Area Forecast Discussion
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FXUS61 KPBZ 211018

Area Forecast Discussion
National Weather Service Pittsburgh PA
518 AM EST Sun Jan 21 2018

Warming temperatures and patchy light rain will be interrupted
by a Monday night cold front.


Cosmetic changes only were necessary for the predawn update as
drizzle and light rain have developed as anticipated.

Warm,moist advection will continue today over the Upper Ohio
Region as the area is in the broad eastern flank/warm sector of
deep low pressure emerging from the Four- Corners Region. No
real changes were needed for the near term forecast as chances
for light rain were maintained with a temperature forecast about
10 degrees above the averages.

Despite abundant cloud cover, condensational heating from the
increasing boundary layer dampness will escalate the melt of the
remaining snowpack and aid the rot of river ice before more widespread
rain arrives late Monday. No flood-headlines are thus anticipated.


The aforementioned low is projected to deepen as it digs toward
the Great Lakes through Monday. Warm but damp weather can thus be
expected over the immediate area until that system pulls a cold
front across the Upper Ohio on Monday night. Precip probabilities
for Monday were adjusted for warm frontal positioning, a change
which features likely numbers(albeit still for light rain) for
northern zones during the morning followed by a transitional
period as the low to the west matures.

The low is projected across the Great Lakes by early Tuesday
with more widespread rain anticipated locally with cold frontal
passage on Monday night. Categorical POPs were maintained and
QPF is still limited to a half inch or less as per rapid system
progression and dry slot encroachment. That QPF limitation and
timing, along with the prior reduction in snowpack should alleviate
broad flood issues.

Seasonable temperature in the wake of the front is expected to
change rain showers to snow on Tuesday with upper support via
the crossing mid level trough. Progression and a relatively
warm boundary layer should limit accumulation potential before
snow shower chances taper off with building high pressure on


Building high pressure in advance of another low emerging over
the Plains is likely to dry and warm conditions before rain
chances return for next weekend.


Degraded conditions in the form of IFR, and occasionally MVFR
stratus can be expected with drizzle and light rain throughout
the TAF period as moisture advection continues on SSW wind.

Restriction potential continues for the first half of the week
with the approach and passage of a frontal system.




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