Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 230845
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
345 AM EST Thu Feb 23 2017

.SYNOPSIS...
A cold front moving through the Great Lakes today will stall just
north of our region tonight into Friday, before lifting northward as
a warm front Friday night. This will be followed by a strong cold
frontal passage on Saturday evening. High pressure will traverse the
middle Atlantic Sunday into Monday. A frontal boundary will setup
near our region during the early to middle part of next week, and
several waves of low pressure are expected move along it.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A light south to southwest surface flow continued to bring mild air
and increasing low level moisture into our region during the night.
Low clouds and fog have developed across parts of northeastern
Maryland, Delaware, southeastern Pennsylvania and southern New
Jersey. The low clouds and fog are expected to expand northward. We
have issued a Dense Fog Advisory for much of the central and
southern parts of our forecast area. It is in effect until 10:00 AM.

The low clouds and fog are expected to lift and break gradually from
mid morning until early afternoon. We are anticipating some
sunshine during the afternoon hours. Temperatures are forecast to
respond to the sunshine and the mild south to southwest flow. Highs
should reach the 60s in much of eastern Pennsylvania and northern
and central New Jersey. Maximum temperatures are expected to be near
70 in much of northeastern Maryland, Delaware and southern New
Jersey. The exception will be locations near the coast which should
not get above the 50s due to the chilly water temperatures.

It looks as though we will set a new record high temperature at
Georgetown, Delaware today based on the latest projection. Mount
Pocono, Pennsylvania may get close, as well. Our other six primary
climate sites (Philadelphia, Wilmington, Atlantic City, Trenton,
Allentown and Reading) will likely fall short of their record highs
for today.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
Our region should be more solidly in the warm air for tonight. As a
result, we may see more stratus than fog development except near the
water. Nevertheless, we will continue to mention at least some
patchy fog for late tonight.

Scattered showers may spread across parts of eastern Pennsylvania
and northern and central New Jersey. Rainfall amounts should be
light, generally a few hundredths of an inch.

The wind is forecast to be light for tonight and low temperatures
should range from the middle 40s in the Poconos and far northern New
Jersey to the lower 50s on the coastal plain.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Active pattern in the Friday thru Wednesday period. Dense fog is
possible Friday and Friday night. There is a marginal risk of
severe thunderstorms on Saturday. There is also the potential
for daily record high temperatures on Friday, especially
Delmarva. Temperatures cool to seasonal levels on Sunday.

A more zonal flow sets up in the Monday thru Wednesday time
frame with additional chances of light precip along with a
return to above average temperatures. There is a lot of
uncertainty regarding coverage and timing of precip in the early
to middle part of next week.

Friday will feature a warm front just north of the area, with
diffuse shortwave energy moving along it. This will promote the
chance for scattered rain showers, mainly north of an I-195 to
PA Turnpike line. Given the proximity of a warm front, which
may briefly backdoor to the south, we anticipate considerable
cloudiness across much of NJ and eastern PA. This is reflected
in our temperature grids, and will likely limit record high
potential across this area. Further south across Delmarva, we
have maintained warmer temperatures (mid-70s), and thus there
is a greater potential of setting records across this area.
With the nearby frontal boundary, we expect fog through mid-
morning Friday and again Friday night. The fog could be dense,
and we have continued a mention of this in the HWO.

Saturday and Sunday...A strong cold front moves through the
region Saturday evening. The synoptic pattern is favorable for
a squall/convective line to move through much of the area, and
SPC has placed our entire region within a marginal risk of
severe thunderstorms in their day 3 convective outlook. Thus,
we maintain a chance of thunder in the forecast. Some heavier
downpours are also likely, but amounts are expected to be less
than one inch. High temperatures on Saturday are expected to
fall just shy of daily records. Fair weather is expected for
Sunday, with a return to near normal temperatures, and gusty
west-northwest winds.

Looking ahead to Monday thru Wednesday, several shortwaves will
interact with a frontal boundary that sets up near our region,
offering additional chances of light precipitation. Details in
timing and coverage continues to be low, so the forecast shows a
general slight chance of showers during this period. Snow
showers are possible Monday and Tuesday nights. We expect
temperatures to return to above average levels, generally
around 5 to 10 degrees above normal.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Abundant low level moisture will continue to result in the
development of low clouds and fog in our region early this morning.
We are forecasting widespread IFR conditions. A gradual improvement
is anticipated from mid morning through early afternoon with most
locations rising into the VFR category by 1800Z or 1900Z.

VFR conditions are anticipated from mid afternoon into this evening.
However, a return of low clouds and fog is possible late tonight.
Also, there may be scattered light rain showers around KRDG and KABE
tonight.

A light and variable wind early this morning should settle into the
southwest and south around 5 to 10 knots for this afternoon. The
wind is anticipated to become light and variable again for
tonight.

OUTLOOK..

Friday through Saturday...There is the potential for MVFR/IFR
at times, especially Friday night, and again on Saturday with
showers and potential thunderstorms ahead of a cold front. Winds
out of the south on Saturday could gust up to around 20 knots.

Saturday night and Sunday...Becoming VFR Saturday night
with gusty west-northwest winds anticipated into Sunday, 25 to 30
knots at times.

&&

.MARINE...
A southwest to south flow will continue on the coastal waters of
Delaware and New Jersey for today and tonight. Sustained wind speeds
should remain less than 15 knots with no gusts in excess of 20
knots. Wave heights on our ocean waters should range from 2 to 4
feet. Waves on Delaware Bay will likely be 2 feet or less.

Mild air will continue to advect over the chilly water. Dew point
readings will increase further above the water temperatures
resulting in widespread fog. We have issued a Dense Fog Advisory
over the water until noon for the time being. We may need to extend
the advisory, especially on our waters north of Atlantic City.

OUTLOOK...

Sub-SCA conditions are forecast Friday. SCA possible Friday
night thru Monday, with period of gales possible on Sunday.
Sub-SCA conditions are forecast Tuesday.

&&

.CLIMATE...
For those who refer to the RTPPHI: it hasn`t run correctly on
its 715 AM/PM cron since the 20th but we were able to produce
a version around 8 PM tonight. Not all the trace amounts of rain
are in there. This will have to suffice until an improved fix
hopefully is implemented Thursday evening. Thank you.


For reference, here are the high temperature records for Thursday,
Friday and Saturday.

Location    Thursday 2/23   Friday 2/24   Saturday 2/25

ACY         72-1985         75-1985       77-1930

PHL         75-1874         74-1985       79-1930

ILG         72-1985         78-1985       78-1930

ABE         71-1985         76-1985       74-1930

TTN         74-1874         74-1985       76-1930

GED         67-1985/1990    72-1961       76-1975

RDG         72/1932/1922    77-1985       77-1930

MPO         60-1977         60-1984       70-1930

The following monthly and seasonal expectations were recalculated
with todays max/min and then the official 330 PM Mount Holly
forecast.

It is virtually certain that the numbers below will stand and
that our forecast area is experiencing a record warm, or at
least a 2nd warmest January on record and a top 10 warmest
winter.

Records date back to the late 19th century. Details below. These
values are probably on the lower side of the solutions.


February:

PHL 43.3. #1   Normal 35.7   Record 42.2-1925     POR 1874

ABE 37.6  #2   Normal 30.7   Record 38.6-1998     POR 1922
There is a pretty good chance ABE will end up warmer, very very
close to the record.

ACY 42.2  #1   Normal 35.3   Record 41.6-1890     POR 1874

ILG 42.3  #1 tie  Normal 35.1 Record 42.3-1903    POR 1895



Winter (DJF)

PHL 40.1 #7

ABE 35.4 #5

ACY 39.6 #10

ILG 39.1 #6 tie


Past two years of monthly average temperatures through February
2017, a summary of above normal months listed below:

For ABE: 23 consecutive months of above normal temps!

FOR PHL: 22 of the past 23 months have been above normal.

For ACY: 19 of the past 23 months have been above normal. For ILG:
17 of the past 23 months have been above normal.

(Jan Feb March 2015 was the last time we had significant and
persistent below normal monthly temps.)


Snow:

February least on record:

Atlantic City should/could end up tied for 5th.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Dense Fog Advisory until 10 AM EST this morning for PAZ070-071-
     101>106.
NJ...Dense Fog Advisory until 10 AM EST this morning for NJZ013>027.
DE...Dense Fog Advisory until 10 AM EST this morning for DEZ001-002.
MD...Dense Fog Advisory until 10 AM EST this morning for MDZ008-012-
     015-020.
MARINE...Dense Fog Advisory until noon EST today for ANZ430-431-450>455.

&&

$$
Synopsis...Franck
Near Term...Iovino
Short Term...Iovino
Long Term...Franck
Aviation...Franck/Iovino
Marine...Franck/Iovino
Climate...Drag



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