Area Forecast Discussion
Issued by NWS Mt. Holly, NJ-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KPHI 211350
Area Forecast Discussion
National Weather Service Mount Holly NJ
950 AM EDT Tue Mar 21 2017
Weak low pressure passes through the Mid-Atlantic this morning.
A cold front approaches tonight and passes through the region
by Wednesday morning. High pressure then builds in from the west
and moves offshore by the end of the week. As it does, a warm
front lifts north through the region on Friday. Low pressure
then approaches late in the upcoming weekend.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --A rather quiet weather day expected. The showers that crossed
parts of ern PA, NJ and Delmarva earlier have passed offshore
with no more expected today. Clouds prevail over the region this
morning but more breaks are expected across the NW later this
morning and over most areas during the afternoon. It will
probably become mostly sunny across nrn NJ and much of ern PA by
afternoon. Winds will be rather light since there are no strong
weather systems affecting the area today. We will continue with
the fcst temps of mid/upper 50s (South) and low 50s (North) for
the afternoon. We could be too low if the clouds depart the
-- End Changed Discussion --
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
A cold front will move across the area overnight tonight,
however no precipitation is expected as it is fairly moisture
starved. If there would be any precipitation it would across the
far south where the best chance for enhance low-mid level
moisture is forecast. Behind the front, cool air and gusty winds
will develop by daybreak. Winds behind the front could start
gusting 20-25 mph during the pre-dawn hours Wednesday.
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Cold front will be south of the Mid-Atlantic region by
Wednesday morning, and then strong CAA will be underway with
well below normal temperatures for the mid-week period. Low
pressure near the Canadian Maritimes will intensify, and
although there should not be many direct impacts from this low,
a tight NW pressure gradient will form between that and high
pressure building into the Great Lakes. This will tap into cold
Canadian air, resulting in highs in the 20s in the Poconos, 30s
for most of PA/NJ, and in the low 40s for MD/DE. With NW winds
15-20 MPH with gusts up to 30 MPH, wind chills will range from
the single digits up north to the 20s for most of the CWA.
Lows Wednesday night will be quite cold for this time of the
year, ranging from the single digits in the Poconos to the teens
for much of NJ/PA, and around 20 for the Delmarva.
Temperatures moderate a bit on Thursday as heights rise as the
low over the Canadian Maritimes moves offshore, and high
pressure over the Great Lakes builds east. Although still below
normal, highs will be in the 30s and 40s.
By Friday, high pressure moves off the Mid-Atlantic coast, and
return flow sets up as a warm front lifts towards the region.
Some overrunning precip will develop ahead of that warm front,
and a brief period of freezing rain is possible for the Lehigh
Valley/Pocono Mountains early Friday morning. Rain then develops
for most of the area by Friday afternoon as that warm front
continues to lift north through the region. Temperatures return
back closer to normal, topping off in the 40s and 50s.
On Saturday, high pressure off the Mid-Atlantic coast drifts
out to sea. Meanwhile, low pressure organizes over the Southern
Plains and Midwest. This will put the Northeast and Mid-Atlantic
in the warm sector, and temperatures will soar well into the
60s, and possibly the low 70s across MD/DE. Although some sites
may come close, high temperature records look to be safe.
Thereafter, low pressure over the Midwest tracks east through
the Ohio Valley and then towards the Appalachians Sunday and
Monday. Based on the latest forecast, there may be enough cold
air at the surface initially for a period of freezing rain
Sunday night/Monday morning. Otherwise, temperatures currently
look to be warm enough to support all rain, and can expect
precip for the start of the new week.
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
VFR conditions will continue across the TAF sites. Clouds will
prevail this morning in most areas. Breaks will become more
frequent N/W later this morning and then decreasing clouds most
areas through the afternoon. Winds will be rather light, mostly
from the W.
A cold front will cross the area overnight tonight. The front
is expected to be dry, with mainly mid-high level cloudiness.
Winds will become gusty behind the front with northwest gusts
20-25 knots possible.
Wednesday through Thursday night...VFR. NW winds 15-20 KT with
25-30 KT gusts on Wednesday.
Friday...Sub-VFR conditions in -RA. A brief period of -FZRA
possible at KRDG/KABE Friday morning.
Saturday...VFR initially. MVFR or lower late in the afternoon
and at night in -RA.
-- End Changed Discussion --
Conditions will remain below Small Craft Advisory levels
through today. However, winds will increase overnight behind a
cold frontal passage to Small Craft Advisory levels, then Gale
force by daybreak Wednesday.
Wednesday...Strong NW flow, with Gales on the NJ ocean waters
and SCA conditions on DE ocean waters and DE Bay. Brief period
of Gales possible on DE ocean waters late Wednesday morning.
Wednesday night...Conditions subside to sub-SCA criteria.
Friday...SCA conditions possible on the NJ ocean waters.
MARINE...Gale Warning from 6 AM to 11 PM EDT Wednesday for ANZ450>453.
Small Craft Advisory from 6 AM Wednesday to 6 AM EDT Thursday
Small Craft Advisory from 6 AM Wednesday to 2 AM EDT Thursday