000 FXUS61 KPHI 051404 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1005 AM EDT SUN JUL 5 2009 .SYNOPSIS... LOW PRESSURE MOVING OUT OF THE LOWER OHIO VALLEY WILL MOVE EAST AND PASS OFF THE COASTS OF VIRGINIA AND NORTH CAROLINA EARLY ON MONDAY. A WEAK FRONTAL BOUNDARY FROM THE NORTHWEST IS EXPECTED TO ARRIVE ON MONDAY NIGHT. HIGH PRESSURE SHOULD FOLLOW FOR THE MIDDLE AND LATE PARTS OF THE NEW WEEK. A COLD FRONT FROM THE NORTHWEST MAY ARRIVE LATE ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HAVE SENT A QUICK UPDATE TO THE ZONE FCST MAINLY FOR COSMETIC WORDING CHANGES. OVERALL, THE FCST LOOKS TO BE ON TRACK WITH THE LOW EXPECTED TO BRING ANY EFFECTS MAINLY TO SRN PORTIONS OF THE REGION. THE 00Z NAM AND THE 12Z ECMWF AND NOW THE 00Z ECMWF ARE HANDLING THE SYSTEM APPROACHING LOCALES TO OUR SOUTH IN A REASONABLY SIMILAR WAY THROUGH TODAY. BASICALLY, THE GFS ALSO HAS JOINED THE CLUB, ALTHOUGH IT HAS BEEN THE LAST TO COME AROUND TO THE CONSENSUS SOLUTION. WE WILL CONTINUE TO OPERATE WITH A ECMWF/NAM/CONTINUITY APPROACH TO THE NEAR TERM. SOME ISENTROPIC LIFT BETWEEN I300 AND I305 CONTINUES TO BE PROGGED INTO THE SOUTHERN PART OF THE FORECAST AREA LATER TODAY AS DO SOME UPPER LEVEL Q-VECTOR CONVERGENCE AND LOWER LEVEL FRONTOGENESIS. INSTABILITY, AS FORECAST BY THE NAM 1 KM MOST UNSTABLE CAPE AND NAM BUFKIT SOUNDINGS, DOES NOT SEEM TO BE IN PLAY. IF WE TRULY ARE IN A COOL-SEASON PRECIPITATION PATTERN HERE, THEN THE SUPERIOR MODEL WITH REGARD TO QPF IS THE ECMWF. THE 12Z RUN WAS GIVING NO PRECIPITATION THIS PERIOD ANYWHERE IN OUR AREA, WHILE THE 00Z ECMWF AND THE NAM ARE GIVING UNDER A TENTH OF AN INCH FAR SOUTH. CONTINUITY WOULD HAVE US UNDERCUT THE MET POPS IN THE FAR SOUTHERN ZONES, BUT THE PRESENCE OF SOME /ADMITTEDLY, NOT A LOT/ SYNOPTIC AND MESOSCALE FORCING WILL HAVE US TWEAK THE POPS UP JUST A BIT FAR SOUTH. WE ALSO ARE GOING TO SHAVE OFF A BIT OF THE NORTHERN EDGE OF OUR SLIGHT CHANCE POPS. NONE OF THIS CONSTITUTES MUCH OF A CHANGE. EXPECT MAINLY HIGH CLOUDS NORTH, MID CLOUDS CENTRAL AND LOWER TO MID LEVEL CLOUDS SOUTH. MAX TEMPERATURES TODAY WILL BE A COMBINATION OF CONTINUITY AND THE MET AS THEY ARE VERY CLOSE AND SEEM REASONABLE. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... THE BEST OF THE FORCING DOWN SOUTH, SUCH AS IT IS, IS TONIGHT. THERE IS A CONTINUED LACK OF SIGNIFICANT FORECAST INSTABILITY. WE DO NOT EXCEED CHANCE POPS IN THE SOUTH, AND WE CARRY NO POPS FURTHER NORTH. THE ECMWF IS A BIT SLOWER MOVING THE SYSTEM OUT THAN THE NAM, AND THAT SUPPORTS THE SILENT 20 POPS WE HAVE BEEN CARRYING FOR THE SOUTHEASTERN ZONES DURING MONDAY MORNING. AFTER THAT, ANOTHER MID LEVEL VORTEX IS PROGGED TO DROP OUT OF THE CANADIAN GREAT LAKES REGION AND INTO NEW ENGLAND FROM MONDAY AFTERNOON INTO TUESDAY. THE LATEST MODEL RUNS DO NOW AGREE THAT THERE WILL BE SOME INSTABILITY FOR THIS SYSTEM TO WORK WITH, BUT THEY DO NOT AGREE ON THE PLACEMENT/TIMING OF THE ASSOCIATED SURFACE BOUNDARY. WITH THE VORTEX PRESENTLY PROGGED TO MOVE NO FURTHER SOUTH THAN UPSTATE NEW YORK, WE MAINTAIN ONLY THE SLIGHT CHANCE POPS THAT WE HAVE BEEN CARRYING, BUT WE DO ADD THUNDER TO THE MIX. TEMPERATURES TONIGHT THROUGH MONDAY NIGHT ARE A BLEND OF CONTINUITY, THE MAV AND THE MET SINCE THE THREE ARE REASONABLY CLOSE. ON TUESDAY, WE ARE SHYING AWAY FROM THE WARMER MAV GUIDANCE GIVEN THE ONGOING PATTERN, BUT WE HAVE REDUCED THE DISCONTINUITY BETWEEN THE COAST AND INLAND AREAS BECAUSE OF A FORECAST OFFSHORE FLOW. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... IT LOOKS AS THOUGH WE WILL LOSE THE UPPER LEVEL TROUGH BRIEFLY DURING THE LATE PART OF THE WEEK. HOWEVER, BOTH THE GFS AND THE ECMWF SUGGEST ITS RETURN DURING THE COURSE OF NEXT WEEKEND, ALTHOUGH IT MAY NOT BE AS PRONOUNCED AS THE CURRENT ONE. SURFACE HIGH PRESSURE IS EXPECTED TO BUILD INTO OUR REGION FROM THE WEST ON WEDNESDAY. THE CENTER OF THE HIGH SHOULD PASS OVER OR NEAR OUR REGION ON THURSDAY, BEFORE MOVING OUT TO SEA ON FRIDAY. WE WILL FORECAST DRY WEATHER FOR EACH OF THE THREE DAYS. A COLD FRONT IS ANTICIPATED TO DROP DOWN FROM THE NORTHWEST ON SATURDAY, AS AN UPPER LEVEL TROUGH AGAIN BEGINS TO ESTABLISH ITSELF OVER THE EASTERN STATES. WE WILL INCLUDE A CHANCE FOR AFTERNOON AND EVENING THUNDERSTORMS. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... FLYING CONDITIONS ARE FORECAST TO REMAIN WELL IN THE VFR RANGE TODAY AND TONIGHT. A WEAK STORM PASSING TO OUR SOUTH TODAY AND EARLY TONIGHT WILL BRING HIGH LEVEL MOISTURE TO THE AREA, MORE SO SOUTH THAN NORTH, WITH SLIGHTLY LOWER AND THICKER CEILINGS SOUTH. OVER NORTHERN AREAS, KABE WILL BE ON THE FRINGES OF THIS HIGHER CLOUD COVER. PERHAPS THE BIGGER STORY WILL BE THE WIND DIRECTION. SPEEDS ARE FORECAST TO BE MUCH LESS THAN SATURDAY; WITH MORE CLOUDS, THERE WILL BE LESS MIXING, AND ALSO THE GRADIENT IS MUCH FLATTER TODAY. REGARDING DIRECTIONS, WINDS ARE EXPECTED TO START OFF WITH A NORTHERLY COMPONENT AS THE HIGH IS STILL SLIGHTLY TO THE WEST OF THE AREA AS OF 06Z, THEN BACK TO WEST AND EVENTUALLY SOUTHWEST OR SOUTH BY MIDDAY. THE WINDS MAY EVEN BECOME MORE SOUTHEAST AT TERMINALS SUCH AS KACY, KMIV AND KILG WHERE A SEA BREEZE AND / OR BAY BREEZE MAY BECOME A FACTOR, AS THE 850 HPA FLOW IS LIGHTER TODAY. MODEL GUIDANCE INDICATES THAT THE BEST LIFT AND MOISTURE WILL BE SOUTH OF OUR TAF SITES THIS AFTERNOON AND THIS EVENING, SO ANY MENTION OF SHOWERS WILL CONTINUE TO BE LEFT OUT OF THE TAFS. PERHAPS A FEW SHOWERS CANNOT BE RULED OUT FOR KMIV AND KACY, HOWEVER THE CHANCE IS SMALL ENOUGH AT THIS TIME TO NOT INCLUDE THE MENTION AT THESE SITES. OUTLOOK... THE AREA OF LOW PRESSURE IS FORECAST TO MOVE TO OUR SOUTH AND EAST OVERNIGHT TONIGHT INTO MONDAY, TAKING THE CLOUDS AND MOISTURE WITH IT. THE WINDS WILL BE MAINLY LIGHT AND VARIABLE LATER TONIGHT INTO MONDAY MORNING, BUT ANY TAF SITES SHOWING A PREFERRED DIRECTION ARE EXPECTED TO SHOW A NORTHWEST OR NORTH DIRECTION. A NORTHWEST FLOW ALOFT WILL ONCE AGAIN ALLOW A FEW WEATHER DISTURBANCES TO MOVE THROUGH, AND THESE MAY BE ENOUGH TO ALLOW FOR AN ISOLATED SHOWER OR THUNDERSTORM DURING THE DIURNALLY-FAVORABLE AFTERNOON AND EVENING HOURS ON TUESDAY. AT THE SURFACE, HIGH PRESSURE IS FORECAST TO BUILD IN WEDNESDAY AND THURSDAY. OVERALL, NO SIGNIFICANT WEATHER IS ANTICIPATED FOR THE COMING WEEK AND CONDITIONS SHOULD BE MAINLY VFR. && .MARINE... WEAK SURFACE HIGH PRESSURE OVER THE AREA EARLY THIS MORNING WILL ALLOW FOR LIGHTER WINDS TODAY AS OPPOSED TO SATURDAY. A WEAK MAINLY UPPER LEVEL WEATHER DISTURBANCE WILL PASS TO OUR SOUTH LATER TODAY INTO TONIGHT; HOWEVER, THERE IS SOMEWHAT OF A SURFACE REFLECTION ALSO, WHICH WILL CAUSE WIND DIRECTIONS TO SHIFT AROUND. ALSO, THIS DISTURBANCE MAY BRING SCATTERED SHOWERS TO THE SOUTHERN MARINE ZONES INTO EARLY TONIGHT. YET ANOTHER UPPER LOW IS EXPECTED TO BUILD DOWN FROM THE NORTH MONDAY, WITH WEAK SURFACE HIGH PRESSURE UNDERNEATH. GENERALLY DRY WEATHER IS EXPECTED, WITH THE EXCEPTION OF SOME ISOLATED TO SCATTERED CONVECTION WITH ANY PIECES OF UPPER LEVEL ENERGY WHICH ROTATE AROUND THE LOW. THIS WOULD BE MORE LIKELY IN THE DIURNALLY-FAVORABLE AFTERNOON AND EVENING HOURS ON TUESDAY. THE RIP CURRENT RISK WILL CONTINUE TO BE LOW TODAY, DESPITE THE PROXIMITY OF THE FULL MOON ON TUESDAY, ESPECIALLY SINCE THE LONG PERIOD SWELL SATURDAY MORNING HAS NOW TRENDED TO A SHORTER PERIOD. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...NIERENBERG/DELISI/IOVINO NEAR TERM...NIERENBERG/DELISI SHORT TERM...DELISI LONG TERM...IOVINO AVIATION... MARINE...