000 FXUS61 KPHI 250902 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 402 AM EST WED NOV 25 2009 .SYNOPSIS... A WEAK RIDGE OF HIGH PRESSURE WILL DIMINISH THIS MORNING. LOW PRESSURE OFF THE EAST COAST AND ANOTHER LOW MOVING ACROSS THE UPPER GREAT LAKES REGION WILL EVENTUALLY COMBINE ACROSS NEW ENGLAND ON FRIDAY. A STRONG COLD FRONT WILL CROSS THE AREA FRIDAY MORNING. HIGH PRESSURE WILL BUILD IN OVER THE WEEKEND AND REMAIN FOR MONDAY. ANOTHER WEATHER DISTURBANCE WILL APPROACH THE AREA NEXT MONDAY NIGHT. && .NEAR TERM /THROUGH TODAY/... PLENTY OF LOW LEVEL MOISTURE HAS RETURNED TO THE AREA. LOW CLOUDS AND SOME DRIZZLE ARE OCCURRING AT THE OBS SITES EARLY TODAY. A VORT MAX IS SHOWN BY THE GFS APPROACHING FROM THE WEST TODAY AND CROSSING THE AREA EARLY THIS EVENING. THIS VORT MAX AND THE LOW LEVEL MOISTURE WILL COMBINE TO PRODUCE SCATTERED SHOWERS ACROSS MUCH OF THE AREA TODAY. I HAVE USED A 40 POP FOR THE FCST FOR TODAY SINCE THIS IS OFFERED IN THE 6HR MAV GUIDANCE. THE NAM/MET GUIDANCE WAS REJECTED DUE TO ITS OVER-PRODUCTION OF RAIN IN THE FIRST FCST PERIOD...WHICH DOESN'T APPEAR TO BE VERIFYING. HIGH TEMPERATURES TODAY WILL RANGE FROM THE LOW 50S NORTH TO UPPER 50S ACROSS THE DELMARVA. && .SHORT TERM /TONIGHT THROUGH FRIDAY/... A BIT OF A LULL TONIGHT AND THE FIRST PART OF THURSDAY AS WE WILL BE BETWEEN THE FIRST DISTURBANCE AND THE STRONGER ONE EXPECTED TO MOVE IN FROM THE WEST LATER THURSDAY. A WEAK HIGH PRESSURE AND RIDGING ALOFT SHOULD ACT TO REDUCE THE COVERAGE OF SHOWERS TONIGHT FROM SOUTH TO NORTH...AND LITTLE IF ANY SHOWERS ARE EXPECTED EARLY THURSDAY. CLOUDS WILL STILL BE ABUNDANT ACROSS THE AREA HOWEVER. SHOWERS WILL INCREASE FROM THE WEST LATER THURSDAY... FOLLOWED BY POPS RISING TO LIKELY LEVELS THURSDAY NIGHT AND FRIDAY MORNING AS THE STRONG COLD FRONT CROSSES THE AREA. THE DEEPENING UPPER LOW AND COLD AIR WITH IT MAY CONTRIBUTE TO SOME ISOLATED CONVECTION LATE THU NIGHT OF FRI MORNING. NO MENTION OF IT WAS PLACED IN THE GRIDS AT THIS POINT. WINDY CONDITIONS AND SEASONABLY COOL AIR WILL BE ACROSS THE AREA FRIDAY WITH THE LIKELY SHOWERS DURING THE MORNING BECOMING SCT BY AFTERNOON. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE STRONG LOW PRESSURE SYSTEM WILL MOVE FURTHER NE TOWARD THE CANADIAN MARITIMES FRIDAY NIGH AS HIGH PRESSURE BUILD IN FROM THE W. FRIDAY NIGHT INTO EARLY SATURDAY COULD BE QUITE BREEZY DUE TO THE PRESSURE GRADIENT BETWEEN THE TWO SYSTEMS. THERE COULD ALSO BE SOME LINGERING SHOWERS EARLY IN THE DAY, BUT CONDS WILL IMPROVE AS THE HIGH MOVES IN. MOST OF SATURDAY AND ALL DAY SUNDAY LOOK DRY, WITH TEMPS AROUND NORMAL. THE HIGH BUILDS IN FURTHER ON MONDAY, SO DRY WX SHOULD CONTINUE. BY TUESDAY, LOW PRESSURE AND A CDFNT IS EXPECTED TO APPROACH THE REGION FROM THE S AND W. THERE ARE STILL SOME MDL DIFFS WITH THE HANDLING OF THESE FEATURES. THE GFS HAS A MUCH STRONGER LOW EJECTING OUT OF THE SERN CONUS AND MOVG TWD THE APPALACHIANS. THE ECMWF IS FURTHER E AND WEAKER. SO, WHILE THERE IS DISAGREEMENT ON THE FEATURES THEMSELVES, THE MDLS AGREE THAT TUESDAY LOOKS WET. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY IS A BIG TRAVEL DAY FOR THANKSGIVING. HOWEVER, IT NOW APPEARS AS THOUGH IFR CONDITIONS WILL DOMINATE TODAY AND COULD HAVE AN IMPACT ON THE HOLIDAY TRAVEL AND COULD CAUSE AIRPORT DELAYS. CURRENT TRENDS ARE TO IFR CONDITIONS. LOW CLOUDS FROM THE SOUTH AND SOUTHEAST WERE STREAMING INTO THE REGION. ALTHOUGH SOME SITES WERE STILL MVFR/VFR...BY 08Z ALL TAF SITES SHOULD SEE IFR CIGS. VSBYS WERE 5 MI OR MORE, BUT BY SUNRISE, THE VSBYS SHOULD ALSO DETERIORATE AS SOME LIGHT RAIN AND DRIZZLE DEVELOP AND VSBY SHOULD DROP TO 3-4 MI WITH SOME AREAS DROPPING TO 1-2 MI. THE IFR CONDITIONS ARE THEN FORECAST TO CONTINUE THROUGH THE AFTN WITH CIGS THE MAIN CULPRIT FOR IFR. HOWEVER, THE LIGHT RAIN AND DRIZZLE SHOULD DISSIPATE BY LATE AFTN. AFTER DARK, THE CLOUDS MAY BREAK AT SOME LOCATIONS, BUT IF THEY DO, IFR OR LIFR CIG/VSBY COULD DEVELOP WITH AREAS OF FOG. ON THURSDAY...COLD ADVECTION IS FORECAST TO DEVELOP AND CIGS/VSBYS SHOULD IMPROVE TO VFR DURING THE MORNING. OUTLOOK... A COLD FRONT MOVES THROUGH FROM THE NW THURSDAY NIGHT. BRISK NW WINDS SHOULD DEVELOP BEHIND THE FRONT. ALSO, SHOWERS ARE EXPECTED ON FRIDAY WITH MVFR AND POSSIBLY IFR CONDITIONS IN THE SHOWERS. THERE MAY ALSO BE SOME SNOW MIXED WITH RAIN SHOWERS MAINLY N/W OF PHL. OVER THE WEEKEND...CONDITIONS SHOULD BE VFR. && .MARINE... ONSHORE WINDS OF 10 TO 15 KT WILL CONTINUE TODAY, BUT SEAS SHOULD REMAIN ABOVE 5 FT ON THE OCEAN. THEREFORE THE SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT ON THE OCEAN. A TEMPORARY WIND SHIFT TO WEST OR NW SHOULD OCCUR TONIGHT BEFORE WINDS ONCE AGAIN BECOME NE ON THURSDAY. HOWEVER, WINDS SHOULD STILL BE RELATIVELY LIGHT. A COLD FRONT FINALLY MOVES THROUGH THE AREA FROM THE NW THURSDAY NIGHT. THIS WILL ALLOW FOR A SHIFT TO NW THAT WILL LAST THROUGH THE WEEKEND. ON FRIDAY, THE WINDS WILL INCREASE TO 25 KT AT LEAST IN GUSTS AS WE GET COLDER AIR ON THE WARMER WATERS. FRIDAY NIGHT INTO SATURDAY STRONGER WINDS ARE EXPECTED AND WE COULD SEE THE WINDS REACH GALE FORCE ON BOTH THE OCEAN AND DELAWARE BAY. HIGH PRESSURE IS FORECAST TO MOVE BY TO THE SOUTH OVER THE WEEKEND. THIS WILL MEAN WINDS SHOULD DECREASE A BIT SATURDAY NIGHT AND EVEN MORE ON SUNDAY. ON SUNDAY, WINDS MAY EVEN DROP BELOW 25 KT. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ450>455. && $$ SYNOPSIS...O'HARA NEAR TERM...O'HARA SHORT TERM...O'HARA LONG TERM...NIERENBERG AVIATION...STAUBER MARINE...STAUBER