045 
FXUS61 KCLE 120806
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
406 AM EDT Tue Sep 12 2023

.SYNOPSIS...
Low pressure tracking through the central Great Lakes this 
morning will drag a cold front across the region today. A trough 
will persist across the Great Lakes region through Wednesday 
before high pressure builds in Thursday and remains in place into 
next weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Nothing has really changed with the forecast for the weather 
system coming in today and exiting the area by this evening.
A large upper level trough will continue to dig across the Great
Lakes and Ohio Valley regions today through tomorrow. A cold
front is currently located across central Michigan stretching
down to near the Illinois/Indiana state line. Along and ahead 
of this cold front are areas of light to pockets of moderate 
rain showers. These showers have already started to move into 
northwest Ohio and western Lake Erie this early morning.

We are not expecting anything real exciting from this cold
front move through the region. Moisture content in the
atmosphere ahead of this front is on the lower side of things. 
Overcast skies have already spread over much of our local area. 
Cloud and scattered rain showers will keep our temperatures held
down a bit which will also keep instability very low as well. 
With the lack of any thermodynamics for the cold front to work 
with, we are not expecting any organized or strong convection to
develop. We may barely have enough energy in our atmosphere to 
get a rumble of thunder today. 

The general expectations for today will be light rain showers
will move across our area from west to east. Rainfall amounts
today will be on the light side of 0.05" to 0.20". Temperatures
will be the mildest before cold front passes through. Max temps
today will be in the upper 60s to lower 70s. The rain chances
will gradually decrease later this afternoon into the evening
from west to east as the front exits the area.

The surface flow will be a light northerly flow by this evening
into the overnight. Skies will be able to clear out for
northwest Ohio by early evening. Lake effect clouds will take
over the skies for much of north central and northeast Ohio as
well as NWPA tonight and Wednesday. 850 mb temperatures will
cool off to around 5C by late Wednesday which means we will have
some scattered lake effect rain showers and misty, drizzle 
developing tonight and lasting through Wednesday evening. The 
main trough axis doesnt pass over our area until Wednesday 
evening. The weather will be a little nicer away from the 
lakeshore and Snowbelt areas on Wednesday. High temperatures 
will stay in the 60s. Additional rainfall amounts from the lake 
effect showers will be light as well with another tenth of an 
inch possible. 

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
On Wednesday night, the large upper-level closed low will still 
encompass the Great Lakes region, those the circulation center will 
be relatively displaced to the northern in western Quebec. The axis 
of mid-level vorticity will extend southward to the local forecast 
area 00Z/Thu, making its way east Wednesday night through Thursday. 
In the lower-levels cool temperatures will bottom out around 4-6 deg 
C by 12Z/Thu. This cool air aloft should produce moderate lake-
induce instability, and thus some lake effect rain showers, with 
northwest flow directly lake effect showers towards the typical 
snowbelt region areas of Northeast Ohio and Northwest Pennsylvania. 
Conditions for lake effect rain actually become less favorable 
through Wednesday night and Thursday morning, with high pressure 
building in and warming mid-levels as heights rise with the 
departing upper-level low. Despite favorable instability, flow is 
relatively weak (limiting moisture flux off of Lake Erie) and many 
models have limited moisture due to the building surface high and 
upper-level ridge. For now, will hold with slight chance PoPs 
through 12Z/Thu, though could see targeted higher PoPs as we get 
into range of hi res model guidance.

High pressure becomes centered over the local forecast area by 
Thursday afternoon/night. While some lake effect clouds or isolated 
showers/sprinkles may linger into Thursday morning, most of the 
region should see some sun by Thursday afternoon. High pressure 
remains over the area through Friday night, with sunny/clear skies. 
The cool airmass put into place by the low pressure system remains 
in place on Thursday, modulating a bit on Friday, though still 
slightly below normal. It'll feel very much like fall this week.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
An upper-level ridge and associated surface high pressure remains 
over the region on Saturday, though gradually dissipates as an upper-
level trough approaches from the west. Saturday should be a touch 
warmer than Friday, with slightly more cloud cover. By 
Sunday/Monday, we introduce low-chance PoPs (20-30%) associated with 
this approaching low pressure system. No drastic temperature changes 
expected with this system.


&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
The main weather concerns for aviation with this TAF update will
be ceilings lowering to MVFR and some locations to lower MVFR
later this morning through the afternoon. Clouds are increasing
from west to east through the predawn hours. Scattered light
rain showers will also move in this morning through the 
afternoon as a cold front pushes through the area. Eventually,
we will moisten up enough later this morning through the early
afternoon to have slight visibility reductions dropping to 4sm 
or 5sm due to the light rain showers and misty conditions.

Ceilings and conditions will improve after the frontal passage
today with VFR returning to most sites by this evening or the 
end of the TAF period. Skies will clear out first over northwest
Ohio including FDY and TOL. Overcast ceilings will hold across 
much of NEOH and NWPA through this evening into the overnight 
due to lake effect clouds coming off Lake Erie. YNG and ERI as 
well as much of the Snowbelt areas will stay with MVFR ceilings 
through the overnight. Scattered lake effect rain showers will 
also continue for the Snowbelt TAF sites into the overnight 
hours. 

Winds will be light 5 to 10 knots during the next 24
hours. Light south-southwesterly winds this morning will shift
to more westerly during the day today and eventually becoming
northwesterly by this evening and tonight. 

Outlook...Non-VFR possible in lake effect rain showers, mainly 
for the areas of the Snowbelt downwind of Lake Erie, Tuesday 
night through Wednesday.

&&

.MARINE...
Low pressure currently over western Lake Huron will continue to make 
eastward progress today into Ontario and then western Quebec by 
tonight. A cold front extending from this low will move east across 
Lake Erie today. Winds ahead of the cold front will be out of the 
south, quickly veering to out of the west with the frontal passage 
today. Strongest winds are expected with that westerly flow when 
winds of around generally in the 15-18 knot range are expected, 
though winds could periodically reach ~20 knots. Conditions are 
expected to be choppy and could become quite close to small craft 
advisory conditions, primarily for the eastern half of Lake Erie. 
For now, will resort to monitor observations due to low confidence.

Winds turn to out of the northwest this evening with a weak 
secondary cold front or surface trough. The initial wind shift may 
have winds up to 18 knots accompany it, before settling in the 12-15 
knot range. This will probably be enough to produce choppy nearshore 
waters tonight through Thursday, though it's unlikely a small craft 
advisory will be needed as wave heights look to mostly be in the 2-3 
ft range with the occasional 4 footer. High pressure builds in 
Thursday through the weekend, easing conditions on Lake Erie.

&&

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

&&

$$

SYNOPSIS...Griffin
NEAR TERM...Griffin
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Griffin
MARINE...Saunders