Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 020250
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
950 PM EST Mon Mar 1 2021

.SYNOPSIS...
An Arctic cold front moves through the region tonight, then
Canadian high pressure builds in from the west for Tuesday. The
high passes off the Mid-Atlantic coast Tuesday night, then
another cold front passes through the region on Wednesday. High
pressure builds in from the north for the end of the week and
weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
A few very light snow showers have made a return into the region
as remnant snow squalls are making a struggling journey across
the Appalachians. These are expected to remain on the light side
with current visibility observations staying above 5 miles.
Expanded the mention of these in the grids and added a tenth of
an inch of snowfall (which is being quite generous). Overall,
little impact expected with these through the evening as they
should wane a bit into the evening. Otherwise, temperatures
will continue to fall as colder air advects into the area.

The main headline for tonight continues to be the passage of a
secondary cold front that will bring strong winds and a piece of
arctic air to our area. The second front moves into our area
this evening and moves offshore tonight. This front should
remain dry as it moves through the area but as the winds start
to ramp up we could start to see some snow showers make their
way into our northwestern zones. A robust mid level low centered
to the northeast of our area will pull off to the east
overnight keeping the bulk of the energy to our north and east.
The upper jet cross the region and pushes offshore towards
daybreak. The limiting factor appears to be the surface based
instability as we won`t have much of that available due to the
shear amount of cloud cover that stuck around longer than
initially anticipated today. Therefore, as has been noted on
previous shifts, snow squalls seem unlikely but the possibility
of snow showers remains.

Winds have been a little weaker than forecast across a majority
of the region, but they should trend back upwards as a brief
lull appears to have left the region and a secondary cold front
and surface trough pivot southward across PA and NJ. While
timing isn`t great for ample mixing, there will be enough of a
push for the winds to gust between 40 to 50 mph with a few
higher gusts possible along the highest elevations and along the
ridges towards morning. The gradient really slackens off as we
head into Tuesday morning and we should see winds drop off
appreciably through the day. With saturated ground, it may not
take 40 to 45 mph winds to bring down trees but confidence isn`t
high enough to make any further expansions to the advisory as
the best dynamics remain just to our north.

A pocket of arctic air sneaks down behind the front, crossing
through the northeast and northern Mid-Atlantic overnight.
Temperatures will plummet into the upper teens to 20s, with
pockets of single digits possible in the higher terrain. While
the strong winds will prevent the temperatures from really
dropping off as much as they would on a light wind. clear sky
night, they will certainly make it feel much colder and more
like the single digits to mid teens through much of the area.
Wind chills will get down to around 0 to -10 across the southern
Poconos and northwestern New Jersey.

High pressure builds in from the west on Tuesday before sliding
to south and offshore Tuesday evening. Tuesday should be mostly
dry as the high builds in but with strong cold air advection in
place we may need to keep an eye on the potential for any lake
effect streamers to reach the forecast area. Best chances look
to be northern and western areas and during the morning hours
before the gradient really drops off. Temperatures on Tuesday
will be cold though we should see plenty of sunshine. Daytime
highs will remain in the 30s through much of the area with 20s
across the higher terrain, which is around 15 degrees colder
than they were today.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
High pressure will be centered off the Mid-Atlantic coast
Tuesday evening, then will drift out to sea Tuesday night.
Meanwhile, weak low pressure will pass from the Great Lakes into
northern New York state, and a stronger area of low pressure
develops over the eastern Gulf of Mexico. That southern stream
low will track east and move off the Southeast U.S. coast during
the day Wednesday. With weak high pressure building across the
Ohio Valley and Mid-Atlantic, the local area will remain clear
and dry.

With a good deal of sunshine and H8 temps from +1C to +3C,
Wednesday should be the warmest day of the week with highs in
the 40s across the northern zones and along the coasts, and in
the 50s across interior southern New Jersey, Delmarva, and the
Delaware Valley.

Another cold front passes through Wednesday night, and Canadian
high pressure builds in from the west. Strong CAA will be
underway. Lows generally in the upper 20s to low 30s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
A prolonged period of quiet, but cold, weather is on tap for the
first week of March.

Canadian high pressure digs into the Northern Plains and upper
Great Lakes starting on Thursday, and with a deep upper trough over
the Northeast, strong CAA will begin. Highs on Thursday will
generally be in the low to mid 40s, which is a few degrees below
normal. As the high builds closer, even colder air will surge to the
south and east, and highs will be in the 30s to near 40 for Friday
and Saturday, which is around 10 degrees below normal. Lows at night
will generally be in the teens and 20s. However, high pressure will
keep the region sunny and dry.

High pressure moves out to sea Saturday night, but the center of
another high builds in from the north and west for the end of the
weekend and start of the new week. Although temps should begin to
moderate, temperatures remain below normal.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Tonight...VFR. Windy. Northwest winds around 15 to 25 knots
with gusts to 40 kt. Gusts may begin to subside towards
daybreak. High confidence.

Tuesday...VFR. Northwest winds 10 to 15 kt with gusts around 25
to 30 knots, diminishing through the day. High confidence.

Outlook...

Tuesday night...VFR. SW winds less than 10 kt. High confidence.

Wednesday...VFR. W winds 10-15 kt during the day. High
confidence.

Wednesday night...VFR. NW winds less than 10 kt. High
confidence.

Thursday through Friday...VFR. NW winds 10-20 kt with
occasional gusts up to 25 kt during the day and around 10 kt at
night. Moderate confidence.

Saturday...VFR. W winds 10-15 kt. Moderate confidence.

&&

.MARINE...
Tonight through Tuesday...Gale Warnings are in effect for all
waters tonight into Tuesday. Northwest winds around 20 to 30
knots with gusts around 35 to 45 knots. A few gusts near storm
force are possible overnight. Light freezing spray is possible
late tonight mainly over the Atlantic coastal waters of northern
and central New Jersey.

Gales will end in the upper Delaware Bay in the early morning
on Tuesday and around mid day/early afternoon on the lower
Delaware Bay and ocean waters. Winds diminish through the day on
Tuesday, falling to 15 to 20 knots by the afternoon. Seas
building to 4 to 7 ft tonight then dropping down to 3 to 4 feet
by later Tuesday. Light freezing spray possible in the morning
mainly over the Atlantic coastal waters of northern and central
New Jersey. A Small Craft Advisory may be needed for a brief
period of time once the Gales are taken down though we should
start to lose the SCA gusts by late afternoon, especially over
the southern waters.

Outlook...

Tuesday night...SCA conditions possible, mainly on the ocean for 25
kt wind gusts.

Wednesday through Wednesday night...Sub-SCA conditions expected.

Thursday through Friday...SCA conditions for 25-30 kt wind
gusts on the ocean and Delaware Bay.

Saturday...Sub-SCA conditions possible.

&&

.HYDROLOGY...
Gradual rises continue this afternoon on many of our rivers in
the Raritan and Passaic basins in New Jersey. While the
Millstone River at Griggstown remains in minor flood stage, the
overall trend has been for the rises to not be as significant as
forecast as snowmelt was less than expected. Rain has ended and
while there will continue to be gradual river rises tonight
into Tuesday the latest forecast for Pine Brook on the Passaic
River now brings the point into action stage but below minor
flood stage as it crests tonight into Tuesday. All other
forecast points in the two river basins are anticipated to
remain below flood stage though water levels will be high.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Wind Advisory until 6 AM EST Tuesday for PAZ060>062-070-071-
     101>106.
     Wind Advisory until 10 AM EST Tuesday for PAZ054-055.
NJ...Wind Advisory until 6 AM EST Tuesday for NJZ001-007>010-
     012>027.
DE...Wind Advisory until 6 AM EST Tuesday for DEZ001-004.
MD...None.
MARINE...Gale Warning until 1 PM EST Tuesday for ANZ431-450>455.
     Gale Warning until 7 AM EST Tuesday for ANZ430.

&&

$$
Synopsis...MPS
Near Term...Davis/Meola
Short Term...MPS
Long Term...MPS
Aviation...Davis/Meola/MPS
Marine...Davis/Meola/MPS
Hydrology...WFO PHI



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