642
FXUS61 KCLE 171955
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
355 PM EDT Fri May 17 2024

.SYNOPSIS...
Weak low pressure aloft will slowly push a cold front across the
region tonight and Saturday. The front will wash out over the
Appalachians late Saturday followed by high pressure building in
Saturday night. The high will remain in control through Tuesday
before low pressure and a cold front approach by Wednesday.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
A weak but broad mid/upper trough remains across the Great Lakes and
Ohio Valley this afternoon, with associated weak surface low
pressure just south of James Bay extending a cold front through
Lower Michigan and Indiana. Synoptic forcing and deep layer wind
profiles are very weak, but upper-level diffluence and the right
entrance region of a 75-85 knot H3 jet streak lifting through
the southern Great Lakes generated widespread shower activity
this morning since plenty of low-level moisture is in place. The
steadiest showers are currently exiting far eastern Ohio and
western PA coincident with the aforementioned jet streak lifting
out of the region, but breaks in the cloud cover are generating
weak to moderate instability characterized by SBCAPE of
1000-1500 J/Kg in NW and north central Ohio. This combined with
continued low-level moisture (dew points low/mid 60s) and upper
diffluence and low-level confluence ahead of the cold front is
supporting the development of diurnal convection. Doppler radar
and visible satellite loops show most of this developing from
north central Ohio through the central highlands at the time,
but development is also taking place in Lower Michigan away from
the lakes. With all of this in mind, all areas could see
passing showers or thundershowers this afternoon and evening,
but the greatest potential is over the southern and eastern
counties from roughly Mt. Vernon to Youngstown, so put the
highest PoPs there through the evening. Since the flow aloft is
weak, deep layer shear values will only be 10-15 knots, so
severe weather is not expected. The only concern with the
convection will be locally heavy rainfall that could lead to
localized, nuisance flooding. PWATs remain in the 1.3 to 1.5
inch range in much of the area which is around the 90th
percentile of daily climatology for the date, and RAP forecast
soundings show fairly tall, skinny CAPE with freezing levels a
little above 700 mb. This combined with the weak flow profile
and the flow parallel to the front will allow for some slow
moving convective cells with efficient rainfall rates of 1-2
inches per hour. Any issues would likely be if convection can
train.

The weak mid/upper trough axis will further weaken and move east of
the region tonight and Saturday allowing shortwave ridging and broad
surface high pressure to nudge in from the west by Saturday night,
but it looks to be a slow process since two northern and southern
stream weak troughs are pretty separated from the main jets aloft.
This will cause the weak cold front to slowly progress east and
southeast across the region tonight and Saturday before washing out
near the Appalachians. Most areas will dry out tonight, but with the
front and associated low-level moisture taking their time exiting on
Saturday, diurnally driven convection will develop again from late
morning through the afternoon, mainly east of I-77. Coverage should
however be less than today, but locally heavy downpours could occur.
All areas will dry out Saturday night as the high builds in.

Lows tonight will range from the upper 50s to around 60, with highs
Saturday in the upper 70s/low 80s in NW and north central Ohio where
more sunshine occurs, but mid 70s in NE Ohio and NW PA. Lows
Saturday night will fall into the mid/upper 50s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The weather pattern will shift to a hotter and more summer like for
later this weekend into early next week. An upper level ridge of
high pressure will develop and expand over the Ohio Valley region
Sunday and Monday. The main storm track will shift northward into
the Upper Midwest and Upper Great Lakes region for a few days. With
high pressure in control, we will expect fair weather conditions
with mostly sunny to partly cloudy skies. High temperatures on
Sunday afternoon will range from the lower to middle 80s. There
could be a light lake breeze Sunday afternoon closer to the
lakeshore that may keep temperatures in the upper 70s. We will add
another degree or two for Monday afternoon with high temperatures
ranging from the lower to upper 80s. We should stay dry Sunday
through Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
High pressure will continue to remain in control of our weather on
Tuesday keeping us very warm and dry. Temperatures will be once
again in the middle to upper 80s. By Tuesday night, the upper level
ridge of high pressure will begin to break down and a series of
shortwave troughs will swing through the Great Lakes region by the
middle of next week. A slow moving cold front will start to slide
into the Lower Great Lakes region and Ohio Valley region late
Tuesday night through late Wednesday night. Showers and
thunderstorms will become likely by the middle of next week.
Temperatures will also be slightly cooler with the rain chances in
the area Wednesday through early Thursday.

&&

.AVIATION /18Z Friday THROUGH Wednesday/...
Drier air is slowly working into western and northern areas this
afternoon allowing KTOL, KFDY, and KCLE to mainly become VFR,
but steadier showers continue farther south and east where MVFR
remains prevalent at KCAK, KMFD, KYNG, and KERI. Expect the
steadiest showers to continue to exit this afternoon, but
scattered showers and a few pockets of thunder will redevelop,
so carried VCSH at all sites into this evening before gradually
ending from NW to SE. The theme should be better cigs and vis
late this afternoon and evening with much more scattered shower
coverage compared to this morning.

Moving into tonight, confidence continues to increase on
impactful fog since most areas saw rainfall today, and there
will be plenty of lingering low-level moisture and
light/variable winds. Think mist will start lowering
visibilities after 04Z, but the biggest risk for dense fog will
be between 08 and 12Z, so used TEMPO groups. The fog and
mist/low clouds should improve rather quickly Saturday morning.

SW winds of 5-10 knots this afternoon will become light and
variable tonight into Saturday morning.


Outlook...Non-VFR possible with showers and thunderstorms
Saturday and again on Tuesday.

&&

.MARINE...
Overall the weather forecast for Lake Erie will remain quiet this
weekend into early next week. High pressure will return over the
lake this weekend with a light northeast flow under 10 knots for the
weekend. A warm front will lift across the lake Monday with a return
of southeast flow over the lake. Southerly flow will continue to
increase up to 15 knots Tuesday and Wednesday ahead of a low
pressure system that will move through the Upper Great Lakes for the
middle of the week. No marine headlines are expected at this
time.

&&

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

&&

$$

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