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Area Forecast Discussion (AFD)

Issued by Philadelphia/Mt Holly (PHI)

FXUS61 KPHI 210824

Area Forecast Discussion
National Weather Service Mount Holly NJ
424 AM EDT Sat Sep 21 2019

High pressure located in North Carolina early this morning will
drift eastward and out to sea today and Sunday. A cold front is
expected to approach from the northwest on Monday and it should
pass through our region on Monday night. Another area of high 
pressure is anticipated to follow for Tuesday and Wednesday. The
next cold front from the northwest is forecast to arrive late 
on Thursday with high pressure expected for Friday.


The sky was clear overnight and the wind was light. Valley fog 
developed in parts of eastern Pennsylvania and northern New 
Jersey. The fog will lift and dissipate by mid morning.

A mid level ridge will remain over the eastern states today. 
Surface high pressure located in North Carolina early this 
morning will drift off the coast. The high will continue to 
bring dry weather conditions to our region. We are anticipating 
a mostly sunny sky with a few cumulus and some patchy cirrus 

A light southwest to south wind will develop in our region on 
the back side of the high. Maximum temperatures will favor the 
lower and middle 80s. The readings will be about 8 to 10 degrees
above normal for September 21.


A short wave trough is expected to ride over the mid level 
ridge tonight. The axis of the trough is forecast to approach 
our region from the west late tonight. The feature will not have
much moisture associated with it. As a result, we are 
anticipating only some scattered cloud cover. Meanwhile, the 
surface high will continue to move slowly out to sea.

The wind is forecast to become light and variable for tonight. 
Low temperatures are expected to be mainly in the upper 50s and 
the lower 60s.


Not much change in the extended period as we are largely 
dominated by high pressure. Main opportunity for precipitation 
will be with the frontal passage on Monday night. 

A cold front will approach the region from the west on Monday, 
crossing through the area Monday night. Low level moisture will 
be on the rise in the return flow around the departing high 
pressure. Flow looks to be pretty progressive with the front 
working through the area Monday night and then offshore by 
Tuesday morning. Some instability may develop head of the front 
with the best forcing right in front of and along the boundary.

Once the front moves through, high pressure starts to build 
back into the region. There may be a weak front that moves 
through on Thursday but most guidance shows little moisture 
around and it may not be much more than a wind shift across our 


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

Today...Local MVFR conditions early this morning around KRDG, 
otherwise VFR under a mostly clear sky. West to south wind 4 to 
8 knots.

Tonight...VFR with scattered clouds developing. Variable wind 6
knots or less.

Sunday and Sunday night...Mainly VFR. Southwest wind 5 to 10 

Monday...Mainly VFR. A chance of afternoon showers. Southwest 
wind around 10 knots.

Monday night...Mainly VFR. A chance of showers. Southwest wind 
5 to 10 knots becoming northwest.

Tuesday...Mainly VFR. Northwest wind around 10 knots.

Tuesday night...Mainly VFR. Northwest wind 5 to 10 knots.

Wednesday...Mainly VFR. Northwest wind 5 to 10 knots becoming 


High pressure will continue to influence the coastal waters of 
New Jersey and Delaware into tonight. The wind should settle 
into the southwest and south around 10 to 15 knots.

Waves of 4 to 6 feet this morning should subside gradually to 3
to 4 feet during the course of the day. A Small Craft Advisory 
remains in effect until noon for our coastal waters north of 
Atlantic City, and until 4:00 PM for our coastal waters from the
Atlantic City area down to Fenwick Island, Delaware.

Sunday...No marine headlines are anticipated.

Sunday night into Monday night...Southwest to south wind 
gusting around 25 knots at times. Waves on our ocean waters may 
build around 5 feet.

Tuesday through Wednesday...No marine headlines are 

A long period easterly swell with a wave period of 12 to 14 
seconds is expected to continue for today. Breaking waves are 
forecast to be in the 3 to 4 foot range. As a result, there is a
high risk for the development of dangerous rip currents for 
today along the coasts of Delaware and New Jersey.

The long period easterly swell is anticipated to persist into 
Sunday. Wave heights will likely subside a bit, so we are 
expecting a moderate risk of rip currents at that time.


NJ...High Rip Current Risk through this evening for NJZ014-024>026.
DE...High Rip Current Risk through this evening for DEZ004.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for 
     Small Craft Advisory until noon EDT today for ANZ450-451.



Near Term...Iovino
Short Term...Iovino
Long Term...Meola