183
FXUS61 KCLE 011741
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
141 PM EDT Tue Oct 1 2024

.SYNOPSIS...
A very weak trough lingers over our region as a cold front
approaches from the western Great Lakes. This cold front is
poised to sweep eastward through our area late this afternoon
through the wee hours of Wednesday morning. Behind the front, a
ridge builds from the Upper Midwest and vicinity through Wednesday
and then begins to exit toward the Northeast and Mid-Atlantic
states on Thursday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
100 PM...
Recent satellite imagery depicts a well-defined cold front
draped roughly northeast to southwest across central MI this
afternoon. Precipitation coverage will increase later this
afternoon and evening from west to east across the area along
and just ahead of the front. A few embedded thunderstorms are
possible, though the probability is low. Abrupt wind shifts
towards the north and northwest can be expected with the cold
front later this evening, with brief gusts of 25 to 30 mph
possible.

Previous Discussion...
Breaks in low clouds, very weak or calm surface winds, and
abundant low-level moisture have permitted the development of
patchy and dense radiation fog between Toledo, Lorain, and
Mansfield, including the Fremont area, this morning. Cloud
breaks should contribute to the development of additional and
localized radiation fog through daybreak this morning,
especially west of roughly I-71. The localized nature of this
fog precludes the need for a Dense Fog Advisory. Will continue
to monitor trends in satellite imagery and surface obs closely.
Any fog is expected to dissipate via diurnal convective mixing
of the boundary layer late this morning.

Aloft, a trough associated with the remnants of Helene exits
E`ward from far-NE OH and NW PA this morning. Any sprinkles
accompanying the trough are expected to exit the same areas by
daybreak. Otherwise a weak shortwave ridge traverses our CWA
from west to east through this early evening as a potent
shortwave trough approaches from the Upper Midwest and vicinity.
This shortwave trough is still expected to traverse the Lake
Erie region and Upper OH Valley from west to east tonight. At
the surface, a weak trough lingers over northern OH and NW PA as
a cold front approaches from the western Great Lakes. This cold
front is expected to sweep E`ward through our CWA late this
afternoon through the wee hours of Wednesday morning. Behind the
front, a ridge builds from the Upper Midwest and vicinity.

Odds favor fair weather through midday today. Thereafter, moist
isentropic ascent aloft, preceding the aforementioned shortwave
trough`s axis, and low-level convergence/moist ascent along the
cold front will trigger scattered rain showers. Net low-level
WAA and daytime heating amidst peaks of sunshine are expected to
allow highs to reach the upper 60`s to mid 70`s in NW PA and
mainly the 70`s in northern OH late this afternoon, prior to the
cold front passage. Diurnal convective mixing of the warm/moist
sector boundary layer is expected to yield weak MUCAPE, steep
low-level lapse rates, and DCAPE near 500 J/kg amidst moderate
effective bulk shear this afternoon through early evening. As a
result, low-level convergence/moist ascent along the cold front
should trigger isolated thunderstorms capable of producing
convective wind gusts up to 50 mph, especially in northern OH.
Behind the cold front, a NW`erly to N`erly mean low-level flow
associated with strong low-level CAA and 850 mb temperatures
dropping to near 7C over ~22C Lake Erie will allow a very brief
period of lake-effect rain showers to occur over and generally
south-southeast of the lake. These lake-effect rain showers are
still expected to end by daybreak Wednesday morning as lake-
induced CAPE wanes quickly via a lowering subsidence inversion
and significant low-level dry air advection accompanying the
aforementioned ridge. Lows are still expected to reach mainly
the upper 40`s to mid 50`s around daybreak Wednesday.

Fair weather is expected during the day on Wednesday as the
ridge at the surface and aloft continues to build from the Upper
Midwest and vicinity, and is accompanied by stabilizing
subsidence. Late afternoon highs are still expected to reach the
60`s to near 70F as daytime heating is limited by net low-level
CAA.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
We start the short term period with an upper-level ridge over the
southeast CONUS, extending northward into the Ohio Valley. At the
surface, A 1018mb high will be centered over the area Wednesday
night. Both of these features gradually move eastward on Thursday
and Thursday night, with clear/sunny skies expected Wednesday night
through Thursday night, other than some cirrus Thursday afternoon
and Thursday night. An upper-level trough moves across the Great
Lakes region Friday and Friday night, with fairly limited moisture
expected to accompany this trough. The ensemble mean and "most
likely scenario" is for there to be no precipitation accompanying
this trough except for some isolated rain showers in Northwest
Pennsylvania Friday night because the best forcing is expected to be
to the north and there will be limited moisture. However, there is a
small percentage of ensembles that has scattered light rain showers
Friday afternoon. For now, will not include a mention of
precipitation. Temperatures in the short term period will run a few
degrees above normal with highs in the mid 70s and lows in the low
50s.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
An upper-level ridge and surface high pressure briefly build on
Saturday with sunny skies expected, though temperatures a couple
degrees cooler thanks to the cold front Friday and Friday night.
Temperatures warm back up to the mid 70s on Sunday on the backside
of the departing high pressure pressure. Most model guidance is
trending towards a more potent trough moving across the Great Lakes
region Sunday afternoon into Sunday night, so have increased PoPs to
at least 30% areawide Sunday afternoon/evening and to 40-60% for
Sunday night. This is a decent change compared to the previous few
cycles of model guidance so only gradually increasing the
probabilities with this forecast update but could see these
probabilities increasing if there is more run-to-run consistency.
Also included a slight chance of thunderstorms as most models have
good moisture return in response to the approaching trough,
contributing to some instability. The associated cold front moves
across the area Sunday night with most model guidance having a
relatively cold airmass flowing in behind it. Have starting trending
temperatures towards below normal on Monday with a chance for lake
effect rain showers.

&&

.AVIATION /18Z Tuesday THROUGH Sunday/...
Mixed-bag of MVFR and VFR ceilings across the TAF sites this
afternoon. Non-VFR conditions are anticipated to arrive along
and behind a west-to-east-moving cold front later this evening
and overnight. IFR ceilings are possible at MFD/CLE/CAK/YNG/ERI
behind the cold front. Brief IFR vsbys in a line of rain showers
along the front are also possible at CLE/ERI this evening.
Conditions should improve to VFR areawide by Wednesday morning.

Winds are generally light and variable this afternoon across the
TAF sites, less than 5 knots. Winds will abruptly shift towards
the north and northwest behind a cold front this evening and
overnight, increasing to 10 to 15 knots with a brief period of gusts
of 20 to 25 knots possible. Winds will generally remain out of
the north to northwest overnight, though decrease slightly in
the 5 to 10 knots range.

Outlook...Non-VFR conditions are possible in scattered rain
showers on Sunday.

&&

.MARINE...
Relatively quiet conditions are expected today on Lake Erie before a
cold front moves east across the area this evening into tonight.
Strong winds are expected to develop behind this cold front with a
rapid and sudden change in the wind speed and direction, with
conditions changing from light winds out of the south around 5 knots
to 20-30 knots out of the northwest and north with the frontal
passage. This sudden increase in wind speed is expected to occur as
early as 21Z on the western basin, after 23Z east of The Islands,
and around 03Z near Erie, PA. The strong winds of 25-30 knots are
only expected to last for a few hours this evening and tonight
before they gradually dissipate to less than 15 knots by 14Z and
less than 10 knots by 18Z. Peak significant wave heights of 5-8 ft
will be possible in the central basin tonight. A small craft
advisory will be in effect for the southern nearshore zones of Lake
Erie for this reason. High pressure builds in Wednesday and
Wednesday night, with quiet conditions ensuing. South to southwest
winds develop Wednesday night through Thursday night as the high
departs to the east. A weak cold front moves across the area Friday
into Friday night with northwest winds Friday afternoon becoming
northeast by Friday night and Saturday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 4 AM EDT Wednesday for LEZ142-143.
     Small Craft Advisory from 7 PM this evening to 10 AM EDT
     Wednesday for LEZ144>148.
     Small Craft Advisory from 10 PM this evening to 10 AM EDT
     Wednesday for LEZ149.

&&

$$

SYNOPSIS...Jaszka
NEAR TERM...Jaszka/Kahn
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Kahn
MARINE...Saunders