Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 270156
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
956 PM EDT THU MAY 26 2016

.SYNOPSIS...
High pressure anchored over the Mid-Atlantic States will
move offshore this weekend as a low pressure system moves northwest
toward the southeast coastline. By Monday, a cold front will move
southeast into the Great Lakes then into our region by the middle of
the week. A low pressure system will continue to linger off
the southeast coastline through most of next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
High pressure located off the coast will continue to influence our
weather even as a mid level short wave trough approaches from the
west this evening. The feature is expected to flatten during the
night as it reaches our forecast area. A deck of mid-level cloud
cover should keep temperatures from dropping below the 60s in most
spots as well as limit the extent of the fog development overnight.

Scattered convection was developing over West Virginia, western
Virginia, and western and central Pennsylvania at mid afternoon in
advance of the mid level short wave. The precipitation was drifting
eastward. It is not expected to begin moving into our northwestern
counties until after dark. The loss of daytime heating should cause
the convection to weaken to scattered light rain showers which
should dissipate in our region during the night. We have confined
the chance of precipitation mainly to our counties in eastern
Pennsylvania and northern New Jersey.

&&

.SHORT TERM / FRIDAY THROUGH 6 AM FRIDAY/...
High pressure off the coast will continue to draw very warm and
increasingly humid air into our region on Friday. Early morning mid
level clouds should dissipate with cumulus expected to develop for
the afternoon.

A pool of instability is anticipated to form over central
Pennsylvania with scattered showers and thunderstorms expected to
develop in that area. The convection should drift eastward into our
forecast area during the afternoon. We will mention a chance of
showers and thunderstorms mainly for our counties in eastern
Pennsylvania and northern New Jersey. PoPs were lowered a bit with
the 930 PM ESTF update as it appears that models, in particular the
NAM/GFS, are overdoing the low-level moisture/instability and thus
convective potential. There also doesn`t appear to be much
organized lift present across the area until perhaps a shortwave
trough approaches from the west toward sunset.

Friday will be another very warm day with temperatures approaching 90
degrees in much of our region.

&&

.LONG TERM /FRIDAY THROUGH THURSDAY/...
Saturday through Sunday Night: High pressure will be firmly in place
over the region. Subsistence from the high pressure will prevent
normal pop-up afternoon thunderstorm formation both days except in
the higher terrain areas in the Southern Poconos and NW NJ. A
gradual tick upward with humidity is expected, making it feel even
more like summer. High temperatures will likely be a couple degrees
warmer than met/mav with overnight lows climbing due to the
increased humidity.

Memorial Day: A low pressure system is likely to be located just off
the Southeast United States coastline. With a broad mid-level ridge
just offshore moisture is likely to be transported northward along
the eastern seaboard. Some uncertainty is present with this low
potentially become tropical. The National Hurricane Center currently
has a 70% chance of this forming into a sub-tropical or tropical
system between today and early next week.

While any tropical impacts would be well south of the region, the
moisture interaction with lift along an approaching cold frontal
boundary. This will lead to a good chance of showers and
thunderstorms with a heavy rainfall threat. PW values are also
modeled to approach 2 inches along with a modeled long-skinny CAPE
profile both also suggesting the prospects for heavy downpours with
thunderstorms. Temperatures will likely be kept down as well due to
cloud cover and thunderstorms.

Monday night through Tuesday night: The cold frontal boundary will
likely continue to be close to the region and serve as a focal point
for additional scattered showers and thunderstorms, potentially
moving through by Tuesday. With the more scattered coverage of the
showers and storms, daytime temperatures will rebound a bit on
Tuesday after a muggy start.

Wednesday and Thursday: Another low pressure system and cold front
will move into the Central Plains with our region in the warm sector
with high pressure to the northeast. However, mid level temperatures
look cooler than with the warm-up this weekend. Forecast close to
WPC guidance.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Mainly VFR conditions are anticipated through 0800z before patchy
fog may develop toward daybreak in the favored rural/fog-prone
terminals.

A deck of mid level clouds is forecast to be overhead from the
overnight hours into early Friday morning. There is the potential
for some MVFR visibility restriction around daybreak.

Mainly VFR conditions are expected for Friday. However, scattered
showers and thunderstorms may impact the area around KRDG and KABE
in the afternoon.

A southwest to south wind around 5 to 10 knots into this evening
should become light and variable for tonight. The wind should settle
into the south on Friday at speeds near 10 knots.

OUTLOOK...

Friday Night through Sunday: Mainly VFR, southerly winds 5-10 knots
with gusts around 15 knots Saturday and Sunday afternoons. Isolated
thunderstorms possibile for KABE.

Sunday night through Monday night: MVFR/IFR ceilings possibile.
Periods of showers and thunderstorms, the highest chance of
thunderstorms is on Monday. Southerly winds up to 15 knots.

Tuesday: Mainly VFR, winds under 15 knots. An isolated
thunderstorm is possibile.

&&

.MARINE...
High pressure located off the coast will maintain a southerly flow
on the coastal waters of New Jersey and Delaware for tonight and
Friday. Wind speeds will favor the 10 to 15 knot range. Wave heights
on our ocean waters should be around 2 to 3 feet. Waves on Delaware
Bay will be 2 feet or less.

OUTLOOK... Seas will remain from from three to four feet. Some
southerly wind gusts around 15 mph are possible from Sunday
through Tuesday in the afternoons.

RIP CURRENTS: We are forecasting a low risk for the formation of
dangerous rip currents, with potential near moderate risk along
northern ocean county and monmouth county this afternoon where the
southeast southeast wind may be a little stronger. Since it will
be another very warm day, and many if not all beaches are
unguarded, swimming is not advised. yesterday there was a fatality
nearby just to our north. Fatalities can easily happen at
unguarded locations. water temperatures are not especially
warm...close to 60F which is near or slightly below normal. If
going to the beach today...be safe.

&&

.CLIMATE...
The Philadelphia monthly average temperature continues to project
only about 1f below normal... with this current end of the month
stretch of above normal temperatures denting the first 24 days,
nearly 4 degree below average.

Precipitation amounts with respect to May look somewhat uncertain
based on how much tropical moisture enters the region on Monday.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$
Synopsis...Gaines/Robertson
Near Term...Klein
Short Term...Iovino/Klein
Long Term...Gaines
Aviation...Gaines/Iovino/Klein
Marine...Gaines/Iovino/Klein
Climate...Drag



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