Area Forecast Discussion
Issued by NWS Mt. Holly, NJ-- Remove Highlighting --
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FXUS61 KPHI 230045
Area Forecast Discussion
National Weather Service Mount Holly NJ
845 PM EDT MON AUG 22 2016
High pressure will pass over our region on Tuesday before moving off
the coast and drifting out to sea. A cold front approaching from the
northwest is expected to arrive on Friday. Another area of high
pressure is anticipated to build from the Great Lakes to New
England and southeastern Canada over the weekend.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
630PM ESTF: little change... lowered min temps 2-5F countryside
in ideal overnight radiational cooling and fcst gfs 2m temps.
Low temp fcst below and the last time it was this cool.
Aug 23 Forecast 63 PHL would be the coolest since the 59 June 18th
Aug 23 forecast 52 ABE would be the coolest since the 50 June 15th
Aug 23 forecast 55 ACY would be the coolest since the 55 June 27th
Aug 23 forecast 57 ILG would be the coolest since the 57 June 18th
Great weather will continue tonight and high pressure continues to
build across the area. Skies will be mostly clr overnight and winds
will become light and variable by sunset. Temperatures will be as
cool as they have been this summer with some 40s across the far
north and 50s in most other areas. The metro areas near Philadelphia
could remain in the low 60s.
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
The fine weather continue Tuesday. This high will
crest over the area during the morning and begin to slide east.
Skies will be mostly sunny and it will be another dry and
comfortable day. High temperatures will reach the low/mid 80s in
most spots. Winds will turn NE to E by afternoon...but speeds will
be less than 10 mph overall.
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Dominant features through the long term are two large high
pressure systems, leading to a continued mostly tranquil weather
Wednesday night through Thursday...Surface high shifts off shore.
The biggest impact of this will be to bring a shift to weak low
level onshore flow. Meanwhile, in the mid and upper levels, a
broad ridge builds over the southeastern U.S., which could slow
the progress of the cold front (over the Great Lakes region at
Thursday night and Friday...Cold front continues slow progress
east, though little, if any precipitation is expected primarily
because of synoptic scale subsidence thanks to the persistent
broad ridge over the southeastern U.S.. The front should arrive on
Friday. With models depicting considerable pressure rises behind
the front (thanks to a high building south out of central Canada),
expect that the front should make steady progress through the
region without stalling.
Saturday and Sunday...the region will once again be mostly
under the influence of a High pressure system, resulting in mostly
tranquil weather. However, the center of the high will stay well
north of the region. As a result, we expect temperatures will
remain above normal through this period.
Monday...An upper level short wave trough could dig southeast
towards our region through this time, bringing another small
chance for precipitation. Given the uncertainty with how far out
it is, kept the chance for precipitation no higher than 20
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Great flying weather is expected through Tuesday with high pressure
building in. The daytime cu across the area will diminish by sunset
and the winds will become light by then too. Clear skies and light
winds will be over the area tonight and early Tue. Winds will be
variable Tue, but may show a tendency to go NE or E by afternoon.
Wednesday through Thursday...VFR conditions expected.
Thursday night and Friday...mostly VFR conditions expected though
there is a slight chance (20 percent) of thunderstorms across the
Delaware Valley and Lehigh Valley (including KRDG, KABE, KTTN, KPNE,
Saturday...VFR conditions expected.
-- Changed Discussion --No marine headlines through Tuesday.
Winds will remain mostly NW this evening and then veer to N late.
On Tuesday, winds will further veer to NE during the morning.
Winds speeds later tonight and Tuesday will mostly be around 10
knots with gustiness diminishing tonight.
Wednesday through Saturday...winds and seas should stay below SCA
RIP CURRENTS: Tomorrow-Tuesday is definitely a low ENHANCED day
that may need an upgrade to moderate along our entire NJ coast in
our 530 am issuance Tuesday.
It appears that a 1 ft 12-13 second period swell will become dominant
tomorrow and during the afternoon winds will be turning onshore
enhancing the risk for the formation of dangerous rip currents.
It is very important that everyone swim in designated beach patrol
watched areas. The benign looking swell (1ft easterly 12-13
second) at both 44065 and BTHD1 has lots of energy and can result
in wave knock down and associated rip current formation.
Wednesday: ditto Tues of Low ENHANCED or possibly Moderate.
Thursday, Friday: Probably low ENHANCED, maybe slightly less
chance of moderate risk.
Developing later next weekend? some of our guidance is offering a
2 ft 15 to 17 second period southeast swell rolling into our
waters. IF that occurs and the flow is onshore...we might be
issuing our first high risk headline of the season. We just are
not sure if the GFS ensembled and ECMWF supported central Atlanticdevelopments
Water temperatures: Upwelling cool water in the 2246z satellite
imagery and water temps vcnty the entrance to De Bay and up to at
least ACY (upper 60s). Otherwise a few miles offshore much warmer
-- End Changed Discussion --
A top 6 warmest August appears assured most of our forecast area
and a top 4 warmest June-July-August for Philadelphia.
Philadelphia August normal temp 76.6. The forecast seems to be settling
in close to 80F. Odds favor the 80.2F we project now as conservative
or at least 3.6 above normal.
In any case...Philadelphia ranking includes our 330 PM forecast
temps (SFT specific values) through the 29th and the FTPRHA GFS 2m
max/min for PHL for the 30th-31st. The average of 81.9 through
the 21st will cool 1 to 2 degrees. Records date back to 1874.
1. 80.2 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. Can foresee 3 to 6 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 and #3 warmest August. Through
the 21st 77.9 but we`ll lose 1-2 degrees by the end of the month.
Records date back to 1922. Normal 71.7 projecting a positive
departure of 4.5 degrees.
1. 78.2 1980
2. 76.2 2016
3. 76.0 1937
4. 75.7 75.7
Atlantic City through the 21st has averaged 79.5 but may lose up
to 2 degrees by the end of the month. Records date back to 1874.
The August monthly normal is 74.4 and we`re projecting a positive
departure of 3.5 degrees.
1. 77.9 2016 and 2005
2. 77.1 2009
3. 77.0 1984
4. 76.9 2010
Wilmington Delaware through the 21st has averaged 80.3 but will
lose 1 to 2 degrees. Records date back to 1894. The monthly
normal is 75.2 and we`re projecting a positive departure of 3.6
degrees. The Wilmington records appear biased on the warm side
during the early stages of this period of record. Even so, Wilmington
would probably be 6th or 7th warmest in the period of record for
the month of August.
1. 86.6 1900
2. 83.8 1898
3. 82.4 1901
4. 81.5 1899
5. 80.8 1897
6. 78.8 2016 and 1895
7. 78.7 1902
Seasonal: This summer 2016 for Philadelphia will probably be the
2nd or 3rd warmest June-July-August (JJA) in the period of record
dating back to 1874.