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000
FXUS61 KPHI 230526
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
126 AM EDT Tue Apr 23 2024

.SYNOPSIS...
High pressure extending eastward from the Midwest to the Mid-
Atlantic will continue to build eastward toward the East Coast
today. A cold front will swing through our region on Wednesday,
followed by another area of high pressure pushing southeastward
from the Great Lakes Thursday and Friday. An approaching warm
front will bring a chance for some rain showers over the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Latest analysis depicts an elongated ridge of surface high
pressure extneding from the Southeast northeastward into
Atlantic Canada. Dry air, mostly clear skies and light winds
have promoted strong radiational cooling and we should have
fairly widespread frost early this morning, with frost and
freeze headlines remaining in effect until 9 AM. Otherwise, the
day should dawn sunny and calm.

Incoming system still over the central Plains and upper Midwest
will begin to spread some high clouds overhead today, but
otherwise, should be fairly sunny. With warm advection
developing ahead of the system on strengthening southerly flow,
expect highs to rise 5-10 degrees above yesterday`s readings,
which will feel quite nice after the chilly morning. Winds will
be a little gusty, perhaps up to 20 mph, but not much different
from yesterday.

The approaching system will further increase clouds with a
steady southerl flow tonight. This will help keep temps much
milder, with lows likely 10-15 degrees higher than this morning,
mostly 40s and low 50s. As the system gets closer late at night,
a few shower may move into the region, but overall not expecting
much, so kept overnight POPs in the slight chance to low-end
chance range.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
Clouds will return Wednesday as low pressure tracking across
Quebec and northern New England swings a cold front toward our
region. Model guidance has continued to advertise an earlier
initial frontal passage pushing offshore Wednesday morning.
Following an initial frontal passage early in the day, a
secondary front looks to approach by late day. Models are
indicating conditionally unstable conditions Wednesday
afternoon with this, and with the mid-level trough also
approaching, there may still be some pop up showers with even
some rumbles of thunder in the afternoon, especially northwest
of the Fall Line. And given fairly steep lapse rates in the low
and mid levels, some of these showers/storms could even contain
some hail and gusty winds. This system continues to look quite
moisture starved as well, without a tap to moisture from the
Gulf of Mexico. Rainfall amounts should be less than a quarter-
inch, and perhaps less than a tenth of an inch, for most
locations through Wednesday. Expect warm temperatures for the
most part on Wednesday, at least southeast of the Appalachians,
but accompanied by brisk northwest winds in the afternoon and
evening. Skies will clear as high pressure quickly builds
southeastward from the Great Lakes Wednesday night, across the
Northeast and Mid-Atlantic Thursday morning. If the atmosphere
can decouple and winds calm, that could set the stage for
another frosty morning in spots, especially the more favorable
locations like interior NJ and eastern PA north and west of the
Fall Line.

Thursday is shaping up to be mainly sunny and cooler under the
influence of high pressure with highs in the 50s to around 60.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Expect dry weather and mostly clear skies through Friday as strong
high pressure remains in control along the Mid-Atlantic coast.
Friday morning may see yet another frosty morning inland and outside
perhaps the most urban areas. Afternoon highs should then be in the
50s to low 60s. Models continue to struggle with the forecast
specifics regarding any rain over the weekend, but the general
synoptic set-up looks to be low pressure lifting across the upper
Great Lakes, with a warm front trying to cross the Appalachians.
That may bring some showers in, particularly across eastern PA at
some point over the weekend, but at this point am not expecting a
washout by any means. Sunday may finally see some high temperatures
rising above seasonal averages, possibly into the 70s. This looks to
continue into Monday with increasing shower/storm chances by late
day as a cold front starts to approach.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Through today...VFR. Light and variable winds early become
southerly 5-10 kts after daybreak. Gusts of 15-20 kts possible
later in the morning into the afternoon. High confidence.

Tonight...VFR. A few showers are possible late, but no
reductions in cigs or vsby expected before dawn Wednesday. Winds
southerly 5-10 kts. High confidence.

Outlook...

Tuesday Night - Wednesday...Potential for MVFR conditions at times,
as a cold front brings showers and a wind shift from southerly to
W/NW.

Thursday - Friday...VFR.

Saturday...Potential for stratus deck with MVFR cigs.

&&

.MARINE...
Today, winds start below advisory levels, but will increase
through the day and likely reach Small Craft Advisory levels on
the northern half of the New Jersey coastal waters, as well as
Delaware Bay. Therefore we have issued a Small Craft Advisory
for these areas. Tonight, the gusts on the bay diminish, but on
the oceans they should increase, so SCA`s expand to all ocean
zones after midnight. Seas will also build, reaching low-end
criteria by early Wednesday morning.

Outlook...

Wednesday... Small Craft Advisory conditions expected, at least
due to seas. SW winds around 15 kt gusting 20 to 25 kt,
shifting to the W/NW later in the day as a cold front swings
through. Seas 5 to 6 ft.

Thursday...SCA possible early in the morning due to lingering
elevated seas. Diminishing NE to E winds. Seas 3 to 5 ft.

Friday...Easterly winds 10-15 kt. Seas 2 to 3 ft.

Saturday...Southeast winds 10 t0 15 knots. Seas 3 to 4 feet.

&&

.FIRE WEATHER...
Though there will be some moisture advection with an approaching
system, the region will remain fairly dry today. Min RH values
across the region will be in the 25-35% range, with southerly
wind gusts in 15-25 mph range. As was done for Monday, a Special
Weather Statement for increased fire danger has been issued for
today.

&&

.TIDES/COASTAL FLOODING...
A prolonged period of southerly flow will develop during the
middle of the week ahead of a cold front that will push offshore
on Thursday. This is forecast to result in surge values rising
to around 1-2 feet above normal along Delaware Bay, the tidal
Delaware River, and Chesapeake Bay. With the full moon
occurring on Tuesday, astronomical tides will be maximized
around this time as well. This should result in some areas of
minor coastal flooding with the Wednesday night high tide,
although the extent and exact areas that may experience the most
impact remains unclear at this time.

Coastal flooding is not currently anticipated along the Atlantic
coast, except for potentially Barnegat Bay.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory until 9 AM EDT this morning for PAZ070-071-104-
     106.
     Freeze Warning until 9 AM EDT this morning for PAZ060>062-
     101>103-105.
NJ...Frost Advisory until 9 AM EDT this morning for NJZ016>019-023.
     Freeze Warning until 9 AM EDT this morning for NJZ001-007>010-
     012-013-015-020>022-027.
DE...Frost Advisory until 9 AM EDT this morning for DEZ001>003.
MD...Frost Advisory until 9 AM EDT this morning for MDZ012-015-019-
     020.
MARINE...Small Craft Advisory from 2 PM this afternoon to 8 PM EDT this
     evening for ANZ430-431.
     Small Craft Advisory from 4 PM this afternoon to 6 PM EDT
     Wednesday for ANZ450-451.
     Small Craft Advisory from midnight tonight to 6 PM EDT
     Wednesday for ANZ452>455.

&&

$$

SYNOPSIS...Fitzsimmons/RCM
NEAR TERM...RCM
SHORT TERM...AKL/Dodd/Fitzsimmons
LONG TERM...AKL/Dodd/Fitzsimmons
AVIATION...Fitzsimmons/RCM
MARINE...Fitzsimmons/RCM
FIRE WEATHER...Robertson/RCM
TIDES/COASTAL FLOODING...PHI