Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 011125

Area Forecast Discussion
National Weather Service Des Moines IA
525 AM CST Mon Mar 1 2021

.SHORT TERM.../Today through Tuesday/
Issued at 235 AM CST Mon Mar 1 2021

Confidence: High

A couple of forecast challenges into tomorrow, but overall a fairly
quiet week ahead as the upper level pattern swings from a northwest
to west southwest flow in the next few days.  Today the main player
is another cold front and weak area of low pressure over eastern
South Dakota which will drops southeast over Iowa today and weaken
by late afternoon. Currently there is a an area of light snow and a
mix along the boundary where both warm air advection and frontal
forcing are being maximized from central and southeast Minnesota
this morning. This area is expected to pass into Wisconsin and
northeast Iowa, just brushing our far north northeast this morning
with either flurries or a brief hour or so of non impactful light
snow. Clouds and colder air associated with the boundary will drop
over the region today. As H850 temperatures fall off this afternoon,
the northeast will see about -8 to -10C between 18 and 00z while the
south drops to -6 to -7C by 00z. This will keep highs in the lower
to mid 20s north and highs from south central to southern Iowa will
reach the mid 30s to lower 40s. By late afternoon some breaks in the
clouds and sunshine over the north will at least make the day feel a
bit better.  Tonight with high pressure and the coldest air we will
see in a while overhead through evening, lows are likely to drop off
into the lower teens east/northeast while the south and west reach
the lower to mid 20s. Good news returns already tomorrow with a
decent push of adiabatically warmed air into the region by 00z Wed.
Brisk west winds aloft and warming H850 temperatures to 3C east to
5+ C west should help bring highs back in the lower 40s northeast
where snowpack continues to the mid to upper 50s in the south.  The
west may reach the lower to middle 50s if mixing can break through
the inversion there by afternoon. Though it will be of little
influence, another weak trough may drop south by Tuesday night.

.LONG TERM.../Tuesday Night through Sunday/
Issued at 235 AM CST Mon Mar 1 2021

Confidence: High

A rather quiet and dry period with warming temperatures is expected.
Skies will remain generally clear Tuesday night with little change
in the airmass over Iowa. Lows Tuesday night will fall back into the
mid 20s north to the lower 30s south with light winds. The remainder
of the week continues quiet with mild temperatures again Wednesday
and Thursday.  Highs will again reach the 40s over the northeast
half and the mid to upper 50s in the southwest half. By Friday into
Saturday, there is still a signal for a slight retrogressing of the
H500 low over eastern Canada which will allow for a shortwave to
drop south into the western Great Lakes and lower temperatures as
far west as Iowa. This may also introduce more clouds as
frontogenesis is induced by the retrogressing cold air east and the
warmer air west. Overall this will not have a major impact on our
temperatures, with only a few degree drop into Friday and Saturday
prior to a return push eastward of the milder conditions developing
west. As another shortwave tracks into the Northern and Central
Plains, it will pull another burst of warm H850 air into the region
Sunday into Monday. For one or both days, we will have a chance of
reaching afternoon highs in the upper 50s to lower 60s over the
southwest to near south central while the northeast will be nearing
50 degrees Sunday and possibly the lower to mid 50s early next week.
Despite a more westerly to southwesterly flow aloft, there remains
little signal of any significant precipitation this upcoming week
and into next weekend.


.AVIATION.../For the 12Z TAFS through 12Z Tuesday morning/
Issued at 525 AM CST Mon Mar 1 2021

Changes made for approaching cold front and flurries along with
MVFR cigs. Hires models and trends suggest that band of lower cigs
will pass south more or less intact through 19z prior to some
lifting of ceiling as boundary layer deepens. Have added MVFR to
KFOD,KALO, and KMCW along with VCSH for flurry chances at KMCW and
KALO. Otherwise, winds shift to north northeast aft fropa. Aft
19-20z VFR conditions return with light winds aft 00z.




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