AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 212 AM EDT THU MAY 12 2011 .SYNOPSIS... A RIDGE OF HIGH PRESSURE ACROSS THE REGION THIS EVENING WILL REMAIN THROUGH THURSDAY AND THEN WEAKEN AND MOVE EAST. LOW PRESSURE WILL ADVANCE FROM THE GREAT LAKES AND OHIO VALLEY AND ARRIVE OVER OUR AREA THIS WEEKEND. A FRONTAL SYSTEM AHEAD OF THE LOW WILL BRING SHOWERY WEATHER THIS WEEKEND AND INTO NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... NOT MUCH IN THE WAY OF CHANGE TO THE FORECAST FOR THE OVERNIGHT. IT LOOKS LIKE THE MAIN MASS OF LOW CLOUDS ASSOCIATED WITH THE SURFACE LOW WELL EAST OF THE COAST WILL BYPASS THE EASTERN AREAS TONIGHT. NEAR TERM GUIDANCE SHOWS SOME MOISTURE REMAINING TRAPPED UNDER THE INVERSION FOR AWHILE TONIGHT, THEREFORE THE CLOUD COVER WAS INCREASED A BIT FOR PARTS OF THE AREA. AS OF 02Z, AN AREA OF STRATOCUMULUS DEVELOPED AND EXPANDED SOME ACROSS PORTIONS OF EASTERN PENNSYLVANIA AS THE BOUNDARY LAYER CONTINUES TO COOL. THEREFORE, AT TIMES TONIGHT THE SKY COVER MAY BE VARIABLE ACROSS PARTS OF THE CWA. MOST OF THE CIRRUS FROM THE CONVECTION BACK OVER THE UPPER MIDWEST AND GREAT LAKES SHOULD THIN AS IT RIDGES THE MID LEVEL RIDGE POSITION, AND DROP SOUTHEAST ACROSS THE EASTERN OHIO VALLEY, WESTERN NEW YORK STATE AND PENNSYLVANIA. THIS SHOULD HAVE NO SIGNIFICANT EFFECT ON OUR SKY COVER TONIGHT. THE HOURLY GRIDS WERE ADJUSTED BASED ON THE 02Z OBSERVATIONS, AND THE LAV/LAMP GUIDANCE WAS BLENDED IN. NOT MUCH IN THE WAY OF CHANGES WERE MADE ATTM TO THE OVERNIGHT LOWS. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... THE WEATHER HAS BEEN GREAT THE PAST FEW DAYS...AND THURSDAY AND MOST OF FRIDAY SHOULD REMAIN THE SAME...BUT CHANGES TO A MORE UNSETTLED AND WET PATTERN WILL BEGIN DURING THE END OF THE SHORT TERM. THE HIGH THE HAS PROVIDED THE NICE WEATHER WILL DRIFT OVER THE AREA THURSDAY AND THEN WEAKEN WHILE PASSING OFF THE COAST FRIDAY. THIS WILL ALLOW LOW PRESSURE AND ITS ASSOCIATED FRONTS TO ADVANCE INTO THE ERN PART OF THE COUNTRY. WE WILL KEEP THE FCST DRY THROUGH FRIDAY BUT THEN THE OPERATIONAL MODELS AND THE MOS BEGIN TO INDICATE THAT SHOWERS WILL BE ARRIVING. A SLGT CHC FOR SHOWERS WAS KEPT IN FOR FRI NIGHT WITH A SMALL CHC FOR SHOWERS SAT. A FEW TSTMS MAY ARRIVE SAT AFTERNOON... SO I WILL LEAVE THOSE IN THERE FROM THE PREVIOUS FCST. TEMPERATURES WILL NOT BE EXCESSIVELY WARM WITH PREVAILING WINDS REMAINING FROM AN ONSHORE DIRECTION. HIGH TEMPERATURES THURSDAY WILL MOSTLY BE IN THE 70S...NEAR 70 ON FRIDAY AND MOSTLY IN THE 60S SATURDAY. READINGS NEAR THE SHORE WILL PROBABLY BE 5 TO 10 DEGREES COOLER. LOWS WILL MOSTLY BE IN THE 50S. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AN H5 TROF AND SEVERAL AREAS OF LOW PRESSURE WILL DOMINATE THE EXTENDED PD. SO EXPECT A CLOUDY AND UNSETTLED WX PATN. WHILE NO DAY WILL BE A COMPLETE WASH OUT, BUT THERE WILL BE PERIODS OF SHOWERS. MODELS DIFFER ON TIMING OF THE FEATURES THAT WILL MOVE THROUGH, AND THEREFORE ITS DIFFICULT TO PINPOINT THE RAINIEST PERIODS, BUT STILL IT DOESN`T LOOK TO BE THE NICEST WEEKEND AND CERTAINLY NOT AS NICE AS LAST WEEKEND. WENT AT OR SLIGHTLY BELOW GUID TEMPS THIS WEEKEND DUE TO CLOUD COVER AND RNFL POTENTIAL, BUT STILL TEMPS SHOULD BE AROUND NRML THRU THE PD. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. GFS/ECMWF COMBINATION WAS FAVORED FOR THE RH TSECTIONS WITH LESS CONSIDERATION GIVEN TO THE 00Z/12 NAM IN THIS FCST. THROUGH 12Z...VFR. PATCHY CIGS NEAR 6000 FT. LIGHT WIND. AFTER 12Z...VFR WITH AREAS OF CIGS NEAR 5000 FT DEVELOPING LATER THIS MORNING OR MIDDAY. LIGHT WIND BECOMING AFTERNOON SEA BREEZES ALONG ALL WATER LOCATIONS...IE WIND EVENTUALLY BECOMING SSE DURING THE AFTN. KPHL/KILG MAY HAVE MOSTLY SW WIND THRU 18Z BEFORE THE WIND BACKS TO S OR SSE? TONIGHT...VFR TO START. MVFR CONDS IN SC/FOG MAY DEVELOP VCNTY KABE AND KRDG NEAR OR AFTER 06Z. OUTLOOK... FRIDAY...VFR WITH CIGS DEVELOPING MIDDAY AOA 4000 FT. LIGHT S OR SSE WIND. WEEKEND...WIDESPREAD MVFR CIGS AND OCNLY IFR CONDS IN SHOWERS. ISOLATED TSTMS POSSIBLE SUNDAY. LOWEST CIGS/VSBY EXPECTED SAT NIGHT AND SUNDAY MORNING AHEAD OF THE WARM FRONT. E-SE WIND UNDER 20 KTS. MONDAY...CONDS MAY IMPROVE TO VFR CIGS DURING THE DAY THEN DETERIORATE AT NIGHT TO MVFR CONDS OR LOWER AS BRIEFLY WSW FLOW DURING THE DAY BACKS TO SLY AT NIGHT? CONFIDENCE LESS THAN AVG. TUESDAY...VARIABLE CIGS BUT TENDENCY FOR MVFR OR IFR DEVELOPING IN SHOWERS/ISO TSTMS. CONFIDENCE LESS THAN AVG. && .MARINE... HAZARDOUS SEAS SCA CONTINUES ON THE ATLC WATERS AND MAY EXTEND IN THE 330 AM FCST INTO MIDDAY FRIDAY. THE PROBLEM: 4 FT E SWELL AT 44025 AND 44065 WITH A 5-6 FT NE SWELL AT 44009 MAKING IT MORE LIKELY THAT THE DEL AND POSSIBLY FAR S NJ COASTAL ZONES WILL REMAIN IN THE HAZARDOUS SEAS ADVY REGION THRU MIDDAY FRIDAY. IT MAY NOT BE CORRECT TO EXTEND ADVY ANY FURTHER THAN IT IS NOW IN THE COASTAL ZONES N OF ACY. SOME MODEL GUIDANCE CONTS 44009 LINKED SCA HAZARDOUS SEAS 5 FT OR HIGHER INTO THE 16TH OF MAY WHILE 44025 IS MORE OF A MARGINAL 1 FT EITHER SIDE OF 5 FT FOR THE NEXT COUPLE OF DAYS. NO ADVISORY IS NEEDED FOR THE DELAWARE BAY AT THIS TIME AS WINDS ARE EXPECTED TO REMAIN BELOW CRITERIA LEVELS THROUGH SATURDAY MORNING. THIS WEEKEND...SE WINDS INCREASE LATE SATURDAY AND BECOME MORE SLY SOMETIME SUNDAY OCNL NEAR 20 KNOTS. MONDAY...VARIABLE MAINLY S WINDS. TUESDAY...ANOTHER PULSE OF SE FLOW TO 20 KTS POSSIBLE. && .TIDES/COASTAL FLOODING... SO FAR THE ONLY MINOR INUNDATION TIDAL FLOODING THAT OCCURRED AT MONDAY IN OUR AREA OF RESPONSIBILITY WAS CAMBRIDGE MD...3/4 OF AN INCH ABV FS AT 1030AM WEDNESDAY. MANY MORE OPPORTUNITIES FOR MINOR CF THE NEXT 5 DAYS WITH BEST CHC FOR EXTENSIVE ADVY THRESHOLD EXCEEDENCE SUNDAY AND NEXT TUESDAY- WEDNESDAY. IN THE MEANTIME...POCKETS OF MARGINAL MINOR MIGHT OCCUR THIS COMING NIGHT IN UPPER DEL BAY AND CHES BAY BUT NO STMT AT THIS TIME DUE TO MARGINALITY. FULL MOON THIS COMING TUESDAY THE 17TH SO ASTRO TIDES ARE INCREASING DAILY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM EDT FRIDAY FOR ANZ450>455. && $$ SYNOPSIS...O`HARA