Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
FXUS61 KPHI 291313
Area Forecast Discussion
National Weather Service Mount Holly NJ
913 AM EDT MON AUG 29 2016
A weak frontal boundary crossing New York and northwest Pennsylvania
will slide down into our area today, then slowly dissipate Tuesday.
A tropical Depression is anticipated to pass well to the southeast
of our area on Wednesday. A strong cold front will move through the
mid Atlantic states Thursday morning. Great Lakes high pressure
should dominate Friday, Saturday and Sunday, while tropical low
pressure is monitored moving northeastward off the southeast coast
of the United States.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A weak front will cross the area today with an increase in mid and
level clouds at times. However, moisture and lift with this front
are both very limited and not expected to produce precipitation
across the region for the remainder of the day/ It will be another
above normal temperatures day with upper 80s and low 90s for high
temps today. Winds will be mostly 5 to 15 mph from the W or NW.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
Fair weather expected tonight as the weak front moves away. Drier
and a bit cooler air will move across the area from the N/NW. Low
temperatures tonight will be cooler than the past several days,
especially across the nrn areas. Sky cover will be partly cloudy to
.LONG TERM /TUESDAY THROUGH SUNDAY/...
**Dry spell may continue through at least Labor Day**
500 MB: An intensifying short wave moving from south central Canada
Tuesday through the Great Lakes Wednesday, into the northeast
Thursday, then to the Maritimes Friday, is followed by ridging over
the weekend into early next week. A piece of the trough will be
left behind along the mid Atlantic coast this coming weekend, which
will need to be monitored for possible tropical interaction near
the east coast.
Temperatures: The top 4 warmest summer (JJA) including August will
continue through the 31st. Calendar day averages Tuesday and Wednesday
will be 3 to 7 degrees above normal, starting to cool Thursday,
then near or slightly below normal Friday-Sunday. Beyond - beginning
around or shortly after Labor Day, it should become hot again (90+)
again per continuous and strong trend of the 00z/27-29 NAEFS and
several days of GEFS 500mb showing a +2SD height anomaly vicinity
of the Great Lakes region and southeast Canada.
Forecast basis: Unless otherwise noted, a 50 50 blend of the 00z/29
GFS/NAM MOS guidance Tuesday-Wednesday, thereafter the 00z/29 GFS
MEXMOS Wednesday night and 05z/29 WPC guidance Thursday-Sunday.
Tuesday...Fair and several degrees cooler with a dissipating frontal
boundary overhead. Pwat lowers to 1" PHL. A sunny start then sct-
bkn clouds develop during the afternoon near 5000 ft. Probable 4
day heat wave in jeopardy at PHL and ABE, but probably continues a
5th day at KESN (MD e shore). Have fcst 89F at PHL/ABE Tuesday,
the occurrence for which my confidence is greater, than 90, but
its possible that it still can reach 90 at both locations.
Wednesday...patchy fog and haze possible near sunrise, otherwise
becoming hot and more humid as pwat increases to 1.5" I-95 sewd.
That may not be enough pwat to permit afternoon thunderstorms.
Tropics: It appears as though Tropical Depression Eight will remain
far enough to our southeast on Wednesday as not to impact our land
Wednesday night...Partly cloudy. Showers and thunderstorms possible,
per the Great Lakes short wave and cold frontal passage.
Thursday...any leftover showers in the morning should end by Noon.
partial clearing. north wind develops.
Friday - Sunday...Probably delightful. Seasonable temperatures
-actually a little chilly north of I-78 where some mid 40s
possible in the typical cold low lying countryside areas. light
mostly east wind, possibly gusty 15-20 mph along the coastal plain
during the afternoons. We will have to monitor any tropical
developments off the se USA coast since a piece of the Thursdays
trough will be left behind near the mid Atlantic coast next
.AVIATION /13Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
VFR, overall a good flying weather day is expected. A weak front
will cross the area this morning and it will cause winds to shift
from the present S/SW direction to W/NW by afternoon. The winds
will further veer to N or N/NE tonight. Winds speeds will be
mostly 5 to 10 knots today and tonight. Some clouds will accompany
the front, but no low cigs are expected.
Tuesday through Wednesday morning...Mainly VFR. Early morning
visibility restrictions are possible. Light wind.
Later Wednesday afternoon into Wednesday night...Mainly VFR.
However, there is a chance of sub VFR conditions in any showers
and thunderstorms that develop. Southwest wind in the afternoon
becoming west at night.
Thursday...any leftover sub VFR conditions in morning showers or a
thunderstorm should give way to a VFR afternoon. winds becoming
Friday...VFR. northeast wind.
A weak front will cross the waters late this afternoon and
tonight. Winds will begin the day mostly from a wrly direction and
then turn southwest later this afternoon. Once the front passes,
winds will become northerly behind it. Wind speeds/gusts will remain
below SCA conditions. Fair weather is expected today and tonight,
but a brief shower could develop later today over the waters, confid
in this is low. Seas will be around 3-4 ft today and tonight on the
ocean with a longer period swell developing.
Tuesday through Friday...No marine headlines are anticipated
though it may be close for swells. The long period swells probably
will create rough conditions in and around the inlets along the
coasts of New Jersey and Delaware.
Today: A Moderate risk for the formation of dangerous rip currents.
This in part due to increased rescues yesterday (3 ft 8 seconds).
The swells from distant tropical systems have arrived (14-15 second
period has become dominant), and this should be the theme for much
of the week. The heights of the swells are still only 2-3 ft, but
the power of the swells will be enough to justify the moderate
Tuesday: The long period 12 to 15 second swells are forecast to
build from 3 feet to near 4 feet along the coasts of New Jersey
and Delaware. This would put us in a strong moderate risk. A high
risk headline issuance is still possible for Tuesday.
Wednesday: GFS and tropical modeled swell/period wave groups
strongly suggest a moderate risk for the formation of dangerous
rip currents continues.
In terms of safety, follow the advice of local lifeguards who will
be observing. There may be some beach closures, all dependent on
the reality that develops. This is not a time to swim on your own
without lifeguard presence. Additionally, waders are cautioned not
to turn their backs to the waves when coming out of the water.
Wave knock down can result in upper torso injury
(dislocations/spinal cord injuries).
A beach hazards statement was issued at 605 AM to alert for the
rough surf for this week into the coming weekend, this in part
based on NHCs outlook compared with the GFS/EC operational cycles.
This section is up to date through 435 AM Today-Monday August 29.
A top 4 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 will establish its warmest August on record (dating
back to 1874). More than 4 degrees above normal.
This Philadelphia August ranking includes our forecast temps (SFT
specific values) through the 31st. The 30 year normal is 76.6
Records date back to 1874.
1. ~81.0 2016
2. 79.9 1980
3. 79.8 2001 and 1995
Regarding whether August can tie its record of 17 90F days. Its
possible but not probable. Foresee an additional 2 to 3 more 90
degree days to add onto the 13 we have so far this month. The
record of 17 was set in 1995. The mean for the month is only 5.
Tuesday is the possible day for breaking a modest heat wave and
eliminating a chance at a record equaling 17, 90 degree days in
Allentown will rank #2 warmest August. Records date back to 1922.
Normal is 71.7 and we are projecting a positive departure of
around 5 degrees.
1. 78.2 1980
2. 76.6 2016
3. 76.0 1937
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. The forecast and climate for
Atlantic City has greater variability than Allentown and
Philadelphia due to proximity to water on sea breeze days and
notable radiational cooling on some nights.
1. 78.2 2016
2. 77.9 2005
3. 77.1 2009
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 75.0 or a ranking of around
#2 in the por.
1 75.3 1949
2 75.0 2016
3 74.6 2005 and 1980
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 through the 28th.
season mean Aug Aug Aug Season
mean rer rer
abe 33 17 12 4 16-1980 41-1966
acy 27 10 10 3 11-2010 46-2010
phl 38 21 14 5 17-1995 55-2010
ilg 32 20 13 5 23-1895 59-1895
Rainfall: Considerable uncertainty exists regarding additional
rainfall in August, so this part of the climate is stated with
Presuming no further measurable rain this month of August...the
current ACY value of 1.10 would rank the 6th driest August on
record, after a 6th wettest July.
For Philadelphia, the June-August seasonal total of 7.45 inches
is so far, the 12th driest summer...again this presumes no further
measurable rain in August.
NJ...Beach Hazards Statement through Tuesday evening for NJZ014-
DE...Beach Hazards Statement through Tuesday evening for DEZ004.