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Area Forecast Discussion (AFD)

Issued by Philadelphia/Mt Holly (PHI)

FXUS61 KPHI 211521

Area Forecast Discussion
National Weather Service Mount Holly NJ
1121 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.


All of the fog has lifted and burned off this morning, leaving
behind mostly clear skies with only some high cirrus clouds
overhead. The mostly clear skies will continue across the area
today, and some afternoon cumulus may also develop. No
precipitation is expected slight ridging aloft and dry air
through the column will keep precipitation from occurring.

High pressure located offshore of the Carolina coasts will shift
winds to a southwest to south direction. 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.


The mid level ridge over the eastern states will continue to 
flatten on Sunday and Monday, as a trough moves from the Dakotas
to the Great Lakes. The axis of the trough is forecast to pass 
over the northeastern states from Monday night into Tuesday. The
surface cold front associated with the mid level feature is 
expected to move through our region on Monday night.

Surface high pressure will begin to lose its influence over our
weather on Sunday and Sunday night but not before bringing 
another mostly sunny and warm day. The southwest to south 
surface flow will result in a noticeable increase in humidity.

Monday will be very warm and humid with an increase in cloud 
cover. As the cold front approaches from the west, there will be
a chance of showers in the afternoon, mainly in eastern 
Pennsylvania and northern New Jersey. The chance of showers will
likely spread eastward into central and southern New Jersey, 
northeastern Maryland and Delaware on Monday evening. Marginal 
instability is anticipated, so we will keep the slight chance of

The cold front is forecast to push to our east and southeast 
during the mid week period. High pressure is expected to build 
from the Ohio River Valley on Tuesday to the waters off the 
southeast coast on Wednesday, bringing a couple of additional 
dry days to our region. 

Another mid level trough is forecast to pass across the Great 
Lakes and the northeastern states from Wednesday night into 
Thursday. It should pull a moisture starved cold front through 
eastern Pennsylvania, northeastern Maryland, Delaware and New 
Jersey late on Thursday. Surface high pressure is expected to 
follow for Friday. 

Above normal temperatures are anticipated for Sunday and 
Monday. Readings should return near normal with lowering 
humidity for Tuesday before both creep upward again from 
Wednesday through Friday.


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

Today...VFR under a mostly clear sky. West to south wind 4 to 8

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/Robertson
Short Term...Iovino
Long Term...Iovino