Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 251731
AFDDMX

AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
1231 PM CDT Sun Sep 25 2016

.SHORT TERM.../Today/
Issued at 355 AM CDT Sun Sep 25 2016

Precipitation continuing to move across the forecast early this
morning in advance of cold front currently entering western Iowa.
Showers and a few storms will continue across the area during the
morning in advance of the front, but the area will continue to
shrink toward the east as the boundary advances through the state.
Will ride out the flash flood watch for a bit longer as not much
rain would be needed to cause issues, but with limited instability,
rainfall rates will be hard pressed to get very high.  In fact, most
locations that have seen rain the past few hours have not exceeded
0.25" per hour.  Otherwise, much cooler and drier air will
overspread the state today behind the front with west winds picking
up by this afternoon, especially in the north and west.  There will
be some brief clearing the in west this morning, however with cooler
air aloft, anticipate and expansive shield of cumulus to form by
midday into the afternoon with mostly cloudy conditions in most
locations.  Highs will occur early in the east prior to frontal
passage with steady temperatures into the afternoon as cold
advection increases.

As far as rivers are concerned, despite a few areas of heavier
rainfall in the south and central portions of the state, little
additional impact should be seen on those basis, particularly the
Cedar and Iowa from this current rain.

.LONG TERM.../Tonight through Saturday/
Issued at 355 AM CDT Sun Sep 25 2016

Summary...Overall very quiet long term period. Seasonably cool
temperatures to start the week as northerly flow dominates, becoming
seasonable toward end of week. Windy, especially across the north,
Monday as low pulls out of the region. Very limited precipitation
potential end of the week and into next weekend.

Tonight through Thursday...Models continue to be in good agreement
through this period in developing currently passing trough into a
closed low over the Great Lakes region and dropping it into the Ohio
River Valley region by mid week. Coupled with a building western
ridge, flow aloft over Iowa will amplify more meridional, yielding
consistent northerly flow and subsidence. Prior to closed low
development, northern Iowa will see winds approaching 20kts and
gusts to 30kts at times Monday on the backside of the aforementioned
system as it moves into the Great Lakes region. High temperatures
early in the week in the mid to upper 60s before slowly rising into
the low 70s as northerly flow eases. With dry air mass and clear
skies in place, lows will generally be coolest of season in the
40s early in the week before rising into the 50s.

Thursday night through Sunday...Models diverge aggressively during
this period. The GFS, after digging the closed low in the Ohio River
Valley, quickly moves it east while the Euro digs it further south
over Tennessee and even retrogrades as it slowly glides northward
and finally exits eastward. GFS builds in ridging/southwesterly flow
aloft and southerly return flow at the surface with increasing
temperatures. Euro splits flow aloft around the region with primary
influence of northerly flow aloft and at surface while on the
western periphery of the closed low. Hard to put any faith in either
solution at the moment. Fortunately splitting the difference of
little consequence with regards to consequential weather.
Temperatures currently trend more toward GFS in all blends, so if
Euro becomes more viable solution, they are possibly 5 or more
degrees too warm for Sat/Sun.

&&

.AVIATION.../For the 18Z TAFS through 18Z Monday afternoon/
Issued at 1231 PM CDT Sun Sep 25 2016

The IFR to low MVFR clouds are beginning to push east early this
afternoon. Another region of stratus is moving southeast from
South Dakota and Minnesota. This stratus will have some MVFR cigs
with best potential for impact in northern sites including KMCW.
The cigs will clear overnight with SKC expected by Monday morning. Gusty
west winds will prevail through the afternoon before diminishing
overnight. The winds will become gusty once again by mid Monday
morning.

&&

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

$$

SHORT TERM...Cogil
LONG TERM...Curtis
AVIATION...Donavon



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