Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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060
FXUS61 KPHI 170435
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1235 AM EDT Thu Oct 17 2019

.SYNOPSIS...
A coastal low pressure system will continue to intensify as it
moves northeast toward New England tonight. As this low moves through
the Canadian Maritimes on Friday, high pressure will approach our area
from the Ohio River Valley. This high is expected to move across the
Mid-Atlantic area Friday night, then offshore Saturday. An
area of low pressure may slip by to our south late Sunday and Monday,
followed by another frontal system by mid week.
&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...

1230 AM Update...Based on recent observations of winds gusting
in the 50-60 mph range along the coast, we upgraded to a High
Wind Warning for coastal NJ from Monmouth County southward and
also included Sussex Co in Delaware. Gusts should come down a
bit overnight then increase again for Thursday due to diurnal
mixing. Strictly speaking, while gusts to warning criteria (58
mph) may end up being more localized, think that with trees
still in full foliage expected impacts warrant the Warning.

Previous Discussion: The low is winding itself up and starting
to pull to the northeast tonight, taking with it the heavy
rainfall we saw through much of the area this afternoon and
evening.

As the low continues to lift, we will see the rain continue to
end from southwest to northeast and a fairly abrupt wind shift
from southeast to northwest. The low will continue to deepen as
it pulls away from the area and it looks like there will be less of a
chance we see good wrap-around rains. The exception will be
across portions of northeast Pennsylvania and northern New
Jersey where some wrap around and lake effect type showers come
down across the area in the west to northwest flow.

As the low continues to move past our area and lift into New England
this evening and overnight, it will significantly strengthen, which
will tighten the pressure gradient across our area. Also, with 45-55
mph above the surface, there will be the potential for 40-50 mph
wind gusts at the surface this evening and overnight. Winds
will not gust 45 to 50 mph the entire time, but will
consistently gust 35 to 40 mph, with peak gusts 45 to 50 mph at
times though the night, especially this evening once the low
passes by.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
The strong low pressure system will continue moving across New
England on Thursday while high pressure remains well to our west.
This will keep very strong pressure gradient across the area through
the day Thursday. 45-50 mph winds above the surface continue through
the day Thursday, which could continue to mix down to the surface.
Therefore the Wind Advisory will continue through the day Thursday.
Winds will not gust 45 to 50 mph the entire time, but will
consistently gust 35 to 40 mph, with peak gusts 45 to 50 mph at
times.

There will continue to be the chance of wrap around/lake effect type
showers across portions of northeast Pennsylvania and northern New
Jersey through the day Thursday as there will be some enhanced lift
do to elevated low level lapse rates and a couple of short
wave/vorticity impulses moving across the area combining with some
enhanced low-mid level moisture. PW values will be one-half to three-
quarters of an inch, so any precipitation will be light in nature
and fast moving.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Thursday night through Friday night...

Winds will diminish Thursday evening as the coastal low weakens
and moves eastward into the Canadian Maritimes. It will still
remain on the breezy side though with gusts upwards of 15 to 25
mph. Otherwise, variable cloud cover persists with lows mostly
in the 40s.

On Friday, weakening low continues to drift eastward through
Atlantic Canada while high pressure builds eastward towards the
east coast from the Ohio Valley. Expect lighter winds and more sunshine
compared to Thursday but it will still be on the breezy side
with seasonably cool max temperatures in the upper 50s to low 60s. The
high should build right over the region Friday night resulting in light
winds, clear skies, and good conditions for radiational cooling. As a result,
lows north of the I- 95 corridor are likely to dip into the 30s with possible
frost.

Saturday through Tuesday...

The weather pattern will remain progressive with a period of
continuing fair weather through Saturday. Then a low pressure system
may slip by to our south later Sunday and Monday followed by another
frontal system by midweek. Temperatures are expected to near to slightly
above normal through the period.

In terms of the details, high pressure sits over the area early
Saturday before slowly sliding off the coast by late day as the
upper level ridge crests along the east coast. This will result
in splendid fall conditions with sunshine, light winds, and
seasonable temperatures as highs will be mainly in the 60s.

High pressure with fair weather looks to dominate Saturday
night into Sunday. However, by Sunday afternoon, an area of warm advection
precip may affect southern and western parts of the forecast area as an area of
low pressure slips by further to our south late Sunday and Monday. The best
chances for precipitation with these systems appear to be south of the I-95
corridor. Another cold front is expected to move from west to east across
the area late Tuesday night and early Wednesday, bringing with it another round
of precipitation.

&&

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

Tonight...Improving conditions from MVFR/IFR to VFR tonight.
Only some light showers possible but chances remain fairly low
through the overnight period. There is a chance that some areas
may not lift above the upper end of MVFR and remain 2,500-3,000
feet overnight, this is especially true for ABE and RDG. High
confidence in improvement to VFR conditions, moderate on if any
2500-3000 ft cigs hang around past 03-06Z.

Winds have largely shifted to the northwest and are generally
10-15 knots with gusts around 20-30 knots. Wind gusts will
increase to 25-35 knots overnight, with peak gusts as much as 40
knots. High confidence in winds.

Thursday...Generally VFR conditions are expected through the day
Thursday. Some cigs around 2,500-3,000 feet are possible, mainly
at ABE and RDG. Moderate confidence.

Winds will remain west through the day Thursday and consistently
gusty around 25-35 knots, with peak gusts as much as 40 knots.
High confidence in winds.

OUTLOOK...

Thursday night...Ceilings may lower to MVFR during the evening
and overnight. Northwest wind gusting 25-30 knots early then
overnight. diminishing overnight. -High confidence in winds,
moderate confidence in ceilings.

Friday...Mainly VFR. Northwest wind gusts 15-25 knots.
-High confidence in winds, moderate confidence in ceilings.

Friday night-Saturday night...VFR conditions expected. Wind gusts
drop off during the evening. -High confidence.

Sunday and Monday...Mainly VFR conditions expected but periods
of MVFR or lower are possible. Easterly winds around 10 to 15
knots. Low confidence as a storm system may affect the region
Sunday through Monday.

&&

.MARINE...
Tonight-Thursday...Gale Warning in effect through Thursday for
all waters. Winds are already beginning to gust around 35 knots
for some areas and will increase everywhere through the
overnight and continuing through Thursday as low pressure
passes by our area and strengthens across New England.

OUTLOOK...
Thursday night...Gale Warning remains in effect. Conditions
lower below gale force late Thursday night.

Friday...Small Craft Advisory conditions early, before lowering
through the day..

Friday night-Saturday night...Conditions expected to be below
advisory levels.

Sunday and Monday...Gusty northeast winds and building seas. A
Small Craft Advisory may be needed.

&&

.TIDES/COASTAL FLOODING...
Southeast winds lingered long enough on the northern New Jersey
coast to allow for advisory-level flooding to occur in Monmouth
and Middlesex Counties. Have issued a coastal flood advisory
through midnight to account for this.

A coastal flood advisory continues for Kent County in Maryland
until 2 am as well, with flooding on the Chesapeake Bay
continuing for the next few hours before levels begin to recede.
As high tide has passed farther south, the advisory will be
allowed to expire at 10 pm for Queen Anne`s, Talbot, and
Caroline Counties.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Wind Advisory until 6 PM EDT this evening for PAZ054-055-
     060>062-070-071-101>106.
NJ...Wind Advisory until 6 PM EDT this evening for NJZ001-007>010-
     012-015>019-021.
     High Wind Warning until 6 PM EDT this evening for NJZ013-014-
     020-022>027.
DE...Wind Advisory until 6 PM EDT this evening for DEZ001-002.
     High Wind Warning until 6 PM EDT this evening for DEZ003-004.
MD...Wind Advisory until 6 PM EDT this evening for MDZ008-012-015-
     019-020.
MARINE...Gale Warning until 6 AM EDT Friday for ANZ430-431-450>455.

&&

$$
Synopsis...Miketta
Near Term...Fitzsimmons/Robertson
Short Term...Robertson/Meola
Long Term...Miketta
Aviation...Robertson/Meola/Miketta
Marine...Robertson/Meola/Miketta
Tides/Coastal Flooding...



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