929
FXUS63 KDMX 271129
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
629 AM CDT Fri Sep 27 2024

 ...Updated for the 12z Aviation Discussion...

.KEY MESSAGES...

- Mild, dry, quiet weather continues through Monday with little
  to no local effect from Helene.

- A cool front will push across Iowa around Monday night,
  bringing a brief but notably cooler period from Tuesday into
  Wednesday.

- No rain is forecast in the next seven days.

&&

.DISCUSSION...
Issued at 244 AM CDT Fri Sep 27 2024

Currently a large mid/upper low pressure center is located near
the Tennessee/Mississippi border, while Hurricane Helene is
moving from the Florida panhandle up into Georgia. These two
systems will rapidly coalesce into one large gyre by this
evening, then wobble nearly stationary over Kentucky and
surrounding states through the weekend. To the northwest, over
Iowa, ridging and subsidence will dominate leading to a
continuation of dry and quiet weather. We will see some high
clouds in our southeastern counties at times, on the fringes of
the large gyre, but otherwise no impacts are forecast. Given the
dry airmass in place we have been seeing high temperatures
overachieve relative to preceding guidance, and continued this
trend by raising forecast temperatures a degree or two for today
and Saturday.

On Monday an energetic trough will sweep across the northern
U.S., moving quickly from eastern Montana to northern Minnesota
during the day with its cyclonic influence helping to finally
sweep the remnants of the Helene system out into the
Appalachians. The surface front trailing from the northern
trough will push across Iowa around Monday night, bringing
notably cooler weather Tuesday with high temperatures in the mid
to upper 60s being about 15 degrees below Monday levels.
However, the cooldown will be short lived as the succeeding
surface high pressure area will scoot quickly across the region,
followed by a return of south/southwesterly low-level flow from
Wednesday through Friday and promoting at least modest warming.
Unfortunately there is no real sign of precipitation in Iowa on
the horizon, at least through the middle of next week and quite
possibly longer. Surface fuels are very dry and rapidly curing
so this may lead to slowly increasing fire weather concerns,
however, strong winds are not foreseen during daytime periods in
the current forecast so the threat will be mitigated for now.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 629 AM CDT Fri Sep 27 2024

VFR conditions are forecast through the TAF period with no
aviation impacts. Light and variable winds early this morning
will come around to NNE by midday and through tonight, staying
generally light except at OTM where gusts to 15-20 KT may be
seen infrequently this afternoon.

&&

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

&&

$$

DISCUSSION...Lee
AVIATION...Lee