Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
1256 PM EST Friday Dec 13 2013
high pressure situated along the Ohio River will shift to the East
Coast today. Low pressure from the Southern Plains will move up
the Ohio Valley on Saturday and shift to the East Coast by early
Sunday. High pressure is expected to build south out of Canada on
Near term /until 6 PM this evening/...
only minor changes made to maximum temperature for this afternoon and
pop values over northwest PA. Expected snow showers to persist
over northwest PA through the afternoon and they may increase over
Erie County near the town of northeast as the Lake Ontario and
Erie snow bands merge and sag southward. Boundary layer instability
has decreased as the inversion height has lowered. Will continue
the mention of a couple inches of snow. A maximum afternoon
temperature in the 25 to 30 degree range is expected for most
Short term /6 PM this evening through Sunday night/...
models remain fairly consistent handling the low moving up the Ohio
Valley tonight and Saturday. Confidence is fairly high today. Quantitative precipitation forecast
amounts are up a little with the new 00z runs with much of area now
prognosticated to get around 0.50 inches liquid equivalent. With snow to
water ratios dipping to around 10 to 1 on Saturday expect most of
the area to get between 5 and 6 inches of snow. This is consistent
with the earlier thinking of 4 to 6 inches. Have gone ahead and
hoisted a Winter Weather Advisory for the entire area. The precipitation
will arrive in the west this evening and will start the headline a
little sooner there. By 06z Sunday most of the snow should be gone.
The scenario the next 36 hours is a classic setup for good snow
across the area with an inverted trough sliding east across the
region. The Gulf should open and expecting good isentropic lift.
Some moderate to heavy snow could occur on Saturday morning for a
few hours. Some banding is likely as strong low level convergence is
likely somewhere across the forecast area. Locations under this
preferred area could see locally higher snow amounts. Unfortunately
right now it is tough to tell where and if this will occur. Later
shifts may need to upgrade a row of counties to a warning at some
point. Other concern today is possibility of mixed precipitation Saturday
afternoon in the far south. The southern end of our area should be
close to the transition zone. The worst case scenario would be a
period of sleet falling on top of snow in the Millersburg...Canton
and Youngstown areas. For now will continue with all snow but this
too will need to be watched.
Some lake effect snow is likely Sunday and Sunday night. It does
not look like the moisture will be deep enough to sustain accums
high enough for more headlines. After getting close to freezing on
Saturday...temperatures will again plummet. Have used a blend of guidance
Long term /Monday through Thursday/...
temperatures will start off cold on Monday as the last push of the latest
round of Arctic air will still be over the area. However...from Tuesday
on...temperatures should moderate back closer to normal as the upper trough
lifts north of the area for a while. Weak fronts moving through the
area will keep a threat for shsn going Monday and Tuesday but by Wednesday high
pressure pushing up the Ohio Valley may be able to end the shsn but
for now will keep a small chance going since warm advection lift and
decent deep moisture present.
The models differ so much by Thursday its anybody's guess as to what may
be happening although in general it appears a low will be developing
in the south Central Plains area and heading NE toward the upper
lakes late Thursday into early Friday. Models tending to keep precipitation west of
area on Thursday so forecast of starting chance probability of precipitation by Thursday night seems a
reasonable way to go.
Aviation /18z Friday through Tuesday/...
some lake effect snow will continue to clip the Erie area through
the evening. Elsewhere expect to see VFR conditions through the
We will then monitor the movement of low pressure that will
develop over the Southern Plains. This low will move toward the
Ohio River valley by sunrise tomorrow. Expected to see MVFR
ceilings and visibilities advect into the area from the
southwest. It will take a little bit of time to overcome the dry
air at the lower levels but when the snow begins it may quickly become
moderate. Current thinking brings some light snow after midnight
across the west then gradually spread it eastward. As the low
tracks across southern Ohio it will bring moderate snowfall and
IFR/LIFR conditions. This moderate snow will begin around 09z
across the west...11z central and by 13z across the east. Total
snow accumulations at most locations will be in the 4 to 7 inch
range through Sunday morning.
Outlook...non VFR conditions will continue on Saturday afternoon with
widespread accumulating snow. Non VFR will linger across NE Ohio/northwest
PA through Tuesday.
winds and waves should diminish enough this morning to allow Small Craft Advisory on
west part of the lake to end by 15z while east will need to run
until 21z. Low still expected to track NE to near eri by late Sat
night then shift to middle Atlantic coast by midday sun. This creates
developing NE wind scenario on the lake but stronger winds and
higher waves stay north of the nearshore waters so may not need a
Small Craft Advisory for this on Sat. Sat night winds back to west and increase to 15
to 25 knots so Small Craft Advisory will be put up. Winds will then waver back and
forth mainly from a SW direction through Tuesday with Small Craft Advisory conditions likely
Ohio...Winter Weather Advisory from midnight tonight to 10 PM EST
Saturday for ohz010>014-020>023-031>033-038-089.
Winter Weather Advisory from 9 PM this evening to 7 PM EST
Saturday for ohz003-006>009-017>019-027>030-036-037-047.
PA...Winter Weather Advisory from midnight tonight to 10 PM EST
Saturday for paz001>003.
Marine...Small Craft Advisory until 4 PM EST this afternoon for