Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 050808 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 405 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 /TUESDAY THROUGH SATURDAY/... AS OF 405 AM SUNDAY... WITH THE DEPARTURE OF THE INCREASINGLY SHEARED UPPER LOW OVER THE SOUTH-CENTRAL APPALACHIANS ON TUESDAY...THE PATTERN OVER THE SOUTHEAST US WILL SHIFT BACK INTO A ORE TYPICAL SUMMERTIME REGIME...WITH THE SUBTROPICAL RIDGE BUILDING ACROSS THE SOUTHERN US. MEANWHILE...PROGRESSIVE FLOW ACROSS THE NORTHERN US WILL ALLOW A SERIES OF SHORTWAVES TO CROSS THE GREAT LAKES REGION... AND TO SOME DEGREE KEEP HEIGHTS ALOFT FROM RISING TOO QUICKLY OVER THE CAROLINAS. THE FIRST SHORTWAVE WILL CROSS THE GREAT LAKES ON WEDNESDAY...WITH A TRAILING COLD FRONT SINKING SOUTH INTO THE MID- ATLANTIC REGION...BUT GIVEN THE FACT THAT MODELS HAVE TRENDED A LITTLE STRONGER...AND WARMER...WITH THE SUBTROPICAL RIDGE....EXPECT THE FRONT TO REMAIN NORTH OF OUR AREA. A LEE TROUGH WILL BE THE MAIN FOCUS FOR ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS EACH DAY...WITH THE POTENTIAL FOR DISTURBANCES TRACKING WEST TO EAST NEAR THE FRONTAL ZONE TO PROVIDE SOME ADDITIONAL FORCING AS THE FRONT EFFECTIVELY TRIED TO SINK SOUTH INTO THE AREA BY THE WEEKEND. THIS WILL BE DEPENDENT ON HOW THE RIDGE EVOLVES...AND THE MODELS ARENT IN FULL AGREEMENT ON HOW QUICKLY THE CENTER OF THE RIDGE WILL BUILD WEST OVER THE SOUTHERN PLAINS...WHICH WOULD ALLOW HEIGHTS TO FALL AGAIN ALONG THE EAST COAST. FOR NOW...WILL CONTINUE TO SHOW MAINLY SLIGHT CHANCE OF LOW END CHANCE POPS EACH DAY...WITH HIGHS INCREASINGLY IN THE 90-95 RANGE. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... 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. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...KRD SHORT TERM...WSS LONG TERM...22 AVIATION..26

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.