Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 252319
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
719 PM EDT SAT OCT 25 2014

.SYNOPSIS...A DRY NORTHWEST FLOW ALOFT WILL PREVAIL OVER THE
CAROLINAS THROUGH THE WEEKEND AS AN UPPER LEVEL RIDGE PROGRESSES
SLOWLY EASTWARD FROM THE ROCKIES TO THE MISSISSIPPI RIVER VALLEY.
WARM AND DRY CONDITIONS ARE EXPECTED EARLY TO MID WEEK... BEFORE A
TURN TO COLDER WEATHER BY THE END OF THE WEEK.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
AS OF 155 PM SATURDAY...

THROUGH TONIGHT: SYNOPTIC SUBSIDENCE IN THE WAKE OF A RECENT
SHORTWAVE PASSAGE HAS REINFORCED THE DRY/STABLE AIRMASS IN PLACE
ACROSS THE CAROLINAS (AS EVIDENCED BY A COMPARISON OF 00/12Z RAOB
DATA)... ENSURING A CONTINUATION OF CLEAR SKIES AND DRY CONDITIONS
THROUGH TONIGHT. WESTERLY LOW-LEVEL FLOW WILL RESULT IN MODEST LOW-
LEVEL WARM ADVECTION (H925 +2C TO +4C) ACROSS CENTRAL NC THIS
AFTERNOON AS UPSTREAM HEIGHTS RISE IN ADVANCE OF AN UPPER LEVEL
RIDGE PROGRESSING SLOWLY EAST FROM THE ROCKIES INTO THE MS RIVER
VALLEY. AS A RESULT...ANTICIPATE HIGH TEMPS A FEW DEGREES WARMER
THAN PRIOR DAYS...IN THE LOWER/MID 70S. THE MSLP/HEIGHT GRADIENT
WILL TIGHTEN OVERNIGHT AS AN AMPLIFYING UPPER LEVEL LOW (IN ONTARIO
AT 15Z) DIGS SOUTHEAST INTO NEW ENGLAND...MAINTAINING A LIGHT
WESTERLY BREEZE OVER CENTRAL NC. NOCTURNAL MIXING ASSOCIATED WITH A
LIGHT W/NW BREEZE IS EXPECTED TO PREVENT FULL RADIATIONAL
COOLING...AND THIS WILL BE THE BASIS FOR INDICATING OVERNIGHT LOWS
IN THE LOWER 50S. GIVEN OTHERWISE FAVORABLE CONDITIONS FOR RAD
COOLING...IT SHOULD BE NOTED THAT A BRIEF (2-3 HR) PERIOD OF CALM
WINDS WOULD PROBABLY BE SUFFICIENT FOR TEMPS TO QUICKLY FALL INTO
THE UPPER 40S.

SUN/SUN NIGHT: THE UPPER LEVEL LOW DIGGING INTO NEW ENGLAND LATE
TONIGHT WILL LIFT NORTHEAST INTO THE CANADIAN MARITIMES SUN/SUN
NIGHT. MEANWHILE...AN UPSTREAM RIDGE OVER THE CENTRAL CONUS WILL
PROGRESS EASTWARD THROUGH THE TN/OH VALLEY TO THE WESTERN SLOPES OF
THE APPALACHIANS BY 12Z MON. COLD ADVECTION IS EXPECTED ACROSS
CENTRAL NC SUN MORNING IN THE WAKE OF A DRY COLD FRONT TRAILING THE
POTENT UPPER LEVEL LOW DIGGING INTO NEW ENGLAND. COLD ADVECTION WILL
BE SHORT-LIVED IN MOST LOCATIONS...HOWEVER...AS WARM ADVECTION
ATTENDANT THE ADVANCING UPPER LEVEL RIDGE RETURNS BY EARLY AFTERNOON
IN ALL AREAS EXCEPT THE NE COASTAL PLAIN. GIVEN THAT MOS GUIDANCE
HAS BEEN CONSISTENTLY TOO WARM THE PAST SEVERAL DAYS...HAVE OPTED TO
DECREASE HIGHS A FEW DEGREES FROM THE PRIOR FORECAST TO THE LOW/MID
70S...COOLEST IN THE NE COASTAL PLAIN...WITH A NORTHWEST BREEZE AT
~15 MPH GUSTING UP TO 25 MPH. HIGH PRESSURE WILL BUILD OVER CENTRAL
NC/VA FROM THE WEST SUN NIGHT. GIVEN CLEAR SKIES/CALM WINDS AND A
DRIER AIRMASS ADVECTING INTO THE AREA IN THE WAKE OF THE DRY FRONTAL
PASSAGE EARLIER IN THE DAY...EXPECT GOOD RADIATIONAL COOLING WITH
LOWS IN THE LOW/MID 40S. -VINCENT

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 315 PM SATURDAY...

WARM AND DRY MONDAY INTO WEDNESDAY...

THE SURFACE HIGH PRESSURE IS FORECAST TO SHIFT OFFSHORE MONDAY
AFTERNOON AND NIGHT. THIS WILL GRADUALLY ALLOW A SW FLOW TO RETURN
TO THE REGION BY LATE MONDAY AND ESPECIALLY BY TUESDAY. SINCE THE
STRONGEST WAA IS EXPECTED TUESDAY... THAT WILL LIKELY BE THE WARMEST
DAY THIS UPCOMING PERIOD. HIGHS MONDAY SHOULD REACH THE MID 70S WITH
UPPER 70S TO NEAR 80 OVER THE SANDHILLS. LOWS WILL BE IN THE MID 40S
TO LOWER 50S MONDAY... WARMING INTO THE LOWER TO MID 50S TUESDAY AND
WEDNESDAY. HIGHS WEDNESDAY SHOULD BE TEMPERED BY SOME INCREASE IN
CLOUDS (EXPECT MOSTLY MID TO UPPER 70S).

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 315 PM SATURDAY...

...INCREASING ODDS OF THE FIRST FREEZE BY NEXT WEEKEND...

...PATTERN CHANGE TO COLDER WEATHER FROM THE GREAT LAKES TO THE SE
COAST LATE IN THE WEEK...

WHILE OPERATIONAL MODELS CONTINUE TO SHOW LARGE SPREAD OF SOLUTIONS
FOR OUR REGION MID TO LATE WEEK... THEY HAVE BEEN TRENDING TOWARD A
DEEPER AND COLDER UPPER TROUGH DEVELOPMENT FROM THE GREAT LAKES TO
THE TENNESSEE VALLEY TO THE EAST COAST BY FRIDAY AND SATURDAY. THIS
WOULD ALLOW A GOOD PUSH OF CONTINENTAL POLAR AIR... DRIVEN BY A
1035+ SURFACE HIGH PRESSURE... TO DIVE INTO THE CENTRAL AND EASTERN
STATES FRIDAY AND SATURDAY. WHILE A LOT IS YET TO BE DETERMINED
LIKELY DRIVEN BY THE REMNANTS OF ANA AS IT DRIVES INTO THE ALASKA
PANHANDLE. THE EUROPEAN AND ITS ENSEMBLES INDICATE A DEEPER AND MORE
CUT OFF MID/UPPER TROUGH OVER OUR REGION BY SAT-SUN... WHILE THE GFS
IS NOT AS STRONG. REGARDLESS... A BLEND OF THE ENSEMBLES AND TRENDS
STRONGLY SUGGEST AT LEAST A ROBUST MID/UPPER TROUGH OVER THE EASTERN
STATES. THE MORE EXTREME EUROPEAN MAY STILL DEVELOP... BUT IS STILL
CONSIDERED A LOW PROBABILITY AT THIS TIME.

THE BOTTOM LINE... THE PROBABILITY OF THE FIRST KILLING FROST OR
FREEZE FOR OUR REGION IS INCREASING FOR NEXT WEEKEND. HIGHS MAY
REMAIN IN THE 50S BY SATURDAY... WITH LOWS BY SATURDAY NIGHT
POTENTIALLY ENDING THE GROWING SEASON FOR MOST OF OUR WESTERN AND
NORTHERN ZONES IF NOT MORE OF THE REGION.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 715 PM SATURDAY...

24-HOUR TAF PERIOD: HIGH CONFIDENCE THAT VFR CONDITIONS WILL
DOMINATE THE TAF PERIOD. A WEAK WAVE IS EXPECTED TO MOVE ACROSS THE
AREA TONIGHT...AND WHILE SKIES SHOULD REMAIN CLEAR...WINDS MAY
REMAIN GENERALLY WESTERLY AT 3-6 KTS. THERE IS A CHANCE WINDS COULD
BECOME LIGHT OVERNIGHT...HOWEVER CONFIDENCE IN THAT HAPPENING IS NOT
HIGH AT THIS TIME. WITH THE HIGH APPROACHING FROM THE WEST AND THE
LOW LINGERING OVER NEW ENGLAND SUNDAY...EXPECT WINDS TO BECOME
NORTHWESTERLY AND INCREASE TO 10-12 KTS WITH GUSTS OF 18-25 KTS
DURING THE DAY SUNDAY. GUSTS SHOULD ABATE AROUND SUNSET SUNDAY. -KC

LOOKING AHEAD: VFR CONDITIONS WILL PERSIST THROUGH THE MIDDLE OF
NEXT WEEK IN ASSOCIATION WITH A PERSISTENTLY BENIGN SYNOPTIC
PATTERN. -VINCENT

&&

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

&&

$$

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



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