472
FXUS63 KDMX 071935
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
235 PM CDT Fri Jun 7 2024

.KEY MESSAGES...

- Showers and a few thunderstorms tonight into early Saturday.
  Low risk of severe weather in the southwest.

- Generally dry, comfortable, and quiet from later Saturday
  through Monday.

- Becoming warmer, and more active at times, in the latter half
  of next week.

&&

.DISCUSSION...
Issued at 235 PM CDT Fri Jun 7 2024

Iowa currently resides beneath relatively brisk west
northwesterly steering flow aloft, which will continue through
the weekend. A shortwave impulse traveling through that flow is
currently crossing South Dakota and Nebraska and kicking off
severe storms there. Ahead of this system, currently in Iowa a
surface high pressure area continues to dominate and despite
modest lift producing radar returns, little to none of this is
reaching the ground due to substantial low-level dry
air/subsidence with dewpoint depressions of around 35 degrees
being observed in our forecast area.

This evening and tonight as the aforementioned shortwave
approaches the atmosphere will gradually attempt to saturate and
lift will increase, however the storms currently over north
central Nebraska will progress more southeastward toward greater
instability and the developing low-level jet. While those storms
will likely congeal into an MCS as they encounter an environment
increasingly favorable for severe weather, CAMs and
environmental analysis indicate this will miss our area to the
southwest, moving from southeastern Nebraska into northwestern
Missouri, though the northern fringes of convection or
stratiform rain will likely clip far southern Iowa. Showers and
perhaps a few storms will spread across northern Iowa tonight
in closer proximity to the shortwave impulse, while between a
relative gap of sprinkles/light showers may affect much of
central Iowa. As a result high POPs around 60 to 80 percent are
carried in our far southwestern/southern counties, with moderate
POPs around 40 to 50 POPs in our far northern/northeastern
counties and lower 20 to 30 POPs in between. However, outside of
perhaps the far southwest corner, severe or impactful weather is
unlikely before the rain finally clears to the east on Saturday
morning. Did prolong POPs a bit after 12Z due to a slower
progression of the system.

This weekend a larger surface high pressure area will build
across the region, initially just to our west on Saturday and
then over Iowa Saturday night into Sunday. A weaker impulse will
move overhead during the day Saturday and into the evening,
however once again low-level subsidence around the building high
should limit any rainfall potential, with perhaps a few
sprinkles or showers but confidence/coverage so low as to
preclude POPs at this time. It is possible low POPs may need to
be introduced tonight or tomorrow, however any amounts or
impacts would be essentially nil. Meanwhile, the passage of this
second high pressure area will keep things relatively
comfortable through the weekend, with daily highs generally in
the 70s to lower 80s and dewpoints on Sunday remaining in the
upper 40s to lower 50s during the day. Nice.

Dry and pleasant conditions will continue into early next week,
with a mid/upper level ridge moving over on Monday. However, a
change is then on the way as a 500 mb trough/low moves eastward
over North Dakota and Minnesota on Tuesday, then a large heat
dome builds over the southwestern U.S. and into the High Plains
toward the latter half of next week. We will likely see a return
of shower and thunderstorm chances around Tuesday as the
northern trough moves by, but severe chances are low with
limited instability and shear. From Wednesday through the
remainder of next week as the southwestern heat dome builds in
we will remain near its northern periphery and may be impacted
at times by impulses rounding the top and producing rounds of
thunderstorms, however, at this range any such impulses are
notoriously difficult to predict and these details of the
forecast remain unknown as a result. What can be said with some
confidence is that a general warming trend is on tap during the
latter half of next week, with highs in the 80s becoming
increasingly likely during that time and the potential for some
areas to hit 90 degrees on one or more days.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1229 PM CDT Fri Jun 7 2024

VFR conditions are forecast for the next six hours, then
tonight -SHRA and perhaps isolated TSRA will move through the
area and may impact some terminals at times but with
confidence/duration too low for more than VC wording at this
range. Also a likelihood of low ceilings on Saturday morning,
with MVFR probable and IFR possible. Conditions should then
gradually improve by Saturday afternoon, near or after the end
of the current 18Z TAFs.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

DISCUSSION...Lee
AVIATION...Lee