Area Forecast Discussion
Issued by NWS Cleveland, OH

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173
FXUS61 KCLE 281137
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
637 AM EST Tue Feb 28 2017

.SYNOPSIS...
A warm front will lift north through the area today, as low
pressure deepens and tracks into the Great Lakes region by
tonight. A strong cold front will push through the region
Wednesday as the low departs into southeast Canada. High
pressure will briefly build across the region Thursday before a
clipper system tracks through the southern Great Lakes Thursday
night.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Minor updates to pops and wx with this update. Showers already
being reported at KTOL this morning, so have sped up arrival of
pops across the western half of the area. Also removed thunder
mention this morning, as lightning activity has diminished
upstream and model soundings indicate little/no instability
through at least the morning hours across the area. Also trimmed
back pops early this afternoon for a few more hours of slight
chance/chance pops, holding off any likely pops until after 6
PM.

Original discussion...
Shower and thunderstorm activity over Illinois/Indiana is
expected to advect northeastward towards northwest Ohio this
morning, on the nose of a 50kt low level jet. Hi-res models
continue to indicate a weakening trend in the jet and convective
activity through 15Z, therefore will carry high chance pops at
12Z in NW Ohio slowly diminishing through 18Z as the pops spread
eastward. Went ahead and mentioned a slight chance of
thunderstorms this morning given upstream lightning activity,
although elevated instability will be weak to at best marginal
this morning.

Warm front will lift north across the area through the day, with
perhaps a break in precip across much of the forecast area.
Guidances continues to indicate a split in precip, confined to split
jet energy across the southern half of Ohio and across northern
Indiana/southern lower Michigan. However, given surface
destabilization in the warm sector will maintain chance pops through
the afternoon, with likely pops just skirting the southern part and
northwest part of the area by late afternoon. Regardless, skies
should be mostly cloudy through the day. Temps are expected to reach
the upper 50s in most locations, possible into the lower 60s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
Attention turns to severe weather potential late Tuesday night
through Wednesday morning. Strong, coupled upper jet feature across
the western Great Lakes will deepen and advect a surface low through
the central Great Lakes Wednesday. Hi-res guidance continues to
indicate thunderstorm development in the warm sector of this system
late Tuesday night just ahead of the cold front in Illinois.
Guidance indicates a potential MCS growing upscale across Indiana
late Tuesday night moving through Ohio early Wednesday morning. As
far as timing, 00/06Z guidance seems to be just a touch slower with
the potential MCS, moving it into the western part of the forecast
area around 12Z Wednesday. Potential discrete cell development ahead
of the line isn`t out of the question, especially if enough
destabilization takes place upstream.

Biggest threat for severe weather at this point is damaging winds,
especially with a linear convective system. Low level jet ramps up
to 75 knots through the area early Wednesday morning. Models are
showing impressive 0-6km bulk shear values of 80kts expected and
hinting at 500-1000j/kg of CAPE into the area, but a slower solution
would favor a bit more destabilization Wednesday morning, especially
across the southeast part of the area. Nevertheless, agree with the
latest SPC Day 1/2 outlooks placing most of the area in a slight
risk of severe weather.

Cold front will push east through the area late Wednesday, with much
colder air filtering into the region. Rain mixing/changing to snow
showers are possible Wednesday night into Thursday morning as
lagging upper trough swings east through the Great Lakes, with some
lingering lake effect during the day Thursday across favored areas
of NW PA and far NE OH, as 850mb temps drop to around -14C. A
clipper system is then expected to track east across the area
Thursday night. Differences still exist with exact track and timing,
but at this point doesn`t look to be any more than a typical 1-3"
clipper system. High pressure then builds across the region Friday
into Friday night. Again, some lingering lake effect is possible
during the day on Friday across favored areas.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
The long term begins Saturday with the GFS and ECMWF showing a
surface high over the Carolinas extending north into the Ohio
valley. Aloft a broad ridge will be to our west with northwest flow
aloft across the lakes into the region. Models do show moisture
dropping ese into the area during the day...overrunning a warm front
in the plains. For now will go with only slight chance pops given
the parent surface low moves across southern Manitoba to Ontario.
Saturday night will increase to chance pops.  Area will be in the
warm sector with the warm front north north and east. Models show
increasing moisture along with a short wave aloft approaching from
the west. Monday into Monday night looks Like the next significant
chance of precip in the area. Models show an upper trough across
south central canada with a surface low in  the western lakes or
upper midwest. Moisture will be moving into the area ahead of the
system Monday as the cold front associated with the low moves
through during the period. Temps mostly above normal.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
Radar shows light rain moving into the area from the west this
morning. Conditions are VFR with the exception of KTOL where
visibilities have been 3-4sm in the rain and fog. The rain will
continue to drift east reaching the KCLE area around 14z and
lasting for a couple hours. Expect conditions to remain a low
VFR in the rain but likely drift into the MVFR range this
afternoon with CIGS lowering. This evening conditions will
continue to lower to IFR although main concern will be
developing low level wind shear as 1800-2000 foot winds increase
to 50 to 60kts overnight. Surface winds will increase as well
gusting into the mid 20 knot range. Also after about 03z expect
an area of thunderstorms to begin moving east across the area
reaching near KCLE by 10z. Another line of thunderstorms is
expected into the west by 12z.


OUTLOOK...Non-VFR at times Wednesday in -SHRA and TSRA with
gusty winds. Non-VFR Wednesday night into Friday.

&&

.MARINE...
Low pressure over the central plains today will move northeast
across the central lakes after midnight tonight. Winds will be from
the south today ahead of the low.  Tonight winds will turn southwest
and increase to 15 to 20 knots as the low moves into the region.
Wednesday looks windy with southwest winds increasing to 30 knots
during the afternoon before turning northwest and decreasing to 20
to 25 knots behind the front wednesday evening.  Friday and saturday
high pressure builds across the lake.

&&

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

&&

$$
SYNOPSIS...DJB/Greenawalt
NEAR TERM...Greenawalt
SHORT TERM...Greenawalt
LONG TERM...TK
AVIATION...TK
MARINE...TK



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