000
FXUS63 KDMX 182250
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
550 PM CDT Thu Apr 18 2024

 ...Updated for the 00z Aviation Discussion...

.KEY MESSAGES...

- Showers and storms ending southeast this evening with skies
  clearing from northwest to southeast statewide.

- Freezing temperatures possible tonight resulting in Frost
  Advisories and Freeze Warnings for the state.

- Gusty winds on Friday, mainly across northern Iowa. Freezing
  temperatures likely again Friday night into Saturday, then
  again Saturday night into Sunday.

&&

.DISCUSSION...
Issued at 247 PM CDT Thu Apr 18 2024

>> Showers & Storms Departing This Afternoon

After a moist morning across the forecast area, rain has departed
all but southeastern Iowa where scattered showers and a few
thunderstorms remain. Fortunately, the better instability has stayed
south of the state and therefore severe weather chances for this
afternoon have diminished. These showers and storms will exit Iowa
through the late afternoon as the cool front continues through the
state. Behind this boundary, cooler and drier air has begun to
funnel in and erode cloud cover in northwest Iowa. Cloud cover will
continue to diminish from northwest to southeast through the
afternoon and evening hours, leaving mostly clear skies through the
overnight.


>> Frost and Freeze Conditions Tonight

With colder air advecting into the area, clearing skies, and
diminishing winds, expecting some efficient cooling through the
night with temperatures dropping into the low to mid 30s by early
Friday morning. With recently warmer temperatures and rainfall, much
of the vegetation across the area has started to green up and
growing seasons will be beginning soon. Therefore, in collaboration
with neighboring offices, have issued a freeze warning for much of
northern, central and western Iowa where temperatures will be near
to below freezing. Similarly, a frost advisory has been issued for
counties further south and east in the state where temperatures will
be slightly warmer (mid 30s) but dewpoints still fall into the upper
20s to low 30s with light winds, posing the risk for frost. That
being said, with strong radiational cooling expected, lows very well
could fall below what is currently forecast, so all areas should be
prepared for freezing temperatures and/or frost on Friday morning.


>> Breezy Tomorrow

Friday looks to be breezy as an upper level ridge passes to the
north of the state, bringing tightened pressure gradients and a
decent jet aloft that will be maximized over northern Iowa. With
clear skies and the passage of another cold front, winds should have
no problem mixing down to the surface, producing gusty winds along
this boundary and beneath the jet across the north. The strongest
winds will likely be sustained at 20 to 25 mph, with gusts exceeding
35 mph at times in the afternoon. That being said, not anticipating
much fire weather concern with the two recent rainfall events
keeping fuels moist. Tomorrow night, temperatures will be even
cooler with widespread lows below freezing, making freeze headlines
likely again tomorrow night into Saturday morning.


>> Seasonal Temperatures Next Week, Rain Chances Return

Outside of overnight freezing temperatures this weekend and gusty
winds tomorrow, the forecast looks relatively quiet through the
weekend. Temperatures will begin to warm back to normal through the
beginning of next week, with a few chances for rain early and late
week. The first of these looks to be on Monday, with the chance for
both rain and a few thunderstorms. This system is still a ways out,
but as of right now it looks like modeled precipitation is favoring
northern Iowa. There is little concern for severe weather at this
time as most of the instability stays outside of the state. Beyond
that, we will have to wait until closer to the event when details
are clearer.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 550 PM CDT Thu Apr 18 2024

MVFR conditions at the start of the period in our far southeast
forecast area impacting OTM will give way to VFR conditions
early this evening. Thereafter, there is high confidence in VFR
conditions prevailing through the period. Breezy daytime winds
from the northwest will relax tonight becoming from the west.
Winds will return to from the northwest on Saturday turning
gusty once again later in the morning through the afternoon. The
strongest winds will be over northern Iowa where gusts to
around or over 30 knots are forecast.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 1 AM to 8 AM CDT Friday for IAZ004>007-
015>017-023>028-033>038-044>046-057-070.
Frost Advisory from 1 AM to 8 AM CDT Friday for IAZ039-047>050-
058>062-071>075-081>084-092>095.

&&

$$

DISCUSSION...Dodson
AVIATION...Ansorge