-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 281139
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
639 AM EST WED JAN 28 2015

.SYNOPSIS...HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH EARLY
THURSDAY... BEFORE PUSHING TO OUR SOUTH. A CLIPPER LOW PRESSURE
SYSTEM AND ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE AREA LATE
THURSDAY AND THURSDAY NIGHT. COOL HIGH PRESSURE WILL BUILD BACK IN
FROM THE WEST FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 244 AM WEDNESDAY...

VERY STRONG LOW PRESSURE SYSTEM OFF OF THE NEW ENGLAND COAST WILL
CONTINUE TO GRADUALLY SLIDE NORTHEASTWARD TODAY. IN ITS WAKE SURFACE
HIGH PRESSURE WILL BUILD IN FROM THE OHIO VALLEY WITH AN UPPER LEVEL
RIGE CENTERED OVER THE MIDWEST. THIS WILL KEEP FLOW AT THE SURFACE
NORTHERLY AND AS A RESULT TEMPERATURES WILL BE BELOW NORMAL TODAY
WITH HIGHS IN THE MID 40S. DESPITE THE COLD THERE WILL BE PLENTY OF
SUNSHINE AS SKIES REMAIN CLEAR. WEATHER IS EXPECTED TO REMAIN
SETTLED AS THE PARADE OF SHORTWAVES ON THE BACK SIDE OF THE EXITING
LOW PRESSURE SYSTEM CEASES. MAYBE A FEW WIND GUSTS TO 15-20 KTS IN
THE EAST THIS MORNING AS BUT OTHERWISE QUIET WEATHER IS EXPECTED.
WINDS WILL CALM LATER ON TONIGHT INTO THURSDAY MORNING BUT UPPER
LEVEL CLOUDS WILL ENCROACH ON NORTHERN AREAS OVERNIGHT WEDNESDAY
NIGHT...ESPECIALLY ACROSS THE NORTH...HAMPERING OPTIMAL RADIATIONAL
COOLING. THICKNESS VALUES ALSO WILL BE HIGHER IN THE WEST THAN IN
THE EAST...THEREFORE BETWEEN THE CLOUDS AND THE THICKNESS
VALUES..EXPECT THE LOWEST TEMPERATURES OVERNIGHT IN OUR SOUTHERN AND
EASTERN RURAL AREAS. LOWS IN THE LOW TO MID 20S.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 245 AM WEDNESDAY...

HIGH PRESSURE WILL REMAIN IN CONTROL ON THURSDAY FOR MUCH OF THE DAY
AS IT MOVE ACROSS EASTERN NC AND EVENTUALLY OUT INTO THE WESTERN
ATLANTIC. THIS WILL PUT CENTRAL NC ON THE WARM SIDE OF THE HIGH IN
THE SOUTHERLY RETURN FLOW WHICH WILL HELP TEMPERATURES RECOVER BUT
ONLY LIMITED AS HIGH AND MID-LEVEL CLOUDS WILL OVERSPREAD THE AREA
DURING PEAK HEATING AND LIMIT THE AMOUNT OF INSOLATION. THEREFORE WE
WILL HAVE TO SETTLE FOR UPPER 40S NORTH TO LOWER 50S SOUTH. BY
THURSDAY EVENING A LOW PRESSURE SYSTEM WILL BE CENTERED OVER THE
GREAT LAKES WITH A COLD FRONT EXTENDING DOWN THE APPALACHIANS. IN
OUR AREA...MOISTURE WILL BE VERY LIMITED AND THEREFORE PRECIPITATION
IS A LOW CONFIDENCE FORECAST AT THE MOMENT. PRECIPITABLE WATER
VALUES ONLY RISE TO A HALF OF AN INCH OF WATER AND ALL MODELS HINT
AT PRECIPITATION FIZZLING OUT OVER CENTRAL NC AND THEN PICKING UP
AGAIN OFFSHORE. FORCING WITH THIS SYSTEM IS MOSTLY IN THE UPPER
LEVELS WITH THE LEFT EXIT REGION OF A 120 KT 500 MB JET STREAM
MOVING ACROSS THE CWA FROM WEST TO EAST CREATING A 500 MB VORT MAX
THAT WILL PROVIDE SUBSTANTIAL UPPER LEVEL LIFT FOR A PERIOD OF TIME
BETWEEN 00Z AND 06Z FRIDAY MORNING BUT WHETHER OR NOT ENOUGH
MOISTURE REMAINS TO PRODUCE SHOWERS THAT ARE ABLE TO OVERCOME LOW
LEVEL DRY AIR REMAINS TO BE SEEN. WILL CARRY A SLIGHT CHANCE THROUGH
THAT 0-6Z TIMEFRAME BUT OTHERWISE WILL KEEP THE FORECAST DRY. LOWS
THURSDAY NIGHT IN THE LOW 30S NW TO UPPER 30S SE.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 225 AM WEDNESDAY...

FRI-SAT NIGHT: DRY AND COOL. LATEST MODEL RUNS UNANIMOUSLY SHOW THE
SURFACE FRONT OFF THE NC COAST FRI MORNING WITH COLD AIR ADVECTION
COMMENCING... AS SURFACE HIGH PRESSURE INITIALLY CENTERED OVER THE
UPPER MIDWEST PUSHES EASTWARD WHILE BUILDING SOUTH INTO NC. GOOD
MIXING AND A TIGHT MSLP GRADIENT WILL BRING BRISK NORTHWEST WINDS
SUSTAINED UP TO 15-20 MPH... AND MOMENTUM TRANSFER SUPPORTS GUSTS TO
25-30 MPH FROM LATE MORNING THROUGH THE AFTERNOON... ABATING SLOWLY
IN THE EVENING WITH THE GRADUAL LOSS OF MIXING. FALLING THICKNESSES
FRI INDICATE HIGHS IN THE MID 40S TO AROUND 50 DESPITE PLENTY OF
SUNSHINE. WINDS FALL OFF FRI NIGHT BUT DON`T GO COMPLETELY CALM...
YET THE CHILLY AIR MASS BUILDING IN WITH CLEAR SKIES AND OTHERWISE
DECENT RADIATIONAL COOLING STILL FAVORS LOWS IN THE LOW-MID 20S...
AND WOULD NOT BE SURPRISED TO SEE A FEW TEENS IN OUTLYING AREAS.
SUNSHINE CONTINUES SAT AS THE HIGH RIDGES SOUTHWARD INTO NC. HIGHS
STILL BELOW NORMAL... 44-48. THE MID LEVEL RIDGE AXIS SHIFTS OVER
AND JUST EAST OF THE CAROLINAS SAT NIGHT AS THE SURFACE RIDGE MOVES
SSE AND OFFSHORE... AND WE SHOULD SEE INCREASING HIGH CLOUDS LATE AS
WSW MID LEVEL FLOW STARTS DRAWING IN WEAK SOUTHERN STREAM VORTICITY
FROM THE BAJA LOW. LOWS IN THE UPPER 20S TO AROUND 30.

SUN-TUE: CONFIDENCE INCREASING THAT WE`LL SEE A GOOD SHOT OF RAIN...
LIKELY FOCUSED IN THE SUN NIGHT-MON TIME FRAME. THE ECWMF IS A BIT
FASTER THAN THE GFS BY ABOUT 3-6 HRS... AND WILL GO WITH A
COMPROMISE TIMING SOLUTION FOR NOW... BUT OTHERWISE THE TWO MODELS
ARE IN GOOD AGREEMENT ON AMPLIFICATION AND PRECIP PLACEMENT. A
POTENT NORTHERN STREAM SHORTWAVE TROUGH TRACKS THROUGH THE CENTRAL
MISS VALLEY SUNDAY/SUN NIGHT AS ITS ASSOCIATED PRIMARY SURFACE LOW
MOVES JUST AHEAD OF IT THROUGH THE OH VALLEY... ALL THE WHILE
PULLING INCREASING SOUTHERN-STREAM MOISTURE FROM EAST OF THE NW-
MEXICO LOW... ALONG AND AHEAD OF THE TRAILING SURFACE COLD FRONT
INTO THE GULF STATES AND MID SOUTH. THE ECMWF/GFS COMPROMISE TIMING
SUPPORTS BRINGING A CHANCE OF RAIN INTO THE FAR WRN CWA LATE SUN...
FOLLOWED BY WIDESPREAD RAIN SPREADING EASTWARD SUN EVENING THROUGH
THE FIRST HALF OF MONDAY... AS THE NORTHERN STREAM SHORTWAVE TROUGH
CROSSES THE OH VALLEY/CENTRAL APPALACHIANS INTO THE NORTHEAST/MID
ATLANTIC REGION. HAVE SLOWED DOWN BOTH THE ARRIVAL AND EXIT OF
PRECIP BY A FEW HOURS... AND HAVE RAISED POPS A BIT MORE AT THE
EVENT`S PEAK BASED ON GOOD AGREEMENT AMONG THE MODELS AND THEIR
ENSEMBLE MEMBERS... AND VERY HIGH VALUES OF LOW LEVEL MOISTURE FLUX
AND VIGOROUS DYNAMIC FORCING FOR ASCENT. LOW LEVEL THICKNESSES SOAR
OVER CENTRAL NC SUNDAY THROUGH AT LEAST THE FIRST HALF OF MON...
ALTHOUGH THERE IS STILL A CHANCE OF A LINGERING COOL STABLE POOL
OVER THE NW PIEDMONT. SO WE SHOULD SEE ABOVE NORMAL TEMPS... MAINLY
OVER THE SRN AND ERN CWA... DESPITE THE HIGH CHANCE OF SHOWERS. THE
GFS DEPICTS A COUPLE HUNDRED J/KG OF MUCAPE AHEAD OF THE FRONT...
AND IF THIS WEAK INSTABILITY PERSISTS IN LATER RUNS... A RISK OF
THUNDER MAY NEED TO BE ADDED. FRONTAL PASSAGE IS MOST LIKELY MON
AFTERNOON... WITH PLUNGING THICKNESSES POST-FRONT AS ANOTHER
CANADIAN SOURCE HIGH BUILDS IN FROM THE NW. EXPECT CLEARING SKIES
MON EVENING WITH TEMPS RETURNING TO BELOW NORMAL VALUES MON NIGHT
THROUGH TUE. -GIH

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 640 AM WEDNESDAY...

24 HOUR TAF PERIOD: VERY HIGH CONFIDENCE OF VFR CONDITIONS THROUGH
THE TAF PERIOD. LIGHT NORTHERLY WINDS THIS MORNING WILL GO TO CALM
LATER THIS EVENING. MOSTLY CLEAR SKIES TODAY WITH SOME HIGH CLOUDS
POSSIBLY CREEPING IN AT THE END OF THE TAF PERIOD.

LONG TERM: THE NEXT THREAT TO AVIATION CONDITIONS WILL BE THURSDAY
NIGHT INTO FRIDAY MORNING AS A FRONTAL SYSTEM CROSSES THE AREA AND
THEN ANOTHER SYSTEM SUNDAY NIGHT THROUGH MONDAY. FORECAST CONFIDENCE
IN THE THURSDAY EVENT IS LOWER THAN NORMAL AND CONDITIONS COULD
REMAIN VFR THROUGH THE EVENT. THERE IS HIGHER CONFIDENCE IN THE
SUNDAY EVENT BRINGING SOME ADVERSE AVIATION CONDITIONS.
-- End Changed Discussion --


&&

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

&&

$$

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