Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 261925
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
325 PM EDT SUN APR 26 2015

.SYNOPSIS...A WEAK AREA OF HIGH PRESSURE WILL BUILD INTO CENTRAL NC
TONIGHT AND MONDAY...AND SETTLE OVERHEAD MONDAY NIGHT INTO TUESDAY.
AN AREA OF LOW PRESSURE WILL BEGIN TO AFFECT OUR REGION TUESDAY NIGHT
AND WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 245 PM SUNDAY...

MAIN FORECAST CHALLENGE IN THE NEAR TERM CENTERS ON WHEN SKIES ARE
EXPECTED TO CLEAR. VISIBLE IMAGERY DOES SHOW A SOUTHWARD DRIFT TO
THE CLEARING-OUT OF THE LOW CLOUDS OVER CENTRAL-SOUTHEAST VA EARLY
THIS AFTERNOON. THIS SURGE OF DRIER AIR IS OCCURRING IN THE WAKE OF
THE PASSAGE OF THE 850MB TROUGH. THIS FEATURE CURRENTLY DRIFTING
SOUTH OVER CENTRAL NC (IN VICINITY OF HIGHWAY 64). MODEL GUIDANCE
SUGGEST LOW CLOUDS DEPARTING NORTH-SOUTH BETWEEN 21Z-02Z. WILL LEAN
FORECAST IN THIS DIRECTION. HOWEVER...POTENTIAL FOR THE
OVERCAST/BROKEN SKIES TO PERSIST A BIT LONGER THAN FORECAST AS LOSS
OF INSOLATION MAY SLOW CLOUD EROSION PROCESS.

OTHERWISE MAY SEE A FEW PATCHES OF RAIN WITH THE PASSAGE OF THE
850MB TROUGH OVER THE SOUTHERN COUNTIES LATE THIS AFTERNOON-EARLY
EVENING. COVERAGE EXPECTED TO BE ISOLATED AND OBSERVED AMOUNTS WILL
TOTAL NO MORE THAN A TRACE OR A HUNDREDTH.

A LIGHT NLY WIND THIS EVENING WILL SUBSIDE TO NEAR CALM OVERNIGHT.
IF PARTIAL CLEARING OCCURS...POTENTIAL FOR POCKETS OF FOG TO
DEVELOP. MIN TEMPS LOW-MID 40S.

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
AS OF 245 PM SUNDAY...

MONDAY...A MINOR S/W WILL CROSS THE NORTHERN MID ATLANTIC
MONDAY...BRUSHING NE NC IN THE LATE AFTERNOON. THIS FEATURE WILL
LIKELY ENHANCE STRATOCU COVERAGE OVER THE NORTHERN COASTAL PLAIN
WITH AN ISOLATED PATCH OF LIGHT RAIN POSSIBLE. ELSEWHERE THE SUN
WILL MAKE AN APPEARANCE. A STEADY NW LOW LEVEL FLOW WILL AID TO
DIMINISH ANY LINGERING LOW CLOUD COVER OVER THE REST OF THE PIEDMONT
AND SANDHILLS. TEMPERATURES WILL RECOVER NICELY IN THIS DOWNSLOPE
WIND REGIME. AFTERNOON TEMPS WILL VARY FROM THE MID-UPPER 60S IN THE
PIEDMONT/NORTHERN COASTAL PLAIN TO AROUND 70 IN THE SE.

MONDAY NIGHT...NOSE OF SFC RIDGE WILL EXTEND ACROSS THE REGION. DRY
AIR UNDERNEATH THIS RIDGE WILL RESULT IN MOSTLY CLEAR SKIES. MIN
TEMPS WILL BE CHILLY..DIPPING INTO THE UPPER 30S AND LOWER 40S. AT
THIS TIME...NOT EXPECTING TEMPS TO DIP BELOW 37 DEGREES. THUS PATCHY
LIGHT FROST NOT A CONCERN...BUT WILL CONTINUE TO MONITOR.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
AS OF 320 PM SUNDAY...

TUESDAY AND TUESDAY NIGHT: BRIEF S/W RIDGING WILL BUILD OVER THE
AREA ON TUESDAY... WITH A SURFACE RIDGE AXIS INITIALLY EXTENDING
INTO THE AREA FROM THE NORTHWEST (BEFORE A PIECE OF THE HIGH BREAKS
OFF OVER THE CAROLINAS). THIS SHOULD ALLOW FOR MOSTLY SUNNY TO
PARTLY SUNNY SKIES... WITH LOW LEVEL THICKNESS VALUES STILL RUNNING
AT LEAST SOME 20-25 METERS BELOW NORMAL. GIVEN THIS EXPECT WE SHOULD
SEE HIGH TEMPS GENERALLY IN THE 60S... WITH PERHAPS A FEW LOCATIONS
TOUCHING 70 ACROSS THE SOUTH/SOUTHEAST.

CLOUD COVER WILL QUICKLY THICKEN ON TUESDAY NIGHT/EARLY WEDNESDAY
MORNING IN ADVANCE OF A SOUTHERN STREAM SYSTEM... WITH POSSIBLY SOME
RAIN SPREADING INTO THE SOUTHWESTERN/WESTERN PORTIONS OF THE AREA
NEAR DAYBREAK WEDNESDAY PER THE GFS AND ECMWF. THE LATEST NAM
(12Z/26TH) HAS PRECIP SPREADING INTO SOUTHERN PORTIONS OF THE AREA
BY MID TO LATE TUESDAY EVENING EVEN. GIVEN THIS SEEMS TO BE A FAST
OUTLIER WILL CONTINUE TO TREND TOWARDS A BLEND OF THE GFS/ECMWF FOR
THIS PERIOD OF THE FORECAST. WRT LOW TEMPS... WILL SHOW A RANGE FROM
THE MID 40S NE (WHERE WE WILL HAVE THE BEST NOCTURNAL COOLING) TO
AROUND 50 SW. HOWEVER... WITH A DRIER SURFACE AIRMASS IN PLACE WE
SHOULD SEE TEMPS BEGIN TO WETBULB WITH THE ARRIVAL OF THE PRECIP.
THUS... TEMPS MAY FALL AFTER SUNSET SOME IN THE SW FROM THE LOSS OF
DAYTIME HEATING... THEN STABILIZE BY MID TO LATE EVENING WITH THE
INCREASING/THICKENING CLOUD COVER... BEFORE ONCE AGAIN FALLING WITH
AS THE RAIN ARRIVES. THUS... LOW TEMPS ARE TRICKY FOR WEDNESDAY
MORNING AND WILL BE DEPENDENT ON THE TIMING AND INTENSITY OF THE
RAIN FOR LOCATIONS THAT DO INDEED SEE PRECIP MOVE INTO THE AREA
DURING THE EARLY MORNING HOURS OF WEDNESDAY.

WEDNESDAY THROUGH FRIDAY NIGHT: MEDIUM RANGE MODELS ARE IN BETTER
AGREEMENT TODAY IN SHOWING A SOUTHERN STREAM MID LEVEL LOW OVER
NORTHERN TX TO BEGIN THE WEEK TRANSLATING EASTWARD AND SPAWNING A
SURFACE LOW NEAR THE GULF COAST... THEN TRACKING TOWARDS OUR REGION
TUESDAY NIGHT INTO WEDNESDAY... WITH THE EXPECTED SURFACE LOW
TRACKING EASTWARD-NORTHEASTWARD AND EVENTUALLY NORTHEASTWARD ALONG
OUR COAST BY THURSDAY MORNING. GIVEN THE RATHER DRY AIRMASS
PRECEDING THIS SYSTEM... EXPECT WE SHOULD SEE A CAD AIRMASS DEVELOP
ACROSS CENTRAL NC ON WEDNESDAY AS RAIN OVERSPREADS THE REGION FROM
SOUTHWEST TO NORTHEAST (POSSIBLY BEGINNING DURING THE EARLY MORNING
HOURS OF WEDNESDAY (AGAIN... WE STAYED CLOSE TO GFS/ECMWF FOR
TIMING). THE CAD AIRMASS IS EXPECTED TO LINGER ACROSS PORTIONS OF
CENTRAL NC ON THURSDAY (WITH BELOW NORMAL TEMPS EVEN EXPECTED FOR
LOCATIONS THAT EVEN SEE SOME BREAKS IN THE CLOUDS STILL)... BEFORE
SLOWLY ERODING ON THURSDAY NIGHT INTO FRIDAY AS THE SURFACE LOW
LIFTS OFF TO THE NORTHEAST... YIELDING MORE OF A NORTH TO
NORTHWESTERLY LOW TO MID LEVEL FLOW. CHANCES FOR RAIN SHOULD BEGIN
TO DECREASE BY LATE THURSDAY INTO THURSDAY EVENING... WITH GENERALLY
DRY WEATHER AGAIN EXPECTED BY FRIDAY.

HIGH TEMPS ON WEDNESDAY ARE EXPECTED TO BE WELL BELOW NORMAL WITH
THE EXPECTED CAD DEVELOPMENT. FOR NOW HAVE LOWERED HIGHS INTO THE
MID TO UPPER 50S NW TO THE MID 60S FAR NE FOR WEDNESDAY. HIGHS
THURSDAY AND FRIDAY IN THE 60S TO NEAR 70 ON FRIDAY IN THE SOUTH...
STILL BELOW NORMAL. LOWS ARE EXPECTED TO BE IN THE UPPER 40S TO
LOWER 50S FOR THE PERIOD.

SATURDAY THROUGH SUNDAY: MID LEVEL HEIGHTS ARE EXPECTED TO RISE NEXT
WEEKEND. THIS COUPLED WITH HIGH PRESSURE AT THE SURFACE WILL ALLOW
FOR A WARMING A DRYING TREND IN CENTRAL NC. THIS SHOULD RESULT IN
HIGHS IN THE 70S AND LOWS IN THE 50S... NEAR NORMAL FOR THIS TIME OF
YEAR... WITH POSSIBLY EVEN ABOVE NORMAL HIGHS FOR SUNDAY AFTERNOON
(MAYBE SOME LOW 80S).

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 125 PM SUNDAY...

HIGH LIKELIHOOD THAT MVFR CONDITIONS WILL PERSIST THROUGH 21Z ACROSS
CENTRAL NC. AFTER 21Z...NLY FLOW WILL BEGIN TO INFILTRATE A DRIER
AIR MASS INTO THE LOWEST 5K FEET OF THE ATMOSPHERE WHICH SHOULD AID
TO DIMINISH THE LOW STRATUS. THIS SHOULD LEAD TO VFR CONDITIONS
ACROSS CENTRAL NC THIS EVENING. AFTER 03Z...WILL LIKELY SEE POCKETS
OF IFR/LIFR FOG DEVELOP WHICH MAY AFFECT MOST IF NOT ALL TERMINALS
AFTER 06Z. THE PATCHY OR AREAS OF FOG SHOULD LIFT/DISSIPATE BY 12Z.

VFR CONDITIONS ANTICIPATED MONDAY INTO TUESDAY AS AN AREA OF HIGH
PRESSURE WILL DOMINATE OUR WEATHER PATTERN. ASIDE FROM A BRIEF
PERIOD OF MVFR FOG TUESDAY MORNING...VFR CONDITIONS SHOULD RULE.

AN APPROACHING LOW PRESSURE SYSTEM WILL BRING A CHANCE OF SUB VFR
CONDITIONS TO CENTRAL NC WEDNESDAY INTO THURSDAY. IMPROVING AVIATION
CONDITIONS ARE ANTICIPATED THURSDAY NIGHT INTO FRIDAY.

&&


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

&&

$$

SYNOPSIS...WSS
NEAR TERM...WSS
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...WSS


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