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Area Forecast Discussion (AFD)

Issued by Philadelphia/Mt Holly (PHI)

FXUS61 KPHI 220501

Area Forecast Discussion
National Weather Service Mount Holly NJ
101 AM EDT Sun Sep 22 2019

High pressure will continue to move slowly off the Carolina coast 
through Sunday. A weak surface low in the Midwest on Sunday 
night will lift northeastward into New England and far southeast
Canada by Tuesday. An attendant cold front will move through 
the Mid- Atlantic region Monday night. High pressure build into 
the Northeast for midweek, with another cold front moving 
through the area Thursday night. Another broad surface high will
follow to close the week. 


100 AM...High pressure continues to dominate our weather and 
this will result in continuing mainly clear skies overnight with
light winds. Temperatures have been dropping off pretty good as
a result of these conditions...especially in valleys and low 
lying areas and as this continues expect some patchy fog 
development to continue overnight for these areas. 

Heading into the day Sunday, the ridge aloft breaks down while 
high pressure at the surface moves offshore. This will allow for
a return flow with very warm temperatures and increasing 
moisture through the day. Late day, there is a chance some 
showers may develop to our west. They are mostly expected to 
stay out of our area and remain near the surface trough though there
will be just a slight chance of a few showers or storms across 
the Poconos late in the afternoon. Highs will be mainly in the
middle to upper 80s except a bit cooler along the coast, the
Delaware Bay, and the southern Poconos. 

High pressure continues to move eastward over the Atlantic
Sunday night while a developing low pressure system and
associated cold front moves east through the Great Lakes. This 
will keep the area in a mild S/SW flow resulting in warmer 
overnight lows compared to this morning. Skies should remain 
mainly clear to partly cloudy. Lows will be mostly in the middle
to upper 60s...warmest over the Delmarva NE along the urban 
corridor through Philly. It will be a a bit cooler in the 
southern Poconos where lows should get down into the low 60s. 

Monday through Tuesday...

Warmth continues Monday as the upper-level ridge to our southwest 
feeds warm return flow into the mid-Atlantic and Northeast. 
Meanwhile to our west, another shortwave trough will make its way 
across the Great Lakes as a surface low and cold front track across 
the Keystone state. Showers and thunderstorms should hold off for 
most of the day as the main low-level convergent forcing remains 
along the front. A few showers and storms may begin to move into our 
western counties by late morning. However, the best chances should 
hold off until late afternoon into the evening. Severe weather is 
not expected at this point given the lack of instability, though a 
few stronger thunderstorms may still be possible. Highs look to top 
in the mid to upper 80s with the axis of warmest temperatures along 
the I-95 corridor from New York to DC. 

Dry weather returns Tuesday as the front pushes south of the CWA and 
winds turn northwesterly. Cooler temperatures will result in 
forecast highs about ten degrees cooler in the mid to upper 70s.

Tuesday night through Saturday...

Low pressure over northern New England continues to depart Tuesday 
night. Meanwhile, surface high pressure builds in from the west with 
the center of the high building into West Virginia. High pressure 
will then dominate much of the midweek period, with the high sliding 
off the Southeast U.S. coast during the day Wednesday, and then 
moving out to sea Wednesday night.

Low pressure tracking across Canada will drag a weak cold front 
towards the region Wednesday night, but it will not fully cross 
until late Thursday. The bulk of the upper shortwave energy looks to 
stay well north of the region, so will only carry slight chance PoPs 
for the southern Poconos, Lehigh Valley, and northern New Jersey.

High pressure returns thereafter, building nearly overhead on Friday 
before moving offshore on Saturday. Another frontal system may 
approach for Saturday night.

Highs during the middle to the end of the week will mostly be a few 
degrees above normal, generally topping off in the mid to upper 70s. 
The warmest day looks to be Thursday, when the area is in the warm 
sector ahead of the approaching cold front, when highs will be in 
the low to mid 80s.

The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY and surrounding areas.

Overnight...Mostly VFR conditions expected. Patchy fog may 
develop for a few locations, mainly at MIV but also also
potentially at RDG and ACY. Winds light and variable. 

Sunday...VFR conditions expected. Light and variable winds 
early, increasing out of the southwest 5-10 knots during the 
day, with gusts up to 15 knots possible. 

Sunday night...Mainly VFR with light SW winds. 


Monday and Monday night...Mainly VFR expected. MVFR or lower 
possible in scattered afternoon showers. Southwest winds around 
5 to 10 knots with some gusts around 15 to 20 knots (more likely
closer to KACY). Winds will turn to the west and then northwest
late behind a cold frontal passage. 

Tuesday through Tuesday night...Mainly VFR expected. Northwest winds 
around 5 to 10 knots. 

Wednesday through Wednesday night...Mainly VFR expected. Northwest 
winds around 5 to 10 knots turning southwest late.  

Thursday...Mainly VFR expected. Southwest winds around 5 to 10 knots.


Overnight...Sub-Small Craft Advisory conditions on tap through 
the overnight. 

Sunday...Conditions expected to remain below advisory levels, 
although winds may gust around 20 knots at times in the 


Sunday night through Monday night...Sustained south to 
southwest winds around 15-20 knots will gust up to 25 knots at 
times, especially over the ocean waters. Winds will begin to die
down late Monday night. Seas will build to around 5 feet by 
Monday afternoon and evening before subsiding slightly 

Tuesday through Thursday...Conditions are expected to remain 
below Small Craft Advisory criteria.


There is a MODERATE risk for the development of dangerous rip 
currents at New Jersey and Delaware beaches through Sunday.




Near Term...Fitzsimmons
Short Term...Fitzsimmons
Long Term...Davis/MPS