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National Weather Service Des Moines Iowa
1150 am CST Friday Nov 27 2015

issued at 540 am CST Friday Nov 27 2015

Based on latest radar/satellite/surface ob trends over Nebraska
and Kansas...have raised probability of precipitation slightly in southern Iowa for this
morning and early afternoon and added flurries to areas between
Highway 20 and I-80. Radar echos have increased in coverage
upstream in response to a shortwave trough ejecting northeastward
across out of northwest Kansas with a few stations reporting -sn
or -fzra. This trend is handled decently by the rap/hrrr and
leaned towards these solutions for pop coverage through the
morning. Quantitative precipitation forecast amounts should be light with sounding profiles
gradually drying out...but could still squeeze out some measurable
precipitation towards the Missouri border.


Short term /today/...
issued at 316 am CST Friday Nov 27 2015

A quieter day is in store for central Iowa as surface high pressure
currently over the western Dakotas slides east-southeast to the siouxland
region by sunset. The overall upper level pattern will change
little today with a Rex block across the Pacific northwest and a
100 knots jet funneling tropical moisture northward from Hurricane
Sandra in the eastern Pacific. The end result for Iowa will be
continued mostly cloudy to cloudy skies throughout the day as this
midlevel moisture pushes northward...gradually clearing from
northwest to southeast. That being said...there is some
uncertainty as to how long it will take for the low stratus to
clear out of the state (it is late November after all) and the
going sky grids are likely on the optimistic side.

Water vapor imagery depicts a few subtle waves wrapping northeastward
through the mean flow...which may generate pockets of mixed precipitation
showers over the south today. However...with the column drying out
in response to subsidence from the approaching high...quantitative precipitation forecast amounts
will be light.

Long term /tonight through Thursday/...
issued at 316 am CST Friday Nov 27 2015

Only a few challenges for the next 24 to 48 hours...with more
significant system swinging across the region on Monday and Tuesday.
For now...expecting the upper level trough to settle into Missouri
by late tonight into Saturday with surface high pressure building across
the state. Temperatures aloft warm to above 0c at h850 on Saturday which
will allow for some recovery in temperatures during the afternoon.
Sunshine north and some clouds south...with resulting highs above
the freezing mark. This will help some of the ice melt off of trees
and power lines and lessen impacts of any future precipitation
loading on trees et cetera. With the high over northern Iowa and Wisconsin
Saturday night and Sunday...temperatures north will fall into the
teens by Sunday morning. Cloud cover across the south will keep mins
a bit warmer. Vigorous moisture transport continues south of the
state over the weekend with an eventual return to the southwest/
south by Sunday night into Monday as the cut off h500 low now in the
western states moves east with time. This will eventually drift
through Iowa with a variety of winter weather Monday into Tuesday.
Present indications suggest that warmer air will precede the system
and then cold air wraps into it from the west/southwest. Some light
freezing precipitation may occur as the low arrives...becoming a
rasn mixture followed by more snow over the north/northwest Monday
night into Tuesday. Light to moderate accumulations may occur just
to the north of the track of the h500 low...but track and timing
considerations and uncertainties associated with the wave leave too
many details to sort out at this point. Will generalize the trends
with higher pop and suggested ptypes for now. Temperatures through
the period will near normal north and slightly above normal south.
Toward the end of the period on days 6 and 7 the wave departs to the
eastern Seaboard and an h500 ridge with warming temperatures builds east.
Due to the lack of any snow cover to our west and adiabatic warming
across the northern plains...its likely that 40s will return by
Thursday or Friday...possibly warmer.


issued at 1146 am CST Friday Nov 27 2015

MVFR conditions at sites will lift through the period as high
pressure pushes in to northern sites first. Southern
sites...kdsm/kotm may see IFR conditions as system across Missouri
pushes east. Kotm may see -sn or -fzra/-pl near 00z with system.
Conditions will improve beyond 00z at sites...with a return to VFR
conditions expected by 12z. Winds will remain from the north with
gusts diminishing after 00z.


Dmx watches/warnings/advisories...



short term...skow
long term...rev

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