Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 230226 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1026 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/... AS OF 1020 PM MONDAY... TONIGHT: A SHORTWAVE TROUGH THAT PRODUCED 70 METER H5 HEIGHT FALLS AT FFC THIS EVENING WILL CONTINUE TO EVOLVE INTO A CUT-OFF LOW OVER THE CAROLINAS THROUGH THE NEXT 36-48 HOURS. SPRINKLES OR BARELY MEASURABLE LIGHT RAIN...ONES FALLING FROM MID LEVEL CEILINGS...WILL RESULT THROUGH SUNRISE FROM THE SOUTHERN PIEDMONT AND SANDHILLS TO THE SOUTHERN AND CENTRAL COASTAL PLAIN. CONSIDERABLE MID-HIGH CLOUDINESS WILL PREVAIL OTHERWISE AND ELSEWHERE TONIGHT. WHILE BOTH PROXIMITY RAOB AND VWP DATA INDICATE LOW LEVEL FLOW HAS MAINTAINED A NORTHERLY COMPONENT THIS AFTERNOON AND EVENING...THESE WINDS ARE FORECAST TO ASSUME AN EASTERLY COMPONENT EARLY TUE...AT WHICH TIME LOWER LEVEL MOISTURE FORCING WILL SUPPORT A GOOD TO LIKELY PROBABILITY OF RAIN ACROSS THE FAR SOUTHEASTERN RAH CWFA. PREVIOUS NEAR TERM DISCUSSION... 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. && .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 /00Z TUESDAY THROUGH SATURDAY/... AS OF 730 PM MONDAY... VFR CONDITIONS ARE LIKELY TO DOMINATE AT ALL CENTRAL NC TERMINAL FORECAST SITES THROUGH TUE. A STALLED FRONTAL ZONE JUST SOUTHEAST OF CENTRAL NC... COMBINED WITH AN UPPER LEVEL LOW PRESSURE AREA DEVELOPING OVERHEAD... WILL PROVIDE A FOCUS FOR BOUTS OF LIGHT RAIN NEAR FAY... PRIMARILY THIS EVENING AND AGAIN TOWARD DAYBREAK TUE. VSBYS MAY BRIEFLY DIP TO MVFR WITHIN THIS LIGHT RAIN... HOWEVER THE VAST MAJORITY OF THE TIME... BOTH CIGS AND VSBYS AT FAY WILL STAY VFR... DESPITE THE LIGHT RAIN. OTHERWISE... AT INT/GSO/RDU/RWI... COOL HIGH PRESSURE RIDGING IN FROM THE NORTH WILL PROVIDE ENOUGH OF A PUSH OF LOW LEVEL DRY AIR TO HOLD ANY PRECIP AND SUB-VFR CLOUDS/VSBYS OUT OF THESE TAF SITES THROUGH TUE AFTERNOON. EXPECT SURFACE WINDS TO HOLD OUT OF THE NORTHEAST UNDER 8 KTS TONIGHT AND 8- 12 KTS ON TUE. LOOKING BEYOND 00Z WED... UNCERTAINTY GROWS STARTING TUE EVENING... AS IT IS NOT CLEAR HOW FAR INLAND THE COASTAL RAINFALL WILL MOVE. BUT THE MOST LIKELY SCENARIO IS FOR SOME INLAND PENETRATION OF LIGHT RAIN OVER THE FAY/RWI/RDU AREAS TUE NIGHT THROUGH WED. MVFR CIGS ARE POSSIBLE AT FAY TUE NIGHT/WED... BUT ARE MUCH LESS LIKELY AT RDU/RWI. THERE IS A MUCH BETTER CHANCE OF MVFR OR IFR CIGS WED EVENING/NIGHT AS NEAR-SURFACE MOISTURE INCREASES. CIGS SHOULD REBOUND TO VFR THU... DOMINATING THROUGH SAT AS THE UPPER LEVEL LOW OVER THE REGION WEAKENS AND LIFTS TO OUR NORTHEAST. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...MWS/CBL SHORT TERM...KRD LONG TERM...KRD AVIATION...HARTFIELD

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