Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 031752 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 155 PM EDT FRI JUL 3 2015 .SYNOPSIS... SURFACE LOW PRESSURE WILL TRACK EAST ACROSS NC AND VA LATER TODAY AND TONIGHT...ALONG A FRONTAL ZONE THAT WILL LINGER OVER THE REGION THROUGH THE HOLIDAY WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1132 AM FRIDAY... CURRENT FORECAST PRETTY MUCH ON TRACK AS SHOWER/T-STORM COVERAGE WILL INCREASE THIS AFTERNOON AS MID LEVEL S/W APPROACHES THEN CROSSES THE REGION. 15Z MESO-ANALYSIS DEPICTS CONVECTIVE INHIBITION WANING...RESULTING IN A SLIGHT UPTICK IN CONVECTION OVER THE WESTERN-SOUTHERN PIEDMONT SINCE 14Z. THE MID LEVEL S/W CURRENTLY LIFTING E-NE OUT OF EASTERN TN AND SHOULD CROSS NEAR OR TO OUR NORTH THIS AFTERNOON. SINCE FEATURE CROSSING DURING PRIME HEATING AND AIR MASS QUITE MOIST (PRECIP WATER VALUES VARY BETWEEN 1.7-1.9 INCHES)...SHOULD SEE NUMEROUS SHOWERS AND STORMS DEVELOP BY MID AFTERNOON. 850-700MB WINDS ARE A BIT STRONGER THAN PROJECTED BY THE GFS...CLOSER TO THE NAM PROJECTIONS. LOW LEVEL JET ON THE ORDER OF 35KTS CROSSING AL-GA PER 12Z ANALYSIS WITH 50KT JET AT 700MB OVER CENTRAL AL. THIS FEATURE HAS INCREASED THE SHEAR OVER THIS PART OF THE COUNTRY RESULTING IN THE UPGRADE TO AN ENHANCED RISK THIS AFTERNOON. CLOSER TO HOME...THE ADDED SHEAR AND THE UNIDIRECTIONAL FLOW SHOULD CAUSE STORMS TO ORGANIZE INTO A BROKEN NORTH-SOUTH ORIENTATED BANDS. IN THIS TYPE OF ENVIRONMENT...THE SEVERE HAZARDS WILL EITHER BE FROM LOCALLY DAMAGING STRAIGHT LINE WINDS OR DAMAGING MICROBURSTS DUE TO PRECIP LOADING. AS MENTIONED IN EARLIER DISCUSSION...AN ISOLATED TORNADO RISK STILL EXISTS OVER MAINLY THE SOUTHERN CONTINUES AS THIS REGION IN CLOSER PROXIMITY TO THE LOW LEVEL JET AND BETTER NEAR SURFACE HELICITY. AFTERNOON TEMPS HIGHLY DEPENDENT ON CLOUD/CONVECTIVE COVERAGE THIS AFTERNOON. FEEL THAT CURRENT MAX TEMP FORECAST IS THE BEST CASE SCENARIO. IF CONVECTION CONTINUES TO BLOSSOM...MAY NEED TO ADJUST TEMPS DOWN A FEW DEGREES...ESPECIALLY ACROSS THE WEST AND SOUTH. TONIGHT...SCATTERED-NUMEROUS SHOWERS/STORMS SHOULD BEGIN TO DIMINISH FROM THE WEST-SW BY EARLY EVENING AS BEST UPPER LEVEL SUPPORT LIFTS FARTHER TO THE E-NE. EXPECT BULK OF ACTIVITY TO END PRIOR TO 03Z. STILL...A MOIST ATMOSPHERE COUPLED WITH MINOR PERTURBATIONS CROSSING OVERHEAD MAY TRIGGER/SUSTAIN ISOLATED SHOWERS ABOUT ANYWHERE THROUGH THE NIGHT. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 435 AM FRIDAY... THE MODELS CONTINUE TO INDICATE THE FRONTAL ZONE WILL REMAIN JUST TO THE NORTH OF CENTRAL NC ON SAT...WITH A SHARP LEE TROUGH AND A BREEZY SOUTHWEST FLOW AND MODEST MIXING OUT OF BOUNDARY LAYER MOISTURE OVER THE CAROLINAS. TEMPERATURES SHOULD CONSEQUENTLY WARM...INTO THE MID 80S TO LOW 90S...WITH THE FOCUS FOR AFTERNOON AND EVENING CONVECTION OVER THE NORTHERN AND NW NC PIEDMONT...IN CLOSEST PROXIMITY TO THE FRONTAL ZONE. CONTINUED SEASONABLY STRONG SW MID LEVEL FLOW IN THE 30-35 KT RANGE WILL FAVOR ORGANIZATION... AND DCAPE SHOULD BE HIGH WITH STEEP LOW LEVEL LAPSE RATES AND SURFACE DEWPOINT DEPRESSIONS AROUND 25 DEGREES...SO ANY STORMS THAT DO FORM WILL BE CAPABLE OF PRODUCING STRONG TO SEVERE WIND GUSTS...AND PERHAPS MARGINALLY SEVERE HAIL. ALTHOUGH THE MODELS INDICATE LIMITED QPF SAT NIGHT...THE FRONT IS FORECAST TO DRIFT SOUTH INTO CENTRAL NC LATE SAT NIGHT-EARLY SUN...SO A SLIGHT CHANCE OF A SHOWER OR STORM OVERNIGHT SEEMS JUSTIFIED. LOWS AGAIN AROUND 70. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 345 PM FRIDAY... A LOW AMPLITUDE SHORTWAVE CURRENTLY OVER THE US NORTHERN ROCKIES WILL DIVE INTO THE BASE OF THE BROAD EASTERN US TROUGH ON SATURDAY BEFORE ESSENTIALLY CUTTING OFF FROM THE FLOW AND DRIFTING UP THE APPALACHIANS ON SUNDAY AND MONDAY...WHILE THE PERSISTENT SURFACE FRONT/TROUGH FROM EARLIER IN THE WEEKEND REMAINS DRAPED ACROSS CENTRAL NC. THERE MAY BE SOME UNCERTAINTY IN INSTABILITY GIVEN CONSIDERABLE CLOUDINESS EXPECTED EARLY SUNDAY...BUT THE COMBINATION OF THE UPPER LOW...ALBEIT WEAK...AND SURFACE BOUNDARY AMIDST PW OVER 1.75" SHOULD LEAD TO NUMEROUS SHOWERS AND STORMS SUNDAY AND INTO SUNDAY NIGHT. BY THE MONDAY THE FRONT IS FORECAST SHIFT NORTH INTO VA AND THE FOCUS OF SHOWERS/STORMS MAY SHIFT MORE TOWARD THE COASTAL PLAIN. THE LOW/MID LEVEL FLOW IS MUCH WEAKER SUNDAY/MONDAY AND SEVERE STORMS MAY BE LESS OF A THREAT...BUT LOCALIZED FLOODING MAY REAR ITS HEAD...PARTICULARLY IN THE VICINITY OF THE BOUNDARY. CLOUDS AND PRECIP WILL LIKELY KEEP HIGHS LITTLE BELOW NORMAL IN THE MID TO UPPER 80S...SLIGHTLY WARMER ON MONDAY. BEYOND MONDAY... THERE ARE SOME SIGNS OF WARMING FOR THE MIDDLE OF NEXT WEEK AND A LITTLE LESS PRECIP COVERAGE AS THE PROGRESSIVE PATTERN EVENTUALLY YIELDS SOME REESTABLISHMENT OF THE SUB-TROPICAL RIDGE OVER THE SOUTHEAST US WITH A COLD FRONT DYING JUST TO OUR NORTH AROUND MIDWEEK. HOWEVER...THE OVERALL PATTERN IS NOT VERY AMPLIFIED AND TEMPS SHOULD REMAIN WITHIN A COUPLE DEGREES OF NORMAL. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 155 PM FRIDAY... AVIATION CONDITIONS WILL VARY ACROSS CENTRAL NC FROM VFR IN THE NORTHERN COASTAL PLAIN TO IFR/LOW END MVFR OVER THE WESTERN SECTIONS OF THE PIEDMONT. SCATTERED TO NUMEROUS SHOWERS AND STORMS WILL CROSS THE AREA FROM THE SW THROUGH THE AFTERNOON HOURS. THE STRONGER STORMS WILL PRODUCE WIND GUSTS 30-40KTS...MAINLY BETWEEN 20Z-02Z AND ACROSS THE SOUTHERN COUNTIES INCLUDING IN VICINITY KFAY. THE BULK OF THE CONVECTION WILL DIMINISH AFTER 02Z...LEAVING GENERALLY VFR CONDITIONS IN THEIR WAKE. THERE MAY BE POCKETS OF MVFR CEILING/FOG BY EARLY SATURDAY MORNING. EXPECT MAINLY VFR CONDITIONS SATURDAY AND IT WILL BE BREEZY (FOR MID SUMMER STANDARDS). NEAR SFC SW WINDS WILL BE 9-13KTS WITH GUSTS 20- 25KTS PROBABLE...WITH THE STRONGEST GUSTS ANTICIPATED IN THE VICINITY OF KFAY. WITH AFTERNOON HEATING...EXPECT SCATTERED CONVECTION TO OCCUR WITH THE GREATEST CONCENTRATION ACROSS THE NORTH IN VICINITY OF THE TRIAD TERMINALS AND POSSIBLY KRDU BETWEEN 21Z- 02Z. MOST OF THE CONVECTION WILL DIMINISH PRIOR TO MIDNIGHT. CONVECTION EXPECTED TO BE MORE NUMEROUS SUNDAY AS A MID LEVEL TROUGH CROSSES THE REGION. THIS WILL LEAD TO AREAS OF SHOWERS AND STORMS ALONG WITH MVFR CEILINGS/VISIBILITY. A RETURN TO MORE TYPICAL SUMMER PATTERN ANTICIPATED FOR MONDAY THROUGH WEDNESDAY WITH EARLY MORNING STRATUS/FOG GIVING WAY TO VFR CONDITIONS ASIDE FROM SCATTERED AFTERNOON-EARLY EVENING CONVECTION. WHILE VFR CONDITIONS WILL GENERALLY PREDOMINATE ACROSS CENTRAL NC THROUGH FRIDAY AFTERNOON...SCATTERED CONVECTION THIS AFTERNOON THROUGH THIS EVENING...AND AGAIN ON FRIDAY WILL CAUSE PERIODS OF MVFR CEILING AND VISIBILITIES. IN VICINITY OF THE STORMS...EXPECT GUSTY WINDS WITH GUSTS 30-40KTS LIKELY. A STALLED SURFACE FRONT NEAR THE VIRGINIA BORDER COUPLED WITH A SERIES OF UPPER LEVEL DISTURBANCES WILL CAUSE PERIODS OF SHOWERS AND STORMS ACROSS CENTRAL NC THROUGH TUESDAY. THE SCATTERED CONVECTION WILL BE MOST LIKELY IN THE AFTERNOON AND EVENING HOURS. IN VICINITY OF THE SHOWERS AND STORMS...EXPECT BRIEF INTERVALS OF MVFR CONDITIONS ALONG WITH WIND GUSTS UP TO 40 KTS. AT THIS TIME...IT APPEARS THAT THE CONVECTIVE COVERAGE WILL BE MOST NUMEROUS ON FRIDAY AND AGAIN MONDAY. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...WSS SHORT TERM...26 LONG TERM...22 AVIATION...WSS

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