Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 191722
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1222 PM EST Sun Feb 19 2017

.SYNOPSIS...
As a weakening system well to our south continues to shift
offshore, a cold front will move south across our region
later tonight. High pressure will build over the Mid Atlantic
during Monday into Tuesday before shifting offshore. A warm
front arrives early Wednesday, followed by another warm front on
Friday. As a surface low lifts across the Great Lakes region, a
cold front will sweep across our area on Saturday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
An upper-level low centered well to our south at midday
continues to move offshore. Another short wave is sliding across
northern New England this midday and a cold front is tied to
this feature. A surface trough has now shifted east of our
area. An area of mid level clouds continue to shift south and
east and will be clearing our coastal areas by mid afternoon.
Another area of high level clouds is moving southeastward and is
thinning some.

The low-level flow is northwest, which adds a downslope component
for the coastal plain. Another warm afternoon, although the far
north especially the higher elevations of the Poconos will be
cooler given weak cool air advection settling in. Some record
highs are expected this afternoon, and as of Noon Allentown and
Wilmington have tied their record high. High temperatures were
bumped up earlier for much of the region. Some cooling is noted
aloft, via the 12z Sterling, VA raob, however the boundary
layer remains warm. It will be warmer at the coast given enough
of an offshore flow.

The temperature and dew point grids were adjusted based on the
latest obs, then the LAMP/LAV guidance was used initially to assist.
The dew points were increased a bit, although these should drop
a bit through the afternoon especially across the northwest with
additional heating.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
Quiet weather is expected overnight as a northerly flow will develop
across the area as high pressure will be centered to our north
across Canada. A backdoor cold front will approach the area
overnight and toward daybreak, so clouds may begin to increase some
across the northern third of the area overnight.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
In the wake of the back door cold front, temperatures tomorrow
and Tuesday will be about 10 to 15 degrees lower than today.

By the later half of Tuesday, the surface high will be shifting
off shore as a pre frontal trough approaches from the west. This
will set up southerly low level return flow by Tuesday
afternoon. As a result, expect an increasing chance for rain
showers across the region.

The next warm front is expected by late Tuesday night/Wednesday
morning. Stayed close to a blend of guidance at this time, but
as confidence increases for an early morning warm front arrival
time, may need to go above guidance for Wednesday highs as
guidance continues to underestimate warm air advection events.

For Thursday and Friday additional warm air advection is
expected, with Thursday possibly being the warmest day of the
week (assuming that the previously mentioned warm front doesn`t
slide back south into our region as a cold front early
Thursday). However, warming on Friday could be tempered by
overcast conditions and an area of rain expanding into our
region thanks to a closed surface low lifting over the Great
Lakes Region.

The associated cold front with this low should sweep through the
region early Saturday, though there is some uncertainty with the
timing. As it does so, it should bring an abrupt end to the
rain. Even with the forecast strong cold air advection,
temperatures over the weekend may still be slightly above
normal.

&&

.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

This Afternoon...Areas of VFR ceilings, at or above 15000 feet,
will thin out from northwest to southeast. Northwesterly winds
around 10 knots. Some localized gusts to around 18 knots at
times.

Tonight...VFR overall. Some clouds around 2000 feet may develop
toward daybreak north and west of PHL. North-northwest winds
less than 10 knots.

Monday...Some clouds around 2000 feet possible early north and
west of PHL, otherwise VFR. North-northwest winds increase to
10-15 knots.

Outlook...
Monday night...VFR.

Tuesday...Ceilings could lower to MVFR with rain showers continuing
into Tuesday night.

Wednesday and Thursday...Mostly VFR conditions are expected.

&&

.MARINE...
Sub Small Craft Advisory conditions are expected across the waters
today and tonight. However, wind gusts may approach Small Craft
Advisory levels late tonight into Monday morning north of Little
Egg, so we will continue to monitor in case an advisory is
needed.

Outlook...
Monday...winds may gust near or above 20 kt at times, but
should stay just below 25 kt.

Tuesday through Thursday...winds and seas should stay below SCA
criteria.

&&

.CLIMATE...
Here are the record highs for today:

PHL 68-1948
ILG 67-1997
ABE 63-1997
TTN 68-1948
GED 74-1976
ACY 73-1961
RDG 67-1997
MPO 58-1981

&&

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

&&

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


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