Chester, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

040
FXUS61 KPHI 231501
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1001 AM EST Mon Dec 23 2024

.SYNOPSIS...
Arctic high pressure across New England will weaken and shift
offshore into tonight. A weak system will bring a round of light
wintry mixed precipitation to the region the morning of
Christmas Eve. Cool and dry high pressure will then settle to
our northeast, with mostly dry conditions and gradually
moderating temperatures. The high will retreat into the weekend,
yielding another possibility of precipitation.

&&

.NEAR TERM /THROUGH TUESDAY/...
Arctic high pressure centered over northern New York State this
morning will sag to the south and east towards New York City
and northern New Jersey later today, then moves offshore
tonight. A clipper system currently over the Midwest will track
east through the Great Lakes today before passing through
northern New York State tonight, then offshore on Tuesday
afternoon.

Sunny skies on tap for today, and after a bitterly cold
morning, temperatures remain well below normal today. With high
pressure departing, winds take on more of a southerly flow, but
the flow will be light, so there will not be much warm air
advection. Highs will top off in the mid and upper 20s north of
Philadelphia to the low to mid 30s across southern New Jersey
and Delmarva.

Clipper system will be over southern Ontario around midnight
tonight. Southerly flow continues ahead of this system, but
again, surface temperatures will be in the 20s through tonight,
not warming up to above freezing until later Tuesday morning. As
a result, initial precipitation will fall as snow. With the
center of the low over Central New York by daybreak Tuesday,
there will be nose of warmer air surging above 1000 mb for the
Delaware Valley and Delmarva. For these areas, there will be a
period of snow and freezing rain with a light glaze of ice
possible. 00Z HREF 24 hour probability of freezing rain greater
than 0.00 inches is generally 40 to 70 percent. As a result,
will go ahead and issue a Winter Weather Advisory for this mix
of snow and freezing rain for portions of the Delaware Valley,
including Philadelphia, for Tuesday morning. Snow is expected
for the southern Poconos, northern New Jersey, and the Lehigh
Valley, though snow accumulations should generally be less than
1 inch. Will not issue a Winter Weather Advisory for these areas
as snowfall amounts will be below criteria.

Although there may be some freezing rain across the eastern
shores of Maryland, Delaware, and southern New Jersey, right now
confidence is not high enough to warrant inclusion in the
Winter Weather Advisory at this time. Precip overall tapers off
fairly quickly around midday. Warmer, but still below normal on
Tuesday with highs in the upper 30s to low 40s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Following the potential light wintry precipitation on Christmas
Eve morning, Christmas Eve night and Christmas Day will feature
benign weather conditions.

The subtropical jet will be well to our south and polar jet
well to our north, leaving us with relatively weak zonal flow
locally. A weak shortwave will pass through Christmas night. At
the surface, high pressure will be located to our north to
northeast, with surface ridging extending southward into the
Mid Atlantic.

Overall, expect dry conditions and mostly sunny/clear skies
Christmas Eve night and Christmas Day. The weak wave will result
in some increasing cloud cover Christmas night. Most areas will
remain dry, but cannot completely rule out a stray flurry
Christmas night. Temperatures will rebound compared to the
frigid conditions over the weekend, but will remain about 5
degrees below normal across the board. Highs Christmas Day in
the 30s to low 40s and lows largely in the 20s to upper 10s.
Light north to northeast winds.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
The main story for the end of the week and into the weekend
will be the shifting synoptic pattern as weak ridging builds
across the eastern CONUS. The result will be moderating
temperatures to eventually above normal into the weekend, and a
lack of any significant weather. The details in the guidance
diverge into the weekend, but at this point it looks like there
could be a window of opportunity for some rainfall sometime over
the weekend. Some guidance is completely dry though. In any
case, so significant weather is expected at this point through
the holiday weekend.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of Today...VFR. Light N winds, nearly calm in most areas,
will become S around 5 kt after 18Z. High confidence.

Tonight...VFR through 06Z, then MVFR or IFR CIGs in light SN,
mainly for KRDG/KABE after 09Z. Light SN at KTTN, and light
SN/FZRA possible just before 12Z at KPNE/KPHL/KILG. S winds less
than 5 kt. Moderate confidence.

Tuesday...MVFR/IFR in SN at KRDG/KABE/KTTN, SN/FZRA at
KPNE/KPHL/KILG, and FZRA/RA at KMIV/KACY between 12Z and 18Z,
ending from west to east and improving to VFR after 18Z. W winds
around 5 kt. Moderate confidence.

Outlook...

Tuesday night through Friday...No significant weather or
restrictions expected. Light north to northeast winds.

&&

.MARINE...
Sub-Small Craft Advisory conditions rest of today through
Tuesday. N winds around 10 kt, becoming S this afternoon and
tonight. Winds turn W around 10 kt on Tuesday. Seas 2 to 3 feet.
VSBY restrictions in rain and/or snow Tuesday morning, ending
Tuesday afternoon.

Outlook...

Tuesday night through Friday...Conditions are expected to
remain below advisory criteria. North to northeast winds 10-15
kts and seas 2-3 feet. No significant weather.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory from 5 AM to 1 PM EST Tuesday for
     PAZ070-071-101-102.
NJ...Winter Weather Advisory from 5 AM to 1 PM EST Tuesday for
     NJZ016>018.
DE...Winter Weather Advisory from 5 AM to 1 PM EST Tuesday for
     DEZ001.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...Staarmann
NEAR TERM...MPS/RCM
SHORT TERM...Staarmann
LONG TERM...Staarmann
AVIATION...MPS/RCM/Staarmann
MARINE...MPS/RCM/Staarmann