Area Forecast Discussion
Issued by NWS Cleveland, OH

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817
FXUS61 KCLE 171711
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
1211 PM EST Sun Dec 17 2017

.SYNOPSIS...
A weak low moving northeast into Lower Michigan tonight will pull a
warm front near the south shore of Lake Erie north into Canada. A
cold front will move east across the region Tuesday then high
pressure will spread southeast from central Canada into the area by
late Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
No significant changes to forecast for 1230 update. Tweaked
temps up another couple of degrees south of warm front.

Original discussion...
Areas of stratus and fog will be present for a while this
morning until daytime heating and increased winds dissipate the
fog by late morning. Some of the fog may be locally dense.
Freezing temps early will allow for icy spots on roadways that
are wet.

A series of weak upper and surface lows will quickly move east
across the region later today/early tonight and on Monday. Moisture
with these systems is marginal so only expecting areas of light
precip and the models continue to differ on where the better chc for
the precip will be.

Temps are expected to warm just enough for most of the precip to be
rain but a little wet snow could mix in, especially around the
higher terrain of NW PA. Most of the area should see lows tonight
stay above freezing but some of the normally colder locations such
as BJJ and inland NW PA could see 32 or 31 which may produce some
icy spots by the end of the night. Highs today should mainly be 35
to 40 then a couple degrees warmer on Monday.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The short term forecast begins on Monday night with mostly zonal
flow in place, as the forecast area finds itself between two systems
with low pressure off to the north and high pressure off to the
south. The forecast for this period has consistently had a slight
chance to low chance pop, as the guidance shows a piece of energy
streaming through the region. In addition, there is ample moisture
as low-level winds from the south will pool some moisture in with
dew points in the upper 30s. However, confidence in widespread
precipitation occurring during this period is not very high with the
zonal flow aloft and lack of a forcing mechanism so will leave much
of Monday night into early Tuesday unchanged for now. Temperatures
will be well above normal for Monday night and Tuesday

For Tuesday afternoon and beyond, the aforementioned low pressure to
the north will extend a cold front across the area during the latter
half of Tuesday. Rain will change over to snow as temperatures drop
back down below freezing on Tuesday night. The winds will shift
around to the west and allow for lake-effect conditions in the snow
belt region. The conditions for some lake-effect look a bit better
for Tuesday night than they did during the forecast package
yesterday morning. However, dry air will quickly move into the area
on Wednesday and shut down the lake-effect before anything headline
worthy occurs. High pressure will move in at the surface for
Wednesday and will allow for seasonable dry day across the region.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The long term begins on Thursday with high pressure sliding off to
the east. Compared to yesterday`s model runs, the next system that
will approach the area for the end of the week has slowed
significantly. The system likely won`t reach the area until the
second half of Friday with the region in the warm sector for the
entirety of Thursday and the first half of Friday. Therefore, have
bumped up temperatures for the first half of the long term and held
off precipitation until after 12z Friday.

Low pressure will move through Friday night and Saturday with the
cold front clearing the area sometime Saturday early afternoon.
While there is some uncertainty on the onset of the precipitation
for the end of the week, there has been much consistency in Friday
night and Saturday being a wet period so have likely pops through
those time periods. Precipitation will begin as rain and then chance
over to snow has the low and cold front move through and
temperatures drop below freezing. Westerly flow over Lake Erie will
then allow for lake-effect to set up over the snow belt for Saturday
night.

&&

.AVIATION /18Z Sunday THROUGH Friday/...
Some light rain moving up from the Ohio Valley as low pressure
over Iowa drift north. Expect IFR cigs/vis to develop late
tonight as boundary sags over the forecast area.

OUTLOOK...Non-VFR expected Monday in -ra/dz. Non-VFR also
possible northeast OH and northwest PA later Tuesday into
Wednesday.

&&

.MARINE...
High pressure off to the north are allowing for mostly light
easterly winds for today. Winds will remain rather light but will
flip around to the south Sunday night into Monday as low pressure
moves northwest of the area for Monday. The low will increase the
pressure gradient over the lake and winds will increase to 10 to 20
knots. On Monday night, the low moves off to the northeast and a
cold front approaches the area. Winds will increase to 25 knots and
winds will shift slightly to the west as the front approaches closer
for Tuesday. A small craft advisory will be likely from Monday night
through Wednesday with strong southwest winds and waves building to
3 to 6 feet or higher through that period. High pressure building to
the south on Thursday will ease the winds over the lake and shift
winds around to the south for the end of the week.

&&

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

&&

$$
SYNOPSIS...Adams/DJB
NEAR TERM...Adams
SHORT TERM...Sefcovic
LONG TERM...Sefcovic
AVIATION...DJB
MARINE...Sefcovic



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