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FXUS63 KDMX 090432

Area Forecast Discussion
National Weather Service Des Moines IA
1132 PM CDT Thu Jun 8 2023

Issued at 921 PM CDT Thu Jun 8 2023

Forecast remains on track this evening. Satellite imagery was
depicting an area of upper level smoke across eastern portions of
the CWA but expecting no surface impacts. Otherwise, expecting a 
calm evening with low temperatures in the 50s and light 
east/southeasterly winds. Latest CAMs are depicting scattered 
showers and thunderstorms entering the western CWA in the 18z-19z 
time frame and have adjusted PoPs this evening to account for 
this. Will continue to monitor progression this evening and into 
the overnight.


...Updated for the 06z Aviation Discussion...

.DISCUSSION.../Tonight through Thursday/
Issued at 201 PM CDT Thu Jun 8 2023

Key Messages:

-Rain has ended in the southwest, and the next 24 hours will be 
 pleasant and dry.

-Rainfall remains forecast in the Friday through Sunday period,
 with uncertainty on placement and intensity of rain amounts.

Remarkably dry air is found over the Great Lakes region, and this
is spreading west on the light east to southeast winds surrounding
the high pressure over Wisconsin. Dewpoints in the upper 30s to
lower 40s already have spread into areas east of I-35, with the
last of relatively moist air exiting our southwestern counties
this afternoon. 

The next 24 hours, this pleasant, dry air mass will dominate our
weather, with lows falling the mid 50s west to low 50s east under
clearing skies tonight. Friday and Friday night, the dry air will
allow for a quick warm up into the lower 80s for highs, followed
by lows in the upper 50s to around 60 Friday night. Friday night,
increasing moisture will begin to spread into Iowa, and chances
for high based showers and some thunderstorms will be on the
increase from west to east during the evening and overnight. 

Over all, the signal for showers and storms Friday night through
Saturday is rather broad, and not consistently forecast by any
model set. In general, the best forcing appears to be in the west
1/2 late Friday night through Saturday morning, then that axis
spreads east Saturday afternoon through Saturday night as a 
strong upper wave digs into the Cornbelt. There is rather good 
ensemble model support for a more widespread rainfall event 
centered on Saturday, with a low potential for heavy rainfall. 
Locations for that heavy rain are not confidently identified yet, 
but amounts could be over 1 inch in an axis within Iowa, as a 
closed mid level circulation spread eastward Saturday afternoon 
through Saturday night. Deterministic model runs show this as far 
north as northern Iowa, and as far south as Missouri, but the mean
is generally showing the highest probability for rainfall over 
central and southern Iowa. 

Given the rainfall and cloud cover expectation Saturday into 
Sunday, high temperatures are expected to be seasonally cool - in
the mid to upper 70s Saturday, and lower to mid 70s Sunday. 

The remainder of the forecast continues below normal highs in the
70s through Monday, followed by a warming trend back to the lower
to mid 80s for Tuesday through Thursday. NBM pops show slight to
low end chances in the mid to late week, but this is trending
down in this ensemble run, and may be a dry period of warming in
the next run of the NBM, as there is little focus for rainfall,
and low level air is expected to be seasonally dry. 


.AVIATION.../For the 06Z TAFS through 06Z Friday night/
Issued at 1132 PM CDT Thu Jun 8 2023

Expect VFR conditions to continue throughout this TAF period.
Showers and thunderstorms may form in areas northwest of a KCIN 
to KMCW line towards the 18z-19z timeframe as a frontal boundary
moves through, but confidence is low on impacts to KFOD and KMCW 
so have left out VCSH/VCTS mentions for now. Will continue to 
monitor trends and update in further issuances. Winds will favor 
an easterly/southeasterly direction early in the period and then 
switch to a more southerly direction around the 0z timeframe, 
staying at 10 kts or less.