Scientific Forecaster Discussion
fxus61 kcle 252346
Area forecast discussion
National Weather Service Cleveland Ohio
646 PM EST Sat Feb 25 2017
high pressure over the plains will move east across the Ohio
Valley on Sunday. The high will move off the Carolina coast on
Monday. A warm front will develop in the Ohio Valley on Monday
and move north across the area Monday night. Low pressure will
develop over the plains by Monday night and move to lower
Michigan by Wednesday. A strong cold front from this low will
push east across the local area later Wednesday.
Near term /through Sunday/...
burst of snow crossing parts of northwest PA associated with the
upper trough and weak secondary cold front. That activity should
move east early tonight. It will get cold enough for lake effect
later tonight (see "original tonight discussion" below). There
appears to be a trailing short wave over the upper Midwest that
may enhance the snow a bit for a few hours during the early
morning on Sunday across extreme northeast Ohio and northwest PA
otherwise not expecting anything significant. Decided to call
the overnight snow showers outside of the snow belt "flurries".
No other changes for the early evening update.
Original "tonight" discussion... just had a call and the precip
has changed to light snow in northwest PA. Expect temps to continue to
fall and the threat for liquid precip appears over. Not many
changes to the tonight forecast as a period of lake effect is
expected downwind of the lake with the rest of the area mainly
dry. The returns on radar right now appear to be mainly flurries
or very light snow but some intensification is likely as 850 mb
temps dip to around neg 12 or 13 by morning. Moisture is very
limited and this can be seen on satellite as the clouds to the
west of here have somewhat of a diurnal appearance. BUFKIT
soundings show an inversion around 4k feet developing after
midnight with low levels drying at the same time. Will keep
likely wording going but accums should be no more than a couple
inches. Given the recent warm weather and warm ground temps most
of this accumulation should be on grassy surfaces. It will take
some time for clearing to occur overnight in the west but
confident skies should be partly cloudy over about the west
third of the area by daybreak. Guidance temps seem reasonable
and have been followed.
Short term /Sunday night through Tuesday night/...
the lake effect should quickly die down on Sunday as ridging and
low level drying win out. Warm air advection will get going
during the day and temps should climb to around normal for
highs. The warming will continue through midweek as a pair of
low pressure systems move northeast out of the plains. These
lows will eventually merge and reach lower Michigan late
Wednesday. The models are in fair agreement with this scenario
which means a period of wet weather is likely at mid week.
But...first things first. The models are also showing some warm
air advection precip on Monday. Think this is mostly overdone
for the local area with better chances just to the south. Have
gone ahead and trimmed back precip chances to the far southern
end of the area. Would be surprised to see much more than
sprinkles. Have also slowed down the precip for early Tuesday
based on the new guidance. It appears the precip will come in
waves. The first is expected on Tuesday as the first low moves
to just north of the area. There may be a brief dry period
before a more significant wave of precip arrives as the lows
merge Tuesday night into Wednesday. Will go with likely or
higher wording for Tuesday night. A half inch to inch of quantitative precipitation forecast
looks possible if the 12z guidance is correct.
Have stayed close to guidance for temps.
Long term /Wednesday through Saturday/...
models continue to track low pressure across the lower lakes on
Wednesday then tracking them into New England on Thursday. Luckily
it will be warm enough on Wednesday that all precip should fall as
rain. Behind the system more seasonal conditions return. Rain turns
to snow Wednesday night as the 850mb temps dip to -10c by daybreak
Thursday. Chance of snow continues into Friday as upper level
trough will linger across the eastern Great Lakes. High pressure
finally builds over the area again Saturday morning.
Aviation /00z Sunday through Thursday/...
upper trough still influencing the weather through most of the
night. West gusts to 30 to 35 knots still possible for the next
hour or two. Otherwise expect a slow trend downward. Mix of
lower end VFR and MVFR will continue for the next few
hours...but expecting most of the ceilings to come down into
MVFR range for the remainder of the night. Flurries outside of
the snowbelt of NE Ohio/northwest PA...where the better snow showers are
expected with west flow off of the lake. Keri may very well dip
into IFR range with the snow...but there is not timing it
without a developed band/enhanced snow. Clearing will arrive
Sunday from west to east. Surface high passes to our south and
as that backs the winds to the southwest...the snow showers will
end by mid/late afternoon for Keri and ceilings will improve
there too. A few gusts to 20 to 25 knots possible for
tol/fdy/cle/mfd for Sunday afternoon.
Outlook...areas on non-VFR Tuesday through Thursday.
west winds to 30 knots will gradually diminish overnight as
high pressure slowly builds over the lake. Winds on the west
half of the lake will diminish to 10 to 20 knots late this
evening...but the small craft on the east half of the lake will
continue into Sunday morning. Winds turn to the south Sunday
night as the high shifts east of the lake. Winds will increase
considerably on Wednesday night with the passage of a cold front
as the low moves off to the east.
Marine...Small Craft Advisory until 3 PM EST Sunday for lez146>149.
Small Craft Advisory until 4 am EST Sunday for lez142>145.