Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 271203
AFDDMX

AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
703 AM CDT Tue Sep 27 2016

...Aviation Update...

.SHORT TERM.../Today/
Issued at 250 AM CDT Tue Sep 27 2016

For the most part, conditions have not changed much and in many
ways will be quite similar today as they were yesterday. The upper
low responsible for the northwesterly flow will continue to dig
its way southward, centering itself roughly near the IL/IN border
this afternoon. Winds will remain on the breezy to gusty side,
though a bit lighter for some and more northerly. With thermal and
mechanical driven mixing to at least 850mb expected, sustained
winds around 15 to 20 mph and gusts to 30 mph likely across the
northeast half to two-thirds of the state. Dew points likely to
dip back into the low to mid 30s during the afternoon with the
aforementioned mixing and dry air mass remaining over the area.
Temperatures should remain in upper 60s to low 70s for much of the
area with cloud cover not moving in until the evening hours.

.LONG TERM.../Tonight through Monday/
Issued at 250 AM CDT Tue Sep 27 2016

Main precip chances will come early and late in the forecast
period, with the best chances late. Otherwise, main forecast
challenges include temps and cloud cover around the Wednesday time
frame.

Deep upper low will travel southward through Wednesday, and will
be centered over the Chicago area by Wednesday morning. Decent
synoptic forcing will be evident this evening mainly across the
northeastern half of the CWA, coincident with a cold front diving
southward. Best moisture will remain to just the east of the CWA.
Even so, have kept slight chance POPs for RW across the far
northeast this evening.

Models have been having some difficulty handling cloud cover--and
as a result, max temps--on Wednesday. Have increased cloud cover
on Wednesday especially across the northeastern half of the CWA,
and have lowered the blend of temps for that day as well.
Conditions will be breezy on Wednesday with a relatively tight
pressure gradient. The gradient will relax slightly toward
evening.

After Wednesday, the upper-level low will push slightly
southeastward and will amble around the middle Ohio River valley
until Saturday. At that time the low will travel northward again
toward the south central Great Lakes region, and will continue
traveling northeast in response to a digging longwave trof across
the far western U.S. by Sunday. Shortwave trof ejects eastward
rapidly from the longwave trof, and will bring changes to our
sensible wx by Monday evening. Warm air advection ahead of the
approaching storm system will bring chances for SHRA/TSRA Monday
night primarily to the far western CWA.

&&

.AVIATION.../For the 12Z TAFS through 12Z Wednesday morning/
Issued at 700 AM CDT Tue Sep 27 2016

VFR expected through the TAF period, though winds will be breezy
and gusty once again today. Northerly winds around 15 kts with
gusts to 25 kts or more, with strongest around KMCW/KALO.
Otherwise, cloud cover moving in to KMCW/KALO in the
afternoon/evening hours likely dropping into low VFR territory
overnight.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Curtis
LONG TERM...Zogg
AVIATION...Curtis



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