401 
FXUS61 KCLE 100601
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
201 AM EDT Thu Oct 10 2024

...06z TAF Aviation Forecast Update...

.SYNOPSIS...
High pressure builds eastward from the western Great Lakes 
through Thursday. On Friday, a warm front will lift eastward 
across Lake Erie followed by a cold front on Saturday. Low 
pressure will track northeastward across the Lower Great Lakes 
Sunday into Monday.

&&

.NEAR TERM /THROUGH TODAY/...
9:30 PM Update...
Adjusted temperatures and dewpoints to reflect current
observations across the region. No other changes were made to
the forecast at this time. Frost Advisory for Southern Erie and
Crawford (PA) Counties is in effect from 2 AM to 9 AM Thursday
morning as overnight lows will dip into the mid 30s. 

Previous discussion...
Cyclonic NW'erly flow aloft persists through tonight. A
relatively-strong shortwave trough embedded in the flow aloft
advances SE'ward across eastern Lake Erie and vicinity through
this afternoon and early evening. At the surface, a ridge
continues to build from the western Great Lakes. Primarily fair
weather is expected due to stabilizing subsidence accompanying
the ridge. However, a few rain showers associated with moist 
isentropic ascent aloft, ahead of the shortwave trough axis, may
impact eastern Lake Erie through this early evening. Isolated to
scattered lake-effect stratocumuli are expected over and
downwind of ~19C Lake Erie through tonight as sufficiently-
cold/moist mean low-level flow veers from NW'erly to N'erly.
Mainly clear to partly cloudy sky, easing surface winds, and 
limited humidity at/near the surface will promote efficient 
nocturnal cooling this evening through daybreak Thursday 
morning. Low temperatures are expected to reach the mid to 
upper 30's in the deeper valleys of Crawford County and southern
Erie County in PA. This is where at least patchy frost 
formation is expected around daybreak. A Frost Advisory has been
issued from 2 AM to 9 AM EDT Thursday for Crawford and southern
Erie Counties. Elsewhere in those counties, lows are expected 
to reach the upper 30's to mid 40's due to weakening onshore 
surface flow from Lake Erie. In northern OH, lows are expected 
to reach mainly the upper 30's to mid 40's around daybreak. 
However, isolated lows in the mid 30's and patchy frost 
formation are expected in interior valleys of northeast and 
north-central OH. Refrained from issuing a Frost Advisory for 
those areas due to the expected more-isolated nature of frost 
formation.

NW'erly flow aloft transitions gradually from cyclonic to
anticyclonic on Thursday through Thursday night as a ridge 
aloft builds slowly from the north-central United States and 
vicinity to the Great Lakes and vicinity. The aforementioned 
surface portion of the ridge continues to impact our CWA as the 
core of the ridge wobbles SE'ward from near Lower MI to near the
Upper OH Valley. Fair weather and mainly clear to partly cloudy
sky persist as stabilizing subsidence accompanies the ridge.
Lake-effect stratocumuli are expected to persist over and
downwind of ~19C Lake Erie as sufficiently-cold/moist mean low-
level flow backs from N'erly toward W'erly. Late afternoon highs
are expected to reach the 50's in northwest PA, the upper 50's 
to lower 60's in northeast OH, and mainly the mid to upper 60's
farther west. Thursday night is expected to be colder as mainly
clear sky, easing surface winds, and low humidity at/near the 
surface promote efficient nocturnal cooling Thursday evening 
through daybreak Friday. Widespread lows in the lower to mid 
30's are expected from roughly Marion County, OH to southern 
Erie County, PA and points south. This is where fairly 
widespread frost formation is expected. Another Frost Advisory 
will likely be needed. Lows are forecast to reach mainly the 
upper 30's to lower 40's farther north in our CWA.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
Quiet weather will continue through the day on Friday but will be 
replaced with more unsettled weather early Saturday night as a cold 
front sweeps across the region. There appears to be limited 
moisture return associated with the front, but can't rule out the 
possibility of showers across the northern counties. The front will 
become almost stationary across the southern part of the CWA and 
down in central OH for a much of the on Saturday. There will be 
northerly flow across the lake, so there is some potential for most 
to see some precipitation, with a greater chance (30% PoPs) for the 
northern half of the CWA. Moving into Saturday night PoPs will 
increase for everyone in the region as a low pressure system moves 
in from the west. There is more uncertainty regarding this system in 
terms of its potency and location. Will talk more on this in the 
Long Term as most impacts will occur during that time period. 

Temperatures for Friday and Saturday should be mild. On Friday, the 
western half will see temperatures in the mid to upper 70s and the 
eastern counties will be in the low 70s, upper 60s. For Saturday, 
most will have highs in the mid to upper 60s. Lows for Friday and 
Saturday will be in the low 50s with some locations in the eastern 
counties seeing high 40s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
For aforementioned low pressure system, the most recent run of the 
ECMWF has slowed down the surface low pressure, though still quicker 
than the GFS. The upper level support for the system is in more 
agreement on when the trough will sweep through the region as the 
ECMWF looks to have come back in its most recent run. Nonetheless, 
most runs have plenty of jet support moving in from interior Canada 
with the GFS having the strongest support. With this upper level 
support, there does look to be continued chance for precipitation 
behind the actual frontal passage on Sunday. Though, whether that's 
where the majority of the precipitation comes from or if it's with 
frontal passage itself is still in disagreement. The surface low 
should move out of the region fairly quickly by Monday morning with 
the upper level trough deepening down into Eastern Canada and 
lagging a bit behind. As it deepens, there will be strong 
northwesterly flow brining chillier weather and showers through 
nearly the end of the period. PoPs will be higher (60-70%) Sunday 
through early Tuesday mainly for the eastern two-thirds of Lake Erie 
and counties west of I-80 with the rest of the area between 30-50%. 
This will mainly be driven by lake effect so differences in chances 
will be driven by how much moisture is left in the wake of the 
system and wind direction. PoP chances will decrease as we move into 
the middle of next week as the upper level trough starts to move 
eastward and a ridge builds in behind. 

Highs on Sunday will be in the 60s for much of the CWA with some 
southern counties hitting low 70s. Temperatures on Monday and 
Tuesday behind the surface cold front will be down into the mid to 
low 50s with some higher elevation areas in NE OH and NW PA not 
making it out of the upper 40s. Wednesday should see gradually 
warming with high in the mid to upper 50s. Overnight lows on Monday 
will be in the low 40s, then in the mid to upper 30s on Tuesday and 
Wednesday for everyone except the counties closest to Lake Erie. 
There will be a potential for frost mid-week next week with calmer 
overnight winds and clearing skies, though there is still some 
uncertainty.

&&

.AVIATION /06Z Thursday THROUGH Monday/...
VFR conditions will prevail for this 06z TAF update. A large 
high pressure system is in control of our weather pattern across
the Great Lakes and Ohio Valley. Fair weather conditions along 
with mostly clear skies will continue over the next 24 hours 
with no aviation weather concerns. Winds will be light 5 to 10 
knots from the north or northeast this morning into the
afternoon. Winds will gradually become easterly by this evening
less than 5 knots. Most areas will see the wind go calm or 
light and variable later this evening as the center of the high
pressure tracks over the area. 

Outlook...Scattered rain showers with non-VFR conditions 
possible late Saturday into Sunday associated with a cold front.
Lake Effect clouds and scattered rain showers will be likely
Sunday through Tuesday night, especially downwind of Lake Erie 
and the Snowbelt region. 

&&

.MARINE...
A Small Craft Advisory remains in effect for Lake County eastward as 
winds have been 15-25 knots and waves 3-5 feet. Winds will shift to 
be more northerly and weaken tonight into Thursday as high pressure 
moves across the region. The lake will remain choppy though through 
Thursday evening. Winds and Waves will start to build again as a 
cold front approaches the lake Friday into Friday evening. Winds 
will be southwesterly Friday at 15-25 knots and continue until 
frontal passage Saturday morning then will shift out of the north. A 
Small Craft Advisory may be needed for that time frame for zones 
east of Avon Lake. Calmer conditions will return Saturday and 
Saturday night ahead of the next system. 

A stronger cold front is expected to traverse the lakes on Sunday. 
There is still some disagreement on the location of the low which 
may impact wind forecast, regardless the lake will be fairly choppy, 
especially after frontal passage. Winds will be out of the south at 
10-15 knots then transition to northwesterly behind the front Sunday 
afternoon/evening. There will be a fairly strong gradient behind the 
front and winds will be 20-25 knots for the majority of the lake so 
a small craft will likely be needed. As mentioned above, with the 
uncertainty in the placement of the low, there is lower confidence 
in the forecast at this time.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...Frost Advisory until 9 AM EDT this morning for PAZ002-003.
MARINE...Small Craft Advisory until 4 AM EDT early this morning for 
     LEZ147>149.

&&

$$

SYNOPSIS...Iverson
NEAR TERM...Iverson/Jaszka
SHORT TERM...Kennedy
LONG TERM...Kennedy
AVIATION...Griffin
MARINE...Kennedy