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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 181609
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1210 PM EDT TUE JUN 18 2013

.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTHWEST LATE TODAY...AND CROSS
THE REGION TONIGHT. HIGH PRESSURE WILL BUILD INTO CENTRAL NC FROM
THE NORTH WEDNESDAY THROUGH THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM TUESDAY...

VERY MOIST AIR MASS RESIDES OVER CENTRAL NC THIS MORNING AS AREA
SOUNDINGS AND SATELLITE BLENDED TOTAL PRECIP PRODUCT DEPICT PRECIP
WATER VALUES BETWEEN 1.75-2 INCHES. ALSO...WATER VAPOR IMAGERY
DEPICT A PAIR OF MID LEVEL VORTICES LIFTING E-NE ACROSS EASTERN TN
AND NORTHERN GA. THE LATER VORTEX PROJECTED TO LIFT NE INTO CENTRAL
NC LATE THIS AFTERNOON. PERIODS OF PARTIAL SUN WILL AID TO BOOST
SBCAPE AND ML CAPE INTO THE 1000-1500 J/KG RANGE...MAINLY OVER
SECTIONS OF THE SANDHILLS AND COASTAL PLAIN. IN THE PIEDMONT...THE
CLOUD COVER WILL LIKELY REMAIN TOO EXTENSIVE TO PERMIT MUCH
SUN...LEADING TO A SLIGHTLY MORE STABLE AIR MASS. THUS EXPECT SHOWER
AND THUNDERSTORM COVERAGE TO INCREASE FROM THE WEST-SW LATER THIS
AFTERNOON AND CONTINUE INTO THE EARLY EVENING HOURS.

DUE TO THE MOIST AIR MASS...THE SHOWERS AND STORMS WILL BE EFFICIENT
RAIN PRODUCERS. WILL NEED TO MONITOR SECTIONS OF THE SOUTHERN AND
WESTERN PIEDMONT WHERE LOCALLY HEAVY RAIN HAS OCCURRED SINCE EARLY
MONDAY AFTERNOON. NOT ANTICIPATING THE NEED FOR A FLASH FLOOD WATCH
AT THIS TIME BUT MAY NEED TO ISSUE A FEW URBAN/SMALL STREAM
ADVISORIES WITH THE STRONGER CELLS.

WHILE STORM PREDICTION CENTER HAS HIGHLIGHTED OUR REGION IN A
SLIGHT RISK THIS AFTERNOON FOR DAMAGING WINDS...I DO HAVE SOME
DOUBTS. BULK SHEAR PROJECTED TO BE 30KTS OR LESS WITH THE LOWER
VALUES EXPECTED ACROSS THE SOUTH. LACK OF DECENT LAPSE RATES AND A
VERY MOIST AIR THROUGH THE COLUMN WILL ALSO HINDER DAMAGING WIND
GUST POTENTIAL. WHILE AN ISOLATED WET MICROBURSTS A DEFINITE
PROBABILITY...SCATTERED-NUMEROUS OCCURRENCES OF STRONG-GUSTY WINDS
LOOKS UNLIKELY.

AFTERNOON TEMPS DEPENDENT ON AMOUNT (IF ANY) OF ANY PARTIAL SUN AND
EXTENT OF CONVECTION. PREVIOUS FORECAST OF LOWER 80S NW TO MID 80S
SE APPEAR ON TARGET. -WSS

TONIGHT: WHILE THERE MAY BE A LULL THIS EVENING AFTER THE AFTERNOON
AND EARLY EVENING CONVECTION...THE LEAD SURFACE BOUNDARY IS FORECAST
TO SETTLE SOUTHEASTWARD INTO CENTRAL NC ABOUT THE TIME THE SURFACE
WAVE OVER THE MID SOUTH TRACKS TOWARD INTO OUR REGION. THE PASSAGE
OF THE SURFACE WAVE - ONE SUPPORTED FROM ALOFT BY THE APPROACH OF A
NORTHERN STREAM SHORTWAVE TROUGH FROM THE UPPER MIDWEST THIS
MORNING - WILL ENCOURAGE RENEWED DEVELOPMENT OF AN AREA OF SHOWERS
AND ISOLATED STORMS OVER CENTRAL NC OVERNIGHT. LOWS...WITH MOSTLY
CLOUDY SKIES...IN THE MIDDLE 60S TO AROUND 70 DEGREES. TOTAL
RAINFALL AMOUNTS IN THE ONE TO TWO INCH RANGE WILL BE COMMON...
HIGHEST NORTH AND NORTHWEST...THOUGH AS WITH ANY CONVECTIVE
PRECIPITATION THERE WILL BE SOME AREAS THAT LIKELY RECEIVE
CONSIDERABLY LESS. -MWS

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 325 AM TUESDAY...

THE NORTHERN STREAM FRONT REFERENCED IN THE NEAR TERM DISCUSSION - A
FRONT LIKELY ENHANCED BY NE MARITIME FLOW FROM CHESAPEAKE BAY
REGION - WILL NOT DRIFT SOUTHWARD THROUGH CENTRAL NC UNTIL THE
AFTERNOON WEDNESDAY. HOWEVER...THE MAIN CONVERGENCE AXIS WITH THE
LEAD FRONT TRAILING THE SURFACE WAVE TRACKING FROM THE MID-SOUTH TO
NC COAST WILL HAVE DRIFTED INTO SOUTHERN OR SOUTHEASTERN NC BY WED
MORNING. AS SUCH...HAVE TRENDED POPS DOWNWARD INTO THE CHANCE
RANGE...RANGING FROM AROUND 30 PERCENT NW...TO 50 PERCENT IN CLOSEST
PROXIMITY TO THE LEAD FRONT/CONVERGENCE AXIS AND WHERE BOUNDARY
LAYER MOISTURE IN THE UPPER 60S IS LIKELY TO LINGER...OVER THE SE.
HIGHS...WITH A MIX OF SUN AND CLOUDS...AGAIN IN THE LOWER TO MIDDLE
80S. CLEARING AND COOLER WITH LOWS IN THE LOWER TO MIDDLE 60S
OVERNIGHT...THOUGH A FEW PATCHES OF STRATUS IN NE LOW LEVEL FLOW
WILL BE POSSIBLE LATE.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 315 AM TUESDAY...

THURSDAY THROUGH FRIDAY NIGHT...HIGH PRESSURE BUILDS ACROSS SOUTHERN
NEW ENGLAND SHORE...EXTENDING DOWN THE MID ATLANTIC COAST WITH DRY
NORTHEAST TO EAST FLOW. THE PLEASANT ENSUING COOL DAMMING SCENARIO
WILL LINGER INTO THE WEEKEND...WITH THICKNESSES INDICATIVE OF TEMPS
A GOOD CATEGORY BELOW NORMAL...LOW-MID 80S. WILL MAKE SOME GRID
ADJUSTMENTS ON THURSDAY AND FRIDAY TO FAVOR COOLER TEMPS IN THE
NORTHEAST WHERE MARITIME FLOW WILL BE STRONGEST/COOLEST. MINS WILL
BE GENERALLY LOW AND MID 60S.

SATURDAY THROUGH MONDAY...THE COOL SURFACE HIGH WILL WEAKEN AND
DRIFT EAST WITH A GRADUAL RETURN OF MORE SOUTHERLY FLOW BY LATE
WEEKEND. MEANWHILE...UPPER RIDGING WILL BUILD EAST OUT OF THE
MIDWEST INTO THE EASTERN CONUS SATURDAY THROUGH MONDAY. SOUTHERLY
FLOW WILL RESULT IN INCREASING HUMIDITY SUNDAY INTO MONDAY. WITH THE
CAPPING MID LEVEL RIDGE OVERHEAD...CONVECTION WILL BE ISOLATED
OUTSIDE OF PERHAPS SOME DIFFERENTIAL HEATING ON THE EASTERN SLOPES
AND POTENTIAL FOR SOME SEA BREEZE CONVECTION TO MIGRATE INLAND INTO
THE COASTAL PLAIN. AT THIS POINT...THE CHANCES ARE TOO SMALL TO
MENTION IN THE FORECAST. THE AIRMASS WILL GRADUALLY WARM UP WITH THE
SOUTHERLY FLOW AND PERSISTENCE OF THE UPPER RIDGE INTO MONDAY...
HIGHS WILL WARM FROM THE MID 80S SATURDAY TO THE UPPER 80S...PERHAPS
LOWER 90S ON MONDAY. MINS WILL BE IN THE 60S.

&&

.AVIATION /17Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 1210 PM TUESDAY...

A SURFACE COLD FRONT SLOWLY ADVANCING SOUTHEASTWARD WILL INTERACT
WITH THE MOIST AND SLIGHTLY UNSTABLE AIR MASS TO TRIGGER NUMEROUS
SHOWERS AND SCATTERED THUNDERSTORMS ACROSS CENTRAL NC LATER THIS
AFTERNOON THROUGH TONIGHT. THE SHOWER AND THUNDERSTORM COVERAGE IS
EXPECTED TO BE GREATEST BETWEEN 4 PM AND 10 PM. THE CONVECTIVE
ACTIVITY WILL CREATE WIDESPREAD MVFR CEILINGS/VISIBILITY WITH
POCKETS OF IFR CEILING/VISIBILITY IN THE HEAVIER SHOWERS.

THE COLD FRONT SHOULD CROSS THE TRIAD TERMINALS AROUND 10 PM...THE
KRDU/KRWI TERMINALS BETWEEN 1 AM AND 3 AM...AND THE KFAY VICINITY
BETWEEN 3-5 AM. AHEAD THE BOUNDARY EXPECT IFR CEILINGS ALONG WITH A
FEW SHOWERS. THE PASSAGE OF THE FRONT WILL BE NOTED BY SURFACE WINDS
VEERING FROM THE SW TO THE NORTH-NORTHWEST.

AVIATION CONDITIONS WILL BEGIN TO IMPROVE WEDNESDAY MORNING AS DRIER
MORE STABLE AIR FLOWS INTO THE REGION BEHIND THE EXITING FRONT.
EXPECT A RETURN TO VFR CONDITIONS THOUGH A STRATOCU DECK WILL LIKELY
DEVELOP WEDNESDAY AFTERNOON WITH BASES 3000-4000FT.

HIGH PRESSURE WILL BUILD INTO AND LINGER OVER CENTRAL NC WEDNESDAY
NIGHT THROUGH THE WEEKEND. THIS WEATHER SYSTEM WILL BRING DRY AND
STABLE CONDITIONS LEADING TO VFR PARAMETERS. THE EXCEPTION WILL BE A
BRIEF PERIOD OF MVFR VISIBILITY DUE TO FOG...MAINLY IN THE COASTAL
PLAIN.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...WSS
NEAR TERM...WSS/MWS
SHORT TERM...MWS
LONG TERM...MLM
AVIATION...WSS