NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Feb 5, 9:02 PM EST, 4 hours 58 minutes earlier.
Area forecast discussion, Feb 5, 9:02 PM EST, 4 hours 58 minutes before
Area Forecast Discussion
National Weather Service Mount Holly NJ
902 PM EST Sun Feb 5 2023
.SYNOPSIS...
A weak cold front is expected to arrive early on Monday. High
pressure builds in Tuesday before a fast moving trough crosses
the northeast Tuesday night. A low pressure system is expected
to progress from the southern Great Plains to the Great Lakes
Region during the later half of the week, bringing a chance for
precipitation to our region. Right on the heels of that system,
another low is expected to lift out of the mid Mississippi
Valley to the Mid Atlantic next weekend.
&&
.NEAR TERM /THROUGH MONDAY/...
As we go through the evening, a disturbance to our south will
move northward and begin to interact with an upper level trough
approaching from our west. This will result in a low pressure
system eventually developing well off the coast by morning. As
far as sensible weather impacts in our area, the western edge of
some rainfall with the system looks to brush right along the
coast as the system moves northward and develops offshore. This
may bring some light rain this evening into the first part of
the overnight right along Atlantic coastal areas of DE and NJ
but amounts should be minimal with this moving offshore
overnight. Otherwise, expect considerable mid and high level
cloudiness over the area tonight but it should be relatively
mild in terms of overnight lows for this time of year with lows
mainly in the 30s.
For Monday, low pressure will deepen well offshore while high
pressure builds in to our north and west over Ontario and
Quebec. This will result in blustery northerly winds of around
15 gusting 20 to 25 mph at times. Expect highs mainly ranging
from the 40s north to the low 50s south, except a bit cooler
over the southern Poconos. Also expect there will be a fair
amount of strato cu around for a time around midday into the
afternoon near and north of the urban corridor.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
Surface high pressure supported by upper level ridging builds
into the region Monday night and into Tuesday, providing a
mostly dry period through Tuesday afternoon. Mostly clear skies
Monday night will allow for good radiational cooling with
overnight lows dropping into the 20s. On Tuesday, surface high
pressure remains in control, but a vertically stacked trough
will be progressing across southern Canada and the northern tier
of the US. While the main trough axis is expected to remain
just north of the region, along with much of the moisture, we
can expect some mid to high level clouds developing through the
day on Tuesday before the system squeezes by to our north
Tuesday evening and exiting Tuesday night. With the main area of
lift associated with this trough staying well north of our
region, this should be a mostly dry period for us. However,
there has been a consistent signal between some of the
deterministic models with the southern extent of precip getting
as far south as roughly the I-80 corridor. Therefore, have
included a slight chance of rain in these areas Tuesday evening,
but any rain should be light and brief. Highs Tuesday are
expected in the mid 40s to low 50s with upper 30s across the
Pocono Plateau. Overnight lows Tuesday night will only cool down
to the mid to upper 30s with low 30s across the Poconos due to
expected cloud coverage inhibiting radiational cooling.
High pressure returns briefly Wednesday. Mostly clear skies and
mild temperatures in the afternoon, warming up to the low- to-
upper 50s with mid 40s in the Poconos.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Overview: Two systems we are watching through this period.
First, a low passing to our W and NW Thursday into Friday brings
a chance of rain. The next system is forecast to take a track
closer to our region at the beginning of next weekend. This may
bring another chance for precip mostly centered around Saturday.
Details:
Wednesday night into Friday...Global guidance continues to show
better agreement on overall track with our first system mid
week, though some timing differences still remain. Regardless,
the general evolution of this first system is beginning to come
into better focus. As a southern stream mid and upper level
trough crosses over to the lee side of the Rockies, cyclogenesis
is expected to result in a low developing on the stalled front
over the ArkLaTx region before it lifts northeastward along the
front towards the central Great Lakes region. As the low lifts
northward across the Mississippi River Valley, a warm front
ahead of the system will lift across the area beginning early
Thursday morning which may give us an initial round of rain,
mainly across eastern PA. Rainfall will then continue into the
daytime hours Thursday as warm air advection and moisture
advection surge ahead of the approaching cold front. Latest
guidance is in better agreement that the heaviest precipitation
will fall during the day on Thursday before beginning to taper
off Thursday night and into Friday morning. With strong warm air
advection ahead of the cold front, we could see temperatures on
Thursday climb into the 50s and low 60s during the day. Cold
front will push through sometime Thursday evening through early
Friday morning, allowing the rain to taper off, but temperature
gradient behind the front will not be terribly impressive.
Overnight lows will only dip into the 40s.
Friday and Saturday...Some weak ridging behind the front will
allow for a brief dry period Friday before the next storm system
begins to take shape. Model guidance continues to disagree with
timing and evolution of this second system this far out.
Generally speaking though, a large positively tilted trough will
dig southward across the length of the eastern US Friday into
Saturday, developing a primary coastal low off the Southeastern
US coastline and a secondary low over the Ohio River Valley.
Assuming guidance doesn't trend so far south with the track of
this low that our region is NW of the precipitation shield, this
should mean another chance for precipitation in our region
beginning sometime late Friday and into Saturday. What makes
this system potentially unique (at least for this winter), is
the current forecast track would actually put our region in the
cold sector of the system. That being said, that doesn't
necessarily mean wintry precipitation will result, especially if
the timing is during the day. At this point, have a mention of
rain for most places with the exception of the higher terrain of
NW NJ and the southern Poconos.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Overnight...VFR ceilings. South to southwest wind 4 to 8 knots,
becoming variable 6 knots or less. High confidence.
Monday...VFR with varying cloud cover. Northwest wind
increasing to 10 to 15 knots with gusts of 20 to 25 knots. High
confidence.
Monday night...VFR under a mostly clear sky. Northwest to north
wind 5 to 10 knots, becoming variable 6 knots or less. High
confidence.
Outlook...
Tuesday through Tuesday night...VFR. SE/S winds of 10 kts with
gusts around 15 kts, becoming SW by Tuesday night. Moderate
confidence.
Wednesday and Wednesday night...VFR. W winds of 10-15 kts
becoming light and variable overnight. Low confidence.
Thursday and Thursday night...MVFR or even IFR conditions
possible as rain and lower ceilings move in. S and SW winds
10-20 kts with gusts up to 25 kts. Low confidence.
Friday and Friday night...Sub-VFR conditions possible during
the day, becoming more likely Friday night. W winds 10-15 kts
turning N at night. Low confidence.
&&
.MARINE...
We have cancelled Sunday's Small Craft Advisory and replaced it
with a new one for Monday.
The winds and seas will diminish overnight before increasing
out of the north/northwest Monday morning at around 15 to 20
gusting up to 25 or 30 knots. Seas should be 3-4 feet overnight
before increasing once again to 4-5 feet Monday.
Outlook...
Monday night...NNW winds start out strong in the evening,
gusting around 20-25 kts, before diminish overnight to 10-15
kts. Seas 2-4 feet.
Tuesday through Wednesday...SW winds are expected to increase
through the day on Tuesday, and seas will subsequently increase
as well, with SCA conditions possible on the Atlantic coastal
waters by Tuesday night. Winds and seas will gradually diminish
below SCA criteria during the day on Wednesday. On the Delaware
Bay, winds and waves should stay below SCA conditions.
Thursday and Thursday night...S winds and seas could build to
SCA criteria by Thursday afternoon or Thursday night.
Friday and Friday night...W wind around 10-15 kts during the
day turns N Friday evening and gradually increases to gusts
around 20 kts overnight, nearing SCA conditions.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 10 AM to 7 PM EST Monday for ANZ430-
431-454-455.
Small Craft Advisory from 10 AM to 10 PM EST Monday for
ANZ450>453.
&&
SYNOPSIS...Johnson
NEAR TERM...Fitzsimmons
SHORT TERM...Johnson/MJL
LONG TERM...Johnson/MJL
AVIATION...Deal/Iovino/Johnson/MJL
MARINE...Deal/Fitzsimmons/Johnson/MJL