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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 061404
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
904 AM EST Sat Mar 6 2021

.SYNOPSIS...
A final trough will cross the region on Sunday. Otherwise,
surface high pressure and tranquil weather will persist through
at least Wednesday. By Thursday, a cold front is expected to
approach the region. This front may remain over our near our
region through at least Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
This morning we are certainly making the best out of a thin
ribbon of moisture rounding the base of an upper level low
pressure system that is slowing pulling to the north and west.
This should mean that at least through the rest of the morning,
there will be some light snow showers or flurries with little
in the way of accumulation.

This the combination of a high pressure system extending
southward into the northern Plains and Great Lakes, and the
upper level low over Newfoundland responsible for a modest
pressure gradient across the Northeast, which is responsible for
our breezy conditions as of late. As a weak surface trough and
mid- level shortwave pivot eastward with the aforementioned low
to our northeast, high pressure will gradually build into the
region through the day and into Sunday with weak cold air
advection gradually backing off as well. The good news is that
this will relax the pressure gradient as the low begins to
gradually fill and pull off towards Greenland.

A broken mid-level stratus deck will continue to push through the
region as light snow showers gradually taper off to our north and
west closer to the lakes on the windward side of the Appalachian
crest. Can`t rule out a few flurries across the Poconos and into
Sussex County, NJ but no accumulations are expected. Partly cloudy
skies will persist through the day with more clearing as we head
into the overnight. A rather similar day to Friday, though the
weaker winds will result in less of a wind chill with highs in the
mid to upper 30s and wind chill values closer to the freezing mark.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The final of the mid level short wave troughs rotating around
the base of the main trough will quickly dig over the region
during the day on Sunday. Given the very dry air mass that will
still be in place, expect most areas to stay dry. However, given
the pattern, expect at least modest rising motion in the mid
levels. If the dry layer (which by model soundings look like it
will extend up through 700 mb) is shallower or not quite as dry
as expected, this trough could be enough for some very light
snow showers Sunday morning. At this point, I think the dry air
will win out, so have kept the forecast dry for now.

Once the mid level trough shifts southeast of our region, the mid
level ridge will begin to build east towards our region. Although
the more significant warm up won`t occur until we start seeing low
level southwesterly flow (beginning late Monday/Monday night), this
subtle shift, with the accompanying increasing thicknesses and mid
and upper level subsidence, will be enough for temperatures on
Monday to be 5 to 10 degrees higher than Sunday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Overview: Tranquil weather continues through at least Wednesday. A
cold front approaching the region Thursday and Friday could bring
the next chance for precipitation to the region.

Details:

Tuesday and Wednesday...both the surface high and mid level short
wave ridge shift over (and eventually east of) our region.
Consequently, we will see low level southwesterly flow, and
significant warm air advection. For both days, expect highs in the
50s and 60s. The good news is that the southwesterly flow should
also result in some moisture advection, which should help to limit
the fire weather threat somewhat (see fire weather discussion
below), but I agree with the previous forecaster that guidance can
have a wet and cold bias with this pattern especially during the
early transition season. Will be watching the trends over the next
several days.

Thursday and Friday...A cold front approaches the region. As
mentioned by the previous shift, the timing is still uncertain as
the front may slow or even stall for a period during this time.
However, it still looks like we won`t see the front progress through
the area until Friday. On Thursday though, the front may be close
enough that the front edge of precipitation in the warm sector (in
this case, all rain) will move into portions of our region, mostly
north and west of the fall line.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Today and tonight...VFR with scattered to broken mid-level clouds
through the day. Light snow showers with temporary MVFR
restrictions at KRDG and KABE, but these should be on the
downturn through the morning. West- northwest winds from 10 to
15 knots with gusts to 20 knots possible. High confidence.


Outlook...

Sunday...VFR. Northwest wind 5 to 10 kt. High confidence.

Monday... VFR. Winds gradually shifting from northwest to west-
southwest at 5 to 10 kt. High confidence.

Tuesday-Wednesday... VFR. Southwest wind 5 to 10 kt. High
confidence.

&&

.MARINE...
Cold northwest flow will continue through tonight with winds slowly
lessening through the day. Winds are expected to fall below advisory
criteria late this morning with the SCA lasting through 10 am.
Northwest winds from 15 to 20 knots into the afternoon and lasting
through the overnight.

Outlook...

Winds and seas should stay below SCA criteria Sunday through
Wednesday.

&&

.FIRE WEATHER...
After dew points in the single digits and northwest winds gusting to
35 mph at times yesterday, we are expecting slight improvement today
with west winds gusting from 20 to 25 mph, and minimum RH values
ranging from 35 to 40 percent. After collaboration with our state
fire partners yesterday, fuels are not expected to be wet enough
for a Special Weather Statement to be needed.

However, a prolonged dry and breezy period will be in place over the
region, so there will be close monitoring for the fire weather
threat into next week. At this point, it doesn`t appear that we
will reach low humidity criteria coincident with gusty winds,
but Monday should have very dry conditions, and Tuesday and
Wednesday will be much warmer than normal.

&&

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

&&

$$
Synopsis...Davis/Johnson
Near Term...Davis/Deal
Short Term...Johnson
Long Term...Johnson
Aviation...Davis/Johnson/O`Brien
Marine...Davis/Johnson
Fire Weather...WFO PHI