Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 161410

Area Forecast Discussion
National Weather Service Cleveland OH
1010 AM EDT Wed Aug 16 2017

High pressure will build east across the Great Lakes region today. A
warm front will lift north toward the region tonight, lifting
through the area on Thursday as low pressure deepens and tracks into
the Great Lakes. A cold front will push east through the region on
Friday, with high pressure building in behind the front through the


Forecast remains on track for today. Surface obs show a weak
area of convergence extending from near Dayton to Columbus where
the washed out front has stalled. Will keep a low pop in the
southern counties for this afternoon as this boundary starts to
lift back north.

Original discussion...
Surface high pressure will dominate the area today, with little
weather concerns through early afternoon across the area, aside from
some early morning patchy fog. Expanded slight chance pops across
the southwest CWA a bit this afternoon, as guidance continues to
indicated isolated convection focused along a 925mb theta-e
gradient. Went a couple degrees warmer with highs today compared to
previous forecast, in line with the warmest MOS guidance.

Surface warm front near the Ohio River will lift north toward the
area tonight, as upper trough/cutoff low and attendant deepening
surface cyclone over the northern Plains tracks east towards the
Great Lakes. Precip chances will slowly increase from the west
tonight as low level jet inches towards the region and pieces of
energy eject east/northeast out of the upstream trough. Have slowed
the arrival of pops from previous forecast considerably, with chance
pops not arriving across the western part of the area until 09Z.
This may need to be slowed even further over the next forecast cycle,
with most of the area possibly remaining dry through 12Z Thursday.

Pops will increase through the day Thursday as the warm front lifts
north through the area and the low tracks into the western Lakes.
Again, have slowed down the pop trend from previous forecast, with
likely pops not arriving until 15-18Z west, and expanding across the
entire area by 22-00Z. Models have trended a little deeper/slower
with the low and the attendant cold front, so the forecast may be
too fast yet. Dewpoints will surge into the low 70s in the warm
sector Thursday, with highs in the mid 80s. 1000-2500 j/kg of SBCAPE
possible across the area, with deep layer bulk shear 35-40 kts may
be enough to sustain organized convection late in the afternoon with
damaging wind gusts the primary threat. Instability is likely
overdone a bit in the models, with convective debris limiting
overall isolation. Concur with the SPC Day 2 outlook with a
widespread marginal risk.


Most of the models show what is essentially a dry slot sweeping
across the lower Great Lakes Thursday night with increasingly dry
air aloft and some subsidence. Will start out with "likely" pops
Thursday evening and then lower the forecast probabilities from west
to east Thursday night. The front will arrive late, probably early
Friday morning, and cannot rule out enough low level convergence and
upward motion to generate a scattered to broken line of showers or
thunderstorms but it does not appear worthy of more than a "slight
chance/chance" pop Friday, mainly in the morning.

The models have been consistent with a nice trailing short wave on
Saturday. The better upward motion and precipitation will gravitate
toward the better instability which will be well south of the area
but the actual short wave may track across the lower Great Lakes and
there would seem to be at least a chance or slight chance of a
shower or perhaps a thunderstorm. The warm waters of Lake Erie could
contribute some instability. Not sure whether Saturday may end up
being mostly cloudy or partly cloudy. Will forecast high
temperatures near guidance from the mid 70s to around 80.


The pattern will become more amplified next week. Surface high
pressure should build across the Great Lakes by Sunday and heights
will rebound. The air mass will warm above normal early next week
ahead of the next cold front which looks on track for sometime later


.AVIATION /12Z Wednesday THROUGH Sunday/...
High pressure will build across the Great Lakes today. MVFR BR,
and perhaps a localized brief IFR reduction, this morning will
quickly lift by 13-14Z. Scattered cu expected during the day,
otherwise little sensible weather concerns through most of the
period. Clouds will increase, and perhaps precip chances, by the
end of the period as low pressure moves into the Great Lakes.
Winds will generally be light through the day, with a bit of a
ENE-N lake breeze affecting KERI/KTOL/KCLE with some stronger
6-9 kt winds. Winds will veer around to the east southeast by
the end of the period.

OUTLOOK...Areas of Non-VFR possible Thursday through Thursday
night with scattered storms.


High pressure will slide across Ontario and Quebec today and
the flow on the lake will remain northeast veering more easterly
by tonight. As pressure falls to the west, the winds will pick
up on the lake also enhanced by the onshore component this
afternoon. Winds and waves will stay below small craft criteria
but the lake will get a but choppy by late this afternoon and
tonight, especially the west half of the lake.

A deepening low pressure system will track across the northern Great
Lakes Thursday into Friday. A warm font will cross Lake Erie o
Thursday followed by a cold front Friday morning. The wind field
will increase with this system as well as the threat for showers and
thunderstorms. The southwest flow will become west and northwest on
Friday and a small craft advisory may be needed. High pressure will
quickly build east across the Great Lakes this weekend and winds and
waves will settle down.




NEAR TERM...KEC/Greenawalt
SHORT TERM...Kosarik
LONG TERM...Kosarik
MARINE...Kosarik is the U.S. government's official web portal to all federal, state and local government web resources and services.