Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 170312
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
1012 PM EST Thu Nov 16 2017

.SYNOPSIS...
A trough will finish crossing the eastern Great Lakes this
evening. High pressure will build overhead for later tonight and
Friday. A warm front will lift north early Saturday morning with
the low center tracking across northern Indiana and across Lake
Erie during the day. A strong cold front will follow Saturday
evening. High pressure will build across the lower Ohio Valley
late Sunday and across the upper Ohio Valley Monday.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
Update...Previous forecast remains on track. Only made minor
adjustments to the hourly temperature grids.

Original Discussion...
Trend for this evening will be for the scattered light
showers/drizzle across north-central OH east to nw PA to
diminish and come to an end closer to midnight. This is as a
trough across the eastern lakes exits taking with it the deeper
moisture and the ridge begins to build in from the west. Up to
this point only a few wet flakes have mixed in with the rain.
This will continue to be possible this evening, but any
accumulation would be hard to come by. Others will keep the
cloudy skies with breaks limited. Feel the stratus will be hard
to get rid of tonight and most will likely have to wait until
tomorrow and a south flow to scour it out. Temperatures today
have been holding in the upper 30s/lower 40s. Only expecting a
drop to just below freezing tonight which is slightly warmer
than guidance due to the cloud cover forecast.

Quiet weather day Friday with high clouds expanding and
thickening. Highs in the 40s. Southerly flow increases Friday
night. Rain will rapidly expand across the area with a
significant amount of moisture transport and arrival of upper
support. Lows will be early in the evening with the rising
temperatures going into Saturday morning. Kept the mention of
thunderstorms with some elevated instability.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A fairly compact upper level trough moving east across the CONUS
will become negatively tilted over the Great Lakes Region by
Saturday evening. Low pressure tracking out of the Plains will
deepen as it moves northeast to near Lake Erie by 00Z Sunday, then
rapidly deepens overnight as it continues northeast into Sunday. A
strong 55-65 knot low level jet will move overhead on Saturday, with
a warm front lifting north across the area. Widespread rain is
expected on Saturday with the front and will continue with a chance
of thunderstorms with some elevated instability. A strong inversion
will prevent the stronger winds aloft from mixing down although
breezy conditions are expected. Locally stronger winds are possible
at Erie, PA where downsloping may result in wind gusts to 40
mph or higher. The temperature forecast is difficult on Saturday
with warm advection offset by rain. Kept highs in the upper 50s
but could be warmer in some sites, especially if sizable breaks
in the rain occur in the south. Convection is not expected to
become surface based but that is something to watch.

A strong cold front sweeps east across the area Saturday evening
with temperatures falling quickly behind the front. Gusty winds of
30 to locally 40 mph are expected along the front. Precipitation
will linger in the east overnight as the low continues to deepen
while tracking towards Quebec. Rain will transition to snow although
accumulations will be limited by warmer flow off the lake and
the wet ground. The forecast includes around an inch of
accumulation over the higher areas in northwest PA. Will
continue to evaluate timing of the rain to snow transition and
adjust forecast as needed.

Precipitation transitions to lake effect on Sunday as 850mb temps of
-10C move across Lake Erie. Despite good low level instability, we
 lack upper level support with drier air spreading in from the
 west during the day. There may be upstream contribution from
 Lake Huron but that is expected to shift east. Enough limiting
 factors to keep accumulations on the low side and generally
 focused over the higher terrain in PA. Could see an inch or 2
 across inland portions of the Ohio snowbelt with a few inches
 in NW PA. As the flow backs on Sunday night, will need to watch
 for some intensification of a westerly band off Lake Erie but
 confidence is low at this point. Snow showers will become
 confined closer to the lake on Monday before coming to an end.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
High pressure will be sliding off the east coast of the US Monday
night with warm advection occurring across the County Warning Area.
The next cold front will arrive Tuesday afternoon but it appears we
will be dry. However lake effect snow will likely develop in the
wake of the front Tuesday night into Wednesday. There is uncertainty
how long this will linger into Thursday with models differing on how
fast high pressure ends the snow.

Tuesday will be the warm day of the long term with highs in the
middle to upper 40s. Temperatures will drop to below seasonal
averages Wednesday into Thursday with highs 35 to 40 degrees.

&&

.AVIATION /00Z Friday THROUGH Tuesday/...
Will still have a few showers off of the lake for CLE/YNG and
points east for the remainder of the evening. There could be a
few wet snowflakes mixed in, mainly at KYNG. West-northwest
winds will continue to gust to 25 knots at KERI for a couple
more hours before subsiding this evening. Winds have already
subsided elsewhere. Overcast MVFR ceilings will continue to be
widespread. Many sites will continue to flirt with low VFR
ceilings through around 06Z or so, but MVFR conditions should
settle back in thereafter the remainder of the night at most
locations. High pressure moves overhead tonight and winds will
go light/variable and then establish a south flow for Friday.
After low clouds break tomorrow afternoon, expect just the
overspreading of high clouds from the approach of the weekend
system.

OUTLOOK...Non-VFR returns late Friday night and persists
through sunday morning. Northeast OH/nw PA likely to keep non-
VFR into Monday morning. Thunderstorms possible late Friday
night and Saturday. Rain changes to snow Saturday night. Lake
effect snow showers develops in the snowbelt Sunday into Monday.

&&

.MARINE...
Winds are starting to decrease on Lake Erie as low pressure over
Quebec departs to the northeast. A Small Craft Advisory will remain
in effect on the western basin through 10 PM with eastern areas
expiring at 4 AM. Winds will drop off quickly late tonight as high
pressure over the western Great Lakes expands eastward.

Southerly winds will develop as the high shifts to the east Friday.
Winds will increase Friday night into Saturday with Small Craft
conditions and winds of 20-25 knots ahead of an approaching low
pressure system. Low pressure tracking out of the Mississippi Valley
will undergo rapid deepening into Saturday night as it tracks
northeast into Canada, pulling a strong cold front east across Lake
Erie. Gale force winds can be expected with a wind shift to the
northwest behind the cold front Saturday night with Small Craft
conditions lingering Sunday into Sunday night. We will have to
monitor water levels on the western basin of Lake Erie ahead of the
front on Saturday. Water levels are forecast to drop to near the
critical mark for safe navigation.

High pressure will build east across the Tennessee Valley on
Monday with winds backing to southwest. Brisk winds expected to
continue and Small Crafts may need to be extended.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 4 AM EST Friday for LEZ145>149.

&&

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



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