National Weather Service Raw Text Product

423 
FXUS61 KCLE 010013
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
813 PM EDT Sat Oct 31 2020

.SYNOPSIS...
A warm front will advance northward through the region this 
evening. A cold front will quickly move through the area 
Sunday morning as a low moves eastward across James Bay and 
northern Quebec. Behind the front, a trough will linger over 
the eastern Great Lakes and Upper Ohio Valley Sunday night
through Monday morning before a ridge builds in from 
the south- central United States late on Monday through midweek.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
No major changes with the ongoing forecast, with mostly clear
skies over the area ahead of system to impact us tomorrow.

Original discussion...
The first half of this weekend has been very nice with 
beautiful fall weather on this last day of October, but big
changes are coming for the first day of November. A warm front
will advance northward through the Upper Ohio Valley and eastern
Great Lakes this evening. Temperatures will initially drop off 
after sunset this evening and then slowly rise late tonight into
the predawn hours of Sunday morning with gusty southerly winds
and warm air advection ahead of a cold front. High and mid level
clouds will increase overnight as the upper level trough digs
across the Great Lakes region.

The warmest portion of the day on Sunday will be ahead of a
strong cold front passage. This cold front will move quickly
from west to east during the morning hours on Sunday. Moisture
will be limited but the strong forcing with this system will be
enough to develop an area or line of light to brief moderate
showers along the frontal passage Sunday morning. Winds will
shift from gusty southwesterly winds up to 25 or 30 knots to the
west and eventually the west-northwest by Sunday afternoon. It
will be blustery and strong cold air advection behind the front
with gusts 30 to 35 knots. The highest wind gusts will be closer
to the lakeshore communities. We will start out around 50 
degrees before the front and then see a slow and steady fall in
temperatures down to the middle and upper 30s by Sunday
afternoon.

It will be feeling and looking like winter by Sunday evening. 
850 mb temperatures will drop to -10C to -12C over relatively 
"mild" lake water which temperatures are in the middle 50s at 
this time. The first round of lake effect snow of the season 
will develop Sunday evening through Monday morning for mainly 
for the inland primary Snowbelt areas. Forecast soundings 
indicate extreme lake induced instability with 700 to 900 J/KG 
CAPE. Lake effect snow showers will be likely for the primary 
and secondary Snowbelt areas Sunday evening with everyone seeing
flakes flying. We expect snow accumulations to start happening 
after sunset Sunday evening and as temperatures continue to 
lower into the lower 30s and upper 20s. The high- res short term
models show a few more organized LES bands trying to develop 
and also a potential fetch for a few hours coming off Lake 
Huron. Snowfall forecast may potentially be generally 1 to 2 
inches for most of the Snowbelt areas. Geauga, portions of 
Ashtabula, inland Erie County PA, and Crawford County PA could 
see 3 to 5 inches by Monday morning.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The large upper-level trough will be continue moving off to east of 
us on Monday, with a weakening trend in upper-level forcing and lake-
induced instability. Lake effect precipitation and cloud cover will 
still likely linger downstream of Lake Erie into the daytime hours 
of Monday, though a little less prevalent. Precipitation type will 
be predominantly snow, though will probability be low SLR and less 
likely to accumulate as daytime temperatures increase into the mid 
to upper 30s. Very light lake effect precipitation lingers through 
Monday night, mainly for northwest Pennsylvania as northwest flow 
and cool temperatures linger over the eastern end of Lake Erie.

Monday and Monday night are expected to be rather cool with below 
normal temperatures. However, that trend reverses as high pressure 
to our south becomes centered over the mid-Atlantic on Tuesday, 
allowing southwest winds to develop and advect warm air into the 
region. High temperatures will increase to the 50s for most by 
Tuesday afternoon.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A rather stagnant pattern is expected for the rest of the extended 
forecast as upper-level ridging and surface high pressure remains in 
control of the forecast. This will result in no precipitation 
chances, minimal cloud cover, and slightly above normal temperatures 
(highs in the 60s and lows in the 40s).

&&

.AVIATION /00Z Sunday THROUGH Thursday/...
VFR conditions at the onset of the period will deteriorate
near/after 12Z as a strong cold front moves through the region.
Reduction to MVFR conditions with SHRA expected with the frontal
passage. Ahead of the front, a strong low level jet will lead to
LLWS for a brief time until the frontal passage. Strong west to
northwest winds gusting to 30 to 35 kts expected behind the 
front, with some lake effect SHRASN possible at eastern 
terminals towards the end of the period. 

Outlook...Strong and gusty westerly surface winds are expected
behind the cold front on Sunday evening through the overnight. 
Periods of rain and/or snow with periods of non-VFR expected 
Sunday evening through Monday morning.

&&

.MARINE...
A warm front will lift north across Lake Erie early tonight. South 
to southwest winds behind this front will increase to 20 to 30 knots 
through the overnight period. A Small Craft Advisory is in effect 
01Z-12Z Saturday for these winds.

A cold front extending from a low near the James Bay will move east 
across Lake Erie Sunday morning. A Gale Warning is in effect from 
12Z Sunday until 12Z Monday for strong west and northwest winds of 
30-40 knots across the entirety of Lake Erie. Brief gale-force winds 
will be possible with the cold front Sunday morning but best chance 
for 35-40 knot winds will be late Sunday night between 00-09Z 
Monday. Winds brief diminish to around 20 knots on Monday before 
increase again out of the west and southwest. These winds increase 
to around 30-35 knots as high pressure builds south of the Great 
Lakes. The best chance for more gale-force winds will be 21Z Monday 
to 06Z Tuesday, mainly for the open waters of Lake Erie.

Winds diminish to less than 20 knots by mid-morning Tuesday. A ridge 
of high pressure will extend south of the area through the remainder 
of the forecast. This will result in southwest winds through the 
week varying between 10 to 20 knots.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Gale Warning from 7 AM Sunday to 7 AM EST Monday for 
     LEZ142>149-162>169.
     Small Craft Advisory until 7 AM EST Sunday for LEZ142>149.

&&

$$
SYNOPSIS...Griffin
NEAR TERM...Greenawalt/Griffin
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Greenawalt
MARINE...Saunders