Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 082354

Area Forecast Discussion
National Weather Service Des Moines IA
554 PM CST Fri Dec 8 2017

...Updated for 00z Aviation Discussion...

.SHORT TERM.../Tonight through Saturday/
Issued at 236 PM CST Fri Dec 8 2017

Northerly to northwest flow pattern continues across the region,
with a shortwave trough dropping through the northern regions and
Great Lakes region today into tonight. The associated sfc low
centered over far south central Canada/northern MN currently and
will slide southeastward into MI by early Saturday. Cold frontal
boundary associated with this wave to move through this afternoon
into this evening with CAA expected across the area tonight into
early Saturday. Sfc pres gradient tightens, and will get some
momentum transfer of strong winds aloft to the surface so gusty
northwesterly winds expected tonight into Saturday. Some spots could
briefly touch advisory criteria especially in the N/NE, but overall
widespread advisory criteria conditions not expected at this time.
As the wave moves through MN/WI this evening may see some very light
snow clip the far northeast, with some flurries possible across much
of the north/east. Otherwise deeper moisture and lift situated
closer to the upper wave so better chances for accumulating snow off
across MN/WI. Low clouds to remain across much of the area into
Saturday with some clearing expected through mid to late day.
Temperatures to be cooler for Saturday with highs only in the lower
20s north to around 30 south for Saturday.

.LONG TERM.../Saturday night through Friday/
Issued at 236 PM CST Fri Dec 8 2017

Brief reprieve from the colder conditions for Sunday as a weak
shortwave ridge builds in and have WAA with H85 temps climbing back
into the +5C to +10C range by late Sunday. This should allow temps
to top out around 40 north to around 50 south across central IA.
Another stronger shortwave will dive south/southeastward through the
region Sunday night into Monday. This will send another strong cold
front through the state late Sunday night and allow for another
blustery day Monday. Highs likely earlier in the day with some
steady or falling temperatures for the remainder of the day. GFS
tries to bring some chances for precipitation through the area late
Monday into Monday night, but looks as if moisture may be overdone.
EC/NAM mainly dry with the frontal passage so maybe end up with
flurries at most currently.

Another shortwave trough to drop through the area Wednesday into
Thursday. May again see some small chances for precip across the far
north/east. EC remains drier and warmer than the GFS which keeps the
cold air entrenched across the region. Will have to watch as
temperatures would then trend to near average or below with a
pattern change possible toward the end of next week into next
weekend as the upper level flow pattern looks to become more
westerly to southwesterly.


.AVIATION.../For the 00Z TAFS through 00Z Saturday evening/
Issued at 554 PM| CST Fri Dec 8 2017

Main forecast concerns this TAF period are increasing winds
tonight and low clouds that will persist into the latter half of
the TAF period. The strongest northwest winds are expected
immediately behind a front that will sweep southward across the
state tonight. Wind gusts will be highest across the northern
terminals where gusts will be around 30 knots. Winds will stay
breezy until late afternoon Saturday. Other concern are stratus
clouds that will bring MVFR ceiling restrictions to most terminals
later tonight into tomorrow morning. The highest confidence in
these restrictions and timing is over the northern terminals. May
need to extend MVFR restrictions at KDSM in future TAF issuance.
Otherwise, expect stratus clouds to scatter by late morning with
VFR conditions returning thereafter.




SHORT TERM...Beerends
LONG TERM...Beerends
AVIATION...Ansorge is the U.S. government's official web portal to all federal, state and local government web resources and services.