Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Cleveland Ohio
133 PM EST Tue Nov 12 2019
low pressure will track northeast reaching the New England
states later this morning. Arctic high pressure will then build
into region from the southwest tonight. This high will quickly
shift to the East Coast of the US by wedneday evening. This will
allow a clipper storm system to dive across the central Great
Lakes region on Thursday. Temperatures will be slightly below
average for the end of the week and weekend.
Near term /through Wednesday/...
Our Lake effect snow-related headlines remain unchanged. Please
see our Winter Storm Warning and Winter Weather Advisory
statements for further details. The lake snows are still
expected to gradually pivot east and north through early
Wednesday afternoon as the low-level flow of cold air backs from
northwesterly to westerly to west-southwesterly and allows the
snow to eventually retreat over Lake Erie. The lake effect snow
will weaken gradually, especially this evening into Wednesday as
a lowering and strengthening subsidence inversion accompanying
a building high pressure ridge allows lake-induced cape to wane.
The rest of our near-term forecast remains valid. See below
discussions for further details.
1028 am discussion...the Winter Weather Advisory was allowed to
expire at 10 am this morning for Erie, Huron, Ashland, and
Wayne counties in Ohio. Here, the lingering lake effect snow is
expected to mainly be light and should exit the area to the east
by early afternoon. Farther east, the Winter Weather Advisory
and Winter Storm Warning for lake effect snow remain valid. In
addition, added Mahoning County to the Winter Weather Advisory,
which is in effect until 7 PM this evening. Nam12 pop and quantitative precipitation forecast
guidance has been performing fairly well lately given observed
trends over the past couple hours. Thus, we may need to adjust
pops, qpf, and snowfall downward for our PA counties through
this afternoon due to the potential for significant low-level
shear to limit lake-induced instability. Will continue to
evaluate for the early afternoon update. A northwesterly low-
level flow is expected to continue triggering multiple lake
effect snow bands off Lake Erie with the potential for one or
two stronger snow bands tied to an upstream connection to Lake
Huron. This northwesterly flow of cold air will gradually back
to westerly and then west-southwesterly during Wednesday morning
and early afternoon, allowing the lake effect snow to pivot
northeastward and eventually retreat over Lake Erie.
Additional snow accumulations are expected to be highly
variable. These should average 1 to 3 inches in the advisory. In
the Ohio snowbelt portion of the Winter Storm Warning, 2 to 4
inches of new snow are expected, with localized amounts up to 7
inches possible where heavier bands persist the longest. This
may especially be the case in the higher terrain of Geauga
County. In the PA snowbelt, additional snowfall is forecast to
average 3 to 9 inches, with the greatest amounts in the higher
terrain of southern Erie and northern Crawford counties. The
rest of our near-term forecast remains valid.
627 am discussion...the synoptic snow system has moved out of
our area and we have transitioned into lake effect snow across
the primary and secondary snowbelt areas this morning. The main
upper level trough will move across the Great Lakes later today.
850 mb temperatures are still cooling and will eventually
bottom out around -15c over the area. Due to the nature of the
north-northwest to northwest flow with the first 10k above the surface, we can
expected multiple bands of lake effect to develop and impact
northeast Ohio and northwest Pennsylvania today into tonight.
The flow will become a little more westerly but lighter tonight.
This change should take the lake effect bands more into
northwest Pennsylvania tonight and eventually diminish by
Wednesday morning. We will continue the warning for the primary
snowbelt areas and the advisory as is for the secondary
snowbelt. Additional snowfall is expected with the heaviest
amounts where bands are able to persist across portions of
Geauga County and northeastward towards Erie County PA.
Tonight, skies will clear out for areas away from the lake and
lake induced clouds and snow. With fresh snowfall and an Arctic
high moving across the Ohio River valley tonight with lighter
winds, record low temperatures are likely areawide. There will
even be some single digit numbers where the winds are lightest
and skies clear out across western and central Ohio tonight and
Wednesday morning. See climate section below the current record
The lake effect snow machine will cut off for our snowbelt areas
by Wednesday morning and a light southerly wind will return on
the back side of the Arctic high. Temperatures will still
struggle to reach above freezing again on Wednesday. Sunshine
will not be able to help because high and mid level cloudiness
will increase during the day from west to east ahead of the next
Short term /Wednesday night through Friday night/...
another shortwave trough will swing east across the forecast area
and precede a larger broad trough that will affect the eastern
United States during this period. Surface high pressure will build
east across the area and then move off the East Coast Thursday. A
surface trough as a reflection of the upper level trough will move
east across the area Thursday night followed by a cold front Friday.
Some residual lake effect will take place over the lake and possibly
along the immediate Lakeshore Wednesday night into Thursday.
Temperatures should warm enough to support mainly rain by Thursday
afternoon. As cold front shifts south across the area, colder air
will return and send flow back to northwest resulting in a
possibility for some More Lake effect Friday. Otherwise, generally
fair weather will dominate the rest of the forecast area through
this period under the influence of the high pressure. Surface trough
is expected to swing through the area dry along with the cold front
Friday. Lake snow could extend further inland over the northeast
portions of the forecast area by Friday night. Temperatures will be
moderating slightly through this period.
Long term /Saturday through Tuesday/...
somewhat broad upper level ridge will move east over the region
Saturday into Sunday. Another broad upper level trough will move
east toward the area Monday. Otherwise, surface high pressure will
be the dominant weather feature across the area after the passage of
a cold front Friday. The high will build east across the central
Great Lakes Friday night and off the coast of Maine Sunday. A ridge
will extend back west over the Great Lakes into Monday. So, no real
threats of precipitation expected during this forecast period.
Further warming of temperatures is expected through the forecast
period as cold air retreats to the east and a return southerly flow
takes place on the back side of the high pressure.
Aviation /18z Tuesday through Sunday/...
localized MVFR to LIFR continue today into Wednesday morning in
multiple lake effect snow bands across the snowbelt of
northeast Ohio and northwest PA, including kcak, kyng, and Keri.
Outside of these snow bands, VFR to MVFR today should transition
to primarily VFR Wednesday. Northwesterly surface winds of 10
to 15 knots, gusting up to 25 knots, ease by early this
evening. Thereafter, primarily light and variable winds are
expected during the rest of the taf period as high pressure
continues building into the area.
Outlook...periods of non-VFR possible in scattered snow and/or
rain showers Wednesday afternoon through Friday.
low pressure will continue to move northeast of the area today and
gradient across the area will keep winds strong enough to support
Small Craft Advisory conditions through tonight. Flow shifts around
to a southerly direction Wednesday ending the Small Craft Advisory
threat. Flow gradually becomes westerly by Thursday night and then
northwest Friday as a cold front moves southeast across the lake.
Will likely need another Small Craft Advisory again Friday into
Saturday as winds shift around to the east by Saturday
Arctic air will move southeast into the local area today and
then begin to shift east tonight. The unseasonably cold air
will cause temperatures to plummet to some of the coldest
readings so far this season.
Below are the coldest temperatures on record for selected dates
at our six climate sites:
Tuesday, November 12:
Coldest high (year) coldest low (year)
Akron-Canton area: 28 (1920) 16 (1950)
Cleveland area: 31 (1920)18 (1911)
Erie area:34 (1996)18 (1911)
Mansfield area:29 (1996)16 (1976)
Toledo area:30 (1995)15 (1976)
Youngstown area: 30 (1996)19 (1950)
Wednesday, November 13:
Coldest high (year) coldest low (year)
Akron-Canton area:25 (1911)12 (1911)
Cleveland area: 22 (1911) 15 (1911)
Erie area: 23 (1911)16 (1911)
Mansfield area:27 (1986)13 (1986)
Toledo area:22 (1986)13 (1911)
Youngstown area:29 (1996)17 (1986)
Ohio...Winter Storm Warning until 10 am EST Wednesday for ohz011>014-
Winter Weather Advisory until 7 PM EST this evening for ohz010-
PA...Winter Storm Warning until 1 PM EST Wednesday for paz001>003.
Marine...Small Craft Advisory until 4 am EST Wednesday for lez144>149.
Small Craft Advisory until 11 PM EST this evening for lez142-