000
FXUS61 KCLE 201725
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
125 PM EDT Sat Apr 20 2024

.SYNOPSIS...
A re-enforcing cold front crosses this morning, with high
pressure building in this afternoon and persisting through
Monday. Low pressure moves into the Great Lakes on Tuesday,
lifting a warm front across the area in the morning. This will
be followed by the low`s trailing cold front Tuesday night.

&&

.NEAR TERM /THROUGH SUNDAY/...
1230 PM Update...
The primary updates with this forecast were to the cloud cover
overnight. There is more confidence that mid level clouds will
move across the area, possibly impacting the frost/freeze
potential tonight. No other changes were made.

930 AM Update...
Slight adjustments to the temperatures were made as they are
trending a bit warmer this morning than previously forecast. The
overall high temperatures for today remains unchanged. No other
updates were needed to the forecast.

Previous Discussion...
A secondary cold front will sweep southeast across the area this
morning through midday. Largely a dry passage, though have a
sprinkle mention in for Northwest PA due to some lake moisture
and higher terrain. A more noticeable feature with this frontal
passage will be cooler temperatures, with temperatures
struggling to warm today from early-morning values. Winds will
also be gusty this morning into early this afternoon, with gusts
of 25 to 35 MPH likely. A rogue gust as high as 40 MPH can`t be
ruled out later this morning as mixing deepens into 35-40 knots
of flow aloft just behind the front. Surface high pressure will
lead to continued chilly but largely dry conditions tonight and
Sunday. A shortwave and associated surface trough axis will push
through Sunday morning. 850mb temperatures of -6 to -8C overtop
lake water temperatures in the 6-10C range may yield enough
instability for sprinkles or flurries (gasp!) early Sunday east-
southeast of the lake into Northeast OH/Northwest PA. With a
rather dry airmass it will be difficult to see measurable
precip, so opted for sprinkle/flurry wording instead of a POP.
There will be some increase in clouds area-wide late tonight
into Sunday morning as this shortwave goes by with mostly sunny
conditions returning from the northwest into the afternoon.

High temperatures today will range from the mid 40s in Northwest
PA and far Northeast OH to the upper 40s to lower 50s across the
rest of our OH counties. Lows tonight will generally fall into
the low to mid 30s, warmer near and just downwind of Lake Erie.
A few interior sites may get into the upper 20s. Highs Sunday
will rebound slightly, ranging from the upper 40s to mid 50s.

Issued a Freeze Watch for parts of the area overnight tonight
into early Sunday, as a mild late winter and early spring has
allowed the growing season to begin in earnest already. With a
relatively dry weekend day today suspect some folks will be
doing outdoor work, with some plants/vegetation far enough along
in their green-out that there is susceptibility to frost/freeze
conditions. The "TL;DR" is that much of the area, except for
locations right along and then east-southeast of Lake Erie into
the snowbelt region, has decent potential to see lows fall into
the low to mid 30s tonight. This would pose a risk to sensitive
plants and vegetation. The greatest confidence in freezing
temperatures, potentially as low as the upper 20s to near 30 in
a few spots, is in the counties within the watch.

Due to a combination of factors adding uncertainty...namely,
1) Clouds and weak flow off the milder lake into the snowbelt
region of Northeast OH and Northwest PA; 2) Potential for the
approaching shortwave to bring mid-high level clouds from the
west; 3) Some potential for lower clouds and lake-modified air
from Lake Michigan to drift towards Northwest OH by early
Sunday morning; 4) A light wind persisting for most of the
night area-wide...confidence in widespread frost formation is
not extremely high (may be patchier or non-existent where winds
stay up or clouds are too persistent) with some uncertainty on
low temperatures themselves. However, the airmass will be more
than chilly/dry enough, evidenced by expected afternoon
temperatures today struggling to breach 50F with dew points in
the 20s. After (surprisingly extensive) collaboration with
surrounding WFOs and consulting probabilistic products, settled
on a Freeze Watch for the portion of our area least likely to
be impacted by the aforementioned uncertainties. Highest
confidence in lows at or below 32 and locally into the upper
20s is in the watch area. Expect day shift to be able to
upgrade most or all of the Freeze Watch to a warning assuming no
major changes, with potential for some additional counties to
be added to a Frost Advisory and/or marginal Freeze Warning if
confidence can increase. Areas most likely to be considered
outside of the current watch include more of Northwest OH if
clouds, modification from Lake Michigan, and breezes are kept to
a minimum. Another spot to watch will be interior Northwest PA.
While lake-effect clouds are likely here, the higher terrain
may aid in seeing temperatures cold advect to near or below
freezing. Could also see some counties in Northeast OH on the
fringes of the lake influence (Lorain, Summit, Portage, Trumbull
and Mahoning) needing at least a frost product if a period of
clear skies/light winds is evident in future updates.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
High pressure will build east across the area on Sunday night.
Mostly clear skies will combine with light winds of 5 mph or less
after midnight to support good radiational cooling and frost. Low
temperatures are forecast to be near the freezing mark across inland
NE Ohio and NW Pennsylvania and expect to see pretty widespread
frost. Temperatures will be closer to the mid 30s in NW Ohio but
some frost is still expected. Stay tuned for possible frost
advisories or freeze warning products.

Low level ridge axis will shift east of the area on Monday with
winds backing to southwesterly Monday afternoon/night. A warmer
airmass advects back in and temperatures will be near normal except
in Pennsylvania.

An upper level trough approaching from British Columbia will deepen
across the Midwest on Tuesday while surface low pressure moves into
the Upper Great Lakes. The airmass will be rather dry to start the
day on Tuesday but good moisture advection fed by a nearly 50 knot
low level jet will be focused towards lower Michigan and eventually
into our forecast area by Tuesday night. Will continue with a chance
of showers and thunderstorms for most areas Tuesday afternoon but
better chances arrive Tuesday evening/night. The GFS has been
consistently faster than the Canadian and ECMWF and feel these offer
better timing as it may takes some time to moisten the airmass. Pops
ramp up to 60-80 percent for Tuesday night. Given the preference
towards the slower timing, raised temperatures slightly across
southern and eastern portions of the area with many locations in the
mid 60s.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
Precipitation should exit to the east fairly quickly on Wednesday as
low pressure tracks northeast across New England. The Canadian and
ECMWF remain in good agreement with the upper level trough axis
moving off the East Coast on Wednesday night while the GFS has a
piece of polar energy diving south through the eastern Great Lakes.
This brings an anomalously strong closed upper level low of 520 dm
across New England. Still favor the better consensus offered by the
Canadian and ECMWF but will keep an eye on trends over the coming
days.

Temperatures will trend 10-15 degrees cooler for Wednesday then
moderate some Thursday and Friday. If the GFS solutions pans out it
could be even cooler. Thursday looks to be a dry day with high
pressure overhead. A chance of showers will accompany a warm front
towards the end of the week.

&&

.AVIATION /18Z Saturday THROUGH Thursday/...
VFR conditions will persist through this TAF period. Mid-level
clouds around 4-6kft persist across northern Ohio and northwest
Pennsylvania this afternoon, which should lift and become high
clouds this evening. These clouds will likely linger through the
end of this TAF period, clearing our by Sunday evening. The
primary concern with this TAF period remains the gusty northwest
winds this afternoon into the early evening hours. Winds
sustained at 12-15 knots, gusting up to 25 knots will persist
for all terminals until near sunset when they will weaken to
become northwesterly at 3-7 knots overnight and for the first
part of Sunday.

Outlook...Non-VFR possible in showers Tuesday. Non-VFR may
persist into early Wednesday.

&&

.MARINE...
Another cold front will cross Lake Erie today with westerly winds
increasing to 20-25 knots this morning, then gradually decreasing
from west to east through the afternoon. The Small Craft Advisory
has been expanded west to include the Lake Erie Islands through 1
PM. Waves on the east half of the lake will build to 5 to 8 feet.
Condition will improve tonight as a ridge builds into the Ohio
Valley.

With high pressure south of the lake, southwesterly winds of 15-20
knots will continue on the eastern half of Lake Erie on Sunday.
Conditions will likely be just below Small Craft criteria with waves
of 3 to 5 feet primarily in the open waters. Winds will be 15 knots
or less on Monday then increase out of the southwest to 15 to 20
knots ahead of low pressure moving into the Upper Great Lakes. This
system will pull a cold front east across Lake Erie Tuesday
night.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Freeze Watch from late tonight through Sunday morning for
     OHZ018>020-027>032-036>038-047.
PA...None.
NY...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for
     LEZ145>149.

&&

$$

SYNOPSIS...Sullivan
NEAR TERM...Campbell/Sullivan
SHORT TERM...KEC
LONG TERM...KEC
AVIATION...Campbell
MARINE...KEC