NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Mar 14, 12:46 PM EST, 14 minutes earlier.
Area forecast discussion, Mar 14, 12:46 PM EST, 14 minutes before
Area Forecast Discussion
National Weather Service Mount Holly NJ
146 PM EDT Sun Mar 14 2021
.SYNOPSIS...
A weak cold front will cross the region this morning, followed
by a second, stronger cold front this afternoon. High pressure
then builds in for Monday. A weak wave of low pressure
approaching from the west should pass south of our region
Tuesday into Wednesday. A stronger area of low pressure will
pass close by the region on Thursday or Friday with high
pressure returning next weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
The first of two cold fronts passed through the region this
morning, while a stronger secondary cold front is expected to
follow later this afternoon with a more noticeable temperature
drop. A few more clouds look possible with this secondary front,
though no precipitation is expected by any means given the very
dry airmass.
The main story for today will once again be wind and associated
fire weather concerns. A northwest wind of 20 to 25 MPH for
this afternoon will continue into this evening. Most of our
region should experience wind gusts in the 30 to 40 MPH range.
However, a somewhat tighter pressure gradient to our northeast
may result in wind gusts of 45 to 50 MPH in parts of northern
and central New Jersey, and in the elevated terrain of the
Poconos. A Wind Advisory remains in effect from noon until
midnight for the Pennsylvania counties of Carbon and Monroe, and
for the New Jersey counties of Sussex, Morris, Somerset,
Middlesex and Monmouth.
High temperatures today are forecast to range from the lower
and middle 40s on the Pocono Plateau to near 60 in southern
Delaware. Lows tonight are expected to fall into the teens up
north and the 20s elsewhere.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
By early Monday, high pressure will be building quickly into
the region from the northwest. Ongoing cold air advection
overnight and a tight pressure gradient will keep breezy
conditions in place through at least the first half of the day.
However, it won't be nearly as windy as Sunday with speeds of
10-15 mph and gusts of 20-25 mph, especially through the early
afternoon. Temperatures will be about 10-15 degrees colder than
Sunday as well, and combined with the wind and very low
dewpoints in the single digits and below 0 degrees will make it
feel quite uncomfortably cold and dry. A Red Flag Warning has
been issued and will remain in effect through Monday afternoon.
For more on the Fire weather concerns, please refer to the Fire
Weather discussion section below.
By late Monday, high pressure will be quickly centering itself
over the area for the overnight period, and winds will drop off
quickly by late afternoon and into the evening. Winds should be
mostly calm to light and variable at best overnight. With the
extremely dry airmass in place, temperatures should drop off
quickly as well with low temperatures largely in the 20s with
teens in the typical cold spots up north. Clouds will move in
overnight, but thinking that the dry air and calming winds will
allow for at least some decent radiational cooling beforehand.
By early Tuesday, an opening wave ejecting from the Southwest
will be located across the Great Lakes Region. A weakening
surface low will be moving across the Ohio Valley, which will
dissipate as another low forms off the Mid-Atlantic coast. The
general trend with this system has been weak and dry given the
extremely dry airmass it will be encountering as it moves into
the area, however a few showers are possible mainly Tuesday
through Tuesday night. QPF amounts will remain light, if any,
and I suspect the current dry streak of no measurable precip
will continue for most locations.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
By early Wednesday, a closed mid-level wave will be ejecting
northeastward from the southern Plains toward the Ohio Valley by
early Thursday. Low pressure at the surface will take a similar
path and progression as well. Into Thursday, the wave will
begin to weaken and open as it begins "feeling" the deep upper
ridging developing across the western CONUS. So the system
should become elongated, and as such the guidance isn't
completely in agreement on the details of this system at this
time. Nevertheless, it does appear probable that it will finally
bring much-needed precip to the region and end the dry streak
late Thursday.
The aforementioned ridging to the west will anchor a strong
cold high pressure system to our north though, which may end up
suppressing the low pressure system a bit by either weakening it
or pushing it a bit farther south. Given the cold high to the
north, mixed precipitation cannot be ruled out on the back end
of this system Thursday night or Friday. As the surface low
passes south of our area and offshore into Friday, a stronger
pressure gradient will develop as high pressure builds from the
northwest and thus a period of breezy conditions is probable.
The upper ridge axis should shift into the central CONUS into
Friday, pushing the Thursday system out to sea and allowing cold
high pressure to build into the region from the northwest into
the weekend. As a result, next weekend is looking dry and cooler
than normal.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Today...VFR under a mostly clear sky. Northwest wind from 15 to
20 knots with gusts around 30 knots into the afternoon. A few
gusts to 35 knots cannot be ruled out, but kept this out of the
TAFs at this point as they should remain relatively infrequent.
High confidence.
Tonight...VFR under a mostly clear sky. Northwest wind near 20
knots with gusts around 30 to 35 knots gradually diminishing to
10 to 15 knots with gusts around 20 knots. High confidence.
Outlook...
Monday...VFR. Northwesterly winds 10-15 kts with gusts up to 20
kts possible through around 21Z. High confidence.
Monday night...VFR with ceilings increasing in coverage and
lowering after 06Z. Winds light and variable. High confidence.
Tuesday through Tuesday night...Initially VFR with ceilings
continuing to lower. MVFR or IFR is possible by later in the day
with light mixing precip also possible at some terminals.
Southeasterly winds around 5 kts. Low confidence.
Wedensday through Wednesday night...Any ceiling restrictions
should improve to VFR after 12Z. Light and variable winds.
Moderate confidence.
Thursday through Thursday night...Ceiling and visibility
restrictions probable with precipitation and ceilings increasing
throughout the day. Winds easterly around 5 kts shifting
northerly and increasing to 10-15 kts after 00Z.
&&
.MARINE...
A secondary cold front will move southward through the region
this afternoon, increasing northwest wind to the coastal waters
of New Jersey and Delaware. Wind speeds are forecast to reach
25 to 30 knots as the afternoon progresses with gusts around 35
to 40 knots. Those wind speed will likely persist through much
of tonight. However, they may begin to diminish gradually toward
daybreak. A Gale Warning remains in effect for the coastal
waters of New Jersey and Delaware, and for Delaware Bay, for
this afternoon and tonight.
Outlook...
Monday...Northwesterly winds with gusts of 25-30 kts and seas
of 4-6 feet are expect through at least most of Monday morning,
then winds and seas will gradually diminish into the afternoon.
A Small Craft Advisory will likely continue through the morning.
Monday night through Wednesday night...Conditions are forecast
to remain below SCA criteria through this period with light
winds and seas 2-3 feet.
Thursday...Winds and seas will begin to build throughout the
day, and SCA conditions are probable by Thursday night.
&&
.FIRE WEATHER...
A Red Flag Warning is in effect.
Today will bring an increasing northwest wind. Sustained speeds
will likely reach 20 to 25 MPH this afternoon with gusts
generally in the 30 to 40 MPH range. Relative humidity values
are forecast to drop to around 20 percent.
The recent weather has caused fuel moisture levels to dry
significantly in our region. The only exceptions are the Pocono
Region and far northern New Jersey where the snow pack continues
to dwindle.
While the wind should diminish gradually overnight, relative
humidity levels may recover briefly only to about 35 to 40
percent.
The very dry conditions will continue across the forecast area
through Monday. Minimum relative humidity values are forecast to
be in the mid teens to around 20% with northwesterly winds
around 10-15 mph through the afternoon hours. Gusts of 15-25 mph
are also expected to last into the afternoon as well,
especially across portions of southeastern Pennsylvania and New
Jersey. Therefore, the Red Flag Warning was extended to cover
Monday as well.
Winds are forecast to drop off quickly by the late afternoon,
and thus the Red Flag Warning should be allowed to expire at
that time. Relative humidity values should recover into the 40s
and 50s Monday night with winds becoming light and variable.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Red Flag Warning until 5 PM EDT Monday for PAZ060>062-070-071-
101>106.
Wind Advisory until midnight EDT tonight for PAZ054-055.
NJ...Red Flag Warning until 5 PM EDT Monday for NJZ007>010-012>027.
Wind Advisory until midnight EDT tonight for NJZ001-008-010-
012>014.
DE...Red Flag Warning until 5 PM EDT Monday for DEZ001>004.
MD...Red Flag Warning until 5 PM EDT Monday for MDZ012-015-019-020.
MARINE...Gale Warning until 6 AM EDT Monday for ANZ430-431-450>455.
&&
Synopsis...O'Brien/Staarmann
Near Term...Davis/Iovino
Short Term...Staarmann
Long Term...Staarmann
Aviation...Davis/Iovino/Staarmann
Marine...Davis/Iovino/Staarmann
Fire Weather...WFO PHI