Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
1254 PM EST Monday Dec 22 2014
a ridge along the East Coast will move east today. Low pressure
will track out of the plains on Tuesday and lift a warm front
north across the area. Another area of low pressure will track
north from the Gulf Coast on Tuesday and pull a cold front across
the area Wednesday night.
Near term /until 6 PM this evening/...
lead area of stratus has been eroding as it lifts north across
Ohio allowing some breaks in the clouds to develop again. Middle and
high clouds will continue to spread northeast and the trend
through the afternoon will be for clouds to fill in. Adjusted
cloud cover and tweaked high temperatures up a degree or two along
the Lakeshore from Cleveland to Erie where downsloping has helped
temperatures warm to near 40 degrees already.
Precipitation has blossomed across Illinois where moisture can be
seen streaming north on water vapor imagery. This will approach
Northwest Ohio ahead of the upper level trough that will pivot
northeast towards Chicago tonight. Nudged probability of precipitation up to 90-100
percent in a few of the western counties as those areas should
see at least a period of rain overnight.
Original discussion...a warm front will be developing over the
Ohio Valley today and it will move slowly north. Some sunshine
this morning especially over the northern third of the area. The
clouds are moving in from the south a few hours quicker than
expected. Adjusted the sky cover to indicate this with becoming
mostly cloudy south and becoming mostly cloudy in the north this
afternoon. Because of this quicker increase in sky cover adjusted
the highs down a few degrees especially at well inland locations.
Short term /6 PM this evening through Thursday night/...
for this period the weather is wet with above normal temperatures
and becoming windy and then cooling off.
A warm front will be moving up tonight with some rain. The question
is how far east will it spread. At this time spread the likely probability of precipitation
into extreme NE Ohio based on rain typically spreading quick with a warm
front and most of the models spread it east. The next shifts will
have to monitor this to see if they need to increase the probability of precipitation and
even spread it further east.
On Tuesday several of models the GFS and Canadian have a dry slot
developing in the afternoon. This is the first model run that this
is being forecast. Leaned that direction but still kept the probability of precipitation
likely or higher until the trends are clearer.
The model trends have a low moving up from the Gulf Coast states
Wednesday and then moves the low through Michigan Wednesday
evening and then into Ontario by Thursday morning. Another wave of
rain will move up on Wednesday and then it will become more
showery as the front moves through. Did not mention thunder but
this threat will have to be monitored. The rain showers will
change to snow showers late Wednesday night...not expecting that
much snow mainly 2 inches or less. Some snow showers will linger
Christmas morning especially in the east.
The wind will be the big issue late Wednesday into Thursday. The
winds aloft are fairly strong...45 to 50 knots at around 2000 feet
above the ground but the cold advection is not real strong. So the
question is how much of the wind will mix down. The Wind Advisory
definitely looks reasonable. A high wind watch may also be needed
eventually. At this time it seems like the strongest winds near
55 and 58 miles per hour if they occur would be brief...gusts to 50 miles per hour would
be more common.
Rainfall amounts from tonight through Wednesday night will range
from an inch and a half west to just under an inch east. Since the
rain will be spread out over several days not expecting widespread
flooding. Water levels will rise in streams and creeks but they
will remain below bankfull. Some ponding of water on roads may
occur since the ground is saturated.
The temperature forecast is a little tough. The guidance lows for
tonight and Tuesday night seem too low based on clouds and some
wind. Went toward the warm guidance on Wednesday with the low moving
up from the south and bringing up warm air.
Long term /Friday through Sunday/...
upper level pattern trending toward a ridge that will build east
across the region Friday and to the East Coast by Saturday. Another
deep digging trough will dive into the central United States by
Saturday and then dampen out by Sunday as it moves east.
European and GFS seem to be in agreement with holding back on the
precipitation Friday. Will drop probability of precipitation back a few and end the threat
for precipitation. Will gradually move the precipitation into the
region Friday night from west to east. Warm air advection should
keep the precipitation primarily rain Friday evening and then
transition over to all snow by late Friday night. As flow becomes
more favorable by Sunday...snow will develop in lake effect and be
confined to the northeast snowbelt.
Otherwise...winds should diminish across the area by Friday and then
increase again over the weekend as next storm system moves into the
Needed to bump up temperatures a few degrees due to longer potential
for warm air advection to take place early in the extended periods.
Aviation /18z Monday through Saturday/...
an area of cloud cover around 4500 feet will have several breaks
in it as it lifts northeastward east of a line from kmnn to
Sandusky. However any breaks will only last a few hours as
additional lower end VFR clouds spread into the region from
western Ohio through the evening hours. This area of cloud cover
is associated with low pressure that is moving into the western
Great Lakes but it is weakening as it moves this direction. This
makes timing of any light rain into the region difficult. At any
rate it appears the best chance of any persistent light rain will
be across Northwest Ohio near or shortly after midnight. This will
attempt to spread eastward toward sunrise but some drier air will
likely slow this down. Some MVFR ceilings and visibilities will be
common with the showers. Maybe a bit of IFR across the central and
west around sunrise. The region will then be between storm systems
with some weak lift and possible drizzle continuing through
Tuesday morning...especially across the west.
Southeast winds may become gusty toward sunrise and continue
through Tuesday morning. The stronger winds will be near and east
of a kmfd to kcle line. Gusts up to 25 knots will be
possible...especially near Keri.
Outlook...non VFR possible through Thursday.
Lake will be relatively quiet through Wednesday morning. Then as
storm system approaches the region from the southwest...winds will
increase dramatically Wednesday evening and continue into Thursday.
Possibility is that we will need small craft advisories early on
transitioning to a possible Gale Warning by Thursday morning. I dont
anticipate winds will be strong enough to support storm conditions
on the lake. Winds diminish Thursday into Friday.