Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
337 PM EST Thursday Nov 26 2015
an area of high pressure will remain over the East Coast into
Friday slowing an advancing cold front over the Great Lakes. The
front will move into the local area Friday into Saturday when it
will stall just south of the area. A low pressure system will move
into the region Monday into Tuesday.
Near term /until 6 am Friday morning/...
a pocket of Theta-E is sufficient to produce an isolated shower
over the western portion of the County Warning Area for the next few hours. This
will wane quickly into the overnight. A nice blocking pattern
developing across the Continental U.S. With Arctic high pressure over the
northern plains and another high over the southeast states.
Tonight the midlatitude and southern jets merge over the Great
Lakes. Meanwhile a low level jet out of the SW will pull in some
moisture upstream and west of the region. The models seem to be
underestimating the low level warm air advection so have adjusted
temperatures upwards slightly. Over the area the warm air
advection continues to support some good mixing with winds 15 to
20mph with gusts to 30mph. The showers should hold off until
Friday morning as the high off the East Coast slows it's forward
Short term /6 am Friday morning through Sunday night/...
Friday will start off with some light showers in the northwest as
a cold front approaches. Have tightened the pop gradient as the
eastern counties are not likely to see showers until later in the
day. In fact timing of the rainfall will be the biggest challenge
as the trend has been to continually slow the frontal passage. Have also
reduced the rainfall amounts as the best moisture
convergence/frontogenesis will be displaced to our southwest.
Precipitation type does not appear to be a concern for our area as the
cold air chases the moisture as the cold front slips south on
Saturday. The front will stall over our southern counties on
Saturday with most of the northern portions of the County Warning Area dry and
cool. The European model (ecmwf) model is slower in bringing the front south so
have continued as least some rain chances for all areas during the
first half of the day. By Sunday the front should be south of the
area with cool high pressure building over the region.
Temperatures will remain near seasonable normals as h850 temperatures
remain above freezing.
Long term /Monday through Thursday/...
there is consistency in the big picture solution for the first part
of next week this set of model runs...but less as we get to middle
week. As the southwestern upper low lifts out to the middle of the
country...surface low pressure will move across the Midwest to the
central Great Lakes. This will lift a warm front north on Monday
night bringing showers to the region. Tuesday night seems to be the
consensus for the cold front to move through. Differences though in
if and how this upper low lifts out of the region. GFS lifts it out
as jet energy crosses southern Canada while the European model (ecmwf) lingers the
upper low near Lake Erie middle week. Overall can call the forecast
mostly cloudy with a chance of rain/snow showers across NE Ohio/northwest PA
with wrap around moisture. High pressure by Thursday. Temperatures
trending warmer for Monday/Tuesday. More seasonable by middle week.
Aviation /18z Thursday through Tuesday/...
south winds will continue to gust around 25 knots periodically
through the next 24 hours. Low level wind shear a concern
especially for western sites with a strong low level jet overhead.
The low level wind shear will be maximized late tonight and early Friday morning.
VFR conditions will continue with variable middle clouds. Cold front
will be across Northwest Ohio around 18z Friday. There is some timing
differences on when the rain starts. Have aligned the non VFR
conditions with the arrival of the rain.
Outlook...non VFR developing Friday afternoon and continuing into
Saturday. Increasing chances of non VFR again Monday.
south winds will have an uptick in speeds tonight by a
few knots. This will bring winds back into the Small Craft Advisory
criteria on the east end and will leave the headline as is. Friday's
cold front is expected to reach the lake by late afternoon and be
south of the lake during the evening. Winds will abruptly shift from
the south-southwest to the north. Winds will not be exceptionally
strong behind the front and the cold air advection is minimal...but
it still will likely be enough for another Small Craft Advisory
Friday night...even if it is just GOES until Saturday morning. The
northeast flow will be predominate on the lake from Saturday through
Monday. Monday night a warm front will lift north and bring winds
around to the south. Right now the timing of the cold front is for
Marine...Small Craft Advisory until 4 PM EST Friday for lez148-149.