Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 221929 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 330 PM EDT MON SEP 22 2014 .SYNOPSIS...AN UPPER LEVEL LOW WILL DEVELOP OVER THE CAROLINAS TONIGHT...AND WILL SLOWLY WEAKEN OVER THE REGION THROUGH MID-WEEK. MEANWHILE...AT THE SURFACE...A STALLED FRONT WILL LINGER ALONG THE SOUTHEAST COAST AS HIGH PRESSURE EXTENDS INTO THE AREA FROM THE NORTH. && .NEAR TERM /THROUGH TUESDAY NIGHT/...
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AS OF 330 PM MONDAY... STRONG SHORTWAVE DIVING SE OVER THE SOUTHERN APPALACHIANS WILL DECELERATE AND WILL CLOSE AND EVENTUALLY BECOME CUT-OFF OVER THE CAROLINAS TONIGHT THROUGH TUESDAY NIGHT...GRADUALLY SHEARING DURING THE PERIOD. IN RESPONSE...SURFACE COLD FRONT WILL STALL OUT ALONG THE COAST AS HIGH PRESSURE TO OUR NORTH NOSES SOUTH INTO THE CAROLINAS. EVEN THE NEAR TERM PERIOD HAS SLIDE TO UNAVOIDABLE OBSCURITY AS MODEL SPREAD REMAINS HIGH BEGINNING AS EARLY AS LATE TONIGHT- TUESDAY. THE GFS WHICH HAD BEEN CONSISTENTLY ON THE DRIER SIDE OF THE MODEL SPECTRUM...IS NOW THE WETTER/MORE AMPLIFIED SOLUTION. GIVEN THAT THE ECMWF REMAINS THE MOST CONSISTENT SOLUTION OVER THE LAST COUPLE OF DAYS...THE EC WILL BE RELIED ON HEAVILY FOR THE NEAR TERM FORECAST. RAIN CHANCES: RAIN WILL ATTEMPT TO SPREAD INLAND ACROSS THE SOUTHERN COASTAL PLAIN (SAMPSON/WAYNE COUNTIES)LATE TONIGHT... AND THROUGH THE DAY ON TUESDAY...BUT EVEN MORE SO TUESDAY NIGHT VIA STRENGTHENING LOW-LEVEL EASTERLY MOISTURE TRANSPORT IN RESPONSE TO WEAK WAVE DEVELOPMENT ALONG THE COASTAL INVERTED TROUGH AND UNDER THE INCREASING UPPER DIFFLUENCE MAXIMA ON THE EAST SIDE OF THE UPPER LOW. IF THE GFS IS CORRECT...PRECIP COULD DEVELOP WELL INLAND AND MUCH FASTER THAN FORECAST REFLECTS...BUT FOR NOW WILL GO WITH THE SLOWER TIMING OF THE EC. TEMPERATURES: LOW TEMPERATURES THE NEXT TWO NIGHTS WILL NOT BE QUITE AS COOL AS ORIGINALLY THOUGHT OWING TO THE RETURN OF CLOUDS. LOWS RANGING FROM LOWER 50S N/NW PIEDMONT TO UPPER 50S/NEAR 60 SOUTHEAST. HIGHS TUESDAY NEAR 70.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 230 PM MONDAY... FORECAST CONFIDENCE REMAINS SOMEWHAT BELOW NORMAL FOR THE MIDDLE OF THE WEEK AS THERE CONTINUES TO BE SOME DISAGREEMENT AMONG THE MODELS...ALTHOUGH THERE IS SOME MODEL CONVERGENCE TOWARDS A MORE UNSETTLED PERIOD. THE LOW LEVEL FLOW AROUND THE HIGH WILL INCREASE AND BEGIN TO GRADUALLY TAKE ON MORE OF AN EAST OF NORTHERLY COMPONENT (AS HIGH PRESSURE SHIFTS OFF THE NORTHEAST COAST) ALLOWING MOISTURE TO RETURN TO THE AREA. IN ADDITION...MODELS CONTINUE TO HINT AT A WEAKNESS ALOFT AND ASSOCIATED INVERTED TROUGH DEVELOPING NEAR THE SOUTHEAST COAST (ALTHOUGH TO VARYING DEGREES AMONG THE MODELS). THIS WOULD INCREASE CLOUDS AND PRECIP CHANCES (ESPECIALLY ACROSS EASTERN NC). THE MORE CONSISTENT ECMWF SHOWS A CLOSED LOW ALOFT ACROSS THE SOUTHEAST WHICH IN TURN RESULTS IN A STRONGER INVERTED TROUGH AND THEREFORE MORE ENHANCED PRECIP/CLOUD COVER. THE GFS NOW ALSO SHOWS A CLOSED LOW ALOFT OVER THE AREA...BUT IT IS FURTHER OFFSHORE (AND MORE PROGRESSIVE) WITH THE INVERTED TROUGH...THUS IT IS STILL THE DRIER SOLUTION. WILL CONTINUE TO FOLLOW MORE CLOSELY TO THE MORE CONSISTENT ECMWF (AND EC ENSEMBLE MEAN). REGARDLESS...CLOUDY AND COOLER CONDITIONS WILL PERSIST... WITH RAIN CHANCES INCREASING (ESPECIALLY ACROSS THE EAST). HIGHS ARE EXPECTED TO STAY IN THE LOW TO MID 70S (WITH SOME UPPER 60S POSSIBLE) AND OVERNIGHT LOWS MOSTLY IN THE MID/UPPER 50S TO LOWER 60S. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 230 PM MONDAY... SOME DRYING IS EXPECTED BEGINNING FRIDAY...BUT ESPECIALLY INTO THE WEEKEND AS THE UPPER LOW FILLS IN WHILE RIDGING TRIES TO BUILD EAST. THIS WILL CAUSE THE INVERTED TROUGH TO WEAKEN/DISSIPATE. HOWEVER... WILL NOT REMOVE POPS ALTOGETHER AS THERE WILL BE STILL BE A WEAKNESS ALOFT OVER THE AREA AND MOISTURE WILL NOT DECREASE SIGNIFICANTLY. WITH THE ABOVE IN MIND...TEMPS WILL UNDERGO SOME MODERATION...AND ARE EXPECTED TO RETURN TO NEAR NORMAL VALUES. OUR NEXT SYSTEM MAY APPROACH THE AREA EARLY NEXT WEEK...BUT AS CAN BE EXPECTED (GIVEN THE LOW CONFIDENCE IN THE MEDIUM RANGE FORECAST)...THERE IS A LOT OF UNCERTAINTY IN THE EXTENDED RANGE. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 205 PM MONDAY... 24-HR TAF PERIOD: DRY LOW-LEVEL AIR FILTERING IN THE AREA FROM THE NORTH...IN THE WAKE OF THIS MORNINGS COLD FRONTAL PASSAGE WILL SECURE VFR CONDITIONS THROUGH THE PERIOD. THE FRONT WILL STALL JUST OFFSHORE...ALONG THE SOUTHEAST COAST TONIGHT THROUGH MID-WEEK AS CLOSED/CUT-OFF LOW DEVELOPS OVER THE CAROLINAS. THIS WILL SPREAD MOISTURE IN THE 5-10KFT LAYER BACK INLAND TONIGHT THROUGH TUESDAY WITH INCREASING RAIN CHANCES ACROSS THE SOUTHEAST...AND POSSIBLY EASTERN/CENTRAL PIEDMONT. WINDS SHOULD REMAIN OUT OF THE NORTH AT 5-10KT THROUGH THE PERIOD. LOOKING AHEAD: PROXIMITY TO CUT-OFF UPPER LOW OVER THE CAROLINAS ALONG WITH INVERTED SFC TROUGH ALONG THE COAST WILL LIKELY RESULT IN A CONTINUATION OF BROKEN TO OVERCAST CLOUD COVER WITH BETTER RAIN CHANCES EXPECTED ALONG THE SOUTHEAST NEAR KFAY WITH THE POTENTIAL FOR SOME SUB-VFR CEILINGS TUESDAY NIGHT AND INTO WEDNESDAY. ELSEWHERE...VFR CONDITIONS ARE LIKELY TO PREVAIL FURTHER INLAND OVER CENTRAL NC AS DRY AIR SURFACE RIDGE EXTENDS SOUTH INTO PIEDMONT. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...KRD LONG TERM...KRD AVIATION...CBL

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