Area Forecast Discussion
Issued by NWS Mt. Holly, NJ-- Remove Highlighting --
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FXUS61 KPHI 280904
Area Forecast Discussion
National Weather Service Mount Holly NJ
504 AM EDT SUN AUG 28 2016
High pressure centered over the Maritimes this morning is ridged
back to the mid Atlantic states. A weak frontal boundary approaching
from the northwest is forecast to arrive during Monday afternoon and
evening and then dissipate Tuesday. A strengthening cold front from
the northwest is anticipated to pass through our region early on
Thursday followed by high pressure for Friday and Saturday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
High pressure both at the sfc and aloft will continue to influence
the weather today. It will be a sunny day and again it will feature
above norma temperatures. Highs should climb back into the upper 80s
and low 90s in most areas. Just like Saturday, it will be rather
comfortable across ern PA and nrn NJ. It will be more humid than
Saturday however over Delmarva and srn NJ where dew points will
climb near 70 degrees later today. Winds will be mostly 5 to 10 mph
from the E or SE.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
The high will have moved away by tonight. A southerly
flow with more humid air will set up across the area. We still
expect a fair weather night, but there will be some more clouds than
Sat night. Patchy fog is a gain possible. Low temperatures will
remain mild, with lows in the mid/upper 60s in most areas and low
70s over metro Philadelphia.
.LONG TERM /MONDAY THROUGH SATURDAY/...
-- Changed Discussion --500MB: The strong mid level ridge over the mid Atlantic states will
give way to a developing trough over the ne USA Thursday followed
by ridging redeveloping eastward over the weekend.
Temperatures: The top 4 warmest summer (JJA) including August
will continue through the 31st. Calendar day average temperatures
Monday- Wednesday should average 5 to 10 degrees above normal.
Thursday is the transition day with 3-5F below normal averages
anticipated for Friday and Saturday. Beyond - much of Labor Day
week...probably becoming Hot (90+) again per strong trend of the
00z/27 and 28 NAEFS and several days of GEFS 500mb showing a +2SD
height anomaly vicinity of the Great Lakes region.
Forecast basis: Unless otherwise noted, a 50 50 blend of the 00z/28
GFS/NAM MOS guidance Monday-Tuesday, thereafter the 00z/28 GFS MEX
MOS for Tuesday night and 05z/28 WPC Guidance Wednesday-Saturday.
Monday...No change as per the day shift yesterday...A mid level
short wave trough is anticipated to move across New York State and
New England during the afternoon and evening. It should push a
surface frontal boundary into our region at that time. The
guidance continues to suggest only a limited potential for
precipitation. A narrow band of precipitable water values around
1.7 inches is forecast to precede the front and there should be
marginal instability. For now it looks a bit too dry in our area
for much in the way of showers and thunderstorms. HOT it will be.
Tuesday...It appears as though the boundary will dissipate slowly
over or near Maryland, Delaware and southern New Jersey. Drying is
expected to work its way into our region from the north for Tuesday
so we are not anticipating any precipitation at that time. PWAT
decreases to 1 inch. Still very warm with 87-90F common except
cooler coastal onshore flow and the Poconos.
Wednesday...HOT. A cold front is expected to approach from the
northwest. It looks as though our best chance of showers and
thunderstorms during the coming week should be centered on
Wednesday night in advance of the front. The boundary should pass
off the coast Thursday morning.
Thursday...A cooler northwest flow develops in the wake of the
cold frontal passage, though we may not notice til late in the
day. The 00z/28 ecmwf has showers still hanging into part of the
day. so there is pop uncertainty Thursday. Increasing northwest
Friday and Saturday...Probably delightful. Seasonably cool.
northwest to north winds gusting 15-20 mph each day. The tropics
are becoming active so we may need to monitor a variety of
tropical solutions to our south for next weekend.
-- End Changed Discussion --
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
A few patches of fog expected the first part of the morning, but
other than that, VFR conditions today and tonight. Winds will remain
rather light, mostly from the East or Southeast this morning, and
South this afternoon. Few-Sct daytime cu and some ci/cs clouds are
all that can be expected today.
Monday through Wednesday morning...Mainly VFR. Late night and early
morning visibility restrictions are possible, especially Tuesday
and Wednesday mornings
Wednesday afternoon and especially Wednesday night...Mainly VFR.
However, there is a chance of MFVR conditions in any showers and
Thursday...Becoming mainly VFR. Northwest winds gust 15 kt.
A ridge of high pressure will remain across the waters today before
moving away tonight. Fair weather is expected through the period
along with sub-sca conditions. Winds will be mostly East or Southeast
both today and tonight. Winds speeds will be around 10 Knots much
of the time, perhaps a bit higher across the srn Coastal NJ waters
and DE coastal waters. Seas on the ocean will be mostly 3 to 4 ft.
Monday through Thursday...No marine headlines are anticipated. Multiple
swell groups from the east...including from distant and eventually
eastward turning Gaston.
There is a moderate risk for enhanced rip currents today. The
swells from distant tropical systems have yet to arrive. Winds are
onshore today creating some enhanced surf conditions.
The long period swells from Tropical Cyclone Gaston should become
noticeable Monday as the cyclone turns northeastward from near 55
degrees west longitude. The long period 12 to 15 second swells
are forecast to become more pronounced along the coasts of New
Jersey and Delaware on Monday and Tuesday. We continue to expect
an enhanced threat for the development of dangerous rip currents
for much of the week with onshore winds Tuesday enhancing the risk.
Presuming these swells occur as outlined above, this will eventually
impact beach behavior. Follow the advice of local lifeguards who
will be observing and your safety net. 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.
-- Changed Discussion --This section is up to date through 5 AM Today-Sunday August 28.
It may be discontinued later today.
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 is on its way for 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 3 to 4 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.
Allentown will probably 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. 78.1 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 27th.
season mean Aug Aug Aug Season
mean rer rer
abe 32 17 11 4 16-1980 41-1966
acy 27 10 10 3 11-2010 46-2010
phl 37 21 13 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.
-- End Changed Discussion --
Long Term...Drag 504a