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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
822 PM CST Sat Feb 13 2016

issued at 756 PM CST Sat Feb 13 2016

Radar echoes persist across the southwest County Warning Area and not seeing any
observation beneath reporting precipitation at least in our County Warning Area although
Centerville and Newton Iowa have reported a few flakes. Short term
signal is for continued saturation of lower levels and snow to
increase in coverage and intensity southwest County Warning Area through midnight
with continued warm/moist advection. Further northeast it will
take some time for saturation and snow to develop into northwest
Illinois per large dry wedge sampled on 00z radiosonde observation. As result... have
pushed back start time of advisory much of central and northeast
County Warning Area until 06z to 09z... and still may be a bit early yet.

Also... may see a break in the snow develop across the southwest
County Warning Area late tonight and early Sunday morning as the warm advection
Wing lifts northeast... but then should see redevelopment SW
by middle morning as the upper level shortwave approaches.

No changes to amounts at this time... and continue with going
forecast range of accums of 2 to 5 inches across much of the County Warning Area.


issued at 205 PM CST Sat Feb 13 2016

Analysis shows Pacific moisture riding over ridge in the intermountain
region and resulting in lightning in Wyoming. Remarkably...the highest
850 dewpoints in the Continental U.S. Are in Wyoming with this system. This system
on track to impact and move over the region the next 24-30 hours. The
moisture from this system is essentially all from the Pacific as the
return flow from the Gulf is cut off. Initialization shows system slightly
less on moisture and track trending further south. Upstream energy shows
continued short waves in northwest flow to impact area the next 3 to
4 days and possibly longer from the North Pacific.


Short term...(this evening through sunday)
issued at 205 PM CST Sat Feb 13 2016

Short term forecast confidence assessment...fair to good or average
to above average. Main issue in timing onset of snow and areas of
heaviest snowfall. Local tools suggest 4 to locally 5+ inches mostly
likely along a Sigourney to north of Burlington to Monmouth axis. change to advisory though trends suggest onset time may
be 2-3 hours too fast for evening shift to assess by late afternoon.
Best estimate is warm advection wind (waa) snow to overspread SW sections
between 9 PM and midnight and then spread northeast overnight. Most
lows will be early to middle evening of upper single digits to low teens
southwest with slowly rising temperatures overnight. Event lwe should
be mostly in the 15-17:1 range. Daybreak supports widespread 1 to 3
inch amount to have fallen except extreme NE sections. Southeast winds
will increase overnight to 10 to 20 kts with some minor drifting possibly
in Iowa toward daybreak.

Sunday...snow to continue most of the morning and diminishing in the
afternoon with another 1 to 2 inches SW section and 1 to 3 in the northeast
sections. Warm advection Wing forcing tool based on roughly 825 mb or
4k above ground level suggest best chance of 5+ inch amounts along and possibly south
of a Sigourney to near Burlington to Monmouth line. Winds will remain
10 to 20 kts in morning with minor drifting of snow mostly in Iowa and
snow and wind decreasing in the afternoon. Highs lower 20s northeast
to near 30 degrees far SW sections. Far northeast sections may pick
up only 2 inches or less for this snow event. Most areas should be in
the 3 inch range give or take an inch with again heaviest near Highway
34 to possible near I-80.

Long term...(sunday night through saturday)
issued at 205 PM CST Sat Feb 13 2016

The overall weather pattern will remain active next week.

Light snow will continue across the area Sunday night and slowly end
from west to east by sunrise Monday. Additional snow accumulations
should be an inch or less with a majority of the accumulation
occurring Sunday evening.

Quiet and dry conditions are expected Monday and Monday evening as
high pressure quickly moves through the Midwest. Attention then
turns to the next storm system.

Late Monday night and into Tuesday...the next clipper type system
affects the Midwest. The snow put down by the previous system will
likely play a role in where the Monday night/Tuesday system tracks.

Based on the overall suggested timing...a majority of the
precipitation with this system should occur between 3 am and noon
Tuesday. Projected thermal profiles of the atmosphere suggest the
potential for a rain/snow mix south of I-80 with snow north. If this
system tracks further to the south and west then the potential for
only snow will increase.

Snow amounts for this system are still in question. However...very
preliminary amounts suggest the potential for 1-2 inches of
accumulation by sunset Tuesday. These amounts will change over over
the next two days as timing and the eventual track become better

Tuesday night on...

The model consensus has mainly dry conditions Tuesday night through
Thursday night with a general warming trend. However...there is a
weak upper level disturbance that will move through the area on
Wednesday. If forcing/moisture is cannot rule out a
rain/snow mix.

Friday/Friday night a more substantial storm system will move
through the Midwest. The better forcing currently looks to be across
Minnesota and Wisconsin but the individual model solutions vary
greatly on an overall track for the storm. As a result...the model
consensus has slight chance to chance probability of precipitation for the area on Friday
and mainly dry conditions Friday night. Depending upon the track of
the storm...temperatures could be well above normal.

The model consensus has dry conditions across the area on Saturday
as the next Canadian high pressure builds into the Midwest.
Temperatures should average above normal.


Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 549 PM CST Sat Feb 13 2016

VFR conditions expected for most if not all this evening with snow
developing into eastern Iowa towards 06z. The snow will continue to
expand into northeast Iowa and northwest Illinois overnight through 12z
Sunday with all sites deteriorating to lower MVFR and IFR conditions.
These conditions will persist through Sunday am then the snow will
begin tapering off in intensity during the afternoon... although
lower ceilings mainly in MVFR range will linger into Sunday evening.
Winds will shift from the east at around 5-10 kts to the southeast
and increase to 10-20 kts overnight through Sunday.


Dvn watches/warnings/advisories...
Iowa...Winter Weather Advisory from 3 am to 6 PM CST Sunday for Clinton-

Winter Weather Advisory until 6 PM CST Sunday for Des Moines-
Henry Iowa-Iowa-Jefferson-Keokuk-Lee-Louisa-Van Buren-

Winter Weather Advisory from midnight tonight to 6 PM CST Sunday
for Benton-Buchanan-Cedar-Delaware-Johnson-Jones-Linn-

Illinois...Winter Weather Advisory from 3 am to 6 PM CST Sunday for Bureau-
Carroll-Jo Daviess-Putnam-Stephenson-Whiteside.

Winter Weather Advisory until 6 PM CST Sunday for Hancock-

Winter Weather Advisory from midnight tonight to 6 PM CST Sunday
for Henry Illinois-McDonough-Mercer-Rock Island-Warren.

MO...Winter Weather Advisory until 6 PM CST Sunday for Clark-Scotland.



short term...Nichols
long term...08

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