Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Cleveland Ohio
938 am EDT Sat Apr 19 2014

Synopsis...
a Canadian high pressure system will move southeast across the Great
Lakes this weekend...then move off the New England coast Sunday
night. This will allow a low pressure system to move across the
lower Great Lakes Monday night...dragging another cold front
across the area.

&&

Near term /until 6 PM this evening/...
just made some minor changes to the forecast. The airmass if
fairly dry...however...some cumulus will develop in the northeast
flow...it should not become that widespread...mostly sunny will
handle it. The high temperature forecast looks good...no change at
this time.

Original discussion...
today will be mostly sunny and dry...albeit cooler than yesterday.
The large Canadian high centered south of James Bay will slide
slowly southeast across the Great Lakes today. As it does the the
cirrus shield from the deep south will gradually shift east. With
850mb temperatures of 2-6c not cold enough for lake effect clouds.
However...with a northeast flow off the lake it will considerably
colder along the Lakeshore than further inland.

&&

Short term /6 PM this evening through Tuesday night/...
the Canadian high pressure system will be the dominant feature
through Monday. This will produce dry weather through the period
with a gradual warm up as the high shifts east and the flow turn to
the south. Above normal temperatures expected for Easter. For Sunday the
NAM continues to be warmer than the GFS and the European model (ecmwf). Leaned
toward the warmer NAM...but cut temperatures a degree or two. The warm up
will be short lived however. Models are coming into much better
agreement on the timing of the next system. Models continue to
move a low pressure system across the lower lakes Monday
night...dragging another cold front across the area. The GFS is
slightly faster than the NAM and the European model (ecmwf) so for now will just go
likely probability of precipitation across the entire area Monday night. Expect some
lingering showers in the east on Tuesday.

&&

Long term /Wednesday through Friday/...
all of the models bring a trailing short wave into the long wave
trough early Wednesday. With the high pressure still to the west
there is a decent chance for a few more showers...mainly across NE
Ohio/northwest PA. Temperatures are tricky...if it were to stay cloudy and
showery all day then it could be chilly. Considered mentioning snow
showers in the forecast since the 850 mb temperature is prognosticated to drop to
-4c but the boundary layer will probably stay warm enough for rain
showers.

High pressure will build across the area Wednesday night but
relatively strong warm advection will be underway across the upper
Midwest. Some warm advection clouds will spread across the area by
Thursday morning and cannot rule out a shower although the odds
would favor a dry day with moderating temperatures.

Not a lot of confidence on the timing of the next front yet...
probably some time on Friday. There could be two fronts or a
prefrontal trough. Will have a chance of showers and will keep the
temperatures mild on Friday since it appears the colder air will
hang back and not arrive until Friday night.

&&

Aviation /12z Saturday through Wednesday/...
subsidence should increase this morning as high pressure builds in
from the north. VFR with a few patches of stratocumulus this
morning then patchy high clouds. The east to northeast wind will
be a bit gusty at times today. VFR continues into Sunday.

Outlook...non VFR is possible Monday night into Tuesday.

&&

Marine...
cold advection and pressure rises combined with the northeast wind
will make the west half of the lake choppy today...especially this
morning. Just enough northeast fetch and gradient this morning that
we will need a Small Craft Advisory to start the day. Winds should
slowly diminish today and I am guessing that by 10 am we can get the
wind and waves just under Small Craft Advisory criteria.

High pressure will build over the lake by this evening and the wind
will diminish quickly. Winds will veer more from the southeast
tonight ito Sunday. The gradient will be weak enough Sunday for a
lake breeze in most areas. The south gradient will be stronger by
Sunday night into Monday ahead of the next cold front but the wind
and waves will likely not pick up on the lake until after the cold
frontal passage early Tuesday.

&&

Cle watches/warnings/advisories...
Ohio...none.
PA...none.
Marine...none.

&&

$$
Synopsis...djb
near term...djb/kieltyka
short term...djb
long term...kosarik
aviation...kosarik
marine...kosarik