Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 261735

National Weather Service Des Moines IA
1235 PM CDT Wed Oct 26 2016

...Updated Aviation Discussion...

.SHORT TERM.../Today/
Issued at 330 AM CDT Wed Oct 26 2016

Showers and thunderstorms have mostly cleared east of I-35 early
this morning and will continue to move off to the east, departing
the forecast area by around noon. POPs reflect this with a quickly
decreasing trend after the next couple of hours. Meanwhile the
surface low pressure center is entering southwest Iowa at this
time and will make its way across the state today, with winds
behind it turning to northwest and bringing cooler and drier air
into the area. Forecast soundings indicate the near-surface
saturated cloud layer persisting through the day, which is
reasonable given the wet ground and cold air advection. It is
expected that stratocumulus clouds developing through the day will
keep us broken to overcast, at least through early afternoon and
possibly right through to tonight. This will also temper daytime
heating and have held maximum temperatures in check accordingly,
except in the southeast where southerly flow early this morning
should allow for some warm air advection before the low/front
moves through.

.LONG TERM.../Tonight through Tuesday/
Issued at 330 AM CDT Wed Oct 26 2016

Tonight through Friday Night...Confidence High

Fast moving weather pattern to well as high amplitude
wave pattern across the CONUS.  Vigorous shortwaves will continue to
march across the region...with the exodus of the first prior to
this evening and a quick return to warmer air aloft over the west
by Thursday afternoon. A lingering trough aloft will maintain lift
and cloud cover over much of the northeast tonight...and though
H850 temperatures are briefly much cooler in the 1 to 5C range at
00z they warm nicely overnight to about 7-9C in the northeast with
11 to 12C aloft over the central and west. Despite the northwest
flow aloft...warming will commence and at least neutralize cooling
overnight. By Thursday fully expect the warming to commence over
the west while with high pressure anchored over the Great Lakes...
H850 frontogenesis will result across Iowa. This will enhance
cloud cover over the northeast half of the forecast area and
result in quite a contrast in afternoon high temperatures. Over
the northeast upper 50s to near 60 will be common while nearer
Atlantic to Creston... upper 60s to lower 70s may occur. By 12z
Friday a well developed Northern Plains low will track east across
Northern Minnesota. This will result in strengthening warm air
advection through much of the region...H850 temperatures warming
to 14C northeast to 18C southwest by afternoon with strong
southwest winds aloft of 35 to 45kts. Though bufkit soundings
suggest that not all of the warmth will be realized...mixing to
880mb will promote wind gusts of 30 to 35 mph along with highs in
the mid to upper 70s central and south...and lower to mid 70s in
the north. Friday is likely to be the warmest day of the extended.
By Friday evening model consensus is for the boundary to move
south of Iowa with stratus and overrunning light rain possible in
the far north and into Minnesota Saturday.

Saturday through Tuesday...Confidence Medium

Though models are coming into better agreement Saturday...trends
over the past few days have been less than consistent with regard to
the placement of the boundary and how quickly it retreats back
north. With a weak low expected to develop along the boundary
tracking south of Iowa Saturday evening...showers may linger over
the east and south during the overnight hours though confidence not
high enough to include in the forecast at this time.  Cooler
temperatures will return for Sunday with highs in the 50s to mid 60s.
Yet another quickly deepening Northern Plains storm is expected to
move into western Minnesota by 00z Tuesday resulting in strong
southwest flow across the Central Plains. Highs should easily reach
the upper 60s to near 70 north and in the mid 70s across the south
Monday afternoon. Some clouds are anticipated with strong southwest
winds of 30 to 35 mph again.  By early Tuesday a Pacific cool front
will move east followed by a Canadian cold front later on Tuesday.
This will bring colder air to the region later on Tuesday with highs
in the 50s and 60s once again. Little rainfall is anticipated
through the period other than Saturday.


.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.





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