468 FXUS61 KPHI 221320 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 920 AM EDT MON JUL 22 2013 .SYNOPSIS... A NEARLY STATIONARY FRONT WILL BE DRAPED ACROSS OUR AREA TODAY, THEN SETTLE TO OUR EAST TONIGHT. A SECONDARY FRONT IS SCHEDULED TO MOVE THROUGH OUR AREA EARLY WEDNESDAY, BUT WILL JOIN THE EARLIER FRONT AND STALL OFF THE COAST THURSDAY THROUGH SATURDAY. A WEAK AREA OF HIGH PRESSURE BUILDS ACROSS TO OUR NORTH LATE WEDNESDAY INTO FRIDAY, THEN THE NEXT COLD FRONT IS FORECAST TO ARRIVE ON SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WE ADDED SOME PATCHY FOG FOR THE NEW JERSEY COASTAL STRIP AS THERE HAS BEEN SOME REPORTS OF FOG RIGHT NEAR THE BEACH IN SOME LOCATIONS. THERE IS SOME LIGHT FOG/HAZE INLAND, BUT THE THICKEST FOG LOOKS TO BE RIGHT NEAR THE COAST. WE ONLY KEEP IT THROUGH THE MORNING, BUT WILL REVISIT LATER TO SEE IF WE NEED TO KEEP IT IN LONGER. OTHERWISE, MOSTLY CLOUDY, WITH HAZY CONDITIONS THIS MORNING AND SCATTERED SHOWERS DEVELOPING THROUGH THE DAY. AN H5 TROF AXIS WILL BE POSITIONED TO THE W, A STALLED FRONTAL BOUNDARY NEAR BY AND SOME S/WV ENERGY WILL MOVE ACRS THE AREA. ALL OF THIS MEANS WE WILL SEE SOME SHOWERS AND PSBLY SOME TSTMS ONCE AGAIN, BUT THE EXACT TIMING AND LOCATION IS DIFFICULT TO NAIL DOWN, DUE TO THE INHERENT MDL DIFFS WITH THE S/WVS. THE GFS DOES APPEAR TO BE SUFFERING FROM SOME CONVECTIVE FEEDBACK PROBS WHICH WILL IMPACT ITS SOLN, BUT NEVERTHELESS ALL OF THE MDLS INDICATE SOME PRECIP FOR TODAY, WITH THE BEST CHCS MOST LIKELY IN THE SECOND HALF OF THE DAY AND PROBABLY OVER NRN AREAS. DEPENDING ON CLOUD COVER AND SHOWER ACTIVITY, THAT COULD HAVE AN IMPACT ON TEMPS AS WELL AND HAVE TRENDED TWD A MIDDLE OF THE ROAD SOLN BETWEEN THE WARMER MAV (WHICH HAS BEEN DOING BETTER OF LATE) AND THE COOLER MET. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/... DEPENDING ON WHICH MDL YOU BELIEVE, THE EARLY PORTION OF THE SHORT TERM COULD BE THE WETTEST PD...OR NOT...AGAIN ALL DEPENDENT ON TIMING AND STRENGTH OF S/WVS MOVG THRU THE AREA. HOWEVER, BUT POPS SHOULD DECREASE TWD DAYBREAK. MOS GUID WAS IN BETTER AGREEMENT HERE AND WAS GENLY FOLLOWED. && .LONG TERM /TUESDAY THROUGH SUNDAY/... THE OVERALL SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL TROUGH IN THE EAST. THIS FEATURE WILL ADJUST A FEW TIMES IN AMPLITUDE, WHICH WILL RESULT IN SOME FRONTAL BOUNDARIES DRIVING SOUTHEASTWARD. THE TIMING OF THE SHORT WAVE ENERGY TRAVELING WITHIN THE FLOW IN THE UPPER-LEVEL TROUGH WILL BE THE MAIN TRIGGER TO INITIATE SOME SHOWERS AND THUNDERSTORMS. WHILE THERE IS SOME UNCERTAINTY REGARDING THE DETAILS DUE TO THE TIMING OF SUCH FEATURES, IT DOES APPEAR THAT TUESDAY IS THE DAY TARGETED FOR BETTER CONVECTIVE CHANCES WITH MUCH LESSER CHCS WEDNESDAY AND THURSDAY. OVERALL, THIS PATTERN WILL RESULT IN CONTINUED RELIEF FROM LAST WEEKS OPPRESSIVE HEAT AND HUMIDITY. FOR TUESDAY AND WEDNESDAY...A MAIN IMPULSE IS FORECAST TO LIFT ACROSS OUR AREA DURING TUESDAY WITH A SURFACE BOUNDARY IN THE VICINITY. THERE SHOULD BE A SURFACE LOW ASSOCIATED WITH THE MID LEVEL FEATURE, WHICH WILL TEND TO ENHANCE THE PRECIPITATION CHCS SOME. THE INCREASING ASCENT WITH THE MID LEVEL SHORT WAVE WILL ACT UPON A MOIST AND UNSTABLE ENVIRONMENT. AS A RESULT, WE ARE ANTICIPATING SHOWERS AND SCATTERED THUNDERSTORMS TO BECOME MORE NUMEROUS DURING THE DAY. THE MOST ORGANIZED ACTIVITY MAY END UP BEING NEAR A WEAK SURFACE LOW THAT TRACKS ACROSS THE CWA. A PLUME OF PW VALUES OF 2 INCHES REMAINS AHEAD OF THIS FEATURE, THEREFORE BANDS OF SHOWERS AND SOME THUNDERSTORMS WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAIN. THE STEERING FLOW STILL APPEARS TO BE 20 KNOTS OR LESS TUESDAY, THEREFORE SLOW MOVING CONVECTIVE ELEMENTS MAY PRODUCE LOCALIZED FLOODING. THERE COULD BE SOME STRONG CONVECTION IF POCKETS OF HIGHER INSTABILITY CAN BE ACHIEVED, HOWEVER GIVEN THE WEAKER FLOW ANY SEVERE THREAT LOOKS LOW ATTM. A LOCALIZED DOWNBURST CANNOT BE RULED OUT THOUGH TUESDAY AFTERNOON DUE TO WATER LOADING WITHIN SOME PULSE STORMS. THE CONVECTION SHOULD TAPER OFF IN THE EVENING AS MOST APPEARS TO BE AIDED BY DAYTIME HEATING. THEREFORE, CARRIED CHC TO LIKELY POPS DURING THE DAY THEN TAPERED TO CHC IN THE EVENING THEN SLIGHT CHC EVERYWHERE OVERNIGHT. IT NOW APPEARS THAT THE MAIN SHORT WAVE LIFTS NORTHEAST OF OUR AREA FOR WEDNESDAY WITH WEAK SURFACE HIGH PRESSURE APPROACHING FROM THE GREAT LAKES. THIS WOULD RESULT IN THE COLD FRONT ALREADY TO OUR EAST AND A DRY DAY WITH A NOTABLE DRIER NORTHWESTERLY FLOW. THE ECMWF/ECMWF MEAN/UKMET AND NAM APPEAR TO BE THE MOST CONSISTENT AND AGREEABLE GUIDANCE WITH THIS FEATURE AND ITS ASSOCIATED COLD FRONT. THEREFORE, SOME OF THE MODEL GUIDANCE SUGGESTS THAT THE SURFACE DEW POINTS DROP INTO THE 50S IN THE AFTERNOON FOR ABOUT THE NORTHERN HALF OF THE CWA. IF CORRECT, THIS WILL BE A RATHER NOTABLE CHANGE FROM THE OPPRESSIVE HUMIDITY OF LAST WEEK. THE SURFACE FRONT SHOULD BE FAR ENOUGH SOUTH AND EAST OF THE AREA, WHICH RESULTS IN A DRIER WEDNESDAY NIGHT. WE DID LOWER THE DEW POINTS SOME, HOWEVER DID NOT GO AS LOW AS SOME OF THE GUIDANCE IS SHOWING GIVEN SOME LOWER CONFIDENCE WITH THE SOUTHERN EXTENT OF THE PUSH OF DRIER AIR. FOR THURSDAY AND FRIDAY...THERE STILL REMAINS AT LEAST SOME UNCERTAINTY, ESPECIALLY REGARDING THE PLACEMENT OF A STALLED OUT SURFACE FRONT. IT APPEARS THE GUIDANCE IS EDGING THIS BOUNDARY FARTHER EAST WHICH WOULD RESULT IN LESS CHCS FOR CONVECTION. THERE STILL IS THE UPPER-LEVEL TROUGH IN PLACE, HOWEVER THE AMPLITUDE OF THIS DIFFERS SOME AMONG THE GUIDANCE. IF WE CAN MAINTAIN A PLUME OF HIGHER PW VALUES ESPECIALLY CLOSER TO THE COAST, THIS MAY ASSIST IN SOME MAINLY AFTERNOON AND EVENING CONVECTION. SOME GUIDANCE HOWEVER SUGGESTS THE PW VALUES DROP SIGNIFICANTLY TO PUT A LID ON CONVECTION BOTH DAYS. ON THE OTHER HAND, SOME GUIDANCE INDICATES A LEAD SHORT WAVE SHARPENING UP ACROSS THE MID ATLANTIC FRIDAY, WHICH WOULD BRING INCREASED CHCS FOR SHOWERS/THUNDER TO OUR AREA. FOR NOW, DID NOT GO ANY HIGHER THAN LOW CHC POPS GIVEN THE LOWER CONFIDENCE WITH THE DETAILS/TIMING. FOR SATURDAY AND SUNDAY...THE UPPER-LEVEL TROUGH IS FORECAST TO AMPLIFY ACROSS THE MIDWEST AND GREAT LAKES SATURDAY, THEN ACROSS THE NORTHEAST SUNDAY. THIS WILL DRIVE ANOTHER COLD FRONT INTO OUR AREA SUNDAY, WITH A CHC FOR SOME SHOWERS AND THUNDERSTORMS. AS OF NOW, THE BEST LARGE SCALE LIFT WITH THE UPPER-LEVEL TROUGH MAY TRACK TO OUR NORTH WHICH WOULD LIMIT THE OVERALL PRECIPITATION CHCS. OVERALL, POPS WERE CLOSE TO THE 00Z WPC GUIDANCE. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TAFS REMAIN VARIABLE THIS MORNING FROM SITE TO SITE. IFR/MVFR CONDITIONS PERSIST FOR TTN/PNE/ACY AND WILL CONTINUE FOR ANOTHER COUPLE OF OURS UNTIL THE SUN IS ABLE TO WORK THROUGH THE CLOUDS AND MIX THINGS OUT. ONCE THIS HAPPENS, A GENERAL VFR FCST IS EXPECTED. THE REST OF THE TAF SITES HAVE REMAINED VFR SO FAR THIS MORNING, AND ARE CURRENTLY EXPECTED TO REMAIN SO. -SHRA WILL MOVE IN FOR ALL TAF SITES BY AFTERNOON. IT SHOULD BE LIGHT ENOUGH FOR MAINLY VFR CONDS. HOWEVER SOME LOWER CIGS/VSBYS CAN NOT BE RULED OUT, CERTAINLY IF THERE ARE TSRA. BY NIGHTFALL, THERE COULD BE SOME ADDITIONAL -SHRA OR A MORE WIDESPREAD MVFR CIG AND VSBY EVENT. BUT ONCE AGAIN, THE MDLS HAVE OVERDONE THIS FOR SEVERAL NIGHTS, SO UNLESS THERE IS ONGOING RAIN, CONFIDENCE IS QUITE LOW. THE WIND WILL BE E TO SE AND LESS THAN 10 KT DURG THE DAY....DECREASING TO LESS THAN 5 KT AT NIGHT. OUTLOOK... TUESDAY...MAINLY VFR. HOWEVER, EARLY MORNING MVFR/IFR CONDITIONS ARE POSSIBLE DUE TO SOME LOW CLOUDS/FOG. SOME SHOWERS AND THUNDERSTORMS ARE EXPECTED, ESPECIALLY IN THE AFTERNOON, WITH SUB-VFR CAN OCCUR IN HEAVIER SHOWERS/THUNDERSTORMS. WEDNESDAY...VFR. NORTHWEST WINDS 10-15 KNOTS. THURSDAY AND FRIDAY...MOSTLY VFR, HOWEVER THERE IS A CHANCE FOR LOCAL MVFR FOG DURING THE EARLY MORNING HOURS. && .MARINE... WE HAVE ADDED SOME PATCHY FOG FOR THE NEW JERSEY COASTAL WATERS AND LOWER DELWARE BAY AS THERE HAS BEEN SOME REPORTS OF SOME FOG ALONG THE WATERS. WE ONLY KEPT IT THROUGH THE MORNING, BUT WILL REVISIT LATER IN THE MORNING TO SEE IF WE NEED TO EXTEND IT OUT. OTHERWISE, RELATIVELY QUIET CONDS ON THE AREA WATERS WITH WK FLOW. SEAS WILL BE AROUND 3 FT AND WIND GENLY IN THE 10 15 KT RANGE. THEREFORE NO HEADLINES ARE EXPECTED DURG THE NEAR OR SHORT TERM PDS. OUTLOOK... THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH FRIDAY. A FRONTAL BOUNDARY LURKING NEAR THE AREA WILL BE JOINED BY A SECOND ONE EARLY WEDNESDAY. IT APPEARS THAT THIS BOUNDARY MAY THEN BE PUSHED FAR ENOUGH TO THE EAST. THIS WILL RESULT IN THE WINDS BECOMING NORTHERLY WEDNESDAY THROUGH FRIDAY AS WEAK HIGH PRESSURE BUILDS TO OUR NORTH. IT APPEARS THAT THE WAVEWATCH GUIDANCE IS ON THE HIGH SIDE TUESDAY INTO WEDNESDAY /SEEMS TO BE A PATTERN THIS WARM SEASON/, WHICH IS PROBABLY TIED TO THE GFS HAVING A MORE DEFINED SURFACE LOW. THEREFORE, WE SHAVED ABOUT A FOOT FROM THIS GUIDANCE. && .TIDES/COASTAL FLOODING... THE FULL MOON IS TODAY AND ASTRONOMICAL TIDES ARE RUNNING QUITE HIGH. WE WILL BE VERY CLOSE TO MINOR TIDAL FLOODING CRITERIA FOR THE EVENING TIDAL CYCLE AT A FEW SITES. A COASTAL FLOOD ADVISORY MAY BE NEEDED WITH LATER SHIFTS. WILL CONTINUE TO MONITOR. && .EQUIPMENT... THE KNEL /LAKEHURST/ TEMPERATURE DATA IS INACCURATE AND HAS BEEN SINCE ABOUT MARCH 9TH. IT IS RUNNING ABOUT 8 TO 10 DEGREES TOO WARM AND THE PROBLEM IS PARTICULARLY NOTICEABLE DURING THE DAYTIME HOURS. USE OF THIS INFORMATION BY THE NWS WAS SUSPENDED IN EARLY APRIL HERE AT MOUNT HOLLY WHERE WE NO LONGER POSTED THE INFORMATION IN OUR HOURLY WEATHER ROUND UP AND THE TWICE DAILY REGIONAL TEMPERATURE AND PRECIPITATION SUMMARY SENT AT 815 AM AND PM. WE ARE DEEPLY CONCERNED WITH RECENT MEDIA REPORTS CITING THIS ERRONEOUS DATA, AND IN SOME CASES ATTRIBUTING IT TO THE NWS. KNEL IS A DOD SITE AND HAS BEEN NOTIFIED MULTIPLE TIMES THAT THEIR DATA IS IN ERROR. NO CORRECTIVE ACTION HAS BEEN TAKEN THAT WE ARE AWARE OF. PLEASE BE EXTREMELY CAUTIOUS WITH THIS DATA SET. THE NWS IN MOUNT HOLLY DOES NOT USE IT. THANK YOU. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GORSE NEAR TERM...NIERENBERG/ROBERTSON SHORT TERM...NIERENBERG LONG TERM...GORSE AVIATION...GORSE/NIERENBERG/ROBERTSON MARINE...GORSE/NIERENBERG/ROBERTSON TIDES/COASTAL FLOODING... EQUIPMENT...