Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 031329
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
929 AM EDT Fri Apr 3 2020

.SYNOPSIS...
Low pressure south of the Canadian Maritimes will retrograde
back towards the Mainland today before departing over the
weekend. Meanwhile, high pressure over the Great Lakes and Ohio
Valley slowly builds east, and will be over the Northeast and
Mid-Atlantic over the weekend. This high moves offshore Sunday
night, and a warm front lifts north through the region. High
pressure returns on Monday, then moves offshore Tuesday. A
series of weak low pressure systems will pass through the region
next week until a stronger cold front passes through the region
late in the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The large offshore ocean storm will continue to retrograde
south- southwestward. As of 9 AM it was only about 90 miles off
the coast of Cape Cod. By late this afternoon, we are expecting
the low to be about 300 miles due east of the central Jersey
shore. This will lead to today being a considerably less
pleasant day than yesterday. Widespread cloudiness has already
pinwheeled southwest across most of the region and will remain
in place through the day. We also expect light rain showers to
pinwheel in as a trough on the back side of the low digs south
over our region. The best chance for showers will be in the
eastern half of the region, with activity gradually shifting
southward through the day. Showers look like they will be mainly
light and "spritzy", with the various high res models all a
little different in their evolution. Rainfall totals mostly less
than a tenth of an inch.

Another breezy day is expected, though it will probably not be
quite as windy as yesterday. While the center of the low will be
closer, it is also weakening and the gradients are starting to
slowly relax. Still, gusts to 30 mph are likely in many areas,
and a bit stronger at the coast. Highs are forecast to be mainly
in the mid 50s as 850mb temperatures near 0C and the widespread
clouds and showers will keep us a little cooler than average.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
Improving conditions are expected tonight as high pressure
starts to build in from the west. The offshore low will continue
shifting southward, but will begin to move in a more
southeasterly direction as it says goodbye to the East Coast for
good. Mostly cloudy conditions should linger through the night,
but the shower risk will decrease. In addition, as the low
moves away, the pressure gradient will weaken and winds will
finally relax in earnest. Lows ranging from the upper 30s to mid
40s as cloud cover and the lighter but still steady breeze will
help keep the lows a little above average.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Low pressure over the Western Atlantic, generally about 500
miles east of the Carolina coast, will continue to drift
offshore on Saturday. Meanwhile, high pressure over the Ohio
Valley builds east into western New York and Pennsylvania. Some
strong shortwave energy will pass through the region as well,
and although some sprinkles, perhaps a light rain shower, are
possible, think it should be dry enough at the surface that will
not include PoPs in the forecast. It will be cloudy, though,
with near normal temperatures in the mid to upper 50s. Onshore
flow will keep temperatures cooler along the coasts.

Low pressure continues to drift out to sea over the weekend,
and high pressure will be over the area on Sunday, and departs
late in the day. WAA begins, and temperatures warm back up into
the upper 50s and lower 60s. Another warm front lifts north
through the region Sunday night, and high pressure redevelops
west of the area for the start of the new week. It will turn
much warmer on Monday with highs in the mid to upper 60s
throughout.

From there, a series of low pressure systems will begin to
affect the area starting on Tuesday, and there will be at least
a chance for showers through Thursday. A stronger area of low
pressure passing through Canada should drag a stronger cold
front through the region late Thursday.

&&

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

Today...Mainly VFR conditions expected through this morning,
with ceilings gradually lowering. This afternoon, development of
MVFR ceilings is likely in most areas, though RDG and ABE may
remain VFR. Scattered light rain showers possible especially
east of PHL. Northwest winds around 15 kt with gusts up to 30 kt
possible, slowly diminishing late this afternoon and this
evening. Overall high confidence, though fluctuations between
low end VFR and high end MVFR conditions are possible.

Tonight...Mainly MVFR with ceilings around 2000-3000 ft, but
low end VFR may hold on near RDG and ABE. Winds becoming
northerly early, then north-northeasterly late, with speeds
decreasing to around 5 to 10 kt. High confidence.

Outlook...

Saturday...VFR. NE winds 5-10 kt, becoming LGT/VRB Saturday
night. High confidence.

Sunday...VFR during the day, then a chance for MVFR with
scattered showers Sunday night as a warm front lifts through the
region. W-SW winds 5-10 kt. Moderate confidence.

Monday through Tuesday...Mainly VFR conditions expected. Light
west to southwest winds, with localized sea breezes along the
coasts. Moderate confidence.

&&

.MARINE...
Today...A gale warning has been issued for the southern coastal
waters and the lower Delaware Bay as gale force gusts are
expected to continue at least through mid day near the mouth of
the Delaware Bay. SCA conditions are expected elsewhere.

Tonight...On Delaware Bay, conditions should subside to sub-SCA
levels early with winds gradually turning northerly and gusts
diminishing to 20 kt or less. On the Atlantic coastal waters,
SCA conditions will continue. Winds will shift to northerly then
north- northeasterly at 15 to 20 kt with gusts to 30 kt. Seas
building to 5 to 8 ft.

Outlook...

Saturday through Sunday night...A prolonged period of SCA
conditions expected for the ocean waters. There will be wind
gusts to 25 kt on Saturday, and then seas will remain elevated
at 4-6 feet through Sunday. Sub-SCA conditions expected on DE
Bay during this time.

Monday through Tuesday...Sub-SCA conditions expected on DE Bay
and the Atlantic Coastal waters.

&&

.TIDES/COASTAL FLOODING...
Low pressure over the western Atlantic Ocean will combine with
increasing astronomical tides due to an approaching full moon to
result in a period of coastal flooding during the times of high
tide late tonight through Saturday morning.

Widespread minor tidal flooding is possible, with areas of
moderate flooding across southern New Jersey and Delaware. Will
go ahead and hoist a Coastal Flood Watch for Atlantic, Cape May,
and Cumberland counties in southern New Jersey, and for Kent and
Sussex counties in Delaware from 2am-10am Saturday.

For the northern New Jersey areas of Monmouth, Ocean, and
southern Burlington counties, a Coastal Flood Advisory will
likely be needed for minor coastal flooding, likewise for New
Castle county, Delaware, and Salem county, New Jersey.

For the tidal Delaware River, at least one round of minor
flooding is possible on Saturday, but confidence is a little
lower owing to increased model variability and predominant
northerly flow. For the eastern shores of Chesapeake Bay,
confidence is also rather low. The north to northwest flow would
suggests a reduced threat, but will need to watch lower
portions of the bay closely to determine if sufficient water
evacuation occurs between high tides to mitigate the threat of
higher tidal levels in upper portions of the bay.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Watch from late tonight through Saturday morning
     for NJZ021>025.
DE...Coastal Flood Watch from late tonight through Saturday morning
     for DEZ002>004.
MD...None.
MARINE...Small Craft Advisory until 7 PM EDT Saturday for ANZ450>452.
     Gale Warning until 4 PM EDT this afternoon for ANZ431-453>455.
     Small Craft Advisory until 4 PM EDT this afternoon for ANZ430.

&&

$$
Synopsis...MPS
Near Term...Johnson/O`Brien
Short Term...O`Brien
Long Term...MPS
Aviation...MPS/O`Brien
Marine...Johnson/MPS/O`Brien
Tides/Coastal Flooding...



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