Scientific Forecaster Discussion
fxus63 kdmx 191045
Area forecast discussion
National Weather Service Des Moines Iowa
545 am CDT Sat Oct 19 2019
..updated for 12z aviation...
Discussion.../today through Friday/
issued at 330 am CDT Sat Oct 19 2019
Nighttime satellite imagery shows cloud cover increasing across Iowa
early this morning as a leading shortwave swings across the northern
plains and into Minnesota. The associated cold front sits across
far northwest Iowa into eastern Nebraska, with associated rain
along the Missouri River in eastern Nebraska and into southwest
Iowa. This will continue to move across Iowa through the morning
before clearing eastern Iowa by early afternoon. Cams have
indicated a slightly slower propagation of the front and so have
trended rain chances to match this. Still expect to see clearing
for the afternoon, with temperatures able to recover into the low
60s for much of the area. With northwest Iowa clearing out
earlier, expect to see afternoon highs there warm a few degrees
more than areas in southwest Iowa with will have lingering cloud
cover to overcome.
With plenty of moisture and clearing skies tonight allowing
temperatures to drop off, expect areas of patchy fog to develop
over portions of southeast Iowa during the early morning hours of
Sunday. This should diminish shortly after sunrise Sunday, with
generally quiet conditions through much of the day. This will not
last as a rather vigorous shortwave crossing The Rockies undergoes
Lee cyclogenesis, deepening as it approaches the area Sunday
evening. With sufficient forcing and some instability, expect to
hear a few rumbles of thunder Sunday night. As this system starts
to lift Monday breezy northwest winds will filter cooler air
across the state. Lingering wrap around rain across northern Iowa
will lift out of the area Monday night, with continued gusty
winds throughout the day on Tuesday. Increased winds throughout
the entire Monday-Tuesday time frame but suspect that this may
need to be increased further with model soundings indicating the
potential for gusts in the 35-40kts range to mix down from aloft.
A quick shortwave will scoot across norther Iowa Wednesday morning
bringing a brief chance for rain before clearing out for the day.
Models diverge from there with the GFS favoring a dry forecast while
the Euro indicates the possibility for additional precipitation
Thursday and Friday. Both models indicate cooler temperatures with
highs by the end of the week in the upper 40s to low 50s and
overnight lows in the low to mid 30s. Should the Euro pan out, we
could see a brief rain/snow mix for the end of the week, however
this would melt on contact and confidence is low given varying model
solutions at this time.
Aviation.../for the 12z tafs through 12z Sunday morning/
issued at 544 am CDT Sat Oct 19 2019
Rain pushing across the state will decrease cigs this morning.
VFR cigs this morning will give way to periods of MVFR cigs
through midday. Expect conditions to clear out this afternoon from
west to east, with winds shifting from northwest to southwest.
Eastern sites kotm/Kalo could see patchy fog develop tonight into