Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 261117
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
717 AM EDT TUE AUG 26 2014

.SYNOPSIS...HIGH PRESSURE WILL EXTEND SOUTHWARD INTO THE REGION
THROUGH WEDNESDAY. A WEAK BACK DOOR FRONT WILL APPROACH FROM THE
NORTH EARLY THURSDAY.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 250 AM TUESDAY...

TODAY AND TONIGHT: SURFACE HIGH PRESSURE CENTERED JUST TO THE NORTH
OF CENTRAL NC CONTINUES TO EXTEND SOUTHWARD INTO THE AREA THIS
MORNING... WHILE THE MID LEVEL RIGE AXIS IS CONTINUING TO SLOWLY
SINK SOUTHWARD AND EVENTUALLY ACROSS CENTRAL NC LATER TODAY. THIS
WILL LEAD TO ANOTHER DRY DAY ACROSS THE REGION. THE LATEST NAM AND
GFS CONTINUE TO SHOW A LITTLE BIT DRIER AIR WORKING INTO THE AREA
TODAY IN THE 925-850 MB LAYER. CURRENTLY IR SATELLITE IMAGERY SHOWS
A SHRINKING AREA OF CLOUD COVER TRAPPED BELOW THE PROMINENT
SUBSIDENCE INVERSION AT AROUND 850 MB. THE AREA OF CLOUD COVER IS
EXPECTED TO GENERALLY DISSIPATE OVER THE NEXT SEVERAL HOURS. STILL
THINK WE WILL SEE AT LEAST SOME STRATOCUMULUS DEVELOP THIS MORNING
IN THE MID MORNING/EARLY AFTERNOON TIME FRAME.... ALTHOUGH NOT AS
MUCH AS YESTERDAY. THUS... WOULD NOT EXPECT THE CLOUD COVER TO HAVE
AS BIG OF IMPACT ON HIGH TEMPS TODAY. GIVEN THE EXPECTED INCREASE IN
AFTERNOON LOW LEVEL THICKNESS VALUES OF AROUND 5-10 METERS... WOULD
EXPECT HIGH TEMPS WILL BE 2-5 DEGREES WARMER TODAY. THIS YIELDS
TEMPS GENERALLY IN THE MID 80S ACROSS THE AREA FOR TODAY.

OUTSIDE OF POSSIBLY SOME LINGERING MOISTURE/CLOUDS TRAPPED UNDER THE
SUBSIDENCE INVERSION AGAIN EARLY TONIGHT (LESS THAN THIS PAST
EVENING/CURRENTLY)... THINK SKIES SHOULD BECOME MOSTLY
CLEAR/CLEAR... WITH A LIGHT NORTHERLY BREEZE. WITH DEWPOINTS AGAIN
EXPECTED TO FALL INTO THE 50S AND LOW 60S OVERNIGHT.... THINK LOW
TEMPS WILL GENERALLY BE IN THE UPPER 50S TO LOWER 60S.

WEDNESDAY: HURRICANE CRISTOBAL IS EXPECTED TO LIFT NORTHWARD AND
PASS AROUND 500 MILES TO THE EAST OF THE NC COAST ON WEDNESDAY.
THUS... EXPECT NO IMPACT FROM THE PASSING TROPICAL SYSTEM FOR
CENTRAL NC... EXCEPT A POSSIBLE ENHANCED OF THE TEMPS ON THE WARM
SIDE OVER OUR AREA. AFTERNOON LOW LEVEL THICKNESS VALUES ARE
EXPECTED TO INCREASE SOME 15 TO 25 METERS ON WEDNESDAY... VS TODAY.
THUS... HAVE RAISED HIGH TEMPS ON WEDNESDAY TO AROUND 90/LOWER
90S... AND WE COULD EVEN SEE A FEW MID 90S. OTHERWISE DRY WEATHER IS
EXPECTED AS VERY STABLE CONDITIONS PERSIST OVER THE AREA.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 330 AM TUESDAY...

A S/W CROSSING THE EASTERN LAKES/NEW ENGLAND WEDNESDAY NIGHT-
THURSDAY WILL SEND A BACKDOOR COLD FRONT TOWARD CENTRAL
NC...POSSIBLY DRIFTING INTO THE FAR NORTH-NE COUNTIES BY THURSDAY
AFTERNOON. MEANWHILE A WEAK VORT MAX PROJECTED TO CROSS
NORTHERN/CENTRAL VA LATE THU-THU NIGHT. MODEL GUIDANCE SUGGESTING
THAT ENOUGH MOISTURE WILL POOL IN THE VICINITY OF THIS FEATURE ALONG
WITH AVAILABLE INSTABILITY TO TRIGGER ISOLATED THUNDERSTORMS LATE
THU-THU NIGHT NEAR THE VIRGINIA BORDER. OTHERWISE ATMOSPHERE ACROSS
THE REMAINDER OF CENTRAL NC APPEARS TOO DRY AND TOO WARM IN THE MID
LEVELS TO SUPPORT THE DEVELOPMENT OF ISOLATED CONVECTION.
HOWEVER...IF MID LEVEL CAP WEAKER THAN PROJECTED...WOULD NOT BE
SURPRISED TO SEE A STORM OR TWO MAKE A RUN AS FAR SOUTH AS HIGHWAY
64 THURSDAY EVENING. THICKNESSES THURSDAY AFTERNOON AVERAGE 12-15M
ABOVE NORMAL FOR LATE AUGUST. THIS SUPPORTS MAX TEMPS IN THE 90-95
DEGREE RANGE. MIN TEMPS WEDNESDAY NIGHT WILL AVERAGE IN THE MID-
UPPER 60S...AND THE UPPER 60S-AROUND 70 THURSDAY NIGHT.

FRIDAY...SURFACE BOUNDARY BECOMES DIFFUSE WHILE MID-UPPER LEVEL
HEIGHTS INCREASE ACROSS THE REGION. THIS SUGGEST A WARM AND DRY
FORECAST FOR THE START OF THE HOLIDAY WEEKEND. STILL CANNOT RULE OUT
THE POSSIBILITY OF AN ISOLATED STORM LATE FRIDAY/FRIDAY EVENING IN
VICINITY OF THE OLD SURFACE BOUNDARY.  MAX TEMPS RANGE FROM THE
UPPER 80S ACROSS THE FAR NORTH WHERE PERIODS OF CLOUDINESS MAY
OCCUR...TO THE LOWER 90S SOUTH.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... AS OF 330 AM TUESDAY...

SATURDAY THROUGH MONDAY... WEATHER PATTERN WILL BECOME INCREASINGLY
UNSETTLED DURING THE REST OF THE HOLIDAY WEEKEND. MID-UPPER LEVEL
RIDGE OVER THE REGION WILL WEAKEN IN RESPONSE TO A SERIES OF S/W
LIFTING NE ACROSS THE OH VALLEY/GREAT LAKES/NORTHERN MID ATLANTIC.
ANY CONVECTION SATURDAY APPEARS TO BE DIURNALLY DRIVEN AND SHOULD
REMAIN NO WORSE THAN ISOLATED. BY SUNDAY...MODEST HEIGHT FALLS PLUS
AN INCREASE IN AVAILABLE MOISTURE WILL ENHANCE THE LIKELIHOOD OF
SCATTERED CONVECTION SUNDAY AFTERNOON AND EVENING. LABOR DAY WILL
LIKELY SEE THE BETTER CHANCES FOR CONVECTION WITH THE LOW-MID LEVEL
FLOW TAPPING MOISTURE OFF THE ATLANTIC AS WELL AS THE NORTHERN GULF.

MAX TEMPS WILL GRADUALLY "COOL" AS CLOUD COVER INCREASES. IN
ADDITION...WILL SEE A RETURN OF HUMID/MUGGY CONDITIONS...MORE
TYPICAL OF LATE SUMMER. MAX TEMPS SATURDAY NEAR 90-LOWER 90S DROP TO
THE MID 80S-UPPER 80S BY MONDAY.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 715 AM TUESDAY...

24-HR TAF PERIOD: VFR CONDITIONS ARE EXPECTED TO CONTINUE ALONG WITH
A NORTH TO NORTHEASTERLY BREEZE THROUGH THE TAF PERIOD AS DRY HIGH
PRESSURE EXTENDS SOUTHWARD INTO THE CAROLINAS.

GIVEN A BIT LESS IN THE WAY OF LOW LEVEL MOISTURE IS EXPECTED
TODAY... DO NOT EXPECT AS MUCH IN THE WAY OF CLOUD COVER TO DEVELOP
WITH SURFACE HEATING THIS MORNING/AFTERNOON. WE COULD SEE SOME
SCATTERED CLOUDS DEVELOP IN THE 2-3.5 KFT RANGE DURING THE MID
MORNING... BUT CONFIDENCE IN ANY SUB-VFR BROKEN/OVERCAST CLOUD COVER
IS TOO LOW TO INCLUDE ANY MENTION IN THE TAFS AT THIS TIME. NORTH-
NORTHEASTERLY WINDS RANGING FROM 6-8 KTS AT KGSO/KINT TO 9-12 KTS
ELSEWHERE ARE EXCEPTED TODAY. WINDS WILL GENERALLY BECOME LIGHT AND
VARIABLE AFTER SUNSET THIS EVENING. CANNOT COMPLETELY RULE OUT SOME
PATCHY SUB-VFR VISBYS WEDNESDAY MORNING... AS WE SHOULD HAVE GOOD
RADIATIONAL COOLING CONDITIONS. KRWI... WILL HAVE THE BEST CHANCE OF
SEEING SOME SUB-VFR VISBYS.

LOOKING AHEAD: VFR CONDITIONS WILL PREVAIL THROUGH MID-WEEK AS DRY
HIGH PRESSURE PERSISTS OVER THE CAROLINAS. A SMALL CHANCE FOR ISOLD
CONVECTION WILL RETURN THU/FRI AS A WEAK BACKDOOR FRONT DRIFTS INTO
THE REGION FROM THE NORTH...THOUGH VFR CONDITIONS SHOULD STILL
PREVAIL AT MOST (IF NOT ALL) TERMINALS.

&&

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

&&

$$

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


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