Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 291746
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
145 PM EDT FRI APR 29 2016

.SYNOPSIS...THE STATIONARY FRONT LOCATED IN VICINITY OF THE
VIRGINIA BORDER THE PAST 48 HOURS WILL SAG SOUTH SOUTHWEST THROUGH
CENTRAL NORTH CAROLINA AS A BACK DOOR COLD FRONT TODAY...STALL NEAR
THE SOUTH CAROLINA BORDER TONIGHT...THEN GRADUALLY LIFT BACK TO THE
NORTH AS A WARM FRONT SATURDAY INTO SATURDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1050 AM FRIDAY...

LOW CLOUDS SLOWLY ERODING FROM THE SW THIS MORNING WITH THE CLEARING
LINE AT 1430 EXTENDING FROM ROXBORO-RALEIGH-FAYETTEVILLE.
CLOUDS WILL CONTINUE TO SLOWLY ERODE FROM THE WEST-SW....REACHING
THE RZZ VICINITY AROUND 17Z-18Z. EROSION PROCESS WILL RESULT IN A
WIDE VARIANCE IN MID AFTERNOON TEMPS ACROSS THE CWA. 19Z TEMPS
SHOULD VARY FROM THE LOW/MID 80S OVER THE SOUTHERN PIEDMONT TO
AROUND 70 OVER THE FAR NORTHERN COASTAL PLAIN.

TONIGHT...NARROW RIDGE OF HIGH PRESSURE WILL SCOOT EAST. THIS WILL
ALLOW A RETURN FLOW OF MOISTURE TO OCCUR OVER THE SOUTHERN AND
WESTERN PIEDMONT. THIS WILL BE IN CONTRAST TO THE NE
PIEDMONT/NORTHERN COASTAL PLAIN WHERE THE RETURN WILL NOT BECOME
ESTABLISHED UNTIL AFTER DAYBREAK. AREAS OF MID-HIGH LEVEL CLOUDS
WILL TRAVERSE EAST ACROSS THE REGION OVERNIGHT THOUGH NOT ENOUGH
LIFT NOTED TO GENERATE PRECIPITATION. MIN TEMPS SHOULD VARY FROM THE
MID 50S NE TO THE LOWER 60S SW.


&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 340 AM FRIDAY...

A HYBRID CAD EVENT IS LIKELY OVER THE PIEDMONT DAMMING REGION THIS
WEEKEND. MODELS CAN NOT BE TRUSTED WITH THE HYBRID CAD... NOR
PLACEMENT OF THE WARM FRONT.

A ~1023-1025 MB SURFACE HIGH PRESSURE IS FORECAST TO BUILD SOUTHWARD
INTO NORTH CAROLINA LATE FRIDAY NIGHT AND SATURDAY MORNING. THE
PARENT HIGH IS ACTUALLY IN A FAVORABLE POSITION AND OF FAVORABLE
STRENGTH TO ADEQUATELY DELIVER ENOUGH LOW LEVEL COOL STABLE AIR INTO
OUR REGION TO SET UP A HYBRID PIEDMONT COLD AIR DAMMING (WARM
SEASON) EVENT BEGINNING SATURDAY AND LASTING INTO SUNDAY. THE HIGH
PRESSURE WILL SLOWLY MOVE EAST AND OFFSHORE OF THE NORTHERN MID-
ATLANTIC COAST LATE SATURDAY... YET THE FOUNDATION OF CAD WILL BE IN
PLACE OVER THE NW PIEDMONT... AND LIKELY EVENTUALLY LOCKED IN PLACE
BY THE EXPECTED RAINFALL AND SUBSEQUENT DIABATIC PROCESSES. THE
RESIDUAL COOL STABLE LOW LEVEL AIR MASS WILL PLAY HAVOC ON SENSIBLE
WEATHER THIS WEEKEND. THIS DEVELOPS AS THE WARM AIR ADVECTION
PATTERN ALOFT RAPIDLY TRANSPIRES AS THE NEXT POTENT SYSTEM THAT WILL
BE APPROACHING FROM THE WEST THIS WEEKEND. THERE WILL BE PLENTY OF
AVAILABLE DEEP MOISTURE TO SURGE BACK NORTHWARD ALONG AND THEN ATOP
A NEARLY STATIONARY LOW LEVEL BOUNDARY... AS THE WESTERN ATLANTIC
AND GULF ARE TAPPED. RAIN IS EXPECTED TO DEVELOP MOST LIKELY LATE
SATURDAY MORNING INTO THE AFTERNOON FROM SOUTH TO NORTH. MODELS AND
ENSEMBLES SHOW CONSIDERABLE SPREAD WITH TIMING OF ONSET... BUT THE
EARLIER TIMING USUALLY WINS OUT IN THESE RESUMES. THE FAVORED HIGHER
QPF WILL BE IN THE WEST... WITH LOWER POP/QPF SE.

THE LATEST SEVERAL RUNS OF THE OPERATIONAL EC APPEAR TO BE FIT THE
OVERALL PATTERN AND OUR THINKING BETTER THAN THE NAM AND GFS WITH
THE TIMING OF ONSET OF RAIN AND THE EVENTUAL EVOLUTION OF THE CAD
EVENT OVER THE REGION SATURDAY NIGHT INTO SUNDAY. ONCE THE RAIN
DEVELOPS ON SATURDAY AFTERNOON... IT IS EXPECTED TO BECOME
WIDESPREAD OVER THE PIEDMONT DAMMING REGION... ESPECIALLY THE
WESTERN AND NORTHERN PIEDMONT... WITH THE RAIN BECOMING MORE AND
MORE SPOTTY WITH TIME IN THE SE ZONES. THIS WILL OCCUR AS THE WARM
FRONT TRIES TO COME NORTHWARD BUT WILL LIKELY A VERY DIFFICULT TIME
GETTING INTO THE CAD REGION OF THE PIEDMONT SATURDAY NIGHT AND
SUNDAY MORNING. AS THE STORM SYSTEM LIFTS WEST OF THE APPALACHIANS
SUNDAY AND SUNDAY NIGHT THERE SHOULD CONTINUE TO BE ENOUGH
ISENTROPIC LIFT TO KEEP THE RAIN/SHOWERS GOING ESPECIALLY OVER THE
WESTERN TWO THIRDS OF OUR REGION. THIS WILL MOST LIKELY KEEP THE LOW
LEVEL COOL POOL AND DAMMING IN PLACE INTO SUNDAY. FINALLY... AS THE
MAIN STORM MOVES FROM THE CENTRAL APPALACHIANS TO VA/MD... THE
TRAILING COLD FRONT WILL PUSH INTO THE REGION... THEN LIKELY STALL
SUNDAY NIGHT AND MONDAY.

SENSIBLE WEATHER SATURDAY INTO SUNDAY... COOL WITH PERIODS OF RAIN
WEST AND NORTH. AREAS OF FOG AND DRIZZLE. HIGHS GENERALLY 60S... OR
WELL BELOW CURRENT MOS STATISTICS. LOWS SATURDAY NIGHT HOLDING
STEADY IN THE 60S. HIGHS SUNDAY NEAR 70. QPF AROUND 0.50 TO 1 INCH.

LARGE TEMPERATURE SPREAD POTENTIAL FOR SUNDAY...

FOR AREAS FROM THE SANDHILLS INTO THE CENTRAL COASTAL PLAIN... A
CHANCE OF SHOWERS SATURDAY... SHOWERS LIKELY SATURDAY NIGHT AND
SUNDAY. HIGHS IN THE LOWER TO MID 70S. LOWS IN THE 60S. HIGHS SUNDAY
IN THE 70S TO LOWER 80S SC/NC BORDER AREA.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...

ANOTHER WAVE OR SEVERAL WAVES ARE FAVORED TO DEVELOP OVER THE SE
STATES EARLY TO MID WEEK AS THE UPPER LEVEL TROUGH BECOMES
ESTABLISHED OVER THE REGION. THE FRONT MENTIONED ABOVE WILL SETTLE
JUST TO OUR SOUTH AND EAST AND BECOME QUASI-STATIONARY MONDAY-
WEDNESDAY. THERE IS PLENTY OF SPREAD WITH THE ENSEMBLES AS TO TIMING
OF KEY RAIN PRODUCERS... SO WE WILL SIMPLY BROADBRUSH GOOD CHANCES
OF RAIN. WE WILL ALSO ADVERTISE COOLER THAN NORMAL READINGS DUE TO
THE TROUGH ALOFT... PREVALENT NE LOW LEVEL FLOW... CONSIDERABLE
CLOUDINESS... AND SEVERAL SIGNIFICANT RAIN CHANCES. LOWS GENERALLY
IN THE 50S TO LOWER 60S SE. HIGHS IN THE MID 60S TO MID 70S...
EXCEPT 75-80 SE MONDAY.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 145 PM FRIDAY...

THE LAST VESTIGES OF LOW STRATUS OVER THE NORTHERN COASTAL PLAIN IN
VICINITY OF KRWI AND KRZZ WILL LIFT/DISSIPATE PRIOR TO 20Z.
OTHERWISE WEAK HIGH PRESSURE AT THE SURFACE WILL MAINTAIN VFR
PARAMETERS THROUGH 04Z SATURDAY.

OVERNIGHT/AFTER 05Z...WIDESPREAD IFR/LIFR CONDITIONS DUE TO LOW
CEILINGS WILL DEVELOP. THE ADVERSE AVIATION CONDITIONS WILL PERSIST
THROUGH SATURDAY NIGHT. AREAS OF LIGHT RAIN WILL DEVELOP OVER THE
SOUTHERN PIEDMONT SATURDAY AFTERNOON...AND OVERSPREAD THE REMAINDER
OF CENTRAL NC THROUGH SATURDAY NIGHT.

SUB VFR CONDITIONS EXPECTED SUNDAY MORNING WITH SLOW IMPROVEMENT IN
AVIATION CONDITIONS SUNDAY AFTERNOON THROUGH MONDAY. AN UNSETTLED
WEATHER PATTERN IS EXPECTED TO RESULT IN VARIABLE AVIATION
CONDITIONS THROUGH WEDNESDAY. IT IS HIGHLY PROBABLE THAT MVFR/IFR
PARAMETERS WILL OCCUR DUE TO CEILINGS.

&&

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

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...WSS
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...WSS



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