Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 201554

Area Forecast Discussion
National Weather Service Cleveland OH
1154 AM EDT Tue Mar 20 2018

Low pressure over eastern Kentucky early this morning will move
off the Middle Atlantic Coast this afternoon. A piece of low
pressure will linger near the Ohio River Valley tonight into
Wednesday waiting for low pressure to move up the East Coast of
the US. High pressure should build into the area for Thursday
and Friday.


Update...Tweaks for afternoon temps made on the update. Sky
grids also adjusted but no big changes there.

Previous Discussion...
Difficult forecast today with low pressure over eastern
Kentucky moving off the Middle Atlantic Coast this afternoon.
Some precipitation is attempting to move northward toward Mid
Ohio but is having a difficult time as it interacts with dry air
that resides over northern Ohio and NW PA. There will end up
being a very tight gradient of precipitation as it moves ever so
slowly northward through the morning. Evaporative cooling with
the onset to the precipitation that moves into the region from
the south this morning should be enough to cause sleet or snow.
As we progress into the afternoon it appears we will warm enough
to change any remaining light wintry mix into rain. So no
issues are expected through the day.

However as another piece of jet energy dives into the upper
level trough that resides over the area tonight we should see an
increase in the coverage and intensity of the precipitation.
After sunset the atmosphere should chill enough for all snow.
The northward extent of the snow will remain a difficult call
with the dry air still working on the northern edge of it. For
now will limit the more significant accumulations of snow to an
area near and south of US 30. This area will have the potential
of getting very close to 4 inches of snow. So with that said we
will issue a Winter Weather Advisory. The heaviest accumulations
will occur from 03Z through 12Z then taper off through
Wednesday morning.

It will be cooler today with highs in the mid 30s to around 40.
Similar ranges are expected on Wednesday, coolest where snow
accumulations occur tonight.


Deep troughiness will take place over the eastern United States as a
series of upper level low pressure systems move across the area.  An
initial upper level low pressure system will move east out of the
Ohio Valley to the east coast Wednesday night into Thursday. A
secondary upper level low pressure system will dive southeast across
the area Thursday night.  This low will help to enhance the upper
level trough over the eastern U.S.  An upper level ridge of high
pressure will build across the central United States and then shift
east over the local area by the end of the week.

Cyclonic flow around the surface low exiting to the east coast will
persist through Wednesday night and Thursday.  A surface ridge will
build east toward the area with the upper level ridge Thursday night
and persist through Friday night. The exiting low and approaching
ridge will bring a return to fair weather across the forecast area
during this period.

Temperatures are expected to remain nearly steady from day to day
and night to night through this forecast period.  No real push of
warmer air will take place at this time.  High pressure ridge will
take its time moving east across the area. Surface flow will
continue from a northerly component keeping the warm air at bay.


A weak shortwave will move southeast along the eastern side of the
upper level ridge Saturday into Saturday night.  This feature will
force a low pressure system to move toward the forecast area with a
warm front extending east from the low.  Moisture associated with
the storm system will begin to spread into the forecast area
Saturday and bring another threat for some precipitation.  Best
chance looks like it will arrive late Saturday into Saturday night
in the form of snow.  Low pressure and the associated moisture pull
out to the east and southeast on Sunday.  Another ridge of high
pressure will build east across the forecast area aloft and bring
another round of fair weather back to the local area Sunday through
Sunday night.  Yet another low pressure will race northeast and
bring with it a chance for some rain come Monday.

A little bit of warmer air will arrive gradually by Monday as flow
shifts around to the east and southeast.  So, a slight warming trend
is expected through the period.


.AVIATION /12Z Tuesday THROUGH Saturday/...
VFR conditions will continue through the morning at most
locations. However ceilings will slowly lower from south to
north through the day as precipitation spreads northward. We
will have to monitor how far north the precipitation can get
this morning as it interacts with the drier air over northern
Ohio. At this point we believe that any precipitation that
occurs this morning across Mid Ohio will be very light and would
be either sleet or snow.

The southern TAF sites should begin to see MVFR conditions late
this afternoon into the evening when the better chances or
precipitation arrive. All locations should change over to snow
by sunset with accumulations possible at KMFD and KCAK. These
southern TAF sites will have the best chances of seeing IFR
conditions overnight with the snow.

.Outlook...Non-VFR late tonight through Wednesday morning at
most locations in -sn.


Water levels on the Western Basin are already high and are
expected to remain that way into Wednesday morning. Will go with
a lakeshore flood warning for Ottawa and Lucas counties.

Small craft advisory will remain in effect through Wednesday morning
in the western basin and through Wednesday afternoon over the rest
of the lake.  Winds are expected to remain gusty across the lake
today and will increase and approach gales for about 6 hours
tonight.  Coordinated with Toronto and Buffalo an agreed to hold off
on issuing gale warnings at this time since gale force winds will be
brief.  Expecting winds to gradually weaken Wednesday across the
lake to allow small craft advisory to expire on schedule.  Winds
will gradually diminish with time to around 10 knots by Friday and
Saturday. No significant winds expected beyond Wednesday.


OH...Lakeshore Flood Warning until 10 AM EDT Wednesday for OHZ003-
     Winter Weather Advisory from 8 PM this evening to 11 AM EDT
     Wednesday for OHZ029>033-036>038-047.
MARINE...Small Craft Advisory until 4 PM EDT Wednesday for LEZ144>149.
     Small Craft Advisory until 10 AM EDT Wednesday for LEZ142-143.


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