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000
FXUS61 KCLE 060720
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
320 AM EDT Thu May 6 2021

.SYNOPSIS...
A compact area of low pressure will move east across the area
Thursday afternoon and night as an upper level trough deepens
over the Great Lakes Region. A weak trough will linger over the
eastern Great Lakes through Friday with high pressure expanding
into the region on Saturday.

&&

.NEAR TERM /THROUGH FRIDAY/...
Late evening clearing and recent rainfall has allowed for
shallow valley fog development from roughly the I-71 corridor
and eastward this morning. The clearing across the region will
be short lived in this progressive pattern with the next low
pressure system/PVA aloft on its heels and pushing towards
northwest OH at this hour. Resulting low level f-gen will push
into the western zones after 18Z in what will be a fairly slow
moving system. Subsequent secondary trough axis moves in around
15Z Friday and reinforces the POPs across the region, but this
will be a far less organized wave. All the while, the moisture
depth with these waves is limited without any appreciable feed
of low level moisture into the region, so it will translate to a
high POP event at times in the near term with relatively low
QPF overall. May get into a little bit better instability with
the third wave on Friday pushing through as 1000-700mb layer
lapse rates increase. Could see a convective cell or two stand
up enough for isolated thunder across the region.

Given the low 500mb heights and the trough axes swinging through
the CWA, the 850mb temperatures do not have the consistent
ability to stay above zero, translating into the cooler than
normal temperature regime continuing. May see a bit better
readings today given some weak warm air advection ahead of the
first surface low today, but 60 degrees will be hard to come by.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Upper level trough and its associated cold front will cross the
region Friday night with showers gradually ending from west to east.
A few lake enhanced showers may persist across NE OH into NW PA
through Saturday afternoon. We then should see a brief lull between
storm systems Saturday night. However a few showers may move into
the southwestern CWA after midnight. This stronger area of low
pressure will make for a cool rainy period Sunday into Sunday night.
Another 1/4 to 1/2 an inch of rain will be common with pockets
around an inch possible.

It will be colder than seasonal averages on Saturday and Sunday with
highs only into the 50`s. Lows should range from the middle to upper
30`s to around 40 degrees. Will have to monitor for some frost
Friday night across the southwestern CWA and maybe across NE OH/NW
PA Saturday night. The frost forecast is very uncertain at this
point with uncertainty on the amount of cloud cover that may
occur.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
We still need to get the upper level trough past us on Monday so
there will only be a slow decrease in scattered lake enhanced
showers into the evening. High pressure should then take control
Monday night into Tuesday and then persist over the region into
Wednesday night.

Only a slow warming trend is expected through the long term with
50`s to lower 60`s expected. All locations should be in the 60`s by
Wednesday. It will be chilly each night with some 30`s possible. We
will need to monitor the frost potential.

&&

.AVIATION /06Z Thursday THROUGH Monday/...
For the remainder of the overnight period, have valley fog
setting up generally east of I-77 into NE OH/NW PA. Forecast
sounding profiles from the RAP and HRRR depict shallow near
surface saturation, and given the valley fog formation in the
clearing skies tonight, added brief temporary restrictions for
CLE, CAK, and YNG. While the skies are clear for the most part
at this hour, the northwestern Ohio will see a return of cloud
cover prior to 12Z this morning, ahead of the next low pressure
system moving into the area. There will a succession of systems,
both surface and aloft, that bring somewhat prolonged chances
for off and on showers after 18Z today. The western terminals in
northwest Ohio will see the rain first, and ultimately,
restrictions once the low levels of the atmosphere saturate.
This could take a few hours to occur given the drier low
levels/boundary layer, but expect overall degrading conditions
with showers and low level clouds. Shower activity moves
eastward, but may not have any sensible affects for the far
eastern terminals in the scope of this forecast for this
issuance.


Outlook...Periods of rain showers with non-VFR possible
through Sunday. Isolated thunderstorms possible Friday
afternoon through Friday night.

&&

.MARINE...
Weak area of low pressure will move across central Ohio today then
into central PA by Friday morning. So expect to see light winds
gradually increase from the northeast through the evening. Most
locations will only see an increase to around 15 knots. The longer
fetch may get waves to 1 to 3 feet with occasional 4 footers mainly
east of the islands for tonight into early Friday morning. A cold
front will move across the lake Friday night into Saturday morning
with winds becoming northwest. Again wind speeds will be around 15
knots with te longer fetch bringing waves to at least 2 to 3 feet
into early Saturday afternoon. Winds and waves then decrease
Saturday night into early Sunday. We then await the next stronger
area of low pressure that will track near or just north of the Ohio
River through Sunday night. Northeast winds will be a bit stronger
with a small craft advisory possible for the western 2/3rds of the
lake.

&&

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

&&

$$
SYNOPSIS...26
NEAR TERM...26
SHORT TERM...MM
LONG TERM...MM
AVIATION...26
MARINE...MM