Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 181747
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
145 PM EDT THU SEP 18 2014

.SYNOPSIS...HIGH PRESSURE CENTERED OVER THE NORTHERN GREAT LAKES
WILL EXTEND DOWN THROUGH VIRGINIA AND THE CAROLINAS THROUGH THE
WEEKEND... AS IT SLIDES EAST. A COLD FRONT WILL APPROACH FROM THE
NORTHWEST LATE SUNDAY... THEN MOVE SOUTHEAST THROUGH THE REGION
MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1035 AM THURSDAY...

REST OF TODAY: STILL APPEARS MOSTLY DRY WITH SEASONABLE TEMPS. THIS
MORNING`S AREAS OF LOW CLOUDS HAVE MIXED OUT OVER ALL BUT THE FAR
WRN CWA... WHERE THE LOW LEVEL TERRAIN UPGLIDE IS HIGHER AND WHERE
LOW LEVEL MASS CONVERGENCE IS TAKING PLACE ALONG A WEAK INVERTED
SURFACE TROUGH. THE LATEST CONVECTION-ALLOWING MODELS GENERALLY
AGREE ON ISOLATED SHALLOW SHOWERS FORMING OVER THE MOUNTAINS AND
FOOTHILLS EARLY-MID AFTERNOON... AND SUBSEQUENTLY DRIFTING EASTWARD
INTO THE FAR WRN PIEDMONT THROUGH EVENING BEFORE DISSIPATING. THE
12Z GSO SOUNDING REVEALS PLENTIFUL MOISTURE BELOW 775 MB CAPPED BY
THE INVERSION ALOFT... SUFFICIENT TO SUPPORT A FEW SHOWERS. WILL
RETAIN ISOLATED SHOWERS FROM MID AFTERNOON THROUGH THIS EVENING IN
THE FAR WRN AND EXTREME SW CWA. OTHERWISE... THE WARM CAP ALOFT AND
DRY MID LEVELS ALONG WITH BELOW NORMAL PW WILL MAKE FOR DRY
CONDITIONS OVER THE REST OF THE CWA... WITH FLAT CUMULUS MAXIMIZED
IN THE AFTERNOON. THE PACE OF TEMP RISE SO FAR THIS MORNING
SUPPORTS HIGHS OF 77-81. -GIH

TONIGHT...AVAILABLE LOW LEVEL MOISTURE IN THE WESTERN PIEDMONT...
POOLING ALONG THE SFC TROUGH...MAY MAINTAIN A FEW SHOWERS THROUGH
THE LATE EVENING HOURS. OTHERWISE AVAILABLE LOW LEVEL MOISTURE MAY
CAUSE THE FORMATION OF FOG AND/OR LOW CLOUDS... ESPECIALLY OVER THE
PIEDMONT. MIN TEMPS NEAR 60-LOWER 60S. -WSS

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 310 AM THURSDAY...

DRY AIR RIDGE WILL BUILD INTO AND EXTEND
ACROSS CENTRAL NC THIS PERIOD. THE DRIEST AIR WILL ENCOMPASS THE NE
PIEDMONT AND MOST OF THE COASTAL PLAIN. THE LOW LEVEL EASTERLY FLOW
MAY CAUSE MOISTURE TO BANK UP AGAINST THE HIGHER TERRAIN OF WESTERN
NC WHICH MAY SPILL INTO OUR FAR WESTERN  COUNTIES. THE MOISTURE
APPEARS TOO SHALLOW TO SUPPORT ANY SHOWER ACTIVITY PLUS LIFT IS
MINIMAL THIS PERIOD.

MAX TEMPS SIMILAR TO TODAY IN THE UPPER 70S TO THE LOWER 80S. MIN
TEMPS FRIDAY NIGHT IN THE UPPER 50S TO THE LOWER 60S.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...

A PORTION OF THE LONGWAVE TROUGH INITIALLY ALONG THE EAST COAST WILL
BE LEFT BEHIND AND SUPPORT WEAK FRONTAL WAVE DEVELOPMENT OFFSHORE
THE SE US COAST THIS WEEKEND...BUT THE OTHERWISE DEAMPLIFYING/LIFTING
TROUGH WILL YIELD TO RISING HEIGHTS ALOFT OVER THE CAROLINAS...AS A
FLAT MID LEVEL RIDGE RIDGE NOSES EASTWARD FROM THE SOUTHERN PLAINS
AND LOWER MS VALLEY. THE RE-ESTABLISHMENT AND AMPLIFICATION OF A
WESTERN NOAM RIDGE WILL THEN RESULT IN DOWNSTREAM TROUGH
AMPLIFICATION FROM SOUTH-CENTRAL CANADA TO THE EAST-CENTRAL US THIS
WEEKEND-EARLY NEXT WEEK. THE WESTERN RIDGE...IN PROGRESSIVE FLOW
ALOFT...WILL BUILD EAST ACROSS THE MID-LATITUDES OF THE CENTRAL AND
EASTERN STATES MID TO LATE NEXT WEEK.

BENEATH THE CONTINUED RISING HEIGHTS ALOFT SAT...A CANADIAN SFC HIGH
(AROUND 1030 MB) WILL BUILD FROM CENTRAL CANADA TO THE CANADIAN
MARITIMES AND RIDGE SOUTH/SOUTHWESTWARD THROUGH THE EASTERN STATES
THROUGH THE FIRST HALF OF THE WEEKEND...BEFORE YIELDING - AMIDST
FALLING HEIGHTS DOWNSTREAM OF THE AFOREMENTIONED REDEVELOPING TROUGH
ALOFT HEADED FOR THE EAST-CENTRAL US - TO APPALACHIAN-LEE SFC TROUGH
DEVELOPMENT SUN...AND A PASSING COLD FRONT MON. ANOTHER STRONG
CANADIAN HIGH WILL EXPAND AND STRENGTHEN ACROSS MUCH OF THE CENTRAL
AND EASTERN CONUS IN THE WAKE OF THE PASSING COLD FRONT...WHICH
GUIDANCE SUGGESTS WILL CLEAR ALL BUT PERHAPS SOUTHERN FL BY MID NEXT
WEEK.

WITH THE BRUNT OF THE COOLER AND DRIER AIR ASSOCIATED WITH THE LEAD
HIGH LIKELY TO HOLD OVER THE NORTHERN MIDDLE ATLANTIC AND NORTHEAST
STATES THIS WEEKEND...CENTRAL NC TEMPERATURES ARE APT TO WARM TO ABOVE
AVG...IN THE LOWER TO MIDDLE 80S - WARMEST SUNDAY. ANY SIGNIFICANT
LOW-MID LEVEL CLOUD COVER ATTENDING THE OFFSHORE FRONTAL WAVE IS
FORECAST AT THIS TIME TO HOLD ALONG COASTAL AREAS...WITH MORE OF A
NORTHWESTERLY FLOW COMPONENT OVER CENTRAL NC...INTO THE OFFSHORE
LOW/FRONTAL ZONE.

FRONTAL PASSAGE TIMING HAS SPED FOR MON...SUCH THAT A FEW LINGERING
SHOWERS FROM UPSTREAM CONVECTION MAY DRIFT INTO THE NW PIEDMONT SUN
NIGHT...AND LEAVE MAINLY THE FAR SOUTHEAST CWFA IN THE WARM SECTOR
THROUGH EARLY AFTERNOON...WITH EARLIER/UNFAVORABLE DIURNAL FRONTAL
TIMING ACROSS THE REMAINDER OF THE AREA. SHOWER CHANCES WILL BE
RELATIVELY LOW...THROUGHOUT THIS PERIOD...HOWEVER...AS GULF MOISTURE
RETURN WILL BE LIMITED. COOLER TUE-WED...WITH HIGHS IN THE 70S IN
THE POST-FRONTAL CANADIAN HIGH...WITH SFC DEWPOINTS IN THE 40S-50S.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 145 PM THURSDAY...

VFR CONDITIONS ARE LIKELY TO HOLD THROUGH THE TAF FORECAST PERIOD.
EARLIER MVFR CIGS AT INT/GSO HAVE MIXED OUT TO SCATTERED... ALTHOUGH
THESE MAY STILL GO BROKEN BRIEFLY PRIOR TO 20Z. OTHERWISE... ANY
CLOUDS THROUGH TONIGHT AND FRI MORNING SHOULD BE BASED ABOVE 3 000
FT AGL... MORE LIKELY TO BE BROKEN AT INT/GSO WITH LESS COVERAGE AT
RDU/RWI/FAY. LIGHT AND VARIABLE WINDS MAINLY FROM THE NE WILL
CONTINUE TONIGHT AT SPEEDS MAINLY UNDER 6 KTS... THEN SHOULD
INCREASE TO 7-10 KTS FROM THE ENE AFTER 14Z FRI.

LOOKING BEYOND 18Z FRI... VFR CONDITIONS SHOULD DOMINATE THROUGH AT
LEAST SUNDAY... ALTHOUGH MVFR FOG IS POSSIBLE EARLY SAT MORNING AS
THE LIGHT ONSHORE LOW LEVEL FLOW PERSISTS. A PERIOD OF MVFR CIGS IS
POSSIBLE LATE SUN INTO SUN NIGHT AHEAD OF A COLD FRONT. VFR
CONDITIONS SHOULD THEN RETURN FOR MON/TUE WITH HIGH PRESSURE
BUILDING IN FROM THE NW. -GIH

&&

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

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD/WSS
SHORT TERM...WSS
LONG TERM...MWS
AVIATION...HARTFIELD


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