CLE issues Area Forecast Discussion (AFD) at Jul 2, 1:45 PM EDT337
FXUS61 KCLE 021745
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
145 PM EDT Tue Jul 2 2024
.SYNOPSIS...
A ridge continues to affect our region today as the parent high
pressure center moves from the eastern Great Lakes to southern New
England. This ridge exits eastward tonight as a warm front sweeps
northward through northern Ohio and northwest Pennsylvania. A weak
cold front is poised to sweep southeastward through our region
Wednesday evening through the predawn hours of Thursday morning.
Behind the cold front, a weak ridge builds from the western Great
Lakes through the balance of Thursday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
9:35 AM Update...
Minor edits to the temperature and dew point forecast to reflect
current observations and hi-res guidance.
6:05 AM EDT Update...
Forecast remains valid per latest trends in obs and model
guidance. No changes appeared necessary.
Previous Discussion...
Fair weather is expected in northern OH and NW PA through
tonight. Aloft, a ridge builds from the western Great Lakes
today and then begins to exit E'ward tonight as a shortwave
trough moves from the northern Rockies to the Upper Midwest.
Simultaneously, the surface portion of the ridge exits slowly
E'ward from our region today and is followed by the N'ward
passage of a warm front tonight. This warm front will usher-in a
much warmer and very humid air mass originating over the Gulf
of Mexico and southern Gulf Stream. Forecast models continue to
indicate the strongest frontogenesis and moist isentropic ascent
along the upper-reaches of the warm front will occur north of
our CWA, over/near Lake Huron. That is where any elevated
convection is expected to be focused overnight tonight.
The synoptic MSLP gradient is expected to strengthen gradually
through tonight as the departing surface ridge interacts with a
deepening surface trough approaching from the northern/central Great
Plains. Nevertheless, the synoptic MSLP gradient and sufficient
daytime heating of land surrounding ~72F Lake Erie will allow a lake
breeze to form late this morning. This lake breeze is expected to
penetrate up to two miles or so inland this afternoon before
dissipating late this evening. Late afternoon highs are expected to
reach the upper 70's to lower 80's within the lake breeze.
Elsewhere, late afternoon highs are expected to reach mainly the
lower to mid 80's as daytime heating is complemented by
strengthening WAA along the western flank of the low-level ridge.
Tonight's lows are expected to reach mainly the 60's to lower 70's
around daybreak Wednesday as strengthening warm/moist air advection
along the western flank of the departing low-level ridge and
especially behind the aforementioned warm front contributes to
limited nocturnal cooling.
W'erly flow aloft and embedded shortwave disturbances affect the
eastern Great Lakes and Upper OH Valley on Wednesday as the
aforementioned surface trough overspreads our CWA from the west. A
cold front will approach from the west and should reach far-western
Lake Erie and far-northwestern portions of our CWA by nightfall.
Continued low-level warm/moist air advection from the Gulf of Mexico
and southern Gulf Stream combined with daytime heating amidst peeks
of sunshine will result in a warmer and much more humid day (late
afternoon highs in the mid 80's to lower 90's), weak to moderate
destabilization of the warm/moist sector boundary layer, and PWAT
values rising to near 2.0". These projected PWAT values are near the
record-high values for 00Z/July 4th at the four upper-air stations
closest to our CWA. Daytime heating will also allow convective
mixing of the boundary layer to yield steep low-level lapse rates
and about 500 to 1000 J/kg of DCAPE amidst moderate effective bulk
shear. Given the aforementioned thermodynamic/kinematic environment,
multicell showers/thunderstorms with periods of torrential rainfall,
strong to damaging convective wind gusts, and frequent lightning are
expected to develop via low-level convergence and ascent along the
cold front, pre-front surface trough axes accompanying the
aforementioned shortwave disturbances, and downshear outflow
boundaries. Showers/storms may develop during the late morning,
but the likeliest window for showers/storms spans midday
through sunset. Since W'erly mean mid-level flow is expected to
have a significant component perpendicular to the cold front and
pre-front surface trough axes, the potential for training
convection appears limited. However, isolated flash flooding is
possible in low-lying and/or poor drainage areas impacted by
multiple rounds of showers/storms. Severe hail is not expected
since melting levels will easily exceed 10.5 kft AGL in the
warm/moist sector. Tornadoes are not expected due to a lack of
significant strengthening/veering of low-level winds with
height.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
The expectation of widespread showers and thunderstorms with a
strong to severe storm threat, as mentioned above, will continue
into Wednesday night as the cold front will move southeast across
the region. Have a larger area of categorical PoPs across the
southeast half of the area to start the period and will trend the
highest PoPs south with the timing of the cold front.
For Thursday, the question all will lie with where does the cold
front stall out. The last several forecast cycles have the front
reaching the Ohio River and settling across southern Ohio. This
could be a good omen for much of the area for the July 4th holiday
as this front will be a focus area for shower and thunderstorm
activity and will limit the amount of moisture can return north into
the region. However, some mid-level energy will ripple through the
region on Thursday afternoon and evening and with the peak heating
of the diurnal cycle, there could be some scattered convection. In
the end, have a forecast with the lowest PoPs north and highest PoPs
south, closer to the front. The Lake Erie adjacent areas are more of
a 20-30% range, whereas Central Ohio counties south of US 30 are
more of a 50-60% range.
An upper trough will enter the Upper Midwest on Friday and develop a
low pressure system west of the Great Lakes. This low will lift the
front near the Ohio River north, across the area, as a warm front.
Higher shower and storm chances will expected on Friday afternoon
and evening with the frontal passage. Rain chances will become more
scattered Friday night with the low north of the forecast area and
drier air entering ahead of the associated cold front.
Temperatures through the period will be near normal in the 80s.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
All in all, the forecast continues to trend toward a generally quiet
weekend after several days of unsettled weather across the region. A
low pressure system will be moving east across the Great Lakes on
Saturday, north of the forecast area. This low should allow for a
cold front to sweep through earlier in the day and there are some
lower rain chances to start on Saturday with the highest chances
east. Some upper ridging will build into the region for Saturday
night into Sunday and support surface high pressure across the
region. This will allow for a generally dry forecast through Sunday
night. An upper trough and associated surface cold front will
approach the forecast area on Monday and some scattered rain chances
could return to the region. Temperatures through the period will be
generally seasonable in the 80s.
&&
.AVIATION /18Z Tuesday THROUGH Sunday/...
VFR conditions remain across all terminals through the period
as a ridge of high pressure gradually builds eastward. Showers
and scattered thunderstorms are possible ahead of a cold front
late Wednesday afternoon and evening. The bulk of the showers
and storms will occur outside the current TAF period but have
begun to mention -SHRA at western terminals (~16Z) and VCTS in
the KCLE 30 hour TAF.
Southeasterly winds 8-10 knots will turn southwesterly
overnight tonight before increasing to 10-15 knots with gusts
20-25 knots by late Wednesday morning. There remains to be a
lake breeze impacting KERI this afternoon with the expectation
that winds will return generally southerly by 00Z/Wed.
Outlook...Non-VFR expected with periodic/scattered
showers/thunderstorms Wednesday afternoon through Saturday.
&&
.MARINE...
A warm front will lift north toward Lake Erie today. The front will
struggle to clear the lake during the daytime hours and southeast
flow will become brief northeast flow during the late afternoon and
early evening hours. The front will fully cross the lake tonight and
southerly flow will take over and increase into Wednesday as a cold
front approaches the region. The offshore flow could get strong
enough on Wednesday to merit a marginal Small Craft Advisory with
wind touching 20 knots. The cold front will cross the lake by
Wednesday night and light westerly flow will become favored across
the basin. The front will stall over the Ohio River for Thursday and
light generally offshore flow will be favored. This front will lift
back north as a warm front on Friday and slightly stronger south to
southeast flow will return to the lake. A low pressure system will
move north of the lake on Friday night into Saturday and a stronger
pressure gradient across the region will allow for increasing
southwest flow and another Small Craft Advisory could be needed.
Shower and storm chances are in place for Wednesday through Saturday
with several fronts moving near and across the lake. Some storms may
need a short fused marine warning headline, especially on Wednesday
and Friday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Iverson/Jaszka
SHORT TERM...Sefcovic
LONG TERM...Sefcovic
AVIATION...Iverson
MARINE...Sefcovic
Source:
CLE issues Area Forecast Discussion (AFD) at Jul 2, 1:45 PM EDT---------------
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