Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 250146

Area Forecast Discussion
National Weather Service Mount Holly NJ
946 PM EDT WED AUG 24 2016

High pressure offshore will continue to move east through Friday.
Low pressure will move across Canada and send a weak cold front
across the mid Atlantic states late Friday. Another high pressure
system will build in for the weekend. Low pressure will move through
Canada early next week and another front may affect our weather
next Monday and Tuesday.


930 PM ESTF: minor adjustments to temp trends through the night
and no big changes.

Surface high pressure continues to push offshore tonight.
Meanwhile, a weak cold front over the Midwest will move into the
Great Lakes. Mainly warm and quiet for the local area tonight, but
there may be some convective cloud debris from the storms upstream
passing overhead very late at night.

Dewpoints are up from 24 hours ago.

With S to SW flow persisting through the overnight hours, low level
humidity levels will continue to creep up. UPS cross over tool
gave spotty fog to parts of countryside NJ and ne PA. Temperatures
should be around 2 degrees above normal.


Low pressure over Canada will continue to drag a cold front through
the OH Valley and towards the local region on Thursday. Surface high
pressure off the Mid-Atlantic coast continues to push offshore, but
upper level ridging will hold firm over the area with the approach
of that front. The front almost appears to wash out as it moves
into the region late in the afternoon. Best forcing remains to the N
and W. The upper ridging should keep precip from developing across
most of the area, but will carry slight chance POPs, and cannot rule
out a rumble of thunder or 2 into eastern PA.

Southerly flow continues to usher a warmer and more humid airmass
into the region on Thursday. Southwest wind may gust 20 mph during
the afternoon. Temps may nudge 90 in PHL and in general max temps
should be around 6 degrees above normal.


Mostly good weather for the longer range part of the forecast. A
cold front will cross the area Thursday night and Friday, but the
front is weakening and the showers and few tstms that accompany it
will not be anything out of the ordinary for the summer. High
pressure will bring nice weather for the weekend. Another low
pressure system and cold front will move through for early next
week. Again, more sct showers and tstms will affect our weather

Calendar day average temperatures for the long range will be
above normal with averages Friday about 10 degrees above normal,
then 5 to 9 degrees above normal daily thereafter through Wednesday.
Highs will be in the upper 80s to low 90s across the urban areas
and Delmarva. Highs across the Nrn NJ and srn Poconos areas will
be in the 80s. The warmest and most uncomfortable conditions will
be on Friday. The dew points and temperatures on Friday may bring
heat index values into the upper 90s or even 100 across the urban


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

Remainder of tonight...VFR. Light southerly winds. Local MVFR
visibility is possible toward daybreak Thursday due to light fog,
mainly at RDG, ABE and MIV but not yet in the TAF.

Thursday...VFR. Isolated SHRA possible which could temporarily lower
conditions. South to southwest winds increase to 5-10 KT with
gusts near 20 kt in the afternoon.


Thu Night thru Monday...Mostly VFR conditions expected. Sct tstms
Thu night and Fri may bring short period of lower cigs/vsbys.


No marine headlines through Thursday. A 1 foot 12-13 second ese swell
is becoming more evident. It may increase to 2 feet Thursday?
Still...not a marine hazard.

High pressure off the Mid-Atlantic coast continues to move offshore
tonight through Thursday. A cold front approaches from the west on
Thursday. S winds will range from 5-10 KT tonight with gusts
15-20 kt probably diminishing late, then will increase to 10-15 KT
during the day Thursday. Cannot rule out a few gusts to 25 KT late
Thursday for northern NJ ocean zones, but will hold off on issuing
a SCA at this time.


Thursday night through Monday...Sub-sca conditions are expected.
Close to SCA gusts may occur on the northern NJ waters Thu night
and early fri. Sct tstms Thu night/Fri and again early next week.

For Thursday...The risk for the formation of dangerous rip
currents is low enhanced except moderate for Ocean and Monmouth
counties, especially late afternoon when the southerly wind
increases to 15 kt and the tide is moving into the lower half of
the tide cycle. Confidence on moderate risk occurrence and extent
is below average. If a 2 ft 10-12 second swell does not materialize
the risk will lessen.

No matter: Swim in the presence of lifeguards. About 55% of
the rip current fatalities in our waters since 1998 have been
after the beach patrols go home, or between roughly 530 and 730
PM. August is our more fatal month...95% were men and 50 percent
between 18 and 35 years of age. 60 percent occur with maximum temps
above 85 at philadelphia, over 60 percent died with water temps
above 70.

Friday and Saturday are outlooking low enhanced risk.

Then this coming Sunday-Wednesday...model ensemble guidance on
every successive cycle continues to send 2-4 ft long period (15 to
17 second) east southeast swell into our waters from the central
Atlantic - Gaston. It could be even higher but we`re taking the
conservative approach at this time from this distant offshore
hurricane. This is all dependent on size, strength and track but
there is little doubt that swells will build here...just how much
is the question. Swimming and wading dangers will probably increase.
For now we`re anticipating a moderate or greater risk for Monday-
Wednesday and possibly starting Sunday.


There is some potential for a heat wave beginning Thursday or
more likely Friday.

A top 5 warmest August appears assured most of our forecast area
with record monthly warmth likely at PHL.

A top 3 warmest June-July-August for Philadelphia, Allentown and
possibly Atlantic City.

Philadelphia is on its way for its warmest August on record
(dating back to 1874). More than 4 degrees above normal. Odds
still favor the monthly average rising beyond the currently
projected 80.8 as the 12z/24 ECMWF is 1-2 degrees warmer than the
12z/24 GFS Saturday- Tuesday. Model mid level heights (500mb) are
1 to 2 SD above normal through most of this period. The ridge
weakens toward Sept 2-3 then impressively warms again by Sept 7.

Philadelphia August ranking includes our 330 PM forecast temps (SFT
specific values) through the 31st. The 30 year normal is 76.6
Records date back to 1874.

1. 80.8 2016
2. 79.9 1980
3. 79.8 2001 and 1995
4. 79.6 2005
5. 79.5 2002

Regarding whether August can tie its record of 17 90F days. Its
possible but not probable. Foresee 3 to 5 more 90 degree days to add
onto the 11 we have so far this month. The record of 17 was set in
1995. The mean for the month is only 5.

Allentown will probably rank #2 warmest August. Records date back to
1922. Normal is 71.7 and we are projecting a positive departure of
at least 5 degrees.

1. 78.2 1980

2. 76.8 2016

3. 76.0 1937

4. 75.7 1955

Atlantic City records date back to 1874. The August monthly normal
is 74.4 and we`re projecting a positive departure of nearly 4
degrees. As it stands, Atlantic City will rank #1 or #2 warmest
August with very little chance of slipping to #3.

1. 78.2 2016

2. 77.9 2005

3. 77.1 2009

4. 77.0 1984

Seasonal: This summer 2016 for Philadelphia will probably be the 2nd
warmest June-July-August (JJA) in the period of record dating back
to 1874.

1. 79.6 2010
2. 78.8 2016
3. 78.6 1995
4. 78.3 1994

Allentown seasonal avg is projecting 74.9 or a ranking of around
#2 in the por.

1 75.3 1949

2 74.9 2016

3 74.6 2005 and 1980

4 74.3 1943 and 1937

Atlantic City seasonal average is projecting 75.8...4th warmest in
the por.

1. 77.5 2010

2. 77.0 2011

3. 75.9 2005

4. 75.8 2016

5. 75.5 2008

90 degree days

season       mean  Aug  Aug       Aug      Season
                        mean      rer      rer

abe  30      17     9   4         16-1980  41-1966

acy  26      10     9   3         11-2010  46-2010

phl  35      21    11   5         17-1995  55-2010

ilg  30      20     11  5         23-1895  59-1895

All the data including the forecast will be rechecked for the 330
am Saturday AFD. In the meantime, this part of the climate section
will probably be discarded around 330 am Thursday.




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