Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kcle 231559 
afdcle

Area forecast discussion
National Weather Service Cleveland Ohio
1159 am EDT Mon Sep 23 2019

Synopsis...
a cold front should traverse Northern Ohio and northwest PA from west
to east between about 6 am this morning and 4 PM this afternoon.
High pressure follows this front later today through Wednesday.
Another cold front should move east across our area Thursday
morning. Behind this front, high pressure should impact Northern
Ohio and northwest PA later Thursday into Friday. Yet another
cold front may move east across our region on Saturday.

&&

Near term /through Tuesday/...
updated...no big changes needed for the afternoon update.



Previous...freshened pops through early this afternoon given
changes made by our neighboring offices and to account for
latest observations, including radar data. The cold front is
nearing Toledo Airport and the northwest tip of our County Warning Area at time
of writing and will continue to progress eastward. Still can't
rule out a few thunderstorms embedded within the rain band
accompanying this eastward-moving front. A separate rain band is
in the process of exiting far-eastern portions of the County Warning Area to
the east. As radar imagery shows, cannot rule out additional
rain showers and perhaps a few thunderstorms developing in
between the two aforementioned rain bands. This is due to a warm
conveyor belt undergoing isentropic lift ahead of the
approaching front.

Previous discussion (426 am)...a swath of rain showers is
affecting much of Northern Ohio and Lake Erie as of 4:00 this
morning. These rain showers are likely tied to isentropic lift
of a warm conveyor belt that is translating eastward, ahead of a
shortwave trough and accompanying surface cold front
approaching from the west. This cold front should cross our County Warning Area
from west to east between roughly 6 am this morning and 4 PM
this afternoon as the shortwave begins overspreading the eastern
Great Lakes region. A band of additional rain showers and a few
thunderstorms will likely accompany this front. Despite
moderate to strong vertical wind shear, limited instability will
likely preclude any severe storms. Nevertheless, any
thunderstorm that occurs late this morning through late
afternoon will likely be surface-based as the boundary layer
undergoes some diurnal destabilization. Any surface-based
thunderstorm may produce strong wind gusts as precipitation may
be efficient at transporting stronger winds aloft to the
surface. Breezy southwesterly surface winds shift to westerly
following the passage of the cold front and skies are expected
to undergo at least partial clearing behind the front. Today
will be much cooler than yesterday, with near- normal high
temperatures in the low to mid 70's.

By this evening, the shortwave trough will continue moving eastward
over the eastern Great Lakes region, including our cwa, and will be
followed by high pressure at the surface and aloft building from the
west through Tuesday. Surface winds subside during this period as
the pressure gradient relaxes. Fair weather should affect most of
our forecast area this evening through Tuesday. However, a west-
northwesterly to northwesterly mean boundary layer flow crossing
Lake Erie should be cold enough to trigger multiple bands of
lake-effect rain showers, especially this evening through
Tuesday morning. These rain showers should target northwest PA
and far-northeast Ohio. Low and high temperatures are expected to
be near-normal on Tuesday.

&&

Short term /Tuesday night through Thursday/...
Tuesday night the high shifts east and the return flow allows
for another bump up in temperatures for Wednesday ahead of the
next cold front. This front will be accompanied by a broad, but
shallow trough with the bulk of the forcing remaining north of
the area. Will continue with low precip chances, with the
exception of across the lake into northwest PA Wednesday
night/Thursday morning with the best convergence along the
front. Temperatures will retreat closer to normal for
Thursday/Thursday night with high pressure shifting across the
Ohio Valley.

&&

Long term /Thursday night through Sunday/...
the end of the work week ends up with zonal flow aloft with a
tendency toward a building west trough/East Ridge for the weekend.
There is a large degree of spread on the track on positioning of a
frontal system for the weekend. The GFS is the cooler/colder
solution pushing the cold front through on Friday night and keeping
the entire weekend on the north side of the front with seasonable
temperatures. On the other hand the ensemble mean and the European model (ecmwf) show
the upper ridge building and holding off the front a while longer.
This continues with the continuity we had with forecasting above
normal temperatures for the coming weekend. Will keep with that
until we see enough evidence to change. This uncertainty makes it
hard to pinpoint any day over another for better precip chances just
yet too.

&&

Aviation /12z Monday through Friday/...
mainly VFR expected next 24-hours. A cold front should sweep
east across Northern Ohio and northwest PA between roughly 11z and
20z/Mon. Scattered showers are expected and isolated
thunderstorms are possible along and ahead of this front. The
best potential for isolated thunderstorms with erratic surface
wind gusts up to 40 knots exists east of a kcle to kmfd to kcmh
line between roughly 14z and 20z/Mon. In addition, MVFR to IFR
ceilings and MVFR visibility may accompany precipitation. Non-
VFR ceilings should gradually clear most of the region from
northwest to southeast between late morning and early evening
today.

Breezy southwesterly surface winds ahead of the front will
shift to westerly or west-northwesterly behind the Front. Lake-
effect rain showers may develop behind the cold front after
00z/Tue and affect far-northeast Ohio and northwest PA, including
Keri. MVFR to IFR ceilings are possible in this lake-effect
precipitation.

Outlook...non-VFR possible in lake-effect rain showers
southeast of Lake Erie Tuesday. Non-VFR also possible in
showers with a low chance of thunderstorms Wednesday evening
into Thursday morning.

&&

Marine...
southwest winds have picked up on the lake overnight preceding the
cold front just west of the lake. This front will cross the lake
today and shift winds to the west. The Small Craft Advisory will
stand as is and run through tonight and into Tuesday morning. Speeds
of 15 to 25 knots will be common. By midday Tuesday though the high
across the Ohio Valley will take over and winds/waves will
diminish/subside. Southwest flow increases again Wednesday ahead of
the next cold front to cross Wednesday evening. This may generate
marginal Small Craft Advisory waves Wednesday night into Thursday.
High pressure returns for later Thursday into Friday.

&&

Cle watches/warnings/advisories...
Ohio...beach hazards statement through Tuesday morning for ohz011-012-
089.
Beach hazards statement through late tonight for ohz009-010.
PA...beach hazards statement through Tuesday morning for paz001.
Marine...Small Craft Advisory until 10 am EDT Tuesday for lez146>149.
Small Craft Advisory until 4 am EDT Tuesday for lez142>145.

&&

$$
Synopsis...jaszka
near term...jaszka/tk

National Weather Service Glossary of Abbreviations