Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 241004

Area Forecast Discussion
National Weather Service Des Moines IA
404 AM CST Wed Jan 24 2018

.SHORT TERM.../Today/
Issued at 400 AM CST Wed Jan 24 2018

A surface high pressure system was centered over the Oklahoma and
Texas panhandles this morning and ridged north through far western
Iowa and northward. A large area of stratus remained trapped under
the inversion aloft, just east of the ridge and encompassed much of
central Iowa and western Minnesota/eastern Dakotas. The stratus
steering flow early this morning remained out of the northwest
therefore the clouds will be persistent this morning before the
steering winds become more westerly later today. A region of cirrus
will arrive this afternoon thus even with the stratus eroding, any
sunshine will still be filtered. Areas of fog have developed along
the western fringe of the status, some of which was dense near Sioux
City. The fog will clip the far western sections of the forecast
area mainly along and west of a Lamoni to Sac City line.

Flurries will be exiting the area soon then no other precipitation
today. High temperatures today will be dependent on sky cover and
snow cover. Highs are expected to be in the upper 20s north to upper
30s to around 40 south.

.LONG TERM.../Tonight through Tuesday/
Issued at 400 AM CST Wed Jan 24 2018

The long term forecast period remains quiet and generally mild and
dry. Tonight a surface ridge will move away well to our southeast
as a large mid/upper level ridge approaches from the west and warm
air advection aloft edges into our forecast area. This combination
will result in the development of a weak effective warm front
somewhere across our area. With light winds and a shallow
saturated layer at/above the surface there is potential for fog
development, especially across about the northern half of Iowa,
however confidence is low and if the clouds today do not clear out
by tonight then ceilings already being in place would greatly
mitigate any fog threat. Therefore, have left it out of the
forecast for now.

From Thursday into Friday low-level flow will steadily strengthen
and turn through south to southwest, even as the large thermal
ridge passes overhead. This will support pronounced warming and
have maintained previous temperature forecasts and even raised
them a bit more across our southeast half on Friday. If everything
lines up it is not far-fetched to think a station or two could hit
60 degrees on Friday afternoon. A cool front will push across the
region around Friday evening, moderating temperatures somewhat,
but readings this weekend should still be a little above normal.
The frontal passage appears dry with most associated moisture
advection being shunted off to our southeast, and no POPs are
included at this time.

After the relatively cooler weather from Saturday into Monday,
another surge of warm air advection appears on tap next Tuesday,
with temperatures even at this range already forecast in the mid
40s to lower 50s. However, this warmup will be cut short by the
passage of another frontal system somewhere around next Wednesday.
While this system has a better chance to produce some
precipitation across our area, this far out any details of timing,
temperature profiles, etc. are uncertain at best. Given the warm
air in place ahead of the system and its apparently progressive
nature, it is likely we would see fairly limited precipitation
amounts and probably mainly in the form of rain. Of course a lot
could change in the next week.


.AVIATION.../For the 06Z TAFS through 06Z Wednesday night/
Issued at 1140 PM CST Tue Jan 23 2018

Low stratus in place across much of the area with some clearing
in the northeast initially. Low clouds should move back in. Fog
will be possible in the far west, but more confined to areas where
the stratus deck has moved out of the area further west of the
forecast area. CIGS to be mainly IFR/MVFR and will begin to erode
through late morning/mid-day Wednesday. Winds to still shift
around to the west to south through the period. Chance for fog
again Wednesday night just beyond the current forecast period.





SHORT TERM...Donavon
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