CLE issues Area Forecast Discussion (AFD) at Sep 21, 9:19 PM EDT484
FXUS61 KCLE 220119
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
919 PM EDT Sun Sep 21 2025
.SYNOPSIS...
A broad trough of low pressure will continue to move into the
Upper Great Lakes tonight. This trough will continue east on
Monday with a weak cold front settling south into the local area
Monday night. The front will stall just south of the area until
another low pressure system tracks from the southern Plains
towards the Central Great Lakes on Thursday.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
900 PM Update...
Scattered showers continue across the area, however there has
been a notable downward trend in lightning/rainfall rates. This
trend should continue over the next few hours, however the next
round of showers/storms may move into the area with the next
piece of energy after midnight tonight. These storms should
continue to lose steam as they move into a more stable/worked
over air mass over the next few hours. Made adjustments to PoPs
based on latest radar trends and new available high res
guidance, but additional changes may be needed as 00Z guidance
continues to trickle in and the precip to the west approaches
the local area. Either way, any overnight storms should remain
below severe limits.
Previous Discussion...
The airmass has been slow to moisten and destabilize today
which has thus far had a limiting effect on showers and
thunderstorms. A broad trough at the surface and aloft is moving
from the Upper Midwest into the Great Lakes region. An area of
light showers did move through Toledo and cloud cover associated
with this activity has spread east and limited heating through
early afternoon. A few thunderstorms are starting to develop
along a boundary from near Marysville to Marion to the lake
breeze in Cleveland. Scattered activity is expected to
increase/continue along this boundary while gradually moving
northeast this evening. ML CAPE is likely to increase to about
1000 J/Kg and effective sheer is increasing to 25- 30 knots. Our
first robust storm in southern Huron County has exhibited some
mid-level rotation and model soundings show veering flow with
height. With that said, mid-level lapse rates are weak and that
may prevent additional strengthening. We remain in a marginal
risk of severe weather and will be monitoring convection through
the evening, especially where shear may be locally higher along
the lake breeze.
One shortwave will generally pass east of the area through 03Z, but
deep layer moisture advection is expected to continued overnight and
so could additional showers and thunderstorms. Dewpoints are
forecast to be in the low to mid 60s by morning and PW values will
reach 1.7 inches by 18Z. More cloud cover is expected to be around
on Monday and that will keep instability a little lower. However, we
do expect to see showers and thunderstorms expand in coverage by
early afternoon as a stronger shortwave trough approaches the
region. Trying to place a surface boundary is going to be difficult
as a trough passes north of the area through midday. We do receive
some minimal cooling in the column and temperatures will drop back
into the 70s. Thunderstorms are expected to be efficient rain
producers on Monday and bring some much needed rain to the area. The
Storm Prediction Center has also highlighted the area in a marginal
risk for severe weather. Precipitation amounts through Monday look
to range from .75 to 1.25" of rain as the trough axis swings
through.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
By Tuesday an elongated upper level trough will extend from eastern
Quebec to the Upper Great Lakes to another trough over the Rocky
Mountains. The Great Lakes trough will drift eastward maintaining
potential for additional showers and thunderstorms on Tuesday.
Temperatures will remain in the low to mid 70s given the clouds and
showers with a general 0.25-0.75 inch of rain expected through
Tuesday night.
The pattern becomes messy by Wednesday as a broad upper level
trough over the Plains curves northeast, taking on a slight
negative tilt. Both the 12Z GFS and ECMWF have trended towards
surface low pressure reaching the Mid-Mississippi Valley by
midday on Wednesday then continuing northeast towards the Great
Lakes. It looks like a break in the rain is possible on Tuesday
night and perhaps the first part of Wednesday before the next
good round of rain arrives with this system. Temperatures
recover a couple degrees on Wednesday then cooler again for
Thursday.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Upper level and surface low pressure over the Central Great Lakes
will maintain active weather on Thursday and perhaps into Friday
before departing to the east on Saturday. Will have pops in the
forecast into Saturday with a drying trend expected towards Sunday.
Temperatures will also gradually trend up over the weekend.
&&
.AVIATION /00Z Monday THROUGH Friday/...
Scattered showers and thunderstorms associated with a shortwave
moving east across a slow-moving warm front will continue to
northeast across the area this evening into tonight. Showers/storms
should remain to the east of KTOL/KFDY for the next several
hours, but can't rule out a stray shower or thunderstorm
skimming the vicinity of these terminals at some point this
evening. In general, the greatest likelihood of showers/storms
will lie from KCLE to KMFD east with thunder chances decreasing
with the loss of diurnal instability this evening. Showers
should generally diminish and/or exit to the east between 03-06Z
tonight, however showers may linger in the vicinity of KERI
through the overnight hours. Any showers/storms that move
directly over terminals could produce non-VFR
ceilings/visibilities and breezy winds to 25 knots.
Attention will then turn upstream to the convection that is
currently moving across northern Indiana. There's still
uncertainty in how well the convection holds together as it
moves east towards the local area overnight, but currently
thinking there's a good chance of showers making it to KTOL
later tonight with showers potentially progressing east and
possibly filling in across the remainder of the CWA Monday
morning. A more potent shortwave will move into the area late in
the TAF period, which could result in scattered showers/storms.
With that being said, confidence is low due to the potential
for early-day showers and perhaps stabilizing cloud cover.
Changes to the forecast are likely as confidence in the
mesoscale environment increases. Either way, any showers/storms
late tonight through the end of the TAF period could produce
non-VFR conditions. Some guidance members are hinting at
potential for lower ceilings (either low-end VFR or MVFR) due
to the moist environment Monday morning into Monday afternoon so
have started to trend ceilings a bit lower with this update.
Winds will generally be out of the south at 6 to 12 knots with
occasional gusts to 20 knots possible. Wind direction will
likely become a bit more southwesterly on Monday afternoon.
Outlook...Periodic non-VFR are expected with scattered showers
and thunderstorms through Friday.
&&
.MARINE...
A front remains stalled in vicinity of the southern shore of Lake
Erie through this early evening as a ridge lingers over the lake.
Later this evening through the first hour or two of Monday, the
front will sweep N'ward across the lake as a warm front and as the
ridge exits to the north and east. Behind the warm front, a ridge
centered near the southern Appalachians builds through Monday night.
SE'erly winds of 5 to 15 knots veer to S'erly to SW'erly with the
warm front passage and then remain S'erly to SW'erly around 5 to 15
knots through Monday night. These winds will flirt with 20 knots at
times tonight into Monday morning. Given wind speeds are expected to
be marginal at worst, refrained from issuing a Small Craft Advisory.
Waves will remain primarily 3 feet or less through Monday night, but
occasional 4 footers are expected in open U.S. waters after midnight
tonight through the early afternoon on Monday.
A cold front drifts SE'ward across Lake Erie on Tuesday through
Tuesday night and will be followed by a ridge building from the
James Bay area. The cold front passage and subsequent building ridge
will cause SW'erly winds around 5 to 15 knots to veer to NE'erly as
waves remain 3 feet or less. The ridge will exit generally E'ward on
Wednesday through Thursday evening as the embedded high pressure
center moves from the James Bay area toward New England. NE'erly to
E'erly winds around 5 to 15 knots should veer to SE'erly Thursday
evening as waves remain 3 feet or less. On Friday, a warm front
should sweep N'ward across Lake Erie and then a cold front should
sweep SE'ward across the lake by the end of the day as a low moves
NE'ward in vicinity of Lake Erie. The warm front passage will cause
SE'erly winds around 5 to 15 knots to veer to S'erly to SW'erly and
then the cold front passage should cause winds to veer to primarily
NW'erly as wind speeds remain around 5 to 15 knots. Waves should
remain 3 feet or less.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...10
NEAR TERM...10/15
SHORT TERM...10
LONG TERM...10
AVIATION...15
MARINE...Jaszka
Source:
CLE issues Area Forecast Discussion (AFD) at Sep 21, 9:19 PM EDT---------------
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