Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 170725
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
325 AM EDT Tue Apr 17 2018

.SYNOPSIS...
A large area of low pressure will slowly move east from the eastern
Great Lakes today into southern Quebec tonight. High pressure will
build east across the region tonight into Wednesday. Low pressure
will track east through the Great Lakes and Ohio valley region
Wednesday and Wednesday night, moving into New England by Thursday.
A large area of high pressure will slowly build east across the
region Thursday night through the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Broad cyclonic flow over the Great Lakes will keep temperatures
across the area below normal today and tonight. Ample synoptic
moisture and 850 mb temps in the -10C to -12C range bringing
some light lake effect snow showers across the region early this
morning. Most of these snow showers are inconsequential, however
some more organized bands downstream of Lake Erie across the
snow belt may be enough to drop accumulating snow, especially as
upstream PV anomaly/closed upper low tracks southeast from
northern lower Michigan early this morning into eastern Lake
Erie by mid day. Hi-res guidance has been very aggressive with
organized band development across the primary snow belt towards
and just after 12Z as the synoptic support arrives. Lake
induced CAPE of 200-400 j/kg and inversion heights approaching
7kft should be supportive enough for organized snow showers
through the morning hours, especially with the synoptic
enhancement. The biggest question is how organized the snow
showers/bands will be given rather paltry lake surface to 850mb
delta T values in the 12-14C range. Currently thinking the
period of more organized bands will be brief and limited to the
synoptic support, peaking around 15Z across the snow belt and
tapering off after 18Z as the PV anomaly tracks southeast out of
the area.

As far as snowfall amounts, went a bit higher with
totals through mid day, with general amounts up to/around and
inch in the primary and secondary snow belt, with trace amounts
elsewhere. Some of the higher terrain in the primary snow belt
could see higher amounts, but will be largely dependent on the
persistence/intensity of the snow showers given temperatures
near freezing and a high sun angle. Currently thinking most of
the accumulations will be on grassy surfaces, with potential
brief/intense snow showers putting a coating on untreated road
surfaces and quickly melting after the snow showers end.
Wouldn`t be surprised to see amounts in the 1 to 3 inch range
where the snow showers persist across northern Geauga county,
and possibly in the 2 to 4 inch range across inland portions of
Erie county PA. Snow showers activity will diminish quickly from
west to east through the afternoon, with a band or two possibly
lingering into the evening hours, especially across northwest
PA.

Went a degree or two cooler for highs
today, with mid to upper 30s across much of north
central/northeast OH and northwest PA, with highs around 40
across northwest OH. High pressure will build into the region
tonight, with any lingering lake effect snow showers diminishing
across northwest PA, and clearing skies across much of the area
outside of the lake shadow. Lows will be very cold tonight, with
mid/upper 20s to low 30s.

Attention turns to low pressure tracking east out of the central
MS valley Wednesday. This low is expected to track into western
OH by late Wednesday afternoon. Rain showers will move into the
area from the west through the afternoon hours. The 00Z
NAM/ECMWF seem to be just a bit slower and further south with
the surface low, while the 00Z GFS is faster and a bit farther
north. Have chance pops arriving early afternoon across western
areas, with low likely pops expanding eastward into the early
evening hours. Went a touch cooler for highs, ranging from the
mid/upper 40s near Lake Erie to the mid 50s south.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
Only minor changes to the short term period forecast today.  Strong
low pressure is still forecast to cross the area Wednesday night.
All of the new guidance takes the low just to the south of Lake
Erie.  Will see widespread showers ahead of the low and then wrap
around precip the second half of the night as the low speeds off to
the east.  Critical thicknesses will get cold enough for a possible
rain/snow mix late Wednesday night in the wrap around.  There should
be enough of a temperature rebound on Thursday to end the snow
threat even though lake effect showers will continue downwind of the
lake. It will again get cold enough for snow showers Thursday night
but by that time the lower atmosphere will be drying out and
anything more than a dusting of snow appears unlikely.  The lake
effect will finally end Friday as the dry air and high pressure win
out. Thursday will be another chilly today but temps will warm back
into the 50s for Friday.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
High pressure will settle over the region for the weekend and start
of next week.  Will go with a completely dry long term period as
high pressure dominates.  Temperatures will warm a couple degrees
each successive day and by Monday we will be back to within a couple
degrees of normal.  It`s hard to believe but normal highs are around
60 degrees this time of year.

&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
MVFR ceilings will prevail through most of the day with broad
cyclonic flow across the Great Lakes region. An upper low will
swing across the southern Great Lakes this morning, which could
bring some snow showers to terminals, with the best chances at
KERI and KYNG, and KCLE/KCAK to a lesser extent. Some IFR
visibility restrictions in snow showers cannot be ruled out.
SHSN potential will wane from west to east through the day,
ending everywhere but KERI around 00Z. Some clearing will work
into the area from the west towards the end of the period. West
winds will remain gusty through the day, generally around 25
knots, with some gusts subsiding after 00Z.

OUTLOOK...Non-VFR possible again late Wednesday night and
Thursday.

&&

.MARINE...
Winds in the western basin have diminished overnight which has
allowed water levels to rebound.  Will be able to get rid of both
the small craft advisory and low water statement in the west.
Further east...westerly winds will stay up in the 15 to 25 knot
range today and tonight.  We may even get close to 30 knots for a
time in the central basin today.  Winds will lessen tonight and
Wednesday morning before becoming northeasterly in the afternoon.
This will be in response to an area of deepening low pressure that
is expected to pass to the south of the lake Wednesday night.  A
cold front stretching west from the low will push south of the lake
early Thursday.  Strong northwest to north winds are expected behind
the front.  Strong northwest winds will continue through Friday
before finally weakening and becoming northerly Friday night.  On
Saturday the flow should become light and variable as settles over
the lake.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 4 AM EDT Wednesday for LEZ144>149.

&&

$$
SYNOPSIS...Greenawalt
NEAR TERM...Greenawalt
SHORT TERM...Kubina
LONG TERM...Kubina
AVIATION...Greenawalt
MARINE...Kubina



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