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000
FXUS61 KCLE 190138
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
938 PM EDT Thu Apr 18 2024

.SYNOPSIS...
A cold front will cross the region late tonight and Friday
morning. High pressure will return Friday afternoon. A secondary
cold front will move through early Saturday followed by high
pressure returning for the rest of the weekend.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
930 PM Update...
Slight adjustments were made to the temperatures as radiational
cooling as allowed them to be a bit chillier than previously
forecast. The remainder of the forecast remains unchanged.

630 PM Update...
Primary change with this update was slight adjustments to the
onset of precipitation tonight. Scattered showers will still
approach from the west around midnight, but the more organized
band of showers will be a bit later, around 2AM and then will
push east. There remains a chance of thunder in the forecast,
especially west of I71, but with such limited instability and a
diurnally unfavorable environment still not expecting it to be
widespread. SPC maintains the Marginal Risk of severe weather
over the southwestern counties. The primary threat will be gusty
winds. No other changes were needed with this update.

Original Discussion...
Mid/upper shortwave ridging has built into the region this
afternoon, with surface high pressure centered over the southern
Great Lakes. The associated drier air has finally eroded most of the
cloud cover, allowing temperatures to warm into the mid/upper 60s in
NW and north central Ohio. Mid-level clouds held on longer in far NE
Ohio and NW PA, and this combined with a lake breeze has kept
temperatures in the upper 50s there. Expect the clearing to continue
to progress east over the next couple of hours, and NW PA will
finally see sunshine by 20 or 21Z setting up a fairly pleasant
evening areawide.

Unfortunately, the nicer weather will not last long with visible
satellite and water vapor loops showing a broad mid/upper trough
pressing into the northern Rockies, northern Plains, and Upper
Midwest. This trough will slowly expand into the Great Lakes late
tonight and Friday bringing a push of unseasonably cool air into the
region. A strong 125-130 knot H3 jet streak over the Upper Midwest
rounding the base of the trough will support a weak surface low
lifting from the Mid Mississippi Valley this evening to Lake Erie by
Friday morning, extending a cold front through the region. The cold
front is expected to be located roughly along the I-71 corridor at
12Z Friday, with it reaching the OH/PA lines by 15 or 16Z. Showers
will spread into the region from west to east ahead of the front
tonight, beginning after 04Z in NW Ohio and reaching the I-71 and I-
77 corridors by 09-11Z. It will take until 12Z or so for the showers
to reach far eastern Ohio and western PA. These showers will be
driven by a 30-35 knot low-level jet in response to the
aforementioned jet streak, leading to weak warm/moist advection and
isentropic ascent combined with strong low-level convergence ahead
of the cold front. As the surface low approaches from the southwest
tonight, a warm front should at least arc into western and central
Ohio leading to backed low-level flow and low-level SRH increasing
over 200 m2/s2 along the boundary. Guidance has trended a bit
farther north with this boundary overnight, so will need to watch
for localized rotation with any embedded convection. The latest
SWODY1 has pulled the Marginal Risk into the western and
southwestern CWA for mainly gusty winds overnight, but instability
will be the main limiting factor. Due to the overnight timing, any
instability is expected to be weak and elevated. HREF ensemble means
bring about 200-500 joules of elevated CAPE into the region in the
warm sector overnight, but little to none is expected at the
surface. Despite some rotation possible, this will prevent any
tornadoes. We will probably not see any severe weather at all, but
given the aforementioned helicity and deep layer shear over 40 kts,
cannot rule out an isolated damaging wind gust over the southwestern
counties from Findlay to Marion between about 05 and 08Z.

Showers will end from west to east fairly quickly Friday morning
behind the exiting cold front, and any lingering showers over far
eastern Ohio and western PA will be gone by early afternoon as drier
air works in. Cold air advection and a fairly tight pressure
gradient will lead to fairly breezy W to SW winds behind the front
of 10-20 kts, with occasional gusts of 20-25 knots in the afternoon,
especially in NW Ohio and near Lake Erie. As the trough continues to
dig into the Great Lakes Friday night, a secondary cold front will
approach from the north. Moisture is limited, but lift ahead of the
front and westerly flow across the lake with weak lake induced
instability could generate a few showers in NW PA, so added slight
chance PoPs toward sunrise Saturday morning.

Highs Friday will stay in the upper 50s to low 60s as the cooler air
filters in. Lows tonight will average low/mid 50s, with upper 30s to
low 40s Friday night.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A cool dry weekend is expected with temperatures averaging about 10
degrees below average. A rather deep upper trough over Hudson Bay
will persist through the weekend and produce a cool rapid nw flow
across the region. Temperatures at 850 mb will drop to -3 to -6C.
Overnight lows will drop into the 30s and frost is expected away
from Lake Erie both Saturday and Sunday nights. High temperatures
will be in the 50s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Moderating temperatures with fair weather is expected on Monday as
weak high pressure lingers over the region. A shortwave trough will
move from the upper Mississippi Valley early Tuesday and into the
Great Lakes by Tuesday night. The associated low pressure will track
from the western Great Lakes to eastern Ontario and the trailing
cold front will cross the region Tuesday night. Showers and
thunderstorms will overspread the region Tuesday afternoon and night
with the approach and passage of the cold front. A few showers will
linger Wednesday morning before much cooler air moves into the
region. Unseasonably cool high pressure will build into the region
on Thursday and another round of frost is possible Wednesday night.
Highs on Monday and Tuesday will be in the 60s with cooler 50s for
Wednesday and Thursday. Lows temperatures in the 40s are expected
Monday and Tuesday nights with lower to mid 30s on Wednesday
night.

&&

.AVIATION /00Z Friday THROUGH Tuesday/...
Widespread VFR conditions will continue into tonight with winds
generally light and variable. Another system impacts the area
overnight, bringing a line of showers and scattered
thunderstorms west to east beginning near 06Z. Some scattered
showers may impact western terminals as early as 04Z, but should
be limited in terms of any impact. Once the primary band of
precipitation ahead of the cold front moves in, visibilities
will become MVFR and possibly IFR in the heaviest showers. For
KTOL this will begin near 06Z and for KCLE near 09Z. In
addition, ceilings will gradually begin to lower remaining at
MVFR heights ahead of the cold front, but lowering to IFR behind
it. Opted to maintain high end IFR heights as confidence is low
with how low the ceilings will go. As the cold front and
associated showers depart late morning into early afternoon, all
terminals should rebound to VFR conditions before the end of
this TAF period.

Light and variable winds this evening will increase to southeast
at 5-10 knots near the onset of precipitation. These winds will
quickly shift to northwesterly behind the cold front and
increase to 12-15 knots with gusts up to 25 knots possible.
These gusty winds will persist through the afternoon before
weakening near sunset. The exception to these wind conditions
will be KERI which will see enhanced winds of 12-15 knots with
gusts up to 25 knots from the southeast Friday morning due to
downsloping.

Outlook...Non-VFR possible in showers Tuesday.

&&

.MARINE...
Weak high pressure over the region early this evening will quickly
shift east as low pressure 29.80 inches over Missouri tracks
northeast across Lake Erie by Friday morning.  A cold front will
push east across the lake Friday afternoon.  A reinforcing cold
front will cross the Great Lakes on early Saturday.  A Small Craft
Advisory may be necessary east of Willowick with waves of 3 to 5
feet. High pressure will build east through the Ohio Valley Sunday
through Monday. Low pressure will track eastward north of the lake
on Tuesday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Garuckas
NEAR TERM...Campbell/Garuckas
SHORT TERM...LaPlante
LONG TERM...LaPlante
AVIATION...Campbell
MARINE...LaPlante