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 280814 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 414 AM EDT TUE OCT 28 2014 .SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE WILL REMAIN OFFSHORE TODAY. A COLD FRONT APPROACHES THE AREA OVERNIGHT AND MOVES THROUGH WEDNESDAY. HIGH PRESSURE WILL BRIEFLY BUILD IN FOR THURSDAY BEFORE AN AREA OF LOW PRESSURE MOVES OUT OF THE GREAT LAKES REGION AND COMBINES WITH A DEVELOPING COASTAL LOW OFFSHORE OF THE MID ATLANTIC. HIGH PRESSURE RETURNS FOR THE END OF THE WEEKEND AND EARLY NEXT WEEK.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
HIGH PRESSURE HAS MOVED OFF THE SOUTHEAST AND MID-ATLANTIC COAST EARLY THIS MORNING. MEANWHILE, A 998 MB SFC LOW WAS LOCATED NEAR LAKE MICHIGAN WITH A COLD FRONT EXTENDING SOUTHWESTWARD ACROSS THE MIDWEST AND SOUTHERN PLAINS. THE MID-ATLANTIC REGION IS LOCATED UNDERNEATH DEEP WESTERLY FLOW ALOFT ATOP THE RIDGE. DUE TO THE DEVELOPMENT OF A STRONG NOCTURNAL INVERSION, THERE WASN`T MUCH EVIDENCE OF A WARM FRONT EAST OF THE APPALACHIANS ON THE LATEST SFC ANALYSIS DESPITE THE SIGNIFICANT WAA ALOFT. SFC TEMPS OVERNIGHT VARY CONSIDERABLY FROM LOCATION TO LOCATION, RANGING FROM THE UPPER 30S/LOWER 40S WHERE WINDS HAVE DECOUPLED AND RADIATIONAL COOLING WAS HIGHLY EFFECTIVE TO THE 50S WHERE THERE WAS STILL A LIGHT SOUTHERLY WIND. HIGH CLOUDS AROUND THE PERIPHERY OF THE RIDGE ARE STREAMING IN FROM THE WEST EARLY THIS MORNING BUT THESE CLOUDS ARE EXPECTED TO THIN OUT OVER THE MID-ATLANTIC REGION LATER THIS MORNING AS THE BULK OF THE UPPER-LEVEL MOISTURE SHIFTS DOWNSTREAM INTO THE NORTHEAST. AHEAD OF THE MIDWEST COLD FRONT, THE CORE OF THE WARM SECTOR WILL BECOME ESTABLISHED OVER MID-ATLANTIC STATES THIS AFTERNOON. MAJORITY OF MODEL GUIDANCE SHOWS 925 MB AND 850 MB TEMPS FOR PHL INCREASING TO AROUND 21C AND 17C RESPECTIVELY, WHICH IS A +2 SD OCCURRENCE FOR LATE OCTOBER. ASSUMING FULL MIXING DOWN FROM THE 925 MB WARM NOSE, TEMPS WOULD REACH THE LOWER TO MID 80S. MAX TEMP FORECAST IS NOT QUITE THAT WARM (SINCE FULL MIXING NOT EXPECTED OWING TO THE LOW SUN ANGLE) BUT IS SEVERAL DEGREES ABOVE STAT GUIDANCE. FORECAST HIGHS IN LOW 80S IN THE DELMARVA AND MID TO UPPER 70S ELSEWHERE MATCHES UP WELL WITH UPSTREAM OBSERVATIONS YESTERDAY IN THE MIDWEST.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
-- Changed Discussion --
LOW PRESSURE WILL CONTINUE TO LIFT NORTH OF THE GREAT LAKES TONIGHT AND TOWARDS JAMES BAY. THE COLD FRONT WITH THIS SYSTEM IS EXPECTED TO CROSS THE APPALACHIANS THIS EVENING AND SHOULD BE ON THE FRONT DOOR STEP OF OUR FAR WESTERN ZONES IN EASTERN PA BY DAYBREAK. THE TREND OF RECENT GUIDANCE WAS TO SLOW DOWN THE PROGRESSION OF THE FRONT EVER SO SLIGHTLY. FOLLOWED THIS TREND WITH POPS OVERNIGHT, KEEPING ANY MENTION OF SHOWERS WEST OF THE FALL LINE. POPS FOLLOW CLOSE SUITE TO THE 21Z/03Z SREF RUNS. WENT ABOVE MOS GUIDANCE FOR MIN TEMP AS SOUTHWESTERLY FLOW IN PRE-FRONTAL WARM SECTOR AND INCREASING CLOUD COVER LATE SHOULD LIMIT RADIATIONAL COOLING.
-- End Changed Discussion --
&& .LONG TERM /WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
A COLD FRONT WILL BE MOVING INTO THE AREA AT THE BEGINNING OF THE DAY WEDNESDAY AND PROGRESS ITS WAY THROUGH THE AREA DURING THE DAY AND INTO THE EVENING. POPS WILL INCREASE FROM WEST TO EAST THROUGH THE DAY AS THE FRONT MOVES THROUGH. MODEL GUIDANCE IS IN PRETTY GOOD AGREEMENT WITH THE PRECIP OCCURRING MOSTLY FROM LATE MORNING THROUGH THE AFTERNOON HOURS. THERE IS SOME DIFFERENCES IN QPF AMOUNTS, BUT OVERALL DOES NOT LOOK LIKE A SIGNIFICANT AMOUNT OF RAIN, GENERALLY ONE-TENTH TO ONE-QUARTER OF AN INCH OR LESS. THE FRONT MOVES OFFSHORE BY LATE IN THE DAY, AND THE MAIN SHORT WAVE MOVES THROUGH OVERNIGHT. PRECIP CHANCES WILL DIMINISH FROM WEST TO EAST THROUGH THE LATE AFTERNOON AND EVENING, AND SHOULD BE ALL OUT OF THE AREA BY OR SHORTLY AFTER MIDNIGHT. HIGH PRESSURE IS EXPECTED TO BRIEFLY AFFECT THE AREA THURSDAY INTO THURSDAY NIGHT. DRY WEATHER AND NEAR NORMAL TEMPERATURES ARE EXPECTED BEFORE A CHANGE FOR THE UPCOMING WEEKEND. ON FRIDAY, AND AREA OF LOW PRESSURE WILL BE MOVING OUT OF THE GREAT LAKES REGION, AND APPROACHING THE AREA, WHILE A COASTAL LOW DEVELOPS AND STRENGTHENS TO OUR SOUTHEAST. WE DO NOT EXPECT ANY PRECIPITATION DURING THE DAY AS THE PRECIPITATION TIED TO THE APPROACHING LOW TO THE NORTHWEST SHOULD STILL BE TO OUR NORTHWEST. HOWEVER, AS WE GO INTO SATURDAY NIGHT, THE LOW TO THE NORTHWEST IS EXPECTED TO BEGIN GETTING ABSORBED BY THE COASTAL LOW. AT THE SAME TIME, THE MID/UPPER TROUGH WILL BE DIVING SOUTHWARD INTO THE AREA AS WELL. THIS WILL ALLOW PRECIPITATION TO FILL IN ACROSS THE AREA. THE MID/UPPER TROUGH WILL SLOWLY SWING ACROSS THE AREA THROUGH SATURDAY, SO THERE COULD STILL BE SHOWERS ACROSS THE AREA THROUGH THE DAY SATURDAY. THERE IS SOME COLD AIR ASSOCIATED WITH THE MID/UPPER TROUGH SWINGING ACROSS THE AREA WITH SUB-ZERO 925/850MB TEMPERATURES LATE FRIDAY NIGHT THROUGH SATURDAY INTO SATURDAY NIGHT. THERE IS THE POTENTIAL FOR SOME SNOW TO MIX WITH RAIN, OR EVEN A COMPLETE CHANCE OVER ACROSS THE HIGHER ELEVATIONS. WINDS WILL ALSO INCREASE SATURDAY INTO SATURDAY NIGHT AS THE PRESSURE GRADIENT TIGHTENS SIGNIFICANTLY BETWEEN THE COASTAL LOW AND HIGH PRESSURE TO THE WEST. IMPROVING CONDITIONS ARE EXPECTED FOR SUNDAY INTO MONDAY AS HIGH PRESSURE IS EXPECTED TO BUILD INTO THE REGION FROM THE WEST. THE 00Z ECMWF IS SLOWER TO MOVE THE COASTAL LOW TO THE NORTHWEST, BUT THE THOUGHT IS THIS MAY BE TO SLOW.
-- End Changed Discussion --
&& .AVIATION /07Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. VFR TODAY AND TONIGHT WITH MAINLY HIGH CLOUDS EXPECTED. CLOUDS WILL INCREASE AND CIGS WILL START TO LOWER IN VC OF RDG/ABE AFTER 06Z WEDNESDAY. LIGHT AND VARIABLE WINDS EARLY THIS MORNING. S-SW WINDS 5-10 KT THIS AFTERNOON AND TONIGHT. CONSIDERED INCLUDING LLWS FOR THE 00Z-12Z WEDNESDAY PERIOD WITH A 40-45 KT LLVL JET BUT SHEAR VALUES NOT QUITE REACHING THRESHOLD FOR THE TAFS. WEDNESDAY...SCATTERED SHOWERS POSSIBLE WHICH MAY PERIODICALLY REDUCE CIGS/VSBYS. WEDNESDAY NIGHT-FRIDAY...MOSTLY VFR. FRIDAY NIGHT-SATURDAY...GENERALLY VFR, WITH MVFR CONDITIONS POSSIBLE WITH SHOWERS. SNOW SHOWERS POSSIBLE ACROSS NORTHEAST PENNSYLVANIA AND NORTHWEST NEW JERSEY. STRONG, GUST WINDS SATURDAY INTO SATURDAY NIGHT.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SWLY WINDS WILL STRENGTHEN TODAY TO 10-20 KT. THE GRADIENT TIGHTENS A BIT MORE TONIGHT. WARM AIR ATOP THE COOLER OCEAN WATERS DO NOT PROVIDE A PARTICULARLY FAVORABLE MIXING SETUP BUT OCCASIONAL GUSTS TO 25 KT ARE POSSIBLE OVER THE COASTAL WATERS LATE. USING WAVEWATCH GUIDANCE, SEAS WILL INCREASE TO 4-5 FT OVERNIGHT. A SCA WAS ISSUED FOR THE ATLANTIC ZONES STARTING AT MIDNIGHT TONIGHT. WEDNESDAY...SMALL CRAFT REMAINS IN EFFECT THROUGH MIDDAY WEDNESDAY, THEN SEAS ARE EXPECTED TO SUBSIDE. WEDNESDAY NIGHT-FRIDAY...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED. FRIDAY NIGHT-SATURDAY...INCREASING WINDS OVERNIGHT INTO SATURDAY AND SATURDAY NIGHT AS A COASTAL LOW STRENGTHENS. AT LEAST SMALL CRAFT CONDITIONS EXPECTED, WITH GALE FORCE WINDS POSSIBLE.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...ROBERTSON NEAR TERM...KLEIN SHORT TERM...KLEIN LONG TERM...ROBERTSON AVIATION...KLEIN/ROBERTSON MARINE...KLEIN/ROBERTSON

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