY IN
ASSOC/W MODEST (ALBEIT STEADY) WARM ADVECTION...THOUGH LITTLE IF ANY
UPPER LEVEL FORCING IS ANTICIPATED AT THIS TIME. EXPECT HIGHS WELL
BELOW NORMAL IN THE LOWER/MID 30S (NW) TO MID/UPPER 30S ELSEWHERE.
TEMPS COULD VARY A GOOD 4-7F FROM THIS FORECAST IF LIGHT PRECIP (AND
ASSOC EVAP COOLING) DO NOT OCCUR AS ANTICIPATED.

TUE NIGHT: LOWS WED MORNING WILL LIKELY OCCUR AT MIDNIGHT IN MOST
AREAS. A WARM FRONT IS EXPECTED TO LIFT NORTHWARD TOWARD CENTRAL NC
TUE NIGHT...HOWEVER...GIVEN AN UNAMPLIFIED PATTERN...RELATIVELY WEAK
MSLP/HEIGHT GRADIENT AND THE LACK OF A WELL DEFINED UPSTREAM
CYCLONE...IT SHOULD BE DIFFICULT FOR THE WARM FRONT TO MAKE MUCH
PROGRESS THROUGH THE CAD WEDGE IN PLACE ACROSS CENTRAL NC.
SLOW/STEADY PROGRESS INTO THE SANDHILLS AND COASTAL PLAIN SHOULD
RESULT IN RISING TEMPS AFTER MIDNIGHT IN MOST LOCATIONS...THOUGH
PERHAPS REMAINING STEADY IN THE MID/UPPER 30S ACROSS THE N/NW
PIEDMONT WITH ONLY A SLIGHT RISE TO NEAR 40F IN THE TRIANGLE BY
SUNRISE WED. SOUTHERN PORTIONS OF THE SANDHILLS AND COASTAL PLAIN
ARE MOST LIKELY TO SEE TEMPERATURES RISING INTO THE MID/UPPER 40S
AND PERHAPS LOWER 50S BY SUNRISE WED. -VINCENT

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 323 AM MONDAY...

THE LATEST MODEL RUNS AND CURRENT TRENDS IN THE MODELS SUGGEST THAT
THE NEXT ARCTIC FRONT WILL BE DELAYED SOMEWHAT FROM PREVIOUS
FORECASTS. THIS DOES HAVE IMPLICATIONS ON THE CURRENT FORECAST FOR
WEDNESDAY INTO FRIDAY. WEDNESDAY IS STILL EXPECTED TO BE THE WARMEST
DAY WITH A BROAD SOUTHWEST FLOW OUT AHEAD OF THE FRONT THAT WILL
LIKELY BECOME STALLED ALONG THE WESTERN SLOPES OF THE MOUNTAINS LATE
WEDNESDAY INTO WEDNESDAY NIGHT. AT LEAST PARTIAL SUNSHINE IN THE SW
FLOW IN THE WARM SECTOR WOULD YIELD HIGHS IN THE UPPER 60S TO MID
70S NW TO SOUTH ON WEDNESDAY.

FOR WEDNESDAY NIGHT AND THURSDAY... THE ARCTIC FRONT IS FORECAST TO
SLIP THROUGH CENTRAL NORTH CAROLINA LATE WEDNESDAY NIGHT AND
THURSDAY FROM THE NORTH. THE PARENT HIGH IS PROGGED TO BE STRONG
(1035 MB OR SO)... BUT OVER THE UPPER MIDWEST... THUS THE COLD AIR
SHOULD BE SHALLOW AND INITIALLY BLOCKED BY THE CENTRAL APPALACHIANS.

IT WOULD NOT BE UNTIL THURSDAY (AND POSSIBLY DELAYED EVEN MORE)
BEFORE A POTENTIAL LINGERING FRONTAL WAVE WOULD FOCUS RAIN BEHIND
THE FRONT... WHICH COULD POSSIBLY CHANGE TO A WINTERY MIXTURE ACROSS
THE NORTHWEST OR NORTHERN PIEDMONT. REGARDLESS... WHAT IS DIFFERENT
FROM THIS WINTER P-TYPE POTENTIAL IS AT LEAST TWO FOLD... 1) THE
CHANGE OVER (IF IT OCCURS AT ALL - WOULD BE AFTER RAIN FALLS FOR A
GOOD LONG PERIOD OF TIME LATE WEDNESDAY NIGHT AND THURSDAY... 2) THE
TEMPERATURES WOULD START IN THE 50S/60S WEDNESDAY NIGHT... BEFORE
FALLING INTO THE 30S/40S THURSDAY... AND 3) THE WARMTH PRECEDING THE
POTENTIAL EVENT (HIGHS IN THE 70S WEDNESDAY)... WILL BE ANYTHING BUT
WHAT WE HAVE SEEN LEADING UP TO THE RECENT (COLD) WINTER WEATHER
EVENTS. THEREFORE... THIS SYSTEM APPEARS THAT IT WOULD LIKELY NOT
POSE A SIGNIFICANT THREAT AT THE CURRENT TIME.

SENSIBLE WEATHER AS IT CURRENTLY LOOKS... WARM AND PARTLY SUNNY
WEDNESDAY. HIGHS GENERALLY 70-77. BECOMING CLOUDY EAST WITH RAIN
LIKELY WEST WEDNESDAY NIGHT. LOWS 50S/60S... FALLING INTO THE 40S
NORTHERN PIEDMONT TOWARD 12Z/THU. THURSDAY... RAIN LIKELY.
TEMPERATURES FALLING INTO THE MID 30S TO MID 40S. RAIN ENDING
POSSIBLY BRIEFLY AS A WINTERY MIXTURE IN THE NORTH AND NORTHEAST
THURSDAY NIGHT. LOWS IN THE 20S. FRIDAY THROUGH SUNDAY... PARTLY
CLOUDY. COLDER. LOWS IN THE 20S. HIGHS IN THE 30S TO LOWER 40S
FRIDAY... AND IN THE 40S SAT... THEN 50S SUNDAY.

THIS IS STILL A LOW CONFIDENCE FORECAST FOR PRECIPIATION TYPE
THURSDAY INTO THURSDAY NIGHT. IF THE ARCTIC FRONT CAN PUSH THROUGH
EARLY THURSDAY... AND A MORE SIGNIFICANT WAVE CAN DEVELOP ALONG THE
FRONT AS THE COLD AIR IS PUSHING IN FROM THE NORTH... THEN MORE IN
THE WAY OF SNOW/SLEET MAY FALL THAN IS CURRENTLY THOUGHT... MAINLY
ACROSS THE NORTHERN PIEDMONT. HOWEVER... CONFIDENCE IS LOWERED IN
ACCUMULATIONS THAT WOULD BE ANTICIPATED DUE TO TIMING (MAINLY
AFTERNOON)... THE EXPECTED WARMTH AND RAIN PRECEDING THE FRONT...
AND THE WARMING SOIL TEMPS.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 115 PM MONDAY...

24-HR TAF PERIOD:

A STRONG BUT TRANSIENT +1030MB SURFACE HIGH WILL BUILD EAST ACROSS
THE AREA THIS AFTERNOON AND TONIGHT IN THE WAKE OF THE COLD FRONT
PASSAGE EARLIER TODAY. DRY AIR ADVECTION ALONG AND BEHIND THE FRONT
HAS RESULTED IN VFR CONDITIONS ACROSS THE AREA. WILL SEE NWLY WIND
GUSTS INTO THE UPPER TEENS IMMEDIATELY BEHIND THE FRONT...BECOMING
LIGHT THIS EVENING FROM THE EAST-NORTHEAST.

AVIATION CONDITIONS WILL QUICKLY DETERIORATE TONIGHT...ESPECIALLY
ACROSS THE WESTERN PIEDMONT(KINT AND KGSO)WITH MVFR/IFR CEILINGS
RETURNING BETWEEN MIDNIGHT AND SUNRISE TUE MORNING AS THE SFC HIGH
MOVES QUICKLY OFFSHORE...ALLOWING LOW-LEVEL SOUTHERLY RETURN FLOW TO
DEVELOP WITH PATCHY LIGHT RAIN/DZ. ITS POSSIBLE THAT AREAS ALONG AND
NEAR THE NC/VA BORDER MAY SEE A BRIEF PERIOD OF FREEZING
RAIN/DRIZZLE TUESDAY MORNING...BEFORE CHANGING OVER TO A COLD RAIN
THEREAFTER AS TEMPERATURES WARM INTO THE LOWER/MID 30S.

CONFIDENCE IS MUCH LOWER AT KRDU...KRWI...KFAY...WHERE THERE IS A
LARGE SPREAD IN THE MODEL GUIDANCE. SOME MODEL GUIDANCE SUGGESTS
SOME THAT THE EAST-NORTHEASTERLY FLOW COULD SPREAD STRATUS INTO THE
AREA  BETWEEN 00-06Z. OTHER MODELS INDICATE THAT CEILINGS WILL
REMAIN IN THE LOW END VFR RANGE OVERNIGHT(4-5KT)....EVENTUALLY
BECOMING SUB-VFR NEAR THE END OF THE TAF PERIOD IN ASSOCIATION WITH
COLD AIR DAMMING AS THE WARM MOIST ADVECTION SPREADS EASTWARD
AS THE HIGH SHIFTS OFFSHORE.

LOOKING AHEAD: ADVERSE AVIATION CONDITIONS (IFR TO MVFR /LIFR
CEILINGS AND RAIN) ASSOC/W A PRONOUNCED COLD AIR DAMMING WEDGE WILL
PREVAIL TUESDAY AFTERNOON ... WITH SOME IMPROVEMENT IN CEILINGS
POSSIBLE AT SOUTHERN TERMINALS LATE TUE NIGHT AS A WARM FRONT LIFTS
NORTHWARD THROUGH THE CAROLINAS. ADVERSE AVIATION CONDITIONS ARE
LIKELY TO PREVAIL THE REMAINDER OF THE WEEK. -VINCENT

&&

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

&&

$$

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