Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 080518

Area Forecast Discussion
National Weather Service Des Moines IA
1118 PM CST Sun Mar 7 2021

...Updated Aviation Discussion...

.DISCUSSION.../Tonight through Sunday/
Issued at 319 PM CST Sun Mar 7 2021

Forecast Highlights:
-- Extreme fire weather conditions over parts of southern Iowa - Red
Flag Warning continues until 6pm.
-- Ice jam potential, though this risk continues to lower (see
HYDROLOGY section).
-- Above normal temperatures through midweek with near record or
record highs/high low temperatures possible.
-- Cold front brings chances for thunderstorms midweek followed by
cooler, but still above normal temperatures.
-- Wintry precipitation next weekend?

Continuing the forecast highlights and the hydrology section from
the last discussion here as the highlights summarize the abundance
of weather phenomena today into this upcoming week and little to no
changes to mention since this morning with regards to ice jam

Extreme fire weather conditions this afternoon over parts of
southern Iowa with sustained winds between 20-25 mph and gusts of up
to 40 mph paired with RH values in the mid 20s and cured fuels. This
has created prime conditions for rapid fire spread and as such, the
Red Flag Warning will continue through when winds start to decrease
after 00Z.

Warm air advection has once again helped temperatures today climb
into the mid to upper 60s as of 2pm with some areas of southwest
Iowa expected to be just shy of 70 this afternoon. Some snow cover
still remains in east central to northeast Iowa and is keeping
temperatures lower than other areas of the state, though the near-60
degree temperatures are certainly melting some of the remaining
snowpack! Winds tonight will taper off as the pressure gradient
lessens with the cold front stalling just north of Iowa and although
somewhat flatter than today, mid-level ridging will remain in place
to start the new week keeping tonight clear and a little more mild
with low temperatures in the mid 30s north to mid 40s south.

With the ridge in place little change to temperatures
Monday and Tuesday from today, though a few more 70s could be seen
on Tuesday with additional warm air advection and stronger
southerly winds aided by a warmer start from Tuesday morning`s low
temperatures. The only thing that could keep us from potentially
reaching record highs on Tuesday would be a low cloud layer with
some developing saturation around 850.

The pattern will finally change on Tuesday as the ridge in place
finally moves off to the east. A low pressure will track
northeastward towards the state bringing some showers and possible
thunderstorms on Tuesday night into Wednesday with some weak
instability in place. An associated cold front will bring some
cooler temperatures to end the week, though highs will still be
in/near the 50s.

Another system may impact the area next weekend but many
inconsistencies still remain in the models. Some models suggest a
completely dry forecast while others have a mix of rain and wintry
precipitation for the state. Have remained with NBM guidance for
now and will continue to assess the impacts, if any, to the state
as model certainty increases.


.AVIATION.../For the 06Z TAFS through 06Z Monday night/
Issued at 1116 PM CST Sun Mar 7 2021

LLWS continues overnight into early Monday morning. Expect up to
40 to 45kts difference by 2000 feet AGL. Otherwise VFR conditions
prevail through the current TAF period.


Issued at 411 AM CST Sun Mar 7 2021

A late week satellite pass for areas east of I-35 shows that
there is little ice left in the Raccoon River with the exception
of the North Raccoon River upstream of Adel and some ice with
between Perry and Jefferson. That said, there is plenty of open
water on the North Raccoon. While there remains quite a bit of
ice on the Des Moines River upstream of Saylorville Lake, there
are more open water areas than there were last Tuesday. Overall,
the threat for ice jams continues to lower and is seemingly
relegated to river bends or where the channel narrows and even
that may not cause a river area to reach flood stage.




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