Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 060054 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 854 PM EDT TUE MAY 5 2015 .SYNOPSIS... A COLD FRONT WILL SLOWLY MOVE THROUGH OUR REGION OVERNIGHT AND WEDNESDAY. HIGH PRESSURE WILL THEN MOVE INTO THE AREA FROM THE NORTH AND EAST ON THURSDAY THROUGH THE WEEKEND. ANOTHER SLOW MOVING COLD FRONT WILL APPROACH OUR AREA EARLY NEXT WEEK...AND MOVE THROUGH THE REGION BY MID WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... WE ARE ANTICIPATING AN INCREASE IN CLOUD COVER OVERALL FOR THE NIGHTTIME PERIOD. ADDITIONAL MID LEVEL CLOUDS ALONG WITH SOME STRATOCUMULUS SHOULD OVERSPREAD OUR REGION FROM THE WEST. THE SHOWERS AND ISOLATED THUNDERSTORMS THAT EXTENDED FROM EASTERN MARYLAND SOUTHWESTWARD TO CENTRAL VIRGINIA AROUND 845 PM WILL CONTINUE TO PUSH TO THE SOUTHEAST. MEANWHILE, THE AREA OF SHOWERS OVER WESTERN NEW YORK AND PARTS OF NORTHERN PENNSYLVANIA ARE FORECAST TO SLIDE TO THE EAST SOUTHEAST. THEY SHOULD AFFECT OUR NORTHERN COUNTIES OVERNIGHT. THE SCATTERED SHOWERS THAT WERE OVER CENTRAL PENNSYLVANIA ARE EXPECTED TO DISSIPATE FOR THE MOST PART AS THEY MOVE EASTWARD. BASED ON THE RADAR TRENDS, WE WILL CONTINUE TO MENTION ONLY ISOLATED TO SCATTERED RAIN SHOWERS FOR THE OVERNIGHT PERIOD. RAINFALL AMOUNTS ARE ANTICIPATED TO BE MODEST, GENERALLY A TRACE TO A TENTH OF AN INCH. THE SURFACE FRONT WAS RATHER DIFFUSE AND DIFFICULT TO FIND THIS EVENING. IT APPEARED TO EXTEND WESTWARD FROM SOUTHERN NEW ENGLAND INTO NORTHERN PENNSYLVANIA AROUND 845 PM. THE BOUNDARY IS EXPECTED TO MOVE SOUTHWARD THROUGH MOST OF OUR FORECAST AREA BY MORNING. THE WIND IS FORECAST TO REMAIN LIGHT FOR TONIGHT. IT WILL FAVOR THE WEST AND NORTHWEST THIS EVENING AND IT SHOULD VEER TOWARD THE NORTH AND NORTHEAST LATE TONIGHT. LOW TEMPERATURES ARE EXPECTED TO RANGE FROM AROUND 50 IN THE NORTH TO NEAR 60 IN THE SOUTH. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... THE FRONT IS EXPECTED TO BE SOUTH OF OUR FORECAST AREA ON WEDNESDAY MORNING. THERE ARE A COUPLE OF MORE VORTICITY IMPULSES THAT ARE FORECAST TO SLIDE ACROSS THE AREA WEDNESDAY. THERE WILL REMAIN DECENT MOISTURE AROUND BEHIND THE FRONT, WITH PW VALUES NEAR 1.0-1.25 INCHES, SO WE WILL KEEP ISOLATED/SCATTERED SHOWERS IN THE FORECAST THROUGH THE DAY WEDNESDAY. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... OVERVIEW... MID-LEVEL RIDGE SLOWLY MOVES OVER THE NORTHEAST CONUS THU THRU SAT...WITH WEAK S/WV DISTURBANCES TRAVERSING IT. MEANWHILE...A CUT-OFF LOW DEVELOPS INVOF THE SOUTHEAST US COAST...AND THIS MAY ACQUIRE SUBTROPICAL CHARACTERISTICS DURING THIS TIME FRAME. OVERALL...THERE WILL BE A GENERAL BLOCKING PATTERN ALONG THE EAST COAST WHICH MAY BECOME REX-LIKE ATTMS. THIS WILL LEAD TO A RIDGE OF HIGH PRES AT THE SURFACE THROUGH THE WEEKEND...AND GRADUALLY GIVE WAY TO A COOL FRONT APPROACHING FROM THE NW BY EARLY NEXT WEEK. GENERALLY FAIR WX EXPECTED THRU THE WEEKEND... WITH AN INCREASING CHANCE OF SHRA/TSRA WITH THE APPROACH OF COOL FRONT SUN THROUGH EARLY NEXT WEEK. MAX TEMPERATURES WILL BE NEAR AVERAGE THRU THE PERIOD...COOLER NEAR THE COAST THU THROUGH SAT WITH ONSHORE FLOW. BY SUNDAY...THE AIR MASS MAY TURN INCREASINGLY HUMID. DAILIES... WEDNESDAY NIGHT...A WEAK S/WV WILL MOVE THROUGH THE REGION WITH FAVORABLE JET DYNAMICS. THIS WILL LEAD TO SOME OVERRUNNING ALONG A SLOW MOVING FRONTAL BOUNDARY JUST TO OUR SOUTH. WEAK LIFT AND LIMITED MOISTURE MAY SUPPORT SOME -SHRA OVER THE SOUTHWEST CWA. THURSDAY AND FRIDAY...BOTH DAYS WILL FEATURE A WEAK S/WV MOVING THRU THE REGION DURING THE AFTERNOON TIME FRAME. THIS INDUCES A WEAK SFC TROF...WITH A SEA-BREEZE ALONG THE COAST...WHICH WILL ENHANCE SFC CONVERGENCE. THERE WILL BE MORE MOISTURE AVAILABLE ON THURSDAY...SO -SHRA ARE POSSIBLE...MAINLY NORTHWEST OF THE I-95 CORRIDOR. STABILITY INDICES DO NOT SUPPORT THUNDER ATTM. ALSO...THERE MAY BE SOME PATCHY FOG FRI AM...MAINLY OVER THE NORTHWEST INTERIOR...PER SYNOPTIC PATTERN AND MODEL SOUNDINGS. SATURDAY AND SUNDAY...RIDGE BUILDS SURFACE AND ALOFT ON SAT... AND GRADUALLY MOVES SOUTHEAST ON SUNDAY. SFC FLOW GRADUALLY VEERS FROM THE SOUTHEAST ON SATURDAY TO SOUTHWEST ON SUNDAY. A COOL FRONT WILL APPROACH THE SAINT LAWRENCE VALLEY BY 00Z SUNDAY...WITH THE GFS MUCH MORE PROGRESSIVE THAN THE EURO THEREAFTER WITH THE SOUTHWARD PROGRESSION OF THE FRONT. GIVEN THE BLOCKING PATTERN ALONG THE EAST COAST...AND THE RIDGE ANCHORED OVER THE MID- ATLANTIC...FAVOR THE SLOWER SOLUTION. FEEL GENERAL SUBSIDENCE WILL KEEP THE COLUMN DRY/CAPPED ACROSS THE CWA...BUT CANNOT RULE OUT -SHRA/TSRA MAKING IT INTO THE NW PORTION OF THE CWA ON SUN AFTN. MONDAY AND TUESDAY...AS THE COOL FRONT APPROACHES...THERE WILL BE GREATER MOISTURE, LIFT, AND INSTABILITY AVAILABLE. GIVEN A SLOW FRONTAL PASSAGE WITH AMPLE GULF/SUBTROPICAL MOISTURE, AND FAVORABLE JET DYNAMICS...HEAVY RAINFALL IS POSSIBLE DURING THIS TIME FRAME. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. WE WILL CONTINUE TO FORECAST VFR CONDITIONS THROUGH THE TAF PERIOD. SCATTERED TO ISOLATED LIGHT RAIN SHOWERS SHOULD HAVE LIMITED IMPACT ON OUR TAF SITES. A LIGHT AND VARIABLE WIND OVERNIGHT SHOULD SETTLE INTO THE NORTHEAST ON WEDNESDAY MORNING AROUND 5 TO 10 KNOTS. THE WIND DIRECTION IS ANTICIPATED TO VEER TOWARD THE EAST FOR WEDNESDAY AFTERNOON. OUTLOOK... WED NIGHT AND THU...GENERALLY VFR...EXCEPT MVFR POSSIBLE IN -SHRA... MAINLY CONFINED TO PHL, PNE, ILG, ABE, RDG. FRI THRU SAT NIGHT...VFR CONDITIONS EXPECTED. SUN...VFR CONDITIONS MAY DETERIORATE TO MVFR OVER THE INTERIOR IN AFTN SHRA/TSRA. && .MARINE... SUB-SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TONIGHT INTO WEDNESDAY. SEAS WILL REMAIN 3-4 FEET, AND SOUTH-SOUTHWEST WINDS. HOWEVER, AS THE FRONT PASSES THROUGH, WINDS WILL DIMINISH AND BECOME NORTHEAST. OUTLOOK... THU THRU SAT...PERSISTENT ONSHORE OUT OF THE SOUTHEAST. WINDS ARE EXPECTED TO REMAIN BELOW SCA CRITERIA. HOWEVER...THERE IS A LOW PROBABILITY THAT SEAS MAY APPROACH SCA LEVELS BY SATURDAY. SUN...SUB-SCA CONDITIONS EXPECTED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...FRANCK NEAR TERM...IOVINO SHORT TERM...ROBERTSON LONG TERM...FRANCK AVIATION...FRANCK/IOVINO MARINE...FRANCK/ROBERTSON

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