Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 210235
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
935 PM EST Tue Feb 20 2018

.SYNOPSIS...
A cold front will move east across the area late tonight through
Wednesday. As the front settles just south of the area, low pressure
will track northeast along the front Wednesday night through
Thursday. The front will lift back north through the area as a warm
front Thursday night into Friday as another low pressure system
develops and tracks northeast into the Great Lakes.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
No significant changes for the 930 update. Low pressure now
centered over Northern Lake Huron with the leading edge of the
cold front into NW OH. Wave entering Mid Mississippi Valley will
slow the progression of the front.

Original discussion...
Rain chances are taking a pause across the area late this
afternoon, as much of the early afternoon precip has lifted
northeast out of the forecast area. Rain chances will increase
from the west later this evening through the overnight as a cold
front pushes towards the area. Kept a mention of slight chance
thunder in the grids through 06Z, although instability and
forcing will be diminishing, and upstream lightning trends have
greatly diminished. The front will push through the area, with
rain continuing behind the surface frontal passage for a period
of time tonight through Wednesday. Only minor changes to pops
and hourly temperature trends from the previous forecast. Will
keep the Flood Watch up for Lucas County for this forecast
update, however flooding risk has greatly diminished, with
additional rainfall amounts tonight of a half to three quarters
of an inch. The heaviest rainfall will occur along and just
ahead of the front, but only light to occasionally moderate rain
is expected behind the front.

Main forecast challenge for this period is Wednesday night in
the wake of the surface cold front. Surface temperatures are
expected to fall to around 30 degrees across much of the area,
with some upper 20s possible across the northern part of the
area. A wave of low pressure will track northeast along the
front through the Ohio valley, with precip overspreading the
area from southwest to northeast, and greatest precip chances
across the southeast part of the forecast area. P-type issues
and impacts will remain fairly tricky, with rain expected south
of the surface boundary where temps will remain above freezing,
a thin line of mixed precipitation just northwest of the front,
and then light snow further north, if any precip makes it that
far north. This thin transition zone is the main concern, with a
period of freezing rain and sleet possible. Forecast soundings
support freezing rain, but north/northeast flow will usher in
fairly dry air into this transition zone, so expecting some wet
bulbing to occur as the precip saturates the column. This may
support more of a partial melting and more of a sleet/snow
concern vs. freezing rain. Compounding the impact uncertainty,
ground temperatures will be fairly warm where freezing rain
potential exists, after record high temperatures today. Any
freezing rain impacts may be limited to overpasses and elevated
surfaces at this point, with other road surface impacts being
fairly limited if existing at all. Any snow/sleet accumulations
should be less than an inch through early Thursday morning.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Abundant moisture will continue to stream northeast into Ohio
on Thursday as strong upper level high pressure sits off the
Carolinas coastline while a broad upper trough dominates the
Great Basin. Cold air will begin to slowly settle south with
snow possible generally across the northern half of the area and
a wintry precipitation mix across the southern half of the
area. The best chance for this wintry precipitation mix will
occur early Thursday morning through around noon on Thursday. We
will continue to fine tune details leading up to Thursday
morning as the GFS is a bit faster than the ECMWF with
precipitation timing.

Either way...expect generally an inch or less of snow across the
northern portion of the area and only minor accumulations of
freezing rain and/or sleet across the southern portion.

After the brief cool down on Thursday...a warming trend is expected
Friday into Saturday with temperatures generally in the mid 40s to
mid 50s as 850 mb temperatures rebound to nearly 10 C.

A few rounds of rain are expected to impact the area Friday and
Saturday...with subtle timing difference between the GFS and ECMWF.
Either way there will be at least a chance of precipitation from
Friday morning through Saturday.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Precip will be ongoing at the start of the period as the last in a
long series of low pressure systems impacts the area.  The surface
low will move northeast across the central Great Lakes Saturday
night into Sunday forcing a front across the local area. The usual
difference is the track and timing of the main features exist but
this will have little impact on the practical weather. It`s going to
rain everywhere and some of the rain...especially at the southern
end of the area could be heavy.  The rain should end from west to
east Sunday afternoon and evening.  High pressure will move over the
region for the start of the new workweek and Monday and Tuesday but
should be dry.  Temperatures will be cooling during the period but
will still be a little above normal on Tuesday.

&&

.AVIATION /00Z Wednesday THROUGH Sunday/...
Rainshowers will move over Western half of forecast area
overnight ahead of approaching cold front. Enough shear for
isolated TSRA possible NW OH. LLWS possible early this evening.
Surface winds have decoupled and 925mb winds 20040-45kt. The 925
MB winds will increase to 50kt overnight but expect surface
winds to pick up by then.


OUTLOOK...Non-VFR Wed morning ins -shra. More Non- VFR Fri and
Sat with the next front.

&&

.MARINE...
Brisk south to southwest winds will continue tonight ahead of a
slow moving cold front. The front will cross Lake Erie
Wednesday morning and winds will shift to northwest and north.
Wind speeds should diminish relatively quickly within a few
hours of frontal passage. Winds will veer all the way to ENE as
high pressure slides across eastern Canada into the weekend. A
cold front will cross the lake on Sunday and winds will become
southwest and a more seasonable and drier air mass will spread
across the lake early next week.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Flood Watch through Wednesday afternoon for OHZ003.
PA...None.
MARINE...None.

&&

$$
SYNOPSIS...Greenawalt
NEAR TERM...DJB/Greenawalt
SHORT TERM...KEC/Riley
LONG TERM...Kubina
AVIATION...DJB
MARINE...Riley



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