Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 011910 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 210 PM EST SUN MAR 1 2015 .SYNOPSIS...A DISTURBANCE WILL EXIT THE REGION BY THIS EVENING. WEAK BUT COOL HIGH PRESSURE WILL HOLD OVER THE AREA THROUGH TONIGHT. A COLD FRONT WILL PUSH SOUTHWARD THROUGH NORTH CAROLINA ON MONDAY... THEN SETTLE JUST TO OUR SOUTH MONDAY NIGHT AS HIGH PRESSURE NOSES IN FROM THE NORTH. MOIST AIR RIDING UP AND OVER THIS STATIONARY FRONT WILL BRING UNSETTLED WEATHER FOR TUESDAY INTO WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... AS OF 210 PM SUNDAY... THROUGH TONIGHT: FAIRLY DEEP MOIST ISENTROPIC UPGLIDE ATOP A CHILLY IN SITU WEDGE AIR MASS CONTINUES TO PRODUCE AREAS OF LIGHT RAIN AND DRIZZLE OVER CENTRAL NC. THE LOSS OF A FEED OF LOW LEVEL DRY AIR IN TO THE AREA TO COUNTERACT THE EFFECTS OF LATENT HEAT RELEASE HAS LED TO A SWITCHOVER TO MOSTLY FREEZING RAIN OVER ALL BUT THE FAR NORTHERN PIEDMONT... AND EVEN HERE IT DOESN`T APPEAR THAT ANY ADDITIONAL ICE IS ACCRUING GIVEN THE NEAR-FREEZING WET BULBS. TRENDS ALL SUGGEST THAT WE CAN LET WHAT`S LEFT OF THE ADVISORY EXPIRE ON SCHEDULE OR PERHAPS BE CANCELLED A BIT EARLY. THE SUPPORTIVE MOIST UPGLIDE WILL BE ON THE WANE THROUGH THE LATE AFTERNOON AND EARLY EVENING... AS THE WEAK 850 MB WAVE HEADS TO OUR NORTHEAST... AND MODEL GUIDANCE ALL POINT TO AN EXIT OF THE RAIN TO THE NORTHEAST THIS EVENING. WILL MAINTAIN A WEST-TO-EAST TAPERING OFF OF POPS ACROSS THE CWA. A WEAK SURFACE MESOHIGH WILL HOLD OVER THE WESTERN AND CENTRAL CAROLINAS OVERNIGHT... WITH A WEAK REMNANT COASTAL FRONT ON ITS EASTERN EDGE AND THE MOUNTAINS ON ITS WESTERN EDGE HINDERING ANY HORIZONTAL DISPERSION... AND A CONTINUED STABILIZING WARM SURGE ALOFT PREVENTING VERTICAL DISPERSION. EXPECT LOW CLOUDS AND FOG TO HOLD TONIGHT WITH HIGHLY STABLE AND MOIST LOW LEVELS. THIS PATTERN AS WELL AS STATISTICAL GUIDANCE SUPPORT TEMPS MOVING VERY LITTLE OVERNIGHT... HOLDING AT ROUGHLY 32 TO 40. TOO MUCH UNCERTAINTY RIGHT NOW REGARDING STRATUS VERSUS FOG DOMINATING TONIGHT... BUT IF OUR SURFACE WINDS DROP TO LESS THAN 4 KTS FOR AN EXTENDED TIME... WE MAY NEED A DENSE FOG ADVISORY FOR A PORTION OF THE CWA OVERNIGHT. FOR MON/MON NIGHT: A POTENT NORTHERN STREAM SHORTWAVE TROUGH CROSSING THE GREAT LAKES/ST LAWRENCE VALLEY/NORTHEAST LATE TONIGHT/MONDAY WILL HELP PUSH A WEAK FRONT SOUTHWARD INTO AND THROUGH NC MONDAY... AND AFTER A MURKY AND GRAY MONDAY MORNING... THIS MECHANISM WILL FINALLY SCOUR OUT THE LOW LEVEL MOIST/STABLE POOL FROM NNW TO SSE DURING THE DAY. MODELS DEPICT ENOUGH LOW AND MID LEVEL MOISTURE HOLDING ON OVER SRN NC NEAR THE SOUTHWARD-INCHING FRONTAL ZONE WITH SUFFICIENT LINGERING LOW LEVEL MOISTURE TRANSPORT TO SUPPORT A LOW CHANCE OF SOME PATCHY LIGHT RAIN OVER THE SRN CWA MON FROM LATE MORNING THROUGH MID AFTERNOON... WHILE FURTHER NORTH... WE SHOULD TREND TOWARD PARTIAL CLEARING AS DRIER LOW LEVEL AIR ATTEMPTS TO BUILD IN. HAVE OPTED TO STAY ON THE LOW END OF GUIDANCE FOR HIGHS MONDAY (NEAR 50 NORTH TO THE UPPER 50S SOUTH) AS THERE IS LIKELY TO BE A DELAY AND LIMIT TO THE PARTIAL CLEARING... HOWEVER IF LATER FORECASTS TREND TOWARD MORE SUNSHINE TOMORROW... THESE MAY NEED TO BE BUMPED UP A CATEGORY OR SO. THE RELATIVELY QUIET WEATHER WILL BE SHORT-LIVED... NOT A SURPRISE GIVEN THE STRONG JET LEVEL WINDS OVER THE CENTRAL/SRN CONUS FOSTERING AN ACTIVE WEATHER CYCLE. AN APPROACHING WEAK LOW LEVEL WAVE AND PRECEDING SURGE IN MOISTURE TRANSPORT INTO THE MIDSOUTH AND SOUTHERN APPALACHIANS WILL SUPPORT A SMALL CHANCE POP IN THE SW CWA LATE MON NIGHT. LOWS FROM AROUND 30 NE TO MID-UPPER 30S FAR SOUTHWEST. -GIH && .SHORT TERM / /... AS OF 345 AM SUNDAY... TO BE UPDATED. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 320 PM SUNDAY... TUESDAY: SURFACE HIGH PRESSURE LOCATED JUST TO THE NORTH OF CENTRAL NC AND AND MID LEVEL RIDGING EXTENDING INTO THE AREA FROM THE SOUTH WILL BOTH QUICKLY SHIFT EASTWARD ON TUESDAY. HOWEVER... THE LINGERING COLD DRY SURFACE AIR DEPOSITED BY THE SURFACE HIGH WILL AGAIN SET THE STAGE FOR AN INSITU CAD EVENT ON TUESDAY INTO TUESDAY NIGHT... POSSIBLY LINGERING INTO WEDNESDAY MORNING ACROSS THE FAR NORTHWEST PIEDMONT. WARM MOIST AIR WILL INCREASING IN SOUTHERLY TO SOUTHWESTERLY FLOW ALOFT. GIVEN THIS AND THE LINGERING COLD SURFACE AIRMASS... WE SHOULD SEE SOME ISENTROPICALLY DRIVEN PRECIP DEVELOP TUESDAY MORNING INTO THE AFTERNOON. MODELS CONTINUE TO BRING THE LIGHT PRECIP IN AFTER SURFACE TEMPS AND DEWPOINTS INCREASE ENOUGH TO AVOID AND NUISANCE FREEZING RAIN. HOWEVER... HIGH TEMPS WILL BE WELL BELOW NORMAL AND GREATLY AFFECTED BY THE CAD AIRMASS. MAV STATISTICAL GUIDANCE APPEARS TO BE WAY TOO WARM FOR TUESDAY... WITH THE RAW GFS TEMPS CLOSER TO MET GUIDANCE VALUES. FOR NOW WILL LOWER TEMPS FURTHER... AND THIS MAY NOT EVEN BE FAR ENOUGH. WILL WO WITH HIGH TEMPS RANGING FROM THE UPPER 30S NORTH TO NEAR 50 IN THE FAR SOUTHEAST. TUESDAY NIGHT THROUGH THURSDAY NIGHT: ANOTHER STRONG ARCTIC COLD FRONT WILL APPROACH THE REGION ON TUESDAY NIGHT... BEFORE SLOWLY MOVING ACROSS THE AREA WEDNESDAY INTO THURSDAY MORNING. THE FRONT IS EXPECTED TO BECOME PARALLE WITH THE MID LEVEL FLOW AS THE MID/UPPER LEVEL TROUGH BECOMES MORE OF A FULL LATITUDE TROUGH... WHICH APPEARS TO PHASE SOME THE THE SOUTHERN STREAM ENERGY WITH THE NORTHERN STREAM... RESULTING IN A DEEP FETCH OF SOUTHWESTERLY MID LEVEL FLOW... ALONG WITH SEVERAL SURFACE LOWS TRACKING ALONG THE FRONT FROM TIME TO TIME. MOST OF THE SHOWERS WILL BE ALONG AND BEHIND THE FRONT... MAINLY FROM WEDNESDAY MID-MORNING INTO THE AFTERNOON UNTIL LATE THURSDAY (WITH A GOOD CHANCE OF PRECIP... POSSIBLY SOME HEAVY AMOUNTS OF RAIN). IN ADDITION... MODELS HAVE TRENDED FASTER WITH SURGING THE STRONG/DEEP COLD LOW LEVEL AIRMASS INTO THE REGION. IF THIS WERE TO OCCUR... WE COULD POSSIBLE SEE SOME WINTRY P-TYPES ON THURSDAY. HOWEVER... GIVEN WE ARE STILL TALKING ABOUT DAY 5 IN THE FORECAST AND WE ARE NOW IN THE MONTH OF MARCH... WILL WAIT TO ADD ANY NON-LIQUID P-TYPE TO THE FORECAST. DRY WEATHER IS EXPECTED TO RETURN FOR AT LEAST FRIDAY. HOWEVER... THE SYNOPTIC PATTERN MAY REMAIN CONDUCIVE FOR WAVES OF LOW PRESSURE TO DEVELOP AND TRACK ALONG THE FRONT... WHICH IS EXPECTED TO BE LOCATED OFF THE CAROLINA COAST LATE WEEK INTO THE WEEKEND. THUS... WE COULD CONCEIVABLY SEE SOME PRECIP IF ONE SUCH SYSTEM DEVELOPS NEXT WEEKEND. TEMPS DURING THE MEDIUM RANGE WILL INCLUDE SOME DECENT SWINGS... WITH HIGHS TEMPS WEDNESDAY IN THE 60S AND 70S... THURSDAY 40S AND 50S (MAYBE COLDER)... WITH FRIDAY BACK IN THE 40S (WITH MAYBE SOME 30S EVEN). WE WILL SEE SOME MODERATING BY SATURDAY... GENERALLY BACK INTO THE 50S... GIVEN WE REAMIN DRY. LOWS WILL FOLLOW A SIMILAR PATTERN. AS MENTIONED ABOVE... ALL PRECIP AS OF NOW APPEARS TO BE IN THE FORM OF LIQUID FOR THE MEDIUM RANGE... OUTSIDE OF *MAYBE* A BRIEF PERIOD AS THE PRECIP ENDS ON THURSDAY. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 1245 PM SUNDAY... PRIMARY AVIATION CONCERNS NEXT 24 HRS: CONTINUED IFR/LIFR CIGS AND MVFR/IFR VSBYS THROUGH TONIGHT... AND BORDERLINE LOW LEVEL WIND SHEAR THIS EVENING/TONIGHT. WIDESPREAD IFR/LIFR CONDITIONS PERSIST OVER CENTRAL NC TAF SITES THIS AFTERNOON... ALONG WITH PATCHES OF RAIN (FAY/RDU) OR FREEZING RAIN (RWI/INT/GSO). THIS FREEZING RAIN AT RWI/INT/GSO WILL TREND TO JUST RAIN THIS AFTERNOON... FIRST AT RWI THEN AT GSO AND INT. ALL LOCATIONS SHOULD BE JUST RAIN BEFORE 21Z. PERIODS OF RAIN WILL TAPER OFF AT INT/GSO BY 22Z THIS AFTERNOON... AT RDU BY 00Z THIS EVENING... AND AT FAY/RWI BY 04Z LATE THIS EVENING. WITH FAIRLY LIGHT SURFACE WINDS OVERNIGHT AND A MOIST GROUND... CONFIDENCE IS HIGH THAT IFR/LIFR CONDITIONS WILL HOLD THROUGH AT LEAST 12Z MON AT ALL TAF SITES. AS A WEAK FRONT DROPS SOUTHEAST INTO THE AREA MONDAY... CAUSING SURFACE WINDS TO SHIFT FROM LIGHT SW TO BE FROM THE NW... THESE LOW CLOUDS/FOG WILL SCOUR OUT GRADUALLY TO VFR BY THE 16Z-18Z MONDAY TIME FRAME AT INT/GSO... WITH LOWER CONFIDENCE IN THIS OCCURRING PRIOR TO 18Z AT RDU/RWI/FAY. LOW LEVEL WIND SHEAR THREAT REMAINS MARGINAL AND FOCUSED AFTER MIDNIGHT TONIGHT AT FAY/RDU/RWI... AS 1000-1500 FT AGL WINDS BECOME WESTERLY AT 25-30 KTS. LOOKING BEYOND 18Z MON... VFR CONDITIONS SHOULD PERSIST FROM EARLY TO MID AFTERNOON MONDAY THROUGH MONDAY NIGHT... AS THE SURFACE FRONT SETTLES ALONG THE SRN NC BORDER WHILE HIGH PRESSURE NOSES IN FROM THE NORTHWEST. HOWEVER... A DISTURBANCE ALOFT RIDING ALONG THE SURFACE FRONT WILL BRING A THREAT OF MVFR/IFR CONDITIONS STARTING LATE MONDAY NIGHT (INT/GSO) OR TUE AFTERNOON (RDU/RWI/FAY)... ALONG WITH A LLWS RISK. THESE SUB-VFR CONDITIONS SHOULD GIVE WAY TO VFR CONDITIONS AT FAY THEN AT RWI/RDU WED AS A WARM FRONT MOVES NORTHWEST THROUGH THE AREA WITH STRENGTHENING SW WINDS... BUT SUB- VFR CONDITIONS MAY HOLD IN LONGER AT INT/GSO. THIS WARM FRONT WILL DROP BACK DOWN SOUTHEAST THROUGH THE AREA AS A COLD FRONT LATE WED OR WED NIGHT... TURNING SURFACE WINDS BACK AROUND TO NORTH/NORTHEASTERLY FOR THU WITH WIDESPREAD RAIN AND SUB-VFR CONDITIONS. VFR CONDITIONS SHOULD RETURN TO NORTHERN SECTIONS (RDU/RWI/INT/GSO) BY THURSDAY NIGHT/FRIDAY. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS EVENING FOR NCZ007-021>023-038-039. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...WSS LONG TERM...BSD AVIATION...HARTFIELD

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