Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 062342
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
642 PM EST Tue Dec 6 2016

.SYNOPSIS...
An area of low pressure over the region will weaken as it moves
east overnight with a weak cold front trailing it. High pressure
will build in behind the cold front bringing dry and cooler
conditions for Wednesday. An upper level trough will move north of
the region with some much colder air expected Thursday. This will
generate lake effect snowfall into Saturday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Forecast on track and no significant changes were made with this
early evening update. Main area of rain is exiting. There is some
drizzle from Lorain eastward. Winds will be picking up from the
west during the rest of the evening and continuing
overnight...making it feel even colder.

Previous discussion follows...
An area of low pressure over southern Ohio will continue
northeast tonight. Rain will continue along and ahead of the track
of the center of the low this evening. Rain has already cleared
the I-75 corridor and will continue to clear from west to east.
Rain will linger a bit longer in NW PA with some areas potentially
seeing some mix of rain and snow after midnight in the highest
hills. Otherwise, behind the rain, winds will shift to the west
and some colder air will advect into the region. Could see some
breaks in the clouds to the west and the temperatures out there
could dip the lowest into the mid 20s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
Wednesday will be fair weather with high pressure over the region.
Attention then turns to the lake effect snow event taking shape
for Thursday through Friday Night. Cold air advection will kick in
Thursday resulting in steady if not cooling temperatures during
the day with wind chills in the teens. The H850 temperatures will
plummet from the +4C of today to -12 to -14 C by Thursday
afternoon yielding very high delta t over the lake. In the DGZ
there is deep low level moisture along with respectable omega
values for a measurable lake effect snow event. At this time the
greatest potential for accumulating snow looks to start Thursday
afternoon through Friday Night. Instability increases along with
upper level support for some convective thunder possible Thursday
Night. The flow direction will fluctuate from a WSW, to W, NW, and
then back to WSW at which point the event will lift out of the
area Saturday morning. A lake effect snow watch has been issued
for Thursday morning through Saturday morning. Inversion heights
will be favorable and quite high Thursday night at around 9-11 kft
agl before lowering to around 5-7 kft agl Saturday. The overall
conditions favor several snowbelt areas receiving over 6" with the
potential for over a foot in the higher terrain of NW PA.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Lake effect snow will be ending at some point on Saturday as
southwesterly winds shift any remaining bands back up the lakeshore
into Western NY. There should then be a brief lull in precipitation
Saturday night before the arrival of the next system. The GFS and
ECMWF have come into better agreement with regards to the initial
onset of precipitation beginning Sunday afternoon, but they still
differ significantly with how long the precipitation will stick
around. The ECMWF brings up an area of low pressure behind the cold
front Sunday night into Monday with plenty of moisture, while the
GFS is much more progressive. The precipitation type Sunday is
trending more towards mostly snow, though a mix with or even change
over to rain at some point Sunday afternoon cannot be ruled out,
especially across the southwestern portion of the CWA. Overall,
confidence remains low with regard to the timing of this storm
system. The exact timing will have an impact on the precipitation
type, so confidence with regards to that is also low. Yet another
storm may affect the region Tuesday.

&&

.AVIATION /00Z Wednesday THROUGH Sunday/...
The rain is about gone but lot`s of low cigs left behind. MVFR
cigs have moved into western Ohio and should reach the western
taf sites in an hour or two. Further east the IFR conditions will
likely persist till aft 06z except at CLE and ERI where
downsloping winds should lift the cigs to MVFR. Will try to make
all locations VFR by mid morning on Wednesday but that may be a
little optimistic. Winds will become westerly behind the front
moving across the area. Expect speeds to pick up this evening with
gusts in the 20 to 25 knot range for much of the night.

OUTLOOK...Lake Effect snow develops Thursday into Friday with
non-VFR expected, especially across NE OH/NW PA.

&&

.MARINE...
Southeasterly winds this evening will shift around to the west
overnight. Before winds shift around to the west, there will be
strong enough downslope winds to around 20 knots off the Erie lake
shore, so will start the Small Craft Advisory in this area at 00Z.
Farther west, the westerly winds will increase to 20 to 25 knots by
03Z, so the Small Craft Advisory goes into effect at that time for
the rest of Lake Erie. The Small Craft Advisory will continue
through 12Z Friday for the western basin, and until 00Z Saturday
elsewhere. There will likely be a little lull in the winds Wednesday
night and they may fall below Small Craft Advisory conditions for a
time, but will pick back up to 20 to 25 knots again by Thursday
morning, so just went with a continuous advisory.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Lake Effect Snow Watch from Thursday morning through Saturday
     morning for OHZ012>014-089.
PA...Lake Effect Snow Watch from Thursday morning through Saturday
     morning for PAZ001>003.
MARINE...Small Craft Advisory until 7 PM EST Friday for LEZ148-149.
     Small Craft Advisory from 10 PM this evening to 7 AM EST
     Friday for LEZ142>144.
     Small Craft Advisory from 10 PM this evening to 7 PM EST
     Friday for LEZ145>147.

&&

$$
SYNOPSIS...Jamison
NEAR TERM...Oudeman/Sefcovic
SHORT TERM...Jamison
LONG TERM...Mottice
AVIATION...Kubina
MARINE...Mottice



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