Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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411
FXUS61 KPHI 220435
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1235 AM EDT Mon Apr 22 2019

.SYNOPSIS...
A surface low off the Carolina coast will lift slowly northward
through Monday, reaching the vicinity of Cape Cod Monday night
and progressing off the New England coast on Tuesday. Low
pressure passing north of the region will drag a cold front
through the Northeast and Mid-Atlantic Tuesday night. High
pressure returns for the mid-week period. Another storm system
may affect the region on Friday, followed by high pressure for
next weekend.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
930 pm update: No updates to the forecast were required.

630 pm update: Minor changes are being made to the forecast
overnight. Winds are lowering a little faster than forecast, so
adjusted speeds downward this evening. Additionally, lowered
PoPs by about ten percent everywhere through the overnight
hours, with sparse coverage generally expected (if even that)
and light or (more likely) non-measurable precipitation wherever
it occurs. Chances increase again late, generally in coastal NJ
and Delmarva, as a surface low developing off the Carolina coast
trudges northward slowly.

Previous discussion...

An upper level cutoff low centered over the mid-Atlantic states
will continue a very slow E to SE progression overnight.
Meanwhile, a weak low is expected to develop along a surface
trough just off the Virginia coast Monday morning before moving
NE. A southerly flow generally less than 10 MPH across the area
will become NE toward morning. Clouds could thin out early, then
increase again toward morning when scattered showers are again
possible, especially closer to the coast. Temperatures are
expected to bottom out in the mid-40s across the north, and
around the 50 degree mark across the south, which is a few
degrees above normal for this time of year.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
630 pm update: Made some adjustments to the forecast for Monday.
The biggest change was to increase winds/gusts about 5 to 10
mph during the day as a surface low approaches the area. North
to northwest flow upstream of the low should increase as the
pressure gradient tightens on the western side of the low.
Additionally, fine-tuned PoPs, making them about 10-20 percent
lower in the western CWA while maintaining higher PoPs closer to
the coast, in closer proximity to the stronger lift provided by
the low off the coast.

Previous discussion...

Weak low pressure moving NE well off the NJ coast, phased with its
associated upper level low, will produce clouds and occasional
spotty showers throughout the region into the afternoon hours. With
limited moisture, rainfall totals should be on the light side,
generally around one-quarter inch or less, and many locations may
see no rain at all. A north to northeast flow will become NW later
in the day as the low continues to move slowly northeast, bringing
in drier air to the region. Temperatures are expected to peak in the
upper 60s and low 70s, about normal for this time of year.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Showers taper off Monday night as low pressure over New England
moves out to sea. Surface high pressure builds in from the
west, and will center itself over the Southeast coast on
Tuesday. A ridge extending from the high will extend into New
Jersey Tuesday morning, and moves offshore in the afternoon.
West to southwest flow will usher a warm airmass into the region
with highs some 15 degrees above normal, topping off in the 70s
to around 80. Afternoon seabreezes will result in cooler temps
near the coasts.

Late in the day, low pressure will pass through the Great Lakes
and towards eastern Canada. As it does, it drags a cold front
towards western New York and western Pennsylvania. Some showers
may move into the southern Poconos, northern New Jersey, and the
Lehigh Valley late in the day, but the bulk of the activity
holds off until Tuesday night. Cannot rule out a couple of
rumbles of thunder across the northern zones in the evening as
some mid-level shortwave energy passes north of the region, but
not expecting much in the way of precip Tuesday night, generally
less than 1/10 inch QPF.

Cold front moves offshore Wednesday morning, and then high
pressure builds in from the north and west. Highs on Wednesday
will be some 5- 10 degrees cooler than Tuesday.

During this time, a storm system will organize and develop over
the central United States, and as low pressure looks to
intensify over the Ohio Valley Thursday night. The low passes
through the Northeast and Mid-Atlantic on Friday. For now, will
keep PoPs capped at high chance, as this is several days out.

High pressure then returns for next weekend.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...Mainly VFR with CIGs between 5-10 kft, though periods
without CIGs are also expected, especially at ACY/MIV. Should
see cloud bases lower somewhat toward morning. Additionally,
chances for showers increase late, especially near the coast,
though impacts at the terminals are not expected. Light/variable
winds. Moderate confidence.

Monday...Mainly VFR, though some brief periods of MVFR may occur
near any showers (greatest chances near the coast). So far,
chances of showers and MVFR appear too low for TAF inclusion.
Winds becoming north or northwest around 10 kts, possibly with
some gusts during the afternoon. Moderate confidence.

OUTLOOK...

Monday night...Mainly VFR. SHRA taper off in the evening. NW
winds less than 10 kt.

Tuesday...VFR. West winds 5-10 kt. Afternoon seabreezes likely
for KACY/KMIV.

Tuesday night through Wednesday...Mainly VFR, but brief MVFR
conditions possible in scattered SHRA. SW winds 5-10 kt Tuesday
night, becoming NW 10-15 kt with gusts up to 20 kt on Wednesday.

Thursday...VFR. Light west winds.

Friday...MVFR or lower in SHRA. Light SW winds.

&&

.MARINE...
Overnight...SCA dropped for the srn NJ and DE ocean waters with
seas now less than 5 ft at 44009. Scattered showers late.

Monday...SCA through the day on the central and nrn NJ ocean
waters, but seas will gradually diminish late. Scattered
showers are expected.

OUTLOOK...
Monday night through Friday...Sub-SCA conditions expected most
of the upcoming week. The next chance for SCA conditions will be
on Friday.

&&

.EQUIPMENT...
KDIX remains inoperable until further notice.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for
     ANZ450>452.

&&

$$
Synopsis...CMS/MPS
Near Term...CMS/Miketta
Short Term...CMS/Miketta
Long Term...MPS
Aviation...CMS/MPS
Marine...Miketta/MPS/PO
Equipment...



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