Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 291323
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
923 AM EDT Wed Mar 29 2017

.SYNOPSIS...
High pressure near Hudson`s Bay will build into our region
through Wednesday night. Low pressure moving through the Ohio
Valley on Friday will redevelop near the New Jersey coast
Friday night and move offshore on Saturday. High pressure
will move into the area for Sunday and Monday. Low pressure
over the Ohio Valley and its associated fronts will approach
our region on Tuesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Low pressure south and east of Montauk Point will continue to
drift out to sea today as high pressure over Hudson`s Bay builds
east. The pressure gradient tightens up a bit this morning, and
with slight CAA, can expect NW winds 15-20 MPH with gusts up to
25 MPH this morning. Winds abate by late morning/early
afternoon as gradient relaxes.

Clouds over eastern and southern NJ, and down into DE will
continue to scatter out, and mostly sunny skies will develop
across the whole CWA by late morning/early afternoon.

Max temps in the mid 40s in the Poconos, and in the low 50s
across northern NJ. Otherwise, highs in the upper 50s to low 60s
across central/southern NJ, SE PA, and in the low to mid 60s in
MD/DE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
Clear or mostly clear skies, a few fragments of sc in the early
eve and possibly a little cirrus. Some radiational cooling
expected. Light north wind. Normal or slightly below normal
mins.

Forecast basis: 50 50 blended 00z/29 GFS/NAM MOS guidance. Applied
minor 1-2F cooler than guidance adjustments in our 330 AM fcst
for tonight.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
The primary players during the long term will be two southern
stream systems that are expected to impact our region in the
Friday-Saturday and Tuesday time frames.

The first system may produce 1 to 1.5 inches of rain across
portions of the region, especially in the Delaware Valley. While
there could be some urban and poor drainage flooding, we do not
expect any major impacts on rivers and streams. There is also a
consistent signal in the models for mixed precip north of I-80,
with sleet and freezing rain the primary concerns, during the
Friday night and Saturday morning period. We have mentioned this
in the HWO.

Looking ahead to early next week, the next system is expected to
bring more precip to our region Monday night into Tuesday. This
setup looks warmer, given the absence of high latitude blocking,
and would favor predominantly rain.

&&

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

Today...MVFR CIGs across eastern/southern NJ, mainly at
KMIV/KACY, will become VFR by 14-15Z. Otherwise, VFR. SCT clouds
at 3500 ft possible this afternoon.

NW winds around 15 KT with 20-25 KT gusts this morning,
diminishing to 10-15 KT by late afternoon.

Tonight...VFR with fragments of sc in the evening and maybe some
thin cirrus at times. Light north wind.

OUTLOOK...

Predominantly VFR, except MVFR possible Friday into Saturday.

&&

.MARINE...
OCNL 25 KT gusts possible until 11 am or so on the ocean waters
this morning, but 25 KT gusts should not be frequent enough or
widespread enough to warrant a SCA.

SCA may be needed for ANZ450-51 (NNJ tonight).
Elsewhere...gusty north wind through the night to around 20-22
kt.

OUTLOOK...

SCA likely Friday into Saturday, with the potential for gale
force southeasterly wind gusts Friday night, mainly across the
northern NJ waters. Otherwise, sub-SCA.

&&

.TIDES/COASTAL FLOODING...
Though astronomical tides will be gradually diminishing through
the week now that we are past the new moon, the threat of minor
tidal flooding along the NJ and DE Atlantic coasts increases
late in the week. This is a result of a low pressure system
bringing a prolonged period of onshore flow. The tide of most
concern at this point is the high tide on Friday evening/late
Friday night. By this tide cycle, it will take a surge of 0.8 to
1.0 feet to reach minor flooding thresholds, which is possible
but still uncertain (it will be dependent on how quickly the on
shore flow develops and how strong it will be by then). At least
one source of guidance shows water levels reaching minor tidal
flooding thresholds with the Thursday evening/night high tide,
but that seems unlikely as the latest forecast depicts onshore
flow either developing right around or just after the time of
that high tide.

We have mentioned the potential of minor flooding along the
northern NJ coast in the HWO, where the threat is greatest
during the Friday evening/late Friday night high tide cycle.

&&

.CLIMATE...
Mo avg temps

    March Dep     Feb   DEP
ABE 38.0 -1.1     39.2 +8.5

ACY 41.6 -0.6     43.0 +7.7

ILG 41.7 -1.3     43.1 +8.0

PHL 42.2 -1.3     44.2 +8.5


This March will be a below normal month for temps.... One of
the VERY few the last two years.

We appreciate that this is possibly old news, but March temperatures
will average colder than the FEB average at all 4 long term climate
locations. The last time this occurred, 1984.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$
Synopsis...Franck
Near Term...MPS
Short Term...Drag
Long Term...Franck
Aviation...Drag/Franck/MPS
Marine...Drag/Franck
Tides/Coastal Flooding...
Climate...


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