Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS61 KPHI 210929
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
429 AM EST Wed Feb 21 2018

.SYNOPSIS...
Unseasonable Bermuda High pressure off the East Coast will
provide one more day of record-breaking warmth over the mid-
Atlantic region. A cold front will push south across the area
tonight and then stall to our south. Several waves of low
pressure will move northeast along this roughly stationary
frontal zone, resulting in periods of rain from Thursday through
Sunday. Another cold front will cross the area late on Sunday
followed by high pressure building in for the first part of next
week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Our area remains under the influence of a warm/moist southwest
flow as high pressure remains offshore of the east coast. This
warm and moist airmass has allowed for low clouds and fog to
develop again across the area, but not as widespread and dense
as Tuesday morning. The low clouds and fog will burn off and
lift by later this morning, similarly to yesterday. Another warm
day is in store today as we should mix through around 925 mb.
This will allow for temperatures to likely reach record levels
again for many areas today. We used a blend of mixed 925mb
temperatures and MAV/MET/ECMWF MOS for highs today.

A cold front will be approaching the area very late in the
afternoon, but will not make it into the area until after sunset. A
line of showers associated with this front will be moving toward the
area late in the afternoon, but again will likely not make their way
into our area until after sunset. But we will keep a chance of
showers in the forecast for late this afternoon in case they speed
up and make it in sooner.


&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
The cold front will make its way into and across our area this
evening and into the overnight hours. As it does so, a line of
showers will be making their way across our area as some
enhanced moisture and lift associated with the front move across
the area. The front will continue to sink south of the area
through the overnight, and the showers associated with the front
itself will slide southward as well. However, there will
continue to be a chance of rain later in the night as an
approaching short wave brings additional enhanced moisture and
lift to the area. One concern will be how cold the temperatures
for the northern areas across the Poconos and northwest New
Jersey can get. If they drop below freezing overnight, some
freezing rain may develop. Everywhere else, temperatures will be
well above freezing.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
A somewhat unsettled weather pattern will remain in place for
the first few days of the extended period, Thursday through
Saturday. Southwest flow aloft will carry moisture over the
area as several weak disturbances move quickly along the
residual frontal zone. It is difficult to say if any period will
be rain free, but a general rain looks more likely during the
days on Thursday and Friday and again Saturday night.

Colder air will continue to filter in behind the cold front on
Thursday, with high temps 25 to 30 deg colder than today. With
rain overspreading the area, temps may be cold enough for
freezing rain in far northwest NJ and adjacent PA Poconos,
especially late in the day and into the night. There is forecast
to be a persistent layer of above freezing air aloft so no snow
is expected. Surface flow is forecast to become more southerly
on Friday with rising temps and precip should become all rain by
about midday.

Saturday and Sunday should feature somewhat above normal temps
but continued periods of rain with a frontal boundary still in
the mid-Atlantic area. A pronounced upper trof and associated
deepening surface low are forecst to lift northeast from the
southern Rockies to the Great Lakes during this period. The
attendant cold front should move through our area Sunday
afternoon, preceded by widespread rain or showers.

For Monday and Tuesday, high pressure is then forecast to build
eastward from the Ohio Valley into the mid-Atlantic, resulting
in fair weather. The airmass behind Sunday`s front does not look
especially cold and temperatures look to be near or slightly
above normal.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
Today...IFR conditions will persist through the mid morning
hours, then the low clouds and fog will lift and burn off;
similarly to Tuesday morning. Once the low clouds and fog burn
off, VFR conditions will remain for the remainder of the day.
There is a small chance for showers late this afternoon, but
more likely this evening as a cold front moves across the area
tonight. Winds will be mostly south to southwest today, and
could gust 15-20 knots by the late morning into the afternoon
hours after the sun comes out and stronger mixing occurs.

Tonight...VFR conditions are expected this evening and overnight
across the area. There is a chance for showers this evening and
overnight as a cold front moves across the area. Winds will start
out southwest ahead of the front, then once the front moves through,
winds will switch to the north to northwest and could gust 15-20
knots.

OUTLOOK...

Thursday...Sub-VFR conditions possible in rain. NE winds 10-15
kt. Confidence: Average.

Thursday night...Sub-VFR conditions possible in scattered
showers. Mixed frozen precip in rain and sleet possible at
KRDG and KABE late. Confidence: Below average.

Friday through Sunday...Sub-VFR conditions in periods of rain.
Confidence: Average.

&&

.MARINE...
Conditions are expected to remain below advisory levels through
today and tonight. Winds will remain southwest today into this
evening with high pressure located to the east. Winds will
switch to the north to northwest. Winds will likely gust around
20 knots at times today and tonight and seas remain 3-4 feet.

The Dense Fog Advisory for the waters will remain in place trough
the morning hours, before the fog begins to burn off for the
remainder of the day.

OUTLOOK...

Wednesday night...Sub-SCA conditions expected. SW winds turning NW
overnight.

Thursday through Friday...SCA conditions possible on the ocean
waters.

Saturday...Sub-SCA conditions anticipated.

Sunday...SCA conditions possible.

&&

.CLIMATE...
More high temperature records are likely today. Here are the
records for Wednesday, February 21:

Atlantic City...74 in 1930
Philadelphia....72 in 1930
Wilmington......70 in 1953
Allentown.......67 in 1953
Trenton.........70 in 1930
Georgetown......71 in 2014
Mount Pocono....60 in 1930
Reading.........71 in 1930

The following are the record warm minimum temperatures for
Wednesday, all which should be exceeded.

ABE 46-1981
ACY 49-1954
PHL 49-2002
ILG 47-2002
RDG 48-1930
TTN 48-2002

The all time February max temps may be approached on Wednesday
at ILG, TTN, GED RDG MPO. All the all time monthly max`s are
listed below:

ACY 77 2/25/30
PHL 79 2/25/30
ILG 78 2/24/85
ABE 77 2/24/17
TTN 76 2/25/30
GED 77 2/25/17
RDG 77 2/24/17
MPO 70 2/25/30

Our expectation is that ACY will exceed the previous all time
record rainfall for February, by the end of the weekend. The
record is 6.50 inches in 2010. #2 is 1958 with 5.98 inches.

And...adding only half an inch to PHL and ILG will put both
locations in the top 9 ranking for Feb rainfall.

Have rechecked the monthly projection at PHL and the avg temp
continues at 41.0 or 5.3F above avg which is 8th warmest on
record, if it holds. Add or subtract a degree to the
average/departure and the ranking changes from 3rd to 11th. The
forecast 5.3F departure is ~2f warmer than the current
departure. I`d expect similar for the rest of our area...a bit
less in the north which will have better chances for colder air,
and a bit more warming in the south where the positive
departure as of yesterday was already 5F above normal, heading
for 7+. So all in all it appears we`re heading for a top 10
warmest February. Last year was the warmest on record, a
whopping 3+F degrees warmer than our current projection.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Dense Fog Advisory until 10 AM EST this morning for ANZ430-431-
     450>455.

&&

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.