Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 220820

National Weather Service Des Moines IA
320 AM CDT Sat Oct 22 2016

.SHORT TERM.../Today/
Issued at 320 AM CDT Sat Oct 22 2016

High pressure has shifted off to the southeast with southwesterly
flow picking up ahead of a developing area of low pressure along the
front range of the Rockies. This will continue the waa regime across
the state today, with h85 temps pushing into the mid teens Celsius
by late this afternoon. This will send temperatures well above the
seasonal averages with highs in the mid 60s north to low 70s south
today. Winds will be lighter out of the south through the day.
Otherwise dry and mostly sunny conditions expected with little
available moisture despite strong WAA.

.LONG TERM.../Tonight through Friday/
Issued at 320 AM CDT Sat Oct 22 2016

Most of the long term forecast is quiet with the exception of a
prolonged period of rain chances between Tuesday and Wednesday of
next week.

From tonight through Monday the forecast is dry with moderate
temperatures. A weak cool front will cross Iowa early Sunday with
high pressure dominating Sunday night through Monday. However,
cold air advection behind the front is not very strong and the
day-to-day temperature drop will only be about 5-10 degrees.

On Monday night, as the high pressure center departs to the east,
we will see a return of southeasterly flow beneath a mid-level
ridge just to our west. An area of theta-e advection will develop
around the Siouxland area with light rain developing over
northwest Iowa late Monday night into Tuesday morning. Meanwhile,
a subtle shortwave impulse moving over the Rockies behind the
mid-level ridge will emerge over the high plains on Tuesday and
deepen rapidly, crossing Iowa by early Wednesday. A surface low
will develop quickly in response, with a zone of frontogenetical
forcing setting up roughly along or near the Iowa/Minnesota
border. The broad forcing for vertical ascent preceding the mid-
level trough will interact with the developing baroclinic zone to
produce showers and a few thunderstorms, mainly across our
northern counties on Tuesday, then spreading east and southeast
with the parent system on Tuesday night into Wednesday. Given the
relative lack of instability and overnight/morning timing of
cyclone passage severe weather probability is low. However, there
may be a heavy rain threat particularly across the north on
Tuesday when the frontogenetic zone may remain nearly stationary.
The hazardous weather outlook will maintain this language

The midweek storm system will move slowly off to the east as a
deep eastern U.S. trough in the latter half of the week, with
quiet and mostly dry weather returning to Iowa during this time.
It appears that another, much weaker mid-level impulse may
traverse the region around next Saturday, just beyond the current
seven day forecast period, and though relatively benign may result
in a return of rain chances around that time.


.AVIATION.../For the 06Z TAFS through 06Z Saturday night/
Issued at 1130 PM CDT Fri Oct 21 2016

Light winds and VFR conditions will prevail through Saturday
evening. Wind will be from the south overnight then become more
southwesterly during the day Saturday.





SHORT TERM...Beerends
AVIATION...Donavon is the U.S. government's official web portal to all federal, state and local government web resources and services.