Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
323 PM EST Friday Nov 28 2014
high pressure over the Ohio Valley will move to the East Coast on
Saturday. A warm front will lift northeast across the area Saturday
as a low pressure system moves northeast across Lake Superior. A
cold front will move east across the area Sunday night. High
pressure will build east across the Great Lakes Monday and Tuesday.
Near term /until 6 am Saturday morning/...
a couple fast moving positive vorticity maximums will slide
southeast across the Great Lakes region and graze the area. These
features will spread a chance of some light snow into the area this
afternoon and evening. Best shot of moisture and upper level support
arrives around 06z this evening and continues through the rest of
the night. Snowfall should be light and confined to the northeast
half of the forecast area. Some lake enhancement may take place in
the eastern portions of the forecast area as moisture moves across
the Great Lakes. Snow accumulations in the east should be an inch or
less and none in the southwest.
As high pressure at the surface pushes east...wind flow starts to
push around to the south and this will bring a return southerly flow
to the area. Temperatures will likely not drop much this evening and
then begin to rise overnight and toward morning.
Short term /6 am Saturday morning through Monday night/...
an upper level trough will dig into the northern United States
Saturday through Monday. This feature will move primarily across the
southern tier of Canada and extend the trough into the Great Lakes
by Monday afternoon.
High pressure will move east from the Ohio Valley to the East Coast
by Saturday afternoon. The high will sit on the coast and pump warm
air back into the forecast area Saturday and Sunday. The true
effects of the warm air advection will be felt on Sunday when the
strongest warm air arrives. Low pressure will help to force the
warming into the region as it moves northeast to near James Bay. The
storm system will force a cold front east to the western portions of
the area Sunday afternoon as a weak wave of low pressure moves
northeast along the front. Front then moves east across the area
Sunday night. More showers will return with the frontal passage.
Moisture appears it will be on the light side since there will not
be a strong influx of Gulf moisture into the region.
Surface high pressure builds east into the area from the west on
Monday and will become the dominant weather feature into Monday.
Flow and cold air advection is not favorable for lake effect
precipitation so will not mention it at this time.
Cold air advection Sunday night into Monday is not that strong and
actually keeping temperatures in the middle 30s to lower 40s for
highs on Monday.
Long term /Tuesday through Friday/...
high pressure will be east of the region by Tuesday with a warm
advection pattern once again setting up for Tuesday night into
Wednesday. The amount of moisture available to lift is in question
but this time of year it always seems to produce light snow or rain
showers with each passing upper level trough. Models are slightly
different with the evolution of the upper level flow beyond
Wednesday. The GFS currently having a piece of jet energy in the
southern jet stream. The European model (ecmwf) eventually develops this feature but
it is 24 to 36 hours slower. Have continued the slight chance to
chance probability of precipitation through Thursday but confidence is low.
Temperatures through the long term will remain near to slightly
below seasonal averages.
Aviation /18z Friday through Wednesday/...
still a few light lake effect snow showers/flurries northeast of a kcle
to kyng line. These will gradually decrease through the afternoon
as high pressure shifts winds around to the southwest and eventually
to the south. There will be a lull in the activity until the warm
advection increases over the area late this evening into the
overnight hours. The chances of some light snow will increase
overnight but it looks light. There is a small window of time
closer to sunrise where some very light freezing drizzle will be
possible. Have placed a prob30 in the taf sites that have the best
chance of this occurring. The freezing drizzle looks to be very
light and a short duration but could cause significant issues.
There may be a few areas of MVFR cloud cover under the heaviest
returns on radar tonight into Saturday morning.
Southerly winds will increase on Saturday and may gust up to 25
knots. Some light rain showers may develop by 18z Saturday in the
Outlook...non-VFR returning Sunday into Monday in light showers
with the next front.
Ridge axis will gradually slide east of the lake tonight with a
southerly wind increasing. This should keep the larger waves beyond
5 nm through Saturday. Winds may develop enough of a southwesterly
component Saturday night into Sunday to need a Small Craft Advisory
then continue into Monday evening in the wake of a cold front that
will cross the lake. Winds will decrease and quickly come around to
an easterly direction by Tuesday morning.