Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 171140
AFDDMX

AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
540 AM CST Tue Jan 17 2017

...Updated Aviation Discussion...

.SHORT TERM.../Today through Tonight/
Issued at 414 AM CST Tue Jan 17 2017

Lingering dense fog through 12-13z this morning across the
eastern portions of the forecast area are expected. It has already
shown signs of dissipating with the increase of wind speeds but
left the advisory going as portions of Tama, Poweshiek, Black
Hawk, and Jasper reporting 1/4 mile visibility. Other concern was
patchy freezing drizzle over northern Iowa but current weak band
is moving through the MCW area and looks to be quickly east of the
forecast area by 11z or so.

The back edge of the low stratus deck is just entering the far
northwest corner of Iowa and latest trajectory looks to finally
push east of the forecast area late this afternoon, likely after
22-23z, if not later. Extended the cloud cover through the early
evening across the east with the lingering stratus. Otherwise,
temperatures remain on par for today and tonight and made no
significant changes to the ongoing forecast.

.LONG TERM.../Wednesday through Monday/
Issued at 414 AM CST Tue Jan 17 2017

Overall pattern will remain quite active into the longer term with
strong onshore flow onto Pacific Coast with several shortwaves
passing through the central United States. There will be a brief
break at the start of the period with quiet weather after the
current storm departs. However, upper low across the southwest
United States will drift northward by later in the work week. Low
level moisture will surge northward Wednesday night into Thursday
with stratus developing across much of Iowa. In addition, overall
airmass will be relatively warm for mid-January with temperatures
holding above normal from Wednesday into the weekend.

As the various systems lift into the Midwest into the weekend,
forcing will spread across the state from time to time. The
limiting factor for widespread precipitation will be deeper
moisture as most of it will be confined to the near surface status
layer with dry mid levels. However, there will be brief periods
where this is not the case and some light rain will occur from
late Thursday into Saturday. However, the best threat of
precipitation through the next weekend will arrive on Sunday as a
system clips southern Iowa. Deeper moisture is forecast to spread
into the state with some light precipitation possible. At this
time, the bulk of precipitation chances from Thursday into Sunday
should be rain, although there is some threat of snow in the north
from time to time.

&&

.AVIATION.../For the 12Z TAFS through 12Z Wednesday morning/
Issued at 538 AM CST Tue Jan 17 2017

LIFR/IFR ceilings will persist through much of the morning and
slowly lift to MVFR from west to east during the afternoon hours.
Stratus deck is likely to be slow to move out tonight and kept
MVFR ceilings going during much of the evening at OTM, MCW, and
ALO.

&&

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

&&

$$

SHORT TERM...Podrazik
LONG TERM...Cogil
AVIATION...Podrazik



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