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000
FXUS61 KCLE 110926
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
508 AM EDT Thu Apr 11 2024

.SYNOPSIS...
A warm front will drift generally northward through our region
this morning through evening as a consolidating and strengthening
low moves north-northeastward from near the Middle Mississippi
Valley toward southern Lake Huron. A cold front trailing this
low should sweep eastward across our area late this evening
through the predawn hours of Friday morning as the low moves
farther north-northeastward toward Georgian Bay and strengthens
further. Behind the low, a trough lingers across the eastern
Great Lakes and Upper Ohio Valley on Friday before a ridge
builds from the Upper Midwest on Saturday.

&&

.NEAR TERM /THROUGH FRIDAY/...
Aloft, a ridge exits E`ward from our CWA through tonight.
Simultaneously, a trough moves from the north-central United
States toward the western Great Lakes and becomes negatively-
tilted as a potent mid/upper-level jet streak rounds the base of
the trough. Significant MSLP falls and large-scale tropospheric
ascent accompanying mid/upper-level divergence downstream of
the trough axis and within the left-front quadrant of the jet
streak will allow a surface low to consolidate, deepen rather
quickly, and track NNE`ward from near the Mid MS Valley early
this morning to near Georgian Bay by daybreak Friday morning.
Accordingly, a diffuse surface warm front accompanying the low
should drift generally N`ward through our CWA this morning
through evening and be followed by a trailing surface cold front
poised to sweep generally E`ward through our CWA late this
evening through the predawn hours of Friday morning. Low-level
WAA ahead of the warm front and within the warm sector is
forecast to contribute to this afternoon`s highs reaching mainly
the 60`s. Strong low- level CAA behind the cold front should
allow lows to reach the lower to mid 40`s around daybreak Friday
morning.

The aforementioned low pressure system will continue to exhibit
an impressive warm conveyor belt tapping into abundant moisture
from the Gulf of Mexico and/or southern Gulf Stream (e.g.
forecast PWAT`s exceed the 90th percentile per SPC sounding
climatology data for nearby upper-air stations) while undergoing
moist isentropic ascent aloft. The result will be continued
abundant cloud cover and periods of rain, steady to heavy at
times, along and ahead of the cold front. The isentropic ascent
aloft may release weak, yet sufficient and elevated CAPE to
trigger periodic thunderstorms with torrential rainfall,
especially late this morning through the wee hours of Friday
morning. Refrained from issuing a Flood Watch given training
convection is expected to be limited to the cold front itself,
where S`erly to SW`erly mean mid-level flow is expected to
roughly parallel the front, yet average 20 to 30 knots and
result in fairly fast-moving training cells and localized
potential for flash flooding.

SPC has maintained a risk of severe thunderstorms across much
of our CWA, especially roughly along and east of I-71. The
potential for severe thunderstorms is contingent on the degree
of daytime heating and resulting destabilization of the humid
warm sector boundary layer. Latest NBM mixing height guidance
suggests appreciable peeks of sunshine, greater/deeper diurnal
convective mixing of the boundary layer, and resulting greater
boundary layer CAPE/steeper low-level lapse rates should be focused
across far-NE OH into NW PA late this morning through perhaps this
early evening. These areas may have surface-based MUCAPE grow to
around 500-750 J/kg and DCAPE grow to near 500 J/kg amidst mixed
layer LCL`s less than 1k meters AGL, moderate to strong effective
bulk shear, and strong surface-based ESRH stemming from SE`erly
surface winds veering quickly toward SW`erly and strengthening
quickly with height in the low-level atmospheric column. Given the
projected thermodynamic and kinematic environment, isolated to
scattered multicell and supercell thunderstorms capable of producing
several tornadoes and sporadic damaging convective gusts may form
via low-level convergence along the diffuse surface warm front and
any outflow boundaries in far-NE OH and NW PA. This area is roughly
where SPC has maintained an enhanced risk of severe storms (risk
level 3 of 5) in their latest convective WX outlook from ~2 AM EDT
this morning. A lack of steep mid-level lapse rates and limited hail
growth zone MUCAPE should greatly curb severe hail potential. Any
severe thunderstorms should end early this evening as the warm
sector boundary layer stabilizes via nocturnal cooling.

Surface troughing lingers over our CWA on Friday as the surface
low moves NE`ward toward southwestern QC, occludes, and becomes
vertically-stacked with a developing mid/upper-level low within
the aforementioned trough aloft. Cyclonic SW`erly flow aloft
should veer to NW`erly over our CWA as embedded shortwave
disturbances revolve around the low aloft. Periodic rain showers
and a few thunderstorms are possible, especially during the late
morning through afternoon hours as convergence/associated ascent
along surface trough axes release weak potential instability and
the combination of limited daytime heating and much colder air
farther aloft results in self-destructive sunshine. A Wind
Advisory may be needed as diurnal convective mixing of the
boundary layer taps into stronger flow aloft and contributes to
W`erly surface winds gusting as high as 40 to perhaps 50 mph
during the late morning through early evening. Daytime highs
should reach the upper 40`s to mid 50`s as net low-level CAA
continues behind the recent cold front passage.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
The deep mid/upper longwave trough axis will start to lift into the
eastern Great Lakes and New England Friday night, with the surface
low lifting up east of James Bay. This will allow the deep
wraparound moisture and lift to finally pull away, and with broad
surface high pressure over the Mississippi and Tennessee Valleys
building in from the southwest, the lingering upslope showers over
far NE Ohio and NW PA will gradually end. Expect all areas to be dry
by Saturday morning setting up a mostly sunny day with the surface
high ridging into the area. Temperatures will be a solid 5-10
degrees warmer Saturday in response to the sunshine and rising mid-
level heights as the mid/upper trough continues to lift out.

The dry weather will not last long as a northern stream mid/upper
shortwave remains progged to crest a building mid/upper ridge over
the Plains and drop ESE through the Great Lakes Saturday night into
Sunday. This feature will act as a focus for showers and
thunderstorms along a warm frontal boundary that will lift into the
area Saturday night. The combination of the shortwave and lingering
NW mid/upper flow across the New England states will give the warm
front resistance, so it will likely become quasi-stationary over
north central or NE Ohio by Sunday keeping at least scattered
showers/storms in place through Sunday. So at this time, have slight
chance to chance PoPs Saturday night increasing to high
chance/likely over NE Ohio and NW PA Sunday. Persistent warm/moist
advection driven by a 30-40 knot westerly low-level jet overtop of
south to southeasterly low-level flow could induce enough low-level
and deep layer shear for a marginal severe risk Sunday (mainly
damaging winds and hail), but a bigger threat could be locally heavy
rainfall since these NW mid/upper flow patterns overtop of more
southerly low-level flow and a boundary laying NW to SE in the area
can sometimes produce training convection. The latest NAEFS Ensemble
Situational Awareness Table projects PWATs of 0.75 to 1 inch which
is around the average of daily climatology, but the mean integrated
water vapor transport (IVT) is projected to be over the 90th
percentile near the boundary in NE Ohio and NW PA, so that speaks to
the persistent moisture advection into the boundary. While the
rainfall rates should not be anything crazy with these values, the
wet antecedent soil conditions from all of the recent rain could
lead to at least nuisance flooding of low-lying and poor drainage
areas, and/or additional river rises, so the situation will continue
to be monitored. The boundary should push back southward behind the
shortwave Sunday night, so expect conditions to dry south from north
to south.

Highs Saturday will warm into the mid 50s to low 60s, except low 50s
in far NE Ohio and NW PA. Sunday will be much warmer, but with the
warm frontal boundary bisecting the area, expect low/mid 70s in NW
and north central Ohio and mid 60s to low 70s in NE Ohio and NW PA.
Lows Friday night will fall into the upper 30s/low 40s, with
low/upper 40s Saturday night and mid 40s/low 50s Sunday night.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
Weak surface high pressure will build into the region Monday keeping
the frontal boundary south of the area. The blended forecast wanted
to bring chances for convection into the southern areas, but kept
the forecast dry since the high should win out keeping the boundary
south until Monday night. The front will start to return northward
as a warm front Monday night and Tuesday in response to a strong
mid/upper shortwave trough ejecting from the southern Rockies across
the southern and central Plains which will induce a deepening
surface low lifting north across the Plains Tuesday. Warm/moist
advection and isentropic ascent could bring a few showers and
thunderstorms along the retreating boundary Monday night into early
Tuesday, but the more organized precipitation may hold off until
Tuesday night and Wednesday when the associated cold front moves
into the area. Lots of uncertainty with this system 6 to 7 days out,
so have broad chance PoPs Monday night through Wednesday. Strong
warm air advection ahead of the system and a building mid/upper
ridge over the east coast will push temperatures well above normal
Tuesday and Wednesday.

Highs Monday will range from the low to mid 60s near the lakeshore
to the low to mid 70s inland, warming into the mid to upper 70s
areawide Tuesday and Wednesday. Some areas could exceed 80 in this
pattern, but went conservative on temperatures for now.

&&

.AVIATION /06Z Thursday THROUGH Monday/...
Cyclonic S`erly to SW`erly flow aloft persists over our region
through 06Z/Fri as a trough moves from the north-central United
States toward the western Great Lakes. Simultaneously, a surface
trough lingers over our region as a consolidating low moves
NNE`ward from the Mid-MS Valley to near southern Lake Huron and
deepens rapidly. This low track should allow a warm front to
sweep generally N`ward through our region through ~18Z/Thurs,
while the trailing cold front should begin to sweep generally
E`ward after ~01Z/Fri and near a roughly KCLE to KCMH line by
06Z/Fri.

Our regional surface winds should veer gradually from NE`erly
to SW`erly with the passage of the warm front and eventual
approach of the cold front. These winds are forecast to be
around 5 to 15 knots with gusts up to 20 to 25 knots at times.
The cold front passage will cause winds to veer quickly to
W`erly to NW`erly. The post-cold front winds are expected to be
around 15 to 25 knots with gusts up to 25 to 35 knots.

Widespread low clouds, associated VFR to IFR ceilings, and
periods of rain, steady to heavy at times, are expected through
the TAF period as the potent low pressure system impacts
northern OH and NW PA. Thunderstorms are possible Thurs
afternoon through 06Z/Fri, especially roughly along and east of
I-71. Brief and erratic surface gusts up to 35 to 45 knots may
accompany these storms Thurs afternoon through early evening.
Visibility is expected to vary between VFR and IFR in rain.

Outlook...Non-VFR expected with periodic rain showers and
thunderstorms on Friday through Monday.

&&

.MARINE...
The quiet stretch of marine weather will end later today through the
start of the weekend as a strong Spring low pressure system impacts
the Great Lakes. Winds will turn SE today and increase to 15-20
knots as the low approaches from the Mississippi Valley. As the low
lifts into Lower Michigan tonight, the trailing cold front will
blast across the lake and veer winds to the WSW, with speeds
increasing to 20-30 knots. This will build 7-10 foot waves in the
central and eastern basins tonight and Friday as W winds continue at
20-30 knots Friday. Winds will turn a bit more WNW as the low
departs toward James Bay Friday night and Saturday morning, with
speeds gradually decreasing to 15-25 knots. Winds will then turn WSW
and further decrease to 10-15 knots Saturday afternoon as high
pressure builds over the region. SW winds of generally 10-15 knots
are then expected the rest of the weekend, becoming light and
variable Sunday night into Monday.

Issued Small Craft Advisories for the entire lake for this system.
The W to WSW winds will get near gale force late tonight and Friday,
but the vast majority of high resolution model guidance keeps
sustained speeds below 34 knots, so high end small craft headlines
should be sufficient. Needless to say, the lake will be dangerous
tonight into Saturday.

&&

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

&&

$$

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