Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 232331

Area Forecast Discussion
National Weather Service Cleveland OH
731 PM EDT Tue May 23 2017

High pressure centered along the mid Atlantic coast will move
off the coast tonight. Low pressure will slowly move from the
Mississippi Valley across the Great Lakes Wednesday and
Thursday. High pressure will briefly build over the region late
Friday. A warm front is expected to develop over the Ohio
Valley by Saturday. The next cold front should arrive by Sunday.


Only adjustment to the forecast this evening was to slow the
arrival of the clouds. High clouds have been increasing but
several areas will see partly cloudy conditions this evening
before thickening.

Previous discussion...Kind of a busy weather map. The main
trough/upper low was over Iowa diving south. A weak short wave
over the midwest will lift north and the precipitation over the
midwest should stay west and north of the forecast area early
tonight. A short wave over the southern Appalachians was moving
NNE. Many of the models have been persistent in posting small
amounts of QPF over NE OH and W PA later tonight and despite the
dry SE downslope flow in the boundary layer, I could see a few
showers coming out of the mid level clouds later tonight into
early Wednesday across NE OH and NW PA. Condensation pressure
deficits take until 09-12Z on the NAM to become nearly saturated
so it may be a challenge to overcome the dry boundary layer.
Have included a small pop (15-30) after midnight for NE OH and

Dew points are low and winds will be rather light but clouds will
increase tonight. Lows should be some 5-10 degrees warmer than
last night. Forecast lows will be near guidance which is
bunched mostly in the mid 50s.


Not sure how the precipitation will evolve on Wednesday. There
could be a few morning showers NE OH/NW PA but the main event
will be the approach of the upper low and associated surface low
by Wednesday afternoon. The models continue with a variety of
solutions as far as the surface low. Some solutions develop a
relatively deep surface low, almost looking as though from
convective feedback. The forecast will just gradually increase
the pop from southwest to northeast on Wednesday with the
majority of the rain from Wednesday afternoon into Wednesday
night. Highs Wednesday are tricky. Temperatures could warm into
the lower 70s perhaps even mid 70s where the rain is slow to
arrive. Temperatures cold hold in the 60s if it is cloudy and
rain arrives quickly. The forecast will split the difference.

There remains some suggestion of a dry slot Wednesday night which
may be reasonable but did not try to get very specific with the
forecast just yet.

Likely or categorical pop on Thursday for showers under the upper
trough/low. If there is a dry slot, it may take a while for the
showers to fill in.

The GFS is faster lifting out the upper low on Friday. Not sure I
buy it just yet. Will keep a small chance for showers mainly over
NE OH/NW PA. High temperatures will recover toward normal.


Starting Sat, the upper pattern may have some weak ridging but a
surface frontal boundary should be near the area to provide a focus
for shra and tsra. Sun thru Tue the next s/w rotates se into the
upper trough to re-amplify the trough over the lakes. This will lead
to unsettled weather with chances for shra and maybe possible tsra
while near normal temps trend back below normal.


.AVIATION /00Z Wednesday THROUGH Sunday/...
Ceilings will be lowering with time over the next 24 hours as a
result of an upper level low pressure system that is expected to
dive south into the deep south by Wednesday afternoon. This will
force a low pressure system at the surface to move north toward
the Ohio valley region during the same period. This will cause
rain to move into the area from the southwest with time.
Visibilities could drop as low as MVFR by tomorrow afternoon and
ceilings most areas down to MVFR and then possibly IFR by the
end of the period.

OUTLOOK...Areas of Non-VFR through Thursday in showers and
possible Thunderstorms and again for the weekend.


Low pressure will develop over the IL/IN area tonight but remain
nearly stationary until slowly moving ne across Lake Erie early Thu
night and off the New England coast by late Fri. This will lead to
increasing ne winds of about 10 to 20 knots for Wed that should
become more east to se for Wed night then mainly sw then west Thu
into Thu night. As colder air pushes across the lake Thu night and
Fri there could be a period of near SCA conditions before winds
diminish to 10 knots or less by Fri evening and start to back to
south then east ahead of the next low that should move near the lake
Sat night.




SHORT TERM...Kosarik
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