Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 281816 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 115 PM EST FRI NOV 28 2014 .SYNOPSIS...HIGH PRESSURE WILL BUILD OVER THE REGION FROM THE WEST TODAY...AND SETTLE OVERHEAD TONIGHT AND SATURDAY. THE HIGH WILL DRIFT OFFSHORE BY SUNDAY RESULTING IN A WARM SOUTHWEST FLOW OVER OUR AREA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1005 AM FRIDAY... FOR THE REST OF TODAY...HIGH PRESSURE CENTERED OVER THE TN VALLEY AT 14Z WILL DRIFT EAST ACROSS THE CAROLINAS TODAY. MEANWHILE...MORNING UPPER AIR ANALYSIS AND GSO SOUNDING SHOWS FAIRLY DEEP NW FLOW AND RISING HEIGHTS AS THE TROUGH AXIS OFF THE EAST COAST CONTINUES MOVING EASTWARD. THIS PATTERN SETS US UP FOR FAIR WEATHER TODAY... ALBEIT CHILLY WITH WELL BELOW NORMAL TEMPS...AS SUGGESTED BY 12Z 850MB TEMP AT GSO OF -9C... WHICH IS ABOUT 2 SD BELOW THE CLIMO MEAN. GIVEN THIS AIRMASS...HIGH TEMPS STILL LOOK ON-TRACK TO ONLY MAKE IT TO THE MID 40S. OTHERWISE...MODELS SUGGEST THAT THE SCATTERED MID-LEVEL CLOUDS CURRENTLY OVER KY/TN WILL DRIFT EAST ACROSS OUR AREA DURING THE AFTERNOON...SO SUNNY SKIES NOW WILL BECOME PC AS THE DAY GOES ON. TONIGHT...LOW LEVELS WILL REMAIN DRY AND COOL AS SURFACE HIGH WILL BE OVERHEAD. ALOFT...PATCHY CLOUDINESS MAY DRIFT OVERHEAD AS A SERIES OF WEAK PERTURBATIONS CROSS THE REGION. GFS MORE AGGRESSIVE WITH THE CLOUDINESS VERSUS THE NAM/CANADIAN/ECMWF. WILL TREND SKY COVERAGE TO PARTLY CLOUDY. CHILLY WITH MIN TEMPS IN THE MID-UPPER 20S. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 300 AM FRIDAY... SATURDAY AND SATURDAY NIGHT...AIR MASS MODIFICATION GETS UNDERWAY AS SURFACE HIGH DRIFTS EAST AND 850MB FLOW BECOMES SWLY. THICKNESSES RESPOND BY RECOVERING INTO THE 1330-1334M RANGE...SLIGHTLY BELOW NORMAL. ASIDE FROM BRIEF PERIODS OF MID-LEVEL CLOUDINESS...EXPECT MOSTLY SUNNY SKIES SATURDAY AND CLEAR SKIES SATURDAY NIGHT. HIGH TEMPS LOW-MID 50S WHILE MIN TEMPS SATURDAY NIGHT IN THE LOW-MID 30S. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 315 AM FRIDAY... SUNDAY THROUGH MONDAY: SEASONABLY WARM AND DRY CONDITIONS ARE EXPECTED FOR SUNDAY INTO MONDAY... WITH SURFACE HIGH PRESSURE OFF THE SOUTHEAST U.S. COAST AND A MID LEVEL RIDGE CENTERED TO THE SOUTH OF THE AREA... NEAR FL/OFF THE SOUTHEAST U.S. COAST. MOSTLY SUNNY/MOSTLY CLEAR CONDITIONS ARE EXPECTED DURING THIS TIME FRAME... OUTSIDE OF POSSIBLY SOME PRE-DAWN FOG AND/OR MORNING STRATUS ON MONDAY MORNING. A COLD FRONT WILL APPROACH THE AREA LATE IN THE DAY ON MONDAY FROM THE NORTH-NORTHWEST. HOWEVER... ANY CLOUD COVER ASSOCIATED WITH THE APPROACHING FRONT WILL GENERALLY HOLD OFF UNTIL VERY LATE IN THE DAY/EVENING... AS THERE WILL BE VERY LITTLE MOISTURE RETURN IN ADVANCE OF THE FRONT... WITH GENERALLY WESTERLY FLOW PRECEDING THE FRONT. TEMPS ON SUNDAY WILL CONTINUE THE WARMING TREND... WITH HIGHS EXPECTED TO BE IN THE 60S. A SIMILAR TREND WILL FOLLOW ON MONDAY. HOWEVER... GFS BUFR SOUNDINGS CONTINUE TO INDICATE A RATHER SHALLOW MIXED LAYER. THUS... POSSIBLY NOT REALIZING FULL SUN HIGHS WITH THE LOCAL THICKNESS SCHEME (ALSO THE CASE FOR SUNDAY`S HIGHS). NONETHELESS... WE STILL EXPECT TO SEE TEMPS CLIMB INTO THE MID TO UPPER 60S... WITH SOME LOW 70S SOUTH. LOW TEMPS ON MONDAY MORNING ARE EXPECTED TO BE IN THE 40S. MONDAY NIGHT THROUGH THURSDAY: THE AFOREMENTIONED COLD FRONT WILL SINK SOUTHWARD THROUGH THE AREA... PROPELLED BY A 1040+ MB SURFACE HIGH TO THE NORTH/NORTHWEST. MODELS CONTINUE TO INDICATE THE POTENTIAL FOR SOME PRECIP TO DEVELOP BEHIND THE FRONT WITH A DAMMING AIRMASS DEVELOPING. THE GFS CONTINUE TO BE FURTHER SOUTH WITH ITS INITIAL PLACEMENT OF THE SURFACE HIGH TO THE NORTH OF THE AREA VS THE ECMWF (GFS... CENTERED OVER NEW ENGLAND BY TUESDAY). EITHER WAY THIS WILL BUT AN ABRUPT END TO THE WARMTH. IN FACT... TEMPS MAY STRUGGLE TO REACH 40 ON TUESDAY IN THE NORTHWEST PIEDMONT AFTER EARLY TUESDAY MORNING (COULD SEE AN EARLY MORNING HIGH TEMP ON TUESDAY... DEPENDING ON HOW FAST SOME LIGHT PRECIP DEVELOPS). FOR NOW WILL GO RATHER CONSERVATIVE AND JUST LOWER TEMPS TO THE COLD SIDE OF STATISTICAL GUIDANCE (TOWARDS THE GFS STATISTICAL GUIDANCE). WHILE IT DOESNT LOOK LIKE WE WILL SEE A LOT OF PRECIP WITH THIS SYSTEM... WE WILL NEED TO KEEP AND EYE ON THE PARTIAL THICKNESS VALUES... AS THE LATEST GFS IS INDICATING THE POTENTIAL FOR SOME FREEZING RAIN/FREEZING DRIZZLE ACROSS THE NORTHWEST PIEDMONT ON TUESDAY MORNING... WITH ANY LINGERING FREEZING RAIN THREAT ENDING BY AT LEAST TUESDAY AFTERNOON AS THE SURFACE HIGH BEGINS TO SHIFT OFFSHORE... ENDING/WEAKENING THE NEEDED SUPPLY OF COLD DRY AIR TO OFFSET THE LATENT HEAT RELEASE CREATED BY PHASE CHANGE. WE ARE STILL A WAYS OUT IN THE FORECAST THOUGH... SO WILL KEEP EVERYTHING LIQUID FOR NOW AND TEMPS ABOVE FREEZING (WHICH IS WHAT THE LATEST ECMWF HAS... A COLD RAIN). LOWS TUESDAY MORNING FOR NOW IN THE MID 30S N/NW TO LOWER 40S SE. HIGHS TUESDAY... *FOR NOW*... RANGING FROM THE LOWER 40S NW TO LOWER TO MID 50S SE. THE STRONG SURFACE HIGH WILL QUICKLY SHIFT EASTWARD OFF THE NORTHEAST U.S. COAST/SOUTHEAST CANADIAN COAST ON TUESDAY NIGHT/WEDNESDAY MORNING AS THE NEXT SYSTEM QUICKLY APPROACHES FROM THE WEST. NOT SURE HOW MUCH WE WILL SEE THE CAD AIRMASS ERODE BEFORE IT IS SCOURED OUT WITH THE PASSAGE OF A COLD FRONT ON WEDNESDAY NIGHT. FOR NOW WILL ONLY LOWER TEMPS SLIGHTLY AND SHOW HIGHS RANGING FROM AROUND 50 NW TO LOWER 60S SE ON WEDNESDAY. THE THREAT FOR ANY PRECIP WILL END WITH THE FRONTAL PASSAGE... WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA FROM THE NORTHWEST. LOWS WEDNESDAY MORNING WILL DRIVEN BY THE CAD... LOWS WILL LIKELY OCCUR EARLY ON IN THE OVERNIGHT PERIOD... WITH SLOWLY RISING OR NEAR STEADY TEMPS. FOR NOW WILL NOT SHOW THIS MUCH DETAIL IN THE FORECAST THIS FAR OUT THOUGH. WILL SHOW LOWS IN THE 30S TO LOWER 40S FOR NOW... WITH A USUAL DIURNAL TREND. LOWS THURSDAY MORNING BEHIND THE COLD FRONT ARE EXPECTED TO BE IN THE UPPER 30S TO LOWER 40S. WITH A RETURN TO AT LEAST PARTLY SUNNY SKIES FOR 1THURSDAY. EXPECT HIGHS WILL BE IN THE 50S. && .AVIATION /18Z FRIDAY THROUGH TUESDAY/... AS OF 115 PM FRIDAY... HIGH PRESSURE OVER THE REGION WILL PROVIDE FAIR WEATHER AND VFR FLIGHT CONDITIONS THROUGH THE TAF PERIOD. LIGHT NW SFC WIND ATTM WILL BECOME VARIABLE THIS EVENING AND OVERNIGHT...THEN BECOME S TO SW AROUND 10 KT ON SATURDAY AS THE HIGH CENTER SHIFTS TOWARD THE COAST. THE CHANCE FOR SOME FOG OR STRATUS WILL INCREASE SUNDAY AND MONDAY MORNINGS AS SOUTHERLY FLOW INCREASES WITH THE HIGH SHIFTING OFFSHORE. OTHERWISE...THE NEXT CHANCE FOR PRECIP THAT MAY IMPACT FLIGHT CONDITIONS WILL BE ON MONDAY NIGHT INTO TUESDAY ASSOCIATED WITH THE NEXT COLD FRONT. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...NP/WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...NP

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