AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
140 AM EDT TUE SEP 2 2014  

.SYNOPSIS...AN AREA OF HIGH PRESSURE WILL EXTEND OVER THE REGION 
TODAY.  A WEAK SURFACE FRONT WILL SETTLE SOUTHWARD ACROSS CENTRAL NC 
ON WEDNESDAY. HIGH PRESSURE WILL BUILD BACK OVER THE AREA FOR THE 
REMAINDER OF THE WORK WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/... 
AS OF 1010 PM MONDAY...

MID LEVEL RIDGE... CENTERED TO THE SSW OF CENTRAL NC OVER THE DEEP 
SOUTH... WILL EXTEND INTO OUR REGION TONIGHT. HOWEVER... WEAK 
DISTURBANCES IN THE WESTERLY MID LEVEL FLOW WILL HELP TO KEEP SKIES 
PARTLY CLOUDY AT TIMES. THE LATEST HI-RES GUIDANCES CONTINUES TO 
KEEP DRY CONDITIONS OVER CENTRAL NC THOUGH. THUS... WILL CONTINUE A 
DRY FORECAST FOR TONIGHT WITH MOSTLY CLEAR TO PARTLY CLOUDY SKIES. 
LOWS TUESDAY MORNING ARE EXPECTED TO BE NEAR 70/LOWER 70S TO MID 70S 
SE. 

WILL LIKELY SEE PATCHES OF FOG DEVELOP AFTER MIDNIGHT...MAINLY OVER 
THE COASTAL PLAIN..SANDHILLS AND EASTERN PIEDMONT. HOWEVER DENSE FOG 
WILL BE RARE WITH BULK OF THE VISIBILITIES AT OR ABOVE 1-2 MILES. 

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... 
AS OF 305 PM MONDAY...

TUESDAY AND TUESDAY NIGHT... MID-UPPER LEVEL RIDGE PROJECTED TO 
SLOWLY WEAKEN THIS PERIOD. THIS MAY ALLOW A FEW MORE T-STORMS TO 
DEVELOP IN THE SLIGHT-MODERATELY UNSTABLE AIR MASS TUESDAY AFTERNOON-
EVENING. IN ADDITION...A S/W RESPONSIBLE FOR TRIGGERING THE 
CONVECTION ACROSS PARTS OF THE MISSOURI VALLEY/OZARKS THIS AFTERNOON-
EVENING WILL APPROACH CENTRAL NC FROM THE NW LATE IN THE DAY. THIS 
FEATURE MAY TRIGGER ADDITIONAL ISOLATED-SCATTERED CONVECTION TUESDAY 
EVENING ACROSS THE NW PIEDMONT...AND OVERNIGHT TUESDAY INTO EARLY 
WEDNESDAY OVER THE REMAINDER OF CENTRAL NC. WHILE FORCING IS BETTER 
COMPARED TO THE PAST FEW DAYS...LIFT IS STILL CONSIDERED WEAK-
MARGINAL AT BEST. THUS WILL LIMIT POPS TO NO HIGHER THAN LOW CHANCE.

ANOTHER HOT DAY IN STORE FOR THE REGION. AFTERNOON THICKNESSES WILL 
REMAIN 20-25M ABOVE NORMAL...SUPPORTIVE OF HIGH TEMPS IN THE LOW-MID 
90S UNDER FULL SUN CONDITIONS. WHEN THE HUMIDITY IS FACTORED 
IN...HEAT INDEX VALUES NEAR 100-104 WILL BE COMMON WITH THE HIGHEST 
H.I.VALUES IN THE SOUTHERN COASTAL PLAIN AND SANDHILLS. MIN TEMPS 
TUESDAY NIGHT GENERALLY IN THE LOWER 70S. -WSS

FOR WED/WED NIGHT: THE WEAK SURFACE REFLECTION THAT REMAINS FROM THE 
COLD FRONT APPROACHING CENTRAL NC WILL BECOME EVEN MORE WASHED OUT 
AS IT SHIFTS INTO THE LEE TROUGH OVER CENTRAL NC. MODELS SHOW A VERY 
WEAK VORTICITY LOBE ASSOCIATED WITH THIS FRONT PUSHING ESE THROUGH 
NC EARLY WED... AND ITS APPROACH ALONG WITH LINGERING STRONG LOW 
LEVEL MOISTURE TRANSPORT OVER ERN NC SHOULD SUPPORT AN AREA OF 
ATYPICAL MORNING SHOWERS/STORMS OVER THE ERN AND ESPECIALLY SE CWA 
WED MORNING. THE DEPARTURE AND DAMPENING OF THE MEAN MID LEVEL 
TROUGH WELL TO OUR NE WILL RESULT IN MODEST RISING HEIGHTS (15-25 M) 
WITHIN THE FLAT (W-E ORIENTED) MID LEVEL RIDGE ACROSS NC THROUGH WED 
NIGHT. THE LATEST NAM RUN IS CONSISTENT WITH PREVIOUS RUNS IN 
BRINGING LOWER PW (UNDER 1.5") INTO MUCH OF THE CWA FROM THE NW WITH 
A BIT STRONGER 850-700 MB NW WIND AS COMPARED TO THE GFS... WHICH 
KEEPS PW VALUES UP TO 1.7-1.9". GIVEN THE FACT THAT THE MID LEVEL 
TROUGH WILL BE DAMPENING WITH LITTLE REASON TO SUPPORT A STRONG PUSH 
OF DRY AIR PAST THE MOUNTAINS... THE GFS'S MORE SUBDUED TROUGH 
INFLUENCE APPEARS MORE LIKELY... BASED ON THE PERSISTENCE OF THE 
STRONG RIDGE. MODERATE INSTABILITY IS EXPECTED OVER ALL BUT PERHAPS 
THE FAR NW... WITH THE GFS SHOWING MUCAPE PEAKING AT 1000-2500 J/KG. 
WILL STAY CLOSE TO THE GFS/ECMWF SOLUTION WITH SCATTERED AFTERNOON 
THROUGH EVENING STORMS... WITH BEST COVERAGE ACROSS THE SOUTHERN CWA 
AND ALONG/EAST OF THE PERSISTENT LEE TROUGH... AS WELL AS ALONG THE 
INLAND-TRACKING SEA BREEZE. WITH ABOVE-NORMAL PW AND WEAK MID LEVEL 
FLOW... SLOW-MOVERS AND HEAVY-RAINERS ARE POSSIBLE. WITH THICKNESSES 
A TAD LOWER THAN TUE BUT REMAINING 12-20 M ABOVE NORMAL... EXPECT 
WARM AND STICKY HIGHS OF 91-95... DESPITE A GOOD CHANCE OF DEBRIS 
CLOUD COVER THROUGH THE DAY. CONVECTION CHANCES SHOULD RECEDE WED 
NIGHT BUT THE GFS INDICATES PLENTY OF ELEVATED BUOYANCY POTENTIAL 
OVERNIGHT... INCLUDING MLCAPE OF 500-1000 J/KG RESULTING FROM VERY 
WARM 960-920 MB TEMPS. WILL HOLD ONTO CHANCE POPS MAINLY SOUTH HALF 
OVERNIGHT. MUGGY LOWS IN THE LOW-MID 70S. -GIH

&&

.LONG TERM /THURSDAY THROUGH MONDAY/... 
AS OF 230 PM MONDAY... 

FOR THU/FRI: CONTINUED ABOVE-NORMAL WARMTH WITH ONLY MINOR CHANGES 
IN AIR MASS. AT THE SURFACE... THE WEAK LEE TROUGH HOLDS THROUGH 
CENTRAL NC... ALONG WITH A HUMID AND SOMEWHAT STAGNANT AIR MASS. A 
POSITIVELY TILTED TROUGH SHIFTS THROUGH THE PACIFIC NORTHWEST AND SW 
CANADA INTO THE DAKOTAS THU... RESULTING IN BUILDING HEIGHTS AND 
GRADUAL MID LEVEL WARMING OVER THE SOUTHEAST STATES. THIS POLAR 
STREAM TROUGH THEN SHIFTS INTO ERN CANADA... WHILE THE FLAT RIDGE 
HOLDS ACROSS NC. WITH PLENTY OF LOW LEVEL MOISTURE POOLING... 
ISOLATED TO SCATTERED STORMS FOCUSED ALONG A SEA BREEZE OR SOME 
OTHER SUBTLE BOUNDARY REMAIN A GOOD BET... DESPITE THE WARMING TEMPS 
ALOFT. WILL RETAIN AFTERNOON AND EVENING STORM CHANCES BOTH DAYS... 
WITH TEMPS HOLDING ABOUT A CATEGORY ABOVE NORMAL AS THICKNESSES STAY 
10-15 M ABOVE NORMAL. 

FOR SAT THROUGH MON: A PATTERN TRANSITION IS LIKELY NEXT WEEKEND. 
THE INITIAL MID LEVEL TROUGH CONTINUES HEADING EASTWARD OVER ERN 
CANADA EARLY SAT... HOWEVER A SLUG OF STRONG VORTICITY EMANATING 
FROM A STRONG COLD VORTEX OVER THE BEAUFORT SEA WILL PUSH EASTWARD 
CLOSE ON ITS HEELS... TAKING A COLD FRONT TO NEW ENGLAND AND THE OH 
VALLEY BY EARLY SAT. THE RESULTING TROUGH OVER ERN NOAM SUNDAY 
SHOULD HELP PUSH THE FRONT SOUTHWARD INTO NC... AFTER WHICH TIME IT 
IS APT TO LAY WEST/EAST AND STALL OVER THE CAROLINAS FOR LATE SUN 
THROUGH MON. THE GFS HAS A STRONGER/FASTER TIME FRAME THAN THE 
ECMWF... WITH THE FORMER MODEL SOLUTION TAKING THICKNESSES MUCH 
COLDER... UP TO 25 M BELOW NORMAL AS OPPOSED TO THE ECMWF WHICH IS 
BARELY 5 M BELOW NORMAL. TOUGH TO RESOLVE SUCH DIFFERENCES BUT GIVEN 
THE STRENGTH OF THE SRN CONUS RIDGE... AND THE FAR-NORTH TRACK OF 
THE POLAR LOW... I REMAIN SKEPTICAL ABOUT A STRONG COLD FRONTAL 
PASSAGE THROUGH NC. WILL STAY ON THE CONSERVATIVE SIDE OF THE TEMP 
TREND... WITH HIGHS/LOWS INITIALLY AROUND 90/AROUND 70 SAT... 
SLIPPING TO LOW-MID 80S/UPPER 60S BY MON. PRECIP CHANCES AND 
PATTERNS ARE LIKELY TO CHANGE LITTLE THROUGH SUN... PERHAPS 
INCREASING IN COVERAGE AS THE FRONT APPROACHES WITH FALLING HEIGHTS 
ALOFT... STRENGTHENING (YET STILL SOMEWHAT WEAK) MID LEVEL FLOW... 
AND A PERSISTENT CONFLUENT INFLUX OF GULF AND ATLANTIC MOISTURE IN 
THE LOW LEVELS. WILL MAINTAIN SCATTERED SHOWERS AND STORMS FOCUSED 
ON -- BUT NOT RESTRICTED TO -- AFTERNOON AND EVENING HOURS. WILL 
KEEP A CLIMO CHANCE POP ON MON... WITH LOWER THAN USUAL CONFIDENCE 
AS CONVECTION WILL GREATLY DEPEND ON WHETHER THE FRONT HOLDS UP 
ACROSS NC OR SHIFTS TO OUR SOUTH. -GIH

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/... 
AS OF 140 AM TUESDAY... 

VFR CONDITIONS CURRENTLY OBSERVED ACROSS CENTRAL NC.  EXPECT A FEW 
AREAS OF STRATUS WILL BE POSSIBLE THIS MORNING BETWEEN 09Z AND 
12Z...MAINLY FROM KFAY NORTH TO KRWI.  HOWEVER...BASED ON NEAR TERM 
GUIDANCE...CONFIDENCE IS INCREASING THAT THE AREAL COVERAGE OF 
STRATUS WILL BE RATHER LIMITED.  LATER TODAY...ISOLATED STORMS WILL 
BE POSSIBLE...WITH A BETTER CHANCE THIS EVENING AND INTO THE 
OVERNIGHT HOURS AS A WEAK COLD FRONT SLIPS INTO NC FROM THE NORTH.  
AT THIS TIME... CONFIDENCE IN THE TIMING OF STORMS IS TOO LOW FOR 
MENTION IN THE TAFS BUT INCREASE WITH SUBSEQUENT TAF ISSUANCES.

OUTLOOK...TYPICAL SUMMERTIME CONDITIONS ARE EXPECTED TO PERSIST 
THROUGH THE PERIOD...FEATURING DIURNAL CONVECTION EACH 
AFTERNOON/EVENING AND PATCHY FOG/LOW CLOUDS DURING THE PRE-DAWN 
MORNING HOURS. 

&&

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

&& 

$$

SYNOPSIS...WSS 
NEAR TERM...BSD/WSS 
SHORT TERM...WSS/HARTFIELD 
LONG TERM...HARTFIELD 
AVIATION...KRD/BLS



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