Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 080635
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
235 AM EDT WED JUL 8 2015

.SYNOPSIS...AN UPPER LEVEL RIDGE WILL STRETCH ACROSS THE SOUTHEAST
STATES THROUGH FRIDAY. THIS RIDGE WILL THEN DRIFT WESTWARD TO THE
SOUTHERN PLAINS OVER THE WEEKEND... AS A FRONT DROPS SOUTHWARD
THROUGH NORTH CAROLINA.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM WEDNSDAY...

A FRONTAL ZONE WILL REMAIN DRAPED ACROSS THE MID-ATLANTIC STATES AND
THROUGH THE OHIO VALLEY TODAY AS SURFACE HIGH PRESSURE AND A RIDGE
ALOFT BUILD IN FROM THE EAST. CENTRAL NC WILL BE LOCATED ON THE
NORTHERN PERIPHERY OF THE RIDGE AND WHILE SHOULD REMAIN MOSTLY
DRY...THERE WILL BE HIGHER CHANCES FOR PRECIPITATION ACROSS THE FAR
NORTH...ESPECIALLY AS SMALLER SHORTWAVES MOVE ALONG THE COLD FRONT.
IN ADDITION...FAR SOUTHEASTERN COUNTIES COULD SEE A SHOWER OR TWO IN
ASSOCIATION WITH SEA BREEZE AND DIURNAL EFFECTS IN THE RETURN FLOW
AROUND THE HIGH TO THE SOUTHEAST. CONVECTIVE ALLOWING MODELS ARE NOT
VERY BULLISH ON PRECIPITATION THIS AFTERNOON WITH ONLY A FEW
SCATTERED SHOWERS POPPING UP LATER IN THE DAY. THE CWA WILL STAY IN
THE RIGHT EXIT REGION OF AN 850 MB JET WHICH IS NOT VERY FAVORABLE
FOR INCREASED LIFT. THEREFORE WITH ONLY 10 KTS OF BULK SHEAR ACROSS
THE AREA...CONVECTION WILL HAVE TO DEPEND ON INSTABILITY FROM
HEATING AND AN INCREASE IN ATMOSPHERIC MOISTURE WHICH SHOULD
APPROACH TWO INCHES BY LATER THIS EVENING. HIGH TEMPERATURE WILL BE
WARM...REACHING THE LOW TO MID 90S.

CONVECTIVE ALLOWING MODELS ARE SHOWING AN UPTICK IN CONVECTION AFTER
DARK TONIGHT AS A 500 MB SHORTWAVE DIVES SOUTHWESTWARD OUT OF
SOUTHERN VA AND ACROSS THE NORTHEASTERN PORTION OF THE CWA. WHILE
THE EVOLUTION OF THIS IS UNCERTAIN AT THIS TIME...FORECAST SOUNDINGS
STILL SHOW SOME ELEVATED INSTABILITY WITH A GROWING NOCTURNAL
INVERSION AT 950 MB. IF CONVECTION WERE TO OCCUR...IT IS PROGGED TO
MOVE EAST AND OUT OF THE AREA BY 6Z. LOW TEMPS THURSDAY MORNING IN
THE UPPER 60S TO LOW 70S.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 235 AM WEDNESDAY...

SIMILAR STORY ON THURSDAY AS COLD FRONTAL ZONE STILL HANGING NORTH
OF THE AREA BUT GFS HAS IT MOVING SLIGHTLY SOUTHWARD AND ACROSS THE
NORTHERN TIER OF COUNTIES. NAM AND ECMWF SOLUTIONS HOWEVER KEEP THE
FRONT FURTHER NORTH AND THE AREA MOSTLY DRY ONCE AGAIN. THE LATTER
SOLUTIONS SEEM MORE PLAUSIBLE AS IT IS UNLIKELY THAT A WEAKENING
FRONTAL BOUNDARY WOULD BE ABLE TO PENETRATE THE STRONG HIGH AS MUCH
AS THE GFS IS SHOWING. WILL KEEP SLIGHT CHANCES ACROSS THE NORTH
WITH ONLY ISOLATED CONVECTION EXPECTED ELSEWHERE. ALL NOTABLE VORT
MAXIMA STAY NORTH OF THE AREA ON THURSDAY AND FORECAST SOUNDINGS
SHOW THE AREA NOT NEARLY AS MOIST AS ON WEDNEDAY EVENING. CONTINUED
SOUTHWESTERLY RETURN FLOW MEANS ANOTHER HIKE IN TEMPERATURES...WITH
HIGHS IN THE MID 90S IN MOST LOCATIONS. LOWS THURSDAY NIGHT IN THE
LOWER 70S.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 230 AM WEDNESDAY...

FRI: THE PATTERN CHANGE BEGINS FRI AS THE SPRAWLING MID LEVEL RIDGE
SHIFTS FURTHER TOWARD THE WEST... ALLOWING THE SYNOPTIC FRONT TO
DROP SOUTH-SOUTHWESTWARD INTO THE STATE AS THE WESTERLIES DIP
SOUTHWARD DOWN THE MIDATLANTIC REGION. MODELS DEPICT DRY WEATHER FOR
MUCH OF THE DAY... SHOWING PERHAPS ISOLATED CONVECTION ALONG THE
PIEDMONT TROUGH OVER THE SOUTHEAST CWA DURING THE EVENING AND
OVERNIGHT. THE NAM/ECMWF/CANADIAN SHOW (WITH SOME TIMING
DIFFERENCES) A VORTICITY MAX (POTENTIAL MCV) DROPPING THROUGH WV
TOWARD VA LATE FRI NIGHT... PRECEDED BY A WEAK SURFACE LOW TRACKING
ALONG THE FRONTAL ZONE... BUT IT APPEARS THAT ANY INFLUENCE OF SUCH
A FEATURE WOULD NOT BE REALIZED UNTIL AFTER SUNRISE SAT MORNING...
ALTHOUGH TRYING TO TIME SUCH FEATURES AT THIS TIME RANGE IS FRAUGHT
WITH UNCERTAINTY. WILL INCLUDE A LATE-DAY CHANCE POP IN THE
SOUTHEAST CWA EXTENDING THROUGH THE MIDNIGHT HOUR... WITH NO BETTER
THAN ISOLATED LATE-DAY AND EVENING POPS ELSEWHERE. DEEP LAYER SHEAR
IMPROVES A BIT BUT PROGGED MUCAPE HOLDS UNDER 750 J/KG... SO DON`T
EXPECT ANY SEVERE STORMS THROUGH FRI... ALTHOUGH HEAVY RAIN IS
POSSIBLE GIVEN LOCALLY ELEVATED PW APPROACHING 2.0 INCHES AND
SLOW/TRAINING CELL MOTION. A WELL MIXED BOUNDARY LAYER AND SLIGHTLY
ABOVE NORMAL THICKNESSES SUPPORT HIGHS OF 90-96.

SAT-TUE: PREDICTABILITY REGARDING THE TIMING AND LOCATION OF
PRECIPITATION DURING THIS PERIOD IS SOMEWHAT LOW. THE CONTINUED
RETROGRESSION OF THE MID LEVEL RIDGE WILL ALLOW HEIGHT FALLS FROM
THE UPPER MIDWEST THROUGH THE GREAT LAKES AND ALONG THE
APPALACHIANS... RESULTING IN MORE DEFINED NORTHWEST FLOW (INITIALLY
DIFFLUENT) TRENDING TO CYCLONIC WEST/SW FLOW BY TUE AS TROUGHING
DIGS JUST TO OUR WEST AND NW. GIVEN THE HIGH INSTABILITY FROM ERN ND
SOUTHEAST INTO IL SAT/SUN AND STRONG LOW LEVEL JET FEEDING INTO THIS
REGION... UPSTREAM MCS ACTIVITY APPEARS LIKELY... AND REMNANTS OF
THIS ACTIVITY COULD CERTAINTY TRACK SE INTO OUR REGION BASED ON THE
EXPECTED FLOW PATTERN. YET THE MODELS DON`T AGREE ON THE PRECIP
PATTERN... WITH THE GFS LARGELY DRY SAT/SUN WHILE THE ECMWF TAKES
ORGANIZED CONVECTION ACROSS NRN/ERN NC LATE SAT AND AGAIN LATE SUN.
WITH SUCH UNCERTAINTY... AND WITH BOTH DEEP LAYER SHEAR AND FORECAST
CAPE REMAINING MUTED THROUGH THE WEEKEND SUGGESTING THAT UPSTREAM
MCS ACTIVITY MAY NOT BE MAINTAINED... WILL KEEP POPS AT OR JUST
UNDER CLIMATOLOGY... 20-30% OVER THE WEEKEND... HIGHEST LATE IN THE
DAY AND EVENING. BY MON/TUE... THE DEVELOPING TROUGH TO OUR WEST AND
SUBSEQUENT INCREASE IN DPVA OVER NC ALONG WITH ELEVATED PW AND TREND
TOWARD STRONGER SOUTHWESTERLY 850-700 MB FLOW SHOULD TRANSLATE INTO
HIGHER POPS THESE TWO DAYS... ESPECIALLY TUE. AFTER NEAR TO SLIGHTLY
ABOVE NORMAL TEMPS SAT/SUN... EXPECT TEMPS NEAR OR JUST UNDER NORMAL
MON/TUE GIVEN THE IMPLICIT INCREASED CLOUD COVER. -GIH

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 145 AM WEDNESDAY...

24 HOUR TAF PERIOD: A GOOD CHANCE FOR VFR CONDITIONS THROUGH THE TAF
PERIOD AS WE BEGIN THE MORNING WITH DEWPOINT DEPRESSIONS OF AT LEAST
5 DEGREES ACROSS THE AREA AND A BROKEN CEILING AT 25 KFT WHICH WILL
MOST LIKELY INHIBIT ANY CHANCES OF FOG OR LOW STRATUS PRIOR TO
SUNRISE. RADAR IS CLEAR AT THIS TIME AND WHILE HIGH RESOLUTION
MODELS SHOW A CHANCE FOR A COUPLE OF POP UP DIURNAL SHOWERS THIS
AFTERNOON CONFIDENCE IN THAT OCCURRING IS NOT VERY HIGH AT THIS TIME
ALTHOUGH MOISTURE DOES INCREASE QUITE A BIT BY THIS EVENING. WINDS
MAINLY OUT OF THE SOUTHWEST AT 5-10 KTS WITH SOME AFTERNOON GUSTS OF
15-20 KTS.

LONG TERM: A LITTLE BIT OF A BREAK IN THE ACTIVE PATTERN WE HAVE
BEEN UNDER LATELY AS CENTRAL NC REMAINS UNDER THE INFLUENCE OF THE
UPPER LEVEL RIDGE. ASIDE FROM DIURNAL CONVECTION...NOT TOO MUCH TO
HINDER AVIATION CONDITIONS IN THE LONG TERM.

&&

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

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...ELLIS
SHORT TERM...ELLIS
LONG TERM...HARTFIELD
AVIATION...ELLIS


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