Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 201316
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
917 AM EDT SAT SEP 20 2014

.SYNOPSIS...A LOW PRESSURE SYSTEM WILL TRACK SLOWLY NORTHEAST ALONG
THE CAROLINA COAST THROUGH SUNDAY AS A COLD FRONT APPROACHES THE
MOUNTAINS FROM THE WEST. HIGH PRESSURE WILL BUILD INTO THE REGION
FROM THE NORTH EARLY TO MID NEXT WEEK...IN THE WAKE OF A DRY COLD
FRONTAL PASSAGE MONDAY MORNING.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 917 AM SATURDAY...

SATELLITE IMAGERY OF THE DEVELOPING LOW PRESSURE SYSTEM OFF THE
SOUTHEAST COAST IS VERY IMPRESSIVE THIS MORNING. ALTHOUGH MOISTURE
WILL INCREASE AND MID-LEVEL TEMPS WILL DECREASE HEADING EAST TOWARD
THE COAST...CENTRAL NC WILL LARGELY REMAIN ON THE SUBSIDENT SIDE OF
THE UPPER LEVEL TROUGH/COMPACT UPPER LOW. THUS...EXPECT THE CURRENT
EAST-WEST TREND IN CLOUD COVER WITH SIMILAR RAIN CHANCES TO PREVAIL
THROUGH TONIGHT/EARLY SUNDAY WITH THE BEST CHANCE OF PRECIPITATION
ALONG THE CAROLINA COAST....WITH A WEAKENING TREND IN THE SHOWER
ACTIVITY AS IT ATTEMPTS TO PUSH INLAND. WILL INDICATE SLIGHT TO
SMALL CHANCE POPS ACROSS THE FAR SE ZONES(SAMPSON/WAYNE/CUMBERLAND)
WITH DRY FORECAST ELSEWHERE. HIGHS GENERALLY IN THE LOWER 80S WITH
THE OPAQUE MID AND HIGH LEVEL CLOUD COVER ACROSS THE SE COUNTIES
SUFFICIENTLY OPAQUE TO SHAVE OFF A DEGREE OR TWO.

WITH LOSS OF DAYTIME HEATING...EXPECT DRY CONDITIONS WILL PREVAIL
EVERYWHERE OVERNIGHT. LOWS RANGING FROM THE UPPER 50S WEST TO MIDS
60S EAST.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 245 AM SATURDAY...

DRY/SUBSIDENT CONDITIONS WILL PREVAIL SUNDAY AS THE STALLED UPPER
LEVEL TROUGH BECOMES PROGRESSIVE...MOVING OFFSHORE WITH THE
ATTENDANT SFC LOW. POTENT SHORTWAVE ENERGY DIGGING THROUGH THE GREAT
LAKES INTO THE OH VALLEY WILL PROPEL A COLD FRONT EAST TOWARD THE
APPALACHIANS ON SUNDAY. THE FRONT WILL CROSS CENTRAL NC MONDAY
MORNING AS THE AFOREMENTIONED SHORTWAVE ENERGY TRACKS ACROSS THE
NORTHERN MID-ATLANTIC. POOR DIURNAL TIMING WILL LIKELY RULE OUT ANY
POTENTIAL FOR CONVECTION IN ASSOC/W THE FRONTAL PASSAGE...AND WILL
MAINTAIN DRY CONDITIONS EVERYWHERE THROUGH SUN NIGHT. HIGHS ON SUN
IN ADVANCE OF THE FRONT IN THE MID 80S...LOWS IN THE LOWER/MID 60S
GIVEN FROPA CLOSE TO SUNRISE. -VINCENT

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 330 AM SATURDAY...

DRY AND COOL TO START THE WEEK...THEN INCREASING CLOUDS/COOL LATE
WEEK...

A LARGE SPRAWLING SURFACE HIGH PRESSURE IS FORECAST TO PUSH A COLD
FRONT THROUGH OUR REGION EARLY MONDAY. MODELS ARE IN GOOD AGREEMENT
IN DEPICTING THE LACK OF MOISTURE ASSOCIATED WITH THE FRONTAL
PASSAGE. THEREFORE... ESSENTIALLY NIL POP AND QPF FOR MONDAY. GOOD
DRY AND COOL AIR ADVECTION WILL COMMENCE LATER MONDAY THROUGH
TUESDAY. DRY AND COOL CONDITIONS ARE FORECAST INTO WEDNESDAY
COURTESY OF THE STRONG HIGH.

MODELS HAVE YET TO RESOLVE DIFFERENCES IN SOLUTIONS FOR MID TO LATE
WEEK. SEVERAL OPERATIONAL MODELS INDICATE A WEAKNESS ALOFT OVER THE
SOUTHERN APPALACHIANS OR OVER OUR REGION BY THU-FRI. SOME MODELS AND
ENSEMBLES HAVE LESS IN THE WAY OF A WEAKNESS ALOFT. REGARDLESS... IT
DOES APPEAR THAT MOISTURE WILL BEGIN TO INCREASE FROM OFF THE
ATLANTIC AS THE SURFACE HIGH SHIFTS OFF THE NEW ENGLAND COAST
ESPECIALLY LATE WED INTO THU. JUST HOW DEEP THIS MOISTURE BECOMES
SHOULD BE DETERMINED BY THE HEIGHTS ALOFT WHICH MAY NOT BE RESOLVED
FOR A FEW MODEL CYCLES.

THEREFORE... THE ONLY CHANCES MADE TO THE FORECAST WERE TO INCREASE
TEMPERATURES A BIT MONDAY WITH MORE IN THE WAY OF SUN EXPECTED
(PARTLY SUNNY SKIES... BECOMING MOSTLY SUNNY IN THE AFTERNOON)...
AND LESS POP WITH THE EARLY MORNING COLD FRONTAL PASSAGE (NOW NIL).
HIGHS GENERALLY 77-82 N TO SE.

MUCH COOLER TUE-WED WITH SOME UPPER 40S IN THE COOLER RURAL PIEDMONT
AND SANDHILLS LOCATIONS UNDER MOSTLY CLEAR SKIES AT NIGHT... THEN
HIGHS ONLY 70-75 WITH MOSTLY SUNNY SKIES.

WE WILL SHOW A TREND TOWARD INCREASING CLOUDINESS AND LOWER
AFTERNOON HIGHS THU-FRI DUE TO THE ATLANTIC FLOW AND POTENTIAL FOR A
WEAKNESS ALOFT. POP MAY HAVE TO BE INCREASED IN LATER FORECASTS IF
THE EC/CANADIAN TEND TO VERIFY BETTER.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 730 AM SATURDAY...

24-HR TAF PERIOD: ASIDE FROM CURRENT LIFR/IFR FOG AND LOW CEILINGS
WHICH WILL SCATTER OUT BY 12-14Z...VFR CONDITIONS AND A LIGHT
NORTHEAST BREEZE WILL PREVAIL THROUGH THE TAF PERIOD AT THE
INT/GSO/RDU TERMINALS...LOCATED ON THE WESTERN PERIPHERY (SUBSIDENT
SIDE) OF AN UPPER LEVEL TROUGH OVER THE SOUTHEAST. VFR CONDITIONS
WILL PREVAIL FOR MOST (IF NOT ALL) OF THE TAF PERIOD AT THE FAY/RWI
TERMINALS...EXCEPT FOR A POTENTIAL FOR MVFR CEILINGS (BASES 2500-
3500 FT AGL) AND ISOLD SHOWERS DURING THE AFTERNOON IN ASSOC/W A
MOIST LOW-LEVEL EASTERLY FLOW OFF THE ATLANTIC.

LOOKING AHEAD: ASIDE FROM A SMALL CHANCE OF AN ISOLD SHOWER AT THE
INT/GSO TERMINALS AND A 10-15 KT WESTERLY BREEZE IN ADVANCE OF A
COLD FRONT APPROACHING THE REGION FROM THE WEST LATE SUNDAY
AFT/EVE...VFR CONDITIONS (AND A NORTHEASTERLY BREEZE) WILL PREVAIL
THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE
NORTH/NW. -VINCENT

&&

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

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...CBL/VINCENT
SHORT TERM...VINCENT
LONG TERM...PWB
AVIATION...VINCENT


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