Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 200855 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 355 AM EST SAT DEC 20 2014 .SYNOPSIS...
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HIGH PRESSURE CENTERED OVER SOUTHWESTERN QUEBEC THIS MORNING WILL DRIFT EASTWARD AND IT SHOULD REACH ATLANTIC CANADA ON MONDAY. WEAK LOW PRESSURE IS FORECAST TO DEVELOP OFF THE CAROLINA COAST ON MONDAY BEFORE MOVING SLOWLY NORTHEASTWARD AND DISSIPATING. STRONG LOW PRESSURE IS EXPECTED TO LIFT NORTHWARD FROM THE LOWER MISSISSIPPI RIVER VALLEY AND ACROSS THE GREAT LAKES DURING THE MID WEEK PERIOD. THE LOW IS ANTICIPATED TO PULL A WARM FRONT THROUGH OUR REGION ON WEDNESDAY, FOLLOWED BY A COLD FRONT ON WEDNESDAY NIGHT. HIGH PRESSURE IS EXPECTED TO FOLLOW FROM THE SOUTHWEST FOR THURSDAY AND FRIDAY. ANOTHER COLD FRONT IS FORECAST TO APPROACH FROM THE WEST AND IT MAY ARRIVE ON SATURDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS EASTERN CANADA AND NORTHERN NEW ENGLAND TODAY, WITH THE MID-ATLANTIC BEING ON THE SOUTHERN FRINGE. THIS WILL KEEP A DRY, LIGHT NORTHERLY FLOW ACROSS THE AREA. WITH PW VALUES BETWEEN ONE-QUARTER AND ONE-THIRD OF AN INCH, NO PRECIPITATION IS FORECAST. HOWEVER, THERE WILL REMAIN MOISTURE CAUGHT UP UNDERNEATH THE INVERSION WHICH SHOULD KEEP SOME CLOUD COVER ACROSS THE AREA. EVEN IF THE LOWER LEVEL CLOUDS SCATTER OUT DURING THE DAY, WE SHOULD SEE AN INCREASE IN HIGH LEVEL CLOUDS AS A SHORT WAVE/VORTICITY MAX SLIDES ACROSS THE AREA. THE NORTHERLY WIND, ALONG WITH ANY CLOUD COVER SHOULD PREVENT TEMPERATURES FROM WARMING SIGNIFICANTLY TODAY, SO WE USED A BLEND OF MAV/MET MOS AND MOSGUIDE WHICH WERE IN PRETTY GOOD AGREEMENT.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
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NOT MUCH OF A CHANGE TO THE FORECAST TONIGHT FROM THE DAY TIME. HIGH PRESSURE, CENTERED ACROSS NORTHERN NEW ENGLAND AND EASTERN CANADA REMAINS IN CONTROL OF THE WEATHER. WITH CONTINUING LOW PW VALUES, NO PRECIPITATION IS EXPECTED. CLOUD COVER SHOULD REMAIN ACROSS THE AREA, ESPECIALLY AS A SHORT WAVE/VORTICITY MAX SLIDES TOWARD THE AREA OVERNIGHT. OVERNIGHT LOWS WERE A BLEND OF MAV/MET MOS AND MOSGUIDE WHICH WERE IN PRETTY GOOD AGREEMENT.
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&& .LONG TERM /SUNDAY THROUGH FRIDAY/...
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A MID LEVEL SHORT WAVE THAT WAS LOCATED OVER WESTERN IOWA AND VICINITY EARLY THIS MORNING WILL PROGRESS EASTWARD AND IT SHOULD PASS OVER OUR REGION EARLY ON SUNDAY MORNING. WHILE WE ARE ANTICIPATING SOME CLOUDS WITH THE SYSTEM THERE SHOULD NOT BE ENOUGH MOISTURE TO PRODUCE ANY PRECIPITATION. SURFACE HIGH PRESSURE IS FORECAST TO BE LOCATED OVER SOUTHERN QUEBEC ON SUNDAY MORNING. THE CENTER OF THE HIGH SHOULD DRIFT EASTWARD REACHING ATLANTIC CANADA ON MONDAY AND MONDAY NIGHT. A RIDGE AXIS IS EXPECTED TO NOSE SOUTHWESTWARD ALONG THE LEE OF THE APPALACHIANS AT THAT TIME WITH AN INVERTED TROUGH DEVELOPING OFF THE COAST. WEAK LOW PRESSURE IS ANTICIPATED TO DEVELOP ON THE TROUGH OFF THE CAROLINA COAST ON MONDAY. THE FEATURE IS FORECAST TO REMAIN WEAK AS IT DRIFTS NORTHEASTWARD REACHING THE WATERS OFF THE DELMARVA BEFORE DISSIPATING ON TUESDAY. AREAS OF LIGHT PRECIPITATION ARE EXPECTED TO SPREAD SLOWLY NORTHWARD INTO OUR REGION ON MONDAY AND THEY SHOULD REMAIN HERE FOR MONDAY NIGHT AND TUESDAY. THE OVERALL TREND WILL BE TOWARD WARMING TEMPERATURES. AS A RESULT, MOST OF THE PRECIPITATION IS ANTICIPATED TO BE IN THE FORM OF RAIN. HOWEVER, POCKETS OF BELOW FREEZING TEMPERATURES MAY LINGER IN THE POCONOS ON MONDAY NIGHT INTO EARLY TUESDAY MORNING SO WE HAVE MENTIONED A CHANCE OF FREEZING RAIN THERE. OUR MAIN WEATHER FEATURE FOR THE COMING WEEK IS THE DEEP MID LEVEL TROUGH THAT IS FORECAST TO DIG OVER THE MIDDLE PART OF THE COUNTRY ON MONDAY AND TUESDAY. THE TROUGH IS EXPECTED TO LIFT NORTHEASTWARD AND ITS AXIS SHOULD PASS OVERHEAD EARLY ON THURSDAY. SURFACE LOW PRESSURE IS ANTICIPATED TO DEVELOP OVER THE LOWER MISSISSIPPI RIVER VALLEY ON TUESDAY IN RESPONSE TO THE TROUGH. THE LOW IS FORECAST TO STRENGTHEN AS IT MOVES ACROSS THE GREAT LAKES ON WEDNESDAY AND WEDNESDAY NIGHT. THE SYSTEM SHOULD HAVE AN OPPORTUNITY TO TAP INTO GULF MOISTURE AND IT WILL BRING THE POTENTIAL FOR SOME MODERATE TO HEAVY RAINFALL TO OUR REGION FROM WEDNESDAY INTO EARLY WEDNESDAY NIGHT. THE LOW IS EXPECTED TO PULL A WARM FRONT THROUGH OUR REGION ON WEDNESDAY WITH TEMPERATURES FORECAST TO RISE INTO THE 50S AT MOST LOCATIONS. SOME 60 DEGREE READINGS ARE POSSIBLE ON THE DELMARVA AND PERHAPS IN FAR SOUTHERN NEW JERSEY. CONDITIONS MAY BECOME QUITE BREEZY IN THE WARM SECTOR WHERE THE ATMOSPHERE SHOULD MIX RATHER EFFICIENTLY. A STRONG COLD FRONT IS FORECAST TO FOLLOW ON WEDNESDAY NIGHT WITH TEMPERATURES DROPPING BACK INTO THE 30S BY DAYBREAK ON THURSDAY. THE PROBABILITY OF PRECIPITATION DECREASES RAPIDLY ON WEDNESDAY NIGHT AS DRY AIR IS EXPECTED TO BUILD INTO OUR REGION FROM THE SOUTHWEST. RIDGING IS FORECAST TO DEVELOP AT THE SURFACE AND ALOFT FOR THURSDAY INTO FRIDAY WITH MAINLY DRY WEATHER AND SEASONABLE TEMPERATURES ANTICIPATED. A MID LEVEL SHORT WAVE MAY APPROACH FROM THE WEST ON SATURDAY ALONG WITH AN ASSOCIATED SURFACE COLD FRONT. THE GUIDANCE DIFFERS A BIT ON THE TIMING OF THE FEATURE AT THIS POINT AS WELL ON THE AMOUNT OF MOISTURE ASSOCIATED WITH THE SYSTEM.
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&& .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
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THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. MOST OF THE TAF SITES ARE NOW MVFR, EXCEPT PHL/ILG/MIV, ALTHOUGH THEY SHOULD BE THERE SHORTLY. THE MVFR CIGS WILL CONTINUE ACROSS THE TAF SITES THROUGH THIS MORNING AS MOISTURE REMAINS TRAPPED UNDERNEATH THE INVERSION. CLOUDS MAY SCATTER OUT DURING THE DAY WITH HIGHER LEVEL CLOUDS OVERHEAD, LEADING TO VFR CONDITIONS FOR THE REMAINDER OF THE PERIOD. IF THE CLOUDS DO NOT BEGIN TO SCATTER OUT BY MIDDAY, IT`S POSSIBLE WE COULD SEE AN EXTENDED PERIOD OF MVFR CIGS THROUGH THE DAY INTO TONIGHT. NORTHERLY WINDS WILL BE LIGHT, GENERALLY AROUND 5-10 KNOTS OR LESS THROUGH THE DAY. SOME NORTHWEST TO WEST WINDS ARE POSSIBLE EARLY, BUT SHOULD BECOME MORE NORTHERLY DURING THE DAY. EVERYONE IS EXPECTED TO BECOME LIGHT AND VARIABLE/CALM LATER THIS AFTERNOON INTO THE EVENING/OVERNIGHT. OUTLOOK... SUNDAY AND SUNDAY NIGHT...MAINLY VFR. MONDAY...MAINLY VFR WITH A CHANCE OF LIGHT RAIN SPREADING NORTHWARD INTO OUR REGION. MONDAY NIGHT AND TUESDAY...CONDITIONS POSSIBLY LOWERING INTO THE MVFR CATEGORY WITH A CHANCE OF LIGHT RAIN. TUESDAY NIGHT...MVFR AND IFR CONDITIONS ANTICIPATED WITH RAIN LIKELY. WEDNESDAY...MVFR AND IFR CONDITIONS WITH RAIN LIKELY. THE RAIN MAY BE HEAVY AT TIMES. A GUSTY SOUTH WIND MAY DEVELOP, ESPECIALLY IN THE AFTERNOON.
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&& .MARINE...
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SUB-SMALL CRAFT ADVISORY CONDITIONS WILL REMAIN TODAY INTO TONIGHT AS HIGH PRESSURE FROM THE NORTH WILL AFFECT THE WATERS. OUTLOOK... SUNDAY THROUGH MONDAY NIGHT...NO MARINE HEADLINES ARE ANTICIPATED. TUESDAY AND TUESDAY NIGHT...WAVE HEIGHTS ON OUR OCEAN WATERS MAY BUILD TO 5 TO 6 FEET IN A DEVELOPING ONSHORE FLOW. WEDNESDAY...SOUTHERLY WIND GUSTS IN EXCESS OF 25 KNOTS ARE EXPECTED. WAVE HEIGHTS ON OUR OCEAN WATERS MAY BUILD TO 6 TO 9 FEET IN A STRONG SOUTHERLY FLOW.
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&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...IOVINO NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...IOVINO AVIATION...IOVINO/ROBERTSON MARINE...IOVINO/ROBERTSON

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