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Area forecast discussion 
National Weather Service Des Moines Iowa
328 PM CST Tuesday Dec 1 2015

Short term /tonight/...
issued at 328 PM CST Tuesday Dec 1 2015

Upper low spinning across the Dakotas/southern Minnesota/western Iowa to continue to
push east across Iowa tonight. System is occluded...but energy aloft
continues to rotate around the center with weak lift in the Omega
fields at 700mb and 850mb. This has been the case for much of the
day and has resulted in light snow across much of the northern
County Warning Area...which is expected to continue through the evening into the
overnight hours. Visibilities have been ranging from around 2 to 5
miles in the snow...and expect those types of conditions to continue
into the evening as well. Overall little accumulation is expected
with around a half inch or less total of new accumulation. With the
low clouds around...warm air advection aloft and winds to stay up a not
expect temperatures to fall off much overnight. Biggest drop is expected
across the south where some peaks of clear skies are possible this
evening...and also where the fresh snowpack is in place across the

Long term /Wednesday through Tuesday/...
issued at 328 PM CST Tuesday Dec 1 2015

Few concerns in the extended this period. Occluding upper low will
continue to drift east in the next 24 hours...maintaining a
lingering presence over Iowa through midday Wednesday. This will
result in clouds and a continued chance of light snow showers or
flurries into the morning tomorrow. The best chances will across
the north in the deformation zone which will weaken toward 18z.
Clouds will be on the decrease northwest with slightly warmer h850
temperatures by late afternoon...reaching 0c near kest by 00z
Thursday. Elsewhere...little moderation of temperature is
anticipated east of i35 where more clouds are expected for the
balance of the morning into early afternoon. Here cyclonic
rotation around the departing upper level low will continue to
promote stratus production. The other limiting factor for highs
Wednesday will be the recent snowfall and ice cover across the
western and northwest counties. Nohrsc snowfall analysis this
morning shows up to a four inch snow cover over the far northwest
and another lobe of 2 to 4 inches in north central Iowa. With
local considerations... highs will range from the lower 30s north
to the upper 30s across the central to southeast where little if
any snow cover is present. By Wednesday night skies will clear out
with temperatures quickly cooling northwest. Guidance latching
onto potential for some upper single digits far northwest where
snowpack is deepest. With the arrival of milder westerly flow
aloft on Thursday...highs will recover quickly during the
afternoon. Both the Euro/GFS advertise warming h850 temperatures into the
4 to 5c range by afternoon. This combined with plenty of sunshine
and some mixing will result in highs moderating to above freezing
northwest to the middle 40s over the central and southeast. By Friday
afternoon...upper level h500 ridge axis overhead with only a slow
drift east expected through Saturday night. Models continue trends
of split flow with deep lows cutting off and undercutting mean
ridge over the Continental U.S.. this results in increasing clouds as upper
level jet energy begins to force some moisture across the ridge
axis and into the central/northern Great Plains. Some
uncertainties come into play by the second half of the weekend as
closed upper level h500 wave begins to move east. Both the
Euro/Gem dig the system into the southern Mississippi River valley
while the GFS is trending slightly north. In either case...little
impacts anticipated other than clouds. Temperatures should remain
mild for early December and above normal. Depending on the track
of the upper level system Monday night into Tuesday... some light
precipitation may accompany the passage of the system across the
region. Beyond the present extended...a continued strengthening of
the eurasia jet across the Pacific should result in wave
instability in the flow along with a more pronounced period of
active weather as we reach the second week of December. A quick
check at thermal considerations suggests that mild temperatures
will also continue.


issued at 1143 am CST Tuesday Dec 1 2015

Area of light snow pushing through much of central Iowa today into
tonight...mainly impacting the northern taf sites with reduced
visibilities at times to mainly MVFR although brief IFR not out of the
question. Possible IFR conditions with ceilings through the
period...with MVFR holding on much of the time. Winds to shift
around to the southwest to northwest through the forecast period
as well.


Dmx watches/warnings/advisories...


Short term...beerends
long term...rev

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