Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 241757
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
157 PM EDT TUE MAR 24 2015

.SYNOPSIS...SURFACE HIGH PRESSURE WILL EXTEND OVER THE AREA THROUGH
TONIGHT. THE HIGH WILL SHIFT OFFSHORE ON WEDNESDAY...ALLOWING A WARM
FRONT TO LIFT NORTH ACROSS THE AREA WEDNESDAY NIGHT. A COLD FRONT
WILL APPROACH FROM THE WEST ON THURSDAY...AND WILL CROSS THE AREA
THURSDAY NIGHT AND INTO FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM TUESDAY...

TODAY: HIGH PRESSURE OVER SOUTHERN ONTARIO WILL EXTEND DOWN THE
EASTERN SEABOARD AND INTO THE CAROLINAS TODAY WHILE FLOW REMAINS
ZONAL ALOFT. EARLIER LOW STRATUS HAS BURNED OFF IN MOST AREAS WITH
THE EXCEPTION OF THE NORTHWEST PIEDMONT WHERE MVFR CEILINGS ARE
STILL ONGOING. THESE CLOUDS ARE DRIFTING EASTWARD BUT MOST LIKELY AT
HIGHER BASES THAN MVFR LEVELS SO WILL HAVE SOME BROKEN TO OVERCAST
SKIES COMING INTO THE TRIANGLE LATER THIS MORNING INTO EARLY
AFTERNOON. IN GENERAL EXPECT MUCH MORE CLOUD COVER TO THE NORTH AS
OPPOSED TO THE SOUTH AND THEREFORE MAY HAVE SOME DIFFERENTIAL
HEATING BEGIN TO OCCUR. AS A RESULT TEMPERATURES IN THE SOUTH MAY
REACH HIGHER LEVELS THAN THOSE IN THE NORTH. ANOTHER FACTOR IN THIS
IS WIND DIRECTION AS NORTHEASTERLY FLOW STILL PERSISTS IN THE
NORTHEAST AND MORE EASTERLY OR SOUTHEASTERLY FLOW IN THE SOUTH AND
WEST. THEREFORE THE TEMPERATURE DISTRIBUTION TODAY WILL HAVE LOWEST
TEMPS IN THE NORTHEAST WITH MID 50S TO LOW 60S EXPECTED. IN THE
NORTHWEST PIEDMONT EXPECT MAINLY LOWER 60S AS MORE WARM AIR ADVECTION
OCCURS HERE BUT CLOUD COVER PUTS A DAMPER ON WARMING. FINALLY IN THE
SOUTH EXPECT THE HIGHEST TEMPERATURES IN THE UPPER 60S TO NEAR 70
DEGREES AS LACK OF CLOUD COVER ALLOWS FOR MORE INSOLATION. NO
PRECIPITATION IS EXPECTED TODAY. -ELLIS

TONIGHT: LEAD SHORTWAVE TROUGH AND ASSOCIATED SFC LOW PRESSURE OVER
THE CENTRAL PLAINS/MID MS VALLEY WILL LIFT EAST-NORTHEASTWARD
THROUGH THE OHIO VALLEY TONIGHT...REACHING THE LOWER GREAT LAKES
WEDNESDAY MORNING. WHILE WE WILL ONLY RECEIVE A GLANCING SHOT...
STRENGTHENING SOUTHWESTERLY LOW LEVEL JET/LOW LEVEL WARM AIR
ADVECTION PATTERN ACROSS THE TN VALLEY/MID-ATLANTIC STATES WILL
SUPPORT SLIGHT CHANCE OF RAIN/DRIZZLE LATE THIS EVENING THROUGH THE
OVERNIGHT HOURS ACROSS THE FAR NW/NORTHERN ZONES. LOWS TONIGHT
RANGING FROM UPPER 30S/NEAR 40 NORTH TO UPPER 40S/NEAR 50. -CBL

&&


.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 350 AM TUESDAY...

STRONG 1030MB SURFACE HIGH PRESSURE WILL SHIFT OFF THE MID-ATLANTIC
COAST EARLY WEDNESDAY. HOWEVER...ANY PRECIP THAT FALLS INTO THE
RESIDUAL DRY COOL AT THE SURFACE LATE TONIGHT-WEDNESDAY MORNING WILL
HELP TO ESTABLISH IN-SITU WEDGING ACROSS THE WESTERN/CENTRAL
PIEDMONT WITH CONTINUED MOIST UPGLIDE SUPPORTING OVERCAST LOW CLOUDS
THROUGH THE AFTERNOON. HIGHS RANGING FROM UPPER 50S NW TO LOWER 70S
ACROSS THE SOUTH/SOUTHEAST.

A SECONDARY AMPLIFYING TROUGH WILL DIG SEWD INTO THE CENTRAL PLAINS
WEDNESDAY AND WEDNESDAY NIGHT. DEEPENING SWLY FLOW IN ADVANCE OF THE
AMPLIFYING TROUGH WILL HELP TO LIFT A WARM FRONT THROUGH THE AREA
WEDNESDAY NIGHT. ASSOCIATED STRONG WAA WILL LEAD TO ELEVATED
INSTABILITY OVERNIGHT(MUCAPE 400-600 J/KG)WHICH WILL SUPPORT HIGH TO
LIKELY POPS ACROSS THE AREA WITH SOME ISOLATED THUNDER POSSIBLE. NON-
DIURNAL TEMPERATURES OVERNIGHT...WARMING ACROSS THE PIEDMONT AS THE
WEDGE ERODES...WHILE HOLDING STEADY ACROSS THE SOUTH. LOWS RANGING
FROM MID 50S NORTH(EVENING)TO LOWER 60S SOUTH.


&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 330 AM TUESDAY...

LOOKING AT TEMPS WAY UP IN THE 70S TO LOWER 80S ON THURSDAY WITH
DEEP SOUTHWEST WARM AIR ADVECTION AHEAD OF AN APPROACHING COLD
FRONT. INSTABILITY WILL BE QUITE HIGH...WITH MID LEVEL LAPSE RATES
>6C AND FORECAST CAPES OF ~1K JOULES. SHOWER COVERAGE SHOULD BE
DECENT...BUT NO GOOD TRIGGERING MECHANISM ALONG WITH UNIDIRECTIONAL
FLOW AND WEAK UPPER DIFFLUENCE MAKE THUNDER A LITTLE LESS
LIKELY...WILL HAVE HIGH CHANCE POPS AND SLIGHT CHANCES FOR THUNDER
DURING THE FAVORED MAX HEATING INTO EARLY EVENING TIME FRAME. WILL
MAINTAIN CHANCES OF ANAFRONTAL SHOWERS THROUGH THE NIGHT WHICH WILL
ACCOMPANY THE SURGE OF COLDER AIR BEHIND THE SURFACE FRONT WHICH
MOVES THROUGH AROUND MIDNIGHT. COLD AIR ADVECTION AND AT LEAST SOME
CLEARING WILL BE UNDERWAY IN THE WEST BY SUNRISE WITH MINS IN THE
MID 40S NORTHWEST TO LOWER 50S SOUTHEAST.

INITIAL SURGE OF COLD AIR ADVECTION FRIDAY WILL BE AUGMENTED BY AN
ADDITIONAL STRONG SHORT WAVE IN THE MID LEVEL FLOW WHICH WILL MOVE
ACROSS THE AREA EARLY FRIDAY NIGHT. THE SHORT WAVE LOOKS QUITE
VIGOROUS AND EXPECT SHOWERS OUT OF THE STRATOCUMULUS ACCOMPANYING
THE WAVE...MAINLY THROUGH AROUND MIDNIGHT. THE AMPLIFIED LONG WAVE
TROF OVER THE EASTERN CONUS WILL PIVOT ACROSS THE AREA AS THE SHORT
WAVE LIFTS OUT LATER FRIDAY NIGHT. LOW LEVEL THICKNESS VALUES WILL
CORRESPONDINGLY CRASH AND WITH MOSTLY CLEAR SKIES BY SATURDAY
MORNING...MINS WILL BE MID TO UPPER 30S TO KICK OFF THE WEEKEND.

COOL AIRMASS WILL BE IN PLACE FOR THE REMAINDER OF THE WEEKEND WITH
SATURDAY AS OUR COOLEST DAY...WITH HIGHS IN THE NORTHWEST IN THE
UPPER 40S...WITH MOSTLY LOWER 50S ELSEWHERE. SURFACE HIGH PRESSURE
OVERHEAD WILL PRODUCE NEAR IDEAL RADIATIONAL CONDITIONS SATURDAY
NIGHT WITH CLEAR SKIES AND CALM WINDS...AND MORNING LOWS SUNDAY
MORNING WILL EDGE A DEGREE OR TWO BELOW FREEZING OVER ALL BUT THE
SOUTHEAST. STRONG SUN AND BUILDING HEIGHTS ALOFT WILL ALLOW RECOVERY
TO COMMENCE SUNDAY...WITH HIGHS IN THE UPPER 50S TO LOWER
60S...WARMING TO MOSTLY MID 60S ON MONDAY.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 200 PM TUESDAY...

24 HOUR TAF PERIOD: VFR CONDITIONS INITIALLY WILL PERSIST FOR THE
AFTERNOON AND INTO THE EVENING BUT LATE EVENING EXPECT CEILINGS TO
START COMING DOWN STEADILY AND ALL SITES WILL REALIZE AT LEAST IFR
CONDITIONS OVERNIGHT TONIGHT WITH THE TRIAD SITES POSSIBLY GETTING
DOWN TO LIFR. RELATIVE HUMIDITY CROSS SECTIONS SHOW THAT ONCE
CEILINGS ARE DOWN THEY WILL PROBABLY STAY DOWN THROUGH THE TAF
PERIOD...EXCEPT IN THE SOUTH AND EAST WHERE THEY MAY IMPROVE A
LITTLE BUT NOT TO VFR LEVELS. THE TRIAD SITES WILL CERTAINLY BE THE
MOST PESSIMISTIC AS COLD AIR DAMMING SCENARIO SETS IN. WINDS WILL BE
PREDOMINANTLY EASTERLY BUT FAIRLY LIGHT AT AROUND 5 KTS. A SLIGHT
CHANCE OF SOME DRIZZLE ACROSS THE NORTH WILL BE POSSIBLE TONIGHT.

LONG TERM: CONDITIONS MAY IMPROVE BRIEFLY WEDNESDAY EVENING BUT THEN
MORE FOG/LOW STRATUS IS EXPECTED THURSDAY MORNING WITH INCREASED
RAIN CHANCES. THURSDAY AFTERNOON/EVENING WILL FEATURE CHANCES FOR
CONVECTION IN THE WARM SECTOR AHEAD OF A COLD FRONT WHICH WILL MOVE
THROUGH ON FRIDAY. CONDITIONS SHOULD RETURN TO VFR LEVELS FOR THE
WEEKEND.

&&

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

&&

$$

SYNOPSIS...CBL
NEAR TERM...ELLIS/CBL
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...ELLIS


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