493
FXUS61 KPHI 180925
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
525 AM EDT THU OCT 18 2018
SYNOPSIS
HIGH PRESSURE WILL BUILD FROM THE OHIO VALLEY INTO THE MIDDLE
ATLANTIC REGION THROUGH FRIDAY NIGHT. LOW PRESSURE WILL THEN TRACK
TO OUR NORTH OVER SOUTHERN CANADA DRAGGING A COLD FRONT ACROSS OUR
REGION SATURDAY. HIGH PRESSURE WILL THEN BUILD INTO THE AREA INTO
THE START OF NEXT WEEK.
NEAR TERM /UNTIL 6 PM THIS EVENING/
TEMPERATURES IN THE POCONOS AND NW NJ HAVE INCREASED SLIGHTLY
OVER THE PAST 2 HOURS. THEREFORE, CANCELLED THE FREEZE WARNING
FOR THIS MORNING AS ALL SITES ARE ABOVE FREEZING. THE FREEZE
WARNING FOR TONIGHT/FRIDAY MORNING REMAINS IN EFFECT.
SURFACE HIGH WILL CONTINUE TO BUILD TOWARDS THE REGION THROUGH THE
DAY TODAY. IN THE MID AND UPPER LEVELS, THE TROUGH WILL SHIFT
FURTHER OFF SHORE WITH HEIGHTS BEGINNING TO GRADUALLY BUILD OVER OUR
REGION THROUGH THE DAY.
THE PRESSURE GRADIENT IS EXPECTED TO GRADUALLY DIMINISH, ESPECIALLY
THIS AFTERNOON. THEREFORE, NOT EXPECTING AS BREEZY OF A DAY
YESTERDAY. HOWEVER, TEMPERATURE WISE, THIS COULD BE THE COLDEST DAY
OF THE SEASON SO FAR WITH HIGHS ONLY IN THE 40S AND 50S ACROSS THE
REGION.
SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/
WE SHOULD HAVE ALL THE INGREDIENTS NEEDED TONIGHT FOR A WIDESPREAD
FREEZE AND FROST FOR MUCH OF THE AREA OVERNIGHT. SURFACE HIGH WILL
CONTINUE TO BUILD CLOSER. WINDS SHOULD BE LIGHT AND SKIES SHOULD BE
CLEAR. CONSEQUENTLY HAVE ISSUED A FREEZE WARNING FOR EAST CENTRAL PA
AND NW NJ.
FOR BERKS, WESTERN CHESTER, AND UPPER MONTGOMERY COUNTIES, HAVE GONE
WITH A FROST ADVISORY FOR NOW, THOUGH WOULD NOT BE SURPRISED IF THE
HIGHER ELEVATIONS, ESPECIALLY IN BERKS COUNTY ARE ABLE TO GET TO
FREEZING.
THE OTHER LOCATION OF CONCERN IS THE PINE BARRENS OF SOUTH JERSEY.
GUIDANCE CONSISTENTLY HAS A WARM BIAS IN SCENARIOS LIKE THIS, SO I
HAVE UNDERCUT GUIDANCE MINS IN THESE LOCATIONS. EXPECT A WIDESPREAD
FROST, THOUGH AT THIS POINT, I THINK TEMPERATURES MAY STAY JUST
ABOVE FREEZING, SO WILL GO WITH A FROST ADVISORY.
THE URBAN CORRIDOR FROM WILMINGTON TO TRENTON SHOULD STAY IN THE
UPPER 30S THANKS IN LARGE PART TO THE URBAN HEAT ISLAND EFFECT, SO
NOT EXPECTING A WIDESPREAD FROST HERE (THOUGH LOCATIONS IN MERCER
COUNTY OUTSIDE OF TRENTON WILL LIKELY SEE FROST).
FOR DELMARVA, PATCHY FROST IS POSSIBLE IN INTERIOR SECTIONS, BUT NOT
SURE IT WILL BE WIDESPREAD, SO WILL HOLD OFF ON ISSUING A FROST
ADVISORY FOR THESE LOCATIONS.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
FRIDAY...INCREASING CLOUDS WITH SLIGHTLY BELOW NORMAL
TEMPERATURES. HIGH PRESSURE WILL BE MOVING OFFSHORE AND AN
APPROACHING LOW/FRONT WILL BRING ADDED MOISTURE TO WRN AREAS BY
LATE IN THE DAY.
FRIDAY NIGHT/SATURDAY...LOW PRESSURE MOVES NORTH OF THE AREA
WHILE AN ASSOCIATED FRONT CROSSES THE AREA. MOSTLY HIGH CHC /LOW
LIKELY POPS FOR THE PERIOD. TEMPERATURES A LITTLE ABOVE NORMAL,
PRIOR TO FROPA.
SATURDAY NIGHT THRU WEDNESDAY...HIGH PRESSURE ACROSS THE AREA
MUCH OF THE TIME SO MOSTLY FAIR WEATHER EXPECTED. A FEW SHOWERS
POSSIBLE N/NW TUE. TEMPERATURES WELL BELOW NORMAL SUN/MON, THEN
CLOSER TO NORMAL TUE. MUCH TO BELOW NORMAL WED.
NORMALS: MPO/PHL/GED -- HIGHS: 55/63/65 LOWS: 34/46/43 .
AVIATION /10Z THURSDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...VFR CONDITIONS EXPECTED. NORTHWESTERLY WINDS MAY AT TIMES
GUST TO NEAR 20 KT, BUT SHOULD GRADUALLY DIMINISH THROUGH THE DAY.
HIGH CONFIDENCE.
TONIGHT...VFR CONDITIONS EXPECTED. LIGHT NORTHWESTERLY WINDS WILL
SHIFT TO SOUTHWESTERLY OVERNIGHT. HIGH CONFIDENCE.
OUTLOOK...
FRIDAY...VFR EXPECTED WITH INCREASING CLOUDS.
FRI NIGHT/SATURDAY...SUB-VFR POSSIBLE WITH SCATTERED SHOWERS.
SAT NIGHT THRU MONDAY...VFR. GUSTY WINDS SUNDAY.
MARINE
WINDS WILL CONTINUE TO GRADUALLY DIMINISH THROUGH THE DAY. THE ONLY
SITE STILL REACHING GALE GUSTS IS AT BRANDYWINE SHOAL, SO WILL
KEEP THE GALE WARNING GOING FOR THE LOWER DELAWARE BAY THROUGH
LATE THIS MORNING. OTHERWISE, THE REST OF THE WATERS HAVE A SMALL
CRAFT ADVISORY. ON THE UPPER DELAWARE BAY, WINDS SHOULD DROP
BELOW SCA THRESHOLDS BY LATE THIS MORNING. FOR THE REST OF THE
WATERS, SCA CONDITIONS ARE EXPECTED TO CONTINUE THROUGH EARLY
THIS EVENING.
OUTLOOK...
FRIDAY...SUB-SCA. FAIR. INCREASING WINDS/SEAS LATE.
FRI NIGHT/SATURDAY...SCA FLAG EXPECTED. SHOWERS.
SAT NIGHT THRU SUN NIGHT...SCA. LOW END GALE POSSIBLE SAT NIGHT. FAIR.
MONDAY/MONDAY NIGHT...SUB-SCA. FAIR.
PHI WATCHES/WARNINGS/ADVISORIES
PA...FREEZE WARNING FROM 1 AM TO 9 AM EDT FRIDAY FOR PAZ054-055-061-
062-105.
FROST ADVISORY FROM 1 AM TO 9 AM EDT FRIDAY FOR PAZ060-101-103.
NJ...FREEZE WARNING FROM 1 AM TO 9 AM EDT FRIDAY FOR NJZ001-007>010.
FROST ADVISORY FROM 1 AM TO 9 AM EDT FRIDAY FOR NJZ012-013-
015>022-027.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ450>455.
SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR ANZ430.
GALE WARNING UNTIL 10 AM EDT THIS MORNING FOR ANZ431.
SYNOPSIS...DAVIS/O'HARA
NEAR TERM...JOHNSON
SHORT TERM...JOHNSON
LONG TERM...O'HARA
AVIATION...JOHNSON/O'HARA
MARINE...JOHNSON/O'HARA
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