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. --
902 FXUS61 KPHI 040920 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 420 AM EST THU FEB 4 2016 .SYNOPSIS...
-- Changed Discussion --
A COLD FRONT WILL PUSH EAST OF THE MID-ATLANTIC EARLY TODAY BUT REMAIN NEARBY OFFSHORE INTO TONIGHT. AN AREA OF LOW PRESSURE IS THEN FORECAST TO DEVELOP ALONG THE OFFSHORE FRONT LATE TONIGHT AND MOVE OUT TO SEA FRIDAY. HIGH PRESSURE WILL GRADUALLY BUILD INTO OUR AREA FROM THE SOUTHWEST LATE FRIDAY AND SATURDAY. A WEAK COLD FRONT FROM THE NORTHWEST MAY CROSS THE AREA EARLY SUNDAY, FOLLOWED BY A LOW PRESSURE SYSTEM POSSIBLY AFFECTING THE REGION EARLY NEXT WEEK.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
A COLD FRONT OVER E PA AT 3 AM WILL MOVE EASTWARD THRU THE I-95 CORRIDOR THRU DAYBREAK AND THEN OFF THE NJ/DE COAST BY MID MORNING. DENSE FOG HAS PERSISTED THRU MUCH OF THE OVERNIGHT ALONG AND WEST OF THE FALL LINE WHERE THERE IS STILL RESIDUAL (ALBEIT MINIMAL) SNOW COVER. THE DENSE FOG ADVISORY FOR E PA, C/NW NJ, AND E MD REMAINS IN EFFECT THRU 7 AM BUT WE MAY BE ABLE TO CANCEL IT EARLY AS THE PUSH OF DRY AIR BEHIND THE FRONT ERODES THE FOG FROM WEST TO EAST. THE BACK EDGE OF THE STEADY RAIN IN THE WARM SECTOR HAD MOVED OFFSHORE LAST EVENING BUT THERE ARE STILL SOME SHOWERS ALONG AND AHEAD OF THE FRONT THAT WILL PRIMARILY IMPACT THE COASTAL PLAIN EARLY THIS MORNING. THERE WILL LIKELY BE A BREAK IN PRECIP FROM LATE THIS MORNING THRU THE AFTERNOON ALTHOUGH A COUPLE OF SHOWERS CANNOT BE COMPLETELY RULED OUT NEAR THE COAST WITH THE FRONTAL BOUNDARY STALLING OFFSHORE. THE REGION WILL START OFF CLOUDY THIS MORNING BUT THERE WILL BE BREAKS IN OUR FAR NW ZONES TODAY ONCE THE FOG/STRATUS ERODES. WITH THE UPPER TROUGH STILL BACK TO OUR WEST, THE MID AND HIGH CLOUDS WILL YIELD MOSTLY CLOUDY SKIES ALONG AND ESPECIALLY EAST OF I-95. DESPITE THE CLOUD COVER, WENT ABOVE STAT GUIDANCE FOR TEMPS TODAY WITH THE GUIDANCE CONTINUALLY BEING BIASED TOO COLD FOR HIGHS OVER THE PAST WEEK AND HALF. THE HIGHS MAY OCCUR EARLIER THAN USUAL SOMETIME THIS MORNING AS POST-FRONTAL CAA IS STRONG ENOUGH TO OFFSET THE DAYTIME HEATING.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
-- Changed Discussion --
SHORTWAVE ENERGY ASSOCIATED WITH THE UPPER TROUGH WILL PROGRESS TOWARD THE EASTERN SEABOARD TONIGHT. THE MODELS CONTINUE TO SHOW SECONDARY CYCLOGENESIS ALONG THE SOUTHEAST COAST BY EARLY THIS EVENING. THE SURFACE LOW IS EXPECTED TO DEEPEN AS IT MOVES TO THE NE ALONG THE STALLED FRONTAL BOUNDARY. THE TRACK OF THE LOW IS FORECAST TO BE FAR ENOUGH OFFSHORE TO SPARE OUR AREA FROM THE GREATEST IMPACTS (I.E., HEAVY PRECIP AND STRONG WINDS) BUT WE WON`T BE COMPLETELY MISSED. THE MODEL GUIDANCE HAS COME INTO VERY GOOD AGREEMENT WITH RESPECT TO THE EVOLUTION OF THERMAL PROFILES, THE TIMING OF PRECIP AND THE PLACEMENT OF THE PRECIP SHIELD. WE CAN SAY WITH REASONABLE CONFIDENCE THAT PRECIP SHOULD EXPAND NEWD INTO THE DELMARVA AND COASTAL NJ THIS EVENING. THE WESTERN EDGE OF THE PRECIP SHIELD WILL LIKELY SET UP SOMEWHERE NEAR THE I-95 CORRIDOR OVERNIGHT. THE THERMAL PROFILES WILL INITIALLY BE WARM ENOUGH FOR RAIN EVERYWHERE IN THE EVENING. HOWEVER, HIGH PRESSURE BUILDS IN FROM THE WEST AND NW WINDS WILL ADVECT COLDER AIR INTO THE AREA OVERNIGHT. THUS, WE EXPECT THE RAIN TO MIX WITH AND EVENTUALLY CHANGE OVER TO SNOW FROM WEST TO EAST OVERNIGHT. THERE IS STILL UNCERTAINTY REGARDING HOW MUCH OF THIS WILL FALL AS RAIN VS SNOW AND HOW MUCH OF THE SNOW WILL BE ABLE TO ACCUMULATE WITH MARGINAL BOUNDARY LAYER TEMPERATURES. THE WILD CARD WILL BE DYNAMICAL COOLING. THE GUIDANCE HAS TRENDED A LITTLE BIT HIGHER WITH THE QPF FOR THE 06-12Z PERIOD WITH AROUND 0.5 INCH FORECAST ALONG THE COAST. WE TRENDED SLIGHTLY HIGHER WITH OUR FORECAST SNOWFALL AMOUNTS OF 1-2 INCHES IN THE LOWER DELMARVA AND SE NJ. HOWEVER, THERE IS STILL A REASONABLE WORST-CASE SCENARIO (I.E., 90TH PERCENTILE) THAT SOME LOCATIONS ESPECIALLY IN THE COASTAL PLAIN COULD GET DOUBLE THESE FORECAST AMOUNTS IF DYNAMICAL COOLING IS EVEN STRONGER THAN FORECAST AND PRECIP TRANSITIONS TO SNOW MUCH QUICKER. THE APPARENT UNCERTAINTY IS STILL TOO HIGH TO ISSUE ANY WINTER WEATHER ADVISORY THIS FAR OUT.
-- End Changed Discussion --
&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
AN OVERALL ACTIVE PATTERN LOOKS TO BE IN PLACE THROUGH THE LONG TERM PERIOD, ESPECIALLY FROM THE LATTER HALF OF THE WEEKEND AND INTO EARLY NEXT WEEK. FOR FRIDAY MORNING, AN AREA OF LOW PRESSURE IS FORECAST TO BE OFF OF THE MID-ATLANTIC COAST, EAST OF VIRGINIA, ALONG AN OLD COLD FRONTAL BOUNDARY. WHILE THIS LOW PRESSURE IS FORECAST TO TRACK NORTHEAST AND FARTHER OUT TO SEA THROUGH THE COURSE OF THE DAY, THE PROXIMITY OF THIS SYSTEM TO THE NEW JERSEY AND DELAWARE COASTS FRIDAY MORNING MAY ALLOW FOR SOME LINGERING LIGHT SNOW ACROSS EASTERN NJ AND SOUTHEAST DE BEFORE THE SYSTEM DEPARTS FARTHER EAST BY LATE MORNING TO MIDDAY. TOTAL ACCUMULATION AMOUNTS FOR THESE AREAS FROM LATE THURSDAY NIGHT THROUGH EARLY FRIDAY MAY REACH BETWEEN ONE TO TWO INCHES, BUT WITH SOME UNCERTAINTY REGARDING TRACK AND QPF AMOUNTS, WE WILL HOLD OFF ON ANY ADVISORY HEADLINES AT THIS TIME. OTHERWISE, THE REMAINDER OF FRIDAY SHOULD BE DRY WITH GRADUAL CLEARING FROM WEST TO EAST ACROSS THE REGION AS AN AREA OF HIGH PRESSURE TO OUR SOUTHWEST BUILDS TOWARD THE MID-ATLANTIC. THIS HIGH PRESSURE IS EXPECTED TO STICK AROUND THROUGH SATURDAY ACROSS THE AREA, YIELDING DRY AND QUIET CONDITIONS WITH JUST SOME CLOUDS ADVANCING IN FROM THE NORTHWEST AS THE DAY WEARS ON. DAYTIME MAXIMUM TEMPERATURES ARE EXPECTED TO BE PRETTY SIMILAR BOTH FRIDAY AND SATURDAY, MAINLY IN THE 40S ACROSS THE REGION, EXCEPT SOME TEMPS MAXING OUT IN THE 30S OVER THE HIGHER TERRAIN IN THE POCONOS. BY EARLY SUNDAY, A WEAK COLD FRONT MAY APPROACH OUR REGION FROM THE NORTHWEST, BUT WITH LIMITED MOISTURE ASSOCIATED WITH THIS BOUNDARY, WE HAVE KEPT A DRY FORECAST FOR SUNDAY, WITH DAYTIME HIGHS REACHING MAINLY IN THE 40S. OF NOTE, THE GFS AND ECMWF CONTINUE TO DEVELOP AN AREA OF LOW PRESSURE OF VARYING INTENSITY OFF THE SOUTHEASTERN SEABOARD SUNDAY, TAKING IT OUT TO SEA LATER SUNDAY NIGHT. LITTLE OR NO IMPACT IS STILL EXPECTED FOR OUR REGION, EXCEPT PERHAPS SOME INCREASING CLOUDINESS, ESPECIALLY OVER THE SOUTHERN HALF OF OUR CWA. THROUGH THE REMAINDER OF THE LONG TERM PERIOD, THERE CONTINUES TO BE SIGNIFICANT MODEL DIFFERENCES WITH REGARDS TO A POSSIBLE LOW PRESSURE SYSTEM PASSING ACROSS THE GREAT LAKES MONDAY AND ANOTHER AREA OF LOW PRESSURE POSSIBLY DEVELOPING OFF THE EAST COAST TUESDAY. WHILE THE TIMING OF PRECIPITATION ACROSS OUR REGION REMAINS A LOW CONFIDENCE FORECAST AT THIS TIME, THE OVERALL PATTERN AND A BROAD LONGWAVE TROUGH OVER THE GREAT LAKES TO NORTHEAST AND MID-ATLANTIC SUGGESTS A COLDER TREND INTO EARLY/MID NEXT WEEK, AND WE GENERALLY FOLLOWED SUPERBLEND AND/OR WPC GUIDANCE WITH REGARDS TO TEMPS AND POPS AT THIS EXTENDED TIME RANGE.
-- End Changed Discussion --
&& .AVIATION /09Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. RAIN HAS MOSTLY MOVED EAST OF THE TAF SITES (WITH THE EXCEPTION OF ACY WHICH MAY CONTINUE TO SEE A SHOWER OR TWO OVER THE NEXT FEW HOURS), HOWEVER FOG HAS BEGUN TO DEVELOP OVER WESTERN PORTIONS OF THE REGION INCLUDING KRDG AND KABE. EXPECT THIS FOG TO PERSIST UNTIL THE COLD FRONT ARRIVES SOMETIME BEFORE 12Z. NOT SURE HOW DENSE THE FOG WILL BE OVER THE DELAWARE VALLEY (INCLUDING KPHL, KPNE, KILG, AND KTTN) AND COASTAL PLAIN SITES (INCLUDING KMIV AND KACY) ONCE IT DEVELOPS, SO FOR NOW HAVE GONE OPTIMISTICALLY, THOUGH IT IS POSSIBLE VISIBILITIES COULD FALL BELOW 1 MILE. CONDITIONS SHOULD RAPIDLY IMPROVE TO VFR BEHIND THE COLD FRONT, AND SHOULD STAY VFR THROUGH THE DAY TOMORROW. WIND DIRECTION HAS BEEN VARIABLE OVER THE LAST FEW HOURS, BUT SHOULD GENERALLY BE SOUTHWESTERLY UNTIL THE FRONT ARRIVES WHEN AN ABRUPT SHIFT TO NORTHWESTERLY IS EXPECTED. OUTLOOK... FRIDAY...MAINLY VFR, EXCEPT POSSIBLE SUB-VFR IN LIGHT SNOW IN THE MORNING FOR EASTERN SITES, ESPECIALLY KACY/KMIV. SATURDAY AND SUNDAY...MAINLY VFR CONDITIONS ARE EXPECTED. MONDAY...MAINLY VFR, BUT CONDITIONS MAY LOWER AS THE DAY WEARS ON DUE TO POSSIBLE LOW PRESSURE APPROACHING THE REGION. IN ADDITION TO POSSIBLE LOWER CIGS DEVELOPING, LOWER VSBYS MAY ALSO OCCUR IN RAIN/SNOW.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SCA ON THE BAY HAS BEEN EXTENDED THROUGH 12Z AS A FEW GUSTS ABOVE 25KT BOTH AHEAD OF AND WITH THE COLD FRONT WHICH SHOULD ARRIVE BEFORE 12Z. ON THE OCEAN WATERS, EXPECT SCA CONDITIONS TO CONTINUE THROUGH THE DAY TOMORROW, THOUGH WINDS AND SEAS SHOULD BE SLOWLY SUBSIDING AFTER SUNRISE. OUTLOOK... FRIDAY...BREEZY NORTHWEST WINDS ARE EXPECTED, AND GUSTS BETWEEN 25 TO 30 KNOTS ARE EXPECTED FOR THE ATLANTIC COASTAL WATERS. WE HAVE EXTENDED THE SCA THROUGH 6PM FRIDAY. SATURDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED. SUNDAY AND MONDAY...WINDS AND SEAS LOOK TO REMAIN BELOW ADVISORY CRITERIA FOR MUCH OF SUNDAY, BUT THERE IS SOME POTENTIAL FOR OFFSHORE LOW PRESSURE TO PASS EAST OF OUR WATERS SUNDAY NIGHT INTO MONDAY, WHICH COULD ENHANCE SEAS AND WIND GUSTS.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR PAZ054-055- 060>062-101>106. NJ...DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR NJZ007>010- 015. DE...NONE. MD...DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR MDZ008-012- 015-019-020. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ450>455.
-- End Changed Discussion --
&& $$ SYNOPSIS...KLINE NEAR TERM...KLEIN SHORT TERM...KLEIN LONG TERM...KLINE AVIATION...KLEIN/KLINE MARINE...KLEIN/KLINE

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