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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
1139 PM CST Thursday Jan 29 2015

issued at 332 PM CST Thursday Jan 29 2015

A series of shortwaves have transversed the area overnight and
today. In its wake a deck of stratus was in the area and starting
to break up upstream in Minnesota. Strong winds are helping to usher in
drier air...however warmer 850 mb temperatures exist to the west over the
Dakotas...the west to northwest winds were not leading to much cooler temperatures
in our area.


Short term...(this evening through friday)
issued at 332 PM CST Thursday Jan 29 2015

Main forecast concern for the short term are the clouds tonight
and when they clear out. Once the clouds clear out...we look to
have a partly sunny day on Friday before the next weather producer
encroaches on our area.

Clouds have been tricky today...the NAM wants to keep the clouds
around overnight. Think the NAM is suffering from a moist bias in
the bl as snow depth increases across the area overnight with no
precipitation. Looking at the gfsbufr soundings...the moisture wanes and
does not seem to produce anything more that scattered clouds. Also
looking upstream...the stratus is breaking out. There are some
thin high level cirrus clouds...but think that stratus will
continue to break out. After this...partly sunny skies are likely
tomorrow before high level moisture advects in from the next
system affecting our area this weekend.

Long term...(friday night through thursday)
issued at 332 PM CST Thursday Jan 29 2015

A weekend storm will affect the area. However...additional swings
with the models regarding the storm track are expected. Thus users
should only place low to possibly moderate confidence regarding any
snow amounts this far out.

Dry conditions will be seen across the area Friday night as high
pressure moves into the Ohio Valley. Lows should average a little
below normal. Attention then turns to the approaching storm system.

Differences between the models have narrowed over the past 24 hours.
As mentioned earlier...additional swings in the storm track are
expected over the next 24-36 hours.

The models appear to be agreeing that the south half of the area has
the better chances of snowfall.

For the most part Saturday morning will be dry across the area with
increasing clouds. The Arctic front will slowly move through the
area during the day and should be south of I-80 by sunset Saturday.

A mix of rain and snow will slowly develop/spread into the southern
half of the area Saturday afternoon. By sunset...mixed precipitation
should be falling south of I-80.

Saturday night the strongest forcing moves across the area and any
mixed precipitation will change over to all snow by middle evening.
Cold dry air moving in behind the Arctic front may initially delay
the start of the snow across the north half but snow will
develop/spread over the entire area prior to sunrise. The
increasingly colder air moving into the area means that snow/rain
ratios will be increasing late Saturday night and into Sunday

Snow will be widespread across the area on Sunday with snow
decreasing in overall intensity and slowly ending from west to east
Sunday afternoon.

This winter storm will be a headline event. We will not be going
with any headlines today but headlines will probably be issued 24-36
hours from now.

Snowfall amounts will be the lowest in the Highway 20 corridor and
the highest south of an Ottumwa to Peoria line. A reasonably sharp
gradient in snowfall amounts is expected somewhere between highways
30 and 20.

Very preliminary numbers suggest 1-2 inches possible in the Highway
20 corridor with 5-6 inches possible south of an Ottumwa to Peoria

Cautionary note...these numbers will change over the next 36 hours
as the storm track becomes better refined. Users should not take
these early amounts as absolute.

Sunday night on...
lingering light snow is possible across the eastern half of the area
Sunday evening as the storm system moves toward the East Coast. As a
result the model consensus has slight chance probability of precipitation.

The model consensus has dry conditions on Monday as high pressure
quickly moves through the Midwest. Temperatures will be well below

Starting Monday night...the models are suggesting a rather active
northwest flow pattern developing with the potential for several
weak systems spaced 1 to 2 days apart.

As such the model consensus has slight chance to chance probability of precipitation in the
Monday night through Tuesday night time frame with the passage of
the first system.

Some lingering snow may continue into Wednesday as the remnants of
the first storm system exit the area. The model consensus has slight
chance probability of precipitation across the far south and eastern areas. Temperatures
will average below normal.

Wednesday night/Thursday the model consensus has dry conditions
across the area as the next high pressure moves through the Midwest.
Temperatures will continue to average below normal.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 1134 PM CST Thursday Jan 29 2015

MVFR clouds will continue to clear out overnight with a diminishing
northwest wind. VFR conditions will continue through rest of taf period.


Dvn watches/warnings/advisories...


short term...Gibbs
long term...08
aviation...rp Kinney

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