Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 260522 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 121 AM EDT TUE MAY 26 2015 .SYNOPSIS...AN UPPER LEVEL RIDGE OVER THE REGION WILL SLOWLY SHIFT OFFSHORE THROUGH MID-WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 925 PM MONDAY... AN AREA OF HIGH PRESSURE AT THE SURFACE AND ALOFT WILL DRIFT SLOWLY EAST OVERNIGHT THROUGH TUESDAY. THE RETURN FLOW ON THE BACK SIDE OF THIS WEATHER SYSTEM WILL ADVECT A WETTER LOW LEVEL AIR MASS INTO CENTRAL NC. THIS WILL BECOME EVIDENT LATER TONIGHT IN THE FORMATION/ADVECTION OF A STRATUS LAYER OVERNIGHT THROUGH TUESDAY MORNING. THIS LAYER EXPECTED TO BE THICKER OVER THE WESTERN PIEDMONT VERSUS THE REST OF THE FORECAST AREA. AT THIS TIME...APPEARS THAT THE TRIANGLE AREA WILL BE ON THE EDGE OF THE BROKEN/OVERCAST LAYER. THUS LOCATIONS AROUND JORDAN LAKE AND DURHAM WILL LIKELY HAVE MOSTLY CLOUDY SKIES EARLY TUESDAY WHILE LOCATIONS CLOSER TO CLAYTON...WENDELL AND ZEBULON WILL LIKELY START OUT PARTLY CLOUDY/MOSTLY SUNNY. MAY ALSO POCKETS OF FOG DEVELOP OVER SECTIONS OF THE SANDHILLS AND SOUTHERN PIEDMONT. WHILE NOT EXPECTING DENSE FOG AT THIS TIME...VISIBILITIES MAY LOWER TO BETWEEN 1-3 MILES BETWEEN 6 AND 8 AM. THE INCREASE IN LOW LEVEL MOISTURE WILL RESULT IN A WARMER NIGHT COMPARED TO LAST NIGHT. MIN TEMPS IN THE LOW-MID 60S APPEAR ON TARGET WITH THE NORMALLY COLDER SITES IN THE NE CLOSE TO 60. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 200 PM MONDAY... ALTHOUGH THE PRONOUNCED UPPER LEVEL RIDGE WILL REMAIN ANCHORED JUST OFFSHORE THE SOUTHEAST COAST TUE/TUE NIGHT...THE RIDGE AXIS WILL SHIFT EASTWARD TO THE CAROLINA COAST...ESTABLISHING SW FLOW ALOFT/ SOUTHERLY RETURN FLOW OVER WESTERN NC/SC. INCREASING LOW-LEVEL MOISTURE WILL AID IN MARGINAL DIURNAL DESTABILIZATION AS FAR EAST AS THE HWY 1 CORRIDOR (ROUGHLY) TUE AFTERNOON...WITH MLCAPE VALUES RANGING FROM 500-1000 J/KG...HIGHEST IN THE WESTERN PIEDMONT. LITTLE OR NO LOW-LEVEL FORCING WILL BE PRESENT TUE AFTERNOON GIVEN THE PRONOUNCED SFC RIDGE AXIS EXTENDING INTO THE REGION FROM THE EAST. ALTHOUGH A SEABREEZE WILL LIKELY MARCH INLAND INTO EAST/SE PORTIONS OF CENTRAL NC...THERMODYNAMIC PROFILES IN THE SANDHILLS/COASTAL PLAIN WILL REMAIN SUBSIDENT AND UNSUPPORTIVE OF CONVECTION. ASIDE FROM THE POTENTIAL FOR WEAK/GLANCING DPVA ATTENDANT SMALL AMPLITUDE DISTURBANCES EMBEDDED WITHIN SW FLOW ALOFT ACROSS FAR WESTERN PORTIONS OF THE STATE...FORCING APPEARS NEGLIGIBLE IN CENTRAL NC. WILL INDICATE A SLIGHT CHANCE OF SHOWERS IN THE FAR WESTERN PIEDMONT LATE TUE AFTERNOON TO ACCOUNT FOR ISOLD MOUNTAIN CONVECTION PROPAGATING INTO THE WEST/SW PIEDMONT...THOUGH SOUTHWESTERLY FLOW ALOFT IS NOT PARTICULARLY CONDUCIVE THEREOF...NOT TO MENTION THE INCREASINGLY UNFAVORABLE THERMODYNAMIC ENVIRONMENT WITH EASTWARD EXTENT. WILL CONTINUE TO INDICATE A SLIGHT CHANCE OF SHOWERS IN THE FAR WESTERN PIEDMONT TUE NIGHT GIVEN CONTINUED MOISTENING AND A POTENTIAL FOR SMALL AMPLITUDE WAVES IN SW FLOW ALOFT...OR PERHAPS IN ASSOC/W UPSTREAM CONVECTION PROGRESSING INTO THE MOUNTAINS...THOUGH ANY SUCH ACTIVITY WOULD LIKELY DISSIPATE EAST OF THE BLUE RIDGE. EXPECT HIGHS TUE SIMILAR TO TODAY...WITH LOWS TUE NIGHT A FEW DEGREES WARMER IN THE MID TO UPPER 60S. -VINCENT && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 245 PM MONDAY... WEDNESDAY THROUGH FRIDAY...ONGOING MID RANGE FORECAST STILL LOOKS ON TRACK WITH THE AMPLIFIED UPPER LEVEL RIDGE HOLDING TIGHT ALONG THE EAST COAST. ECMWF AND GFS LOOK SIMILAR FOR MID-LATE WEEK...WITH THE RIDGING HAMPERING THE EASTWARD PROGRESSION OF AN APPROACHING SHORT WAVE AND ITS ASSOCIATED FRONTAL SYSTEM AND PRECIPITATION. THE DEEP RETURN FLOW AROUND THE STACKED RIDGING WILL RESULT IN INCREASED MOISTURE (PW`S >1.5 INCHES = CAPE >1K JOULES)...ESPECIALLY IN THE WEST...WHERE POPS WILL BE HIGHER DUE TO PROXIMITY OF THE STALLED FRONT AND ALSO AN INCREASED CHANCE FOR NON-DIURNAL ACTIVITY DUE TO THE POTENTIAL FOR PERTURBATIONS FROM UPSTREAM CONVECTION TO RIDE THE PREVAILING FLOW NORTHWARD ALONG THE FRONT. WILL MAINTAIN CHANCE POPS AT THIS POINT...FALLING OFF A BIT OVERNIGHT MAINLY IN THE EAST WITH LOSS OF INSOLATION. NO CHANGES ARE NEEDED IN THE TEMPERATURE FORECAST AS GUIDANCE CONTINUES TO TARGET HIGHS IN THE MID 80S WITH LOWS IN THE MID 60S. FRIDAY NIGHT THROUGH MONDAY...THE UPPER RIDGE REASSERTS ITSELF BY THE WEEKEND AS THE SHORT WAVE WHICH WAS INITIALLY BLOCKED BY THE RIDGING LIFTS NORTH OF THE AREA. THIS WILL ALLOW THE UPPER RIDGE TO RETROGRADE BACK ACROSS THE AREA AND SUPPRESS THE DEEPER MOISTURE PLUME WEST OF THE AREA. THE SUBSIDENCE=STRONGER CAPPING ALOFT WHICH WILL INHIBIT CONVECTION...AND ALSO NUDGE HIGH TEMPERATURES INTO THE UPPER 80S TO LOWER 90S SUNDAY AND MONDAY. WILL KEEP POPS IN THE LOW CHANCE RANGE AND SKEWED TOWARDS MAX HEATING DUE TO THE ABSENCE OF OTHER READILY IDENTIFIABLE LIFTING MECHANISMS TO ENHANCE ORGANIZATION OR NON-DIURNAL DISTRIBUTION. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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AS OF 120 AM TUESDAY... LOW-LEVEL MOISTURE RETURN ON THE WESTERN PERIPHERY OF THE DEEP LAYER RIDGE CENTERED JUST OFF THE EASTERN SEABOARD WILL SUPPORT AREAS OF STRATUS...ESPECIALLY ACROSS WESTERN PORTIONS OF THE STATE. CEILINGS IN THE IFR OR LOW END MVFR IS EXPECTED AT KINT AND KGSO WITH POCKETS OF LIFR CEILINGS POSSIBLE. THE LOW CEILINGS WILL PERSIST THROUGH THE MID MORNING HOURS...LIFTING INTO THE LOW END OF THE VFR CATEGORY AROUND EARLY AFTERNOON. PROBABILITIES OF SUB-VFR CEILINGS DEVELOPING THROUGH THIS MORNING SHOULD DECREASE WEST TO EAST...WITH A PERIOD OF SCATTERED TO BROKEN STRATUS BETWEEN 700-1200FT POSSIBLE AT KRDU. AT KRWI AND KFAY...THE STRATUS IS EXPECTED TO REMAIN FEW TO SCATTERED. A SHOWER OR THUNDERSTORM MAY THREATEN THE TRIAD TERMINALS LATE TUESDAY AFTERNOON THROUGH TUESDAY EVENING BUT THIS PROBABILITY APPEARS TOO LOW TO MENTION IN THE TERMINAL FORECAST AT THIS TIME. WIDESPREAD MVFR/IFR CEILINGS EXPECTED EACH MORNING THROUGH THE REMAINDER OF THE WORK WEEK AS SLY FLOW CONTINUES TO INCREASE OR MAINTAIN LOW LEVEL MOISTURE OVER CENTRAL NC. THERE WILL BE A BETTER CHANCE FOR AFTERNOON CONVECTION BOTH WEDNESDAY AND THURSDAY WITH THE GREATEST CHANCES ON WEDNESDAY OVER THE PIEDMONT...AND AREAWIDE THURSDAY. THE HIGH PRESSURE SYSTEM WILL BEGIN TO BUILD BACK INTO THE CAROLINAS FRIDAY INTO SATURDAY. THIS WILL BEGIN TO LIMIT THE CHANCES FOR AFTERNOON CONVECTION ON FRIDAY AND MORE SO SATURDAY. THERE WILL CONTINUE TO BE DECENT THREAT FOR EARLY MORNING MVFR/IFR CEILING AND FOG FRIDAY AND SATURDAY MORNINGS.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...WSS SHORT TERM...VINCENT LONG TERM...MLM AVIATION...CBL/WSS

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