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-- Discussion containing changed information from previous version are highlighted. --
073
FXUS61 KPBZ 161522 AAB
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
1122 AM EDT Wed Oct 16 2019

.SYNOPSIS...
A strong cold front will bring rain to the area through mid-day.
Much colder air will overspread the region behind the front, keeping
temperature below average through Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Light rain continues ahead of and behind the sfc frontal zone, while
a focused region of moderate rain is found along a narrow band in the
vicinity of the frontal zone where low-level convergence is
maximized. Mid-level dry air is wrapping into the system from the
west, which will lead to a rapid erosion of post-frontal rain this
afternoon and a brief break in clouds.

Strong cold air advection will ensue behind the boundary, leading to
steady to slowly dropping temperature this afternoon and steepening
low-level lapse rates. As a result, gusty nwly wind can be expected
by mid-afternoon area-wide. A low-level jet will strengthen as
tonight approaches, leading to stronger wind speed overnight at the
highest elevations.

The break in clouds will be self-defeating, as any sun will result in
rapid destabilization and increasing coverage of stratocu by late
this afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
Wind Advisory was expanded to include the ridges of Garrett County
with reasoning of previous forecast still applicable. Gusty nwly wind
amid strong cold air advection in the wake of the cold front
currently crossing the region will support deeper mixing and
consequent momentum transfer to higher elevations. Wind still is
expected to gust in the remaining ridge zones, but likely will remain
below 40 kt except for perhaps very limited locations. Previous
discussion follows...

The main trough axis will swing a secondary front through the region
this evening. The forcing with the boundary, and atmospheric
destabilization from the cold air aloft, will promote the creation
of scattered showers in the front`s wake. The risk for showers will
continue overnight as another shortwave trough dives southward in the
northwest flow aloft.

Strong wind gusts will continue overnight and through Thursday
morning. An impressive mid-level jet will dive southeastward on the
back side of the eastward moving trough. Most of the winds will not
mix down to the surface, but in the highest ridges of WV winds won`t
need to mix down very far to reach the surface. Have issued a wind
advisory tonight into early Thursday afternoon for Eastern Tucker
county. Garrett county may need an advisory as well, and this can be
determined as new model data arrives.

Thursday will feel like late fall with clouds, below normal
temperatures, and scattered rain showers.

Models are indicating that snow showers are possible over the ridge
tops Thursday. Forecast thicknesses and soundings are not showing an
optimal setup for snow creation. Low-level thicknesses are a bit too
warm and the soundings show a saturated layer well below the snow
growth zone. No ice will be falling into the saturated layer, as the
air above 5000ft will be dry, which will further make dendrite
creation difficult. As strong orographic lift continues into Thursday
afternoon, saturation heights may increase just enough to support
some snow, but even the top of the cloud layer remains warmer then
-7c. A forecast of rain or snow looks good for the ridge tops.

Very little change in the pattern until Friday afternoon, when the
cold pool aloft finally modifies and begins to drift eastward.

Shower coverage will decrease Thursday night as inversion levels
lower.

Have held onto clouds a bit longer on Friday as warmer air to the
west will be held at bay until the mid-level ridge gets here.

This additional cloud cover will also support lower highs on Friday.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A building ridge will lead to dry weather through the weekend, along
with a warming trend. High temperatures will again reach the mid to
upper 60s Saturday and Sunday.

The models are indicating that yet another dynamically-strong system
will develop over the Plains on Sunday/Sunday night and lift across
the western Great Lakes through Tuesday. Details are still in
dispute this far out, although increasing rain chances are certainly
indicated for early next week.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
VFR, with local MVFR/IFR conditions will prevail in showers and a
few isolated thunderstorms early on. A frontal passage through 18Z
will bring a dry slot through the region, with a temporary return to
VFR at all terminals. MVFR and scattered showers return this evening
through tonight in W-NW flow.

After FROPA, an increasing pressure gradient, mixing, and cold
advection should result in gusty W wind from 20-25kt. These gusts
should continue through tonight.

.Outlook...
Restrictions are possible Thu under NW flow and upper troughing.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...Wind Advisory from 6 PM this evening to 2 PM EDT Thursday for
     MDZ001.
OH...None.
PA...None.
WV...Wind Advisory from 6 PM this evening to 2 PM EDT Thursday for
     WVZ514.

&&

$$