Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 041840 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 240 PM EDT SAT JUL 4 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 1040 AM SATURDAY... LITTLE ADJUSTMENT REQUIRED TO THE NEAR TERM FORECAST. 12Z UPPER AIR ANALYSIS DEPICTS DECENT SPEED CONVERGENCE AT 850-700MB ACROSS GA-SC WITH WEAKER CONVERGENCE ACROSS CENTRAL NC. WEAK 850- 700MB TROUGH NOTED ACROSS THE NW PIEDMONT WITH A MORE PRONOUNCED TROUGH DRAPED ACROSS THE OH VALLEY INTO THE MID MS VALLEY. SURFACE BASED INSTABILITY NOMINAL AT 14Z BUT ADDITIONAL HEATING SHOULD CAUSE THE ATMOSPHERE TO BECOME SLIGHT-MODERATELY UNSTABLE BY EARLY AFTERNOON. A WEAK MID LEVEL VORTICITY NOTED BY THE NEAR TERM MODELS SOMEWHAT DISCERNIBLE ON WATER VAPOR IMAGERY AT 14Z ABOUT TO EXIT NE GA INTO UPSTATE SC. THIS FEATURE COUPLED WITH THE DESTABILIZING ATMOSPHERE AND THE CONFLUENCE ZONE OVER SC SHOULD INITIATE AND SUSTAIN SCATTERED CONVECTION OVER OUR SOUTHERN COUNTIES THIS AFTERNOON. DEEP W-SW FLOW THROUGH THE COLUMN WITH 850-700MB WINDS ON THE ORDER OF 30-40KTS. THIS SUGGEST THE POTENTIAL FOR ORGANIZED STORMS IN THE FORM OF BROKEN N-S ORIENTATED BANDS. IF ENOUGH HEATING OCCURS...REALIZING LOW LEVEL LAPSE RATES OF 8-9 DEG C/KM...COULD SEE THE STRONGER STORMS PRODUCE LOCALIZED WIND GUSTS 40- 50KTS. ACROSS THE NORTH...EXPECT SCATTERED CONVECTION TO DEVELOP IN VICINITY OF THE WEAK LOW LEVEL TROUGH BY MID AFTERNOON. WHILE LIKELY NOT AS ROBUST AS THE STORMS TO THE SOUTH...STILL COULD SEE STRING GUSTY WINDS (35-40KTS) WITH THESE STORMS. HAVE NUDGED MAX TEMPS UP A DEGREE OR TWO DUE TO MOSTLY-PARTLY SUNNY SKIES WHICH MAY PERSIST UNTIL EARLY AFTERNOON. AFTERWHICH...CLOUDS THICKEN IN RESPONSE TO HEATING/CONVECTIVE DEVELOPMENT. AREA SOUNDINGS DEPICT LOW LEVEL WINDS JUST ABOVE THE SURFACE CLOSE TO 25- 30KTS. ONCE LOW LEVEL INVERSION LIFTS (ONCE TEMPS EXCEED 80-LOWER 80S)...SHOULD SEE BREEZY W-SW WINDS WITH FREQUENT GUSTS AROUND 25 MPH...ESPECIALLY ACROSS THE SOUTHERN COUNTIES. EXPECT SCATTERED CONVECTION TO DIMINISH EARLY THIS EVENING AS UPPER LEVEL SUPPORT WANES AND LOW LEVEL CONVERGENCE WEAKENS. BULK OF SCATTERED CONVECTION SHOULD DIMINISH BY 9-10 PM. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 430 AM SATURDAY... A SHORTWAVE TROUGH OVER THE CENTRAL PLAINS THIS MORNING WILL AMPLIFY INTO THE BASE OF THE L/W TROUGH AND CAUSE A MID LEVEL LOW TO BRIEFLY CLOSE OFF AND LIFT THROUGH THE SOUTHERN AND CENTRAL APPALACHIANS SUN- SUN NIGHT...WHILE A GENERALLY EAST-WEST ORIENTED LOW LEVEL FRONTAL ZONE WILL LINGER NEAR OR JUST SOUTH OF THE VA/NC BORDER. STORMS INITIALLY WILL LIKELY FIRE OVER OR JUST OUTSIDE OF THE RAH CWFA BORDERS...TO THE WEST IN ASSOCIATION WITH THE INFLUENCE OF THE CLOSED LOW; ALONG THE NORTHERN PIEDMONT INVOF THE SURFACE FRONT; AND TO THE EAST ALONG THE SEA BREEZE. EACH WILL SEND OUTFLOW AND ASSOCIATED MULTI-CELL STORM DEVELOPMENT DIRECTED THROUGHOUT THE REMAINDER OF CENTRAL NC. HIGH PWAT (>1.75") AND LIMITED CINH/LOW LFC HEIGHTS WILL FAVOR NUMEROUS COVERAGE...WITH A PRIMARY THREAT OF LOCALIZED FLOODING OWING TO BOTH SLOW MOVEMENT AND PROBABLE PERPETUAL REDEVELOPMENT ATOP THE CONVECTIVE OUTFLOW-MODULATED FRONTAL ZONE. HIGHS IN THE 80S...WARMEST NEAR 90 DEGREES OVER THE SANDHILLS...WITH LOWS MOSTLY IN THE LOWER 70S. && .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 /18Z SATURDAY THROUGH THURSDAY/... AS OF 215 PM SATURDAY... SCATTERED CONVECTION AND ASSOCIATED MVFR CONDITIONS WILL OCCUR ACROSS CENTRAL NC THROUGH 00Z. EXPECT WIND GUSTS 30-40KTS IN VICINITY OF THE STORMS. THE BULK OF THE CONVECTION WILL DIMINISH BETWEEN 00Z-03Z THOUGH A STRAY SHOWER OR TWO MAY OCCUR WELL INTO THE NIGHT...MAINLY OVER THE NW PIEDMONT. ASIDE FROM THE CONVECTION...EXPECT VFR CONDITIONS. THE WEATHER PATTERN ACROSS CENTRAL NC WILL REMAIN UNSETTLED THROUGH TUESDAY AS A SERIES OF DISTURBANCES ALOFT INTERACT WITH THE AVAILABLE MOISTURE AND INSTABILITY TO TRIGGER SCATTERED CONVECTION AND ASSOCIATED MVFR CONDITIONS. IN ADDITION...THERE MAY BE A RISK OF EARLY MORNING MVFR/IFR CONDITIONS DUE TO FOG AND OR LOW CLOUDS. AFTERNOON CONVECTION IS EXPECTED TO BECOME LESS LIKELY BY MID WEEK AS AN UPPER LEVEL RIDGE SLOWLY BUILDS INTO THE REGION. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...WSS SHORT TERM...26 LONG TERM...BSD AVIATION..WSS

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