-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 092306
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
706 PM EDT WED JUL 9 2014

.SYNOPSIS...A WEAKENING COLD FRONT WILL MOVE INTO OUR REGION
THROUGH THURSDAY...THEN DRIFT TOWARD THE COAST FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 PM WEDNESDAY...

WIDELY SCATTERED SHOWERS AND TSTMS HAVE DEVELOPED ACROSS OUR
AREA...ESP ON THE EASTERN EDGE OF THE MID/HI CLOUD BAND THAT HAS
BEEN POSITIONED ACROSS THE WESTERN HALF OF THE CAROLINAS SO FAR
TODAY. LATEST MESOANALYSIS SHOWS THAT BEST INSTABILITY IS CURRENTLY
LOCATED EAST OF THE TRIANGLE...AND A SMALL POCKET OF ENHANCED
INSTABILITY ACROSS THE NW PIEDMONT WHERE A BREAK THE CLOUDS RECENTLY
DEVELOPED. ELSEWHERE ACROSS OUR CENTRAL ZONES...CLOUDS HAVE SO FAR
KEPT TEMPS AND INSTABILITY DOWN. IT`S WORTH NOTING THAT DCAPE IS
PARTICULARLY IMPRESSIVE FROM KFAY SOUTH AND EAST...SO IF A DEEP TSTM
CELL WITH AN ELEVATED CORE CAN DEVELOP IN THAT AREA...THE CHANCE FOR
A DAMAGING WIND GUST LOOKS PRETTY GOOD. ELSEWHERE...THE CHANCE FOR
SEVERE STORMS WILL BE LIMITED BY MODEST DEEP LAYER SHEAR...BUT
CERTAINLY THE RISK FOR AN ISOLATED STRONG STORM OR TWO CAN`T BE
RULED OUT.

THIS EVENING...CURRENT REGIONAL RADAR TRENDS ALONG WITH RECENT HRRR
RUNS SUGGEST THAT THE TSTM ACTIVITY NOW MOVING ACROSS THE CNTRL
APPALACHIANS (CLOSER TO THE COLD FRONT) WILL MOVE SE AND ACROSS OUR
WESTERN AND NORTHWEST PIEDMONT ZONES DURING THE EARLY EVENING
HOURS...THEN ACROSS THE REST OF OUR CWA A FEW HOURS EITHER SIDE OF
MIDNIGHT...BEFORE WINDING DOWN BEFORE SUNRISE. WHILE AN ISOLATED
STRONG OR DAMAGING WIND GUST CAN`T BE RULED OUT WITH ANY OF THE
STRONGER CELLS WITHIN THIS BATCH OF STORMS...ML CAPE DURING THAT
TIME WILL BE ON THE DOWNTURN AND DEEP LAYER SHEAR WILL STILL BE
SOMEWHAT MARGINAL FOR ORGANIZED CONVECTION.  AS SUCH...THE MAIN
IMPACTS OUTSIDE OF AN ISOLATED STRONG WIND GUST OR TWO WILL BE BRIEF
HEAVY DOWNPOURS. LOWS TONIGHT WILL RANGE FROM UPPER 60S NW TO LOWER
70S SE.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 230 PM WEDNESDAY...

SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR AGAIN ON THURSDAY AS
A SERIES OF WEAK DISTURBANCES MOVE NE ACROSS OUR AREA IN ADVANCE OF
THE MID-LEVEL TROUGH AXIS TO OUR WEST. AT THE SFC...THE COLD FRONT
CURRENTLY TO OUR NW WILL DROP SOUTH AND MERGE WITH THE PIEDMONT
TROUGH...PROVIDING A LOW LEVEL FOCUS FOR CONVECTION INITIATION.
NOTED THAT GUIDANCE SHOWS AN AXIS OF HIGH PWAT (AROUND 2 INCHES)
WILL PERSIST ACROSS THE EASTERN 2/3 OF OUR CWA DURING THE AFTERNOON
INTO THE EVENING...TRENDING LOWER TO AROUND 1.5 INCHES ACROSS THE
TRIAD. MEANWHILE...DEEP LAYER SHEAR WILL BE SIMILAR TO TODAY...25KT
OR LESS. THUS...WHILE WE CAN`T RULE OUT THE POTENTIAL FOR AN
ISOLATED STRONG WIND GUST OR TWO...THE MAIN IMPACTS MAY INSTEAD BE
HEAVY RAIN INVOF OF THE BELT OF HIGH PWAT...AND THE POTENTIAL FOR
LOCALIZED POOR DRAINAGE FLOODING WITH ANY OF THE SLOWER CELLS OR
LOCATIONS THAT SEE REPETITIVE DOWNPOURS. GIVEN THIS MOISTURE
PROFILE...LOOK FOR THE BEST COVERAGE AND THUS HIGHEST POPS TO BE
EAST OF THE TRIAD. SIMILAR TO TODAY...HIGHS WILL BE DEPENDENT ON
CLOUD COVEAGE...WHICH MAY BE MORE WIDESPREAD ACROSS OUR CWA TOMORROW
COMPARED TO TODAY. HIGHS IN THE MID-UPR 80S AND LOWS THURSDAY NIGHT
IN THE UPPER 60S TO AROUND 70.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 245 PM WEDNESDAY...

FOR FRI THROUGH SAT NIGHT: THE WEAKENING MID LEVEL TROUGH AXIS
SHIFTS EAST OF THE SRN APPALACHIANS FRI... BEFORE SWEEPING OVERHEAD
FRI NIGHT AND TO OUR EAST SAT. THE WEAK SURFACE TROUGH WILL ROUGHLY
FOLLOW THIS PACE AS WELL... SETTLING OVER THE COASTAL CAROLINAS BY
SAT MORNING BEFORE LARGELY DISSIPATING. THE EASTERN HALF OF NC WILL
REMAIN WITHIN SUFFICIENTLY DEEP MOISTURE FRI FOR MAINLY
AFTERNOON/EVENING SHOWERS AND STORMS... WHILE A DRIER COLUMN...
SLIGHT RISE IN HEIGHTS ALOFT... AND DOWNSLOPE LOW LEVEL FLOW OVER
THE WEST WILL LIMIT CONVECTION THERE... A PATTERN SUPPORTED BY THE
LATEST SREF PROBABILITIES OF CONVECTIVE PRECIP. THE GFS SHOWS MUCAPE
PEAKING AT 1500-2000 J/KG BUT SUBPAR DEEP LAYER SHEAR OF JUST AROUND
20 KTS OR SO... SO EXPECT ANOTHER ROUND OF WEAKLY FORCED AND SLOW
MOVING MULTICELL CLUSTER WITH SUPPRESSED SEVERITY BUT THE POTENTIAL
FOR TRAINING CELLS AND LOCALLY HEAVY RAIN GIVEN THE PW HOLDING NEAR
2.0 INCHES EAST OF HIGHWAY 1. THE SHEAR AXIS BROADENS AND WEAKENS
FURTHER ON SAT WITH MINOR RISES IN HEIGHTS ALOFT. ANY TRACE OF THE
SURFACE TROUGH IS TOUGH TO DETECT ON THE MODEL OUTPUT WITH A FAIRLY
UNIFORM LIGHT LOW LEVEL FLOW FROM THE S AND SE. MODELS SHOW CENTRAL
AND WRN NC WITHIN A RELATIVE PW MINIMUM... BETWEEN THE 1.5+ INCH
VALUES OVER COASTAL NC AND ERN SC... AND THE HIGHER VALUES PUSHING
INTO THE OH VALLEY ASSOCIATED WITH WHAT WILL LIKELY BE AN MCS
CROSSING THE MIDWEST AND SOUTHERN END OF THE GREAT LAKES SAT/SAT
NIGHT. BUT ANY AMOUNT OF ATLANTIC-SOURCE LOW LEVEL INFLOW COMBINED
WITH HEATING COULD GENERATE DISORGANIZED ISOLATED TO SCATTERED PULSE
CONVECTION IN THE AFTERNOON. WILL HAVE POPS ON THE LOW END... 20-30%
ORIENTED NW TO SE RESPECTIVELY... SAT AFTERNOON/EVENING.
THICKNESSSES BOTH FRI AND SAT STAY SLIGHTLY BELOW NORMAL... WITH A
BIT MORE SUNSHINE ANTICIPATED SAT THAN FRI... SO WILL HOLD ONTO
HIGHS FROM THE MID 80S TO NEAR 90 WITH LOWS IN THE UPPER 60S TO
LOWER 70S.

FOR SUN-WED: DEEP LAYER WIND FIELDS REMAIN VERY WEAK SUNDAY WITH
ONLY A SUBTLE SURFACE TROUGH EVIDENT THROUGH THE PIEDMONT... HOWEVER
WE WILL START TO SEE PW VALUES RECOVER BACK UP ABOVE SEASONAL
NORMALS... SUGGESTING A TREND BACK TO MORE SEASONALLY TYPICAL
COVERAGE OF AFTERNOON PULSE CONVECTION FOR SUNDAY. AN ANOMALOUSLY
STRONG MID LEVEL VORTEX (MID LEVEL HEIGHTS AS LOW S 2-3 STANDARD
DEVIATIONS BELOW NORMAL) AS LOW AS WILL WOBBLE EASTWARD ACROSS SRN
ONTARIO AND THE NRN GREAT LAKES SUN-TUE THEN INTO QUEBEC WED... AND
THIS BROAD TROUGHING OVER ERN NOAM WILL MEAN INCREASINGLY UNSETTLED
WEATHER FOR NC... WITH SW LOW LEVEL AHEAD OF THE SLOWLY APPROACHING
SURFACE COLD FRONT... AND STRENGTHENING MID LEVEL WESTERLY FLOW
FOSTERING BETTER STORM ORGANIZATION. WILL PLACE GOOD CHANCES OF
SHOWERS AND STORMS FOCUSED ON EACH AFTERNOON/EVENING MON-TUE... WITH
PERHAPS A SOUTHEASTWARD SHIFT OF THE HIGHER POPS WED TO LEVERAGE THE
POSSIBILITY THAT THE SURFACE FRONT MIGHT DROP SE INTO THE CWA AND
PUSH THE BETTER MOISTURE INTO SRN/ERN NC. SEE NOTHING TO INDICATE A
MAJOR DEPARTURE FROM CLIMATOLOGICAL TEMPS... AS GREATER-THAN-USUAL
CLOUD COVER WITH HEATING EACH DAY WILL MODULATE SLIGHTLY ABOVE-
NORMAL THICKNESSES... SO WILL STICK WITH DAILY HIGHS IN THE UPPER
80S TO LOWER 90S... AND DAILY LOWS NEAR 70 TO THE LOWER 70S. -GIH

&&

AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 700 PM WEDNESDAY...

24 HOUR TAF PERIOD: SHOWERS AND THUNDERSTORMS CURRENTLY AFFECTING
THE TRIAD WILL MOVE EASTWARD OVER THE NEXT SEVERAL HOURS. ANOTHER
BOUNDARY IN THE EXTREME EASTWARD SIDE OF THE AREA IS ALSO PRODUCING
CONVECTION BUT SHOULD MOVE OFF TO THE EAST. ALL IN ALL CONVECTION
SEEMS TO BE WINDING DOWN WITH THE EXCEPTION BEING MAYBE ACROSS THE
NORTH AND EAST. WILL CONTINUE TO MENTION SHOWERS IN THE TAFS AT KRDU
AND KRWI AS THEY ARE THE MOST LIKELY TO BE AFFECTED OVER THE NEXT
SEVERAL HOURS. EXPECT LIGHT SOUTHWESTERLY WINDS OVERNIGHT AT 5-10
KTS. THERE COULD BE POCKETS OF FOG OR LOW STRATUS
OVERNIGHT..ESPECIALLY WHERE THERE HAS BEEN CONVECTION BUT CONFIDENCE
IN THIS IS LOW AND IT WILL BE LEFT OUT OF THE TAFS AT THIS TIME.
THERE MAY BE SOME IMPROVED CONDITIONS AROUND DAYBREAK BUT THESE WILL
QUICKLY GO DOWN HILL DURING THE AFTERNOON AS CONVECTION IS EXPECTED
TO BE FAIRLY WIDESPREAD AS A COLD FRONT MOVES IN FROM THE NORTHWEST.
WILL COVER WITH A PROB 30 GROUP AFTER 18Z BUT A GOOD CHANCE FOR
PROLONGED MVFR CONDITIONS AT ALL SITES TOMORROW AFTERNOON WITH
CEILINGS NEAR 3 KFT AND 5 SM VISIBILITIES POSSIBLE. THIS IS EXPECTED
TO CONTINUE THROUGH THE END OF THE TAF PERIOD.

LONG TERM: THERE WILL BE CONTINUED CHANCES FOR SUB-VFR CONDITIONS
THROUGH MONDAY WITH THE LEAST COVERAGE SATURDAY AND SUNDAY BUT STILL
A CHANCE FOR DIURNAL CONVECTION...ESPECIALLY IN THE EAST.

&&

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

&&

$$

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