Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 161717
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1217 PM CDT Sun Apr 16 2017

.SHORT TERM.../Today through Tonight/
Issued at 336 AM CDT Sun Apr 16 2017

The cold front has passed through central Iowa and high pressure
will now build into the state making for a much quieter day today.
We will remain in Northwest flow through today so temps will be
cooler than we have seen but still normal to slightly above normal
for mid-April.  Soundings show some very dry air moving in as well
so we should have good mixing in the late morning and afternoon.
Aloft wind speeds are 15 to 25 kts so there may be some wind gusts
to deal with this afternoon.

Tonight the surface high slips East and winds become light and
variable.  A low drops Southeast across Canada into the Great Lakes
by Monday morning and pushes a shortwave across MN that does brush
far Northern/Northeast Iowa.  However soundings remain dry so other
than some mid level clouds the shortwave will pass with little
concern.

Within bank rises of rivers from last nights rainfall will need to
be monitored but at this point widespread flooding is not
anticipated.

.LONG TERM.../Monday through Saturday/
Issued at 336 AM CDT Sun Apr 16 2017

A very active pattern will continue through the forecast period.
Monday still looking like a best day of the week with a ridge of
high pressure over Iowa and high temperatures in the upper 60s to
mid 70s. A strong PV anomaly will cross the Rockies Monday night
then move east across the Dakotas and Minnesota on Tuesday. A
surface low pressure will develop in response to the upper level
system and will drag a cold front through Iowa Tuesday. A few
showers and thunderstorms may develop across central Iowa along
the boundary though solutions are trending toward a less areal
coverage for precipitation. Proximity sounding profiles suggesting
that a weak cap aloft combined with much of the dynamic forcing
remain north of Iowa may limit the overall coverage.

Surface high pressure ridge will arrive Tuesday night though
another area of low pressure will already be developing over
eastern Colorado and western Kansas as the next strong upper level
system crosses the Rockies. This will place a warm front just
south of the state Tuesday night then lift into southeast Iowa on
Wednesday. This will result in good instability into portions of
southern Iowa by Wednesday afternoon. Should this scenario unfold,
strong to severe storms would be possible over the southern
portion of the state by Wednesday afternoon and evening.

Cooler conditions will follow on Thursday. Also Thursday, the next
strong upper level system will already be moving into the
southwest CONUS. This upper level system is expected to evolve in
a closed upper low by Friday then pass slowly south of the state
into next weekend. As of now, Iowa likely will be on the cool side
of this system and more in the overrunning/deformation region with
little convective instability. Saturday in particular could be
cool and wet. Current forecast high temperatures on Saturday are
in the mid to upper 50s. The raw model output would suggest closer
to mid to upper 40s over central and southern Iowa under the thick
clouds and rain. Drier conditions are expected across northern
Iowa with high pressure situated just to the north. Will be a
balancing act between the drier air to the north and the Gulf
moisture streaming towards the state.

&&

.AVIATION.../For the 18Z TAFS through 18Z Monday afternoon/
Issued at 1218 PM CDT Sun Apr 16 2017

While there may be times of high level clouds throughout the TAF
period, conditions will remain VFR at all terminals through the
TAF period. Gusty winds from the northwest mainly over the
northern terminals this afternoon will become light and variable
this evening as high pressure moves across the state.

&&

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

$$

SHORT TERM...FAB
LONG TERM...Donavon
AVIATION...Ansorge



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