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 070727 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 325 AM EDT TUE JUL 7 2015 .SYNOPSIS... AN UPPER TROUGH ACROSS THE SOUTHERN APPALACHIANS WILL LIFT AWAY FROM THE REGION TODAY. A RIDGE OF HIGH PRESSURE WILL THEN DEVELOP OVER THE SOUTHEAST AND STRENGTHEN THROUGH THE REMAINDER OF THE WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 915 PM MONDAY... ISOLATED/SCATTERED CONVECTION THAT DEVELOPED EARLIER THIS AFTERNOON HAS SHOWN A SLOW DOWNWARD TREND SINCE 00Z. THE EXCEPTION IS A BROKEN NARROW BAND OF SHOWERS WITH ISOLATED T-STORMS WHICH EXTEND FROM EAST OF THOMASVILLE TO NEAR ROXBORO. THIS BAND OF CONVECTION OCCURRING ALONG A WEAK 850-700MB TROUGH WITH SOME ADDITIONAL SUPPORT ALOFT FROM A VORT AXIS LIFTING N-NE ACROSS WESTERN NC. DUE TO THE PRESENCE OF THIS FEATURE INTERACTING WITH THE MOISTURE AVAILABLE AND LOW LEVEL (THOUGH WEAK) INSTABILITY...SHOULD SEE ISOLATED-SCATTERED CONVECTION PERSIST WEST OF HIGHWAY THROUGH THE EVENING HOURS WITH A DECREASE IN COVERAGE DURING THE OVERNIGHT HOURS. LATER TONIGHT...EXPECT TO SEE AREAS OF STRATUS ONCE AGAIN DEVELOP THOUGH EXPECT IT TO BE RELATIVELY THIN AND BRIEF IN DURATION. MIN TEMPS 68-73. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 335 PM MONDAY... EXPECT A PERIOD OF EARLY MORNING STRATUS TO START THE DAY WITH CLOUDS LIFTING AND INTERVALS OF SUNSHINE ARRIVING TOWARD MID TO LATE MORNING. CONVECTIVE COVERAGE ON TUESDAY SHOULD AGAIN BE LIMITED AS THE UPPER TROUGH LIFTS NORTH SOMEWHAT AND THE AIR MASS DRIES OUT WITH PW VALUES DROPPING 0.25 TO 0.50 INCHES FROM MONDAY AFTERNOON TO TUESDAY AFTERNOON. A WEAK SURFACE TROUGH ORIENTED SOUTHWEST ACROSS THE PIEDMONT COULD HELP TO INITIATE WIDELY SCATTED CONVECTION. GIVEN WEAK FLOW AND GENERALLY WEAK INSTABILITY...SEVERE WEATHER THREAT APPEARS MINIMAL. WILL INCLUDE SLIGHT CHANCE POPS MAINLY ACROSS THE EAST FOR TUESDAY AFTERNOON AND EVENING. THICKNESS VALUES INCREASE A BIT AS HEIGHTS RISE SLIGHTLY. THIS WILL SUPPORT HIGHS IN THE 89 TO 94 RANGE. -BLAES && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 325 AM TUESDAY... THU: THE WEAK PIEDMONT SURFACE TROUGH WILL HOLD OVER CENTRAL NC... WHILE THE SYNOPTIC FRONTAL ZONE SETTLES SOUTHWARD INTO VA. EXPANSIVE MID LEVEL RIDGING FROM THE LOWER MISS VALLEY ACROSS THE SOUTHEAST STATES CONTINUES TO SLOWLY RETROGRADE WHILE SUPPRESSING THE WESTERLIES TO OUR NORTH. ABUNDANT HEATING IS ASSURED.... WHICH WILL PUSH THICKNESSES UP TO 5-10 M ABOVE NORMAL... INDICATING HIGHS IN THE LOWER-MID 90S. FALLING DEWPOINTS WITH MIXING BY AFTERNOON SHOULD KEEP HEAT INDICES BELOW CRITICAL VALUES OVER MUCH OF THE CWA (ALTHOUGH THEY MAY EXCEED 100F BRIEFLY IN THE SE CWA). GIVEN THE DEEP LAYER SUBSIDENCE AND NEAR-NORMAL PW... ANY SUBSTANTIAL RAIN CHANCES WILL BE VERY LOW AND CONFINED TO THE EXTREME NORTH... POTENTIALLY ALONG OUTFLOW EMANATING FROM CONVECTION ALONG THE FRONT (PERHAPS ENHANCED BY A LOW CROSSING MD/DE)... AND ALONG AN INLAND- MOVING SEA BREEZE LATE IN THE DAY. FRI: THE SYNOPTIC FRONT TO THE NORTH APPEARS LIKELY TO DIP NEAR OR JUST INTO NE NC... WITH A RESIDUAL OUTFLOW POTENTIALLY DROPPING FURTHER SOUTH WELL INTO NORTH CENTRAL NC... WHILE ALOFT... THE MID LEVEL ANTICYCLONE CENTER CONTINUES TO DRIFT WESTWARD OVER THE LOWER MISS VALLEY. WITH THE SUBSEQUENT TILT/DIP IN THE WESTERLIES DOWN THE MIDATLANTIC COAST... MODELS DO TREND TOWARD A BIT MORE WEAK SHORTWAVE ENERGY TRACKING SOUTHEASTWARD BRUSHING NE NC FRI NIGHT... ALTHOUGH THE PROJECTED INSTABILITY SHOULD BE LOW (MUCAPE UNDER 750 J/KG ON THE GFS)... AND PW WILL ONLY BE SLIGHTLY ELEVATED OVER THE ERN CWA. WILL PLACE LOW CHANCE POPS ACROSS THE NORTH/NE CWA AND IN THE COASTAL PLAIN... ALONG THE WEAK SURFACE TROUGH. THICKNESSES WILL AGAIN BE 5-10 M ABOVE NORMAL... SO EXPECT HIGHS ONCE AGAIN IN THE LOW-MID 80S. LOWS 70-74 WITH LINGERING ISOLATED POPS OVER THE FAR NORTH AND NORTHEAST OVERNIGHT. SAT-MON: THE COMBINATION OF THE BUILDING RIDGE OVER THE SRN PLAINS AND UP THE FRONT RANGE OF THE ROCKIES AND RESULTING STRENGTHENING NW FLOW FROM THE UPPER MIDWEST THROUGH THE LOWER GREAT LAKES TO THE MIDATLANTIC COAST WILL PLACE NC IN A MORE ACTIVE AND VOLATILE WEATHER PATTERN... HIGHLIGHTED BY POCKETS OF MID LEVEL SHORTWAVE ENERGY CROSSING OUR REGION IN NW STEERING FLOW... TRACKING ALONG THE OLD DIFFUSE SURFACE FRONTAL ZONE. NORTHERN AND EASTERN PORTIONS OF THE FORECAST AREA SHOULD SEE THE BEST CHANCES FOR CONVECTION... ORIGINATING IN A HIGHLY UNSTABLE ENVIRONMENT OVER THE MIDWEST AND THE OH VALLEY MOVING SOUTHEASTWARD OVER VA/NC. WHILE WE CAN`T ACCURATELY TRACK SPECIFIC FEATURES AT THIS RANGE... THE IMPROVING SHEAR AND INSTABILITY ALONG WITH GREATER DYNAMIC FORCING FOR ASCENT SUPPORT BOOSTING POPS TO SLIGHTLY ABOVE CLIMATOLOGY DURING THIS PERIOD... AND NOT NECESSARILY PEAKING IN THE TYPICAL LATE-DAY TIME FRAME EITHER... AS HIGH LAPSE RATES WITHIN AN UPSTREAM EML MAY SUSTAIN NOCTURNAL CONVECTION AS IT MOVES SOUTHEAST. STILL EXPECT ABOVE NORMAL THICKNESSES TO EQUATE TO WARM TEMPS TOPPING OUT DAILY IN THE LOWER TO MID 90S... AND THE THREAT OF 100+F HEAT INDEX VALUES PARTICULARLY FROM THE TRIANGLE TO THE SOUTH AND EAST WILL LINGER INTO EARLY NEXT WEEK. -GIH && .AVIATION /00Z TUESDAY THROUGH FRIDAY/... AS OF 140 AM TUESDAY... VFR CONDITIONS FOR MOST OF THE REMAINDER OF THE NIGHT...ALTHOUGH A LITTLE STRONGER FLOW JUST ABOVE THE SURFACE OVER THE COASTAL PLAIN MAY LEAD TO SOME STRATUS BY 10-12Z. HOWEVER...MODEL GUIDANCE ISN`T REALLY INDICATING MUCH MORE THAN JUST A FEW PATCHES OF IFR STRATUS...SO THE LATEST TAF WILL REFLECT LESS IN THE WAY OF RESTRICTIONS. WHATEVER LOW CLOUDS THAT DO FORM WILL BURN OFF BY 14Z...AND SCATTERED CU IN THE 3-4K FT RANGE WILL DEVELOP FOR THE AFTERNOON HOURS. WITH DRIER AIR ON CENTRAL NC...ONLY WIDELY SCATTERED SHOWERS AND ISOLATED STORMS ARE EXPECTED OVER THE COASTAL PLAIN...PRIMARILY IN THE VICINITY OF KFAY AND/OR KRWI AFTER 18Z. OUTLOOK...MOSTLY VFR CONDITIONS THROUGH THE END OF THE WEEK AS HIGH PRESSURE DOMINATES THE REGION. SOME AFTERNOON STORMS ARE POSSIBLE EACH DAY...ALONG WITH EARLY MORNING VSBY RESTRICTIONS. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...WSS SHORT TERM...BLAES LONG TERM...HARTFIELD AVIATION...22

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