Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 021441
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1040 AM EDT THU JUL 2 2015

.SYNOPSIS... A SURFACE TROUGH WILL LINGER OVER THE PIEDMONT THIS
AFTERNOON. MEANWHILE...A COLD FRONT WILL SETTLE SLOWLY SOUTH AND
STALL OVER THE MIDDLE ATLANTIC STATES TONIGHT THROUGH THE HOLIDAY
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1040 AM THURSDAY...

INITIAL WEAK S/W LIFTING NEWD AND EXITING OUR COASTAL PLAIN COUNTIES
AT 14Z. EARLIER ISOLATED SHOWER ACTIVITY HAS PRETTY MUCH DRIED UP
AND EXTENSIVE DECK OF MID LEVEL CLOUDS HAS BEGUN TO ERODE/DIMINISH
ACROSS THE AREA. WATER VAPOR IMAGERY DEPICTS A VORTICITY MAXIMUM
OVER EASTERN TN. THIS SYSTEM CURRENTLY HANDLED WELL BY NEAR TERM
MODELS. PARTIAL SUN OVER THE AREA EARLY THIS AFTERNOON SHOULD
PRODUCE ADEQUATE SURFACE BASED INSTABILITY TO INITIATE/SUSTAIN
CONVECTION. THE APPROACH OF THE MID LEVEL VORT MAX SHOULD ENHANCE
THE CONVECTION SO THAT WE SHOULD SEE DECENT COVERAGE OF
CONVECTION...PRIMARILY OVER THE WESTERN AND NORTHERN PIEDMONT WHERE
THE 12Z 850MB ANALYSIS DEPICTS AN ELONGATED SW-NE ORIENTATED TROUGH.

LATEST SPC MESO SCALE ANALYSIS DEPICTS MODEST BULK SHEAR ON THE
ORDER OF 20-25KTS OVER A SMALL PART OF THE PIEDMONT. ENOUGH SHEAR
MAY EXIST TO CAUSE CONVECTION TO FORM IN BROKEN BANDS WHICH MAY
CONTRIBUTE TO AN INCREASE RISK FOR STRONG/LOCALLY DAMAGING WIND
GUSTS.

TEMPS THIS AFTERNOON STILL APPEAR ON TRACK TO REACH THE MID-UPPER
80S. HOWEVER...IF CONVECTION BECOMES SCATTERED PRIOR TO 19Z...SOME
PLACES MAY SEE MAX TEMPS NEAR 80/LOWER 80S. -WSS

TONIGHT: INITIAL SHOWERS AND STORMS WILL GRADUALLY DIMINISH/MOVE ENE
THIS EVENING. HOWEVER...A TRAILING SHORTWAVE TROUGH AND SEPARATE
CONVECTIVE CLUSTER/MCV OVER THE NORTHERN PLAINS THIS MORNING WILL
AMPLIFY... AMIDST CONTINUED CYCLONIC FLOW ALOFT...INTO THE TN VALLEY
AND SOUTHERN-CENTRAL APPALACHIANS BY FRI MORNING. ASSOCIATED RENEWED
FORCING FOR ASCENT WILL PROVIDE FOR SHOWER AND STORM REDEVELOPMENT
OR MAINTENANCE FROM UPSTREAM...PARTICULARLY OVER THE NORTHERN
PIEDMONT/NEAR THE VA BORDER...IN CLOSEST PROXIMITY TO THE
SYNOPTIC/DEEPER FRONTAL ZONE FORECAST TO SETTLE SOUTH THROUGH VA
DURING THE NEXT 24 HOURS. CONSIDERABLE CLOUDINESS OVERNIGHT WILL
LIKELY RESULT IN LOW TEMPERATURES A DEGREE OR TWO ABOVE GUIDANCE -
69-74.

&&

.NEAR TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 425 AM THURSDAY...

WHILE THE MODELS INDICATE THE SYNOPTIC FRONTAL ZONE WILL REMAIN NEAR
THE VA BORDER...NUMEROUS OUTFLOW BOUNDARIES WILL MODULATE THE
EFFECTIVE FRONT AND LIKELY CAUSE IT TO SAG SOUTH INTO CENTRAL NC
THIS PERIOD. CONVERGENCE AND DIFFERENTIAL HEATING ABOUT THE
FRONT(S); THE EASTWARD MIGRATION OF THE AFOREMENTIONED SHORTWAVE
TROUGH ACROSS THE CENTRAL APPALACHIANS; AND LOWER THAN PREVIOUS DAYS
LCL/LFC HEIGHTS AND CINH...WILL SUPPORT THE DEVELOPMENT OF NUMEROUS
SHOWERS AND STORMS BY MIDDAY-EARLY AFTERNOON. CONTINUED SEASONABLY
STRONG MID LEVEL FLOW AROUND 30 KTS WILL SUPPORT ADDITIONAL MULTI-
CELL STORM ORGANIZATION WITH AN ATTENDANT PRIMARY THREAT OF DAMAGING
WET MICROBURST WIND GUSTS...AND LOCALIZED FLOODING FOR STORMS
TRAINING ALONG THE GENERALLY EAST TO WEST-ORIENTED FRONT/OUTFLOW.
HOWEVER...A FEW STORMS MAY DISPLAY TRANSIENT SUPERCELL/ROTATIONAL
CHARACTERISTICS OWING TO ENHANCED LOW LEVEL SHEAR INVOF THE
BOUNDARY.

WHILE THE BRUNT OF THE SHOWERS AND STORMS ARE LIKELY TO MOVE NE OF
CENTRAL NC IN ASSOCIATION WITH A FRONTAL WAVE FORECAST TO TRACK
ALONG THE FRONT AND OFFSHORE THE VA COAST FRI NIGHT...HIGH PWAT
VALUES AND MINIMAL CINH...DESPITE PRIOR CONVECTIVE OVERTURNING/WEAK
INSTABILITY...WARRANTS A CONTINUED SLIGHT-LOW CHANCE OF SHOWERS AND
STORMS OVERNIGHT. LOWS IN THE UPPER 60S TO LOWER 70S.


&&

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

THE ACTIVE WEATHER PATTERN WILL CONTINUE THIS WEEKEND AND INTO AT
LEAST EARLY NEXT WEEK AS A BROAD UPPER TROUGH PERSISTS OVER THE
EASTERN US.  A SERIES OF DISTURBANCES IN THE WEST-NORTHWEST FLOW
ALOFT WILL BRING PERIODS OF ENHANCED CONVECTIVE COVERAGE THAT WILL
LIKELY BE A LITTLE BETTER FOCUSED NEAR A STALLED FRONT AND
CONFLUENCE ZONE THAT IS FORECAST TO MEANDER FROM SOUTHERN VA INTO
CENTRAL NC.  CONFIDENCE IN THE TIMING AND AMPLITUDE OF THESE WAVES
IS LOW GIVEN THE EXPECTED COVERAGE OF UPSTREAM CONVECTION EACH
DAY...BUT THE ECMWF AND GFS BOTH SUGGEST THE POTENTIAL FOR A
STRONGER SHORTWAVE ON SUNDAY THAT MAY SHIFT THE BEST COVERAGE FROM
THE NORTHERN CWA ON SATURDAY TO MORE AREAWIDE ON SUNDAY... AND THEN
TO SOUTHERN AND EASTERN AREAS ON MONDAY.  HIGH PW AND MODEST MID-
LEVEL FLOW ON THE EASTERN PERIPHERY OF THE UPPER TROUGH WILL SUPPORT
MAINLY A DAMAGING WIND SEVERE THREAT AND AT LEAST SOME MINOR URBAN
FLOODING POTENTIAL DEPENDING ON RAINFALL AMOUNTS IN PRECEDING DAYS.
HIGHS EACH AFTERNOON WILL BE A LITTLE BELOW NORMAL OWING TO THE
PERIODS OF CONVECTIVE ACTIVITY AND DEBRIS CLOUDING...WITH MOSTLY MID
80S NORTHWEST TO UPPER 90S SOUTHEAST EACH DAY SATURDAY THROUGH
MONDAY.  LOWS WILL BE IN THE UPPER 60S AND LOWER 70S.

THERE ARE SOME SIGNS OF WARMING FOR THE MIDDLE OF NEXT WEEK AND A
LITTLE LESS PRECIP COVERAGE AS THE PROGRESSIVE PATTERN EVENTUALLY
YIELDS SOME REESTABLISHMENT OF THE SUB-TROPICAL RIDGE OVER THE
SOUTHEAST US.  HOWEVER...THE OVERALL PATTERN IS NOT VERY AMPLIFIED
AND TEMPS SHOULD REMAIN WITHIN A FEW DEGREES OF NORMAL.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 710 AM THURSDAY...

CONSIDERABLE MID-HIGH CLOUDS...AND VIRGA OR VFR SHOWERS/
SPRINKLES...WILL SPREAD EAST ACROSS EAST-CENTRAL NC (INCLUDING RWI)
THIS MORNING IN ASSOCIATION WITH A PASSING MID LEVEL DISTURBANCE. AN
ADDITIONAL DISTURBANCE OR TWO WILL CROSS NC TODAY...AND ANOTHER LATE
TONIGHT. THE PASSAGE OF THESE FEATURES...IN CONJUNCTION WITH THE
APPROACH OF A COLD FRONT AND/OR OUTFLOW BOUNDARIES FROM UPSTREAM
CONVECTION...WILL RESULT IN AN INCREASE IN COVERAGE AND INTENSITY OF
SHOWERS AND STORMS THROUGH LATE THIS AFTERNOON-EVENING; AND SOME MAY
LINGER OR REDEVELOP OVERNIGHT.  OTHERWISE...AN INITIALLY LIGHT SSW
SURFACE WIND WILL INCREASE INTO THE 10-15 KT RANGE WITH GUSTS IN THE
UPPER TEENS TO AROUND 20 KTS THIS AFTERNOON.

OUTLOOK: THE AFOREMENTIONED FRONT WILL STALL OVER VA/NC AND RESULT
IN ABOVE AVERAGE PROBABILITIES OF SHOWERS AND STORMS AND ASSOCIATED
SUB-VFR CONDITIONS FRI-MON. PERIODS OF MVFR CEILINGS WILL BE
POSSIBLE EVEN OUTSIDE OF STORMS DURING THAT TIME...ESPECIALLY DURING
THE MORNING TO EARLY AFTERNOON HOURS.

&&

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

&&

$$

SYNOPSIS...26
NEAR TERM...WSS/26
SHORT TERM...26
LONG TERM...22
AVIATION...26



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