Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 211308 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 908 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/... THE LATEST MODEL GUIDANCE, INCLUDING THE 1100 UTC HRRR, SUGGESTS THAT THE FARTHEST NORTHWARD EXTENT OF THE RADAR ECHOES IN AND NEAR OUR REGION WILL OCCUR DURING THE LATE MORNING HOURS. THE RADAR ECHOES/LIGHT RAIN SHOWERS PASSING ACROSS NORTH CENTRAL AND NORTHEASTERN PENNSYLVANIA SHOULD DISSIPATE AS THEY MOVE EASTWARD AND AS THEY ENCOUNTER DRY AIR. AS A RESULT, IT CONTINUES TO APPEAR AS THOUGH THE BETTER CHANCES FOR RAIN DURING THE AFTERNOON HOURS WILL BE FROM THE PHILADELPHIA METROPOLITAN AREA AND CENTRAL NEW JERSEY SOUTHWARD. RAINFALL AMOUNTS OF 0.25 TO 0.75 INCHES ARE EXPECTED ACROSS MUCH OF NORTHEASTERN MARYLAND, DELAWARE AND SOUTHERN NEW JERSEY THROUGH THIS EVENING. A TOTAL OF 0.10 TO 0.20 INCHES IS POSSIBLE AS FAR NORTH AS PHILADELPHIA WITH LESSER AMOUNTS ANTICIPATED FOR THE CITY`S NORTHERN SUBURBS INTO CENTRAL NEW JERSEY. THE SKY WILL BE OVERCAST FOR MOST OF THE DAY WITH PERHAPS SOME BREAKS UP NORTH. THE WIND SHOULD FAVOR THE NORTHEAST AND EAST IN OUR SOUTHERN COUNTIES DUE TO THE CIRCULATION AROUND THE LOW IN THE CAROLINAS. THE WIND MAY SETTLE INTO THE SOUTHWEST IN MUCH OF EASTERN PENNSYLVANIA AND NORTHERN NEW JERSEY. SPEEDS SHOULD BE LESS THAN 10 MPH. TODAY`S TEMPERATURE FORECAST REMAINS TRICKY. ONCE THE STEADY RAIN BEGINS IN OUR SOUTHERN COUNTIES, TEMPERATURES WILL DROP A BIT, KEEPING READINGS MAINLY IN THE 50S. THE WARMEST TEMPERATURES IN OUR FORECAST AREA SHOULD BE IN THE VALLEYS UP NORTH WHERE HIGHS SHOULD GET INTO THE LOWER 60S. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... 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. && .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 AIR MASS 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 AIR MASS 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 AIR MASS ALONG WITH AN INCREASE IN THE HUMIDITY. SOME PLACES HAVE A GOOD CHC OF REACHING 90 DEGREES EACH AFTERNOON. && .AVIATION /13Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...VFR CIGS. LIGHT RAIN WILL SPREAD INTO OUR REGION FROM THE WEST AND SOUTHWEST THIS MORNING. 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. && .MARINE... 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. && .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...IOVINO SHORT TERM...DRAG LONG TERM...GORSE AVIATION...DRAG/GORSE MARINE...DRAG/GORSE FIRE WEATHER...GORSE RIP CURRENTS...DRAG CLIMATE...DRAG

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