Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 211100 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 700 AM EDT THU MAY 21 2015 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL TRACK SOUTH AND EAST OF OUR REGION LATE TODAY AND TONIGHT, THEN A COLD FRONT CROSSES OUR AREA LATER FRIDAY. HIGH PRESSURE BUILDS IN SATURDAY BUT THEN SHIFTS OFFSHORE SATURDAY NIGHT AND SUNDAY. THE NEXT COLD FRONT DROPS INTO OUR AREA SUNDAY NIGHT INTO MONDAY, THEN AS LOW PRESSURE TRACKS FROM THE PLAINS TO THE GREAT LAKES REGION THE FRONT LIFTS BACK NORTH AS A WARM FRONT LATE MONDAY INTO TUESDAY. A COLD FRONT IS FORECAST TO REMAIN WELL TO OUR WEST DURING WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
TODAY...HPC QPF AND 00Z/21 MODEL CONSENSUS HAS THE NORTHERN EDGE OF THE MEASURABLE RAIN TODAY NEAR I-95. CALLED IT SHOWERS ON THE NORTHERN EDGE OF THE RAIN SHIELD WHERE MORE SPORADIC. A PERIOD OF MDT TO HEAVY RAIN APPEARS PROBABLE FAR SE NJ AND DELAWARE. THIS 630AM FORECAST THEN TAKES INTO ACCOUNT THE HRRR AS WELL AS THE NARRE THROUGH THIS MID AFTERNOON. EXPANDED THE POTENTIAL FOR .01 NORTHWARD IN THIS ISSUANCE. CONFIDENCE ON TEMPS/POPS IS BELOW AVERAGE FROM SE PA ACROSS CENTRAL NJ WHERE GREATEST UNCERTAINTY EXISTS (KPHL- KTTN). TEMPS WILL FALL INTO THE LOW AND MID 50S WHEN THE RAIN BECOMES STEADY. A CHILLY DAY FOR THE DELMARVA. TEMPS WERE LOWERED SLIGHTLY IN THIS UPDATE. MEASURABLE RAIN IS NOT EXPECTED IN NE PA AND FAR NNJ TODAY (I80 NORTH). LIGHT WIND WILL BE N-NE EARLY THIS MORNING THEN MIDDAY-THIS AFTN BECOMES LIGHT SOUTH IN THE NORTH AND REMAINING E-NE ACROSS ACROSS THE SOUTH. WARMEST TEMPS MAY BE IN NNJ TODAY WHERE NO RAIN IS FCST. FCST BASED ON A GENERAL 50 50 BLEND OF 00Z/21 NAM/GFS MOS. CAUSE OF THE RAIN AND CLOUD COVER: INSTABILITY BURST WITH SLY FLOW 850 WAA BENEATH WSW FLOW AT MID LEVELS (700-500MB) WITH DECENT RRQ 250 JET AIDING LIFT. THIS AHEAD OF A RELATIVELY STRONG 500MB SHORT WAVE MOVING ESEWD FROM THE MIDWEST THIS MORNING AND ARRIVING IN THE UPPER OHIO VALLEY THIS EVENING.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
-- Changed Discussion --
LEFTOVER RAIN ALONG THE COAST AND A CHANCE OF A PERIOD OF RAIN OR SHOWERS ELSEWHERE EARLY, THEN CLEARING TOWARD DAWN AS THE RELATIVELY STRONG 500MB SHORT WAVE SEEN AS AN -80M 12 HR HFC PASSES THROUGH E PA REACHING LI BY DAYBREAK FRIDAY. PATCHY FOG POSSIBLE TOWARD DAWN IF IT CLEARS FAST ENOUGH AND IT REMAINS DECOUPLED THROUGH THE NIGHT. LIGHT WIND TREND W-NW OVERNIGHT.
-- End Changed Discussion --
&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/... THE SYNOPTIC SETUP IS COMPRISED OF A CLOSED LOW ACROSS EASTERN CANADA THAT SHIFTS EASTWARD FRIDAY AND OVER THE WEEKEND AS ENERGY STARTS TO EJECT INTO THE CENTRAL AND SOUTHERN PLAINS. THE LATTER WILL TEND TO BUILD A RIDGE FROM NEAR FLORIDA NORTHWESTWARD TOWARD THE MIDWEST SATURDAY INTO MONDAY. THE RIDGE THEN STRENGTHENS SOME AS IT SHIFTS EASTWARD MONDAY AND TUESDAY, HOWEVER IT SHOULD FLATTEN SOME ON ITS NORTHERN SIDE. THE MAIN FEATURE OF INTEREST IS A COLD FRONT THAT DROPS DOWN LATE SUNDAY INTO MONDAY, BUT THEN IT LIFTS BACK NORTH AS A WARM FRONT AS THE RIDGE BUILDS. IT LOOKS TO TURN RATHER WARM TO EVEN HOT NEXT WEEK AS THE UPPER-LEVEL RIDGE IS IN PLACE. WE USED A MODEL BLEND FOR FRIDAY THROUGH SUNDAY, THEN THE 00Z WPC GUIDANCE WITH CONTINUITY THEREAFTER. SOME TWEAKS WERE THEN MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES. FOR FRIDAY AND SATURDAY...THE CLOSED LOW TO OUR NORTH IS FORECAST TO BE SHIFTING EASTWARD DURING THIS TIME FRAME AS ENERGY EJECTS INTO THE CENTRAL AND SOUTHERN PLAINS. THIS WILL TAKE SURFACE LOW PRESSURE INTO THE CANADIAN MARITIMES FRIDAY AND A COLD FRONT THROUGH OUR AREA LATE IN THE DAY. WHILE THERE IS SOME INCREASE IN MOISTURE AHEAD OF THE FRONT AND ALSO SOME LOWER LEVEL INSTABILITY FORECAST, THE DEEP WESTERLY FLOW SHOULD TEND TO LIMIT THE CONVERGENCE. WHILE SOME ISOLATED SHOWERS CANNOT BE RULED OUT, WE OPTED TO KEEP THE FORECAST FRIDAY DRY ATTM. THE PRESSURE GRADIENT TIGHTENS WITH BREEZY CONDITIONS DURING FRIDAY, THEN THIS GRADUALLY RELAXES LATER FRIDAY NIGHT AND SATURDAY AS SURFACE HIGH PRESSURE MOVES IN. A MUCH DRIER AIRMASS FOLLOWS THE FRONT, AND THIS WILL SET THE STAGE FOR A CHILLY FRIDAY NIGHT AND EARLY SATURDAY. THERE COULD BE SOME FROST FORMATION EARLY SATURDAY MORNING ACROSS PORTIONS OF THE NORTHERN ZONES, PENDING WE DECOUPLE. FOR NOW, WE INCLUDED A PATCHY FROST MENTION. HIGH PRESSURE THEN BEGINS TO SHIFT OFFSHORE SATURDAY NIGHT AS RIDGING BUILDS TO OUR WEST. FOR SUNDAY AND MONDAY...A RIDGE TO OUR WEST WILL GRADUALLY BUILD EASTWARD. SOME ENERGY SLIDING SOUTHEASTWARD ACROSS NEW ENGLAND WILL DROP A COLD FRONT INTO OUR AREA SUNDAY NIGHT AND MONDAY. THIS FEATURE GENERALLY LOOKS TO BE ON THE WEAK SIDE, AND THERE IS SOME GUIDANCE THAT HOLDS THIS FRONT FARTHER TO THE NORTH IN THE FORM OF A WARM FRONT. THE FRONT DOES NOT LOOK TO STAY IN PLACE LONG AS THE BUILDING RIDGE ALOFT ALONG WITH SURFACE HIGH PRESSURE TO OUR EAST WILL HELP REINFORCE A SOUTHWESTERLY FLOW. THEREFORE THE BOUNDARY SHOULD MOVE NORTH AS A WARM FRONT DURING MONDAY AND MONDAY NIGHT. THERE MAY BE SOME CONVECTION RIDING ALONG OR NEAR THIS FRONT, HOWEVER THIS MAY NOT BE UNTIL LATE MONDAY AS THE RIDGE AXIS MOVES ACROSS. A WARMER AIRMASS SHOULD OVERSPREAD THE AREA ESPECIALLY MONDAY AS AN EXPANDING WARM SECTOR MOVES NORTH, AND SOME INCREASE IN THE DEW POINTS WILL ALSO OCCUR. FOR TUESDAY AND WEDNESDAY...WE SHOULD BE IN THE WARM SECTOR DURING THIS TIME FRAME AS A SHORT WAVE ALOFT AND SURFACE LOW TRACKS TO OUR NORTH, WHICH WILL FLATTEN THE RIDGE SOME. WHILE THE SURFACE COLD FRONT IS CURRENTLY FORECAST TO STAY TO OUR WEST, SOME CONVECTION CANNOT BE RULED OUT AS THERE ARE SOME INDICATIONS OF A LEE SIDE TROUGH DEVELOPING IN THE PRESENCE OF A WARM TO HOT AIRMASS ALONG WITH AN INCREASE IN THE HUMIDITY. SOME PLACES HAVE A GOOD CHC OF REACHING 90 DEGREES EACH AFTERNOON. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR CIGS. LIGHT RAIN IS FORECAST TO SPREAD INTO OUR REGION FROM THE WEST AND SOUTHWEST THIS MORNING. THE RAIN IS EXPECTED TO REMAIN NEAR OR JUST SOUTH OF KABE. A PERIOD OF RAIN IS ANTICIPATED FOR KILG, KPHL, KPNE AND KTTN DURING THE AFTN WITH THE CATEGORICAL RAIN PROBABILITY RESTRICTED TO KILG. CONDITIONS SHOULD REMAIN IN THE VFR CATEGORY AT THOSE LOCATIONS WITH CEILINGS STAYING ABOVE 3000 FEET AND VISIBILITY VALUES STAYING ABOVE 5 MILES. THE RAIN IS FORECAST TO HAVE A GREATER IMPACT ON KMIV AND KACY THAN ON OUR TAF SITES TO THE NORTH. CONDITIONS SHOULD DROP TO MVFR AT KMIV AND KACY THIS AFTERNOON. AFTER THIS MORNINGS LIGHT NE WIND TO START, A LIGHT SOUTHWEST WIND MAY DEVELOP AT KRDG, KABE, KTTN, KPNE, KPHL AND KILG DURING MIDDAY. THE WIND MAY REMAIN VARIABLE AT KMIV AND KACY OR IT COULD RESETTLE INTO THE NORTHEAST OR EAST DURING THE AFTERNOON HOURS AT THOSE LOCATIONS. TONIGHT...MOSTLY VFR CIGS; ALTHOUGH, SOME LINGERING RAIN/SHWRS MAY MEAN SOME SUB-VFR THROUGH THE FIRST PART OF THE NIGHT MAINLY FROM AROUND KMIV/KACY AND SOUTH. LIGHT WIND TREND W-NW OVERNIGHT. OUTLOOK... FRIDAY...VFR OVERALL. A COLD FRONT MOVES THROUGH LATER IN THE DAY WITH PERHAPS AN ISOLATED BRIEF SHOWER. WEST WINDS BECOMING NORTHWEST AND GUSTING UP TO 25 KNOTS MAINLY DURING THE AFTERNOON AND EVENING, THEN DIMINISHING. SATURDAY...VFR. NORTHWEST WINDS AROUND 10 KNOTS. SUNDAY...VFR. SOUTHWEST WINDS 10 TO 15 KNOTS, THEN TENDING TO BECOME LIGHT AND VARIABLE AT NIGHT AS A FRONT DROPS NEAR OR INTO THE AREA. MONDAY...MAINLY VFR. LIGHT AND VARIABLE WINDS BECOMING SOUTHWEST AROUND 10 KNOTS. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE ESPECIALLY IN THE AFTERNOON.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SAFE BOATING WEEK CONTINUES THROUGH FRIDAY MORNING. THERE IS A NEW USCG SAFETY APP THAT SHOULD BE OF VALUE TO MARINERS AND WAS JUST UNVEILED THIS WEEK: HTTP:/WWW.USCG.MIL/MOBILE THIS APP PROVIDES ADDITIONAL SAFE BOATING RESOURCES FOR MOBILE DEVICE USERS. WHEN LOCATION ENABLED, USERS CAN RECEIVE THE LATEST WEATHER REPORTS FROM THE CLOSEST NOAA BUOY AS WELL AS REPORT THE LOCATION OF A HAZARD ON THE WATER. IT FEATURES AN EMERGENCY ASSISTANCE BUTTON, WHICH CAN CALL THE CLOSEST CG COMMAND CENTER. THE FORECAST: ISSUED SCA FOR THE DE BAY ATLC WATERS TONIGHT. NCAROLINA LOW INTENSIFIES IN ITS DEPARTURE AND SHOULD DEVELOP MARGINAL 5 FT HAZARDOUS SEAS AND A FEW SCA GUSTS AROUND 25 KT OVERNIGHT NEAR 44009. OTHERWISE NO MARINE HEADLINE ANTICIPATED THROUGH TONIGHT. NORTHERLY WINDS EARLY TODAY TEND NORTHEAST NORTHEAST-EAST BY DAYBREAK THEN ONSHORE SOUTHEAST THIS AFTERNOON. WINDS EVENTUALLY BECOMING NORTHWEST EVERYWHERE LATER THIS THURSDAY NIGHT. OUTLOOK... FRIDAY...A COLD FRONT MOVES THROUGH THE AREA LATE IN THE DAY AND THE EVENING AS LOW PRESSURE MOVES AWAY, WITH A NORTHWEST WIND IN ITS WAKE. PRIOR TO THIS, SOME GUSTS TO NEAR 25 KNOTS SHOULD LINGER ACROSS THE FAR SOUTHERN COASTAL WATERS EARLY. THE FORECAST SOUNDINGS SHOW BETTER MIXING MOSTLY NEARSHORE DURING THE DAY, THEN EXPANDING TO OFFSHORE AT NIGHT AS COLDER AIR MOVES IN AND THEREFORE A SMALL CRAFT ADVISORY MAY BE NEEDED FOR LATER FRIDAY NIGHT. SATURDAY AND SUNDAY...NORTHWEST WIND GUSTS TO 25 KNOTS MAY OCCUR TO START SATURDAY, OTHERWISE THE CONDITIONS SHOULD BE BELOW ADVISORY CRITERIA. MONDAY...A SOUTHWESTERLY FLOW IS ANTICIPATED TO INCREASE SOME, HOWEVER THE CONDITIONS OVERALL SHOULD BE BELOW ADVISORY CRITERIA. SOME SHOWERS AND THUNDERSTORMS ARE POSSIBLE.
-- End Changed Discussion --
&& .FIRE WEATHER... FOR FRIDAY AFTERNOON, THERE MAY BE THE RISK FOR ENHANCED WILDFIRE SPREAD AS WEST-NORTHWEST WINDS GUST TO 20-25 MPH AT TIMES. IN ADDITION, THIS WILL COMBINE WITH RELATIVE HUMIDITY VALUES DROPPING TO AROUND 30 PERCENT IN SOME AREAS ALONG WITH DRY FINE FUELS. THIS WILL DEPEND ON HOW MUCH WETTING OCCURS LATER TODAY ESPECIALLY ACROSS THE SOUTHERN AREAS. && .RIP CURRENTS... SST`S ABOVE NORMAL AND JUST OFF THE COAST SSTS WELL ABOVE NORMAL BY ALMOST 3C. THIS IS NOT GOOD ONCE IT TURNS HOT AND BEACHES ARE UNGUARDED, SWIMMERS MAY TAKE CHANCES AT UNGUARDED LOCATIONS. BE SMART ABOUT ANY SWIMMING EARLY THIS SEASON. ATLANTIC COASTAL WATER TEMPS ARE WARMING --UPPER 50S TO MID 60S. RIP CURRENT AWARENESS WEEK FOR MT HOLLY IS JUNE 7-13 WITH PSAS VIA PUBLIC INFORMATION STATEMENTS, SOCIAL MEDIA, NOAA WEATHER RADIO AND ANY MEDIA INTERVIEWS DESIRED (CONTACT OFFICE). FOR RIP CURRENTS: DESPITE ANTICIPATED PROJECTIONS OF LOW OR MODERATE RISK THROUGH THE MEMORIAL DAY WEEKEND, EARLY SEASON FATALITIES OCCUR WHEN SWIMMING AT UNGUARDED TIMES/LOCATIONS. WEAKER SWIMMERS OR SWIMMING IN AREAS WHERE RIP CURRENTS ARE STRONGER (JETTIES) CAN QUICKLY BECOME LIFE THREATENING. WHEN TRAINED LIFEGUARDS ARE NOT NEARBY, TIMELY RESCUE IS MUCH LESS LIKELY. LETS GET THROUGH THE MONTH OF MAY WITH ALL SWIMMERS SAFE! SWIM IN THE PRESENCE OF LIFE GUARDS! THANK YOU. && .CLIMATE... **TOP 10 WARMEST MAY CONTINUES LIKELY IN PORTIONS OF THE FORECAST AREA** THE FIRST 19 DAYS OF MAY IN OUR FORECAST AREA WERE AVERAGING WITHIN ABOUT 1/2 DEGREE OF 7 DEGREES ABOVE NORMAL. BASED ON THE ENSEMBLE AND A FORECAST THAT IS DETERMINISTICALLY CONSERVATIVE INCLUDING OUR 330 PM MAY 20 PROJECTIONS THROUGH THE 27TH AND THEN THE 00Z/21 CONSERVATIVE FTPRHA THEREAFTER THROUGH THE 31ST...EASILY OUTLOOKS A TOP 10 WARMEST MAY ON RECORD. FOR PHILADELPHIA...PERIOD OF RECORD BACK TO 1874. PROJECTING AN AVG TEMP OF 68.7 TO 69.3 OR AROUND 5 DEGREES ABOVE NORMAL AND AT THE LEAST, 3RD WARMEST ON RECORD. WARMEST WAS 70.8 IN 1991. THEN 69.2 2004. FOR ALLENTOWN...POR TO 1922. YESTERDAY WE WERE PROJECTING 65.0 OR 5.1 DEGREES ABOVE NORMAL AND 8TH WARMEST ON RECORD. WARMEST WAS 67.2 IN 1991. POSTED BECAUSE WE`RE EXPECTING OUR FIRST 90 IN PHILADELPHIA BY THE MIDDLE OF NEXT WEEK. NORMAL FIRST DATE OF 90 OR HIGHER. PHILADELPHIA MAY 29 ALLENTOWN MAY 30 WILMINGTON JUNE 4 ATLANTIC CITY JUNE 11. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 8 AM EDT FRIDAY FOR ANZ455. && $$ SYNOPSIS...GORSE NEAR TERM...DRAG 7A SHORT TERM...DRAG LONG TERM...GORSE AVIATION...DRAG/GORSE 7A MARINE...DRAG/GORSE FIRE WEATHER... RIP CURRENTS... CLIMATE...

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.