Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 011147
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
647 AM EST Thu Dec 1 2016

.SYNOPSIS...
Low pressure over southern Quebec will continue to move slowly east
today.  A trough extending west from the low will remain nearly
stationary across the Great Lakes through Saturday. High pressure
will begin to build into the local area Saturday afternoon and
Saturday night.  The high will then move to the Outer Banks of North
Carolina by Sunday night. A warm front will lift northeast across
the area Sunday night.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A few sprinkles/flurries continue across the eastern portions of
the forecast area at this time. Lake effect band is developing
over Lake Erie and will continue to do so today. Rest of the area
should see fair weather but remain cloudy through the day.
Otherwise, no significant changes with this update.

Previous Discussion...

Vertically stacked low pressure is finally moving east of the
area this morning. The storm system forced a cold front through
the area last evening. A trailing trough of low pressure will
extend west over the Great Lakes through the day. The wind flow is
expected to set up a lake effect rain band up the spine of the
lake toward Buffalo. Temperatures at the surface and aloft should
keep the precipitation in the form of rain through the day today
over the lake. There is the possibility that the rain could become
mixed with or change over to light snow inland away from the lake
in brief flurries or snow showers especially this afternoon into
the evening hours.

For the rest of the area, some wrap around moisture will stream into
the area and produce some clouds through the day.  Some breaks will
develop in the afternoon.  Otherwise, not expecting any
precipitation across areas away from northeast Ohio and northwest
Pennsylvania.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
Surface trough will continue across the forecast area tonight into
Saturday night.  This should keep the mean flow supporting some form
of lake effect precipitation.  Eventually, cold air wraps into the
forecast area at 850 mb when temperatures drop down to -6 C.  This
supports conditional instability across northeast Ohio and northwest
Pennsylvania. The band of precipitation shifts to more multibanded
by Friday and especially Friday night.  Surface temperatures will
drop below the freezing mark and should support snow inland in the
northeast.  The question is how much snow we will get.  There is the
possibility that we could see snow approaching advisory criteria
where the snow bands persist.  As for the rest of the forecast area
the weather should remain quiet through Sunday morning.  Then, a
warm front will approach the area and bring with it mostly rain
across the forecast area and possibly a mix of rain/snow in the
extreme east Sunday afternoon. Precipitation pulls out Sunday night
with the warm front.

Temperatures should see a gradual decrease as the cold air advection
takes place in the cyclonic flow around the low pressure system and
in advance of the high pressure building into the region.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
Shortwave will be exiting the region Monday with ridging building
into the area. Maintained a dry forecast for most of the area
Monday, with the exception of far northeast OH and northwest PA,
where morning precip could linger, but expect dry conditions by the
afternoon. Attention turns to southern stream low ejecting northeast
towards the region Monday night into Tuesday. This low will open and
shear out over the eastern Great Lakes, but not before bringing at
least chance pops to the area Tuesday and Tuesday night. Both the
ECMWF and GFS are in fairly good agreement with timing of precip
onset Tuesday, so tried to time arrival of pops to these solutions.
Temperatures will be trending upward through this period with the
broad eastern CONUS ridging and return flow, and expecting slightly
above normal temps through at least Wednesday.

A pattern change at the end of the extended period is the next
feature to watch. Strong upper jet will round the base of a western
CONUS trough Tuesday into Wednesday. The ECMWF is much more
amplified with the upper level pattern, whereas the GFS is more
progressive. Regardless, both solutions usher in a strong cold front
in the Wednesday night to Thursday time frame, with an arctic airmass
(850mb temps from -15C to -18C) overspreading the area by the end of
the week. The differences between the faster fropa in the GFS and
the stronger Upper Midwest cyclogenesis and slower fropa in the
ECMWF of about 12 to 18 hours lend to a tricky pop/temp forecast
Wednesday night, and eventually beyond the forecast period into
Thursday. For now, went with a compromise for timing of fropa, and
resulting blend of low temps and chance pops Wednesday night.

&&

.AVIATION /12Z Thursday THROUGH Monday/...
West southwest winds gusting to 25 knots will affect terminals
through at least the first half of the TAF period as surface
cyclone spins across southwest Quebec. MVFR ceilings expected to
overspread the terminals through the day as trough swing through
the broad cyclonic flow over the southern Great Lakes. Some light
precip is possible, but no mention in TAFs outside of KERI due as
an precip should remain light and no affect to visibility. Some
lake effect rain/snow could affect KERI later today/tonight, but
confidence in coverage/placement of precip precludes anything
more than VCSH mention at this time.

OUTLOOK...Non-VFR likely to continue into Friday....Lake effect
snow is possible across the snowbelt east of Cle Thursday night
into Saturday.

&&

.MARINE...
Surface low over southwest Quebec will slowly spin and remain nearly
stationary through this evening, before translating eastward towards
Nova Scotia. This will keep persistent southwest flow across the
lake through this evening. Winds have peaked in the wake of the cold
front in the 25-30 kt range overnight into early this morning.
Expecting a bit of a lull in the 20-25 kt range through the morning
hours, but again expecting winds in the 25-30 kt range this
afternoon. Not expecting any gales at the time. Winds will veer a
little more westerly overnight and begin to subside a bit, but will
pick back up on Friday across the eastern half in the 20-25 kt
range. Winds will finally decrease Friday night through Saturday as
high pressure builds across the Great Lakes.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 10 AM EST Saturday for LEZ145>149.
     Small Craft Advisory until 10 AM EST Friday for LEZ142>144.

&&

$$
SYNOPSIS...Lombardy
NEAR TERM...Lombardy
SHORT TERM...Lombardy
LONG TERM...Greenawalt
AVIATION...Greenawalt
MARINE...Greenawalt


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