NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Mar 23, 8:31 PM EST, 29 minutes earlier.
Area forecast discussion, Mar 23, 8:31 PM EST, 29 minutes before
Area Forecast Discussion
National Weather Service Mount Holly NJ
931 PM EDT Wed Mar 23 2022
.SYNOPSIS...
A warm front will lift into our region tonight before stalling
over our region. A cold front will then sweep through the region
Thursday into Thursday evening. A fast moving low pressure
system will slide over our region this weekend. Cold air filters
in over the region in the wake of that low to start next week.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
850 PM Update...For the evening update we lowered temperatures
as the rain has helped to cool things. In fact temperatures are
near freezing in the higher elevations of the southern Poconos.
For this reason, I see an increasing potential for some freezing
rain tonight in the higher elevations of Monroe County (mainly
above 1800 feet). Accordingly, an SPS was issued highlighting
this. Precip should change to all rain later tonight as a warm
front lifts north. Previous discussion follows below.
A warm front will lift into the Mid Atlantic region tonight, and
likely stall out across southern New Jersey, Delaware, and eastern
Maryland as a couple of areas of low pressure move along the
boundary through Thursday and Thursday night. Meanwhile, several
short wave/vorticity impulses will move across the area, leading to
enhanced lift at times and creating occasional periods of
heavier/steadier rainfall. The first period of enhanced lift and
heavier rainfall will be this evening and overnight as the warm
front lifts into the area, north of the first low pressure system
moving along the boundary.The second will be during the morning
hours after daybreak into Thursday afternoon as the front stalls and
a short wave moves northeast near the coast. Finally, the third will
be during the afternoon and early evening Thursday ahead of the
second low pressure that moves across the area and pushed a
cold front across the area Thursday night. Once the cold front
moves across the area Thursday night, showers will end during
the overnight period.
Additionally, there will be some instability later tonight into
Thursday, especially across southeast Pennsylvania, central/southern
New Jersey, Delaware, and eastern Maryland, so there will be a
chance for a few scattered thunderstorms to be embedded with the
periods of rain.
Most precipitation is expected to be all rain, although there will
be a chance of sleet or freezing rain across portions of northeast
Pennsylvania and northern New Jersey overnight tonight if cold air
gets trapped at the surface long enough before the warmer air
continues to move into the area.
Model QPF are pretty similar with the heaviest precipitation
expected south and east of the I-95 corridor, with forecast amounts
of 1.5-2+ inches from the I-95 corridor eastward, with as much as 2-
3 inches possible for eastern portions of Delaware and New
Jersey. For areas north and west of the I-95 corridor, generally
1-1.5 inches is expected. While flash flooding and flooding of
larger rivers and creeks is not anticipated, the typical poor
drainage, urban, and localized stream/drainage ditch flooding
will be possible in some areas where the heaviest rain falls.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Mostly tranquil conditions are expected on Friday. A mid level
short wave trough may linger over the eastern Great Lakes, but
it looks like any precipitation will struggle to reach areas
downwind of the mountains in southeastern Pennsylvania. Though
we will be behind the initial cold front, the strongest cold air
advection appears to come with the secondary cold front on
Saturday, so Friday could be the last day with above normal
temperatures for a while.
The closed low that originally develops in the base of a mid
level negatively tilted trough over the upper mid west will
cross over our region Saturday and Saturday night, bringing a
secondary cold front and a brief window for additional chances
for precipitation. Most of the precipitation looks to come in
advance of the cold front, so precipitation should fall mostly
as rain, though some rain/snow showers will be possible if the
precipitation lingers long enough in the southern Poconos and
northwestern New Jersey.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The main story through this period will be the temperatures. In
the wake of the cold front, temperatures will be well below
normal. The growing season hasn't started yet, so no
frost/freeze headlines will be issued through this period, but
with the stretch of relatively warm weather recently, this cold
snap could be damaging to some early spring vegetation.
In general we should have dry conditions through this period,
though the mid level negatively tilted trough will still be over
our region especially Sunday into Monday, resulting in synoptic
scale lift. However, moisture will be very limited, so do not
expect significant precipitation. A complex low pressure system
may be approaching the region Tuesday night, but much of the
latest guidance has trended slower with this system, so it may
not arrive until Wednesday or Wednesday night. Regardless of
when it arrives, this looks to be the next opportunity for a
slight warming trend and chances for precipitation.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...MVFR conditions early this evening lowering to IFR later
this evening through the overnight hours with periods of moderate to
heavy rainfall possible. There is also a chance of thunderstorms,
mainly south of PHL. East winds around 10 knots with gusts 15-20
knots. High confidence in restrictions, lower confidence on
specific timing.
Thursday...IFR conditions continue for all areas with periods of
rain. Winds will generally be northeast for most TAF sites except
southeast at MIV and ACY. Wind speeds 5-10 knots with gusts 15 to 20
knots. High confidence in lower conditions, lower confidence in
winds.
Thursday night...MVFR and IFR conditions during the evening
hours with showers ending, improving to VFR overnight. Northeast
and southeast winds shift to the west to northwest overnight as
a cold front shifts across the area. High confidence in lower
conditions early, and improvement to VFR late, lower confidence
on specific timing.
Outlook...
Friday...Mostly VFR conditions, though there is a slight chance
for showers at KABE during the day which could result in
temporary MVFR conditions. Westerly wind 10 to 15 kt with gusts
to 20 kt during the day, becoming southwesterly less than 10 kt
Friday night. Moderate confidence.
Saturday...Predominantly VFR, though rain showers could result
in periods of MVFR conditions, especially during the day on
Saturday. Southwesterly winds 5 to 15 kt, becoming northwesterly
5 to 15 kt late in the day and into Saturday night. Moderate
confidence on the overall pattern, but low confidence on timing
details.
Sunday...Mostly VFR conditions. Northwesterly winds 10 to 20kt
decreasing to around 10 kt Sunday night. Moderate confidence.
Monday...Mostly VFR conditions. Northwesterly winds 15 to 20kt.
Moderate confidence.
&&
.MARINE...
East winds continue to increase this evening and we've upgraded
the Small Craft Advisory to a Gale Warning for our northern two
ocean zones adjacent to the northern NJ coast. This is in effect
until 10z. Wind gusts to 35 knots are likely by late this
evening lasting into the overnight. Otherwise, Small Craft
Advisory conditions will remain tonight through Thursday night
for the Atlantic Ocean zones. The Small Craft Advisory will
continue tonight for Delaware Bay, but will end around daybreak
Thursday for the upper portions of Delaware Bay and end by
midday for the lower portions of Delaware Bay. Winds may
increase again later in the night Thursday, potentially reaching
advisory levels again.
Outlook...
Friday through Saturday...once seas subside below 5 feet on
Friday, winds and seas should stay below SCA criteria.
Saturday night and Sunday...Northwesterly winds may increase
above 25 kt on all area waters late Saturday night into Sunday.
Seas on the coastal waters may approach 5 feet as well.
Monday...Northwesterly winds above 25 kt on all area waters. Seas on
the coastal waters may exceed 5 feet.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ452>455.
Gale Warning until 6 AM EDT Thursday for ANZ450-451.
Small Craft Advisory until 6 AM EDT Thursday for ANZ430.
Small Craft Advisory until noon EDT Thursday for ANZ431.
&&
Synopsis...Johnson
Near Term...Fitzsimmons/Robertson
Short Term...Franklin/Iovino
Long Term...Franklin/Johnson
Aviation...Fitzsimmons/Franklin/Robertson
Marine...Fitzsimmons/Franklin/Robertson