FXUS61 KMHX 200752 AFDMHX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 350 AM EDT TUE JUL 20 2010 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE OFFSHORE OVER THE NEXT SEVERAL DAYS. A TROUGH OF LOW PRESSURE WILL MEANWHILE LINGER JUST INLAND FROM THE REGION THROUGH THE MIDDLE OF THE WEEK. A WEAK COLD FRONT WILL APPROACH THE AREA WEDNESDAY NIGHT AND WASH OUT ACROSS NORTHERN SECTIONS THURSDAY. THE TYPICAL SUMMER TIME OFFSHORE HIGH PRESSURE AND INLAND TROUGHING PATTERN WILL DOMINATE FRIDAY THROUGH THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 3AM TUE...MAIN ISSUE TODAY WILL BE HEAT AND HUMIDITY. IT IS NOTED THAT A HANDFUL OF LOCATIONS GENERALLY BETWEEN KOAJ AND KMQI BRIEFLY REACHED HEAT ADVISORY CRITERIA YESTERDAY. 850 TEMPS...LOW LVL THICKNESSES...AND MOS GUIDANCE ALL SUGGEST MAX TEMPS WILL BE A COUPLE DEGREES HOTTER IN MOST LOCATIONS TODAY WITH DEWPOINTS REMAINING SIMILAR IN THE MID 70S (SOME UPPER 70S NEAR THE SOUNDS AND NRN OBX). THIS SUPPORTS A FEW HOURS WITH INDEX VALUES OF 105-107 THIS AFTERNOON SO HAVE ISSUED THE ADVISORY ALL COUNTIES EXCEPT FOR OUR NW ZONES WHICH WILL HAVE BETTER MIXING/LOWER DEWPOINTS IN THE AFTERNOON...AND CARTERET/OBX HYDE DUE TO THE INFLUENCE OF ONSHORE SW FLOW THERE. CONVECTIVE CHANCES AGAIN A CHALLENGE TODAY WITH DIFFERENCES IN THE NWP GUIDANCE YET AGAIN. SUBSIDENCE BEHIND MID LEVEL SHORT WAVE CURRENTLY PUSHING OFFSHORE SHOULD KEEP THE AREA DRY THIS MORNING. HOWEVER...THE ABOVE MENTIONED HEAT WILL PRODUCE A HEALTHY AMOUNT OF SFC BASED CAPE THIS AFTERNOON. WITH THIS IN ADDITION TO A BIT MORE DIFFLUENT UPPER PATTERN OVER THE AREA BTWN AN ANTYICYCLONE SOUTH/SOUTHWEST OF THE AREA AND BROUGH TROUGHING TO OUR NORTH...WILL CONTINUE TO FORECAST LOW CHANCE POPS INLAND WITH SCHC NEAR THE IMMEDIATE COAST...WITH THE MAIN TRIGGER BEING THE SEA BREEZE. MAIN THREATS WOULD AGAIN BE STRONG GUSTY WINDS...BRIEF HEAVY DOWNPOURS...AND LIGHTNING. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... AS OF 330AM TUE...WE EXPECT ANY CONVECTION THAT DEVELOPS THIS AFTN TO WANE INTO AND THROUGH THE EVENING HOURS WITH LOSS OF HEATING. THE GFS BRINGS A BAND OF ISOLATED CONVECTION INTO THE AREA OVERNIGHT ASSOCIATED WITH THE INLAND TROUGH DRIFTING CLOSER TO THE COAST IN ADDITION TO ENERGY MOVING THROUGH THE MID LVL NW FLOW...BUT IT APPEARED TO BE AN OUTLIER SO HAVE HELD OFF ADDING POPS. LOWS WILL CONTINUE ABOVE NORMAL IN THE M-U70S (NR 80 OBX) IN PERSISTENT SW FLOW PATTERN. STRONG MID AND UPR ANTICYCLONE BEGINS TO TAKE ITS GRIP OVER THE SE STATES WED-THU. THIS SHOULD OVERALL LIMIT CONVECTIVE CHANCES TO ISOLATED TO WIDELY SCATTERED...THOUGH THERE APPEARS TO BE ONE NOTABLE CHANGE IN THE 00Z GUIDANCE. MOST OF THE LATEST NWP MODELS NOW SUGGEST A WEAK FRONT WILL APPROACH THE AREA WED NIGHT AND MOVE INTO THE NE PORTION OF THE AREA EARLY THU BEFORE WASHING OUT. THIS IS ASSOCIATED WITH A QUICK MOVING DEEP LAYERED TROUGH TO SWING FROM THE GREAT LAKES REGION ON WED THROUGH THE NE STATES INTO THU. BOTH THE GFS AND NAM SUGGEST AN AREA OF PREFRONTAL MSTR/CONVERGENCE WILL BRING A BAND OF SHOWERS/TSTMS THROUGH THE REGION WED NIGHT. GIVEN UNFAVORABLE DIURNAL CYCLE HAVE LIMITED POPS TO SCHC FOR NOW. THE DIFFUSE FRONT IN ADDITION TO HEATING/SEA BREEZE COULD ENHANCE CONVECTIVE POTENTIAL AGAIN THU AFTN...THOUGH MOST OF THE SUPPORTING MID LVL ENERGY IS EXPECTED TO SWING OFFSHORE LEAVING US MAINLY UNDER THE INFLUENCE OF STRONG RIDGING IN THE MID AND UPR LEVELS. WILL THUS KEEP POPS ISOLATED FOR THU. HEAT ADVISORIES MAY BE REQUIRED FOR PORTIONS OF THE AREA DURING THE SHORT TERM AS WELL...AS ABOVE NORMAL THICKNESSES/TEMPS COMBINE WITH HIGH DEWPOINTS AND HUMIDITIES. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... AS OF 330 AM TUE...HOT AND HUMID CONDITIONS WILL PEAK FRI-SAT AS THE UPPER RIDGE BUILDS OVER THE SE STATES. 850 MB TEMPS IN EXCESS OF 20C INDICATES THAT HIGHS FLIRTING WITH 100 DEG INLAND/LOW 90S ALONG THE COAST WILL BE POSSIBLE THROUGH AT LEAST SAT WITH DANGEROUS HEAT INDEX VALUES OF AROUND 105 DEGREES EXPECTED. UPPER RIDGE WILL INHIBIT CONVECTION...THOUGH ISOLATED DIURNAL CONVECTION POSSIBLE. HEIGHTS BEGIN TO SLOWLY FALL SUN-MON AS WEAK FRONTAL BOUNDARY APPROACHES FROM THE NORTH...SO EXPECT SUBTLE REPRIEVE FROM OPPRESSIVE HEAT AND HUMIDITY. CONVECTIVE CHANCES MAY ALSO INCREASE WITH THIS BUT GIVEN UNCERTAINTY IN LATE JULY FRONTS AT THIS TIME FRAME...WILL KEEP POPS IN THE SILENT 20 VARIETY FOR NOW. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... VFR EXPECTED TO PREVAIL AGAIN TODAY OUTSIDE OF SCT AFTN/EARLY EVENING CONVECTIVE ACTIVITY. THUNDERSTORM COVERAGE SHOULD A MORE LIMITED AND DIURNALLY DRIVEN LATE IN THE WEEK AS A STRONG UPPER RIDGE BUILDS OVER THE AREA. THE LOW LEVELS ARE FORECAST TO REMAIN MIXED AT NIGHT LIMITING THE POTENTIAL FOR WIDESPREAD DENSE FOG. && .MARINE... HIGH PRES OFFSHORE AND TROUGH INLAND WILL CONTINUE TO PRODUCE PERIODS OF SCA CONDITIONS FOR ALL BUT ALBEMARLE SOUND INTO WED NIGHT. CYCLE WILL BE SOMEWHAT DIURNALLY DRIVEN WITH STRONGER WINDS MAINLY LATE AFTN INTO OVERNIGHT HOURS. NAM12 AND GFS40 CONTINUE TO INDICATE WEAK BNDRY MOVING INTO NRN WATERS EARLY THU...LEADING TO WIND SHIFT THERE AND WEAKER PRES GRAD AND LIGHTER WINDS ALL WATERS. BNDRY QUICKLY DISSIPATES WITH FLOW RETURNING TO SRLY ALL WATERS THU NIGHT...THEN BERMUDA HIGH PATTERN RETURNS WITH SW WINDS GRADUALLY INCREASING FRI-SAT. WW3 AND LOCAL SWAN IN GOOD AGREEMENT MOST OF PERIOD AND GENERALLY AGREED WITH PREVIOUS FCST. THE COMBINATION OF MODERATE ONSHORE FLOW AND RESIDUAL SE SWELL WILL PRODUCE A MODERATE THREAT FOR DANGEROUS RIP CURRENTS TODAY FROM HATTERAS SOUTH ESPECIALLY ALONG THE SOUTH FACING BEACHES. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...HEAT ADVISORY FROM NOON TODAY TO 6 PM EDT THIS EVENING FOR NCZ045>047-080-081-090-092>094-098-103. MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR AMZ135-150- 156-158. SMALL CRAFT ADVISORY UNTIL 11 AM EDT THURSDAY FOR AMZ152-154. && $$ SYNOPSIS...MW NEAR TERM...MW SHORT TERM...MW LONG TERM...CQD/MW AVIATION...JME/JBM MARINE...JBM