Area Forecast Discussion
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FXUS61 KPBZ 200746

Area Forecast Discussion
National Weather Service Pittsburgh PA
346 AM EDT Tue Mar 20 2018

A wintry mix of precipitation is expected today with low
pressure. The mix should change to snow tonight before gradually
tapering off Wednesday.


A wintry mix of precip should overspread the region mainly S of
I 80 today as low pressure tracks across the TN and OH Valley
regions. Warm advection ahead of the low should result in mainly
rain or a rain snow mix S of I 70 outside of the higher
terrain. Rain and snow is expected N of I 70, along with a
brief, slight chance for freezing rain. Little if any
accumulation of ice or snow is expected with marginal
temperatures and the high March sun angle, though the colder
Laurel Highlands could see an inch or two of snow. Some model
progs appear to be too high with high QPF/snowfall due to
overdone strong omega bullseyes in warm advection.

The higher terrain of WV and MD should see snow and freezing
rain transition to mainly snow today. Will maintain the Winter
Storm Warning for the expected snow and ice accumulations, with
temperatures more favorable for accumulation with cold E upslope

Precip should decrease in coverage this afternoon as the best
upper support and lift exits.


A second low is progged to dig across the OH/TN Valleys tonight
and part of Wednesday. Cold advection in the wake of the initial
Tuesday low should result in all snow across the region.
Maintained the Winter Weather Advisory and the Winter Storm
Warning with accumulation expected as temperatures drop below
freezing at night. Expecting generally 2-4 inches total for
areas S of I 80, with amounts from 6-12 inches in the higher
terrain where the Winter Storm Warning is in effect.

The snow should taper off from N-S Wednesday as lift/upper
support shifts off the E Coast with a developing coastal low.
Dry weather returns with shortwave ridging Wednesday night and
Thursday. Below average temperatures are expected to continue.


Surface ridging should maintain dry weather until a srn stream
low returns rain and snow chances S of I 80 Sat thru early Sun
night. Limited POPs to chance with a significant model shift swd
with the low in recent solutions. An Ern CONUS ridge should
return dry weather later Sun and part of Mon before a Midwest
trough returns low precip chances late Mon.


VFR conditions are expected through the predawn hours although
high cigs wl lwr with the approach of low pressure. Condition
deterioration will occur from the south after daybreak as that
low shunts moisture over the region. Expect general MVFR with
pockets of IFR visibility, with continued degradation to
widespread IFR during the afternoon.

Restrictions, albeit with gradual improvement, are likely into
Thursday morning.


MD...Winter Storm Warning until 8 PM EDT Wednesday for MDZ001.
OH...Winter Weather Advisory from 8 PM this evening to 8 PM EDT
     Wednesday for OHZ039>041-048>050-057>059-068-069.
PA...Winter Weather Advisory from 8 PM this evening to 8 PM EDT
     Wednesday for PAZ013-014-020>023-029-031-073>075.
     Winter Storm Warning from 8 PM this evening to 8 PM EDT
     Wednesday for PAZ076.
WV...Winter Weather Advisory from 8 PM this evening to 8 PM EDT
     Wednesday for WVZ001>004-012-021-509.
     Winter Storm Warning until 8 PM EDT Wednesday for WVZ512>514.
     Winter Storm Warning from 8 PM this evening to 8 PM EDT
     Wednesday for WVZ510-511.


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