NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Mar 3, 10:47 PM EST, 2 hours 13 minutes earlier.
Area forecast discussion, Mar 3, 10:47 PM EST, 2 hours 13 minutes before
Area Forecast Discussion
National Weather Service Mount Holly NJ
1047 PM EST Fri Mar 3 2023
.SYNOPSIS...
Strong low pressure tracks to near Lake Erie late tonight then
weakens as it moves across central New York. Meanwhile, a new low
develops later tonight across northern Delmarva then strengthens as
it tracks northeastward through Saturday morning. High pressure will
then gradually build across the region Sunday and Monday before
another system moves through later Monday night into Tuesday
morning. Strong high pressure centered in central Canada will then
start to extend toward our area for Wednesday into Friday.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
Impactful Storm expected for later today into tonight...
The big weather story is still the storm system expected to
impact the area through tonight. Overall, the forecast remains
on track so few changes have been made. As of late this
evening, a potent area of low pressure was moving NE centered
over Ohio, with a secondary low beginning to form to the
southeast over North Carolina and Virginia. The warm front with
this system extends east from the low towards the Virginias
with precip north of this feature continuing to move into the
mid Atlantic. In terms of what's expected for our area with the
storm, biggest concern is coastal flooding and it could be quite
significant along the NJ coast. This is detailed in the coastal
flooding section below. The flooding will be driven by strong
E/SE winds that will ramp up for tonight and for this reason we
also have Wind Advisories near the coast. Other threats will be
localized freshwater flooding from heavy rain and wintry precip
expected mainly over the southern Poconos where Winter Weather
Advisories remain in effect for Carbon and Monroe Counties.
As we head into tonight, precip will intensify across the area
as the low approaches and the associated warm front starts to
lift northward. The main concern for wintry weather will be
near/north of the I-80 corridor. These areas saw a wintry mix
of snow/sleet earlier that has largely transitioned to freezing
rain this evening. Mixed precipitation mainly consisting of
freezing rain is expected to continue through much of the
overnight hours until the passage of the low. Otherwise, expect
rain, heavy at times, farther south with winds ramping up along
the coast where Wind Advisories remain in effect. Generally
expect E/SE winds gusting 40 to 50 mph near the coast but it's
possible there could be more localized gusts of 50 to 60 mph in
any heavier bands of rain and/or embedded thunderstorms as
conditions are favorable for elevated convection. This is due to
the fact that there will be a very strong LLJ moving in near
925 mb of 60-70+ knots. In fact guidance has trended stronger
with this feature. The lowest levels being fairly stable should
at least limit there being widespread severe winds. The strong
LLJ will also be pumping in very warm, moist air enhancing the
heavy rain threat and we still have concerns there could be
localized freshwater flooding that occurs, especially around the
urban corridor. So all in all, a very stormy night.
By the overnight period, as the primary low tracks towards the
lower Great Lakes the secondary low will continue to develop
closer to the coast and basically track right across the area as
it moves from Delmarva through NJ then off towards Long Island
by 12z Saturday. This should result in precip finally shutting
down late tonight as the low passes by. By this time expect a
generally 1 to 1.5 inches of rainfall for much of the area with
localized amounts around 2 inches possible. Farther north,
thinking is still that snow/sleet accumulation for the southern
Poconos should be limited to at most a couple inches with the
greater concern being the potential for around a tenth of an
inch or so of ice accretion, mainly for elevations above 1000
ft. However even these higher elevation areas may see a change
to all rain at the peak of the storm as the low moves through.
The low departs to the east for Saturday with precip basically
done by this time but a growing concern we have is that there
will be strong NW winds in its wake due to a tight pressure
gradient, strong winds aloft, and steepening low level lapse
rates. As a result, the Wind Advisory was continued until 3 PM
tomorrow for southern NJ coastal areas with advisory now in
effect for the day tomorrow farther north along the DE Bay, our
eastern MD counties and then into portions of SE PA. Generally
expect winds gusting 40 to 50 mph in the advisory areas for
Saturday and 30 to 40 mph elsewhere. Otherwise, precip winds
down to just a few rain/snow showers (mainly over NE PA into NW
NJ) with considerable cloud cover persisting. Highs mainly in
the upper 40s to low 50s.
The weather finally quiets down for Saturday night with high
pressure building in. Expect lows ranging from mid 20s north to
mid 30s south.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
An upper-level trough is forecast to be shifting farther east and
away from the Northeast during Sunday. As some ridging aloft shifts
eastward with time, sprawling surface high pressure is forecast to
build over our area during Sunday. The axis of this surface high
will be to our west for much of the day Sunday, therefore a
northwesterly breeze will continue before diminishing at night. Some
stratocumulus clouds should be in place, with this tending be the
most widespread near and north of I-78. Temperatures are anticipated
to top out into the low to mid 50s for much of the area (cooler in
the higher elevations).
As we go through Monday, the ridge axis aloft is forecast to slide
across our area and then offshore taking surface high pressure with
it. An upper-level trough sliding across the Midwest and Great Lakes
will quickly translate eastward through Monday night. Low-level warm
air advection will increase ahead of this system and the surface low
may end up tracking right over our area, especially the northern
areas, late Monday night. The track of this low will determine the
extent of the precipitation, with the main overrunning occurring
along and north of the surface low track. Placed the highest PoPs
across the far northern areas as a result Monday night, with farther
south getting more into the warm sector and perhaps having it more
showery (less coverage). Before then, clouds will start to increase
later Monday and especially Monday evening as the system arrives.
Depending on the thermal profiles and the track of the surface low,
some wintry precipitation will probably occur across the far
northern areas for a time. Temperatures may end up becoming steady
or even rising some Monday night ahead of the surface low and with
the warm front gradually shifting northward.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Summary...Milder to start, then temperatures look to be near or a
little below average along with generally drier conditions.
The next storm system however may approach Friday.
Synoptic Overview...A strong upper-level trough is forecast to be
tracking just to our north Tuesday. This drives surface low pressure
nearby, with much of our area into the warm sector. A cold front
then shifts offshore during Tuesday morning. An upper-level trough
is forecast to lingering across New England through Wednesday, then
some ridging starts to build closer Thursday. The ridge axis may
then slide across our area on Friday as a potentially strong upper-
level trough organizes across the Plains. The late week trough
amplification and location is less certain and this will have
implications on cyclogenesis which could be toward our area.
For Tuesday...A quick moving upper-level trough is forecast to slide
across the Northeast in the morning. Surface low pressure tracks
across mostly our northern areas. The steadiest precipitation across
our far northern areas should be ending early Tuesday morning, then
drying starts to overspread our area. Cold air advection starts to
increase in the wake of the system and with strong high pressure
starting to extend into the Ohio Valley, a tight pressure gradient
will be in place. Decent vertical mixing should result in a gusty
west to northwest wind during the day, then diminishing some at
night. Temperatures will start off on the milder side, then start to
drop off by late afternoon. It then turns colder at night with
temperatures dropping down into the mid/upper 20s to low 30s
overnight.
For Wednesday and Thursday...Our region is forecast to remain on the
western side of a gradually departing upper-level trough. This will
maintain a northwesterly flow aloft. This looks to be generally a
dry flow, however some lake effect off the eastern Great Lakes may
send a few showers toward the Pocono region. Otherwise, daytime
heating may result in some additional cloudiness during each
afternoon. With strong surface high pressure centered in central
Canada but extending down through the Ohio Valley, a tightened
pressure gradient looks to be in place and this should keep a
notable breeze going during each day. Temperatures should tend to
favor near or a little below average.
For Friday...The upper-level flow may amplify and start to favor a
trough approaching the East Coast. There is quite a bit of
uncertainty regarding the timing and amplification of this trough,
which will determine where an associated surface low goes. Given the
spread in guidance and that this is a week away, opted to go with
the National Blend of Models (NBM) guidance. This brings in some low
PoPs from the southwest, and kept the precipitation types
simplified.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...IFR conditions likely. Moderate to heavy rain at
times between 00Z-08Z. Mixed precipitation at KRDG/KABE will
change to all rain by 02Z. Lingering light showers possible for
the remainder of the night. Easterly winds around 10-20 kts with
gusts to around 30 kts. KRDG/KMIV and especially KACY could see
gusts to 35-40 kts. Winds will shift late in the night as an
area of low pressure moves overhead and off to the northeast.
Expect a wind shift to the west between 08z-12z. With a strong
low- level jet overhead tonight, some LLWS is possible at all
terminals. High confidence in restrictions, moderate confidence
on the overall evolution.
Saturday...MVFR conditions possibly lingering early, although a
trend to VFR is expected everywhere by 18Z. Westerly winds near
20 kts, with gusts up to 35 kts. Winds shifting northwest around
18Z. Moderate confidence.
Outlook...
Sunday...VFR. Northwest winds 10-15 knots, diminishing to 5 knots
or less at night. High confidence.
Monday...VFR during the day, then clouds lower some at night with a
chance for some rain late at night. Northwest to west winds 5-10
knots, becoming southerly at night. Low confidence.
Tuesday...Sub-VFR conditions with some rain possible, mainly in the
morning. West-northwest winds 10-20 knots with gusts up to 30 knots.
Low confidence.
Wednesday...VFR. Northwest winds 10-15 knots with gusts to around 25
knots, diminishing at night. Moderate confidence.
&&
.MARINE...
Gale Warning remains in effect for all marine zones. Gusts
around 40- 45 kts are expected with seas building as the night
goes on. Seas around 6 to 11 feet are anticipated. Wind
direction will be out of the east/southeast, coming around to
the south/southwest by late tonight and then westerly Saturday
with Gales continuing for all but our far northern zone.
Conditions should finally abate Saturday night.
Outlook...
Sunday and Monday...The conditions are anticipated to be below Small
Craft Advisory criteria.
Tuesday and Wednesday...Small Craft Advisory probable due to gusty
winds and building seas. The conditions should improve later
Wednesday.
&&
.TIDES/COASTAL FLOODING...
Will go ahead and update the tide level forecast based on the
P-ETSS 90%. This brings the highest forecast values down by a
foot or so, but this also does not change any of the categories.
Still expecting Moderate coastal flooding for coastal areas of
Middlesex, Monmouth, and Ocean counties, but the threat for
Major coastal flooding has diminished. This is possibly due to
the strongest winds diminishing and beginning to turn to the
north about an hour or two prior to high tide as the low passes
overhead. Will not make any headline changes. A Coastal Flood
Warning remains in effect for those 3 counties. Water may be
slow to depart from Barnegat Bay, and coastal flooding may
persist into Saturday afternoon and evening.
Widespread minor flooding is forecast elsewhere across Atlantic
coastal New Jersey as well as the Delaware Bay coasts in New
Jersey and Delaware and tidal Delaware River. Along Delaware Bay
in Cumberland and Kent Counties, tidal flooding has the
potential to locally reach near moderate flood stage. Spotty
minor coastal flooding is possible elsewhere along Atlantic
coastal Delaware, and the eastern shore of Chesapeake Bay.
Coastal Flood Warning remains in effect for the high tide early
Saturday morning for Middlesex, Monmouth, Ocean, and southeast
Burlington Counties, from 3 AM through 11 AM Saturday. Coastal
Flood Advisories remain in effect as previously issued for the
Delaware Bay and tidal Delaware River where widespread minor
coastal flooding is expected for the high tide Saturday morning.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Wind Advisory from 7 AM to 3 PM EST Saturday for PAZ070-101-
102.
Coastal Flood Advisory from 9 AM to 2 PM EST Saturday for
PAZ070-071-106.
Winter Weather Advisory until 4 AM EST Saturday for PAZ054-055.
NJ...Coastal Flood Advisory from 7 AM to 11 AM EST Saturday for
NJZ016.
Wind Advisory from 7 AM to 3 PM EST Saturday for NJZ016-017-
021.
Coastal Flood Advisory from 3 AM to 11 AM EST Saturday for
NJZ021>025.
Wind Advisory until 3 PM EST Saturday for NJZ022>025.
Coastal Flood Warning from 3 AM to 11 AM EST Saturday for
NJZ012>014-020-026-027.
Wind Advisory until 4 AM EST Saturday for NJZ013-014-020-026-
027.
Coastal Flood Advisory from 9 AM to 2 PM EST Saturday for
NJZ015-017>019.
DE...Coastal Flood Advisory from 7 AM to 11 AM EST Saturday for
DEZ001.
Wind Advisory from 7 AM to 3 PM EST Saturday for DEZ001-002.
Coastal Flood Advisory from 3 AM to 11 AM EST Saturday for
DEZ002.
Wind Advisory until 3 PM EST Saturday for DEZ003-004.
MD...Wind Advisory from 7 AM to 3 PM EST Saturday for MDZ012-015-
019-020.
MARINE...Gale Warning until 3 PM EST Saturday for ANZ430-431-451>455.
Gale Warning until 6 AM EST Saturday for ANZ450.
&&
SYNOPSIS...Gorse
NEAR TERM...AKL/Fitzsimmons/Hoeflich
SHORT TERM...Gorse
LONG TERM...Gorse
AVIATION...AKL/Gorse/Hoeflich/Staarmann
MARINE...Fitzsimmons/Gorse
TIDES/COASTAL FLOODING...