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000
FXUS63 KDMX 211720
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1220 PM CDT Sun Apr 21 2024

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Sunny today with warmer temperatures, some frost/freeze
  potential remains tonight.

- Warmer and breezy Monday with scattered showers afternoon and
  evening.  Cooler into Tuesday and Wednesday.

- Increasing threat of impactful weather Thursday night into
  next weekend including strong to severe storms and locally
  heavy rainfall.

&&

.DISCUSSION...
Issued at 326 AM CDT Sun Apr 21 2024

|Ample clear skies and lighter winds overnight have allowed
temperatures top slip below freezing over much of the area early
this morning and headlines have this well covered.  Temperatures
should rise rather nicely after sunrise given the dry air and
increasing mixing.  The threat for some frost remains into tonight,
mainly in the east where winds become light enough for temperatures
to approach freezing.  However, southwest winds increase later
tonight from west to east with the departure of the surface
ridge along with increasing warm advection. One last headline
may be needed primarily in the east tonight and will let
dayshift reevaluate.

The broad west northwest flow persist into the early part of the
upcoming work week with another shortwave dropping from Canada into
the northern Midwest on Monday into Tuesday.  Strong warm advection
is expected into Monday ahead of the cold front across Iowa with
temperatures rebounding well into the 60s and even some 70s in the
west.  A narrow ribbon of moisture slides northward ahead of the
advancing front but in general, moisture is somewhat limited with
this system.  Scattered coverage (30-40%) of showers and perhaps and
isolated (10-20%) thunderstorm are expected in the narrow moisture
corridor coincident with the boundary by Monday afternoon, primarily
in the northern half of Iowa nearest the deeper lift.  The threat
shifts southward into Tuesday evening as the boundary settles into
southern Iowa although areal coverage remains scattered at best with
the limited moisture.

Cold advection intensifies into Tuesday as the upper trof passes
across Iowa with relatively robust northwest winds expected.  Low
level instability develops across the northeast by midday with some
a few showers possible with drier conditions farther southwest.
Otherwise, quiet weather is likely into Wednesday as surface ridging
passes and weak warm advection commences.

A rather significant change in the pattern occurs into the later
half of the work week as western troughiness develops.  Initial
shortwave comes ashore across southern California before rapidly
ejecting northeast into the central United State Thursday night into
Friday.  The low level jet strengthens across the Plains to 50kts+
on Thursday night with impressive theta-e advection impinging on
Iowa late.  This is likely to produce widespread thunderstorm
activity late Thursday night into Friday morning with some severe
threat possible.  The surface low passes through Iowa on Friday with
some redevelopment expected with peak heating and with potential for
severe storms remaining.  The pattern remains active into next
weekend as strong southwest upper flow maintains across the central
United States with ample moisture streaming into the region and the
threat for additional rounds of convection.  Details will be
forthcoming as the timeframe approaches.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1220 PM CDT Sun Apr 21 2024

VFR conditions through the period. Main concern continues mixing
winds this afternoon through 00z with gusts nearing 20kts.
Overnight winds swing around to the southwest and increase aft
14z...gusts nearing 25 to 30kts by end of period. Next package
will outline timing/coverage of showers toward 00z. /rev

&&

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

&&

$$

DISCUSSION...REV
AVIATION...Cogil