Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 161947
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
347 PM EDT Wed May 16 2018

.SYNOPSIS...
High pressure wedged across the lower lakes between a quasi-
stationary front across the Ohio River Valley and a cold front
across the northern Great Lakes. It will be this cold front that
will quietly sink south across the area Thursday. Low pressure
across the lower Ohio Valley will slowly move northeast reaching
the local area on Saturday.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
Area wedged between high pressure across the Great Lakes and a
quasi-stationary front across the Ohio Valley with a weak
inverted trough extending up across eastern OH. A few
showers/sprinkles still possible from southeast of a Medina to
Conneautville PA line this evening. This should be over my mid
to late evening. Will keep some residual cloud cover overnight
across the southeast. Patchy fog a possibility especially if we
clear out better. Slightly drier air works southward Thursday
with a gradual clearing/thinning of the cloud cover for most
despite the passage of a weakening cold front. Will keep the
slight chance of a shower across the extreme southern portions
of the area where low level moisture lingers. Temperatures other
than along the immediate lakeshore will still be running above
normal in the mid/upper 70s. If we do not clear out as well,
then temperatures can be a half dozen degree cooler. Allowed a
few showers to encroach on the southern counties late Thursday
night as the upper low across the lower Ohio Valley begins to
drift northeast and the surface front becomes more active. Night
lows both tonight and Thursday night will be mild in the 50s.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Overall upper level pattern trending toward becoming sort of
sluggish as a system over the Gulf of Mexico begins to make a
slow trek north toward the forecast area. The weak surface low
and upper level trough of low pressure will be centered over the
local area by Saturday. The low will move off to the northeast
on Sunday and a trailing cold front will sag south across the
area where it will become nearly stationary by Sunday night. As
of now, it appears the front will not make much progress south
of Lake Erie so we should remain in the warm sector through this
forecast period.

Atmosphere appears it will be fairly stable as the leading edge of
the precipitation expands northward ahead of the weak storm system
Friday.  Will limit precipitation to just showers or just plain old
rain Friday.  Then, as the center of circulation arrives over the
forecast area, a surge of warmer air will push north causing some
destabilization over the area.  The best chance for thunder appears
it will be over the eastern half of the forecast area by Saturday
afternoon. So, will mention a chance of thunderstorms into Saturday
night.  More stable air arrives Sunday and could suppress thunder
activity but until track of the low is more defined will keep a
mention of the thunder for now.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
The models look in relative agreement with the big picture early
next week but the minor discrepancies at the surface just happen to
be near the forecast area, namely the timing of the next front and
whether there may be a wave on the front. Heights are not progged to
drop much as the trough aloft is progged to be shallow and aimed
more toward eastern Canada/New England. The GFS is especially slow
in dropping the heights and pushing the surface front south. All
this would seem to indicate a slow frontal passage is reasonable.
The models also have a look of convective feedback and while it
would be reasonable to continue to include showers in the forecast
through Monday night given a slow frontal passage, I am not inclined
to go too high on the pops since I do not have much confidence of a
surface wave or the strength/track of the potential wave.

Will keep Tuesday dry for now. Eventually the surface high progged
to build over the Great Lakes and eastern Canada has got to push
some dry air southward although admittedly it could take until
Wednesday.

Forecast temperatures will not be far from the blended model
guidance given the uncertainty in timing. By Monday, the front may
still be north of the area with temperatures in the lower 80s or the
front may be south of the area with temperatures in the 60s. Highs
Tuesday and Wednesday will be near seasonable normals.

&&

.AVIATION /18Z Wednesday THROUGH Monday/...
High pressure will exert greater influence through tonight and
into Thursday. This will keep showers largely south of the
terminals; just clipping CAK/YNG this afternoon. VFR conditions
will be predominate with the exception of the pre-dawn hours
Thursday with some MVFR vsbys possible for CAK/YNG. Fog on the
lake this past morning hugged the shoreline. Models cluing in
on this possibility for Thursday morning as well near ERI, but
low confidence. Northeast flow goes light/variable tonight and
picks back up around 10 knots Thursday.

OUTLOOK...Non VFR possible Friday and Saturday in
showers/thunderstorms.

&&

.MARINE...
Winds on the lake are expected to be light and variable through
Thursday and then begin to increase out of the northeast as the low
pressure system pushes north toward the area.  Winds will increase
to 20 knots across the lake Thursday night and continue into Friday
morning.  Will likely need a small craft advisory for this period.
Light and variable winds return Sunday as low pressure pulls out to
the east and stationary front settles in over the lake.  Very little
change is expected through Monday with presence of the stationary
front nearby.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.

&&

$$
SYNOPSIS...Oudeman
NEAR TERM...Oudeman
SHORT TERM...Lombardy
LONG TERM...Kosarik
AVIATION...Oudeman
MARINE...Lombardy



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