Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 260743
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
343 AM EDT THU MAR 26 2015

.SYNOPSIS...A COLD FRONT WILL APPROACH THE MOUNTAINS FROM THE WEST
THIS AFTERNOON AND EVENING...THEN TRACK SOUTHEAST THROUGH CENTRAL
NORTH CAROLINA LATE TONIGHT. THE COLD FRONT WILL BRIEFLY STALL
OFFSHORE THE CAROLINA COAST ON FRIDAY AS A POTENT UPPER LEVEL
DISTURBANCE APPROACHES FROM THE WEST.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 325 AM THURSDAY...

TODAY: LOW-LEVEL MOISTURE ADVECTION VIA A 30-KT SOUTHERLY LLJ
BENEATH THE MODIFIED ELEVATED MIXED LAYER IN PLACE ACROSS THE REGION
THIS MORNING IS RESULTING IN NOCTURNAL DESTABILIZATION...WITH MUCAPE
ON THE ORDER OF 500-1000 J/KG (MUCAPE) OVER CENTRAL NC. GIVEN
FAVORABLE THERMODYNAMICS...LOW-LEVEL WARM ADVECTION AND SFC
CONVERGENCE IN VICINITY OF A QUASI-STATIONARY FRONT SEPARATING THE
WARM SECTOR (EAST) FROM RESIDUAL CAD WEDGE (WEST) NEAR THE HWY 1
CORRIDOR WILL BE SUFFICIENT FOR SCATTERED TO NUMEROUS SHOWERS AND
PERHAPS AN ISOLD THUNDERSTORM THROUGH SUNRISE...WITH ACTIVITY
SHIFTING INTO EAST/NE PORTIONS OF THE STATE BY MID/LATE MORNING AS
WARM ADVECTION SHIFTS DOWNSTREAM AND FLOW VEERS TO THE SOUTHWEST...
ADVECTING A DRIER LOW-LEVEL AIRMASS INTO CENTRAL NC. THIS...IN
ADDITION TO DEEPER VERTICAL MIXING (IN COMPARISON TO PRIOR DAYS) AND
THE PRESENCE OF A MODIFIED ELEVATED MIXED LAYER (7.0-7.5 C/KM H7-H5
LR) WILL RESULT IN A CAPPED THERMODYNAMIC ENVIRONMENT CHARACTERIZED
BY WEAK DIURNAL DESTABILIZATION AND ~50 J/KG OF CIN DURING PEAK
HEATING. ASIDE FROM THE POTENTIAL FOR A ROGUE SMALL AMPLITUDE WAVE
IN STRENGTHENING SW FLOW ALOFT...FORCING FOR ASCENT WILL OTHERWISE
BE DIFFICULT TO COME BY. WITH THE ABOVE IN MIND...WILL INDICATE A
DRY FORECAST THIS AFTERNOON...WITH THE EXCEPTION OF A SLIGHT CHANCE
OF A LOW-TOPPED SHOWER IN THE SE COASTAL PLAIN DURING THE LATE
AFTERNOON WHEN SFC WINDS BACK TO THE SOUTH IN ADVANCE OF AN
APPROACHING COLD FRONT...RESULTING IN WEAK LOW-LEVEL CONVERGENCE AND
RELATIVELY BETTER LOW-LEVEL MOISTURE ACROSS PORTIONS OF THE COASTAL
PLAIN. EXPECT HIGHS IN THE 70S...LOWER/MID 70S NW PIEDMONT AND UPPER
70S ALONG/EAST OF HWY 1.

TONIGHT: THE AFOREMENTIONED COLD FRONT WILL PROGRESS INTO CENTRAL NC
OVERNIGHT...THOUGH FORWARD PROGRESS WILL BEGIN TO SLOW AS STRONG
DPVA /HEIGHT FALLS/ ATTENDANT AN AMPLIFYING UPPER LEVEL TROUGH
APPROACHES FROM THE WEST. WITH SUFFICIENT MOISTURE AND STRONG DEEP-
LAYER FORCING...EXPECT WIDESPREAD RAIN TO DEVELOP AFTER MIDNIGHT...
PREDOMINATELY OF THE ANAFRONTAL /ELEVATED/ VARIETY...THOUGH A NARROW
LINE OF LOW-TOPPED SFC-BASED SHOWERS CANNOT BE RULED OUT ALONG THE
FRONT EAST OF HWY 1. LOW TEMPS WILL DEPEND ON A COMBINATION OF COLD
ADVECTION AND PRECIP /EVAP COOLING/...FALLING FROM THE LOWER/MID 60S
TO THE LOWER/MID 40S FROM WNW TO ESE AFTER MIDNIGHT...EXCEPT IN THE
FAR SOUTHEAST (I.E. FAY/CTZ/GSB) WHERE THE WARM SECTOR COULD PERSIST
INTACT THROUGH 12Z AND TEMPS WOULD HOVER AT OR NEAR 60F. -VINCENT

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 340 AM THURSDAY...

FRIDAY: EXPECT LINGERING ANAFRONTAL PRECIPITATION AND CHILLY
TEMPERATURES ON FRIDAY AS SOUTHWEST FLOW ALOFT /WARM ADVECTION/
PERSISTS ATOP A DEVELOPING POST-FRONTAL CAD WEDGE...IN ADVANCE OF AN
AMPLIFYING UPPER LEVEL TROUGH APPROACHING FROM THE WEST. EXPECT
CLOUDY CONDITIONS WITH RAIN PERSISTING THROUGH MUCH OF THE DAY...ESP
EAST OF HWY 1. AFTERNOON HIGHS ARE UNLIKELY TO EXCEED THE LOW/MID
40S...EXCEPT IN THE WESTERN PIEDMONT WHERE CLOUD COVER MAY BREAK
SEVERAL HRS PRIOR TO SUNSET AND A WARM-UP INTO THE UPPER 40S /NEAR
50F/ WOULD BE POSSIBLE. -VINCENT

FRIDAY NIGHT: TO BE POSTED SHORTLY.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 345 AM THURSDAY...

TO BE POSTED SHORTLY.

&&

.AVIATION /06Z THURSDAY THROUGH SUNDAY/...
AS OF 300 AM THURSDAY...

24-HR TAF PERIOD: IFR/LIFR CEILINGS AND SHOWERS WILL PREVAIL THIS
MORNING...THOUGH CONDITIONS WILL IMPROVE TO MVFR AND PERHAPS VFR
DURING THE AFTERNOON AS A SLIGHTLY DRIER LOW-LEVEL AIRMASS ADVECTS
INTO THE REGION AND A BREEZY SOUTHWEST FLOW DEVELOPS...BECOMING
SUSTAINED AT 10-15 KT WITH GUSTS TO 20-25 KT. IMPROVED CONDITIONS
WILL BE SHORT-LIVED...HOWEVER...AS A COLD FRONT PROGRESSES INTO THE
REGION TONIGHT. A WIND SHIFT TO THE NORTHWEST AT 10-15 KT (GUSTS TO
20 KT) ALONG WITH THE REDEVELOPMENT OF IFR/LIFR CEILINGS IS EXPECTED
IN THE WAKE OF THE FRONT BETWEEN 06-12Z FRI...WITH ONLY MARGINAL
IMPROVEMENT TO IFR BY THE END OF THE TAF PERIOD.

LOOKING AHEAD: IFR CEILINGS AND PRECIPITATION WILL GRADUALLY END
FROM WEST-EAST LATE FRI/FRI EVENING...AND VFR CONDITIONS MAY RETURN
FOR A PERIOD. HOWEVER...A POTENT UPPER LEVEL TROUGH CROSSING THE
REGION WILL LIKELY RESULT IN ANOTHER PERIOD OF MVFR/IFR CEILINGS AND
A CHANCE OF SHOWERS AT EASTERN TERMINALS AFTER 06Z SAT. VFR
CONDITIONS WILL PREVAIL THE REMAINDER OF THE WEEKEND AS HIGH
PRESSURE BUILDS TOWARD THE AREA FROM THE WEST. -VINCENT

&&

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

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT/MLM
LONG TERM...MLM
AVIATION...VINCENT


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