Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 241729 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1224 PM EST SAT JAN 24 2015 .SYNOPSIS... A STRONG STORM SYSTEM WILL LIFT UP ALONG THE NEW ENGLAND COAST THIS AFTERNOON AS THE UPPER LEVEL TROUGH MOVES EAST ACROSS NORTH CAROLINA. HIGH PRESSURE WILL BUILD OVER THE REGION TONIGHT THROUGH SUNDAY. && .NEAR TERM /THROUGH TODAY/... AS OF 1101 AM SATURDAY... ONE FINAL... BUT STRONG... VORTICITY MAXIMUM ALOFT SEEN ON SATELLITE IMAGERY ROUNDING THE BASE OF THE RAPIDLY APPROACHING DEEP TROUGH... WILL PUSH ACROSS THE REGION DURING THE EARLY TO MID AFTERNOON. A LARGE AREA OF LIGHT RAIN HAS FILLED BACK IN ACROSS ALL OF THE FOOTHILLS AND PIEDMONT AS OF LATE MORNING. EVEN A FEW CONVECTIVE ELEMENTS WERE NOTED ON RADAR ASSOCIATED WITH THE STRONG VORTICITY ALOFT NEAR CHARLOTTE AT LATE MORNING. ALL THIS WAS OCCURRING AS THE BOMBING SURFACE LOW PRESSURE HAD ALREADY PULLED WELL OFF THE COAST OF DELMARVA (SUPPLYING PARTS OF NEW ENGLAND WITH HEAVY SNOW). ONCE THE MID/UPPER TROUGH AND THE VORT MAX PASS... THE RAIN WILL END QUICKLY. STRONG SUBSIDENCE ON THE BACK SIDE OF THE TROUGH AS WELL AS NVA IN THE REAR OF THE DEPARTING VORT MAX WILL COMBINE WITH DEVELOPING DOWNSLOPE FLOW OFF THE BLUE RIDGE IN THE NEXT HOUR OR SO... TO PRODUCE A SHARP BACK EDGE TO THE CURRENT RAIN EVENT. THIS BACK EDGE OF THE RAIN (END) WILL PUSH ENE ACROSS OUR REGION BETWEEN NOON AND 300 PM. THEREFORE... WE WILL EXTEND CATEGORICAL POP THROUGH THAT TIME IN OUR UPDATED FORECAST. QPF WILL BE LIGHT (0.01 TO 0.10) AND OBVIOUSLY ALL RAIN AS TEMPERATURES WERE IN THE UPPER 30S AND 40S. PARTIAL SUNSHINE WILL RETURN THIS AFTERNOON FROM WEST TO EAST... BUT THE NE MAY NOT SEE CLEARING UNTIL NEAR SUNSET. BREEZY WESTERLY WINDS AT 10-20 MPH WILL ADD A BIT OF A CHILL TO THE FORECAST HIGHS IN THE MID 40S TO MID 50S. POP TO NIL LATER TODAY - AND SKIES TO MOSTLY CLEAR AS WELL. -BADGETT && .SHORT TERM /TONIGHT THROUGH MONDAY/... AS OF 210 AM SATURDAY... FOR TONIGHT INTO SUNDAY EXPECT MOSTLY CLEAR SKIES WITH LIGHT WINDS OUT OF THE WEST SOUTHWEST AND MINIMUM TEMPERATURES RIGHT AROUND THE FREEZING MARK. SUN: EXPECT PLENTY OF SUNSHINE FOR MOST OF SUNDAY... AS THE SURFACE RIDGE EXTENDS WEAKLY AND BRIEFLY INTO NC FROM THE SW WITH DRY AIR IN PLACE THROUGH THE COLUMN. HIGH CLOUDS WILL INCREASE AND THICKEN FROM MID AFTERNOON ONWARD AHEAD OF THE STRONG CLIPPER LOW TRACKING FROM THE UPPER MIDWEST INTO THE OH VALLEY. THICKNESSES ARE EXPECTED TO START THE DAY CLOSE TO NORMAL AND RISE DECENTLY THROUGH THE DAY... EQUATING TO HIGHS A COUPLE DEGREES ABOVE NORMAL... SUN NIGHT/MON/MON NIGHT: THE POTENT CLIPPER SURFACE LOW WILL MOVE FROM AROUND CINCINNATI EARLY SUN EVENING (THE 00Z GFS IS A TAD SLOWER THAN THE NAM WHILE THE ECMWF IS THE FASTEST BY NEARLY 6 HRS) ACROSS SW VA AND NORTH-CENTRAL/NE NC THROUGH MON MORNING. THE GFS HAS BEEN TRENDING DEEPER AND A TAD FASTER WHILE THE ECWMF HAS EXHIBITED MORE RUN-TO-RUN CONSISTENCY... SO FAVOR A GFS/ECMWF COMPROMISE WITH A LEAN TOWARD THE FASTER ECMWF. THE MID LEVEL SHORTWAVE TROUGH PIVOTS OVER NC EARLY MON MORNING BUT SHEARED VORTICITY DIVING IN JUST BEHIND THE TROUGH WILL KEEP A THREAT OF FORCING FOR ASCENT OVER NC FROM MID-LATE SUN EVENING (SLIGHTLY SLOWER ONSET GIVEN THE INITIALLY HIGH CLOUD BASES AND DRY SUBCLOUD LAYER) WELL INTO MON... WITH LINGERING LIGHT PRECIP CHANCES PARTICULARLY OVER THE NRN AND ERN CWA INTO LATE AFTERNOON OR EARLY MON EVENING. THERE ISN`T A GREAT DEAL OF MOISTURE RETURN WITH THIS SYSTEM... WITH PW EXPECTED TO REACH JUST SLIGHTLY ABOVE NORMAL... AND DESPITE IT BEING A PRETTY ROBUST TROUGH AND SURFACE LOW... THE OVERALL LIFT IS NOT TERRIBLY STRONG AS THE GREATEST UPPER DIVERGENCE WILL BE FOCUSED TO OUR SE. THESE TWO FACTORS SHOULD NOT ONLY RESULT IN FAIRLY LIGHT QPF BUT MAY ALSO HELP DETERMINE PTYPE. FORECAST THICKNESSES INDICATE A PTYPE TRENDING FROM LIGHT RAIN TOWARD INDETERMINANT (LIKELY MEANING LITTLE TO NO PRECIP EXPECTED) BEFORE TRENDING TOWARD A SNOW SOUNDING LATE MON. BUT THE MARGINAL LIFT AND MOISTURE ABOVE THE -12C LEVEL SUGGESTS THAT THIS IS LIKELY TO BE A PRIMARILY LIGHT-RAIN EVENT... ALTHOUGH THIS COULD EASILY BE MIXED WITH OR CHANGE TO WET FLAKES IF POCKETS OF SUFFICIENT LIFT CAN BE ACHIEVED TO SATURATE THE ICE NUCLEATION ZONE ALOFT. THIS OCCURRENCE IS FAR FROM CERTAIN HOWEVER (ALTHOUGH THE CHANCES APPEAR BETTER NEAR THE VA/NC BORDER)... SO WILL CONTINUE TO FOCUS ON A MOSTLY RAIN EVENT WITH A SMALLER CHANCE OF INCONSEQUENTIAL WET SNOWFLAKES AS THE TROUGH SHIFTS TO OUR EAST MON AFTERNOON INTO THE EVENING. WE MAY ACTUALLY SEE A LULL IN ANY PRECIP MON AFTERNOON THEN RENEWED LIFT MON EVENING AS THE STRONG NRN STREAM JET ACCELERATES TO THE SE WITH A RESULTING UPTICK OF UPPER DIVERGENCE OVER NC. WILL BRING IN CHANCE POPS ACROSS THE NORTH AND NE STARTING LATE SUN EVENING... WITH SMALLER CHANCES SOUTH... CONTINUING THROUGH MON BEFORE TAPERING DOWN MON NIGHT. EXPECT OVERALL AMOUNTS TO BE A TENTH OF AN INCH OR LESS... AS INDICATED BY OPERATIONAL MODELS AND SREF MEMBERS. RAIN CHANCES AND CLOUDS WILL HOLD TEMPS DOWN MON... AND THICKNESSES AND GUIDANCE SUPPORT HIGHS FROM THE MID 40S NORTH TO LOWER 50S SOUTH... AFTER MORNING LOWS IN THE MID-UPPER 30S. AS THE SURFACE LOW INTENSIFIES MON NIGHT EAST OF NJ/SE OF CAPE COD... COLD AIR ADVECTION WILL COMMENCE INTO NC... AND EXPECT LOWS IN THE UPPER 20S TO AROUND 30. -GIH && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 220 AM SATURDAY... TUE: ADDITIONAL WEAK SHEARED VORTICITY WILL DIVE SE THROUGH THE CAROLINAS TUE WITH THE GFS/ECMWF INDICATING A WEAK ATTENDING SURFACE LOW. THE GFS AND ITS FURTHER-NORTH VORTICITY TRACK GENERATES PATCHY LIGHT PRECIP OVER CENTRAL NC TUE... BUT IT`S UNCLEAR IF WE`LL GET ENOUGH RECOVERY OF LOW LEVEL MOISTURE FOR ANYTHING MEASURABLE AT THE SURFACE. WILL KEEP THE FORECAST DRY FOR NOW WITH THE CHANCE FOR MEASURABLE PRECIP UNDER 15%. WE SHOULD SEE PLENTY OF CLOUDS HOWEVER... AND THICKNESSES WITH STRONG LOW LEVEL COLD AIR ADVECTION INDICATE HIGHS IN THE UPPER 30S TO MID 40S. WED-FRI: SHOULD BE FAIRLY QUIET. THE LONGWAVE TROUGH AXIS FINALLY SHIFTS EAST OFF THE COAST WED... FOLLOWED BY EITHER FLAT WNW FLOW OR WEAK SHORTWAVE RIDGING. SURFACE HIGH PRESSURE WILL SHIFT OVERHEAD THEN TO OUR EAST... SO EXPECT A MODIFICATION OF TEMPS BY LATE WEEK AS WE GET INTO SOUTHWESTERLY RETURN FLOW. ANOTHER NORTHERN STREAM CLIPPER WAVE SHIFTS BY TO OUR NORTH THU NIGHT/FRI... ACROSS IL/IN/OH AND THE CENTRAL APPALACHIANS TO THE MIDATLANTIC COAST... WITH A CORRESPONDING FRONTAL PASSAGE THROUGH CENTRAL NC FRI... POTENTIALLY KNOCKING TEMPS BACK DOWN BELOW NORMAL AS WE HEAD INTO THE WEEKEND. -GIH && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 1215 PM SATURDAY... RAPID IMPROVMENTS TO VFR CONDITIONS ARE EXPECTED BETWEEN 18Z AND 21Z ACROSS OUR REGION. THE MID/UPPER TROUGH AXIS WILL PASS OVERHEAD DURING THIS TIME. ONCE THE TROUGH PASSES... RAPID CLEARING WILL ENSUE. THIS PROCESS HAD ALREADY BEGUN AT KHKY... KCLT AND KGSP BY 17Z. WINDS WILL BE GUSTY FROM THE WEST THIS AFTERNOON AT 10-20KT. OTHERWISE... VFR CONDITIONS WILL BE FOUND TONIGHT AND SUNDAY WITH LIGHT WINDS. LONG TERM: GENERALLY VFR CONDITIONS FORECAST FOR THE LONG TERM SUNDAY NIGHT INTO THURSDAY. THE EXCEPTION TO THIS COULD BE WITH A CLIPPER SYSTEM ON MONDAY THROUGH MONDAY NIGHT WHICH COULD PRESENT A FEW PERIODS OF MVFR CIGS AND POSSIBLY A LIGHT SHOWER OR TWO ACROSS MAINLY NORTHERN NC. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT SHORT TERM...ELLIS/HARTFIELD LONG TERM...HARTFIELD AVIATION...BADGETT

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