Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 251136
AFDDMX

AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
636 AM 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 12Z TAFS through 12Z Monday morning/
Issued at 636 AM CDT Sun Sep 25 2016

Main concerns will be in the first 6 hours of the forecast with
areas of low ceilings, restricted visibilities and scattered
showers across central Iowa. This activity will come to an end as
a cold front slides across the area this morning. Will see
ceilings increase to VFR by midday at all locations with
increasing west to northwest surface winds as cold advection
increases. By tonight, widespread VFR conditions are expected with
unrestricted visibilities and ceilings with light west to
northwest winds.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 10 AM CDT this morning for IAZ006-007-
016-017-025>028.

&&

$$

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


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