Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 241721

National Weather Service Des Moines IA
1221 PM CDT Mon Oct 24 2016

.SHORT TERM.../Today/
Issued at 316 AM CDT Mon Oct 24 2016

Surface cold front has pushed south of the area, however the front
aloft has stalled across the CWA. Therefore still have some warmer
temps aloft across the south and west, with cooler temps to the
north and east. Therefore have nudged temps across the south and
west a degree or two higher with mostly sunny skies and dry
conditions expected as high pressure builds into the state.
Northerly to easterly flow to dampen warming some, but overall
another beautiful late October day expected. Slightly cooler temps
across the north into the mid/upper 50s, but still above average
for this time of year.

.LONG TERM.../Tonight through Sunday/
Issued at 316 AM CDT Mon Oct 24 2016

A persistent gyre will spin off the northwest U.S. Pacific coast
for the next several days. An energetic shortwave impulse ejected
out of this system will cross the Rockies tonight and mature as it
crosses the Midwest between Tuesday and Wednesday. In our area and
at the surface, a high pressure ridge will slide away to the east
tonight, replaced by southeasterly flow as a low pressure area
develops in Kansas/Nebraska ahead of the approaching mid-level
trough. This low pressure center will subsequently move across
Iowa in conjunction with the mid-level system, bringing
precipitation to most or all of Iowa especially on Tuesday night
into Wednesday morning. Instability is limited particularly with
the low crossing our area during the night, however, enough is
present in the column to generate some thunderstorms. Also,
precipitable water values are unseasonably high at nearly an inch
and a half and given the widespread forcing accompanying the
storm system, locally heavy rainfall remains a threat. Prognostic
guidance has backed off just a bit on QPF tonight, but widespread
amounts around or a little under an inch can still be expected,
with higher amounts mainly across the northern half of the service
area. Given the antecedent conditions significant impacts are not
anticipated at this time, but the threat will be closely monitored
over the next couple of days.

Once the rain moves off to the east with the parent system on
Wednesday, several days of dry weather are in store. A large high
pressure ridge will develop over the western U.S., downstream of
the gyre off the northwest coast, placing Iowa beneath benign
northwesterly flow from Wednesday through Thursday. The northwest
gyre will eject another vigorous shortwave eastward over the top
of the ridge late in the week, maturing over the Upper Midwest
around Friday or so. However, our area looks to be on the
southwestern periphery of this system and moisture is much more
limited, so precipitation is unlikely and the more sensible effect
will be the passage of a cool front late Friday or Friday night.
Behind this front temperatures will be closer to seasonal normals
next weekend, with daily highs in the mid-50s to lower 60s and
overnight lows in the mid-30s to lower 40s. After that steering
flow will become more zonal overhead, resulting in generally quiet
weather with slowly moderating temperatures early next week.


.AVIATION.../For the 18Z TAFS through 18Z Tuesday afternoon/
Issued at 1220 PM CDT Mon Oct 24 2016

There is a high confidence in VFR conditions through at least the
evening hours with nothing more than patchy mid or high clouds.
Low level moisture will develop and increase through the Missouri
Valley toward daybreak however and may lead to MVFR stratus
reaching SW Iowa and potentially just getting to KDSM by late
Tuesday morning.





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