Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 300703
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
305 AM EDT SAT MAY 30 2015

.SYNOPSIS...HIGH PRESSURE CENTERED OVER THE WESTERN ATLANTIC WILL
EXTEND INTO THE REGION THROUGH SUNDAY MORNING. A COLD FRONT WILL
DROP INTO THE MID ATLANTIC AND SOUTHERN APPALACHIANS ON SUNDAY AND
MOVE INTO THE CAROLINAS ON MONDAY AND TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM SATURDAY...

SURFACE HIGH PRESSURE WILL CONTINUE TO EXTEND INTO THE AREA FROM THE
WESTERN ATLANTIC TODAY... WHILE A MID/UPPER LEVEL RIDGE REMAINS OVER
THE AREA. THIS WILL AGAIN LARGELY SUPPRESS CONVECTION TODAY... WITH
NEAR TERM GUIDANCES SHOWING EVEN LESS INSTABILITY THAN YESTERDAY.
THIS SHOULD GENERALLY YIELD A DRY DAY ACROSS THE AREA... WITH THE
BEST CHANCES OF SEEING ANY ISOLATED SHOWERS/STORMS IN THE FAR
NORTHWEST PIEDMONT. OTHERWISE... EXPECT WE COULD SEE SOME PATCHY FOG
AND LOW STRATUS ACROSS THE AREA... LIFTING BY MID MORNING... WITH
PARTLY TO EVEN MOSTLY SUNNY SKIES EXPECTED TODAY. LOW LEVEL
THICKNESS VALUES WILL AGAIN BE SIMILAR TO YESTERDAY. THUS... WOULD
EXPECT TEMPS TO RANGE FROM THE MID 80S NW TO THE UPPER 80S/NEAR 90
ELSEWHERE... SIMILAR TO FRIDAY`S HIGHS.

MORE OF THE SAME IS EXPECTED TONIGHT... WITH AGAIN THE POTENTIAL FOR
SOME PATCHY PRE-DAWN/EARLY MORNING FOG/STRATUS AND LOW TEMPS
GENERALLY IN THE MID TO UPPER 60S.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 250 AM SATURDAY...

A WEAK SLOW MOVING MID LEVEL TROUGH WILL SLOWLY SHIFT EASTWARD ON
SUNDAY ACROSS THE MIDWEST AND DEEP SOUTH. THIS WILL ALLOW/CAUSE THE
MID LEVEL RIDGE TO SHIFT EASTWARD... WITH INCREASING SOUTHWESTERLY
FLOW ALOFT OVER CENTRAL NC. THIS SHOULD LEAD TO A BETTER CHANCE OF
SEEING SOME CONVECTION ON SUNDAY... MAINLY IN THE LATE
AFTERNOON/EVENING TIME FRAME... WITH THE HIGHEST PROBABILITIES
ACROSS THE NORTHWEST PIEDMONT. IN FACT FURTHER EASTWARD ACROSS THE
CENTRAL AND SOUTHERN COASTAL PLAIN WE MAY SEE DRY CONDITIONS
CONTINUE TO PREVAIL. HIGHS TEMPS WILL AGAIN BE SIMILAR TO TODAY...
MAYBE A FEW DEGREES COOLER IN THE NORTHWEST PIEDMONT. STILL THINK WE
SHOULD SEE HIGHS RANGING FROM THE MID TO UPPER 80S THOUGH. GIVEN THE
SOUTHWESTERLY MID LEVEL FLOW AND POTENTIAL FOR WEAK PERTURBATIONS TO
MOVE ACROSS THE AREA AND ALONG WITH THE MOIST AIRMASS IN PLACE ON
SUNDAY NIGHT WE MAY SEE AFTERNOON CONVECTION LINGER A BIT LONGER...
ALONG WITH THE POTENTIAL FOR AT LEAST ISOLATED CONVECTION POSSIBLE
ACROSS THE WESTERN AND NORTHERN PIEDMONT ALL NIGHT LONG... DEPENDING
ON ANY WEAK DISTURBANCES ALOFT IN THE SOUTHWESTERLY FLOW. WRT TO ANY
SEVERE POTENTIAL... MIXED LAYER CAPE STILL APPEARS TO BE WEAK TO
MODEST AT BEST... WITH GENERALLY ONLY 500 TO 1300 J/KG OF MLCAPE.
GIVEN THIS AND STILL WEAK DEEP LAYER SHEAR... THINK SVR THREAT WILL
BE QUITE MINIMAL TO NIL FOR SUNDAY AFTERNOON INTO SUNDAY NIGHT. LOWS
BY MONDAY MORNING ARE EXPECTED TO BE IN THE MID TO UPPER 60S AGAIN.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 305 AM SATURDAY...

THE APPROACH OF A MINOR S/W AND ATTENDANT COLD FRONT WILL INCREASE
THE THREAT FOR SHOWERS AND THUNDERSTORMS MONDAY INTO TUESDAY AS IT
INTERACTS WITH THE MOIST AND SLIGHTLY UNSTABLE AIR MASS OVER CENTRAL
NC. BASED ON MODEL TIMING (AND DECENT CONSENSUS)...APPEARS BULK OF
LIFT TO INITIATE/SUSTAIN CONVECTION WILL OCCUR IN THE WESTERN
PIEDMONT LATE MONDAY...AND OVER THE REMAINDER OF CENTRAL NC MONDAY
NIGHT. FORCING PRETTY MUCH DEPENDENT ON UPPER DIVERGENCE ALOFT
ATTRIBUTED TO AN UPPER JET LIFTING NE ACROSS THE NORTHERN MID
ATLANTIC AND A WEAKENING SHEAR AXIS. FORCING ALONG THE 850MB AND
700MB FAIRLY ANEMIC. BASED ON THIS...WILL LIMIT POP CHANCE TO HIGH
END CHANCE/LOW END LIKELY.

LOOKING AT SEVERE PARAMETERS...WIND SHEAR WEAK WHILE AVAILABLE
INSTABILITY ADEQUATE FOR SOME DEEP CONVECTION. OVERALL SEVERE
WEATHER THREAT MARGINAL AT BEST AS STORM TYPE WILL BE MULTI-
CELLULAR/PULSE TYPE.

SFC COLD FRONT WILL GLIDE INTO THE NORTHERN-WESTERN PIEDMONT LATE
MONDAY NIGHT...THEN DRIFT SEWD TUESDAY. THIS FEATURE WILL AID TO
FOCUS MOST OF THE CONVECTIVE ACTIVITY OVER THE SANDHILLS AND COASTAL
PLAIN...ESPECIALLY TUESDAY AFTERNOON. MID LEVEL FLOW VEERS TO A MORE
WLY FLOW BY TUESDAY. THIS TYPE OF FLOW PATTERN USUALLY LIMITS
CONVECTIVE COVERAGE. WILL ALIGN POPS FROM CHANCE NW TO LOW END
LIKELY IN THE EAST AND FAR SOUTH...MAINLY IN THE AFTERNOON-EVENING
HOURS.

HIGH TEMPS MONDAY AND TUESDAY DEPENDENT UPON THE AMOUNT OF CLOUD
COVER AND INITIATION TIME OF CONVECTION. CURRENTLY HAVE MAX TEMPS
MONDAY MID-UPPER 80S...AND AROUND 80 NORTH TO THE MID 80S FAR SOUTH
TUESDAY. IF CONVECTION ON MONDAY DOES NOT INITIATE IN THE WEST UNTIL
LATE IN THE DAY...MAX TEMPS MAY END UP BEING 2-4 DEGREES WARMER.
SIMILARLY...IF OVERCAST SKIES PERSIST ACROSS THE NORTHERN PIEDMONT
MOST OF THE DAY...HIGH TEMPS MAY FAIL TO REACH 80.

WEDNESDAY THROUGH FRIDAY...S/W IN THE NORTHERN STREAM EXITS OFF THE
NEW ENGLAND COAST EARLY WEDNESDAY. THIS WILL ALLOW HIGH PRESSURE TO
BUILD INTO THE UPPER OH VALLEY AND NOSE SWD TOWARD CENTRAL NC. SOME
OF THE DRIER/MORE STABLE AIR WILL BLEED SWD INTO THE NORTHERN
PIEDMONT. FORMER FRONTAL BOUNDARY WILL LIE IN VICINITY OF THE NC/SC
BORDER AND GRADUALLY FIZZLE OUT. REMNANTS OF THIS BOUNDARY WILL
STILL SERVE AS A FOCUS FOR MOISTURE POOLING AND PROBABLY TRIGGER
ISOLATED TO SCATTERED CONVECTION OVER OUR FAR SOUTHERN-SE COUNTIES
WEDNESDAY INTO THURSDAY.

00Z GFS HAS INTENSIFIED AN AREA OF LOW PRESSURE IN THE NW CARIBBEAN
AND LIFTS IT NWD THROUGH THE FL PENINSULA THURSDAY. THIS IS A BIG
DEPARTURE FROM ITS PREVIOUS RUNS. 00Z ECMWF FAIRLY CONSISTENT WITH
ITSELF...DEPICTING AN INVERTED TROUGH IN THIS REGION. WILL LEAN
TOWARD THE ECMWF FOR NOW WHICH HAS A PIECE OF AN UPPER LEVEL RIDGE
LEANING EWD ACROSS OUR REGION. IF THIS VERIFIES...EXPECT POPS
CHANCES TO DWINDLE THURSDAY INTO FRIDAY WITH HIGH TEMPS CLOSE TO OR
SLIGHTLY ABOVE NORMAL.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1250 AM SATURDAY...

24-HR TAF PERIOD: VFR CONDITIONS ARE GENERALLY EXPECTED TO CONTINUE
THROUGH THE 24 HOUR TAF PERIOD... ASIDE FROM THE POTENTIAL FOR SOME
PATCHY SUB-VFR CIGS AND/OR FOG DURING THE PRE-DAWN/EARLY MORNING
HOURS THIS MORNING (08-14Z). GIVEN THE RATHER PATCHY NATURE OF THE
SUB-VFR CONDITIONS YESTERDAY MORNING... WILL KEEP MENTION OF MAINLY
SUB-VFR CIGS IN A TEMPO GROUP FOR NOW. OTHERWISE... VFR CONDITIONS
ARE EXPECTED TO PREVAIL THROUGH THE TAF PERIOD IN ASSOC/W A
PERSISTENT UPPER LEVEL RIDGE ALONG THE EASTERN SEABOARD... WHICH
SHOULD HELP TO LIMIT AFTERNOON/EVENING SHOWERS AND STORMS. THE BEST
CHANCES OF SEEING ANY AFTERNOON/EVENING SHOWERS AND/OR STORMS WILL
AGAIN BE IN THE TRIAD (KGSO/KINT)... THOUGH EVEN LOWER PROBABILITIES
THAN YESTERDAY. THUS... WILL NOT INCLUDE ANY MENTION OF CONVECTION
IN THE TAFS AT THIS TIME. -BSD

LOOKING AHEAD: ASIDE FROM A POTENTIAL FOR SUB-VFR CEILINGS/FOG
DURING THE EARLY MORNING (08-13Z) AND CONVECTION DURING THE LATE
AFT/EVE (20-01Z)...PRIMARILY AT THE INT/GSO TERMINALS...EXPECT VFR
CONDITIONS TO PREVAIL THROUGH THE WEEKEND. CHANCES FOR EARLY MORNING
STRATUS/FOG AND AFT/EVE CONVECTION WILL INCREASE AT ALL TERMINALS
(PARTICULARLY INT/GSO) MONDAY INTO TUESDAY AS THE UPPER LEVEL RIDGE
WEAKENS AND A SLOW-MOVING UPPER LEVEL TROUGH APPROACHES THE
CAROLINAS/MID-ATLANTIC FROM THE WEST. -VINCENT

&&

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

&&

$$

SYNOPSIS...BSD/BLAES
NEAR TERM...BSD
SHORT TERM...BSD
LONG TERM...WSS
AVIATION...BSD/VINCENT



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