Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 210747
AFDPHI

Area Forecast Discussion...CORRECTED
National Weather Service Mount Holly NJ
347 AM EDT Tue Mar 21 2017

.SYNOPSIS...
Weak low pressure passes through the Mid-Atlantic this morning.
A cold front approaches tonight and passes through the region
by Wednesday morning. High pressure then builds in from the west
and moves offshore by the end of the week. As it does, a warm
front lifts north through the region on Friday. Low pressure
then approaches late in the upcoming weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A weak surface low will pass to our south this morning, while a
weak surface trough will move into the area from the west later
this morning as well. Meanwhile, a mid-level short
wave/voticity impulse is approaching the area this morning and
has sparked off an area of showers to our west. These showers
will move across the area through the morning hours, and will
generally be light in nature. As the short wave passes east of
the area later this morning, any showers will dissipate as they
move offshore. Cloud cover across the area this morning will
begin to break up and thin out as the short wave moves eastward
as well. The rest of the day will shape up quite nicely with
most places a few degrees above normal.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
A cold front will move across the area overnight tonight,
however no precipitation is expected as it is fairly moisture
starved. If there would be any precipitation it would across the
far south where the best chance for enhance low-mid level
moisture is forecast. Behind the front, cool air and gusty winds
will develop by daybreak. Winds behind the front could start
gusting 20-25 mph during the pre-dawn hours Wednesday.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Cold front will be south of the Mid-Atlantic region by
Wednesday morning, and then strong CAA will be underway with
well below normal temperatures for the mid-week period. Low
pressure near the Canadian Maritimes will intensify, and
although there should not be many direct impacts from this low,
a tight NW pressure gradient will form between that and high
pressure building into the Great Lakes. This will tap into cold
Canadian air, resulting in highs in the 20s in the Poconos, 30s
for most of PA/NJ, and in the low 40s for MD/DE. With NW winds
15-20 MPH with gusts up to 30 MPH, wind chills will range from
the single digits up north to the 20s for most of the CWA.

Lows Wednesday night will be quite cold for this time of the
year, ranging from the single digits in the Poconos to the teens
for much of NJ/PA, and around 20 for the Delmarva.

Temperatures moderate a bit on Thursday as heights rise as the
low over the Canadian Maritimes moves offshore, and high
pressure over the Great Lakes builds east. Although still below
normal, highs will be in the 30s and 40s.

By Friday, high pressure moves off the Mid-Atlantic coast, and
return flow sets up as a warm front lifts towards the region.
Some overrunning precip will develop ahead of that warm front,
and a brief period of freezing rain is possible for the Lehigh
Valley/Pocono Mountains early Friday morning. Rain then develops
for most of the area by Friday afternoon as that warm front
continues to lift north through the region. Temperatures return
back closer to normal, topping off in the 40s and 50s.

On Saturday, high pressure off the Mid-Atlantic coast drifts
out to sea. Meanwhile, low pressure organizes over the Southern
Plains and Midwest. This will put the Northeast and Mid-Atlantic
in the warm sector, and temperatures will soar well into the
60s, and possibly the low 70s across MD/DE. Although some sites
may come close, high temperature records look to be safe.

Thereafter, low pressure over the Midwest tracks east through
the Ohio Valley and then towards the Appalachians Sunday and
Monday. Based on the latest forecast, there may be enough cold
air at the surface initially for a period of freezing rain
Sunday night/Monday morning. Otherwise, temperatures currently
look to be warm enough to support all rain, and can expect
precip for the start of the new week.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

VFR conditions will continue across the TAF sites. An area of
light showers will move across the area during the morning hours,
but will dissipate and move offshore by mid-late morning. A brief
period of MVFR VSBYs will temporarily occur with some showers.
Winds will generally be out of the west- northwest around 5 knots
or less during the pre- dawn hours, then increase to 5-10 knots
during the day and into the evening hours.

A cold front will cross the area overnight tonight. The front
is expected to be dry, with mainly mid-high level cloudiness.
Winds will become gusty behind the front with northwest gusts
20-25 knots possible.

Outlook...
Wednesday through Thursday night...VFR. NW winds 15-20 KT with
25-30 KT gusts on Wednesday.

Friday...Sub-VFR conditions in -RA. A brief period of -FZRA
possible at KRDG/KABE Friday morning.

Saturday...VFR initially. MVFR or lower late in the afternoon
and at night in -RA.

&&

.MARINE...
Conditions will remain below Small Craft Advisory levels
through today. However, winds will increase overnight behind a
cold frontal passage to Small Craft Advisory levels, then Gale
force by daybreak Wednesday.

Outlook...
Wednesday...Strong NW flow, with Gales on the NJ ocean waters
and SCA conditions on DE ocean waters and DE Bay. Brief period
of Gales possible on DE ocean waters late Wednesday morning.

Wednesday night...Conditions subside to sub-SCA criteria.

Thursday...Sub-SCA conditions.

Friday...SCA conditions possible on the NJ ocean waters.

Saturday...Sub-SCA conditions.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Gale Warning from 6 AM to 11 PM EDT Wednesday for ANZ450>453.
     Small Craft Advisory from 6 AM Wednesday to 6 AM EDT Thursday
     for ANZ454-455.
     Small Craft Advisory from 6 AM Wednesday to 2 AM EDT Thursday
     for ANZ430-431.

&&

$$
Synopsis...MPS
Near Term...Robertson
Short Term...Robertson
Long Term...MPS
Aviation...Robertson/MPS
Marine...Robertson/MPS



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