Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 162038
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
338 PM EST Mon Jan 16 2017

.SYNOPSIS...
High pressure will drift off the coast tonight. Low pressure is
forecast to pass across the Great Lakes on Tuesday with a
secondary low developing near Long Island on Tuesday night. 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 on Monday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
An area of low pressure over the Great Lakes will track
northeastward overnight with a warm front to our southwest. Lift
along the warm front will be enough for some areas of light
precipitation to develop toward sunrise. Used a MOS/Superblend
blend which keeps pops fairly low south of Philadelphia and
increases them through the chance range further north overnight.

Temperatures look fairly tricky overnight. On the warm extreme we
have the ECMWF and the latest HRRR which warm everyone except the
Poconos above freezing fairly quickly. However, the RGEM and the
NAM Parallel are colder. Given how it is usually hard to get rid
of low level cold opted closer to the colder data at this point
with the note that the RGEM has had a recent cold bias (so not
that cold). We have issued a freezing rain advisory to cover any
light periods of freezing rain overnight and during the morning
commute on Tuesday where temperatures have a good shot at falling
below freezing. Mid level temperatures will be well above freezing
, no snow. Most of the region outside the Southern Poconos, Lehigh
Valley and Northwestern New Jersey should stay above freezing
overnight. Any ice accumulation would be minor but could still
cause a few slick spots.

Winds will be under 10 mph with cloudy skies moving by later this
evening for the entire region.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
The warm front will move through the region on Tuesday with the
main low area of low pressure moving into Southeast Canada.
Additional periods of rain will likely develop with the lift along
the front and moisture streaming northward ahead of the low. The
steadiest rain looks to be across northern portions of the area
where up to a quarter inch of rain could fall. Went several
degrees under where the MET/ MAV and ECMWF MOS have temperatures
tomorrow given the clouds, rainfall and stubborn low level cold
around. Temperatures may actually rise more toward in the evening
than the high temperature forecasted through 00z.

Winds will still be under 10 mph with cloudy skies.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Three precipitation systems are expected to affect eastern
Pennsylvania, northeastern Maryland, Delaware and New Jersey
during the period from Tuesday night through Monday. However,
temperatures should remain above normal and the precipitation is
expected to fall in the form of rain.

The closed mid level low that was located over Kansas this
afternoon will progress to the northeast. The low is forecast to
become an open wave before passing over the northeastern states
around Tuesday evening. A 40+ knot low level southwesterly jet is
anticipated to be located over the coastal plain at that time and
it should be pushed out to sea on Tuesday night.

A mid level short wave trough that was located over Manitoba,
North Dakota and vicinity is forecast to progress to the southeast
and it should pass off the Middle Atlantic coast on Wednesday
afternoon.

At the surface, a warm front should be up into the upper Delmarva
and southern New Jersey on Tuesday evening with a cold front
moving through western Pennsylvania and West Virginia. Low
pressure is expected to develop around Long Island on Tuesday
night before racing out to sea.

We are anticipating a fair amount of lingering low level moisture
on Tuesday night and Wednesday even as the mid levels dry in the
wake of Tuesday evening`s short wave. We will continue to mention
rain and rain showers during that period along with areas of fog
for Tuesday night into Wednesday morning. The expected temperature
profiles continue to suggest all liquid precipitation.

Mid level ridging is expected over the eastern states for
Wednesday night through Thursday night. Another short wave trough
is forecast to lift over the northeastern states around Friday
night with the ridge anticipated to re-establish itself over the
east for the weekend.

Surface high pressure is forecast to build across our region from
west to east during the period from Wednesday night into Thursday
night. The high will likely bring dry weather conditions.

Surface low pressure is expected to move up the Ohio River Valley
and into the eastern Great Lakes on Friday before weakening. A
secondary low is forecast to develop off the Middle Atlantic coast
on Friday night before moving quickly out to sea. As the main
energy shifts from the Great Lakes to the coast, we are
anticipating another rain event for our region beginning around
midday on Friday and continuing through Friday night. Some rain
may linger into Saturday, especially in the northern part of our
region.

Surface high pressure is forecast to build into our area from the
north during the weekend.

A broad closed low should be located over the Ozarks and vicinity
late on Sunday and it is forecast to move toward the Ohio River
Valley on Monday. Rain associated with the system may begin to
overrun the surface high and it could spread into parts of our
region as early as Sunday afternoon. Rain is anticipated for both
Sunday night and Monday.

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Mainly VFR, with winds under 10 knots through this evening. A
broken deck with intermittent MVFR ceilings from KRDG to KPNE and
KACY southward into the evening will move from west to east near
and likely over some of these TAF sites. Ceilings thickening and
lowering at all TAF sites overnight to MVFR.

On Tuesday, rain showers will start moving into the area between
10- 13 Z. Steadier rain after 16z. Likely cold enough for a
potential brief interval of freezing rain around sunrise at KABE
and KRDG. IFR ceilings and visibilities likely, potentially going
lower in the afternoon. Winds still under 10 knots.

OUTLOOK...
Tuesday night and Wednesday morning...IFR and MVFR conditions are
expected with fog and rain.

Wednesday afternoon...Conditions are expected to improve to VFR.

Wednesday night through Friday morning...Mainly VFR.

Friday afternoon...Mainly VFR with a chance of rain.

Friday night...MVFR and IFR conditions in rain and fog.

Saturday...MVFR and IFR conditions in morning fog and rain,
improving to VFR for the afternoon.

&&

.MARINE...
Wave heights will still be around a foot or so with winds under
10 knots, fairly quiet on the waters.

OUTLOOK...
Tuesday night through Saturday...No marine headlines are
anticipated.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Freezing Rain Advisory from 4 AM to 10 AM EST Tuesday for
     PAZ054-055-062.
     Freezing Rain Advisory from 1 AM to 10 AM EST Tuesday for
     PAZ060-061.
NJ...Freezing Rain Advisory from 4 AM to 10 AM EST Tuesday for
     NJZ001-007-008.
DE...None.
MD...None.
MARINE...None.

&&

$$

Synopsis...Iovino
Near Term...Gaines
Short Term...Gaines
Long Term...Iovino
Aviation...Gaines/Iovino
Marine...Gaines/Iovino


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