Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 231726
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
126 AM EDT WED APR 23 2014

.SYNOPSIS...HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST THROUGH
THURSDAY. A COLD FRONT WILL APPROACH FROM THE WEST ON FRIDAY.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
AS OF 950 AM WEDNESDAY...

THROUGH TONIGHT: THE COLD FRONT HAS PUSHED THROUGH CENTRAL NC AND
OVER THE NEXT FEW HOURS WILL SEE DECREASING DEWPOINTS AND INCREASING
WINDS AND WIND GUSTS. WITH RH VALUES IN THE 20-30 PERCENT RANGE...
AND NW WINDS SUSTAINED AT 10-15 KTS...GUSTING TO 20-25 KTS THIS
AFTERNOON...WILL RESULT IN INCREASED FIRE DANGER. STILL EXPECT HIGHS
TODAY IN THE UPPER 60S ACROSS THE NORTH...TO MID 70S SOUTH.
TONIGHT...HIGH PRESSURE WILL BUILD INTO THE AREA. WINDS WILL
DECREASE AND SHIFT TO NORTH AND NORTHEAST...WITH CONTINUED CLEAR
SKIES. LOWS WILL RANGE FROM THE MID TO UPPER 30S ALONG THE VA
BORDER...TO LOW TO MID 40S ACROSS THE SOUTH. THE TEMPERATURE
CRITERIA FOR A FROST ADVISORY IS CURRENTLY LOWER THAN THE FORECAST
LOWS...THUS WILL NOT ISSUE ONE AT THIS POINT...HOWEVER THE CHANCE
FOR SOME VERY ISOLATED PATCHES OF FROST CANNOT BE RULED OUT
COMPLETELY. -KC

FOR THU/THU NIGHT: ANOTHER GENERALLY CLEAR DAY EXPECTED... WITH
ANOTHER REINFORCING FRONT DROPPING THROUGH FROM THE NORTH TO KNOCK
THICKNESSES BACK DOWN TO READINGS NEARLY 30 M BELOW NORMAL. DESPITE
PLENTY OF SUNSHINE WITH A SURFACE RIDGE NOSING IN FROM THE NORTH AND
WEAK MID LEVEL RIDGING BUILDING IN FROM THE WEST... WE SHOULD SEE
BELOW-NORMAL HIGHS OF 67-73. A WARM FRONTAL ZONE WILL APPROACH
CENTRAL NC FROM THE SW LATE THU NIGHT... RESULTING IN A
STRENGTHENING FLOW FROM THE SW AND QUICKLY INCREASING LOW LEVEL
MOISTURE FROM SW TO NE. MOIST ISENTROPIC UPGLIDE RAMPS UP AROUND
295K ESPECIALLY IN THE SW HALF OF THE CWA... SO WILL TREND TOWARD
INCREASING CLOUDINESS AREAWIDE AND MENTION PATCHY DRIZZLE OVER THE
FAR SW CWA (INCLUDING WINSTON-SALEM / ASHEBORO / ALBEMARLE /
WADESBORO / LAURINBURG) LATE THU NIGHT. MILDER LOWS OF 46-53. -GIH

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 325 AM WEDNESDAY...

A PROGRESSIVE SHORTWAVE AND ASSOCIATED SURFACE FRONTAL ZONE WILL
MOVE INTO THE TENNESSEE AND OHIO VALLEYS FRIDAY MORNING...THEN
ACROSS THE MOUNTAINS DURING THE DAY ON FRIDAY.  MODEL SOLUTIONS HAVE
ACTUALLY DIVERGED A BIT REGARDING THE TIMING OF THE BEST FORCING AND
SUBSEQUENT QPF.  THE GFS CONTINUES TO BE THE FASTER SOLUTION...WITH
THE UPPER TROUGH AND LOBE OF VORTICITY MOVING ACROSS CENTRAL NC BY
MIDDAY...WHILE THE TRAILING FRONTAL ZONE CROSSES THE AREA DURING THE
AFTERNOON AND EVENING.  THIS SEEMS TO SUGGEST POSSIBLE SHOWERS
EARLIER IN THE DAY LESS POTENTIAL FOR HEATING AND DESTABILIZATION
AHEAD OF THE FRONT.  THE ECWMF HAS TRENDED SHARPER AND A BIT DEEPER
WITH THE TROUGH...WHICH LEADS TO A SLOWER SOLUTION BUT BETTER
HEATING...PARTICULARLY OVER THE COASTAL PLAIN.  LOW-LEVEL MOISTURE
RETURN AHEAD OF THE FRONT IS WEAK BUT SHOULD ALLOW DEWPOINTS TO RISE
INTO THE UPPER 50S AND LOWER 60S...WHICH COMBINED WITH FORECAST
HIGHS IN THE 75-81 RANGE BUT WEAK MID-LEVEL LAPSE RATES...SHOULD
YIELD WEAK INSTABILITY...MAYBE 500-1000 J/KG MAINLY ACROSS THE SOUTH
AND EAST. DEEP LAYER IS FORECAST TO BE ON THE ORDER OF 25-
35KT...THOUGH STRONGEST TO THE NORTH AWAY FROM BETTER INSTABILITY.
POTENTIAL FOR SEVERE SEEMS LIMITED GIVEN THE MARGINAL
SHEAR/INSTABILITY...BUT THE SLOWER TREND WITH THE ECMWF AND STRONGER
DCVA WOULD SUPPORT A LITTLE BETTER CHANCE.  GIVEN THAT THE MID-LEVEL
FLOW WILL BE WESTERLY AND DRYING...WILL KEEP POPS IN THE CHANCE
RANGE WITH HIGHS IN THE MID 70S WEST TO LOWER 80S EAST.

THE COLD FRONT SHOULD PUSH EAST OF THE CWA BY MIDNIGHT FRIDAY NIGHT
AND BRING PRECIP CHANCES TO AN END.  A SECONDARY FRONTAL ZONE IS
FORECAST TO APPROACH BUT REMAIN NORTH OF THE AREA. THUS THE MAIN
SENSIBLE IMPACT WILL BE LOWER HUMIDITY ON SATURDAY...WITH FORECAST
HIGHS IN THE UPPER 70S AND LOWER 80S.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 325 AM WEDNESDAY...

THE PROGRESSIVE FLOW OVER THE CONUS THIS WEEK IS FORECAST TRANSITION
TO A MORE AMPLIFIED AND EVEN BLOCKED FLOW NEXT WEEK...THOUGH THE GFS
AND ECMWF DONT YET AGREE ON THE DEGREE OF BLOCKING IN THE FLOW.
IN GENERAL...A STRONG TROUGH WILL EJECT OUT OF THE SOUTHERN PLAINS
THIS WEEKEND AND THEN LIKELY CLOSE OFF INTO AN UPPER LOW OVER THE
MIDWEST STATES BY MONDAY.....WITH ANOTHER LOW OVER THE NORTHERN
ATLANTIC AND A SHORTWAVE RIDGE IN BETWEEN.   THE BIG QUESTION WILL
BE WHERE A FRONTAL ZONE TO OUR NORTH ENDS UP ON SUNDAY AND THEN HOW
QUICKLY PRECIP SPREADS EAST ALONG THE FRONT MONDAY AND TUESDAY AS
THE UPPER LOW MOVES SLOWLY TO THE EAST.  THE GFS SUGGEST THE FRONT
WILL UNDERCUT THE UPPER RIDGE AND SLIP BACKDOOR INTO THE AREA BY
SUNDAY...WHILE THE ECMWF KEEP THE FRONT WELL NORTH OF NC.  PRECIP
CHANCES SHOULD INCREASE DRAMATICALLY BY TUESDAY AS THE UPPER LOW
FINALLY MOVES EAST OF THE MISSISSIPPI RIVER.  TEMPS DURING THE TIME
FRAME WILL BE MOSTLY AROUND NORMAL...THOUGH UNCERTAINTY GROWS INTO
MONDAY AND TUESDAY AS THE POTENTIAL FOR CLOUD COVER AND PRECIP GROW.

&&

.AVIATION /18Z WEDNESDAY THROUGH SUNDAY/...
AS OF 120 PM WEDNESDAY

24 HOUR TAF PERIOD: HIGH CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL
THROUGH THE 24 HOUR TAF PERIOD. NORTHWESTERLY WINDS WILL REMAIN
STRONG (10-15 KTS) AND GUSTY (20-25 KTS) THROUGH THE AFTERNOON...
ABATING AFTER SUNSET AS NOCTURNAL STABILIZATION COMMENCES. HIGH
PRESSURE WILL MOVE INTO THE AREA OVERNIGHT...WITH CLEAR SKIES AND
LIGHT AND VARIABLE WINDS EXPECTED.

LOOKING AHEAD: THE NEXT CHANCE FOR ADVERSE AVIATION CONDITIONS WILL
BE LATE THURSDAY NIGHT/EARLY FRIDAY MORNING...LASTING THROUGH MOST
OF THE DAY FRIDAY. A WARM FRONT WILL LIFT NORTH THOUGH THE AREA
AHEAD OF A LOW PRESSURE SYSTEM APPROACHING FROM THE WEST. EXPECT
CONDITIONS IN THE IFR RANGE AS THE COLD FRONT APPROACHES AND RAIN
MOVES THROUGH THE AREA. CONDITIONS SHOULD IMPROVE BACK TO VFR BEHIND
THE FRONT FRIDAY NIGHT AND INTO SATURDAY MORNING. LIGHT WINDS AND
VFR CONDITIONS WILL PREVAIL FOR THE WEEKEND.

&&

.FIRE WEATHER /TODAY THROUGH EARLY THIS EVENING/...
AS OF 125 PM WEDNESDAY...

...INCREASED FIRE DANGER TODAY DUE TO GUSTY WINDS AND LOW HUMIDITY...

WINDS FROM THE NORTHWEST SUSTAINED AT 12-18 MPH WILL OCCASIONALLY
GUST TO 20-25 MPH. THESE WINDS...COMBINED WITH MINIMUM RELATIVE
HUMIDITY VALUES OF 21-27 PERCENT...AND SOMEWHAT LOW FINE FUEL
MOISTURE IN THE 7-8% RANGE...WILL POSE A THREAT FOR ADVERSE FIRE
BEHAVIOR THROUGH THIS EVENING. WILL REISSUE A SPECIAL WEATHER
STATEMENT ADDRESSING THE INCREASED FIRE DANGER...AND WILL CONTINUE
THE HEADLINE IN PRE-SUPPRESSION FIRE WEATHER PRODUCTS.

THE RH WILL BE A BIT HIGHER ON THU...WITH LIGHTER WINDS...HOWEVER
THE FINE FUELS ARE LIKELY TO BE EVEN DRIER. THEREFORE...THOSE
INVOLVED IN OUTDOOR BURNING SHOULD CONTINUE TO USE EXTRA CAUTION.

&&

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

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...KC/HARTFIELD
SHORT TERM...SMITH
LONG TERM... SMITH
AVIATION...KC
FIRE WEATHER...HARTFIELD



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