Area Forecast Discussion
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FXUS61 KPBZ 210053

Area Forecast Discussion
National Weather Service Pittsburgh PA
853 PM EDT Sun May 20 2018

After a brief stretch of dry weather, the chance for rain
returns late Monday into Tuesday. Conditions should dry out by
Wednesday and stay that way through Thursday. Unsettled weather
returns for the holiday weekend.


No changes needed for the evening update. Forecast is in good
shape. Previous discussion below:

Scattered storms remain south of our West Virginia counties as
the surface boundary continues to push south of the Mason Dixon
line. Forecast challenge for this time frame is the development
and aerial extent of fog? Surface dewpoints continue to lower
into the upper 50s across most of Pennsylvania and eastern Ohio,
This places values near the cross over temperature which
indicates potential for fog development. With only a few hours
of clearing this afternoon, there is still plenty of low level
moisture. Therefore, will continue trend of patchy fog for all
areas overnight.

A warm front ahead of an mid western cyclone moves through
during the afternoon hours. Atmosphere will be too stable to
ignite any pop up shower or storm until its passage. Confined
pops for the daylight hours across eastern Ohio and the northern
WV panhandle and that won`t be until the afternoon.


The front that has stalled out to the south will be brought
back to the north by a wave of low pressure moving to the
northeast. The low pressure will be over western Ohio Monday
evening and over Lake Erie by Tuesday morning. The highest
chances for precipitation will be during the Monday
night/Tuesday period and have continued likely pops. This front
which has been in and around the region for more than a week
should finally move definitively to the south Tuesday night into
Wednesday, allowing for a period of dry weather. Temperatures
will be a few degrees above normal.


Surface high pressure should allow for dry weather over multiple
days before the chance of rain returns for the weekend with low
pressure moving over the Great Lakes. Have maintained likely
pops on Sunday with the passage of a cold front. Temperatures
should remain a few degrees above normal.


High confidence forecast save for visibilities during the
predawn hours where they could be lower than forecast.

VFR weather will continue most of the forecast period. With
temperatures cooling back, patchy fog will develop in the 8z-
12z time window. Any fog will quickly dissipate and yield to
VFR weather. Diurnal cumulus again will develop in the
afternoon. As a warm front approaches from the west, showers and
storms will approach, however coverage and onset time resides
at the end of the forecast period and was not included.

Winds will be light from the north then become light and
variable tonight through Monday.

No widespread IFR weather is expected.




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