127
FXUS62 KRAH 161625
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1224 PM EDT WED OCT 16 2013
.SYNOPSIS...
A WEAK COLD FRONT WILL APPROACH THE MOUNTAINS FROM THE WEST
TONIGHT...THEN TRACK EAST THROUGH THE REGION ON THURSDAY AND
THURSDAY NIGHT. HIGH PRESSURE WILL BUILD INTO THE AREA IN THE WAKE
OF THE FRONT ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1215 PM WEDNESDAY...
A DEAMPLIFYING UPPER LEVEL LOW OVER THE GREAT LAKES WILL TRACK
NORTHEAST INTO CANADA TODAY/TONIGHT...WHILE ANOTHER UPPER LEVEL LOW
CURRENTLY IN COLORADO WILL TRACK EAST THROUGH THE CENTRAL PLAINS
INTO THE CENTRAL MS RIVER VALLEY BY 12Z THU. THE LINGERING SFC/UPPER
LEVEL LOW OFFSHORE THE CAROLINA COAST WILL FURTHER WEAKEN TODAY. AS
THE OFFSHORE LOW CONTINUES TO WEAKEN...LOW-LEVEL NORTHEAST FLOW OVER
THE CAROLINAS WILL ALSO WEAKEN TODAY...EVENTUALLY BECOMING SOUTHWEST
LATE THIS AFTERNOON INTO TONIGHT. GIVEN WIDESPREAD STRATUS ACROSS
THE AREA THIS MORNING AND ONLY A GRADUAL CHANGE IN THE SPEED/
DIRECTION OF LOW-LEVEL FLOW TODAY...ANTICIPATE THAT CLOUD COVER WILL
TAKE QUITE A WHILE TO ERODE...PERHAPS UNTIL LATE AFTERNOON TO EARLY
EVENING IN SOME AREAS ALONG/EAST OF HWY 1. IF THIS IS THE CASE...
HIGHS MAY BE A FEW DEGREES COOLER THAN PREVIOUSLY ANTICIPATED...
ESPECIALLY ALONG/EAST OF HWY 1. WILL INDICATE HIGHS IN THE LOWER/MID
70S. LOWS TONIGHT WILL BE TEMPERED BY INCREASING MID/UPPER LEVEL
CLOUD COVER AND PERHAPS LINGERING LOW-LEVEL CLOUD COVER ALONG/EAST
OF HWY 1. WILL INDICATE LOWS IN THE UPPER 50S TO LOWER 60S. GIVEN NO
FORCING THROUGHOUT THE COLUMN...EXPECT NO CHANCE FOR PRECIP. -VINCENT
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
AS OF 1220 PM WEDNESDAY...
THE UPPER LOW PROGRESSING EAST INTO THE CENTRAL MS RIVER VALLEY
TONIGHT WILL LIFT NORTHEAST INTO THE OH VALLEY/GREAT LAKES DURING
THE DAY THU...THEN PROGRESS INTO NEW ENGLAND TONIGHT. A SFC-925 MB
TROUGH/COLD FRONT ATTENDANT THE UPPER LEVEL WAVE WILL TRACK EAST
INTO WESTERN PORTIONS OF THE CAROLINAS ON THU...THEN SLOW DOWN AS IT
PROGRESSES EAST THROUGH CENTRAL NC THU EVENING/NIGHT. THERE WILL BE
LITTLE CHANCE FOR MEANINGFUL LOW-LEVEL MOISTURE RETURN IN ADVANCE OF
THE FRONT ON THU...THOUGH MID/UPPER LEVEL MOISTURE WILL CERTAINLY
INCREASE WITH PWAT VALUES INCREASING FROM 1.10" TODAY TO 1.50-1.75"
TONIGHT/THU. WITH WEAK MID-LEVEL LAPSE RATES...RELATIVELY LACKLUSTER
LOW-LEVEL MOISTURE...AND DECREASED INSOLATION ASSOCIATED WITH
WIDESPREAD CLOUD COVER...THERE WILL BE LITTLE IF ANY DIURNAL
DESTABILIZATION. FORCING FOR ASCENT WILL BE PRESENT IN THE FORM OF
SHALLOW LOW-LEVEL CONVERGENCE LATE THU INTO THU NIGHT...THOUGH UPPER
LEVEL FORCING WILL LARGELY BE NEGLIGIBLE GIVEN THE TRACK OF THE
UPPER LEVEL WAVE (WELL N/NW OF CENTRAL NC). THE LATEST MODEL
GUIDANCE HAS TRENDED A BIT DRIER THU/THU NIGHT...WITH THE OVERALL
BEST CHANCE OF ISOLD TO SCT SHOWERS IN THE NW PIEDMONT THU AFTERNOON
AND EVENING. WILL INDICATE PRECIP CHANCES RANGING FROM 40-50% IN THE
NW PIEDMONT TO 20-30% ELSEWHERE. HIGHS THU WILL DEPEND ON CLOUD
COVER AND WHETHER OR NOT ANY SHOWER ACTIVITY DEVELOPS OR MOVES INTO
THE WESTERN PIEDMONT DURING THE LATE AFTERNOON. GIVEN INCREASED
THICKNESSES ASSOCIATED WITH WEAK WARM ADVECTION VIA SOUTHWEST FLOW
IN THE LOWER-LEVELS...EXPECT HIGHS RANGING FROM THE LOWER/MID 70S IN
THE FAR NW PIEDMONT (MORE CLOUD COVER) TO UPPER 70S OR PERHAPS LOWER
80S IN THE EAST. LOWS THU NIGHT WILL DEPEND PRIMARILY ON THE
PROGRESS OF THE SFC FRONT AND THE ONSET/DURATION OF COLD ADVECTION
PRIOR TO SUNRISE. WILL INDICATE LOWS RANGING FROM THE LOWER/MID 50S
IN THE NW TO LOWER 60S IN THE SE. -VINCENT
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 1220 PM WEDNESDAY...
IN A VERY TIMELY TURN OF EVENTS...IT APPEARS THAT THE FIRST REAL
TASTE OF FALL MAY BE JUST AROUND THE CORNER. THE MODELS HAVE BEEN
COMING INTO AGREEMENT IN FORECASTING A PATTERN CHANGE THIS WEEKEND
INTO NEXT WEEK... WITH THE DEVELOPMENT OF A DEEP TROUGH OVER THE
EASTERN PART OF THE UNITED STATES. IN ADDITION... AN ACTIVE
SUBTROPICAL JET IS EXPECTED FROM THE GULF OF MEXICO NE ACROSS
FLORIDA TO OFF THE SC COAST. THE WAVES ALONG THE BOUNDARY WILL HAVE
TO BE WATCHED... WITH AT LEAST SOME RAIN POTENTIAL ESPECIALLY OVER
THE SE ZONES SAT-EARLY SUNDAY.
OVERALL...THIS PATTERN HAS A MUCH MORE WINTER-LIKE LOOK FOR THE
GREAT LAKES SOUTHWARD TOWARD OUR REGION EARLY NEXT WEEK. THE FIRST
CHILLY SURFACE HIGH PRESSURE IS FORECAST TO REACH THE MID-ATLANTIC
REGION SUNDAY NIGHT INTO MONDAY. THERE MAY BE SOME MID TO UPPER 30S
IN THE NW PIEDMONT BY MONDAY MORNING. PROJECTIONS INDICATE THAT
TEMPERATURES SHOULD REMAIN JUST ABOVE THE FROST THRESHOLD FOR MONDAY
MORNING. THIS SHOULD BE FOLLOWED BY ANOTHER SHOT OF CHILLY AIR BY
WED-THU. THERE SHOULD BE SOME FROST THREAT WITH THIS NEXT SHOT OF
CHILLY AIR BY THU OR FRI... JUST ABOUT CLIMATOLOGICAL AVERAGE FOR
THE FIRST FROSTS OF THE SEASON IN THE PIEDMONT.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 1215 PM WEDNESDAY...
MVFR CEILINGS WILL PERSIST THROUGH THE MAJORITY OF THE AFTERNOON IN
MOST LOCATIONS...WITH CEILINGS RANGING FROM 1000-3000 FT AGL. EXPECT
CEILINGS TO GRADUALLY LIFT AND SCATTER OUT TO VFR BETWEEN 21Z THIS
AFTERNOON AND 03Z TONIGHT AS LOW-LEVEL FLOW BECOMES SOUTHWESTERLY
AND ADVECTS A DRIER AIRMASS INTO THE REGION. HOWEVER...IF THE
EROSION OF CLOUD COVER IS DELAYED UNTIL SUNSET OR LATER...MOISTURE
IN THE LOWEST LEVELS MAY BE SUFFICIENT FOR SUB-VFR FOG AND/OR
STRATUS TO DEVELOP OVERNIGHT...ESPECIALLY AT RDU/FAY/RWI.
OTHERWISE...EXPECT VFR CONDITIONS FROM SUNRISE THROUGH EARLY THU
AFTERNOON WITH MID LEVEL CEILINGS LOWERING TO 3000-4000 FT AGL AT
THE INT/GSO TERMINALS AS A WEAK COLD FRONT APPROACHES FROM THE WEST.
LOOKING AHEAD:
ANTICIPATE A POTENTIAL FOR MVFR CONDITIONS AND SHOWERS ASSOCIATED
WITH A WAVE OF LOW PRESSURE EXPECTED TO DEVELOP ALONG THE COLD FRONT
PROGRESSING INTO THE REGION FROM THE WEST THU AFTERNOON THROUGH THU
NIGHT. SUB-VFR CEILINGS MAY PERSIST AT EASTERN TERMINALS (FAY/RWI)
DURING EARLY PORTIONS OF THE DAY ON FRIDAY AS THE FRONT STALLS OUT
ALONG OR JUST OFFSHORE THE CAROLINA COAST. UNCERTAINTY REMAINS HIGH
FOR THE FORECAST THIS WEEKEND. AT THIS TIME...EXPECT A POTENTIAL FOR
SUB-VFR CONDITIONS ASSOC/W RAIN...PRIMARILY AT THE EASTERN TERMINALS
SAT INTO SAT NIGHT. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT
LONG TERM...BADGETT
AVIATION...VINCENT