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Area forecast discussion 
National Weather Service Des Moines Iowa
1144 PM CST Wednesday Nov 26 2014

issued at 326 PM CST Wednesday Nov 26 2014

A fast moving pattern with low pressure over northeast MO moving
out of the area as cold high pressure settles on by late Thursday.
The high will move off to the east with south flow becoming
established the next cold front will pass Sunday.


issued at 1135 PM CST Wednesday Nov 26 2014

Little changes were made in this update. The last of the light snow
will exit the southeast County Warning Area shortly which is well trended. The challenge
will be cloud cover and how fast and how far south the clearing
will get overnight. There is a lot of low level moisture in place
but the high is bringing down some very cold and dry air. The far
north and west will clear first and ceilings may lift elsewhere
but the low clouds especially southeast should linger through 12z.
Temperatures across the north remain very cold with wind chills from -15
to -20 by morning. If clouds clear faster further to the
southeast...temperatures and wind chills will have to be revisited as
they may be too warm.

Update issued at 634 PM CST Wednesday Nov 26 2014

Last band of moderate snowfall from Perry through the Des Moines
metropolitan area shifting southeast. The band should be out of the area
by 03z with additional snowfall amounts around a half inch. The
band is weakening as it is moving southeast so moderate snowfall
is becoming more hit or miss. Probability of precipitation were increased in the snow
areas to reflect trends.


Short term /tonight/...
issued at 326 PM CST Wednesday Nov 26 2014

Two main bands of snow that pushed through the area with the warm air advection
snowfall pushing through overnight dropping around 2-4 inches of
snow across much of the County Warning Area...and the warm air advection band then stalling and
pivoting around across central and southeastern Iowa during the day.
Wrap-around moisture allowing snowfall to continue for much of the
day across northern Iowa...has led to some higher than expected snow
totals around 7 inches. Overall as the whole system continues to
drop southeast of the area...the snow will taper off from northwest
to southeast through the early evening hours with the back edge
already situated along and east of a line from Estherville to
Denison. Visibilities have been ranging around one half mile to one
mile in the heavier bands of snow...and expect this to continue or
improve as the snow begins to diminish. Northerly winds have already
increased across the western County Warning Area...and will increase across the
remainder of the County Warning Area as the colder air begins to spill into the
state in earnest. However an area of high pressure to build into the
area quickly will allow for the surface pressure gradient to relax quickly
thus diminishing the gusty wind threat some. Overall in areas that
have already had winds pick up do not see much of an issue with
blowing snow on the web cams. Therefore do not foresee there to be
much as overall intensity of the gusty winds expected to decrease
through the evening as the gradient relaxes.

A weak impulse has also brought some light snow to portions of NE South Dakota
this afternoon will push through southern Minnesota and northern Iowa late this
evening. For the most part any forcing looks to diminish so do not
expect any additional snowfall from this weak impulse later tonight
especially because it has already shown signs of diminishing. As
colder air pushes into the County Warning Area...temperatures should fall but will be
tempered some by the cloud cover. However should still see some
clearing late tonight so lows around zero north and around 10 to 15
above south.

Long term /Thursday through Wednesday/...
issued at 326 PM CST Wednesday Nov 26 2014

After a cold night tonight...temperatures will be slow to rise tomorrow
with fresh snow in many locations and winds light...limiting
mixing. As the high moves off tomorrow night...strong warm air advection will
begin. Expect to see temperatures steady or rising through the night and
went with a non-diurnal temperature trace. Warming will continue through
Friday with temperatures getting back above normal.

The warmest air will pass over the state Friday. GFS and ec both
in good agreement with the +16 passing over southern and western
Iowa during the day Sat. Bumped up temperatures for that period on the
Assumption that the snow will have melted by then. The other
possible issue is the potential for stratus and fog for form and
not break. I would have bumped up temperatures another 5 to 8 degrees of
not for these two considerations.

The rest of the forecast period looks quite. A strong cold front
moves through last Sunday night or Monday...but with little
fanfare. Temperatures will return to more normal levels with a
generally dry period.


issued at 1135 PM CST Wednesday Nov 26 2014

The last of the snow will exit kotm by 07z. High pressure will
build into the taf locations bringing in gusty northwest winds through
12z. There will be clearing as well but the southeast will hold
onto the IFR stratus the longest. Kfod and kmcw should become MVFR
or VFR by 09z and all taf locations will be VFR by 14z. Surface winds
will diminish as the high settles in and by late in the taf period
they will eventually switch to the southeast.


Dmx watches/warnings/advisories...


synopsis...MS Nov 14
short term...beerends
long term...MS

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