Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 261141

National Weather Service Des Moines IA
641 AM CDT Wed Oct 26 2016

.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 12Z TAFS through 12Z Thursday morning/
Issued at 641 AM CDT Wed Oct 26 2016

A low pressure center will move across the area this morning
resulting in variable winds. A large stratus field surrounding the
 low will also dominate the aviation forecast through today and
into tonight, with low confidence in evolution of ceiling heights.
 So far IFR ceilings have been prevalent north of the low track
and expect this will continue, but with these clouds rising into
low MVFR by around midday. Further south at DSM/OTM mostly VFR or
MVFR ceilings are anticipated. If the cloud shield holds through
sunset, which appears more likely than not, then ceilings could
lower again tonight with fog developing as a high pressure ridge
moves in and winds go light. This possibility will be fleshed out
in subsequent TAF issuances.





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