Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 231803 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 103 PM EST TUE DEC 23 2014 .SYNOPSIS... A WEAK AREA OF LOW PRESSURE WILL CONTINUE TO LIFT NORTHWARD ALONG THE COAST EAST OF THE AREA TODAY, WHILE A FRONTAL BOUNDARY WILL EXTEND SOUTHWARD INTO THE CAROLINA. ANOTHER LOW DEVELOPING ACROSS THE DEEP SOUTH TODAY WILL LIFT NORTHWARD TONIGHT AND INTO THE GREAT LAKES REGION WEDNESDAY INTO WEDNESDAY NIGHT. THE COASTAL FRONT WILL BEGIN LIFTING NORTHWARD AS A WARM FRONT AND CROSS INTO THE AREA WEDNESDAY, FOLLOWED BY A COLD FRONT WEDNESDAY NIGHT INTO THURSDAY MORNING. HIGH PRESSURE WILL BUILD IN FROM THE SOUTH THURSDAY NIGHT INTO FRIDAY NIGHT, BEFORE PUSHING BACK SOUTHWARD SATURDAY. AN AREA OF LOW PRESSURE WILL MOVE INTO EASTERN CANADA THROUGH SATURDAY NIGHT, PULLING A COLD FRONT ACROSS THE AREA BY SUNDAY MORNING. HIGH PRESSURE WILL BUILD ACROSS NEW ENGLAND INTO EARLY NEXT WEEK, WHILE A LOW PRESSURE MAY PASS JUST TO OUR SOUTH SUNDAY NIGHT INTO MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 930 AM UPDATE...NOT MANY CHANGES IN THE NEAR TERM AS THE FORECAST IS ON TRACK. THERE IS CURRENTLY A BIT OF A LULL IN THE PRECIP WHICH WILL LIKELY CONTINUE THROUGH AT LEAST EARLY AFTERNOON. PREVIOUS NEAR TERM DISCUSSION...THE MID LEVEL PATTERN FOR TODAY FEATURES A TROUGH OVER THE MIDDLE PART OF THE COUNTRY AND A RIDGE OVER THE WESTERN NORTH ATLANTIC. WEAK IMPULSES ARE FORECAST TO PASS OVERHEAD IN THE SOUTHWEST FLOW AND THEY WILL HELP TO TRIGGER SOME LIGHT RAIN AT TIMES. THE SURFACE HIGH CENTERED OVER ATLANTIC CANADA WILL CONTINUE TO RECEDE TODAY GRADUALLY LOSING ITS INFLUENCE OVER OUR REGION. WEAK SURFACE LOW PRESSURE LOCATED OFF THE MARYLAND COAST AROUND 630 AM IS EXPECTED TO DRIFT NORTHWARD TO A LOCATION OFF THE CENTRAL PART OF THE NEW JERSEY COAST TOWARD EVENING. THE LOW LEVELS OF THE ATMOSPHERE SHOULD CONTINUE TO MOISTEN TODAY WITH WARM ADVECTION ALOFT. AS A RESULT, THE SKY IS FORECAST TO REMAIN OVERCAST AND WE WILL SEE PATCHY DRIZZLE ALONG WITH THE AREAS OF LIGHT RAIN. SOME FOG IS LIKELY IN THE ELEVATED TERRAIN. THE LIGHT EAST NORTHEAST WIND THIS MORNING SHOULD BECOME VARIABLE FOR THIS AFTERNOON AS THE CENTER OF THE LOW ARRIVES. TEMPERATURES ARE EXPECTED TO RISE ONLY A FEW DEGREES WITH HIGHS IN THE 40S TO THE NORTHWEST OF THE FALL LINE AND MAINLY IN THE LOWER AND MIDDLE 50S ON THE COASTAL PLAIN. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... LITTLE CHANGE IN THE OVERALL PATTERN IS EXPECTED FOR TONIGHT. THE WEAK LOW OFF OUR COAST SHOULD DISSIPATE. WE ARE ANTICIPATING AN OVERCAST SKY WITH SOME RAIN AND DRIZZLE. CEILINGS SHOULD LOWER OVERNIGHT AND WE WILL LIKELY SEE AREAS OF FOG THROUGHOUT OUR REGION. TEMPERATURES WILL CHANGE LITTLE DURING THE NIGHT AND THEY MAY ACTUALLY BEGIN TO RISE A BIT TOWARD WEDNESDAY MORNING. A WARM FRONT IS FORECAST TO LIFT TOWARD OUR REGION LATE TONIGHT AND IT SHOULD REACH SOUTHERN DELAWARE AND THE ADJACENT COUNTIES OF MARYLAND TOWARD DAYBREAK. RAINFALL RATES ARE EXPECTED TO INCREASE LATE TONIGHT IN THE ISENTROPIC LIFT. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... A WET START TO THE LONG TERM FORECAST, FOLLOWED BY A DRYING OUT PERIOD FOR THE END OF THE WEEK, THEN SNOW POTENTIAL FOR THE END OF THE WEEKEND? THE LONG TERM STARTS OFF WITH AN EXTENDED PERIOD OF WET WEATHER WEDNESDAY INTO WEDNESDAY NIGHT. AN AREA OF LOW PRESSURE DEVELOPING ACROSS THE DEEP SOUTH TODAY WILL LIFT INTO THE GREAT LAKES WEDNESDAY INTO WEDNESDAY NIGHT. WHILE DOING SO, A FRONTAL BOUNDARY ALONG THE EAST COAST THAT EXTENDS TO OUR SOUTH WILL LIFT INTO THE AREA DURING THE DAY WEDNESDAY. AMPLE LOW/MID LEVEL MOISTURE AND LIFT WILL MOVE ACROSS THE AREA THROUGH THE DAY INTO THE NIGHT AND LEAD TO PERIODS OF RAIN. NOT OVERLY EXCITED ABOUT THUNDERSTORM POTENTIAL, BUT K-INDEX VALUES ARE IN THE LOW 30S AND TOTAL TOTALS APPROACH 44/45, SO WOULD NOT BE TOO SURPRISED IF A FEW ISOLATED LIGHTNING STRIKES OCCUR IN THE WARM SECTOR AS THE WARM FRONT LIFTS THROUGH THE AREA; SO WE`VE EXPANDED THE ISOLATED THUNDER. THE COLD FRONT APPROACHES FROM THE WEST DURING THE NIGHT WEDNESDAY, AND SHOULD PUSH THROUGH BY THURSDAY MORNING. THERE REMAINS PLENTY OF MOISTURE/LIFT ACROSS THE AREA SO PERIODS OF RAIN WILL CONTINUE THROUGH THE NIGHT. THINK ANY THUNDER POTENTIAL SHOULD PUSH EASTWARD DURING THE EVENING AS THE FRONT APPROACHES, SO SHIFTED ISOLATED THUNDER ACROSS THE EASTERN HALF DURING THE EVENING. ALL PRECIPITATION WILL FALL AS RAIN WEDNESDAY INTO WEDNESDAY NIGHT, AND AMOUNTS ARE EXPECTED TO BE AROUND A HALF INCH TO AN INCH, WITH SOME HIGHER AMOUNTS OF ONE AND A HALF INCHES POSSIBLE WEDNESDAY INTO WEDNESDAY NIGHT. EVEN WITH THE HIGHER END OF THE EXPECTED RAINFALL, IT SHOULD NOT CAUSE ANY FLOODING PROBLEMS, SO NO HEADLINES ANTICIPATED. THE FRONT WILL CONTINUE TO OUR EAST DURING THE DAY THURSDAY. SOME SHOWERS ARE POSSIBLE EARLY IN THE MORNING AS THE FRONT PULLS OUT. HOWEVER, THE MAIN CONCERN WITH THURSDAY WILL BE THE WINDS. SOUNDINGS SHOW THE BEST POTENTIAL FOR WINDS TO BE AROUND 30-35 MPH, BUT IF FULL MIXING OCCURRED, THERE COULD BE SOME GUSTS IN THE LOW 40S. HOWEVER, STILL LOOKS TO BE BELOW ADVISORY LEVELS. THERE IS SOME MOISTURE THAT SLIDES TO OUR NORTH DURING THE DAY ALONG WITH A SHORT WAVE/VORT MAX, BUT LOW LEVEL LIFT IS LACKING. IT IS POSSIBLE THAT SOME LAKE EFFECT SHOWERS WILL OCCUR TO OUR NORTH AND WEST, BUT NOT CONFIDENT ON THEM REACHING OUR AREA, SO WILL LEAVE THEM OUT FOR NOW. A DRYING OUT PERIOD IS EXPECTED THURSDAY NIGHT INTO SATURDAY AS HIGH PRESSURE BUILDS IN FROM THE SOUTH THURSDAY NIGHT INTO FRIDAY NIGHT, THEN PUSHES BACK SOUTHWARD SATURDAY. A COLD FRONT IS EXPECTED TO MOVE INTO THE AREA SATURDAY NIGHT INTO SUNDAY, ALTHOUGH THERE IS SOME TIMING AND STRENGTH DIFFERENCES WITH THE GFS AND ECMWF. THE GFS IS FASTER AND DRIER, WHILE THE ECMWF AS WETTER AND SLOWER. WITH THE UNCERTAINTY, WILL STILL NOT HIT THE PRECIPITATION CHANCES HARD AND KEEP SLIGHT CHANCE TO CHANCE SATURDAY NIGHT INTO SUNDAY. BOTH MODELS DEVELOP AN AREA OF LOW PRESSURE ALONG THE FRONT AFTER IT SAGS SOUTH OF THE AREA INTO MONDAY, ALTHOUGH THERE CONTINUES TO BE TIMING DIFFERENCES. THE GFS IS FURTHER SOUTH, WHILE THE ECMWF IS FARTHER NORTH. WITH THE CONTINUING UNCERTAINTY, WILL ONLY KEEP SLIGHT CHANCE TO CHANCE INTO SUNDAY NIGHT MONDAY. THE THING TO NOTE IS WITH HIGH PRESSURE BUILDING TO THE NORTH, THERE COULD BE ENOUGH COLD AIR THAT IF ANY PRECIPITATION DOES OCCUR THAT IT COULD BE MORE SNOW THAN NOT. STILL A WAYS OUT, SO WE`LL SEE HOW IT PROGRESSES IN THE DAYS TO COME. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. IT WILL BE A CHALLENGING DAY AND NIGHT FOR AVIATION INTERESTS, AS IFR CONDITIONS ARE ANTICIPATED TO CONTINUE THROUGH THE TAF PERIOD. WINDS SHOULD BECOME LIGHT AND VARIABLE OVER THE NEXT FEW HOURS. A LIGHT EAST WIND MAY DEVELOP LATE TONIGHT. OUTLOOK... WEDNESDAY-WEDNESDAY NIGHT...SIGNIFICANTLY REDUCED CONDITIONS, MOST LIKELY IFR/LIFR, WITH PERIODS OF RAIN, SOME HEAVY AT TIME. SOME IMPROVEMENT POSSIBLE VERY LATE WEDNESDAY NIGHT. THURSDAY...CONDITIONS IMPROVING TO VFR DURING THE MORNING. WEST WINDS INCREASING AND GUSTY AT LEAST 25-30 KNOTS. THURSDAY NIGHT-SATURDAY...MAINLY VFR. GUSTY SOUTHWEST WINDS 15-20 KNOTS SATURDAY. && .MARINE... THE PRESSURE GRADIENT BETWEEN THE WEAK LOW OFF THE MIDDLE ATLANTIC COAST AND THE HIGH OVER EASTERN CANADA WAS MAINTAINING A STEADY EAST NORTHEAST WIND ALONG OUR STRETCH OF THE COAST. WAVE HEIGHTS ON OUR OCEAN WATERS RESPONDED AND THEY WERE IN THE 4 TO 7 FOOT RANGE AROUND 630 AM. WAVES ARE FORECAST TO REMAIN IN THAT RANGE INTO THIS MORNING AS THE LOW MOVES NORTHWARD AND OVER OUR COASTAL WATERS. A VERY SLOW DECREASE IN WAVE HEIGHTS IS EXPECTED FROM THIS AFTERNOON INTO TONIGHT AS THE LOW DISSIPATES SLOWLY. WE HAVE A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS. IT IS IN EFFECT FOR OUR OCEAN WATERS OFF DELAWARE AND OFF THE MOUTH OF DELAWARE BAY UNTIL 600 PM. THE ADVISORY GOES UNTIL 200 AM WEDNESDAY FOR OUR OCEAN WATERS OFF NEW JERSEY. WIND SPEEDS ARE EXPECTED TO DECREASE AND THEY SHOULD BE 10 KNOTS OR LESS FROM LATE THIS MORNING INTO TONIGHT. OUTLOOK... WEDNESDAY-WEDNESDAY NIGHT...WINDS AND SEAS EXPECTED INCREASE TO SMALL CRAFT ADVISORY LEVELS DURING THE DAY AND CONTINUE INTO THE NIGHT. THURSDAY...SMALL CRAFT ADVISORY LEVELS REMAIN BEHIND A COLD FRONTAL PASSAGE, WITH NEAR GALE FORCE WINDS POSSIBLE. THURSDAY NIGHT...CONDITIONS WILL RETURN BELOW ADVISORY LEVELS OVERNIGHT THURSDAY. FRIDAY-SATURDAY...SUB-SMALL CRAFT ADVISORY LEVELS, ALTHOUGH WINDS MAY GUST NEAR 20 KNOTS ON SATURDAY. && .TIDES/COASTAL FLOODING... ALL TIDAL GAUGES SHOW CONDITIONS BELOW MINOR FLOODING THRESHOLDS. THEREFORE, THE COASTAL FLOOD ADVISORY HAS BEEN CANCELLED. WITH THE DECREASE IN THE ON SHORE FLOW, DO NOT ANTICIPATE ANY COASTAL FLOODING ISSUES WITH THE NEXT FEW HIGH TIDE CYCLES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 AM EST WEDNESDAY FOR ANZ450>453. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM EST THIS EVENING FOR ANZ454-455. && $$ SYNOPSIS...ROBERTSON NEAR TERM...IOVINO/JOHNSON SHORT TERM...IOVINO LONG TERM...ROBERTSON AVIATION...IOVINO/ROBERTSON MARINE...IOVINO/ROBERTSON TIDES/COASTAL FLOODING...

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