Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Graphics & Text | 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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 230816 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 416 AM EDT THU APR 23 2015 .SYNOPSIS...
-- Changed Discussion --
A WEAKER SECONDARY COLD FRONT WILL CROSS THE AREA TODAY. A HIGH PRESSURE SYSTEM WILL BRIEFLY BUILD OVER THE REGION FRIDAY INTO EARLY SATURDAY. LOW PRESSURE IS THEN FORECAST TO PASS BY TO OUR SOUTH FROM SATURDAY NIGHT INTO SUNDAY, TRACKING FROM AROUND THE TENNESSEE VALLEY TO OFF THE CAROLINA COAST. ANOTHER HIGH PRESSURE SYSTEM SHOULD BRIEFLY BUILD INTO THE AREA ON MONDAY AND TUESDAY. THEN A LOW PRESSURE SYSTEM PREDICTED TO FORM IN THE GULF OF MEXICO SHOULD REACH THE NORTH CAROLINA COASTAL WATERS ON WEDNESDAY.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
AN AREA OF LOW PRESSURE WILL REMAIN NEARLY STATIONARY AND CONTINUE TO SPIN ACROSS SOUTHEASTERN CANADA TODAY. STRONG NORTHWEST WINDS WILL CONTINUE FOR TODAY, WITH GUSTS OF AT LEAST 25-30 MPH EXPECTED DURING THE DAY. A WEAK COLD FRONT/SURFACE TROUGH IS FORECAST TO SLIDE ACROSS THE AREA DURING THE DAY. AS THIS HAPPENS, LOW-MID LEVEL LAPSE RATES ARE FORECAST TO INCREASE AND THERE IS SOME MOISTURE FORECAST TO MOVE ACROSS THE AREA. THIS COULD LEAD TO SOME ISOLATED SHOWER ACTIVITY DEVELOPING TO OUR WEST AND MOVING INTO OUR AREA. FOR NOW, THE GREATEST POSSIBILITY IS FOR OUR NORTHWESTERN THIRD OF THE AREA. ITS POSSIBLE SOME SPRINKLES COULD MAKE IT DOWN INTO THE TIER OF COUNTIES DOWN, SO WE`VE INCLUDED A CHANCE OF SPRINKLES THERE.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
-- Changed Discussion --
ANY SHOWERS AND/OR SPRINKLES ARE EXPECTED TO DISSIPATE BY THIS EVENING AS DAYTIME INSTABILITY IS LOST AND THE SURFACE TROUGH MOVES EASTWARD. SKIES WILL LIKELY REMAIN PRETTY CLOUDY FOR MUCH OF THE NIGHT HOWEVER. WITH THE LOW REMAINING TO OUR NORTHEAST, THE PRESSURE GRADIENT WILL REMAIN ACROSS THE AREA, KEEPING A STEADY BREEZE FOR MUCH OF THE NIGHT. HOWEVER, WE STILL EXPECT COLD TEMPERATURES TONIGHT AS COLD AIR ADVECTION WILL CONTINUE THROUGH THE NIGHT. WE`VE ISSUED A FREEZE WARNING FOR AREAS WHERE WE ARE MOST CONFIDENT OF SUB- FREEZING TEMPERATURES OCCURRING OVERNIGHT, AND A FREEZE WATCH FOR THOSE AREAS WHERE WE ARE A LITTLE MORE UNCERTAIN. WITH THE BREEZE EXPECTED, IT MAY BE HARD TO DEVELOP MUCH FROST, SO THAT`S WHY WE HAVEN`T INCLUDED FRONT IS THE FORECAST OR ISSUED A FROST ADVISORY AT THIS TIME.
-- End Changed Discussion --
&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
THE WRF-NMM INITIALIZATION LOOKED SLIGHTLY BETTER THAN THE GFS AT 500MB IN THE EASTERN CONUS AND THE REVERSE IN THE WESTERN CONUS. THE NAM/WRF-NMMB INITIALIZATION AT 925MB AND 850MB LOOKED SLIGHTLY BETTER. THE CORE OF THIS CHILLY AIR MASS WAS SLIGHTLY COLDER THAN INITIALIZED. THE LONG TERM MODEL GUIDANCE HAS HAD LATITUDINAL FLIPPING OF SYSTEMS AND TONIGHT WAS NO DIFFERENT. WHILE THERE HAS BEEN SOME SETTLING OF FEATURES FOR SATURDAY AND SUNDAY, THE POTENTIAL NOR`EASTER AT THE END OF THE LONG TERM NOW FINDS THE GFS AS THE MOST AGGRESSIVE MODEL WITH THE OP ECMWF SUPPRESSED BEYOND BELIEF. THE DIFFERENCE IS NOT A SLOWER EXIT OR MORE INTENSE SATURDAY SYSTEM, BUT A DE-AMPLIFICATION OF THE FLOW ACROSS CENTRAL AND WESTERN NOAM. WOULD BE SHOCKED IF THE ECMWF ENSEMBLE MEAN IS NOT MORE AMPLIFIED. CONVERSELY, THE 00Z OPERATIONAL GFS WAS ALONG THE NW OR NRN FRINGE OF GEFS MEMBERS WITH BOTH THE SATURDAY AND END OF LONG TERM SYSTEM. STAY TUNED. NO BACKING AWAY FROM A CHILLY/FROSTY START TO THE LONG TERM. ON FRIDAY, A CHANNELIZED VORT MAX WILL BE MOVING NEWD AND LIFTING TOWARD THE NERN EDGE OF OUR CWA. WHILE CONVECTIVE TEMPS ARE PREDICTED TO BE REACHED, THERE IS LESS CERTAINTY THAN TODAY, ESPECIALLY THE SWRN HALF OF OUR CWA. SO AN OVERALL SUNNIER DAY IS EXPECTED. MAX TEMPS ARE TOWARD THE HIGH END OF STAT GUIDANCE AND IF YESTERDAY WAS ANY INDICATION, MAYBE NOT HIGH ENOUGH. WINDS ARE STILL EXPECTED TO BE BRISK AND THIS IS A FIRE WEATHER CONCERN GIVEN LOW RELATIVE HUMIDITY LEVELS PREDICTED. PLEASE SEE FIRE WEATHER SECTION BELOW. FOR FRIDAY NIGHT WE HAVE ISSUED A FREEZE WATCH FOR MOST OF OUR PA AND NJ ZONES WHERE THE GROWING SEASON HAS STARTED. EXCEPTION IMMEDIATE COAST AND PHL AREA. WE ARE NOT AS SURE ABOUT DELMARVA. SFC HIGH PRESSURE SHOULD BE CLOSE ENOUGH TO DECOUPLE WINDS. ANOTHER SIGNAL IS THE WAA PREDICTED ABOVE THE BOUNDARY LAYER. BECAUSE WINDS WILL BE LIGHTER, WE HAVE INCLUDED FROST IN THE GRIDS. STAT GUIDANCE IS PRETTY CLOSE AND WE FOLLOWED THEM FOR MINS. LOOKING AT THE GFS DIAGS FOR SATURDAY AND SATURDAY NIGHT, OTHER THAN MID LEVEL QVEC CONVERGENCE, MOST OTHER PREDICTED FORCING (MID LEVEL WAA, 300K ISENTROPIC LIFT. LOCATION OF THE 250MB JET) MECHANISMS SUGGEST THE MODEL IS TOO FAR NORTH WITH ITS QPF. ERGO WE ARE REMAINING PRETTY CLOSE TO CONTINUITY WITH A SHARP CUT-OFF OF POPS NEAR THE MASON-DIXON LINE. IRONICALLY AGAIN GFS MOS IS WARMER THAN NAM MOS WITH MAX TEMPS ON SATURDAY IN SPITE OF BEING FASTER AND FARTHER NORTH WITH THE CLOUDS AND PCPN. DEFINITE UPSIDE POTENTIAL OVER STAT GUIDANCE FOR MAX TEMPS SATURDAY AND WE WERE NEAR THEM SOUTH AND ALONG THEN COAST, BUT OVERALL WARMER ELSEWHERE. CONSENSUS IS FOR GREATEST PCPN CHANCES ON SATURDAY NIGHT AND AN EXIT OF PCPN BY SUNDAY MORNING BY ALL OF THE MODELS. THE CURRENT CLOSED LOW OVER ONTARIO THAT IS GOING TO HELP STEER THE WEEKEND SFC SYSTEM WELL TO OUR SOUTH IS PREDICTED TO RETROGRADE WWD AT THE LEAST INTO NEW ENGLAND ON SUNDAY AND THEN LINGER CLOSE BY ON MONDAY AND TUESDAY. SOME INSTABILITY SHOWERS ARE POSSIBLE UNDER THIS COLD POOL. BUT THE THERMAL PROFILE CLOSER TO THE SURFACE WILL BE MILDER. SO WHILE TEMPS SHOULD STILL BE BELOW NORMAL, THEY SHOULD BE A CATEGORY OR TWO HIGHER THAN TODAY AND FRIDAY. WE LEFT IN THE CHANCE FOR RAIN ON WEDNESDAY ASSOCIATED WITH THE NEXT LOW PRESSURE SYSTEM/POSSIBLE NOR`EASTER. NOT THAT WE EXPECTED CONSENSUS AT THIS JUNCTURE, BUT THE SPREAD IN TRACK (AND TIMING ALSO) SOLUTIONS HAS INCREASED FROM LAST NIGHT.
-- End Changed Discussion --
&& .AVIATION /08Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR CONDITIONS WILL PREVAIL ACROSS THE TAF SITES THROUGH THE PERIOD, ALTHOUGH CLOUD COVER WILL INCREASE THROUGH DAY AND INTO TONIGHT. WINDS WILL BE THE MAIN CONCERN AS WINDS GUSTS WILL INCREASE THROUGH THE DAY AND WILL GUST 25-30 KNOTS AT TIMES TODAY. THE SPEED OF THE GUSTS MAY DROP OFF A BIT THIS EVENING AND OVERNIGHT, BUT WE COULD STILL GET SOME GUSTS ROUND 20 KNOTS THROUGH THE NIGHT FOR MANY AREAS. OUTLOOK... FRIDAY...CONTINUED VFR CONDITIONS, WITH GUSTY WEST-NORTHWEST WINDS TO AROUND 25 KNOTS, ESPECIALLY LATE MORNING AND THROUGH THE AFTERNOON. FRIDAY NIGHT...VFR CONDITIONS WITH LIGHTER WINDS. SATURDAY AND SATURDAY NIGHT...MAINLY VFR CONDITIONS NORTHERN AIRPORTS AND TERMINALS. SOME RAIN AND SUB-VFR CONDITIONS ARE POSSIBLE, MAINLY SOUTH OF A KILG/KACY LINE. SUNDAY THROUGH MONDAY...MAINLY VFR CONDITIONS ARE EXPECTED.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR TODAY AND TONIGHT AS WINDS WILL REMAIN ELEVATED WITH THE PRESSURE GRADIENT REMAINING ACROSS THE AREA AND SOME WINDS FROM ALOFT MIXING DOWN TO THE SURFACE. WITH THE NORTHWEST FLOW, SEAS ARE NOT EXPECTED TO BUILD SIGNIFICANTLY AND SHOULD BE AROUND 4-5 FEET. OUTLOOK... FRIDAY AND FRIDAY NIGHT...THE SMALL CRAFT ADVISORY WAS EXTENDED THROUGH THE DAY FRIDAY ALL WATERS AND MIGHT NEED AN EXTENSION INTO FRIDAY NIGHT, OR AT LEAST FRIDAY EVENING. SATURDAY THROUGH SUNDAY...SUB SMALL CRAFT ADVISORY CONDITIONS EXPECTED. THE LOW PRESSURE SYSTEM SHOULD PASS TOO FAR TO THE SOUTH TO GENERATE HIGHER SEAS OR WINDS. SUNDAY NIGHT THROUGH MONDAY...CONTINUED SUB-SCA CONDITIONS; ALTHOUGH, SOME WIND GUSTS TO AROUND 20 KNOTS PLUS ARE POSSIBLE.
-- End Changed Discussion --
&& .FIRE WEATHER...
-- Changed Discussion --
DRY AND GUSTY CONDITIONS ARE EXPECTED TODAY WITH RH VALUES EXPECTED TO DIP INTO THE MID/UPPER 20S AND WINDS GUSTING AROUND 25-30 MPH. THE QUESTION IS HOW MOIST THE FUELS ARE DO TO THE RECENT RAINFALL THE LAST FEW DAYS. WE WILL LET THE DAY SHIFT CONTACT STATE PARTNERS TO ASCERTAIN FUEL MOISTURE CONDITIONS FOR TODAY AND SEE IF ANY FIRE WEATHER PRODUCTS ARE NEEDED. CONDITIONS MAY BE ENHANCED ON FRIDAY FOR THE POTENTIAL OF WILDFIRE SPREAD ACROSS THE REGION. FRIDAY`S RELATIVE HUMIDITY VALUES ARE PROGGED TO DROP BELOW 30 PERCENT FOR A TIME FROM LATE FRIDAY MORNING AND THROUGH THE AFTERNOON TO EARLY EVENING. IN ADDITION, SUSTAINED WEST-NORTHWEST WINDS BETWEEN 15 TO 20 MPH ARE FORECAST DURING THIS TIMEFRAME, WITH GUSTS REACHING BETWEEN 25 TO 30 MPH AT TIMES. WE WILL CONTINUE TO MONITOR THE LATEST GUIDANCE AND COORDINATE WITH OUR FIRE WEATHER PARTNERS IF ANY ADDITIONAL PRODUCTS BECOME NECESSARY.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR PAZ060>062-101>106. FREEZE WARNING FROM 2 AM TO 9 AM EDT FRIDAY FOR PAZ061-062-105. FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR PAZ060-101>104-106. NJ...FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR NJZ001-007>010-012-013-015>022-027. FREEZE WARNING FROM 2 AM TO 9 AM EDT FRIDAY FOR NJZ001-007>010. FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR NJZ012-013-015>022-027. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ430-431- 450>455.
-- End Changed Discussion --
&& $$ SYNOPSIS...GIGI/KLINE NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...GIGI AVIATION...GIGI/KLINE/ROBERTSON MARINE...GIGI/KLINE/ROBERTSON FIRE WEATHER...ROBERTSON/GIGI

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