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000
FXUS61 KPHI 191319
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
919 AM EDT Fri Apr 19 2024

.SYNOPSIS...
High pressure near Nova Scotia will continue to shift east today.
Meanwhile, an area of low pressure will track through southern
Canada as a trailing cold front sweeps across our area tonight. The
front will eventually stall along the Southeast coast over the
weekend as high pressure builds across the Central Plains. High
pressure will build east with time through Tuesday, before another
cold front approaches the area Tuesday night into Wednesday. High
pressure will then return on Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Forecast on track this morning with some low stratus hanging
around. Only minor tweaks made. Previous full discussion
follows...

In the wake of a backdoor cold front, high pressure will remain
centered near Nova Scotia and the Gulf of Maine with ridging
extending southward across the Mid-Atlantic for Friday. However,
an area of low pressure cutting across the Great Lakes will send
a cold front across the Appalachians tonight, as that high
pressure and ridging quickly gives way. A steep inversion with
low clouds trapped across our region along with chilly northeast
flow in the boundary layer will result in another generally
gloomy day, though as the ridge shifts east, winds will turn
more southeasterly, allowing for a little milder air to push in.
Additionally, while the day will start off chilly with
temperatures in the low to mid 40s for most spots, cloud bases
will be noticeably higher along with an absence of any drizzle,
compared to the damp conditions Thursday morning. The exception
will be right around the Pocono Plateau and some of the adjacent
ridgetops into NW NJ early this morning. Highs will reach
farther into the 50s, with even some low 60s possible from
around Philadelphia southward into the Delmarva.

This afternoon as a weak pre-frontal shortwave trough and some
isentropic lift combine, scattered light showers will begin to
spread eastward across Pennsylvania, with isolated showers
possibly reaching the I-95 corridor toward sunset. Scattered
showers will then spread eastward across the coastal plain
toward midnight, then gradually taper off from west to east,
with just some lingering activity along the coast after sunrise
on Saturday morning. Rainfall amounts will only be around a
tenth of an inch. Some patchy fog may develop at times
overnight, but dense fog is not expected.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
The cold front will be located offshore by Saturday morning leaving
behind a few showers in its wake, mainly along the coast. All
showers will come to an end by late morning giving way to a mix of
sun and clouds during the afternoon as high pressure builds over the
High Plains. Despite the frontal passage, the front lacks any push
of "cold" air, so while drier air follows in its wake, temps on
Saturday will be relatively mild and seasonable. Model soundings
continue to suggest that our boundary layer will be well-mixed with
downsloping WNW surface flow, thus used the 850mb technique to get
our high temps on Saturday. Mostly mid to upper 60s with a few spots
(especially away from the coast) that may approach 70 degrees. Clear
skies are expected for Saturday night with light winds. Will have to
monitor the potential for some frost development across N NJ and the
Lehigh Valley in which the growing season becomes active.

For Sunday, the forecast remains tranquil and dry. High pressure
over the Central CONUS will broaden as it extends its ridge axis
east. Will have to keep eyes on a stalled boundary along the
Southeast Coast on Sunday where an area of low pressure develops
along it before moving into the western Atlantic. However, any
shower activity is expected to remain south of the Delmarva.
Otherwise, just an increase in clouds is expected on Sunday into
Sunday night with temperatures running a few degrees below
normal.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
High pressure located over the center of the country over the
weekend will shift east on Monday before moving south of the area
and offshore on Tuesday. At the same time, an area of low pressure
will track through the Great Lakes on Tuesday lifting into southern
Canada Tuesday night. A trailing cold front associated with the low
will bring a chance for some rain showers during the Tuesday night
into Wednesday timeframe. Have continued to carry an areawide chance
of PoPs (30-50%), with a targeted area of likely PoPs (up to 60%)
across the Poconos and north Jersey. After the frontal passage on
Wednesday, another area of high pressure builds over the Midwest
allowing dry conditions to return for Thursday.

Temperatures during the long term period will be near-normal through
Wednesday. Thereafter, temps look to lean below-normal as upper
trough settles over the Northeast late in the week.

&&

.AVIATION /13Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Today...Ceilings generally MVFR with unrestricted VSBY. Quite a
bit of variability in ceilings though, ranging from 015-030 and
even some low VFR possible at times. Those ceilings may continue
to vary in that range much of today, so low confidence in the
TAFs there. Light NE winds veering to more of a southeasterly
direction around 5-10 kt by this afternoon. Some light showers
coming into ABE/RDG in the afternoon ahead of a weak cold front,
potentially lowering VSBY to MVFR in the evening.

Tonight...Ceilings lowering into the 008-015 range for the most
part, with scattered showers spreading in from west to east
across the I-95 terminals in the evening, reaching the coast by
midnight. Rain will be light, but some MVFR VSBY possible at
times in mist. Would not rule out some occasional IFR VSBY
overnight with BR or patchy fog, especially ACY. Light SE to S
winds. Moderate confidence.


Outlook...

Saturday...Lingering sub-VFR possible early with isolated showers,
especially near KMIV/KACY, otherwise VFR expected. W-NW winds.
Moderate confidence.

Saturday night through Tuesday...VFR expected. W-NW winds expected
through Monday night, becoming E-SE winds on Tuesday. No significant
weather expected. High confidence.

&&

.MARINE...
A Small Craft Advisory is in effect currently for all the ocean
zones due to elevated seas from stronger NE winds on Thursday
and Thursday night. SCA conditions are expected on the ocean
waters through late tonight as seas around 6-7 ft this morning
gradually lower toward 5 ft into tonight. Otherwise, winds are
gradually easing this morning, ENE 10-15 kt, tending SE 5-10 kt
tonight.


Outlook...

Saturday through Tuesday...Fair weather. No marine headlines
expected. Winds up to 20 kt possible on Saturday night. Seas of 2-4
feet through Tuesday.

&&

.TIDES/COASTAL FLOODING...
Spotty minor tidal flooding is being observed within some of
the back bay communities of Ocean County, NJ and Sussex County,
DE. Minor tidal flooding should cease with this high tide cycle
within Rehoboth Bay, however some minor tidal flooding remains
possible through tomorrow morning around high tide within
Barnegat Bay. Tidal flooding is not expected oceanside for any
communities.


&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ450>455.

&&

$$

SYNOPSIS...MPS
NEAR TERM...Dodd/Hoeflich
SHORT TERM...DeSilva
LONG TERM...DeSilva
AVIATION...Dodd/DeSilva
MARINE...Dodd/DeSilva
TIDES/COASTAL FLOODING...Hoeflich