Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 011033 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 633 AM EDT WED APR 1 2015 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO OUR REGION FROM HUDSONS BAY TODAY AND SLOWLY MOVE OFFSHORE ON THURSDAY. A WARM FRONT WILL MOVE NORTHWARD THROUGH OUR AREA THURSDAY NIGHT...FOLLOWED BY A STRONG COLD FRONTAL PASSAGE SATURDAY MORNING. A WEAKER COLD FRONT WILL GRADUALLY MOVE SOUTHWARD INTO OUR REGION SUNDAY NIGHT...AND MAY STALL OVER THE MID ATLANTIC THROUGH MID-WEEK...AS WAVES OF LOW PRESSURE MOVE ALONG IT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WE ADDED SOME ADDITIONAL CLOUDINESS FIRST PART OF THIS MORNING NORTHERN PART OF OUR CWA NORTH OF THE CHANNELIZED VORT MAX. GFS INITIALIZATION LOOKED BETTER AT 500MB WHILE THE NAM/WRF WAS BETTER AT 850 MB AND 925MB. GFS 1C TOO COLD AT SEVERAL SITES. OVERALL A QUIET, BUT CHILLY START TO APRIL ACROSS OUR CWA. THE CLIPPER SYSTEM IS WELL OFFSHORE AND SFC HIGH PRESSURE WILL BE MOVING EAST TODAY. INTO EARLY THIS AFTERNOON A CHANNELIZED VORT MAX IS YET TO CLEAR OUR CWA. THERE IS SOME MAINLY MID LEVEL MOISTURE NORTH OF THIS FEATURE IN THE GREAT LAKES THAT WILL BE PASSING ACROSS OUR CWA (MORE NORTH THAN SOUTH). ALSO SOUNDINGS ARE SHOWING CONVECTIVE TEMPS GETTING REACHED NORTH. THINK THE GFS TRAPPED MOISTURE LOOKS OVERDONE GIVEN LACK OF LOW LEVEL CLOUDINESS ALREADY AND COLD INITIALIZATION OF 850 MB AND 925MB TEMPS. OVERALL EVEN NORTH THERE SHOULD BE SUFFICIENT SUNSHINE AND IT WILL BE LESS OF A CLOUD ISSUE SOUTH. WITH THE CHANNELIZED VORT MOVING OFFSHORE, SKIES SHOULD BECOME SUNNIER AS THE AFTERNOON PROGRESSES. STAT GUIDANCE LOOKS PRETTY MUCH SPOT ON FOR MAX TEMPS TO METHODS WE NORMALLY FOLLOW. UP NORTH PREFER HIGHER NAM MOS BECAUSE OF THE COLD INITIALIZATION BY THE GFS. IT MIGHT BE GIVING YESTERDAY`S SNOW TOO MUCH CREDIT. NORTHWEST WINDS NOT THAT BRISK FOR APRIL, LIKELY PEAK GUSTS FOR THE DAYTIME AROUND 20 MPH. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... BECAUSE OF THE UNSEASONABLY COLD FEBRUARY AND MARCH WE ARE DELAYING THE START OF FROST AND FREEZE PRODUCTS FOR THE DELMARVA UNTIL APRIL 11TH. EVEN LOCALLY, WE ARE WAY BEHIND. OUR NEIGHBOR`S BEAUTIFUL WHITE MAGNOLIA TREES THAT NORMALLY BLOOM LIKE CLOCKWORK ON THE FIRST DAY OF SPRING ARE NOT EVEN CLOSE, ESTIMATING WE ARE ABOUT TWO WEEKS BEHIND SCHEDULE. SPEAKING OF FROST WITH THE HIGH PRESSURE SYSTEM PASSING OVER OUR CWA TONIGHT, EXCELLENT RADIATIONAL COOLING CONDITIONS ARE EXPECTED. THE GRADIENT STARTS TO TIGHTEN TOWARD MORNING, BUT SUSPECT THE RADIATIONAL INVERSION WILL PREVENT MIXING. AT THE NORTH END OF OUR CWA SOME HIGH LEVEL CLOUDS SHOULD ARRIVE TOWARD MORNING. BECAUSE WE ARE ON THE CONVERGENT SIDE OF THE JET AND STRONG RIDGING IS PREDICTED OVERNIGHT, DO NOT BELIEVE THEY WILL HAVE MUCH OF A THERMAL IMPACT. THUS MIN TEMPS IN OUTLYING AREAS ARE AT OR BELOW STAT GUIDANCE. CLOSER TO STAT GUIDANCE IN URBAN AND COASTAL AREAS. THE GFS BRINGS MEASURABLE PCPN EVER SO CLOSE TO NJ TOWARD MORNING, OVER THE PAST MONTH IN THE 24 TO 36 HR FORECAST TIME FRAME, ITS EQUITABLE THREAT SCORE IS LOWER AND ITS (WET) BIAS WITH THE .01 ISOHYET IS HIGHER THAN THE SREF, NAM OR ECMWF IN OUR REGION. BTW AT 24 HOURS THE ECMWF AND AT 36 HR THE NAM HAS HAD THE HIGHEST SCORE WITH THAT ISOHYET. THAT BEING SAID, THE GFS KEEPS PREDICTED OMEGA, THETA E RDGG AND MID LEVEL WAA NORTH OF OUR CWA, SO NO PCPN CORROBORATION. && .LONG TERM /THURSDAY THROUGH TUESDAY/... THE MID-LEVEL PATTERN FEATURES A RIDGE CRESTING OVER THE NORTHEAST CONUS FRI NIGHT...WITH THE FLOW BACKING SOUTHWEST...FOLLOWED BY THE PASSAGE OF A STRONG S/WV ON SATURDAY. THEREAFTER...COMPLEX PATTERN SETS UP AS TROUGH SETS UP OVER THE WESTERN US AND DOWNSTREAM FLOW BECOMES WEST-SOUTHWEST OVER THE ERN CONUS. THE 00Z/01 MODEL SUITE DISAGREEMENT CENTERS AROUND MAGNITUDE OF S/WV ENERGY ENTERING THE WESTERN CONUS TROUGH AND UPPER MS VALLEY EARLY NEXT WEEK. THE EC/UKMET SOLUTION FAVORS A MORE ZONAL FLOW OVER THE NORTHEAST CONUS WHICH LEADS TO A STATIONARY FRONT INVOF THE MID ATLANTIC...WHILE THE GFS SOLUTION FAVORS MORE OF A MERIDIONAL FLOW WHICH PLACES THIS FRONT FURTHER TO THE NORTH. DAY TO DAY...EXPECTING TEMPS ABV AVERAGE ON THU AND FRI W/GUSTY SOUTHWEST WINDS LIKELY. A GENERALLY DRY DAY EXPECTED THU WITH SHOWERS AND THUNDERSTORMS LIKELY FRI AS A COLD FRONT APPROACHES FROM THE WEST. AS THE COLD FRONT CROSSES THE AREA EARLY SAT... IT WILL TURN BLUSTERY AND PRECIP MAY TURN TO SNOW OVER THE HIGHER TERRAIN...DEPENDING ON THE THERMAL PROFILE. THIS BEARS WATCHING. A BRIEF REPRIVE ON SUNDAY BEFORE A STATIONARY BOUNDARY ATTEMPTS TO SETUP INVOF THE MID ATLANTIC IN THE MON THRU WED TIME FRAME. THIS FAVORS AN OVERRUNNING REGIME...AND WITH THE ADDITION OF GULF MOISTURE...HEAVY RAINFALL IS A POSSIBILITY DURING THIS TIME FRAME. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. NO BIG CHANGES WITH THE 12Z TAFS. THIS MORNING...VFR. SOME SCATTERED MID LEVEL CLOUDS. COULD BE A CIG EARLY NORTH, BUT SHOULD AVERAGE SCATTERED OVERALL. LATER A CUMULUS DECK OF CLOUDS SHOULD START FORMING. NORTHWEST WINDS SHOULD AVERAGE 10 TO 15 KTS. WE MIGHT HAVE SOME GUSTINESS, BUT BELIEVE THEY SHOULD BE UNDER 20 KTS AND HAVE NOT CARRIED THEM AT ANY TAF SITE. THIS AFTERNOON...A VFR CU BASED CIG MIGHT FORM AT NORTHERN AND PA AIRPORTS AND TERMINALS. ELSEWHERE WE ARE EXPECTING THEM TO BE SCATTERED OR LESS. WINDS SHOULD BACK EVER SO SLIGHTLY MORE TO THE WEST WITH SIMILAR SPEEDS. NO CHANGE TO GUSTINESS THINKING. TONIGHT...LIGHT WINDS, NO VSBY RESTRICTIONS EXPECTED. SOME CIRRUS CLOUDS WILL PASS BY AFTER MIDNIGHT. OUTLOOK... THURSDAY...VFR CONDITIONS EXPECTED. THURSDAY NIGHT AND FRIDAY...MVFR POSSIBLE IN SHRA AND TSRA. SATURDAY...MVFR IN SHRA EARLY...GRADUALLY IMPROVING TO VFR. SUNDAY AND MONDAY...GENERALLY VFR WITH MVFR POSSIBLE IN SHRA. && .MARINE... THE SMALL CRAFT ADVISORY WILL BE CONTINUED FOR LOWER DELAWARE BAY AND THE OCEAN INTO THE FIRST PART OF THE MORNING. COMBINATION OF A RELAXING GRADIENT AND INCREASING AIR TEMPERATURES SHOULD BRING US BELOW SMALL CRAFT ADVISORY CRITERIA BY THE END OF THE MORNING. THEN WITH THE HIGH PRESSURE SYSTEM NEARING OUR AREA, SUB SMALL CRAFT ADVISORY CONDITIONS WILL CONTINUE THROUGH TONIGHT. OUTLOOK... THURSDAY AND FRIDAY...SEAS ARE EXPECTED TO REACH SCA CRITERIA LATE ON THU AND CONTINUE THRU SATURDAY. MEANWHILE...SOUTHWEST WINDS ON THU AND FRI ARE ANTICIPATED TO VEER NORTHWEST BY FRI NIGHT... AND REMAIN AOB THE SCA THRESHOLD DURING THIS TIME FRAME. SUNDAY AND MONDAY...WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW THE SCA THRESHOLD ATTM. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EDT THIS MORNING FOR ANZ431- 450>455. && $$ SYNOPSIS...FRANCK NEAR TERM...GIGI SHORT TERM...GIGI LONG TERM...FRANCK AVIATION...FRANCK/GIGI MARINE...FRANCK/GIGI

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