Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 251330
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
930 AM EDT WED MAY 25 2016

.SYNOPSIS...
High pressure will build off the Carolina coast today and persist
through Saturday. A cool front is forecast to settle across the
Northeast Thursday before moving back to the north. Another cool
front settles southward late Friday and Saturday, and as high
pressure shifts around offshore this front should get pushed
southward into our area later Sunday and Monday before lifting
back north. The next cold front may slowly approach from the
northwest later Tuesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
High pressure located off the coast of the Carolinas will
continue to influence our weather for today. We are anticipating a
mostly sunny sky with a west to southwest wind around 5 to 10 mph.

Temperatures were rising sharply this morning in response to the
sunshine and we expect highs mainly in the middle and upper 80s.
Readings are not forecast to get above the 70s in the elevated
terrain of the Poconos and northwestern New Jersey, and along the
immediate coast.

The sea breeze front is expected to meet some resistance from the
westerly synoptic flow. As a result, we do not expect the boundary
to make much progress inland this afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
The fair weather will continue tonight. Skies will be mostly
clear with some high clouds expected late. Low temperatures will
range from the upper 50s across the north and over rural
areas...to the mid 60s over the Delmarva and urban areas.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Summary...A stretch of very warm/hot conditions. An increase in
the humidity starts mainly later Thursday. A frontal boundary
nearby Thursday into Sunday combined with instability should
trigger some showers and thunderstorms mainly each afternoon and
evening across the interior, then the front pushes south some
later Sunday through Monday. There is less confidence with the
temperature forecast later Sunday and Monday given the flow
turning more onshore.

The synoptic setup is comprised of a ridge in the east that
amplifies with time though the holiday weekend. There will be
several pieces of energy deflected around this ridge with a sharp
trough possibly occurring in the vicinity of the Canadian
Maritimes starting over the holiday weekend. This setup results in
a frontal zone becoming draped from about the Great Lakes to New
England. This front looks to meander north and south through
Saturday before another front arrives. The upper air pattern may
then support this front settling into our area more Sunday and
Monday in conjunction with low pressure well to our south. Some
energy along this front combined with plenty of heating to the
south of it should result in mainly some diurnally driven
convection Friday through the holiday weekend. Overall, a washout
is not anticipated although there is still questions regarding the
details for later Sunday and Monday. We used a model blend
approach for Thursday through Friday night, then blended in the
00z WPC Guidance with continuity thereafter. Some adjustments were
then made based on additional collaboration with our neighboring
offices.

For Thursday...The 925 mb temperatures are forecast to be between
+20C and +25C. This combined with west to southwest flow will
drive the temperatures well into the 80s for much of the area. The
exception will be the coastal areas where the surface flow may
back more southerly and allow some cooler ocean influence. We
bumped up the temperatures some especially away from the coast.
Low pressure tracking into the Great Lakes should provide enough
of a downstream push to move a front back north. A few showers and
thunderstorms may develop Thursday afternoon across mainly our
western zones due to terrain circulations and local convergence,
however much of the convection should reside to our west. In
addition, the dew points will be on the rise especially at night
allowing for a more humid feel to the air. The model guidance
shows a rapid uptick in the 700 mb theta-e and PW values
especially at night.

For Friday and Saturday...The ridge axis builds nearly over our
area. This will result in very warm/hot conditions along with a
more noticeable increase in the surface dew points. Some mainly
diurnally driven convection cannot be ruled out each afternoon and
early evening. The PW values are forecast to increase to near 1.50
inches Friday and with the mid level flow more westerly this could
result in a bit more cloudiness. If this occurs, then perhaps the
temperatures are a little cooler especially Saturday. It appears
given the rather warm air mass in place, some places especially
in the urban areas of the I-95 corridor top out at 90 degrees
Friday afternoon. An area of low pressure is forecast to be slowly
approaching the Carolinas as the ridge aloft remains. Depending on
the organization of this feature some additional moisture may
eventually work northward toward our area.

For Sunday through Tuesday...As the ridge axis shifts a bit
farther north, high pressure at the surface near the Canadian
Maritimes drifts southward. This will turn our winds from the east
Sunday and Monday as a surface cool front gets pushed southward
some. The forecast challenge is how strong this push will be as it
will greatly impact the temperature forecast. As of now, we are
still expecting some cooling given an onshore flow and more
clouds. There should remain a corridor of instability especially
in the interior for some possible scattered convection Sunday
mostly in the afternoon, then possibly more showery Monday with
the onshore flow. The low to our south should be slow moving
however some of its moisture may enhance the convective potential
across our area into Tuesday.

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

A great flying weather period expected today and tonight. Skies
will remain mostly clear across the region with gentle w/sw winds.
Tonight...skc with light sw winds at the terminals.

Outlook...
Thursday and Friday...VFR overall. A few afternoon and evening
showers and thunderstorms especially Friday mostly north and west
of KPHL may result in brief times of MVFR/IFR conditions.
Southwest winds mainly up to 10 knots, however less at night. A
sea breeze may turn the winds to the southeast at KACY each
afternoon, and a bay breeze possibly affecting KILG.

Saturday and Sunday...VFR ceilings at times. Some mainly
afternoon and evening showers and thunderstorms are possible each
day, however these look scattered.

&&

.MARINE...
Sub-sca conditions expected today and tonight with a ridge of
high pressure expected across the waters. Winds will be mostly w
this morning and then back to sw this afternoon. Wind speeds will
be mostly 5 to 10 knots today and 10 to 15 knots tonight. Seas on
the ocean 2- 3 ft and 1- 2 ft across Delaware Bay.

Outlook...
Thursday through Sunday...A ridge over the area combined with
high pressure at the surface to our south and east will allow for
mainly a prolonged southerly flow across our area through Saturday
night. Winds should then shift more onshore during Sunday. The
conditions are expected to be below Small Craft Advisory criteria.
Sea breeze circulations each day may allow for a period of
increased winds near-shore during the afternoon and early
evening.

&&

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

&&

$$

Synopsis...Gorse
Near Term...Iovino
Short Term...O`Hara
Long Term...Gorse
Aviation...Gorse/O`Hara
Marine...Gorse/O`Hara


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