123
FXUS63 KDMX 100437
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1137 PM CDT Thu May 9 2024

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

.KEY MESSAGES...

- Lingering shower chances into this evening, mainly along and
  east of I-35. Few showers/storms possible again Friday
  afternoon and evening.

- Fantastic spring conditions Saturday. Sunshine and 70s.

- Chances for showers and storms return early next week. Severe
  threat low.

&&

.DISCUSSION...
Issued at 200 PM CDT Thu May 9 2024

The presence of a broad, decaying trough overhead has sustained
shower activity over the forecast area through the day. The focus
has generally been within a diffuse zone of low level convergence co-
located with mid-level fgen forcing. RAP analysis shows pockets of 0-
3km CAPE pushing 100 J/kg beneath a cool airmass aloft. The enhanced
stretching potential combined with high background vorticity may
support a few funnels or brief landspouts. Dry air has really eaten
into the westward extent of the precip, much more so than suggested
by hires guidance. Thus the rest of the day has trended drier at
many locations, save for about the eastern third of the cwa which
stands the highest chance to see additional measurable
precipitation before the rainfall exits tonight.

Additional precip chances return Friday afternoon and evening
as a compact shortwave slides through the Great Lakes region and
sweeps a surface frontal boundary across the state. Synoptic
forcing contributions are not well phased on the south/west
periphery of the wave, and combined with dry boundary layer
conditions should limit the spatial coverage and depth of the
convection. Soundings show inverted-v profiles and steep low
level lapse rates up to ~800mb so a few brief elevated wind
gusts are possible, but overall the threat of any strong to
severe convection is low.

Make plans to get outside on Saturday as fantastic spring conditions
are forecast. A passing surface ridge axis beneath building heights
aloft will lead to dry conditions and subsidence through much of the
atmospheric column, giving way to plentiful sunshine and highs in
the 70s. Rain chances return early next week as cutoff upper low is
kicked out of the Four Corners region. Forcing mechanisms and
convergence still look rather diffuse, so it is difficult to
pinpoint a particular period for higher PoPs or to provide more
detail on potential precip amounts. The deterministic EC is
also more aggressive with impinging dry air on the northern
periphery of the upper low as it crosses the central Plains, a
trend that is also reflected in the EC ENS guidance with a fair
share of members now advertising no QPF over the northern half
of the forecast area. Flow aloft is very lethargic with 500mb
winds less than 20 kts. Any convection will be highly
disorganized and likely pose little severe threat.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1137 PM CDT Thu May 9 2024

A few lingering showers southeast through 08z with patchy fog
developing. FOD has already dropped to 1/4sm and expect MCW and
ALO to drop to 1 to 3sm by 10z, lifting around 13z. A few light
showers will move into the region aft 20z, but coverage remains
uncertain. Aft fog lifts, expect a VFR cig for all sites Friday.
/rev

&&

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

&&

$$

DISCUSSION...Martin
AVIATION...REV