Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 310101 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 900 PM EDT SAT MAY 30 2015 .SYNOPSIS...BERMUDA HIGH PRESSURE WILL EXTEND OVER THE REGION TONIGHT AND SUNDAY BEFORE GIVING WAY TO AN APPROACHING COLD FRONT FROM THE NORTHWEST MONDAY. THE FRONT IS EXPECTED TO STALL OVER THE REGION BY MID WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 900 PM SATURDAY... SURFACE HIGH PRESSURE WAS LOCATED OFF IN THE WESTERN ATLANTIC THIS EVENING. THIS WAS SUPPLYING A BROAD SOUTHEASTERLY FLOW ACROSS THE CAROLINAS. THE RIDGING ALOFT EXTENDED WESTWARD TO THE APPALACHIANS AND OHIO VALLEY REGION PER THE LATEST DATA. ONLY A FEW ISOLATED SHOWERS WERE ABLE TO DEVELOP THIS AFTERNOON OVER THE SANDHILLS REGION BUT EVEN THE COVERAGE IN THE WESTERN PART OF NC WAS SUPPRESSED TODAY. THIS WILL BE CHANGING IN THE COMING DAYS AS THE PLUME OF MOISTURE FROM TEXAS NE THROUGH THE TENNESSEE VALLEY INTO NEW ENGLAND SLOWLY SAGS SOUTHEAST. HOWEVER... THIS WILL NOT OCCUR UNTIL MONDAY. THEREFORE... YET ANOTHER WARM NIGHT WITH MODERATE HUMIDITIES CAN BE EXPECTED UNDER THE BERMUDA HIGH OVER OUR REGION. THE SKIES SHOULD BE MOSTLY CLEAR UNTIL VERY LATE TONIGHT AND SUNDAY MORNING WHEN PATCHY STRATUS AND STRATOCUMULUS SHOULD DEVELOP. MODELS SUGGEST THAT THE COVERAGE WILL BE LESS THAN IN PREVIOUS DAYS... GIVING INCREASED CONFIDENCE IN THE CLOUDINESS REMAINING SCATTERED. LOWS GENERALLY 63-68 AGAIN TONIGHT. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 240 PM SATURDAY... THE MONOTONOUS PATTERN CONTINUES ON SUNDAY WITH HIGH PRESSURE AND SOUTHERLY RETURN FLOW AGAIN THE THEME OF THE DAY IN ALMOST A CARBON COPY OF SATURDAY. ANY DIFFERENCES WOULD BE A SLIGHTLY EASTWARD SHIFT OF PRECIPITATION IN THE WEST...MEANING SLIGHTLY BETTER CHANCES FOR DIURNAL CONVECTION IN THE TRIAD. THEREFORE WILL CARRY CHANCE POPS IN THE NW PIEDMONT WITH SLIGHT CHANCE ELSEWHERE SUNDAY AFTERNOON AND THROUGH THE EVENING. OTHERWISE MORE OF THE SAME WITH TEMPS AGAIN IN THE MID TO UPPER 80S FOR HIGHS WITH LOWS IN THE MID TO UPPER 60S. FOG AND STRATUS WILL ONCE AGAIN BE A POSSIBILITY SUNDAY NIGHT INTO MONDAY MORNING BUT AGAIN...THE DETAILS REMAIN A LOW CONFIDENCE FORECAST. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 215 PM SATURDAY... A PATTERN CHANGE FROM THE RECENT WARM/DRY CONDITIONS IS ON THE WAY... AS THE WRN ATLANTIC RIDGE WILL FINALLY GIVE WAY TO A SOUTHWARD DIP IN THE WESTERLIES OVER THE CONUS. THIS WILL BRING IMPROVING CHANCES FOR MUCH-NEEDED RAINFALL BEGINNING EARLY IN THE WORK WEEK. THE VAST MAJORITY OF CENTRAL NC HAS SEEN VERY LITTLE RAIN IN THE LAST COUPLE OF WEEKS... 1 TO 2 INCHES BELOW NORMAL OR UNDER 50% OF NORMAL... IN THE LAST 14 DAYS ACCORDING TO WATER.WEATHER.GOV/PRECIP/. THE SURFACE FRONT SHOULD BE SITUATED ACROSS SRN PA DOWN THROUGH WRN WV AND ERN KY/TN EARLY MON AS THE MID LEVEL TROUGH EXTENDS FROM THE GREAT LAKES DOWN THROUGH THE LOWER MISS VALLEY. LEE TROUGHING WILL SHARPEN THROUGH THE PIEDMONT MON WITH INCREASING PW TO 150% OF NORMAL OR GREATER... LEADING TO RISING CHANCES FOR SHOWERS AND STORMS STARTING FIRST OVER THE WRN CWA BY EARLY AFTERNOON THEN DRIFTING EASTWARD. STEERING FLOW WILL BE QUITE WEAK WITH ONLY 10-15 KTS OF DEEP LAYER SHEAR... SO EXPECT A SLOW NE MOVEMENT TO THE CELLS. LARGE SCALE MODELS AND SREF PROBABILITIES SUGGEST SCATTERED SHOWERS/STORMS MAINLY ACROSS THE NRN/WRN CWA WITH ISOLATED CELLS IN THE SOUTHEAST ALONG THE INLAND-MOVING SEA BREEZE... SUPPORTING THE EXISTING FORECAST AND WILL LEAVE POPS LARGELY AS IS. SLIGHTLY ABOVE NORMAL THICKNESSES WITH PARTLY TO MOSTLY CLOUDY SKIES SHOULD LEAD TO HIGHS CLOSE TO NORMAL... MID-UPPER 80S AS THE THERMAL RIDGE EXTENDS THROUGH CENTRAL NC. MILD MON NIGHT WITH CONVECTIVE DEBRIS MID CLOUDS AND SOME STRATUS. CONVECTION COVERAGE WILL DWINDLE WITH LOSS OF HEATING BUT DEEPENING MOISTURE AND WEAK ELEVATED INSTABILITY NECESSITATES KEEPING IN AT LEAST ISOLATED COVERAGE MON NIGHT. HAVE UPPED MON NIGHT LOWS TO THE UPPER 60S-NEAR 70. THE MID LEVEL TROUGH WILL CONTINUE TO EASE EASTWARD TUE BUT WILL BECOME UNPHASED WITH THE FASTER NORTHERN PORTION CROSSING FAR SRN QUEBEC INTO THE NORTHEAST STATES WHILE THE SOUTHERN PORTION LAGS BACK OVER THE CENTRAL GULF STATES... POTENTIALLY CLOSING OFF. (THE ECMWF HAS TRENDED IN THIS DIRECTION BUT DEPARTS FROM THE NAM/GFS IN DIGGING THE NRN STREAM SEEMINGLY TOO MUCH OVER THE ERN LAKES/NORTHEAST STATES... WITH A TOO-FAST AND TOO-FAR SOUTHWARD FRONTAL MOVEMENT DOWN THROUGH THE MIDATLANTIC LATE TUE AND TUE NIGHT. FAVOR THE CONSISTENT SLOWER AND MORE-NORTHERN GFS. THIS WILL KEEP A LIGHT SSW STEERING FLOW OVER NC. ONCE THE MORNING STRATUS MIXES OUT... CONVECTION SHOULD BE SWIFT TO INITIATE WITH PLENTIFUL MOISTURE (PW 150-180% OF NORMAL)... INCLUDING WITHIN THE MIXED PHASE REGION ALOFT... AND MODERATE MUCAPE OF 1000-2000 J/KG. LIKELY MODE OF CONVECTION WILL BE MULTICELL CLUSTERS AND PULSE STORMS WITH DEEP LAYER SHEAR REMAINING MODEST AT JUST 15-25 KTS AND DEEP FAIRLY UNIDIRECTIONAL FLOW. EXPECT NUMEROUS SHOWERS/STORMS ALONG THE SURFACE TROUGH THROUGH THE PIEDMONT... AND THE SREF SHOWS THIS AS WELL WITH A 70-90% CHANCE OF MEASURABLE RAIN OVER THE ENTIRE AREA TUE AFTERNOON. WILL HAVE LIKELY POPS AREAWIDE... TRENDING DOWN SLIGHTLY AFTER NIGHTFALL BUT PERSISTING GIVEN LINGERING MARGINAL INSTABILITY. THE FRONT SHOULD DIP DOWN TO THE NC/VA LINE OVERNIGHT... PUSHING THE BEST COVERAGE TO THE S/E CWA... BUT DON`T EXPECT THE FAR-SOUTH PUSH OF THE ECMWF WHICH SUGGESTS LITTLE TO NO CHANCE IN THE NORTH OVERNIGHT. HIGHS TUE 82-87... WITH ABOVE NORMAL THICKNESSES ONCE AGAIN TEMPERED BY CLOUDS. LOWS TUE NIGHT MID-UPPER 60S. FORECAST CONFIDENCE SLIPS STARTING WED WITH INCREASING UNCERTAINTY AS TO WHETHER OR NOT A WEAK MID LEVEL LOW WILL CUT OFF... AND IF IT DOES... EXACTLY WHERE IT SETTLES. THE GFS/ECMWF WITH VARYING STRENGTH AND PLACEMENT KEEP IT TO OUR SSW OR SW... MEANDERING OVER THE SOUTHEAST OR GULF STATES... WITH WEAK MID LEVEL FLOW PERSISTING OVER NC. THE FRONT SHOULD DIP INTO THE NORTHEAST CWA WED... THEN WASH OUT GRADUALLY THE REST OF THE WEEK WHILE GIVING WAY TO AN INVERTED TROUGH JUST OFF THE SE COAST. PW IS LIKELY TO STAY ABOVE NORMAL WITH SOUPY LOW LEVEL AIR... GENERATING TYPICAL SCATTERED DAILY SHOWERS AND STORMS WED THROUGH SAT. THICKNESSES WILL RECOVER BACK TO ABOVE NORMAL VALUES BY FRI/SAT. EXPECT HIGHS IN THE LOW-MID 80S WED TO RISE GRADUALLY EACH DAY... REACHING THE UPPER 80S BY SAT. LOWS IN THE LOW-MID 60S WARMING TO THE UPPER 60S SAT MORNING. -GIH && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... AS OF 700 PM SATURDAY... 24-HR TAF PERIOD: ASIDE FROM A POTENTIAL FOR SUB-VFR CONDITIONS DURING THE EARLY MORNING HOURS (09-15Z)...CEILINGS AT THE INT/GSO TERMINALS AND FOG AT THE RWI TERMINAL...VFR CONDITIONS WILL PREVAIL THROUGH EARLY SUNDAY AFTERNOON. ISOLD SHOWERS/STORMS WILL BE POSSIBLE BY MID/LATE SUNDAY AFTERNOON...PRIMARILY AT THE INT/GSO TERMINALS. LOOKING AHEAD: CHANCES FOR EARLY MORNING STRATUS/FOG AND AFT/EVE CONVECTION WILL INCREASE AT ALL TERMINALS MON-WED AS A SLOW-MOVING UPPER LEVEL TROUGH APPROACHES THE CAROLINAS/MID-ATLANTIC FROM THE WEST. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT/ELLIS SHORT TERM...ELLIS LONG TERM...HARTFIELD AVIATION...VINCENT

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