Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS62 KRAH 182347
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
747 PM EDT SAT OCT 18 2014

.SYNOPSIS....ANOTHER DRY COLD FRONT WILL CROSS CENTRAL NC THIS
EVENING. HIGH PRESSURE WILL BUILD INTO OUR AREA SUNDAY AND SETTLE
OVERHEAD SUNDAY NIGHT THEN DRIFT EAST ON MONDAY.

&&

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

A S/W DIGGING ON THE BACK SIDE OF A L/W OVER THE NORTHERN MID
ATLANTIC-SOUTHERN NEW ENGLAND WILL CROSS CENTRAL NC THIS
EVENING...EXITING OUR REGION PRIOR TO DAYBREAK. THIS FEATURE MAY
ENHANCE MID LEVEL CLOUDINESS ACROSS THE REGION AS WELL AS MAINTAIN A
LIGHT BUT STEADY N-NW WIND. MOISTURE CONFINED TO A RELATIVELY
NARROW LAYER SO NOT EXPECTING MUCH IN THE MANNER OF PRECIP. PASSAGE
OF THE MID LEVEL TROUGH WILL INCREASE LOW LEVEL COLD AIR ADVECTION
LATER TONIGHT...SENDING OVERNIGHT TEMPS INTO THE 40S.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 305 PM SATURDAY...

SUNDAY...SFC HIGH PRESSURE WILL BUILD INTO THE REGION WHILE
SUBSIDENCE IN THE WAKE OF THE EXITING S/W WILL RESULT IN SUNNY
SKIES. 850MB TROUGH PROJECTED TO LIE ACROSS THE REGION. LOW LEVEL
THICKNESSES WILL AVERAGE 20M BELOW NORMAL...YIELDING HIGH TEMPS
ABOUT 5-7 DEGREES BELOW NORMAL. MAX TEMPS EXPECTED TO RANGE FROM THE
MID-UPPER 60S NORTH TO NEAR 70 SOUTH.

SUNDAY NIGHT...HIGH PRESSURE WILL RESIDE OVERHEAD INITIALLY THEN
DRIFT EAST TOWARD DAYBREAK. UNDER THE CLEAR SKIES AND LIGHT/CALM
WIND REGIME...TEMPS SHOULD PLUMMET AFTER SUNSET INTO THE 40S. A S/W
APPROACHING CENTRAL NC IN THE WLY FLOW ALOFT MAY SPREAD HIGH LEVEL
CLOUDS ACROSS CENTRAL NC PRIOR TO DAYBREAK. STILL SOME UNCERTAINTY
AS TO THE COVERAGE/THICKNESS OF THIS CLOUD SHIELD. A THICKER CLOUD
COVER WILL AID TO KEEP TEMPS UP WHILE A THINNER LAYER WILL NOT HAVE
AN EFFECT ON RADIATIONAL COOLING AT THE SURFACE. SINCE GFS HAS A
TENDENCY TO BE TOO WET ALOFT (IT`S CURRENTLY VERY BULLISH ON THE
VEIL OF HIGH CLOUDS LATE SUNDAY NIGHT)...CURRENT THINKING ID THAT
WHAT HIGH CLOUDS ARE THERE WILL BE THIN. THUS...EXPECT MIN TEMPS TO
RANGE FROM THE UPPER 30S-LOWER 40S WITH MID 30S IN THE NORMALLY
COLDER LOCATIONS. WHERE TEMPS REACH COLDER THAN 37 DEGREES...COULD
SEE SPOTTY LIGHT FROST.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 240 PM SATURDAY...

FOR MON-TUE: AFTER A BIT OF A COOL START MON... TEMPS SHOULD REBOUND
NICELY AS THICKNESSES START TO CLIMB BACK UP TOWARD NORMAL. THE
SURFACE HIGH CENTERED OVER ERN NC/ERN VA WILL MOVE SWIFTLY EAST AND
OFF THE COAST... FOLLOWED BY A CONFLUENT BUT LIGHT S/SW FLOW INTO
NC. CIRCULATION AROUND A LARGE SURFACE LOW PRESSURE AREA COVERING
MUCH OF THE GULF AND ADJACENT MEXICO WILL LIMIT MOISTURE RETURN INTO
THE AREA... SO EXPECT DRY WEATHER MON... BUT WITH INCREASING CLOUDS.
A POTENT CLIPPER WAVE OVER THE UPPER MIDWEST SUN NIGHT WILL DROP
SOUTH AND SE... HELPING TO CARVE OUT ANOTHER ROUND OF DEEP TROUGHING
OVER ERN NOAM... AS AN ASSOCIATED SURFACE FRONT APPROACHES FROM THE
NW MON NIGHT. THE INCREASING DPVA AND MID LEVEL SPEED MAX OVER NC
WILL BE ACCOMPANIED BY A MODEST UPPER DIVERGENCE MAX IN THE RRQ/LFQ
OF 80+ KT JETS TO OUR NE/SW RESPECTIVELY. BUT THIS ASCENT MAY NOT BE
ENOUGH TO OVERCOME THE LIMITED MOISTURE AS PW VALUES ARE PROJECTED
TO BARELY REACH NEAR NORMAL AHEAD OF THE CLIPPER FRONT. A SERIES OF
WEAK SURFACE TROUGHS ARE EXPECTED TO SWING THROUGH CENTRAL NC MON
NIGHT THROUGH TUE WITH INCREASINGLY CYCLONIC FLOW ALOFT... WITH THE
MAIN FRONT TIMED BY THE GFS/ECMWF TO DROP THROUGH THE AREA TUE
NIGHT... AS THE DIGGING TROUGH CULMINATES IN A CLOSED LOW OVER THE
MIDATLANTIC REGION (WITH THE ECMWF FARTHER SOUTH INTO NC THAN THE
GFS). BALANCING THE STRENGTHENING DYNAMICS AND KINEMATICS WITH WHAT
SHOULD AMOUNT TO JUST SHALLOW MOISTURE AND MUCAPE OF LESS THAN 200
J/KG... WILL KEEP POPS NO WORSE THAN SLIGHT CHANCE TUE AFTERNOON AND
NIGHT MAINLY ACROSS THE FAR NORTH AND EAST. THE SW CWA HAS THE BEST
CHANCE OF STAYING DRY DUE TO ITS MORE PROFOUND INFLUENCE OF
DOWNSLOPE FLOW. EXPECT HIGHS JUST SLIGHTLY BELOW NORMAL MON... 67-
72... AND A TAD MILDER TUE (68-74) WITH MINOR WARMING AHEAD OF THE
FRONT. SLIGHTLY ABOVE NORMAL LOWS BOTH NIGHTS 47-53 AS THE LOW
LEVELS REMAIN A BIT STIRRED OVERNIGHT.

FOR WED THROUGH SAT: DRY AND FAIRLY SEASONABLE WEATHER PERSISTS. THE
CLOSED MID LEVEL LOW WILL POSSESS SOMEWHAT STEEP MID LEVEL LAPSE
RATES... AND IF IT SETS UP FARTHER SOUTH (COVERING NE NC) AS THE
ECMWF INDICATES... WE WOULD HAVE A BETTER CHANCE OF SEEING BETTER
INSTABILITY AND A FEW SHOWERS OVER THE NE CWA WED. WILL RETAIN JUST
A SLIGHT CHANCE OVER THE FAR NE CWA FOR THE TIME BEING. BY THU A
WEAK BUT FAIRLY AMPLIFIED FULL-LATITUDE TROUGH PUSHING THROUGH THE
FRONT RANGE INTO THE PLAINS TRIES TO NUDGE THE MIDATLANTIC LOW
EASTWARD WITH LITTLE SUCCESS... KEEPING NC UNDER THE INFLUENCE OF
NNW MID LEVEL FLOW... WITH POCKETS OF VORTICITY ROTATING AROUND THE
LOW`S CENTER... AND A CYCLONIC NW/N SURFACE FLOW AS SURFACE HIGH
PRESSURE STARTS TO BUILD IN FROM THE NW. EXPECT DRY WEATHER THU WITH
A FEW CONVECTIVE CLOUDS IN THE AFTERNOON. MODEL SOLUTIONS START TO
DIVERGE REGARDING HOW MUCH CANADIAN ENERGY DROPS INTO THE VORTEX
JUST TO OUR NORTHEAST... BUT REGARDLESS IT LOOKS LIKE THIS LOW WILL
DRIFT TO THE NNE AWAY FROM NC AS A PORTION OF THE WEAK PLAINS TROUGH
DROPS SOUTHWARD TOWARD TX... YIELDING A BAGGING POSITIVELY TILTED
TROUGH AXIS THROUGH NC AND A LIGHT NW FLOW OVER NC. WITH HIGH
PRESSURE CENTERED TO OUR NW OR WEST EXTENDING OVER NC... EXPECT FAIR
SKIES AND DRY WEATHER. SEE NO REASON FOR THICKNESSES TO DEVIATE MUCH
FROM NORMAL VALUES... SO AFTER COOL CONDITIONS WED... WILL TREND
TEMPS UP TO WITHIN A FEW DEGREES OF NORMAL... LOWS IN THE MID-UPPER
40S AND HIGHS MAINLY IN THE UPPER 60S TO LOWER 70S. -GIH

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 745 PM SATURDAY...

24 HOUR TAF PERIOD: VERY HIGH CONFIDENCE OF VFR CONDITIONS THROUGH
THE TAF PERIOD. BREEZY GUSTS UP TO 20 KTS WILL BE SUBSIDING OVER THE
NEXT COUPLE OF HOURS AND WINDS WILL SETTLE INTO A SUSTAINED 5-10 KTS
OVERNIGHT OUT OF THE NORTHWEST. LINGERING SCATTERED TO BROKEN
CEILINGS AT 5-10 KFT SHOULD LIFT OUT AND EVENTUALLY CLEAR OUT
OVERNIGHT. FOR SUNDAY...THERE WILL BE A FEW HOURS AFTER SUNRISE
WHERE SOME GUSTS TO PLUS OR MINUS 15 KTS WILL BE POSSIBLE BEFORE
SURFACE HIGH PRESSURE MOVES MORE DIRECTLY OVERHEAD...CALMING THE
GUSTS AND WEAKENING THE SUSTAINED WINDS TO 5 KTS OR LESS ON SUNDAY
AFTERNOON. SKIES SHOULD REMAIN MOSTLY CLEAR THROUGH THE TAF PERIOD.

LONG TERM: THE NEXT CHANCE FOR ADVERSE AVIATION CONDITIONS COULD
COME WITH A STRONG UPPER LEVEL LOW THAT WILL MOVE NORTH OF THE AREA
TUESDAY NIGHT INTO WEDNESDAY. OTHERWISE...VFR CONDITIONS EXPECTED
THROUGH THE LONG TERM.

&&

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

&&

$$

SYNOPSIS...WSS
NEAR TERM...WSS
SHORT TERM...WSS
LONG TERM...HARTFIELD
AVIATION...ELLIS


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.