Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 170954
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
454 AM EST Tue Jan 17 2017

.SYNOPSIS...
Low pressure is forecast to pass across the Great Lakes on today
with a secondary low developing near Long Island on tonight.
The system is anticipated to move out to sea on Wednesday. High
pressure should follow for Wednesday night through Thursday night.
Low pressure is forecast to move across the Ohio River Valley and
the eastern Great Lakes on Friday with a secondary low developing
off the Middle Atlantic coast on Friday night. High pressure is
expected to build into our region from the north for the weekend.
A broad area of low pressure is anticipated to approach from the
southwest early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
450 AM: confidence on Freezing rain advisory is still less than
ideal except elevations where its 31-32F at 445 am.

Thinking that this is primarily an elevated ice event: bridges/overpasses/
trees and branches later this morning through tonight fm northern
Sussex County into northwest Monroe county. Yes there can be spotty
elsewhere this morning but i dont see widespread icing, at least
not at this 445 am writing due to lack of organized qpf while wet
bulbs near freezing.

Still no icing groups at any metar sites (I group) in our area
through 09z, which means, little if any icing, so far. We have
messaged FB for any reports. The 00z/17 GFS/NAM keep primary
measurable prior to 15z down on the Delmarva and s NJ. That
probably means little in the way of overnight icing and the
question thereafter, where to keep the advy on Tuesday. Wet bulbs
still say icing possible in portions of the forecast area but as
of this writing...am thinking only Monroe County Sussex County
high terrain will have any substantive icing once rain begins in
earnest between 15z-17z. Its a close call on all of this. Light
winds.

So, rain overspreads the entire area 15z-18z then may quit at
times Delmarva late day or evening. A cold rain. Light wind trending
northeast, north of I-78 as low pressure forms in central NJ late
in the day while winds are southeast over the Delmarva trending
south late in the day with max temps there late in the day.

Basically blended the 0z/17 EC 2m temps with the 00z/17 MAV MOS
temps. Met and MOS temps as well as 2m temps on the models are
substantially too cold early this morning and not used prior to
12z). Max temps several degrees above normal.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
Cold rain and drizzle north of I-78 while s of I-78... periods of
rain and drizzle diminish, especially Delmarva where there may be
9 hours of rainfree weather. Still a risk of glazing vcnty KMPO
and High Point NJ but no advy extension attm.

Fog may become a problem, especially late and especially south of
I-78.

00z/17 ECMWF 2 m temps blended with the colder of the avbl NCEP
MOS guidance.

Min temps around 15 degrees above normal.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The long term part of the forecast will feature a continuation of
mild temperatures for mid-late January. High temperatures will be
mostly around 10 degrees above norma thru the period.

There will be several wet weather systems. The first will be across
the area Wed morning, but pops will decrease thru the day as low
pressure and its fronts pass east of the region during the afternoon.
This will be followed by a period of dry weather from wed night thru
Fri morning.

Low pressure will move into the upper Great Lakes region Friday and
its attached warm front will approach/cross the region Fri into Sat.
A period of showers will accompany the feature. Overall rainfall
amts will be rather light however.

A stronger system will move slowly across the Mississippi/lower Ohio
Valley region Sun-Tue next week. This will draw moisture northward
from the Gulf of Mexico. It appears that a decent rainfall event
will occur across our forecast area Mon-Tue with this system.
Rainfall amts of 1 to 2 inches could occur across our area. Pops are
already in the low likely category for this time period. We will
leave it as is for now. Latest GFS/EC are showing good agreement with
the broad scale timing/location of the system.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Early this morning...Cigs 1500-6000 ft...mainly in the 1500-3000
ft range. light south wind. Vsby will decrease to mvfr in showery
rains toward 11z vcnty KILG.

Today...MVFR Cigs lower to IFR during midday with vsby decreasing
to MVFR in periods of rain. light wind...trending northeast or
north KABE/KRDG while light south to southeast elsewhere.

Tonight...Widespread IFR conditions expected with rain diminishing
to drizzle and eventually fog as cigs lower through the night.
Light wind trending north to west entire area overnight.

OUTLOOK...
Wed...Morning clouds/showers will yield to improving cigs/vsbys.
Wed night thru Fri morning...Mostly VFR expected.
Fri afternoon thru Saturday...Lower cigs/vsbys possible. Showers.
Sat afternoon-Sat night...mostly VFR.

&&

.MARINE...
No headlines through Tonight. Wave heights will still be around a
foot or 2 with winds under 10 knots, fairly quiet on the waters.

OUTLOOK...
Wed thru Sun...Sub-SCA conditions. Showers Wed morning, Fri-Sat
  morning.
Sun night...SCA developing with low end Gale possible. Showers.

&&

.CLIMATE...
January 2017 is projecting 17th warmest January on record with the
database back to 1874. The current monthly avg through the first
16 days of 35.8 degrees is forecast to warm by at least two
degrees,when all is said and done for January. This should mean a
similar warmup for the remainder of our forecast area so that the
generally 2 to 3 degree above normal temperatures will end up 4
to 5 degrees above normal. The exception...Mount Pocono, which was
normal for the first 16 days but it too should end up at least
two degrees above normal.

PHL, using todays Mount Holly fcst thru 7 days, then the FTPRHA
for D8-11, finally using normal temps the 28th-31st offers a
monthly avg of 38.1 degrees, or 5.1 above normal.

We probably wont post on this again for a few days but suffice to
say...the warmth during the heart of the coldest part of winter
eases the fuel oil bite on the bank account.

We have seen the BUFAFD climate section commenting on stratwarm.
While not an expert on the subject, I do like the NAEFS D8-14 as
generally helpful in outlooking temperatures with respect to
normal. As it stands this morning (00z/17), the NAEFS is still
with a near 90 percent probability that the 6 day period of the
January 25-February 1, as a whole, will be above normal. It might
end up only a smidge above normal but there is not clear cut sign
of a major cold outbreak here before the 28th of January with
colder than normal trends showing up toward Feb 1. Usually there
is a complication on arrival of these potential regime changes.

In the meantime,  enjoy the warmth.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Freezing Rain Advisory until 7 PM EST this evening for PAZ054-
     055.
     Freezing Rain Advisory until 10 AM EST this morning for
     PAZ060>062.
NJ...Freezing Rain Advisory until 7 PM EST this evening for NJZ001.
     Freezing Rain Advisory until 10 AM EST this morning for NJZ007.
DE...None.
MD...None.
MARINE...None.

&&

$$
Synopsis...Iovino/O`Hara
Near Term...Drag 454
Short Term...Drag
Long Term...O`Hara
Aviation...Drag/O`Hara
Marine...Drag/O`Hara
Climate...454


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