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-- Discussion containing changed information from previous version are highlighted. --
914
FXUS61 KCLE 140139
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
939 PM EDT Sun Oct 13 2019

.SYNOPSIS...
A weak cold front will push east across the southern Great
Lakes tonight into Monday. High pressure will build east across
the area Monday through Tuesday. Strong low pressure will move
east across the Great Lakes Tuesday night through Wednesday,
forcing a cold front across the area.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
Most of our near-term forecast was left unchanged. Latest
surface observations indicate the cold front extended
southwestward from the northwest tips of Lake Erie and Lucas
County, OH to far west-central IN. This front is forecast to
cross the rest of our CWA through about 5 AM EDT Monday morning.
The cold frontal passage will likely be a dry one for most
locations. However, a few lake-enhanced rain showers may form as
the front traverses central and eastern Lake Erie and come
ashore in the snowbelt region. The best potential for these few
showers exists from about midnight through the first few hours
of Monday morning. Behind the cold front, cold air crossing
relatively-warm Lake Erie is still expected to trigger lake-
effect rain showers in our snowbelt counties. These showers
could be heavy at times during the late morning and afternoon,
when lake-induced equilibrium levels near 10kft AGL and limited
vertical wind shear within the lake-effect cloud layer are
forecast to accompany lake-induced CAPE near 500 J/kg. During
this time frame, west-southwesterly mean flow within the cloud
layer and frictional low-level convergence along the southern
lakeshore should allow the rain showers to consolidate into a
single band along/near I-90 in our snowbelt counties. The lake
rain band should then break up into multiple bands of showers
and the rain should diminish altogether Monday evening as the
steering flow becomes westerly and a building high pressure
ridge causes lake-induced equilibrium levels to lower
considerably. Lake-effect rain totals are forecast to generally
be 0.10" or less, but up to 0.25" may fall in northern portions
of Erie County, PA. Made some minor adjustments to POPs and QPF
through Monday evening given latest available mesoscale model
guidance and our neighboring offices` thoughts.

PREVIOUS DISCUSSION...A large upper level and surface low
pressure system was near the upper Great Lakes region this
afternoon. This system is slowly moving eastward through
southern Canada. Gusty southwest winds this afternoon in
response to the surface low north of the region will relax a
little bit as the Sun goes down. There will be a gradual
increase in high and mid cloudiness moving in from the west and
northwest tonight and on Monday. A moisture starved cold front
will move across the area tonight with a wind shift to the west.
This front will be a dry frontal passage.

Temperatures at 850 mb will be dropping to 0C to 4C by Monday
morning. Monday will be a very cool, breezy, and cloudy day. A
band of lake effect rain showers will like develop during the
morning and impact areas in the primary Snowbelt region. Weak
high pressure will move in over the area Monday night with
clearing skies and temperatures falling back down in the 30s
away from the lake. Areas of frost look possible and some of the
colder valley areas could even see a light freeze Monday night.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
The short term begins with an upper level trough deepening into
a strong closed closed as it approaches from the upper Midwest.
As a result, a surface low develops over eastern Minnesota on
Tuesday. Meanwhile, the surface high pressure that has been
influencing the local weather will move off to the east, though
strong southerly warm advection will increase high temperatures
into the upper 60s for most areas on Tuesday, with mostly sunny
to partly cloudy skies. The surface low will deepen as it moves
east across lower Michigan and into southern Ontario by
Wednesday morning, forcing a cold front east across the area as
well. There won`t be a ton of moisture, but there will be enough
with the cold front and upper level forcing to produce
widespread showers Tuesday night into Wednesday morning.
Northwesterly flow begins on Wednesday evening after the cold
front passes to the east and the upper level low passes to our
northeast. Cold temperatures aloft, moisture from the upper
level low, and unidirectional flow will make it very likely that
lake effect precipitation occurs over Northeast Ohio and
Northwest Pennsylvania. MUCAPE of up to 500 J/kg will be
present, introducing the possibility for thunder on Wednesday
evening into the overnight hours. Low temperatures Wednesday
night will be in the low 40s, so precipitation type should be
all rain. Don`t worry, we aren`t expecting snow...yet.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Lake effect showers will persist through Thursday morning
before slowly diminishing throughout the day as the upper level
low moves off to the east and warm, dry air moves in from the
west over the lake. Surface high pressure and upper level ridge
moves east across the region on Friday, creating relatively
quiet conditions. An upper level trough moves through on Friday
night into Saturday, introducing a chance of showers across the
area on Saturday. The pattern becomes more amplifies on Sunday
with a deep trough building over the plains and upper level
ridging over the eastern CONUS. This means above average
temperatures expected, with upper 60s and lower 70s currently in
the forecast for Sunday afternoon.

&&

.AVIATION /00Z Monday THROUGH Friday/...
A weak cold front should cross the region from west to east
between about 01Z and 09Z/Mon. Primarily light surface winds
will shift from south-southwesterly to westerly with the passage
of this front. This wind shift will likely be most pronounced
along and near Lake Erie. In addition, this frontal passage will
likely be a dry one. Mainly clear skies ahead of the front will
give way to widespread VFR ceilings behind the front. These
ceilings should be most prevalent over and near Lake Erie. Lake-
effect rain showers are expected to affect KERI and vicinity,
especially between 12Z and 21Z/Mon. MVFR to IFR ceilings may
accompany these showers.

.OUTLOOK...Non-VFR in lingering lake-effect rain showers are
possible at/near KERI Monday evening. All TAF sites may
experience non-VFR in showers and isolated thunderstorms Tuesday
into Wednesday morning. Non-VFR are possible in lake-effect
rain showers at/near KERI later Wednesday into Thursday.

&&

.MARINE...
Have cancelled the western basin Small Craft Advisory early.
With the passage of the cold front winds have diminished and so
too have the waves subsided. The rest of the lake will see
elevated winds through Monday and that portions stays as is
through 10PM.

Southerly offshore winds of 15 to 25 knots will continue
through the evening before turning west by late tonight. The
westerly winds will be enough to produce waves of 3 to 5 feet
through Monday evening. Winds will diminish Monday night as high
pressure approaches and reduce the pressure gradient. Low
pressure develops over the upper Midwest on Tuesday and deepens
to at least 1000mb as it tracks east to southern Ontario by 12Z
Wednesday. This will introduce southerly winds of around 15
knots on Tuesday night. The cold front associated with this
deepening low will track east across the lake bringing with it
strong westerly winds. West to northwest winds with be around 15
to 25 knots in the nearshore zones and up to 30+ knots in the
open waters from Wednesday through Thursday morning. Small Craft
Advisory will likely be needed through this period with gales
possible over the open waters if the low deepens enough. The GFS
the low deepening to as low as 988mb, which may be sufficient
for gales over the lake. Winds slowly diminish after this as the
low moves off to the east on Thursday and Friday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 10 PM EDT Monday for LEZ145>149.

&&

$$
SYNOPSIS...Griffin
NEAR TERM...Griffin/Jaszka
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Jaszka
MARINE...Oudeman/Saunders