149
FXUS63 KDMX 160816
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
316 AM CDT Thu May 16 2024

.KEY MESSAGES...

- Scattered showers and isolated storms ending east this
  morning.

- Warmer Friday into Saturday with highs into the 80s.

- Active pattern Sunday afternoon into early next week. Threat
  for severe weather and heavy rainfall may develop Sunday night
  and again Monday night into Tuesday, although specific
  details remain uncertain at this time.

&&

.DISCUSSION...
Issued at 316 AM CDT Thu May 16 2024

Weak convection continues across portions of north central into
northeast Iowa early this morning ahead of a weak boundary passing
into the state.  Otherwise, some patchy fog has developed ahead of
the boundary in portions of southern Iowa and this is likely to
persist in advance of the front through daybreak.  Otherwise, the
front advances eastward across much of the forecast area by midday
with increasing subsidence and drier air overspreading much of the
area.  The exception may be the far southeast where some
redevelopment occurs prior to frontal passage but any activity would
quickly exit the area into eastern Iowa.  Cold advection is most
pronounced across northern Iowa today but good mixing and some
sunshine should keep temperatures similar in most areas to
Wednesday`s highs or perhaps slightly warmer in the south where
the cold advection is much more negligible.

An upper trof across western Canada into the northwest United States
has a shortwave passing through the base on Friday into Saturday
over the northern US Rockies.  Warm advection ahead of this system
is expected to intensify across Iowa tonight into Friday with
increasing southerly surface flow.  Temperatures should respond in
kind by Friday afternoon as highs climb into the 80s over much of
the area with ample insolation through the day. As the upper system
pushes through North Dakota and Minnesota, it sends a boundary
across Iowa on Saturday.  Instability develops ahead of this front
by afternoon with MUCAPES in vicinity of 1500-1800 J/KG however
soundings indicate a decent cap is in place for much of the day.
Sufficient mechanical forcing near the front may be enough for a few
isolated storms during peak heating but it appears to remain limited
at this point.

Beyond this point, broad west to southwest flow develops across much
of the United States heading into next week. Both the GFS and Euro
indicate strong return flow on Sunday with moisture surging back
north into the state with increasing chances of storms by the
afternoon in the west.  Chances overspread much of the state into
Sunday night as the low level jet veers over Iowa.  Additional
convection seems likely on Monday into Tuesday as a surface wave
develops along a boundary in Kansas and moves northeast toward Iowa.
The threat for heavy rainfall is expected during this time along
with some potential for severe weather.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1200 AM CDT Thu May 16 2024

VFR conditions prevail across much of central Iowa with a few
MVFR conditions co-located with the locations of showers/storms.
First round has moved through the area with the second round
moving into northwest Iowa bringing some shower and storms into
areas north. Vicinity of storms only looks to impact KFOD early
in the period with otherwise shower mentions at northern sites
overnight and southern sites (KOTM) early Friday morning.
Guidance continues to suggest MVFR, locally IFR conditions to
move through the area early Friday morning but kept towards
higher end of guidance with overall probabilities for IFR fairly
low (isolated ~30-40%), but updates may be needed if conditions
exceed current expectations.

&&

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

&&

$$

DISCUSSION...Cogil
AVIATION...KCM