Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 211425
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
1025 AM EDT Fri Sep 21 2018

.SYNOPSIS...
A strong cold front over the western Great Lakes early this
morning will race eastward crossing the region this afternoon
into the early evening. A much cooler are of high pressure will
settle over the area for the weekend. A warm front will lift
across northward across Ohio and northwest Pennsylvania Late
Monday into Tuesday.

&&

.NEAR TERM /THROUGH SATURDAY/...
A broken line of showers extends from west of Indianapolis to
Central Lower Michigan as of 10 AM. Lightning has been isolated
along this line and making fairly slow progress eastward this
morning. This band of showers is expected to approach the I-75
corridor in NW Ohio between 16-17Z. This line of activity will
intensify this afternoon as it moves into the more unstable
airmass across northern Ohio this afternoon, also getting a
boost from the 700mb jet lifting NE across the Central Great
Lakes.

Main changes to the forecast this morning were to slow storms
down by an hour or two across much of the area, and also lower
dewpoints given considerable mixing with the breezy conditions
ahead of the front. Despite this, moisture pooling along the
front should still allow for sufficient destabilization for the
line of storms to fill in as it reaches NE Ohio. The Storm
Predication Center has expanded the tornado threat westward to
include much of NE Ohio with the main concern being any discrete
cells earlier on in the event before we transition to more of
a linear structure. Shear will be more than sufficient for
damaging wind gusts which will be the primary severe weather
concern this evening between 4 and 8 PM.

Previous Discussion...
Active weather expected today, so have a plan to protect
yourself from severe weather this afternoon and evening.

There is a slight risk of severe thunderstorms this afternoon as a
strong cold front moves into northwest Ohio. Thunderstorms are
expected to develop along the front and move quickly eastward.
The main threat will be strong damaging winds.

There is also an enhanced risk of severe thunderstorms across
Northeast Ohio into Northwest Pennsylvania this afternoon into
early evening. Thunderstorms that develop along a cold front as
it moves into northwest Ohio early in the afternoon will reach
northeast Ohio into NW PA by late afternoon. The threat of
strong damaging winds will increase as storms move into this
more unstable airmass. Also of concern is the development of
thunderstorms ahead of the front along a lake induced boundary
that will be located from eastern Cuyahoga county northeastward
into northwest Pennsylvania. These thunderstorms have a greater
potential of being isolated supercells which could produce
strong damaging winds, large hail or a tornado.

Gusty southwesterly winds may also become an issue ahead of the
cold front. At this point in time we will not issue a wind
advisory but it may get close west of I-71. So for now we will
cap the gusts at 40 mph. Winds shift to the northwest by late
evening at most locations with some cooler drier air arriving.
The cooler air flowing over the warm waters of Lake Erie will
likely cause some light showers later Friday night into at least
midday on Saturday. Most of these will occur in the higher
terrain from the Mid Ohio region northeastward into NW PA.

Today will be the last hot day with most locations well into
the 80s. A few 90s will also be possible where the cloud cover
develops the slowest this morning. Cooler tonight with 50s
common. If winds decrease enough across NW Ohio a few upper 40s
will be possible. IT will feel much cooler on Saturday with
highs only in the lower/mid 60s.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
Fall begins at 9:54pm ET on Saturday night and the weather will
quickly reflect the change in the astronomical season. High pressure
will continue to building into the area Saturday night into Sunday,
keeping the area fairly dry with dew points in the upper 40s to
lower 50s. Temperatures will be continue to be cool as cold,
Canadian air moves into the area. Lows on Saturday night could be
quite chilly into the upper 40s in several locations. Temperatures
on Sunday will rebound a bit as 850mb flow begins shifting back
around to the south to bring some warner air into the area.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The long term forecast period looks active and wet for the first
half of next week. High pressure begins departing the region on
Monday as an upper trough moves toward the region early next week,
supporting a low pressure system at the surface. The extended
guidance has much improved agreement on a warm front lifting across
the area on Monday night followed by a cold front crossing the area
on late Tuesday into Wednesday. Have trended pops higher through the
period with likely pops on Tuesday and Tuesday night with the cold
frontal approach and passage. High pressure will build in behind the
cold front for Thursday with another cool and dry Canadian high
pressure. Temperatures will generally be near normal to start,
although they will trend to below normal by the end of the period.

&&

.AVIATION /12Z Friday THROUGH Tuesday/...
VFR conditions anticipated through the morning. We will then
monitor for the development of thunderstorms along and ahead of
a cold front that will sweep across the region through the
afternoon/early evening. Will also have to watch a lake induced
boundary across NE OH and NW PA. This convergence may induce the
development of thunderstorms well ahead of the cold front. In
any event the thunderstorms will become strong to severe with
strong damaging winds the main concern. Will place a 2 to 3
hour tempo window in the TAF`s when they are most likely to
occur.

Southerly winds will become southwesterly ahead of the
cold front today. Wind speeds around 20 knots will be common
with gusts away from thunderstorms still reaching 30+ knots.
The strongest gusts will likely be west of I-71. Winds shift to
the west and northwest Friday evening through 06z. Speeds will
gradually decrease to around 10 knots, stronger near the
lakeshore.

OUTLOOK...Non-VFR fog possible Sunday morning. Non-VFR showers
possible Monday into Tuesday.

&&

.MARINE...
A rough couple of days ahead on Lake Erie as a low pressure system
moves through the Great Lakes region. A small craft advisory has
already been hoisted for the nearshore waters of the lake as winds
will increase ahead of a cold front today and then quickly shift to
onshore flow with the frontal passage. Waves will increase to 4 to 7
feet later today into tonight as winds reach as high as 30 knots
with higher gusts possible. Have also put up a beach hazards
statement for the lakeshore counties as wave action will be
hazardous for swimming.

High pressure will build into the region for the weekend and winds
should become light from the north to northeast for Saturday. There
could be some residual chop over Lake Erie on Saturday as waves will
subside Saturday morning, so perhaps not the best marine day to
start. Winds will become light and variable by Sunday, so Sunday and
Monday shouldn`t be too bad of days on the lake. High pressure
departs the area on Monday and the next low pressure system
approaches on Monday night for early next week. A warm front will
cross the lake Monday night and a cold front will approach the lake
on Tuesday, crossing the lake Tuesday night into Wednesday.
Conditions on the lake will deteriorate mid-week, something to watch
for now.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement through late tonight for OHZ003-007-
     009>012-089.
PA...Beach Hazards Statement through late tonight for PAZ001.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for LEZ142>149.

&&

$$
SYNOPSIS...Mullen
NEAR TERM...KEC/Mullen
SHORT TERM...Sefcovic
LONG TERM...Sefcovic
AVIATION...Mullen
MARINE...Sefcovic


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