Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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354
FXUS62 KRAH 060736
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
325 AM EDT FRI MAY 6 2016

.SYNOPSIS...
DEEP LOW PRESSURE WILL LINGER OVER THE MIDATLANTIC REGION TODAY
BEFORE MOVING NORTHEAST AWAY FROM THE AREA TONIGHT. HIGH PRESSURE
WILL BUILD OVER THE SOUTHEAST STATES SATURDAY BRINGING A WARM
SOUTHWEST FLOW INTO THE AREA. A COLD FRONT APPROACHING FROM THE
NORTHWEST SATURDAY NIGHT WILL STALL OUT NEAR THE VIRGINIA NORTH
CAROLINA BORDER SUNDAY INTO MONDAY.

&&


.NEAR TERM /TODAY AND TONIGHT/...
AS OF 315 AM FRIDAY...

UNSETTLED WEATHER PERSISTS TODAY BUT WITH SOME IMPROVEMENT FROM
YESTERDAY. LATEST SURFACE MAP SHOWS LOW PRESSURE OFFSHORE WITH WEAK
PINWHEELING TROUGHS ROTATING SOUTHWARD THROUGH OUR AREA... AND
WIDESPREAD RAIN CONTINUES OVER THE NRN AND WRN CWA ALONG THE
DEFORMATION ZONE. THE SLOW MOVING MID-UPPER LOW DRIVING THESE DREARY
CONDITIONS IS NOW CENTERED OVER ERN NC ACCORDING TO WATER VAPOR
IMAGERY... DRIFTING SLOWLY NORTHWARD AND ON PACE TO HAVE A GRADUALLY
DECREASING IMPACT ON OUR WEATHER... SHIFTING UP TO AROUND
PHILADELPHIA BY THIS EVENING... ACCOMPANIED BY THE SURFACE LOW. WILL
MAINTAIN HIGH POPS -- LIKELY TO CATEGORICAL -- THROUGH THIS MORNING
BEFORE THE DECREASING DYNAMIC FORCING AND INCREASING DOWNSLOPE-
ORIENTED LOW LEVEL WIND COMPONENT FOSTERS A WEST-TO-EAST DECREASING
TREND IN WIDESPREAD PRECIP. SUCCESSIVE WEAK LOBES OF VORTICITY WILL
CONTINUE TO PIVOT AROUND THE LOW THROUGH TODAY... SWEEPING ACROSS
NRN AND ERN NC WHERE PW VALUES REMAIN ABOVE NORMAL. MID LEVEL LAPSE
RATES WILL NOT BE QUITE AS HIGH AS THEY WERE YESTERDAY BUT STILL
ELEVATED... 6.5-7.0 C/KM... FOCUSED ON OUR WESTERN SECTIONS THIS
AFTERNOON BEFORE SHIFTING OVER THE SOUTHEAST FORECAST AREA AND ERN
NC INTO THE EVENING. THE RESULTING WEAK AFTERNOON INSTABILITY
COMBINED WITH THE MID LEVEL SHEAR AXIS OVER THE AREA WILL PROMPT
ADDITIONAL SHOWER DEVELOPMENT MAINLY ACROSS THE NRN AND ERN CWA THIS
AFTERNOON... DWINDLING SLOWLY THIS EVENING. THE RISK OF THUNDER
REMAINS BUT SHOULD BE LOWER THAN YESTERDAY WITH MINIMAL INSTABILITY
PROJECTED BY MODELS... JUST A COUPLE HUNDRED J/KG AT MOST... SO WILL
MAINTAIN JUST AN ISOLATED MENTION THIS AFTERNOON. THICKNESSES
RECOVER A BIT BUT REMAIN COOL... SUPPORTING HIGHS FROM THE LOWER 60S
NE (WHERE ANY RAIN-FREE PERIOD WILL BE RELATIVELY BRIEF) TO LOWER
70S SW (WHERE SOME PARTIAL MID TO LATE AFTERNOON SUNSHINE IS
POSSIBLE). SKIES SHOULD SLOWLY TREND TOWARD PARTIAL CLEARING SW TO
NE TONIGHT AS THE MID LEVEL TROUGH AXIS SHIFTS TO COASTAL AND
OFFSHORE NC/SC DESPITE THE NEARLY STATIONARY BUT FILLING LOW TO OUR
NORTH. LOWS IN THE UPPER 40S TO LOWER 50S. -GIH

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 330 AM FRIDAY...

WE FINALLY BREAK OUT OF THE DISMAL PATTERN AS THE MID LEVEL LOW AND
TROUGH PUSH EASTWARD WELL OFF THE COAST... FOLLOWED BY WEAKER AND
GENTLY ANTICYCLONIC NW MID LEVEL FLOW... AND WSW LOW LEVEL FLOW...
LEADING TO A DRYING/SUBSIDING COLUMN AND WARMING/WELL-MIXED LOW
LEVELS... WITH PARTLY TO MOSTLY SUNNY SKIES ON SATURDAY. HIGHS 72-
79. SOME CLOUDS WILL RETURN SAT NIGHT MAINLY ACROSS THE NORTH HALF
AS A STRONG POLAR LOW OVER THE ONT/QUE BORDER DIGS NEGATIVELY
THROUGH THE ST LAWRENCE VALLEY/NORTHEAST AND DRIVES A BACKDOOR FRONT
SOUTHWARD TOWARD THE VA/NC STATE LINE. THE DYNAMICS AND INCREASING
MID LEVEL FLOW ALONG THIS FRONT SUGGEST THAT SOME CONVECTION IS
POSSIBLE LATE SAT OVER THE OH VALLEY... AND THIS ACTIVITY COULD DROP
SSE INTO OUR FAR NORTH... SO WILL HAVE A SLIGHT CHANCE POP HERE SAT
EVENING/NIGHT. SEASONABLE LOWS IN THE MID 50S TO AROUND 60. -GIH

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...

A COLD FRONT WILL CROSS THE AREA EARLY SUNDAY...BUT HOW FAR SOUTH
INTO NC THE FRONT MAKES IT REMAINS TO BE SEEN WITH THE GFS PUSHING
THE COOL AIR A LITTLE FURTHER SOUTH. IN THE WAKE OF THE FRONT...HIGH
PRESSURE BUILDING IN OVER FLORIDA SHOULD HELP TO BUMP UP
TEMPERATURES...ESPECIALLY IN THE SOUTHERN COUNTIES WHERE MID 80S
WILL BE PROBABLE HIGHS WITH CLOSER TO 80 ACROSS THE NORTH.
ALOFT...NORTHWESTERLY FLOW WILL GUIDE A FEW SMALL DISTURBANCES
ACROSS THE AREA DURING THE DAY BUT ANY PRECIPITATION SHOULD BE LIGHT
AND FLEETING. STILL WILL CARRY SLIGHT CHANCES ACROSS MUCH OF THE CWA
SUNDAY AFTERNOON. LOWS SUNDAY NIGHT IN THE MID 50S TO NEAR 60
DEGREES. MONDAY AND MONDAY NIGHT...DETERMINISTIC MODELS ARE STILL IN
FAIRLY GOOD AGREEMENT ABOUT THE DEVELOPMENT OF A LOW PRESSURE SYSTEM
OVER THE CENTRAL PLAINS WITH A WARM FRONT HOVERING NORTH OF NC ON
MONDAY AS SURFACE HIGH PRESSURE CAMPS OUT OVER THE WESTERN ATLANTIC.
THIS SHOULD KEEP CONDITIONS DRY AND WARM WITH HIGHS IN THE LOW TO
MID 80S AND LOWS MONDAY NIGHT IN THE LOW TO MIDDLE 60S.

CONFIDENCE IN THE FORECAST BEGINS TO BREAK DOWN ON TUESDAY AS MODELS
ARE IN DISARRAY OVER THE HANDLING OF THE NORTHERN STREAM SYSTEM AS
THE GFS DEVELOPS AN UPPER LEVEL LOW THAT MAINTAINS THE CENTRAL
PLAINS SURFACE LOW. THIS FEATURE DOES NOT EXIST IN THE ECMWF AND THE
SURFACE LOW DEGRADES AND IS CARRIED OFF TO THE EAST. A BLEND OF THE
MODELS WOULD SUGGEST NOT TOO MUCH PRECIPITATION ACROSS CENTRAL NC IF
ANY AND CONTINUED WARM TEMPERATURES. BEST CHANCES WOULD BE ACROSS
THE NORTH WITH THE POTENTIAL FOR A THUNDERSTORM IF CONVECTION DOES
OCCUR. WEDNESDAY ONWARD...A BLEND OF THE ENSEMBLES IS THE MORE
FAVORED SOLUTION  WHICH WILL GENERALLY INCREASE POPS ON WEDNESDAY
WITH CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE AFTERNOON. EXTREME
DIFFERENCES IN THE MODELS ON THURSDAY CAUSE EVEN A BLEND OF THE
MODELS TO BE MEANINGLESS AT THIS POINT. THEREFORE WILL CONTINUE
SLIGHT CHANCE/CHANCE POPS THROUGH THURSDAY BUT WITH NO REAL
CONFIDENCE. LOW TO MID 80S THROUGH THE REST OF THE PERIOD WITH LOWS
IN THE MID 60S.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 105 AM FRIDAY...

ADVERSE AVIATION CONDITIONS WILL PERSIST AT RDU/RWI/FAY THROUGH MUCH
OF THE MORNING... MOSTLY MVFR WITH OCCASIONAL IFR CIGS... WHILE VFR
CIGS AND MVFR/VFR VSBYS HOLD AT INT/GSO. DEEP LOW PRESSURE HOLDING
OVER THE MIDATLANTIC COASTAL AREAS WILL CONTINUE TO BRING UNSETTLED
WEATHER WITH PERIODS OF RAIN ESPECIALLY AT INT/GSO/RDU/RWI THROUGH
MID MORNING. THE AXIS OF STEADY RAIN WILL THEN SHIFT INTO THE
NORTHEAST SECTIONS... WITH RAIN CHANCES DWINDLING AT INT/GSO BUT
PERSISTING AT RDU/RWI/FAY THROUGH THE AFTERNOON HOURS... BRINGING
PERIODS OF MVFR VSBYS/CIGS. BUT OTHERWISE CIGS SHOULD TREND UP TO
VFR BY 16-17Z TODAY AT RDU/FAY AND BY 18-19Z AT RWI... AS THE LOW
PRESSURE STARTS TO MOVE NE AWAY FROM THE AREA. ANY REMAINING RAIN
CHANCES NEAR RDU/RWI/FAY WILL DIMINISH SOON AFTER SUNSET... WITH DRY
WEATHER AND VFR CIGS EXPECTED AFTER 03Z TONIGHT. SURFACE WINDS WILL
BE MAINLY FROM THE NW THIS AFTERNOON AT 8-14 KTS.

LOOKING BEYOND 06Z EARLY SAT MORNING... VFR CONDITIONS ARE LIKELY TO
DOMINATE AT ALL SITES THROUGH TUESDAY... WITH HIGH PRESSURE BUILDING
OVER THE GULF AND SOUTHEAST STATES... A SW LOW INTO NC... AND A
FRONTAL ZONE WHICH STALLS OUT NEAR THE NC/VA LINE LATE IN THE
WEEKEND. THIS FRONT WILL SHIFT NORTH AS A WARM FRONT MON/TUE... WITH
SOUTHWEST FLOW PERSISTING... AND ISOLATED STORM CHANCES EACH
AFTERNOON. -GIH

&&

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

&&

$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...ELLIS
AVIATION...HARTFIELD



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