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Area forecast discussion 
National Weather Service Mount Holly New Jersey
405 PM EST sun Jan 25 2015

Synopsis...
low pressure located over the lower Ohio River valley this
afternoon will progress eastward and it will move off the middle
Atlantic coast on Monday. The low will intensify rapidly is it
moves northeastward, passing near Cape Cod late on Tuesday before
reaching Nova Scotia on Wednesday. High pressure from the west is
forecast for Wednesday. A weak low is expected to follow from the
west and it should pass over our region on either Thursday night
or Friday. Another area of high pressure is anticipated for next
weekend.

&&

Near term /until 6 am Monday morning/...
heading into this evening, a cold front will be situated just to
our south, with an area of surface low pressure along the western
extent of the boundary, progressing through the Ohio Valley. As
the surface low continues to track across the Ohio Valley and over
the Appalachians, the accompanying middle-level shortwave aloft is
shown to take on more of a negative tilt through the overnight to
early Monday. With these features in mind, we anticipate a light
snow to develop from west to east across the forecast area going
through late evening. Meanwhile, for the far southern Delmarva,
light rain or a rain/snow mix can be anticipated based on the
expected boundary layer temperatures during the overnight. Model
guidance continues to show fairly good convergence setting up into
the central part of the forecast area, and overall we expect a
general 1 to 3 inches of snow accumulation for central to northern
parts of the County Warning Area from the overnight to Monday afternoon. Any
possible mesoscale banding that develops will ultimately determine
where the somewhat higher values are realized, with some localized
amounts closer to four inches possible.

Mainly light northerly winds are expected later this evening,
becoming more northeast between 10 to 15 miles per hour during the overnight.
For nighttime minimum temperatures, we mostly took a met/mav
guidance blend with continuity, and we anticipate lows to range
from the teens across our northern zones to the middle 30s in the
far southern Delaware-Maryland-Virginia.

&&

Short term /6 am Monday morning through 6 PM Monday/...
through the daytime Monday, the previously mentioned low pressure
will track from around the central Appalachians early Monday
morning to off the North Carolina coast. Meanwhile, the previously
mentioned upper shortwave will deepen and become a closed upper
low. These features will then ultimately allow for quick
intensification of this system as it tracks northeast from late-
day Monday through Monday night.

A generally light snow will be ongoing through Monday morning as
the initial clipper low is passing by to our south on its way to
the coast, and as previously mentioned above, a general one to
three or four inch snow accumulation can be anticipated through
the middle of the day Monday, with the higher amounts expected to
extend from portions of eastern Pennsylvania into central and
northern New Jersey. Meanwhile, as temperatures begin to warm
through the daytime Monday, some mixing or change-over to rain in
expected for southeastern portions of New Jersey and down into the
Delmarva, generally limiting any Sunday night to Monday daytime
accumulations to around an inch or less.

Northeast winds through the daytime Monday will be increasing,
with gusts into the 25 to 30 miles per hour range, especially by the end of
the day. Maximum temperatures incorporated some met and mav
guidance with continuity, and we anticipate highs to range from
the lower and middle 20s north to the upper 30s and perhaps some
40s into the far southern Delaware-Maryland-Virginia.

&&

Long term /Monday night through Sunday/...
***a major snowstorm will affect our region for Monday night into
tuesday***

The storm for Monday night and Tuesday continues to come
together. The surface low will intensify rapidly off the middle
Atlantic coast on Monday night before moving up toward the waters
off eastern Long Island and southeastern New England for Tuesday.
The system should then continue northeastward reaching Nova Scotia
on Wednesday.

Abundant Atlantic moisture will wrap into the storm and we are
anticipating significant snowfall totals. From New Jersey
northeastward one to two foot totals are forecast to be common.
Amounts in excess of two feet are possible in our forecast are
toward northeastern New Jersey and the northern part of the New
Jersey coast, including Monmouth County and Ocean County.

The eastern edge of Pennsylvania may see amounts around a foot.
As one works westward toward the Susquehanna River valley, amounts
may begin to lessen toward the 4 to 6 inch range. The same is true
for the upper Delaware-Maryland-Virginia.

Based on high confidence, we have upgraded most of our New Jersey
counties, as well as much of southeastern Pennsylvania to a Winter
Storm Warning for Monday night and Tuesday. We have upgraded the
blizzard watch to a Blizzard Warning for the counties of
Middlesex, Monmouth and ocean.

For the western and southwestern parts of our forecast area, we
have left the Winter Storm Watch in place until we can get a
better handle on the expected impacts on the edge of the
precipitation shield. There may very well be a sharp cut off in
snowfall amounts as one approaches the Susquehanna River valley
and the Chesapeake Bay region.

Temperatures will be mostly in the 20 to 30 degree range during
the snow event with the brisk northeast wind backing toward the
northwest. Frequent gusts in excess of 35 miles per hour are anticipated in
our northern coastal counties and that is the reason for the three
counties being included in the Blizzard Warning.

The snow should end gradually from southwest to northeast in our
forecast area from Tuesday afternoon through early Tuesday night.

It should be dry and cold for Wednesday and Wednesday night.

A clipper system from the northwest and west may bring a shot of
light snow from late Thursday into Friday.

Another shot of cold dry air is anticipated for next weekend.

&&

Aviation /21z Sunday through Friday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.

This evening and tonight...VFR conditions will continue through
early this evening. By late evening, light snow should begin to
overspread from the west-east, generally in the 02z to 04z
timeframe. MVFR to IFR conditions will be developing at that time
and through the overnight. Some rain/snow mix is possible for the
southern taf sites, namely kilg/kmiv/kacy at the onset of
precipitation, but during the overnight, a changeover to all light
snow is expected. Some light accumulations, ranging mainly between
1 to 3 inches are possible for the Delaware valley sites and
westward to krdg/kabe, with generally less than an inch for
kmiv/kacy. Light north winds are expected to become more
northeasterly during the overnight, with speeds increasing to
between 10 to 15 knots.

Monday...generally IFR to possible low-end MVFR conditions are
anticipated to continue with light snow. Some rain/snow mix is
expected by late morning through the afternoon for kmiv/kacy.
Gusty northeast winds are anticipated, with gusts reaching between
25 to 30 knots, especially through the afternoon to evening.
Additional daytime accumulations to around an inch, with heavier
snow developing then into Monday night.

Outlook...
Monday night and Tuesday...significant snowfall will likely bring
air traffic to a standstill on Monday night and Tuesday.
Conditions are forecast to be LIFR and snow accumulations in
excess of one foot are anticipated at kphl with greater amounts to
the northeast and slightly lower amounts to the southwest.

Tuesday night...clearing is anticipated with a gusty northwest
wind.

Wednesday through Thursday morning...mainly VFR.

Thursday afternoon through Friday...a chance of snow. Conditions
may lower into the MVFR or IFR range for a time.

&&

Marine...
sub-advisory conditions are expected for the coastal waters and
Delaware Bay for most of tonight. Toward the early morning of
Monday, conditions will be ramping up to Small Craft Advisory levels as northeast
winds will be gusting up to around 30 knots by the 12z to 15z
Monday timeframe. For the rest of Monday then, continued
deteriorating conditions are expected through Monday afternoon,
with gale force wind gusts expected for Delaware Bay and the
coastal waters. By Monday night, storm force gusts are anticipated
for the coastal waters. Seas will be building to between 3 and 6
feet for Delaware Bay during Monday and into Monday night, with
seas eventually building to between 10 and 16 feet for the coastal
waters later Monday night. Marine headlines include a Gale Warning
for Delaware Bay and for the coastal waters from Cape May to
Fenwick Island, from Monday afternoon through the daytime Tuesday,
with storm warnings issued for the coastal waters from Sandy Hook
to Cape May, New Jersey through the daytime Tuesday.

Outlook...
Monday night and Tuesday...a marine Storm Warning is in effect
for our ocean waters off New Jersey. A Gale Warning is in effect
for the waters off Delaware and for Delaware Bay.

Tuesday night...gale force wind gusts are likely. Freezing spray
will be an issue, as well.

Wednesday...Small Craft Advisory conditions are expected with
additional freezing spray issues.

Wednesday night through Friday...no marine headlines are
anticipated.

&&

Tides/coastal flooding...
we have issued a coastal Flood Watch for Monday night's high tide
along the coasts of New Jersey and Delaware and on Delaware Bay.
With the strengthening storm off the middle Atlantic coast and the
strong northeast to north wind, moderate tidal flooding appears
likely.

We are thinking that there could be some minor tidal flooding on
the tidal Delaware River and perhaps on the upper Eastern Shore of
Chesapeake Bay. However, we have time to address that with an
advisory, if necessary.

Also, we will keep an eye on the daytime high tide on Tuesday. If
the wind is slow to back to the northwest, we may experience
another cycle with minor to moderate tidal flooding.

&&

Phi watches/warnings/advisories...
PA...Winter Storm Warning from noon Monday to 6 PM EST Tuesday for
paz070-071-103>106.
Winter Storm Watch from Monday afternoon through Tuesday
morning for paz054-055-060>062-101-102.
New Jersey...Winter Storm Warning from noon Monday to 6 PM EST Tuesday for
njz001-007>010-015>019-021>025-027.
Coastal Flood Watch from Monday evening through late Monday
night for njz012>014-016-020>027.
Blizzard Warning from noon Monday to 6 PM EST Tuesday for
njz012>014-020-026.
Delaware...coastal Flood Watch from Monday evening through late Monday
night for dez001>004.
Winter Storm Watch from Monday evening through Tuesday morning
for dez002>004.
Winter Storm Watch from Monday afternoon through Tuesday
morning for dez001.
Maryland...Winter Storm Watch from Monday evening through Tuesday morning
for mdz012-015-019-020.
Winter Storm Watch from Monday afternoon through Tuesday
morning for mdz008.
Marine...Storm Warning from noon Monday to 6 PM EST Tuesday for
anz450>453.
Gale Warning from noon Monday to 6 PM EST Tuesday for anz430-
431-454-455.

&&

$$

Synopsis...iovino
near term...Kline
short term...Kline
long term...iovino
aviation...iovino/Klein
marine...iovino/Heavener/Kline
tides/coastal flooding...iovino

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