Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 262033

National Weather Service Des Moines IA
333 PM CDT Wed Oct 26 2016

.SHORT TERM.../This evening through Thursday/
Issued at 333 PM CDT Wed Oct 26 2016

The main forecast concern is the low stratus deck hanging
around through tomorrow morning.  Inversion continues to strengthen
this evening into the overnight hours trapping the low stratus deck.
Little evidence suggests the cloud deck to erode this evening and
have increased cloud cover through 12z Thursday for the majority of
the forecast area. The inversion is probably the weakest in the
southwest, but then the this area likely see fog develop with the
light winds and low RH values. Have patchy fog past 08z Thursday
over the western portions of CWA in the event there are some breaks
in the cloud deck.  The HRRR as well as a the majority of the other
hires models continue the stratus through at least 09-12z Thursday
before they suggest some holes develop in the stratus. This makes
temperatures another concern tonight. If any clearing occurs,
especially over the west in Nish Valley and across the north,
minimum temperatures likely will be off by several degrees. However,
even if breaks do occur, it`s likely to fill back in fairly quickly
and thus the potential exist for fluctuating temperatures throughout
the night.

.LONG TERM.../Thursday night through Wednesday/
Issued at 333 PM CDT Wed Oct 26 2016

High pressure ridge will be stretched over central Iowa mid
Thursday morning then will move slowly east during the day. Warm
advection will be ongoing to the west of the high pressure however
a steep inversion setting up between 900-850 mb and will limit
temperature recovery. Also the steep inversion combined with the
light flow directly under the high pressure may slow the
erosion/departure of stratus over the east to northeast portion of
the area. Warm advection will increase Thursday night into Friday
as the pressure gradient increases with low pressure moving into
the Northern Plains.

The thermal ridge will pass over Iowa on Friday. A big inversion
remains aloft to start the day though should be able to mix
through a good portion of it for highs to reach the mid to upper
70s at most locations. Model profiles look too bullish on
potential high level cloudiness during the afternoon therefore
should have an abundance of sun throughout the day. A boundary
will sag into Iowa Friday night then move very slowly south during
the day Saturday as it becomes nearly parallel to the upper zonal
flow. Moisture will be quite limited along the boundary with no
precipitation expected central and south Saturday. Low chances for
precipitation north though profiles will remain dry below 700 mb
with anything that occurs remaining light. Another strong short
wave trough moving the the flow will arrive late Monday into
Monday night with the ECMWF remaining around 9 hrs slower than the
deterministic GFS and ensembles. The primary impact of the timing
will be high temperatures on Monday with the thermal ridge
becoming reestablished and potential remaining over Iowa much of
the day. Precipitation chances should be mainly relegated north of
 Iowa and generally along and north of sfc low pressure that will
pass north of the state as well. High pressure will follow for
Tuesday. Precipitation chances will increase Tuesday night into
Wednesday as warm advection develops in the wake of the departing


.AVIATION.../For the 18Z TAFS through 18Z Thursday afternoon/
Issued at 1228 PM CDT Wed Oct 26 2016

LIFR/IFR ceilings look to continue throughout the afternoon into
tonight. Confidence is high that this low stratus deck will
linger into Thursday morning, but low confidence with the flight
category. Likely to remain b/t 500-1000 feet at MCW/FOD/ALO for
much of the TAF period with DSM/OTM on the southern fringe of this
IFR stratus. Kept MVFR stratus through tomorrow morning as much of
the low level RH remains trapped under the inversion tonight.
Visibility has improved with the drizzle dissipating and only
looks to impact OTM through the early afternoon.




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