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000 
FXUS61 KCLE 121125
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
625 AM EST Tue Dec 12 2017

.SYNOPSIS...
An arctic front will move across the forecast area this morning
producing falling temps and strong gusty winds. Meanwhile, lake
effect snow will develop in the snowbelt this afternoon and 
continue through Wednesday. Another clipper system will track 
across the forecast area Wednesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Low pressure system already into WRN NY with the arctic boundary
just through the Cleveland area. Snow has pretty much ended west
of MFD area. No major changes for the 630 update just tweaked
temps and hourly pops slightly.

Original discussion...
Low pressure now over PBZ will move east of the forecast area by 
daybreak.  The high temperature for the forecast period will around 
12z with falling temps through the day as the much colder air behind 
the arctic front spills over the area. By this evening the 850mb 
temps will plunge to -18c.  The heavier snow associated with the low 
will move east of the area with the low this morning.  However the 
light synoptic snow this morning will give way to Lake effect this 
afternoon.  Snow will increase this afternoon as strong upper level 
short wave swings across Eastern Lake Erie toward 18z.

No significant changes for the Winter headlines.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
By this evening lake effect will be in full swing.  By this evening 
extreme instability with Lake to 850 differential of 24 degrees and 
lake to 700 differential of 34 degrees.   Deep moisture bufkit cloud 
tops of 12k feet.  Luckily still alot of shear between 950 and 500 
mb which would point to multiple bands instead of one megaband.  

Lake effect will be winding down Wednesday afternoon, just as 
another clipper is moving into the area. Expect a widespread couple 
of inches of synoptic snow across the forecast area by Wednesday 
evening.

Low pressure will move east Thursday night. The boundary flow will 
back slowly from ESE to NNW during the night. Lake enhanced snow is 
likely as the winds come onshore and the current amounts are just 
early estimates. There could be locally higher amounts both in the 
primary snow belt and the secondary snowbelt if some good banding 
develops which is possible given the minimal shear progged and light 
to moderate winds and low level convergence. Temperatures will take 
a while but begin to drop in the early morning hours as arctic air 
begins to filter in over the snow cover. lake effect snow showers 
will continue on Thursday but shift into the primary snowbelt as 
winds become northwest. Drier air and increasing subsidence will 
limit additional amounts by Thursday afternoon. Temperatures will 
not recover much with arctic air over the snowpack. 

The next short wave is fighting rising heights with less 
convergence. Some patchy light snow could break out on Friday with 
somewhat higher amounts farther north. The forecast will be a degree 
or two below guidance given the cold start to the day and the 
virga/precipitation. Highs in the mid/upper 20s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
It will probably be just cold enough for some lake effect snow in 
the WNW flow behind the next short wave Friday night into Saturday, 
otherwise the patchy light snow should taper off. Clouds may linger 
as the baroclinic zone tightens and warm advection develops. most of 
the models show a plume of moisture spreading north as a broad 
positively tilted trough swings across the midwest and Ohio Valley 
Sunday into Monday. It may warm up enough for rain showers but will 
mention rain and snow given the overrunning and relatively weak flow 
in the lower layers.  

Heights are progged to be higher next week especially across the 
plains states but the mean long wave trough position looks to remain 
in the northeast through mid week. There seems to be a continuation 
of fast moving and relatively weak systems. Temperatures will 
recover back toward normal by mid week.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
Low pressure between FDY and MFD will track east overnight and
be east of the forecast area by daybreak. Expect widespread inch
or two as the system tracks east. Gusty NW winds will develop behind
the system with wind gusts increasing to lower 30s along the 
Eastern Lakeshore by late morning.

OUTLOOK...Lake effect snow will continue across the snowbelt, mainly 
east of CLE into Wednesday evening. Another Alberta Clipper is due 
Wed night into Thursday, bringing light snow to most Ohio terminals.

&&

.MARINE...
Winds will increase rapidly on Lake Erie this morning as low 
pressure slides east of the lake and cold arctic air pushes across 
the lake. Gales will occur on the central basin this morning with 
marginal gale conditions on the eastern basin. A trough of low 
pressure will swing across the lake early tonight reinforcing the 
gales and the strongest winds on the eastern basin will likely come 
tonight. Will extend the gale warning until 4 AM to cover this last 
push of wind. 

Winds will diminish rather quickly late tonight and especially on 
Wednesday as the next system approaches. The next surface low will 
track south of the lake and winds will veer quickly to the north by 
Thursday morning and northwest Thursday afternoon. Small craft 
advisories may be needed, especially on the western half of the 
lake. 

Another weak front will cross the lake on Friday. Winds will back to 
the southwest ahead of the front and veer northwest behind the 
front. Small craft advisories will likely be needed. The flow will 
become south to southwest over the weekend.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Winter Weather Advisory until midnight EST Wednesday night for 
     OHZ011-012-023-089.
     Lake Effect Snow Warning until midnight EST Wednesday night 
     for OHZ013-014.
PA...Winter Weather Advisory until midnight EST Wednesday night for 
     PAZ001.
     Lake Effect Snow Warning until midnight EST Wednesday night 
     for PAZ002-003.
MARINE...Small Craft Advisory until 9 AM EST Wednesday for LEZ142>144.
     Gale Warning until 4 AM EST Wednesday for LEZ145>149-165>169.

&&

$$
SYNOPSIS...DJB

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