Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 301757 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 157 PM 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 1030 AM SATURDAY... VISIBLE SATELLITE IMAGERY SHOWS EXTENSIVE SHIELD OF STRATOCUMULUS EAST OF US 1 THAT WILL BUILD NORTHWESTWARD WITH TIME. A LITTLE BIT OF DRIER AIR IN THE TRIAD KEEPING IT MOSTLY CLEAR AT THIS TIME THERE. AS FAR AS CEILING RESTRICTIONS ARE CONCERNED THERE ARE STILL SOME MVFR CEILINGS OUT THERE THAT SHOULD BE BURNING OFF WITHIN THE NEXT HOUR OR TWO BUT OTHERWISE MOST SITES RETURNING TO VFR. MOSTLY SEA BREEZE SHOWERS THIS AFTERNOON BUT REALLY NOT MUCH TO SPEAK OF AS FAR AS PRECIPITATION IS CONCERNED AS INSTABILITY WILL BE SUPPRESSED BY THE SURFACE HIGH AND THE UPPER LEVEL RIDGE RIGHT OVERHEAD. SHEAR CONTINUES TO BE MINIMAL. HIGHS IN THE UPPER 80S TO LOW 90S IN MOST LOCATIONS. OVERNIGHT EXPECT LOWS IN THE MID TO UPPER 60S WITH ANOTHER CHANCE FOR SOME FOG/LOW STRATUS NEAR DAYBREAK. && .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 /18Z SATURDAY THROUGH THURSDAY/...
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AS OF 200 PM SATURDAY... 24 HOUR TAF PERIOD: STUBBORN MVFR STRATUS FINALLY HAS LIFTED TO VFR LEVELS THIS AFTERNOON AT ALL SITES AND VFR CONDITIONS ARE PREVAILING. VERY MINIMAL SHOWER ACTIVITY AT THIS TIME IN THE EXTREME SOUTHWEST WITH THE SEA BREEZE STARTING TO KICK OFF A FEW WEAK SHOWERS NEAR THE COAST. WITH THIS IN MIND KFAY OR KINT OR KGSO WOULD BE THE MOST LIKELY SPOTS TO SEE ANY CONVECTION THIS AFTERNOON BUT PARAMETERS ARE WEAKER THAN YESTERDAY AT THIS TIME AND THE RADAR TELLS THAT STORY. OVERNIGHT TONIGHT THERE IS ANOTHER CHANCE FOR SOME FOG/LOW STRATUS NEAR DAY BREAK. CONFIDENCE IN LOCATION OR LENGTH IS UNCERTAIN AT THIS TIME AS MODEL SOLUTIONS DISAGREE. LOW STRATUS IS MORE LIKELY THAN FOG BUT WE DID SEE POCKETS OF BOTH THIS MORNING ACROSS THE AREA. THE LATEST NAM RH CROSS SECTIONS PICK THE TRIAD AS THE MOST LIKELY SPOT BUT FORECAST SOUNDINGS ARE ALSO HINTING AT KFAY AND KRWI AS CANDIDATES FOR SOME ADVERSE CONDITIONS. LONG TERM: THE MAIN FRONTAL SYSTEM SHOULD BEGIN TO FINALLY MOVE EAST EARLY NEXT WEEK SO MOST OF NEXT WEEK WILL CONTAIN A PATTERN FAVORABLE FOR ADVERSE AVIATION CONDITIONS WITH DIURNAL SHOWERS AND THUNDERSTORMS AND CHANCES FOR FOG/STRATUS DURING THE EARLY MORNING HOURS MOST DAYS.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD/BLAES NEAR TERM...ELLIS SHORT TERM...BSD LONG TERM...WSS AVIATION...ELLIS

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