Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 290711 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 311 AM EDT WED OCT 29 2014 .SYNOPSIS... A COLD FRONT WILL CROSS OUR REGION THIS AFTERNOON AND EVENING. HIGH PRESSURE WILL FOLLOW FOR THU THROUGH FRI. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 933 PM TUESDAY... FORECAST PRETTY MUCH ON TRACK. FEW IF ANY ADJUSTMENTS NEEDED. HIGH PRESSURE OFFSHORE AND A LEE-SIDE TROUGH AHEAD OF A STRONG COLD FRONT WILL MAINTAIN A LIGHT THOUGH STEADY SSW FOW OVER CENTRAL NC OVERNIGHT. THIS FLOW WILL ADVECT LOW LEVEL MOISTURE. THIS IS ALREADY EVIDENT AS SFC DEWPOINTS HAVE RECOVERED INTO THE 50S. LATEST SREF GUIDANCE CONSISTENT IN ITS DEPICTION OF A BAND OF LOW STRATUS DEVELOPING AFTER 04Z...MAINLY ACROSS THE COASTAL PLAIN. MEANWHILE UPPER LEVEL MOISTURE WILL BE INCREASING ALOFT AS L/W TROUGH MOVES STEADILY THOUGH SLOWLY EAST TOWARD THE CAROLINAS OVERNIGHT. THE INCREASINGLY MOIST AIR MASS WILL YIELD OVERNIGHT TEMPS 6-9 DEGREES WARMER THAN LAST NIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 AM THURSDAY/... AS OF 240 PM TUESDAY... MODELS IN GOOD AGREEMENT WITH THE TIMING OF THE COLD FRONT AND ASSOCIATED NARROW BAND OF LOW-TOP CONVECTION THROUGH THE AREA WEDNESDAY AFTERNOON-EVENING...~18Z IN THE TRIAD...-21Z THROUGH THE TRIANGLE...EXITING COASTAL PLAIN/I-95 CORRIDOR ~00Z THU. WHILE FAVORABLE DIURNAL TIMING WILL ALLOW FOR SOME DECENT HEATING FROM THE TRIANGLE EASTWARD...WEAK LOW-LEVEL LAPSE RATES AND RELATIVELY LOW SFC DEWPOINTS IN THE MID TO UPPER 50S WILL LIMIT INSTABILITY AND WILL PRECLUDE ANY SEVERE THREAT...THOUGH A CLAP OR TWO OF THUNDER WILL BE POSSIBLE. COMMENCEMENT OF STRONG CAA ACROSS THE WESTERN PIEDMONT DURING THE LATTER/SECOND HALF OF THE DAY...COINCIDENT WITH TYPICAL PEAK HEATING...WILL MAKE FOR A LARGER THAN NORMAL NW-SE TEMPERATURE GRADIENT ACROSS THE FORECAST AREA. HIGHS RANGING FROM MID/UPPER 60S NW TO UPPER 70S SE. POST-FRONTAL HIGH PRESSURE AND CAA WILL LEAD TO WEST-EAST CLEARING OVERNIGHT. LOWS 45 TO 55. && .LONG TERM /FRIDAY THROUGH TUESDAY/...
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AS OF 310 AM WEDNESDAY... WEAK HIGH PRESSURE WILL BE OVER THE AREA EARLY ON FRIDAY... AHEAD OF STRONG SHORTWAVE DIVING IN TO THE BASE OF A TROUGH OVER THE EASTERN US. RECENT MODEL TRENDS HAVE SHOWN THIS SHORTWAVE MOVING MUCH FURTHER SOUTHWARD THAN PREVIOUS RUNS... AND INCREASINGLY AMPLIFIED MIDLEVEL FLOW... WITH A CLOSED UPPER LOW CROSSING THE AREA AND INDUCING COASTAL SURFACE LOW DEVELOPMENT. THE RESULTING STRONG PRESSURE GRADIENT WILL BRING BLUSTERY WINDS SATURDAY. IF THIS SCENARIO PLAYS OUT... WE WILL SEE A COLD AND WET DAY... WITH HIGHS IN THE 40S. HAVE BEGUN TO TREND HIGHS LOWER... AND INCREASED TO CHANCE POPS SATURDAY. AS NOTED BY WPC... THE FORECASTED PATTERN IS QUITE ANOMALOUS... AND THEREFORE CONFIDENCE REMAINS BELOW NORMAL AT THIS TIME. SUBSIDENCE IN THE WAKE OF THE DEPARTING LOW WILL BRING CLEARING CONDITIONS ON SUNDAY... WHICH WILL WORK TO PARTIALLY OFFSET COLD ADVECTION... WITH HIGHS REACHING THE 50S. STRONG AND COLD HIGH PRESSURE BUILDING IN TO THE OHIO VALLEY ON SUNDAY WILL MOVE DIRECTLY OVER THE AREA ON MONDAY... WITH FROST AND POSSIBLY FREEZE POTENTIAL SUNDAY AND MONDAY MORNINGS. THE HIGH MOVES OFF THE EAST COAST ON TUESDAY... BEGINNING A MODERATING TREND IN TEMPERATURES... WITH HIGHS BACK IN THE 60S MONDAY AND TUESDAY.
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&& .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 220 AM WEDNESDAY... ASIDE FROM A MEDIUM PROBABILITY OF LIFR-IFR STRATUS AT KFAY BETWEEN 10-14Z...VFR CONDITIONS ARE EXPECTED UNTIL A COLD FRONT AND ASSOCIATED BAND OF ALONG AND POST-FRONTAL SHOWERS - AND ASSOCIATED IFR-MVFR CEILINGS AND MVFR VISIBILITY RESTRICTIONS - MOVES EAST ACROSS CENTRAL NC THIS AFTERNOON AND EVENING. THE SHOWERS AND SUB-VFR CONDITIONS ARE EXPECTED TO LAST ONLY AROUND 3 HOURS AT ANY ONE LOCATION. A PERIOD OF VFR CEILINGS BETWEEN 4-8 THOUSAND FT WILL LINGER FOR A FEW HOURS EVEN AFTER THE SHOWERS AND SUB-VFR CONDITIONS MOVE EAST. OTHERWISE...SW SURFACE WINDS BETWEEN 7-13 KTS...STRONGEST AND OCCASIONALLY GUSTY INTO THE UPPER TEENS KTS AT FAY AND RWI...WILL VEER TO WNW OR NW BEHIND THE FRONT. OUTLOOK: THE PASSAGE OF A STRONG POLAR FRONT AND SUBSEQUENT DEVELOPMENT OF A STRONG COASTAL LOW WILL RESULT IN A CHANCE OF RAIN...AND BLUSTERY NW WINDS...FRI NIGHT THROUGH SAT. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...WSS SHORT TERM...CBL LONG TERM...SEC AVIATION...MWS

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