Area Forecast Discussion
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FXUS61 KPHI 030117
Area Forecast Discussion
National Weather Service Mount Holly NJ
817 PM EST Fri Dec 2 2016
Low pressure continues to slowly move through the Canadian
Maritimes tonight through Saturday. Meanwhile, high pressure
builds into the Midwest, and then passes overhead Sunday before
moving offshore by Sunday night. A series of low pressure systems
will pass through the region next week, with a strong cold front
moving across the East Coast late in the week.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Cloud cover has expanded over most of our region. Snow showers associated
with enhanced low level instability and low level moisture
combination have propagated into the southern Poconos and far NW
NJ. The best moisture/instability combination should remain NW of
our region, so don`t expect precip to expand to the rest of our
region. However, for the Poconos and NW NJ, have kept mention of
slight chance of snow showers through the overnight hours as the
strong low level northwesterly flow will continue overnight. No
accumulation is expected as the dendritic growth layer is rather
dry and surface temperatures remain relatively warm.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
There could still be some isolated showers across the far north
at Saturday morning as a short wave/vorticity impulse passes by
the area, but any precipitation is expected to dissipate and move
out of the area by late morning. Northwest flow will continue
across the area on Saturday and will likely be a little gustier
than Friday. Wind gusts could reach 25 to 30 mph, with a few
higher peak gusts. Cloud cover is expected to be more expansive
Saturday than on Friday and will likely spread to cover the entire
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
An active pattern will be in place for most of the new week.
High pressure builds across the region this weekend, moving
offshore by Sunday night. On Monday, H5 trough/shortwave combo
will pass north of the region. Some rain is possible across the
region Sunday night across the southern two-thirds of the CWA,
while a rain/snow mix, changing to all snow, is possible for the
Lehigh Valley, Poconos, and northern NJ. Light accumulations may
be possible by Monday morning. Overall, QPF amounts will be light,
generally less than 1/10 inch.
Meanwhile, southern stream H5 trough/shortwave will move into
southern TX, and low pressure will develop over the Gulf Coast. As
a deepening upper low digs into the West Coast, it will carve out
a ridge over the eastern half of the U.S. The southern stream low
over the Gulf Coast will lift northeast into the TN/OH Valley
Monday night and Tuesday. Secondary low develops out ahead of it,
and then both systems slowly work their way east, moving offshore
Wednesday night. A rain/snow mix is possible at the onset Monday
night, with snow developing across northern zones. By Tuesday
morning, warm front associated with this system lifts north
through the region, allowing temps to warm up and changing precip
to all rain. PWATs will also increase to around 1", which is +2SD
above normal for this time of the year. Rain may be heavy at
As this is ongoing, deep low pressure over the West Coast will
deepen and broaden as it tracks east towards the Great Lakes.
Strong cold front presses east, and an airmass with 850 MB temps
of -20C to -25C will spread into the northern third of the nation.
This front will works its way through the region sometime Thursday
through Friday. Latest GFS has the front through by Thursday
night, and temps fall off from highs in the 40s/50s Thursday to
highs in the 30s/40s on Friday. A shot of rain and/or snow is
possible with its passage. Several upper level disturbances
passing through the region may keep some light precip in the
forecast through Friday.
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
VFR conditions will continue through the TAF period for all
sites even though ceilings around 4,000-6,000 feet will continue
for most, if not all, of the TAF period. Ceilings may lower
between 09 and 15Z, but at this point, still expect them to remain
above 3000 ft AGL for the TAF sites.
Winds will continue to be gusty through 06Z. The gusts will
likely drop off for a period overnight into Saturday morning, but
the gusts will increase again by mid-morning Saturday and gusts
25-30 knots during the day.
Saturday night and Sunday...VFR. NW winds 5-10 KT.
Sunday night and Monday...Sub-VFR possible, mainly Sunday night
and Monday morning. Light snow possible at KABE/KRDG, with light
rain possible elsewhere. Conditions improve Monday afternoon. W-NW
Monday night through Wednesday...Periods of MVFR/IFR conditions.
Generally rain, but some snow is possible at onset Monday night,
and then again Tuesday morning for KABE/KRDG.
We`ve upgraded the Gale Watch to a Gale Warning for the late
night through Saturday period. Small Craft Advisory level winds
will continue this evening before winds increase Saturday morning
and continue through the day. The Upper Delaware Bay continues
with a Small Craft Advisory for now.
Saturday night...SCA may be needed Saturday night for 25 KT wind
gusts on the ocean waters once gales end.
Sunday through Monday night. Generally tranquil conditions.
Tuesday through Wednesday...Low pressure passes across the
waters. Seas built to 5-7 feet on the ocean. Wind gusts to 25 KT
MARINE...Gale Warning from 4 AM to 6 PM EST Saturday for ANZ431-450>455.
Small Craft Advisory until 6 PM EST Saturday for ANZ430.