Area Forecast Discussion
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FXUS61 KPBZ 231732

Area Forecast Discussion
National Weather Service Pittsburgh PA
1232 PM EST Mon Jan 23 2017

Low pressure will bring rain to much of the area into tonight,
with mixed precipitation at times along and north of I-80, and in
the higher ridge elevations. The next cold front arrives


Early afternoon update for precip types and a bit more afternoon
accumulation in the highest elevations of the southeast ridges. No
other significant changes.

Main band of rain from KDUJ southwest to near KZZV and slowly
shifting northwest, as closed low shifts to the Carolinas and a
coastal low develops. Colder air is working into the system from
the north and east, and do expect sleet and wet snow to mix in
along and north of I-80 later this afternoon, with a sleet to
snow mix developing in the Laurel Ridges, as well as higher
elevations of northern WV and Garrett county MD. Biggest change to
forecast is lowering of QPF through tonight, especially the
southeast ridges, as models are not seeing amount of mid level
drying that has already become entrained into the system. Snow
amounts in the higher elevations this afternoon and tonight have
been adjusted with more of a mix expected.

Late tonight as coastal low heads offshore of New Jersey, precip
will diminish with rain and snow showers into the higher
elevations, with light accumulations expected. Not much in the
way of cold air behind departing low, with Tuesday max temps near
10 degrees above the seasonal average.


The vertically-stacked low pressure system will advance up the East
Coast Tuesday, loosening it`s grip on the Mid-Atlantic and Upper
Ohio Valley. As a result, deep moisture will erode eastward, leading
to a general decrease in shower activity through midday Tuesday. Any
lingering showers that do remain will be light, transitioning from
snow or a rain/snow back to all liquid as temperatures rise.

We`ll see a brief lull in precipitation Tuesday afternoon through at
least early Wednesday with a transient high pressure. The next low
will move through the western Great Lakes Wednesday evening, draping
a relatively dry cold front through the region. Will keep only
chance PoPs along the front as the low nears. The better chance of
precipitation areawide will come Wednesday night stretching into
Thursday with the passing upper trough axis, as cooler air pours
into our mid-levels. Steepening lapse rates and injection of Great
Lake aggregate moisture will allow for rain showers to eventually
transition to at least a rain/snow mix. Temperatures will remain
well-above average in through the middle part of the week.


A conglomeration of upper lows will lead to broad troughing of the
upper-level flow through at least the weekend. This will bring the
return to more seasonal conditions. Several impulses passing through
the mean flow, will result in periodic snow chances. Some
accumulation potential exists through the weekend, especially north
and into the high elevations. While the Great Lakes are still
generally ice-free, surface temperatures of Lake Erie, in
particular, have dipped into the mid 30s. This will help limit any
lake enhancement as colder air arrives.


MVFR conditions should slowly deteriorate to IFR in rain through
the afternoon as low pressure tracks across N Carolina. A strong
pressure gradient on the N side of the low will also result in
gusty E winds through the afternoon before diminishing this
evening. Winds should gradually back to the NW tonight through
Tuesday. The precip could mix with and change to snow this
afternoon/evening especially for elevated ports and areas N of

The low should exit the E coast Tuesday with precip ending,
though MVFR ceilings are expected to persist with low level
moisture in place.

Periodic restrictions are expected late Wed through Sat with a
crossing cold front and subsequent upper troughing.




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