Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 130501 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 101 AM EDT SUN APR 13 2014 .SYNOPSIS...
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WARM AND DRY HIGH PRESSURE CENTERED OVER THE WESTERN ATLANTIC WILL EXTEND WESTWARD OVER OUR REGION TODAY. A COLD FRONT WILL SLOWLY APPROACH THE REGION FROM THE WEST ON MONDAY...THEN MOVE EAST ACROSS NORTH CAROLINA AND VIRGINIA MONDAY NIGHT AND TUESDAY.
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&& .NEAR TERM /THROUGH SUNDAY NIGHT/... AS OF 955 PM SATURDAY... SURFACE TO MID-LEVEL RIDGE CONTINUES OVER THE CAROLINAS THIS EVENING...WITH JUST A PATCH OF THINNING CIRRUS APPROACHING FROM THE WEST. A LIGHT SOUTHERLY WIND WILL PERSIST AT MANY LOCATIONS...AND WHILE FORECAST SOUNDINGS SHOW MOISTENING IN THE LOWEST 5000 FT OVERNIGHT...IT SHOULD BE ENOUGH FOR STRATUS TONIGHT. MILD LOWS IN THE MID AND UPPER 50S. -SMITH WITH SHORTWAVE RIDGING OVERHEAD AND OFFSHORE SURFACE HIGH PRESSURE STILL EXTENDING INTO THE REGION...EXPECTING CONTINUED QUIET WEATHER FOR CENTRAL NC. SOUTHERLY FLOW WILL DEVELOP AREAWIDE AS A BOUNDARY THAT WAS DRAPED ACROSS THE AREA THIS MORNING WASHES OUT. THIS WILL CAUSE LOW LEVEL MOISTURE TO BEGIN TO SLOWLY INCREASE THROUGH THE OVERNIGHT HOURS. AS A RESULT...OVERNIGHT LOWS WILL LIKELY BE A COUPLE OF DEGREES WARMER...GENERALLY IN THE MID TO UPPER 50S. BOTH THE UPPER LEVEL AND SURFACE RIDGING WILL PUSH FURTHER OFFSHORE ON SUNDAY AHEAD OF AN APPROACHING DEEP TROUGH/STRONG COLD FRONT. STRENGTHENING SOUTHWESTERLY FLOW WILL BEGIN TO ADVECT MOISTURE EVEN MORE SO INTO CENTRAL NC. DESPITE THIS INCREASING MOISTURE...IN THE ABSENCE OF ANY SIGNIFICANT FORCING AND A FAIRLY CAPPED AIR MASS (PER FORECAST SOUNDINGS)...SUNDAY IS EXPECTED TO REMAIN DRY. MAX LOW LEVEL THICKNESS VALUES ARE PROGGED TO BE SIMILAR THOSE SEEN ON SATURDAY AND THEREFORE...HIGHS SHOULD ONCE AGAIN BE IN THE UPPER 70S TO LOWER 80S. CLOUDS WILL BE ON THE INCREASE... ESPECIALLY LATE SUNDAY INTO EARLY MONDAY. THEREFORE OVERNIGHT LOWS WILL BE EVEN WARMER...WITH TEMPS ONLY EXPECTED TO FALL INTO THE UPPER 50S TO AROUND 60 DEGREES. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 244 PM SATURDAY... DEEP TROUGH OVER THE CENTRAL US WILL PUSH EASTWARD. AN INITIAL SHORTWAVE WILL EJECT NORTHEASTWARD... WITH SECOND TRAILING SHORTWAVE DIGGING INTO THE SOUTHERN PLAINS. MOISTURE WILL BEGIN TO INCREASE AHEAD OF THIS SYSTEM ACROSS THE AREA... AND MODEL TRAJECTORIES SHOW GULF MOISTURE BEGINNING TO STREAM IN TO THE AREA MONDAY AFTERNOON... AND SHALLOW ISENTROPIC LIFT MAY INDUCE SOME SHOWER ACTIVITY... WITH THE POSSIBILITY OF A THUNDERSTORM. CONTINUED MILD HIGHS IN THE MID TO UPPER 70S. TIMING OF THE FRONTAL PASSAGE LOOKS TO BE BETWEEN 18Z TUES AND 06Z WED... DIFFICULT TO PINPOIN BASED ON THE POTENTIAL WAVY NATURE OF THE FRONT. INSTABILITY LOOKS LIKELY TO REMAIN LIMITED... WITH CLOUD COVER ACROSS THE AREA... ALTHOUGH BASED ON THE LATER DAY TIMING SOME WEAKER INSTABILITY IS POSSIBLE... AND IN CONCERT WITH MARGINAL SHEAR... A 120 KT JET SITUATED ALONG THE APPALACHIANS... AND FRONTOGENETICAL FORCING... MAY SUPPORT A FEW STRONGER STORMS. HEAVY RAIN IS ALSO A THREAT... WITH PWS CLIMBING ABOVE 1.5 INCHES... 2 STD DEV ABOVE CLIMATOLOGY. COOLER HIGHS IN THE UPPER 60S TO LOW 70S. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 245 PM SATURDAY... ECMWF REMAINS SLOWER AND SHARPER WITH THE PROGRESSION OF THE SHORTWAVE ACROSS THE AREA... AND THE POTENTIAL EXISTS FOR SECONDARY SURFACE WAVE DEVELOPMENT... WHICH COULD RESULT IN LINGERING PRECIPITATION CHANCES INTO WEDNESDAY. AS THE SYSTEM DEPARTS... A 1035 MB HIGH BUILDS IN TO THE NORTHEAST AND WEDGES DOWN THE EAST COAST... BRINGING NORTHEASTERLY FLOW TO THE AREA. COLDEST NIGHT LOOKS TO BE WEDNESDAY NIGHT ... WITH FROST/FREEZE CONCERNS LOOKING INCREASINGLY LIKELY ACROSS MUCH OF THE AREA. THE WEDGE MAY STAY IN PLACE THROUGH THE REMAINDER OF THE PERIOD... AS THE DETAILS OF THE EROSION MECHANISM IN THE FORM OF A NORTHERN STREAM ARE QUITE UNCERTAIN AT THIS TIME PERIOD. WEDGE REGIME WILL RESULT IN BELOW NORMAL TEMPERATURES... POTENTIALLY LASTING INTO SATURDAY. && .AVIATION /06Z SUNDAY THROUGH FRIDAY/...
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AS OF 1 AM SUNDAY... VFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE 24 HOUR TAF PERIOD. HOWEVER... LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE IN STRENGTHENING SOUTHERLY RETURN FLOW AROUND HIGH PRESSURE OFFSHORE. THIS COULD POSSIBLY EVEN LEAD TO SOME PATCHY LOW STATUS ACROSS WESTERN PORTIONS OF CENTRAL NC. AT THIS TIME WILL NOT MENTION ANY SUB-VFR CONDITIONS EARLY THIS MORNING... AS ANY PATCHY STRATUS WOULD BE RIGHT AROUND SUNRISE AND BE VERY LIMITED IN COVERAGE... IF ANY DEVELOPS AT ALL. OTHERWISE... EXPECT SOME FLAT CUMULUS WILL DEVELOP TODAY GENERALLY IN THE 4 TO 6 KFT RANGE WITH SUSTAINED WINDS INCREASE BY LATE MORNING INTO THE AFTERNOON IN THE 10 TO 13 KT RANGE... WITH GUSTS IN THE LATE MORNING TO AFTERNOON TIME FRAME OF UP TO 20 KTS POSSIBLE. OUTLOOK... LOW STRATUS/FOG MAY DEVELOP EARLY MONDAY MORNING AS LOW LEVEL MOISTURE INCREASES FURTHER. THEN A PERIOD OF WIDESPREAD ADVERSE AVIATION CONDITIONS IS EXPECTED LATE MONDAY THROUGH TUESDAY AS A STRONG COLD FRONT APPROACHES FROM THE WEST. CONDITIONS SHOULD IMPROVE TO VFR FOR WED INTO FRI AS A COOL HIGH PRESSURE RIDGE EXTENDS INTO CENTRAL NC FROM THE NORTH.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BSD/HARTFIELD NEAR TERM...KRD/SMITH SHORT TERM...SEC LONG TERM...SEC AVIATION...BSD/HARTFIELD

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