Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 061451 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 951 AM EST FRI MAR 6 2015 .SYNOPSIS... AN ARCTIC HIGH PRESSURE SYSTEM WILL MOVE ACROSS THE FORECAST AREA TODAY AND THEN SINK SOUTH ON SATURDAY. A WEAK LOW PRESSURE SYSTEM WILL TRACK TO OUR NORTH LATE SATURDAY INTO SUNDAY. A WEAK COLD FRONT SHOULD PASS ACROSS OUR REGION MONDAY. A LOW PRESSURE SYSTEM IS PREDICTED TO FORM ON THIS FRONTAL BOUNDARY OFF THE NORTH CAROLINA COAST TUESDAY AND THEN MOVE FARTHER OFFSHORE. A HIGH PRESSURE SYSTEM SHOULD THEN BUILD INTO THE EASTERN UNITED STATES ON WEDNESDAY AND THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 9:30 AM UPDATE: NOT MANY CHANGES, FORECAST STILL ON TRACK. CHANGES MAINLY INVOLVED A SLIGHT INCREASE IN SKY COVER FOR THE AFTERNOON AND SLIGHT TEMPERATURE ADJUSTMENTS BASED ON THE 14Z METARS. FAIR WEATHER AND COLD TEMPERATURES TODAY WITH HIGH PRESSURE BUILDING IN FROM THE OHIO VALLEY. SKIES WILL BE CLR THIS MORNING...AND THEN THERE WILL BE SOME HIGH CLOUDS THIS AFTERNOON. HIGH TEMPERATURES TODAY WILL BE WELL BELOW NORMAL...WITH LOW/MID 20S NORTH AND MID 20S TO LOW 30S OVER METRO PHILADELPHIA AND OVER THE DELMARVA. WINDS WILL BE NORTH OR NORTHWEST AT 5 TO 10 MPH THIS MORNING AND THEN BECOME WEST OR SOUTHWEST AROUND 5 MPH BY DUSK. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... SHORT TERM... HIGH PRESSURE WILL CONTINUE TO REMAIN OVER THE AREA TONIGHT. WINDS WILL BE LIGHTER THAN THU NIGHT AND WITH THE AMPLE SNOW COVER ACROSS THE REGION...LOW TEMPERATURES COULD BE AS COLD (OR PERHAPS COLDER) THAN THU NIGHTS READINGS. PRESENTLY WE HAVE SINGLE DIGITS ACROSS MOST AREAS WITH TEENS ALONG THE SHORE AND 12 FOR PHL. WINDS WILL BE LIGHT TONIGHT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... THE 500MB INITIALIZATION LOOKED BETTER OFF THE WRF VS THE GFS, OVERALL THEY WERE SPLIT AT 850MB AND BOTH ABOUT 1C TOO COLD AT 925MB ON AVERAGE. AFTER HAVING THREE WINTRY PCPN EVENTS IN THE FIRST FIVE DAYS OF MARCH, THE LONG TERM REMAINS RELATIVELY MORE SUBDUED WITH A MUCH ANTICIPATED RETURN (EVEN IF ITS JUST FOR A COUPLE OF DAYS) OF NEAR NORMAL TEMPERATURES. THE ONE CHANGE TONIGHT VS LAST NIGHT IS THE INCREASING CHANCE THAT A SOUTHERN STREAM SYSTEM MIGHT BRING SOME RAIN INTO THE REGION ON TUESDAY. THE MODERATING TREND WILL START ON SATURDAY AFTER A COLD COLD COLD MORNING. MID LEVEL WAA ASSOCIATED WITH A CLIPPER LOW PRESSURE SHOULD BRING MID AND HIGH LEVEL CLOUDS INTO OUR CWA, ESPECIALLY NORTH. IN SPITE OF THIS, WE WENT TOWARD THE HIGHER SET OF STAT GUIDANCE. TODAY (FRIDAY) WILL BE A GOOD LITMUS TEST IF STAT GUIDANCE COLD BIAS IN SPITE OF AMPLE SNOW COVER CONTINUES. AS FAR AS SNOW SHOWERS, THERE HAS NOT BEEN MUCH OF A CHANGE TO THE GEOGRAPHICAL EXTENT OF MEASURABLE PCPN REACHING DEEPER INTO OUR CWA. ONLY CHANGE WE MADE, WAS TO START THE LOW CHANCE OF SNOW SHOWERS FAR NORTH ON SATURDAY AFTERNOON. THE WEAK COLD FRONT ASSOCIATED WITH THE CLIPPER SHOULD PASS THROUGH OUR CWA ON SATURDAY NIGHT. NOT MUCH DEEP MOISTURE TO GENERATE SHOWERS. LOW CHANCE FOR SNOW SHOWERS WAS KEPT FAR NORTH. MODELS ARE INDICATING MORE LOW LEVEL CLOUDS (POSSIBLY TRAPPED UNDER AN INVERSION NORTH) AROUND AND THIS IS REASON FOR MUCH HIGHER MINS. ON SUNDAY, SOME WEAK PVA AND A JET STREAK ARE PREDICTED TO PASS ACROSS OUR CWA, LEANING NORTH. STILL TOO EARLY TO TELL IF WE HAVE THE GEOGRAPHY STRAIGHT, THE JET STREAK ITSELF LOOKS MORE CERTAIN. WE PUT IN A CHANCE OF FLURRIES NORTH AS A PROXY. WHILE SOUNDINGS SUGGEST LACK OF ICE COULD BE A PROBLEM (ESPECIALLY ON THE MOISTURE TRAPPED NAM SOUNDINGS), WESTERLY WINDS ARE NORMALLY NOT A FREEZING DRIZZLE DIRECTION IN OUR AREA. WHILE COLDER AIR (RELATIVE TO SATURDAY) IS PREDICTED TO MOVE INTO OUR AREA, IT WARMS BEYOND SATURDAY AT 925MB. THUS REASON FOR BUMP UP IN MAX TEMPS. A HIGH PRESSURE SYSTEM BRIEFLY BUILDS INTO THE AREA ON MONDAY. BY THEN AIR MASS IS EVEN SLIGHTLY WARMER AND WE EXPECT THE SNOW COVER TO BE LOSING ITS EFFECTIVENESS ON SLOWING THE RISE OF MAX TEMPS. CHANGE THEN COMES LATE MONDAY NIGHT AND MORE SO TUESDAY AS ALL THE RUNS HAVE TRENDED NORTH WITH A LOW FORMING OFF THE OLD STALLED FRONT. UNLESS PCPN FLIES IN ON MONDAY NIGHT, THERMALLY IT LOOKS WARM ENOUGH FOR RAIN, ESPECIALLY GIVEN SOUTH IS FAVORED OVER NORTH. FASTER TIMING COUPLED WITH A MORE NORTHERN EXTENSION MIGHT BE PROBLEMATIC FOR PTYPE. IN ITS WAKE, AN EVEN MILDER DAY IS PREDICTED FOR WEDNESDAY BEFORE A CANADIAN HIGH PRESSURE SYSTEM BRINGS COLDER AIR BACK INTO OUR CWA POSSIBLY AS SOON AS THURSDAY. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS EXPECTED TODAY AND TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST TODAY AND SKIES WILL BE MAINLY CLR THIS MORNING AND THEN SOME INCREASING HIGH CLOUDS FOR THE AFTERNOON. WINDS WILL BE NORTHERLY OR NORTHWEST AROUND 10 KTS EARLY TODAY THEN GO LIGHT WEST/SOUTHWEST TONIGHT. OUTLOOK... SATURDAY...VFR OVERALL. SATURDAY NIGHT THROUGH SUNDAY...SOME MVFR CONDITIONS DUE MAINLY TO CIGS AS A WEAK SYSTEM MOVES BY LATER SATURDAY. HOWEVER, ANY PRECIPITATION LOOKS TO REMAIN NORTH AND WEST OF THE TERMINALS. SUNDAY NIGHT THROUGH MONDAY NIGHT...VFR OVERALL. TUESDAY...CHANCE OF MVFR CONDITIONS AT SOUTHERN AIRPORTS AND TERMINALS. PTYPE SHOULD BE RAIN. && .MARINE... THE SCA HAS BEEN ALLOWED TO EXPIRE ON THE LOWER BAY AND IN THE WATERS OFF OF SANDY HOOK AS SEAS HAVE FALLEN TO AROUND 2-3 FEET IN THESE ZONES AND WINDS ARE GUSTING TO 20 KNOTS OR LESS. THESE VALUES WILL DECREASE SOME THIS AFTERNOON. THE SCA HAS BEEN EXTENDED FURTHER SOUTH TILL 1PM AS SEAS ARE STILL RUNNING FROM FIVE TO SIX FEET BUT DECREASING. OUTLOOK... SATURDAY AND SATURDAY NIGHT...THE CONDITIONS ARE EXPECTED TO BE BELOW SMALL CRAFT ADVISORY CRITERIA, HOWEVER THE WINDS WILL INCREASE SOME FROM THE WEST-SOUTHWEST DURING SATURDAY. THERE IS A CHC FOR SOME LIGHT FREEZING SPRAY SATURDAY MORNING. SUNDAY THROUGH MONDAY NIGHT...WE ARE ANTICIPATING SUB SMALL CRAFT ADVISORY CONDITIONS AS A WEAK FRONT MOVES THROUGH. TUESDAY...THERE IS A CHANCE OF SMALL CRAFT ADVISORY CONDITIONS PENDING THE PROXIMITY OF THE TRACK OF A LOW PRESSURE SYSTEM PREDICTED TO FORM OFF THE NORTH CAROLINA COAST. && .CLIMATE... WITH A SNOW COVER IN PLACE AND ANOTHER ARCTIC AIRMASS SETTLING INTO THE REGION AND RADIATIONAL COOLING OCCURRING WE HAVE ANOTHER CHANCE FOR MORE RECORD LOWS ACROSS THE REGION. FRIDAY 3/6 RECORD LOWS ACY 10 1888 PHL 10 1978 ILG 11 1926 ABE 7 1960 TTN 7 1872 GED 10 1978 RDG 7 1978 MPO -5 1909 SATURDAY 3/7 RECORD LOWS ACY 10 1890 PHL 9 1960 ILG 11 1960 ABE 1 1960 TTN 7 1890 GED 3 1960 RDG 10 1989 MPO -18 1911 IT APPEARS THAT READING AND ATLANTIC CITY HAVE THE BETTER CHANCE OF GETTING TO THEIR RECORD LOW SATURDAY MORNING. RECORD DAILY SNOWFALL FOR THURSDAY MARCH 5 RER`S POSTED FOR KILG AND KACY...BOTH 7.0 INCHES. PHL HAD 7.5 AND ALLENTOWN 6.7. KACY 0.3 - 1960 KILG 3.7 - 1981 KABE 7.0 - 1917 KPHL 8.8 - 1981 FWIW...WATER EQUIVALENCE OF TOTAL SNOW DEPTH IN PORTIONS OF EASTERN PA IS NOW WELL OVER 3 INCHES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ451>455. && $$ SYNOPSIS...GIGI/GORSE NEAR TERM...GAINES/O`HARA SHORT TERM...O`HARA LONG TERM...GIGI AVIATION...GIGI/GORSE/O`HARA MARINE...GAINES/GIGI/GORSE CLIMATE...

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