Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
341 am EST Wednesday Dec 11 2013
a cold front will sag south across the local area today. Arctic
high pressure will build back across the Ohio Valley by Friday.
Low pressure will track up the Ohio Valley Friday night and
Near term /through tonight/...
no changes to the headlines this morning. It appears that it will
be a marginal event for most of the advisory and warning areas.
Radar only showing some weak returns at the moment but suspect
that a couple to a few inches of snow has fallen over northwest PA
overnight. A cold front is expected to sag south across the region
today. Expect the flow to briefly become a little more SW which
will push the Main Lake effect activity up the lake. As the flow
becomes northwest this afternoon expect the snow showers to get back into
the headlined areas. There will be a brief window of good moisture
this afternoon and evening but big time drying occurs overnight.
Do not know if there will be enough time for the lake effect to
get set up before the drier air begins to move in. Instability is
OK today and diminishing winds will improve residence time. Suspect
that a few townships along and just south of I-90 in eastern Erie
County will bear the brunt of the snow. The southern half of the
advisory area will likely see no more than an inch or two. Further
west and south some light snow is likely today as the front moves
in. General accumulations should range from around an inch along
the Ohio Turnpike to no more than a dusting south of the U.S.
Route 30 corridor. Have sped up the onset of the snow by a couple
of hours from the previous forecast. Temperatures will struggle today as
clouds will arrive just after the coldest part of the day. Expect
readings to be a few degrees cooler than Tuesday. Some clearing is
likely in the west tonight which will allow for the coldest night
of the year with single digit lows in many areas.
Short term /Thursday through Saturday night/...
some lake effect showers will continue in far NE Ohio and northwest PA on
Thursday but accums are expected to be light. Forecast soundings
showing the inversion lowering to around 5k feet during the day.
Will go with local accums. It will remain very cold with highs
struggling to get out of the teens. Thursday night and Friday will
be dry. The big story during the period will be the low moving up
the Ohio Valley for the weekend. The 00z models continue to be
similar to previous runs...albeit a tad faster. Have ramped precipitation
chances up Friday night. The 00z European model (ecmwf) is a little cooler than
earlier runs while the GFS continues to hint at some mixed precipitation
in the far southeast corner of the area. Not sure what to make of these
differences but the colder European model (ecmwf) solution seems reasonable given
the cold air mass the lows is trying to displace. It certainly
looks like headlines will be needed for the system as a general
snow is expected. The snow should end from west to east Saturday
night. Suspect that much of the area could see 4 to 6 inches of
snow by that time.
Long term /Sunday through Tuesday/...
low pressure is prognosticated to move southeast into the Delta Region of
the Gulf Coast states and then track northeast along the Appalachian
Mountains into the Ohio Valley. Secondary low will develop along the
East Coast and become the dominant low by Saturday night and then
exit off to the northeast.
Cold air advection will take place across the forecast area over the
weekend and due to the storm system developing on the coast...this
will make it more difficult for the warmer air from the Atlantic to
get into the forecast area. Latest guidance suggests thickness
values at 1000 to 850 mb should be cold enough for snow along with
850 mb temperatures remaining well below 0. Therefore...at this
time...precipitation should remain all snow Sunday.
Low pressure is prognosticated to move southeast into the Great Lakes
region and bring with it a reinforcing surge of cold air and a
series of troughs through Tuesday. This will likely keep a chance of
snow going each day except on Monday in the west and south as high
pressure moves quickly east across the area.
Upper level polar jet still remains south of the forecast area
through this period allowing for reinforcing cold air shots to the
region. Little improvement in the temperature department expected as
cold air advection continues.
Aviation /08z Wednesday through Sunday/...
Lake effect snow showers continue...although in a bit of a
disorganized fashion for a time tonight over the lake and into NE
Ohio/northwest PA. Toward morning expect better organization and a band to
be in the vicinity of Erie.
A trough/cold front crosses Wednesday afternoon. Light snow should
overspread much of the area with its passage during the daylight
hours. Again the heaviest snow will be at eri with additional lake
enhancement...but IFR conditions possible at times elsewhere.
Winds will shift behind this front to the west. There is a lot of
drying behind the front with an Arctic airmass. So begin to
scatter out the ceilings toward 06z Thursday across the West. Lake
effect to continue for far NE Ohio/northwest PA through the end of the taf
Outlook...non VFR conditions will linger at times through Thursday
in -shsn...mainly over NE Ohio/northwest PA. Non VFR conditions overspread
the area again on Saturday.
active weather pattern expected on the lake through the next several
periods as fast moving systems move southeast and east across the
Great Lakes region.
Winds have diminished below gales at this time so will be dropping
the Gale Warning on the lake. However...winds remain strong enough
to support Small Craft Advisory conditions on the lake and will
hoist the advisory. Ending time does not appear to be in sight as
the lake remains rather windy through the next several periods. Will
take it out through Friday for now but will likely need to be
Ohio...Lake effect Snow Advisory until 4 am EST Thursday for ohz089.
Lake effect Snow Advisory until 4 am EST Thursday for ohz014.
PA...lake effect snow warning until 4 am EST Thursday for paz001-
Lake effect Snow Advisory until 4 am EST Thursday for paz003.
Marine...Small Craft Advisory until 7 PM EST Thursday for lez142>149.