Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 240036

Area Forecast Discussion
National Weather Service Mount Holly NJ
836 PM EDT Fri Mar 23 2018

High pressure briefly affects the area Saturday while an area
of low pressure passes to our south Saturday night. High
pressure will then build across the northeast later Sunday, then
across much of the east coast through early next week. A warm
front will likely lift north of the area Wednesday. Then a weak
cold front may move across the area later Wednesday or early
Thursday, before a storm system moves toward the east coast late
Thursday into Friday.


630 and 9 PM: Very little change expected.

Mid afternoon water vapor satellite imagery shows a mid-level
shortwave trough digging southeastward across central PA. There
is a weak surface reflection of this disturbance marked by a
subtle wind shift (from W-NW to NW) along a surface trough that
was moving southward through our region.

Mainly virga spreading se through our area given the very dry
sub- cloud layer (large T-Td depressions of 15-25 degrees) that
is backed up by a lack of obs reporting precip. Kept a mention
of isolated showers and sprinkles (snow showers and flurries
over the higher terrain).

Clouds should diminish from west to east tonight as drier air
works in. The pressure gradient remains tight enough to inhibit
winds at most locations from decoupling tonight, except at the
typical sheltered valleys in eastern PA and northern NJ as well
as the NJ Pine Barrens. Consequentially, forecast low
temperatures are approximately 3-6 degrees lower in these
favored radiational cooling spots (mid 20s) vs the urban/coastal
locales (near 30).


Saturday`s weather will be similar to today with no significant
changes in the large-scale pattern over the next 24 hours. The
region will be embedded in northwest flow around the backside of
the low pressure to our north/west. A rather diffuse surface
trough/cold front looks to progress southward through eastern PA
and much of New Jersey during the afternoon.

Following the passage of the mid-level shortwave trough this
afternoon, the next one digs southward toward the area about 30
hours later. Clouds will start to filter in from the north late
in the day, but with the deeper lift/moisture ahead of this next
system not arriving until Saturday night, expect mostly sunny
skies during the day, except perhaps transitioning to a partly
sunny deck in the late afternoon across northeastern PA and
northern NJ.

Given the similarities in thermal profiles and mixing potential
in the boundary layer tomorrow compared to today, a blend of
the bias- corrected MAV/MET guidance was used for to populate
temps for Saturday. Highs ranging from the mid 30s in the
southern Poconos to the upper 40s along and south/east of the
I-95 urban corridor equate to 5-10 degrees below climo.


Fairly quiet weather for much of the long term period, before
unsettled weather returns for the end of next week.

An area of low pressure will will pass far enough to our south
Saturday night that our area avoids another major snow event.
However, several short wave/vorticity impulse are forecast to
move across the area Saturday night through Sunday, while some
enhanced low-mid level moisture and low-mid level lapse rates
increase during the day as well. This could lead to some
isolated snow showers overnight Saturday into Sunday, although
it is a small chance at this time. Any showers during the day
may melt enough to fall as rain. Otherwise, a cool, breezy
period is expected Saturday night through Sunday.

The high pressure that builds across the northeast Sunday
builds down the east coast Monday through Tuesday. This will
keep dry conditions across the area Sunday night through
Tuesday. Temperatures remain below normal Monday and Tuesday,
but a warming trend begins by Tuesday.

The potential for unsettled weather returns for the middle to
end of next week. A warm front will likely lift north of the
area Wednesday. As this happens, some light precipitation may
fall across portions of the area, especially northeast
Pennsylvania and northwest New Jersey. If the precipitation fall
early enough, temperatures may be cold enough for a wintry mix
to occur, possibly a brief period of freezing rain. A weak cold
front may move across the area later Wednesday or early
Thursday, keeping a slight chance of showers in the forecast
into Thursday. However, this front may lift back northward into
the area as an area of low pressure moves up the Appalachians
and toward the area late Thursday into Friday. This storm system
could bring a round of gusty winds and rainfall to the area
late next week. Right now it looks like temperatures would be
warm enough for all rain.


The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Through Tonight...VFR sct-bkn near 6000 ft. An isolated shower
or sprinkle possible thru about 02Z but confidence/coverage too
low to mention in 18Z TAFs. A slight wind shift is expected
early this evening from about 290-310 degrees to 320-340 degrees
with the passage of a surface trough. A few gusts of 15-20 kt
this evening.

Saturday...VFR. Though CIGs may start out around 3 kft AGL in
the late morning/early afternoon, it should be FEW to SCT. CIGs
increase to 3.5-5 kft AGL after 18Z and could become BKN near
ABE-TTN in the late afternoon. NW winds around 10 kt.


Saturday night-Sunday...Generally VFR. Slight chance of
isolated snow showers which may temporarily lower conditions.
North to northeast winds gusting 15 to 20 knots. Moderate

Sunday night...Generally VFR. East winds gusting 15-20 knots.
High confidence.

Monday-Tuesday night...Generally VFR. High confidence.

Wednesday...Generally VFR. Slight chance of showers. Gusty
south winds 15-20 knots. Moderate confidence.


Through tonight...NW winds 5-15 kt gusting to 20 kt through the
remainder of the afternoon and tonight. However, issuing short
fuse-duration SCA for ANZ450-51 for gusts to 25 kt through 05z.
Seas 2-4 ft in coastal waters and 1-2 ft in the DE Bay.

Saturday...NW 5-15 kt. Seas 2-3 ft in coastal waters and 1-2 ft
in the DE Bay.


Saturday night...Conditions expected to be below advisory

Sunday-Sunday night...Small Craft Advisory conditions possible.

Monday-Wednesday...Winds expected to be below advisory levels,
but seas likely to remain well above advisory levels on the Atlantic
waters. Its early, so we`re not sure, but there is a chance that
a developing strong ocean storm in the western Atlantic could
send 8 to 10 foot 15 second period swells west into our coastal
waters Tuesday or Wednesday.


NJ NEW state record for March snowfall established per the NJ
State Climatologists office-Dr David Robinson

#1 Jefferson Township - Morris County  44.3" so far. 2018

#2 Rockaway Township  - Morris County  43.9" so far 2018

#3 Canistear Reservoir (Sussex County) 43.0 -1958 the previous
record til yesterday. Cooperative observer reports are no longer
taken at Canistear Reservoir for a direct comparison.

Below based on cooperative observer reports past century.

1913-1914 22.7

1957-1958 19.4

1955-1956 18.8

2017-2018 16.6 Ranked 4th snowiest March statewide

All regions below are top 10!

Northern NJ (Sussex,Passaic,Bergen,Warren,Morris,Essex,Hudson)

2017-2018 26.4 NEW record
1915-1916 25.6

Central NJ (Union,Middlesex,Hunterdon,Mercer,Monmouth,Somerset)

1955-1956 21.4
1913-1914 19.5
1966-1967 18.6
1957-1958 18.2
2017-2018 17.4

Southern NJ (Burlington,Atlc,Cumberland,Salem,Camden,Gloucester,Ocean
Cape May)

1913-1914 25.8
2017-2018 ranked #9 with 10.9"

The four climate sites in our Mount Holly Forecast area with
snowfall data are now in their top 5 snowiest March`s on record.

Snowiest March`s on Record...

Philadelphia - Currently tied for second.

1) 17.7" in 1941
2) 15.2" in 2018
2) 15.2" in 1914
4) 13.4" in 1958
5) 12.4" in 1993

Allentown - Currently at fourth.

1) 30.5" in 1958
2) 21.6" in 1993
3) 21.3" in 1960
4) 20.7" in 2018
5) 18.3" in 2017

Wilmington - Currently at second.

1) 20.3" in 1958
2) 14.2" in 2018
3) 13.9" in 1993
4) 13.4" in 1960
5) 13.3" in 1914

Atlantic City - Currently at fifth.

1) 17.6" in 1969
2) 15.6" in 2014
3) 13.4" in 1960
4) 12.7" in 1956
5)  9.6" in 2018

1-Day Snowfall Records in March...

Atlantic City, 5.7 inches on 3/21/18 is the 7th highest.

Wilmington, 6.7 inches on 3/21/18 is the 6th highest (2-day
total of 8.1 inches is tied for the 7th highest).

Allentown, 13.2 inches on 3/21/18 is the 4th highest behind
16.7 inches on 3/13/93, 16.5 inches on 3/20/58 and 13.8 inches
on 3/3/60.




Near Term...Drag/Klein 836
Short Term...Drag/Klein
Long Term...Robertson
Marine...Drag/Klein/Robertson 836
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