Area Forecast Discussion
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FXUS61 KPBZ 212158

Area Forecast Discussion
National Weather Service Pittsburgh PA
458 PM EST Sun Jan 21 2018

Warm temperatures will dominate through Monday. A cold front
brings more organized rainfall Monday night. Seasonable
temperatures and snow showers return by late Tuesday.


Warm advection continues over the CWA this evening, even as the
boundary layer has deepened enough to eradicate any fog or
drizzle. As we go into the overnight, really only a few
extremely patchy areas of light rain will translate through the
SE portions of the CWA with no support noted for really any
further rainfall across the CWA in the evening hours.

As we go into the overnight, a warm front will start to develop
generally along an E-W axis near or just north of Pittsburgh as
slowly migrate northward. Light rain chances will start to
increase to the north of this, however model guidance doesn`t
favor much in the QPF even if rainfall does materialize. Fries


The model consensus favors the warm front lifting well north of
the CWA on Monday. As this occurs, layer moisture departs with
it for the duration of the strongest insolation hours as we
clear out. With warm advection bringing 850 mb temperatures into
the +8 to +10C range, decent mixing below it, and ample
sunshine, most of the CWA should leap into the 60s. That said,
this sunny interlude will be short-lived, as the model consensus
favors a cold front crashing the party in the evening, bringing
a certainty of showers and falling temperatures. Fries

The stacked low still tracks across the Mississippi Valley and
into the Great Lakes by Tuesday morning. This drags a cold front
across the region on Monday night. Given the consistent model
handling, upped PoPs to near 100 percent. The relatively thin
precipitation shield and progressive nature of the front means
that QPF is still expected to top out around a half inch through
12Z Tuesday. Thus, outside of possible isolated issues due to
lingering river ice, flooding issues will be held to a minimum.

A more seasonable air mass will rush in behind the boundary on
Tuesday, with falling temperatures during the afternoon. Rain
showers will change to snow showers during the afternoon and
evening, with continued decent coverage provided by support from
the passing upper trough. Best coverage will be north of
Pittsburgh , but non-favorable trajectories and an icy Lake
Erie will negate any lake enhancement. Still, around an inch is
possible near and north of I-80 and perhaps on the higher
southeastern ridges, with little or no accumulation elsewhere.


A few snow showers will linger into Wednesday, but building high
pressure will shut off most of the precipitation by Wednesday
evening. Dry weather is forecast for Thursday and Friday, with
temperature moderation back above normal by the end of the week
as the upper ridge crosses. Another trough emerges from the
Plains next weekend with the next chance of rainfall.


While some improvement has been observed at the TAF sites south
of KFKL and KDUJ, expect this to be short lived with prevailing
IFR and low MVFR conditions in stratus across all terminals
again tonight. A little uncertain to the extent of fog, but
opted to take a persistence type forecast, albeit slightly more
optimistic, with scattered showers/drizzle anticipated.

Deep low level moisture will finally lift northward tomorrow
with the warm front, which should return VFR to all sites by
late afternoon.

A WSW wind will persist through the period, and generally stay
below 10kts

Restriction potential continues Monday night with the passage of
a cold front.




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