Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 241325
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
925 AM EDT Fri Mar 24 2017

.SYNOPSIS...
A warm front will lift to our northwest today, then a backdoor
cold front pushes through the area Saturday. This front is
forecast to stall near the southern portions of the area through
Sunday, then return northward as a warm front Sunday night into
Monday as low pressure moves through the Great Lakes. Another
low pressure if forecast to move out of the midwest and offshore
of the northeast Tuesday into Tuesday night, pulling a cold
front across the east coast. High pressure will try to build
down from the north Thursday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Broad area of precipitation in just starting to move into the
region. However, it is looking more scattered than it once was,
likely a result of dry air entrainment from the departing
continental polar air mass. Across our region, warm air and
moisture advection is already occuring. Almost all locations are
well above freezing and dewpoints have risen from the teens
just before sunrise this morning to the mid to upper 20s for
much of the region now. Thus, even taking into account
evaporative cooling effects, most of the region should be free
from any threat of freezing or frozen precipitation type. The
one exception is higher elevations of Carbon and Monroe Counties
which have temperatures generally 30-31 degrees F and dewpoints
in the upper teens and lower 20s. In these locations, it still
looks like a brief period of freezing rain is possible so will
keep the winter weather advisory going. However, if the warm air
advection trend/pace holds, the threat will likely be over by
late this morning so the advisory may be cancelled early.

Rain is still expected to taper off early this afternoon.
Temperatures are expected to be near normal. Highs this
afternoon will top off near 60 across MD/DE, and in the low to
mid 50s across southern NJ and SE PA. The Poconos and northern
NJ will top off in the mid to upper 40s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
Zonal flow sets up tonight as high pressure remains anchored
over the Southeast U.S. Conditions remain dry, but some mid-
level moisture will spread into the region, keeping cloudy skies
in place tonight.

Lows will drop into the low to mid 40s north of I-76, mid to
upper 40s across southern NJ and SE PA, and in the low 50s
across MD/DE.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
A backdoor cold front will sink through the area during the day
Saturday as high pressure moves across northern New England and
eastern Canada. The front is then expected to stall just to our
south through Sunday. As the front moves across the area, then
stalls to our south, several short wave/vorticity impulses will
slide across the area as well. This will lead to a chance of
showers across the area, though it will not rain the entire
time. Temperatures will be several degrees above normal Saturday
before the front moves through, then return closer to normal
Sunday on the northern side of the boundary. We will have to
keep an eye on the temperatures across the far north Saturday
night into Sunday. The NAM is hinting at the possibility for
temperatures to drop close to freezing, which could lead to a
period of freezing rain. For now, the forecast keeps all areas
above freezing.

The frontal boundary is then forecast to lift back northward as
a warm front overnight Sunday into Monday as an area of low
pressure moves through the Great Lakes region. Another couple
of short wave/vorticity impulses are forecast to move across the
area as the warm front lifts northward, and will enhance
precipitation potential across the area. Sunday night into early
Monday morning has the greatest chance of seeing more
widespread precipitation potential.

Another low pressure is then forecast to move out of the
midwest then offshore of the northeast Tuesday into Tuesday
night, pulling a cold front across the east coast. This will
keep unsettled weather across the area through Tuesday night as
several short waves/vorticity impulses slide across the area.
Behind the cold front, drier weather is then expected to return
for Wednesday into Thursday.

Temperatures are currently forecast to be a few degrees above
normal for the majority of next week.

&&

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

Warm front lifts north through the region this morning into
this afternoon. Quick shot of FZRA possible from 13Z-15Z at
KABE, otherwise, any rain that does fall will fall as plain
rain. Brief MVFR conditions likely, otherwise, VFR. Conditions
dry out after 18Z.

Light S winds this morning will become SW 8-12 KT this
afternoon, and then winds decrease to 5-10 KT tonight.

OUTLOOK...

Saturday-Tuesday...MVFR or IFR conditions with a chance of rain
possible through the period.

&&

.MARINE...
SW winds increase to 15-20 KT with gusts up to 25 KT across
northern NJ waters this afternoon and into this evening. SCA
remains in effect. Will hoist a SCA for DE Bay and DE ocean
waters as confidence in a period of 25 KT gusts for this
afternoon and early evening is increasing.

Conditions gradually subside to sub-SCA conditions tonight.

OUTLOOK...

Saturday-Saturday night...Conditions expected to fall below
advisory levels.

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

Monday-Tuesday...Winds may be below advisory levels, but seas
could remain elevated leading to Small Craft Advisory levels.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 1 PM EDT this afternoon for
     PAZ054-055.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for
     ANZ450>453.
     Small Craft Advisory from 2 PM this afternoon to 8 PM EDT this
     evening for ANZ454-455.
     Small Craft Advisory from 2 PM this afternoon to 6 PM EDT this
     evening for ANZ430-431.

&&

$$
Synopsis...Robertson
Near Term...Johnson/MPS
Short Term...MPS
Long Term...Robertson
Aviation...Robertson/MPS
Marine...Robertson/MPS



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