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FXUS62 KRAH 150338
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1037 PM EST FRI NOV 14 2008

.SYNOPSIS...
A WARM FRONT WILL PUSH NORTHWARD THROUGH THE AREA TONIGHT. A
STRONG COLD FRONT WILL APPROACH FROM THE EAST TONIGHT AND CROSS THE 
AREA SATURDAY AFTERNOON. SHOWERS AND THUNDERSTORMS WILL REMAIN 
NUMEROUS TO WIDESPREAD ACROSS THE REGION UNTIL THE FRONTAL PASSAGE 
ON SATURDAY. MUCH COLDER AIR WILL FILTER INTO CENTRAL NORTH CAROLINA 
BEHIND THE FRONT. 

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 1030 PM FRIDAY...

THE COASTAL FRONT HAS REALLY STRUGGLED TO MOVE INLAND THIS EVENING 
WITH THE RESIDUAL WEDGE BEING MUCH MORE STUBBORN THAN THE MODELS 
HAVE ADVERTISED (A KNOWN MODEL BIAS). AS OF 10 PM...THE FRONT IS 
STILL LOCATED TO THE SOUTH OF THE CWA AND IS ROUGHLY POSITIONED JUST 
NORTHWEST OF NEW BERN...JACKSONVILLE...AND WHITEVILLE BASED ON SFC 
THETA-E AND SFC LI ANALYSIS. ACROSS CENTRAL NORTH CAROLINA... 
TEMPERATURES HAVE BEEN HOLDING IN THE UPPER 50S IN THE TRIAD TO 
LOWER 60S ELSEWHERE WITH DEWPOINTS A DEGREE OR TWO LOWER. 

AFTER A GENERAL BREAK IN PRECIPITATION OVER THE PAST FEW 
HOURS...HEAVIER SHOWERS AND ISOLATED THUNDERSTORMS ARE BEGINNING TO 
MOVE BACK IN FROM THE SOUTHWEST ACROSS SOUTH CAROLINA. THIS 
CONVECTION IS BEING GENERATED BY A DEAMPLIFYING SHORTWAVE AND 
ASSOCIATED 120 KT UPPER LEVEL JET EJECTING NORTHEAST OUT OF THE 
NORTHERN GULF OF MEXICO AND A AHEAD OF THE DEEPENING TROUGH OVER THE 
CENTRAL STATES. THE THUNDERSTORM ACTIVITY IS ALL ELEVATED AS IT IS 
LOCATED ON THE COOL SIDE OF THE BOUNDARY IN A STABLE SFC LAYER...AS 
CAN BE SEEN ON THE 00Z GSO AND FFC SOUNDINGS. WEAK ELEVATED 
INSTABILITY IS PRESENT AROUND 850 MB AS MID LEVEL LAPSE RATES BEGIN 
TO STEEPEN AHEAD OF THE SHORTWAVE. 

EXPECT PRECIPITATION TO INCREASE ACROSS THE REGION OVER THE NEXT 
SEVERAL HOURS AS THE SHORTWAVE ENERGY CONTINUES TO QUICKLY MOVE 
NORTHEAST. FOR THE NEXT SEVERAL HOURS...ANY THUNDERSTORM ACTIVITY 
WILL REMAIN ELEVATED OVER THE MAJORITY OF CENTRAL NORTH CAROLINA.
DEEP LAYER SHEAR OF 45-55 KT IS SUPPORTIVE OF ELEVATED SUPERCELLS 
BUT NO DAMAGING WIND OR TORNADO THREAT WILL OCCUR IN THE STABLE 
LAYER. LARGE HAIL WOULD BE A THREAT...BUT THAT TOO WILL BE LIMITED 
BASED ON THE DEEP MOIST ADIABATIC PROFILES. 

THE THREAT OF SFC BASED STORMS INCREASE DURING THE EARLY MORNING 
HOURS AS THE COASTAL FRONT CONTINUES TO SLOWLY PUSH INLAND IN 
RESPONSE TO THE STRENGTHENING SOUTHERLY FLOW ASSOCIATED WITH THE 
INCREASING PRESSURE GRADIENT. SFC BASED INSTABILITY OF 500-1000 J/KG 
SHOULD SPREAD INLAND...CREATING A ENVIRONMENT MORE FAVORABLE FOR A 
FEW STRONG TO SEVERE STORMS...ESPECIALLY IN CLOSE PROXIMITY TO THE 
BOUNDARY. DAMAGING WINDS WILL BE THE MAIN THREAT AS THE LOW LEVEL 
JET INTENSIFIES TO NEAR 50 KT. A BRIEF TORNADO CANNOT BE TOTALLY 
RULED OUT ALONG THE WARM FRONT...BUT THE GENERALLY VEERED NATURE OF 
THE SFC FLOW (WINDS MORE S-SW POST FRONT) WILL LIMIT THE OVERALL 
POTENTIAL. BEST SEVERE POTENTIAL SHOULD BE IN THE SANDHILLS AND 
COASTAL PLAIN THROUGH SUNRISE. TEMPERATURES WHICH HAVE BEEN HOLDING 
STEADY WILL GRADUALLY RISE THROUGH DAYBREAK...WITH TEMPS NEAR 70 
LIKELY IN THE SOUTHEAST COASTAL PLAIN. 

THE WARM SECTOR SPREADS ACROSS MUCH OF THE AREA BY 12Z AS THE STRONG 
COLD FRONT BEGINS TO MARCH IN FROM THE WEST. THE FRONT LOOKS TO 
CLEAR THE WESTERN PIEDMONT BY LATE MORNING AND THE COASTAL PLAIN BY 
LATE AFTERNOON. IMPRESSIVE DYNAMICS ASSOCIATED WITH THE HIGHLY 
AMPLIFIED MID AND UPPER LEVEL TROUGH SHOULD SERVE TO FORCE A 
CONVECTIVE LINE OF STORMS ALONG THE FRONT. DAMAGING STRAIGHT LINE 
WINDS APPEAR TO BE THE BIGGEST THREAT DUE TO THE OVERWHELMING LINEAR 
FORCING ALONG THE FRONT. HOWEVER...0-1KM SHEAR IS STILL SUFFICIENT 
TO MAINTAIN THE POSSIBILITY OF AN EMBEDDED ISOLATED TORNADO. THE 
BEST THREAT APPEARS TO BE OVER CENTRAL AND EASTERN PORTIONS OF THE 
AREA WHERE THE GREATEST SFC BASED INSTABILITY SHOULD BE LOCATED DUE
TO THE LATER TIMING OF THE FRONT AND HIGHER CHANCES OF 
DESTABILIZATION.

HIGH TEMPS SOMEWHAT TRICKY BASED ON FRONTAL TIMING. HAVE TRIMMED 
BACK TEMPS IN THE FAR NW PIEDMONT DUE TO THE LATER EROSION OF THE 
WEDGE. HIGHS 63 W TO 74 E. TEMPS/DEWPOINTS BEGIN TO QUICKLY DROP 
POST FRONT AS COLD AIR ADVECTION KICKS IN. 
  
&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 245 PM FRIDAY...

SATURDAY NIGHT:
A POWERFUL NORTHERN STREAM TROUGH ALOFT -- NOW AMPLIFYING IN 
NORTHWESTERLY FLOW ALOFT OVER THE CENTRAL US -- WILL CROSS CENTRAL 
NC SATURDAY NIGHT. MODELS CONTINUE TO PROG STRONG Q-VECTOR 
CONVERGENCE (OWING TO DCVA AHEAD OF THE TROUGH) AND FGEN IN THE MID 
AND UPPER LEVELS. HOWEVER... THE ASSOCIATED ASCENT WILL HAVE NO 
MOISTURE TO WORK WITH AS PRECIPITABLE WATERS CRASH TO ONE HALF INCH 
OR LESS OVERNIGHT. STRONG LOW LEVEL CAA SENDS LOW LEVEL THICKNESSES 
TO A FORECAST MINIMUM IN THE 1305 TO 1315 METER RANGE BY 12Z 
SUNDAY... SOME 80 METERS LOWER THAN SATURDAY. THE COLD ADVECTION 
SHOULD KEEP A STEADY NW BREEZE (~10 MPH WITH FEW GUSTS UP TO 20 
POSSIBLE) UP OVERNIGHT. LOW TEMPERATURES BEHIND THE FRONT OVER THE 
NORTHERN PLAINS THIS MORNING WITH SIMILAR THICKNESSES YIELDED LOWS 
IN THE MIDDLE TO UPPER 30S. TAKING INTO ACCOUNT SOME AIRMASS 
MODIFICATION... LOWS 40 NW TO 47 SE SEEM REASONABLE... AND IS IN 
LINE WITH THE SIMILAR 12Z MAV/MET MOS. 

SUNDAY AND SUNDAY NIGHT: SURFACE RIDGING WILL EXPAND INTO OUR 
REGION FROM THE SOUTHWEST... AS HEIGHTS ALOFT RISE BEHIND THE 
DEPARTING UPPER TROUGH. LOW LEVEL THICKNESSES ARE FORECAST TO BE 
ABOUT 30 METERS/10 DEGREES BELOW AVERAGE... AND THIS EQUATES TO 
HIGHS 50 OF 55 DEGREES. A NW'RLY DOWNSLOPE WIND OF 15 TO 30 KTS AT 
H85 AND THE INDICATION OF DRY ADIABATIC MIXING THROUGH H85 ON 
FORECAST SOUNDINGS... YIELDS HIGHS A COUPLE OF DEGREES WARMER... 
GENERALLY 53 TO 57 UNDER MOSTLY SUNNY SKIES. GIVEN THE RELATIVELY 
DEEP MIXING AND STIFF H85 WINDS... A NORTHWESTERLY BREEZE OF 10 TO 
15 MPH COULD GUST TO AROUND 25 MPH DURING THE AFTERNOON. SIMILAR LOW 
LEVEL THICKNESSES TO SUNDAY MORNING BUT A LIGHT TO CALM WIND AND 
CONTINUED CLEAR SKIES BENEATH THE RIDGE AXIS CENTERED OVER THE DEEP 
SOUTH SUGGESTS LOWS 30 TO 35 DEGREES.    

MONDAY: INCREASING LOWER TO MID LEVEL WAA AHEAD OF ANOTHER 
AMPLIFYING TROUGH IN NW'RLY FLOW ALOFT WILL LIKELY SPREAD INCREASING 
MID LEVEL MOISTURE ACROSS OUR REGION MONDAY. SOUTHWESTERLY FLOW 
AHEAD OF A SURFACE COLD FRONT ATTENDANT THE UPPER TROUGH SUGGESTS 
HIGHS SHOULD BE ABOUT A CATEGORY WARMER THAN THOSE OF SUNDAY... 
ABOUT 55 TO 60 DEGREES. 

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 245 PM FRIDAY...

AT KGSO...KRDU...AND KFAY...ONE HAS TO GO BACK TO MARCH 30 FOR THE 
LAST DAY WHEN HIGHS DID NOT GET OUT OF THE 40S...AND TUESDAY IS A 
DAY THERE STANDS A GOOD CHANCE OF THIS OCCURRING IN CENTRAL 
NORTH CAROLINA AS THICKNESSES FALL COINCIDENT WITH A LONG-WAVE 
TROUGH MOVING ACROSS THE STATE AND THE PRESENCE OF NORTHERLY
SURFACE FLOW. BOTH THE GFS AND THE ECMWF ARE CLOSE IN THE TIMING
OF THE TROUGH AND AT LEAST MODERATE...MAINLY CHANNELED VORTICITY
MOVING ACROSS THE STATE FROM LATE MONDAY NIGHT THROUGH TUESDAY. IN
GENERAL...THE GUIDANCE KEEPS THE FOCUS OF MID-LEVEL MOISTURE TO
THE NORTH OF CENTRAL NORTH CAROLINA...BUT JUST TO THE NORTH.
THICKNESSES ARE OBVIOUSLY COLD...AND THOUGH THE OVERALL AIR MASS
WILL BE DRY AND ANY PRECIPITATION LIKELY WOULD HAVE A VERY HARD
TIME MEASURING...WILL HAVE TO OBSERVE GUIDANCE TRENDS OVER THE
NEXT COUPLE OF DAYS OR SO TO ASSESS THE DEGREE OF MOISTURE ALOFT
AND THE STRENGTH OF MID-LEVEL SUPPORT. CURRENTLY...BOTH THE GFS
AND THE ECMWF ARE FOCUSING ON AVAILABLE MOISTURE PRIMARILY IN A
NARROW LAYER AROUND 700MB.

HEIGHTS BEGIN TO RISE QUICKLY LATE TUESDAY INTO WEDNESDAY. HOWEVER...
LIGHT WINDS EXPECTED AT THE SURFACE WITH FEW CLOUDS ANTICIPATED AT 
THIS TIME SHOULD ALLOW OVERNIGHT LOWS TO FALL WELL INTO THE 20S ON 
AVERAGE ACROSS CENTRAL NORTH CAROLINA TUESDAY NIGHT INTO WEDNESDAY 
MORNING. TIMING OF SURFACE AND UPPER-LEVEL FEATURES THEN BEGINS TO 
DIVERGE SOME LATE NEXT WEEK WITH THE 06Z GFS FASTER WITH THE 
APPROACH AND PASSAGE OF A SURFACE COLD FRONT AND UPPER TROUGH 
FRIDAY...WHILE THE ECMWF IS LATER...LATE FRIDAY INTO EARLY SATURDAY. 
THE 12Z GFS HAS TRENDED SLOWER...MORE TOWARD THE ECMWF...THOUGH ONCE 
AGAIN MOISTURE IS LIMITED THROUGHOUT THE OVERALL AIR MASS. WILL 
CONTINUE TO KEEP THE FORECAST DRY FOR NOW ESPECIALLY OUT TO THE 
SEVENTH DAY...THOUGH THICKNESSES ARE WARM. HIGHS SHOULD BE IN THE 
50S FOR THURSDAY AND FRIDAY. BEYOND THIS PERIOD...THE LATEST GFS
HAS TRENDED TO A LESS AMPLIFIED SOLUTION WITH THE UPPER TROUGH IN
THE EASTERN CONUS WITH CORRESPONDINGLY HIGHER THICKNESSES AND
HEIGHTS. WHILE STILL ANTICIPATED TO BE BELOW NORMAL...TEMPERATURES
INTO NEXT WEEKEND MAY NOT BE QUITE AS COOL AS THOSE EXPECTED EARLY
IN THIS PART OF THE FORECAST.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... 
AS OF 700 PM FRIDAY...

A WARM FRONT OVER COASTAL NC/SC WILL LIFT NORTH THROUGH CENTRAL NC 
OVERNIGHT. THIS WILL BE IN RESPONSE TO THE APPROACHING MID LEVEL 
SYSTEM CURRENTLY OVER THE LOWER MISSISSIPPI VALLEY REGION. PATCHY 
RAIN AND SHOWERS WILL BECOME WIDESPREAD SHOWERS AND ISOLATED 
THUNDERSTORMS OVERNIGHT. LIFR CIGS WILL PERSIST MOST AREAS THROUGH 
THE NIGHT. MOSTLY MVFR VSBYS EARLY WILL LOWER INTO THE IFR TO LIFR 
CATEGORIES LATE TONIGHT. WINDS WILL INCREASE TO AROUND 10-15KT FROM 
THE SOUTH AS THE WARM FRONT PUSHES THROUGH. GUSTS TO 25-30KT WILL BE 
LIKELY LATER TONIGHT. 

FOR SATURDAY... WIDESPREAD RAIN AND SHOWERS EARLY WILL TAPER OFF 
LATE MORNING INTO THE EARLY AFTERNOON. THIS WILL BE FOLLOWED BY 
ANOTHER BAND OF SHOWERS AND SCATTERED THUNDERSTORMS... WITH 
POTENTIALLY GUSTY WINDS IN EXCESS OF 40KT IN THE AFTERNOON. THIS 
BAND OF CONVECTION IN THE AFTERNOON WILL BE ASSOCIATED WITH A COLD 
FRONTAL PASSAGE. IFR TO MVFR CIGS EXPECTED THROUGHOUT THE DAY... 
WITH MVFR VSBYS... REDUCING AT TIMES INTO THE LIFR CATEGORY WITH 
HEAVY RAIN SHOWERS. 

CIGS WILL RISE ABRUPTLY (MVFR THEN VFR) AFTER THE COLD FRONT PASSES 
SATURDAY AFTERNOON WEST... AND IN THE EAST LATE IN THE DAY. WINDS 
WILL SHIFT TO THE WEST AT 15-25KT. 

VFR CONDITIONS EXPECTED SUNDAY THROUGH MONDAY. 

&&

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

&&

$$
SYNOPSIS...JFB
NEAR TERM...JFB
SHORT TERM...MWS
LONG TERM...DJF
AVIATION...BADGETT