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442
FXUS61 KCLE 200139
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
939 PM EDT Mon May 19 2025

.SYNOPSIS...
A ridge extends from the Hudson Bay area to northern Ohio and
northwest Pennsylvania. This ridge exits gradually eastward from our
region through Tuesday as a trough approaches and eventually
overspreads our region from the northern and central Great Plains.
Simultaneously, the trough`s embedded low wobbles eastward from the
Nebraska/Kansas border area toward the Mid Mississippi Valley. The
trough lingers in our area Tuesday night through Wednesday as the
low wobbles farther eastward toward Mid Ohio and then the Upper Ohio
Valley.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
-- Changed Discussion --
9:30 PM Update...

The winds are dropping off as anticipated post sunset, and with
IR satellite loops showing skies clearing, the Frost Advisory
looks to be on track for NW PA. Current temperatures in the
upper 40s to mid 50s will cool rather quickly as winds continue
to decouple.

6:30 PM Update...

The forecast remains on track for this evening with no changes
needed.

Original Discussion...

Fair weather is expected to persist through daybreak Tuesday as
stabilizing subsidence accompanies a ridge. Aloft, the ridge
axis drifts E`ward from western Lake Superior and the Lower OH
Valley toward eastern Lake Superior, western Lake Erie, and the
Upper OH Valley. At the surface, the ridge continues to impact
the Lake Erie region and Upper OH Valley, including our CWA, as
this portion of the ridge exits E`ward very slowly. Moist
isentropic ascent ahead of a trough axis aloft approaching from
the Intermountain West and Great Plains will allow cloud cover,
mainly in the mid/upper-levels, to continue to overspread our
region generally from west to east and increase gradually.
Greater cloud cover toward the west in our CWA will contribute
to overnight lows reaching the upper 30`s to mid 40`s in NE OH
and the mid 40`s to lower 50`s farther west. In NW PA, easing
surface winds and clearer sky should enable lows to reach the
mid 30`s to mid 40`s, with the coldest lows expected inland from
~60F Lake Erie. Areas of frost formation are expected during
the predawn hours of Tuesday morning in southeastern Erie County
and eastern Crawford County, PA. A Frost Advisory remains in
effect for southern Erie County and Crawford County from 2 AM to
8 AM EDT Wednesday.

On Tuesday through Tuesday night, the ridge axis aloft should linger
over eastern Lake Superior as the same ridge axis, farther south,
drifts farther E`ward toward Georgian Bay and the Mid-Atlantic
region. The aforementioned trough axis aloft should drift E`ward
from the northern and central Great Plains toward the Upper and Mid
MS Valley as a separate trough axis aloft lingers near southeastern
Hudson Bay and the western border of QC. At the surface, the
aforementioned ridge exits E`ward to New England as a trough
overspreads our region from the west and the embedded low moves from
the IA area to the Mid OH area. The expected weather pattern
evolution at the surface and aloft will keep our CWA in the cold
sector and an unusually-cold air mass for this time of year.
Tuesday`s daytime highs should reach the upper 50`s to mid 60`s.
Overnight lows should reach the upper 40`s to mid 50`s around
daybreak Wednesday.

The aforementioned low pressure system`s bifurcating warm conveyor
belt will tap into abundant moisture from the Gulf, undergo
isentropic ascent, and be associated with a frontogenetical
deformation zone. Periods of rain, steady to heavy at times and
associated with the warm conveyor belt, will overspread our region
gradually from southwest to northeast shortly after daybreak Tuesday
morning through daybreak Wednesday morning. Mainly NE`erly to E`erly
surface winds, associated with cold/dry air advection, will be
accompanied by a dry antecedent low-level atmospheric column.
Therefore, it will take some time for rain to reach the surface via
the wet-bulb effect in a southwest to northeast manner. The moist
isentropic ascent may release weak, yet sufficient and solely
elevated CAPE to generate a few thunderstorms Tuesday evening
through the first few predawn hours of Wednesday morning.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
An upper-level shortwave trough moves across the area on Wednesday
and Wednesday night, with an upper-level low moving in from the
north and filling in over the Great Lakes region through and
Thursday night. This will generally result in cloudy and showery
conditions through the short term period with temperatures in the
50s and 60s (daytime temperatures will be below normal, especially
Thursday). Just about everybody should receive at least a 0.5" of
rain, with many areas probably receiving 1-1.5" of rain (and locally
higher due to convection). There could be some minor flooding but
overall the most common impact will be with wet roads and muddy
yards.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The upper-level low remains overhead on Friday before gradually
departing to the east. As a result, it`s likely the cool, showery
weather continues into Friday. A couple more shortwave troughs may
move southeast across the Great Lakes region over the weekend, with
isolated daytime showers possible, but overall PoPs will be much
lower over the weekend with slight increase to temperatures as highs
climb into the low to mid 60s on Saturday and mid to upper 60s on
Sunday. High pressure should build in on either Sunday or Monday (or
both, depending on model guidance) but either way, there should be a
period of low precipitation chances with temperatures in the upper
60s to maybe 70 on Monday.

&&

.AVIATION /00Z Tuesday THROUGH Saturday/...
VFR will prevail through the TAF period as high pressure
gradually exits the Great Lakes region. A scattered mid-level
deck this evening will quickly clear out by sunset. Low pressure
approaching from the Midwest Tuesday will cause clouds to
gradually increase again, and showers will gradually spread east
and northeastward into the region, but kept cigs VFR through the
end of the TAF period. The rain likely will not reach KCAK,
KYNG, and KERI until after the TAF period late Tuesday evening.

Winds will turn more NE and decrease to 5-10 knots tonight then
increase to 10-15 knots Tuesday.

Outlook...Non-VFR expected with periodic rain showers and
isolated thunderstorms later Tuesday night through Saturday.

&&

.MARINE...
A ridge of high pressure overhead will gradually shift eastward
through tonight as low pressure over the central Great Plains
approaches from the west. This should result in east to northeast
flow gradually increasing in strength tonight through the day
Tuesday, with the western basin first reaching 20 knots late tonight
and then elsewhere at or close to 20 knots Tuesday and Tuesday
night. Winds on the south shore may generally tend to weaken on
Wednesday as low pressure moves eastward along the Lake Erie
shoreline, with moves around 15 knots or so becoming north and
northwest Wednesday afternoon into Wednesday night. For now,
confidence for a small craft advisory is highest in the western
basin where model guidance has a near 100% probability of 20 knots
or greater wind speeds, so started with a small craft advisory
there. Elsewhere, there is a little uncertainty on the eastern
extent, as well as the end time of a small craft advisory elsewhere,
so held off on other areas of Lake Erie for now.

Generally northwest flow continues through the week and into the
weekend. It seems there could be additional periods of small craft
advisory conditions (>20 kt winds and 3-5 ft waves) at various times
Thursday through Friday night.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...Frost Advisory from 2 AM to 8 AM EDT Tuesday for PAZ002-003.
MARINE...Small Craft Advisory from 1 AM Tuesday to 10 PM EDT Wednesday
     for LEZ142>144.

&&

$$

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