Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 050630 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 230 AM EDT SUN JUL 5 2015 .SYNOPSIS... A SERIES OF DISTURBANCES ALOFT WILL MOVE OVERHEAD AND INTERACT WITH A SURFACE FRONT THAT WILL WAVER ACROSS VA AND NC THROUGH MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 PM SATURDAY... CONVECTION HAS BEEN ISOLATED TO WIDELY SCATTERED THIS EVENING. MODEST INSTABILITY (500-1000 J/KG) IS STILL DEPICTED ON THE SPC MESOSCALE ANALYSIS BUT CIN IS ON THE INCREASE. CONVECTION ACROSS THE NORTHERN TIER OF THE FORECAST AREA MAY PERSIST A BIT LONGER AS AN UPPER LEVEL SHEAR AXIS HELPS TO FOCUS THE PRECIP. IN ADDITION...A SURFACE BOUNDARY IS ALSO LOCATED IN THIS VICINITY. THE SHEAR AXIS IS PROGGED TO LIFT NORTHWARD THROUGH 06Z...HOWEVER ANOTHER VORT MAX IS EXPECTED TO TRACK EAST-NORTHEASTWARD FROM SW TN THROUGH 12Z. HOWEVER...AT THIS TIME IT APPEARS IT WILL REMAIN FAR ENOUGH WEST TO HAVE TOO MUCH INFLUENCE ON OUR AREA (EXCEPT POSSIBLY OVER THE FAR NORTHWEST PIEDMONT). NEVERTHELESS...GIVEN THE MOISTURE RICH AIR MASS...A FEW SHOWERS MAY PERSIST THROUGH THE OVERNIGHT HOURS. OVERNIGHT LOWS WILL BE SIMILAR TO PREVIOUS NIGHTS...GENERALLY UPPER 60S TO LOWER 70S. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 310 PM SATURDAY... MID-UPPER LEVEL TROUGH OVER THE TN VALLEY AMPLIFIES...CAUSING HEIGHTS OVER OUR REGION TO SLOWLY BUILD/EXPAND NORTHWARD. THIS WEAK SUBSIDENCE MAY INITIALLY INHIBIT CONVECTIVE DEVELOPMENT...ESPECIALLY ACROSS OUR SE COUNTIES. PERTURBATIONS ALOFT CROSSING WESTERN NC INTO WESTERN VA WILL AID TO FOCUS LOW LEVEL CONVERGENCE OVER THE NW PIEDMONT...LEADING TO SCATTERED CONVECTION BY AFTERNOON-EARLY EVENING. SINCE MAJORITY OF MODEL GUIDANCE HAS BACKED OFF ON UPPER SUPPORT...HAVE LIMITED POPS TO SOLID CHANCE ACROSS THE NW...TRENDING TO SMALL CHANCE ACROSS THE SE. MAX TEMPS SUNDAY AFTERNOON WILL FOLLOW SIMILAR TREND WITH MID 80S NW DUE TO MIXTURE OF SUN/CLOUDS TO AROUND 90 SE. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 240 PM SUNDAY... A WEAKENING MID LEVEL LOW INVOF THE SOUTHERN TO CENTRAL APPALACHIANS MONDAY MORNING IS EXPECTED TO LIFT NORTHWARD AND WEAKEN MONDAY NIGHT INTO TUESDAY. THE TRAILING ASSOCIATED WEAK S/W TROUGH IS EXPECTED TO MOVE ACROSS CENTRAL NC ON MONDAY INTO MONDAY NIGHT. THUS... EXPECT WE COULD SEE SOME SCATTERED SHOWERS AND STORMS MONDAY AFTERNOON INTO THE EVENING AGAIN... WITH THE HIGHEST PROBABILITY ACROSS THE NORTH AND EASTERN PORTIONS OF CENTRAL NC. THE SUB-TROPICAL RIDGE IS THEN FORECAST TO ATTEMPT TO BUILD BACK OVER THE SOUTHEASTERN U.S. HOWEVER... AS A SERIES OF NORTHERN STREAM DISTURBANCES TRACK ACROSS THE NORTHERN TIER OF THE COUNTRY THE MID LEVEL RIDGE WILL HAVE A HARD TIME FULLY EXERTING ITS DOMINATES ON CENTRAL NC... WITH ANY ASSOCIATED SURFACE FRONT GENERALLY REMAINING TO THE NORTH OF CENTRAL NC INTO AT LEAST LATE WEEK. HOWEVER... AS ANY SUBSTANTIAL DISTURBANCES AND ASSOCIATED FRONTS PASS TO THE NORTH OF CENTRAL NC... EXPECT WE SHOULD STILL SEE A SHARPENING OF THE PIEDMONT TROUGH OVER CENTRAL NC DURING THIS THE MEDIUM RANGE... HELPING TO YIELD ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS EACH AFTERNOON AND EVENING. HIGH TEMPS DURING THE PERIOD WILL START OFF SLIGHTLY BELOW NORMAL... GENERALLY IN THE MID TO UPPER 80S ON MONDAY... WITH HIGHS REBOUNDING TO AROUND NORMAL FOR THE REST OF THE PERIOD (UPPER 80S TO LOWER 90S. LOW TEMPS ARE EXPECTED TO BE IN THE UPPER 60S TO LOWER 70S... WITH POSSIBLY A FEW MID 70S BY LATE WEEK INTO NEXT WEEKEND. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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AS OF 225 AM SUNDAY... GENERALLY LIGHT SOUTH TO SOUTHWEST LOW LEVEL FLOW WILL PREVAIL OVER CENTRAL NC...ON THE SOUTH SIDE OF A SURFACE FRONTAL ZONE FORECAST TO SETTLE TO NEAR THE VA/NC STATE LINE LATER THIS MORNING. THE FRONT IS THEN FORECAST TO BECOME QUASI-STATIONARY AND FOCUS SCATTERED SHOWERS AND STORMS THIS AFTERNOON...INITIALLY MOST PROBABLE AT TRIAD TAF SITES AND RDU...IN CLOSEST PROXIMITY TO BOTH THE FRONT AND AN UPPER LEVEL TROUGH FORECAST TO DRIFT SLOWLY NORTHEAST ACROSS THE TN VALLEY. THE TROUGH ALOFT...AND PRECEDING WEAK IMPULSES IN SOUTHWESTERLY FLOW ALOFT...WILL PROBABLY TRIGGER A NORTH TO SOUTH- ORIENTED BAND OR TWO OF ADDITIONAL SHOWERS AND STORMS THROUGH THIS EVENING...BUT CONFIDENCE IN LOCATION AND TIMING IS LOW AT THIS TIME. OTHERWISE...THE HI-RES RAPID REFRESH MODEL (HRRR) SUGGESTS POCKETS OF IFR-MVFR STRATUS WILL EXPAND FROM AL/GA NORTHEASTWARD ACROSS SC...AND INTO SOUTHERN NC (INCLUDING FAY) BETWEEN 10-15Z. ALTHOUGH THE CONSENSUS OF OTHER MODEL GUIDANCE MAINTAINS VFR CONDITIONS AT FAY AND ELSEWHERE...THE RECENT GOOD TRACK RECORD OF THE HRRR VERSUS OTHER GUIDANCE WILL BE FOLLOWED; AND A TEMPO GROUP FOR MVFR CEILINGS HAS BEEN INCLUDED AT KFAY FOR A FEW HOURS LATER THIS MORNING. OUTLOOK: THE AFOREMENTIONED UPPER LEVEL TROUGH OVER THE TN VALLEY WILL CONTINUE TO LIFT SLOWLY NORTHEAST THROUGH THE APPALACHIANS AND DIRECT A MOIST AND WEAKLY PERTURBED SOUTHWEST FLOW ALOFT ACROSS NC THROUGH TUE. ABOVE AVERAGE PROBABILITIES OF MAINLY AFTERNOON-EARLY NIGHTTIME SHOWERS AND STORMS --AND ASSOCIATED SUB-VFR CONDITIONS-- WILL RESULT...WITH THE RELATIVE BETTER CHANCES ON MON. SUB-TROPICAL RIDGING WILL THEN EXPAND NORTH THROUGH MID-LATE WEEK...WITH ASSOCIATED MAINLY DRY AND WARMER/HOT CONDITIONS.
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&& ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...KRD SHORT TERM...WSS LONG TERM...BSD AVIATION..26

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