297
FXUS63 KOAX 291114
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
614 AM CDT Mon Apr 29 2024

.KEY MESSAGES...

- Quiet weather is expected today, letting the area catch
  its collective breath.

- Showers and storms return Tuesday afternoon, with a 15-30%
  chance of severe storms. Large hail and damaging winds are
  the primary threats, but tornadoes cannot be ruled out.

- Storms redevelop Wednesday and linger into Thursday,
  with potential for severe storms once again. In addition,
  prolonged rainfall could lead to flooding.

&&

.DISCUSSION...
Issued at 339 AM CDT Mon Apr 29 2024

Early morning analysis showed a surface low spinning over
southwest MN, ushering in some clouds into the northern half of
the forecast area. There were perhaps a few spotty sprinkles,
but overall it was very quiet overnight. The quiet weather will
continue today as the low pushes to the northeast and any
remaining clouds exit the area. Temperatures will be right
around average for this time of year, with highs in the mid 60s
to lower 70s.

Unfortunately the quiet weather doesn`t last long, as storm
chances return Tuesday through Thursday. First on Tuesday, a
shortwave currently off the Pacific Northwest coast will slide
eastward into the Dakotas, along with a surface low. This will
induce strengthening southerly low level flow in our area during
the day, bringing in some warmer air (highs generally in the
mid 70s to mid 80s) and a little moisture, with dewpoints in the
mid 50s to around 60. However, still some questions on moisture
depth and just how far north it will make it before the wave
and a surface cold front start to slide through and lead to
storm development. Initial development looks to be across
southern SD into north-central/northeast NE (closer to the
stronger forcing with the shortwave) by late morning or early
afternoon with additional storms forming south-southwest along
the front as we go through the afternoon. 29.00Z HREF guidance
suggests SBCAPE values around 1500 J/kg into northeast NE,
though larger scale models are a little less aggressive. Still,
it should be good enough alone for at least some stronger storms
and will combine with sufficient deep layer shear for storm
organization, meaning severe weather is on the table. Currently
thinking we`ll see a large hail threat with any initial discrete
storms before the threat transitions to damaging winds as
storms organize into a line and push east. Latest guidance does
suggest some low level hodograph curvature, indicating some
tornado potential, but if moisture is limited, that potential
could remain on the lower side.

These storms should exit to the east by 8-9 PM or so giving way
to a quiet overnight. However, a larger scale trough will be
digging into the western CONUS, with additional shortwave
energy ejecting eastward and spinning up a surface low over
southeast CO, in turn pushing a west-east oriented warm front
northward into the forecast area by Wednesday afternoon. Expect
storm development in vicinity of this front with plenty of
instability and shear for large hail, damaging winds, and
tornadoes. In addition, could see prolonged, possibly heavy,
rainfall and a flooding risk along the front into Thursday given
precipitable water values in the 1.2 to 1.5 inch range and warm
cloud depths around 3500 m. The big question will be just how
far north the front makes it, with guidance still showing a fair
amount of spread in exactly where it sets up. That said,
general consensus would say somewhere between I-80 and the NE/KS
border.

Beyond Thursday, zonal flow sets up with hints at various weak
bits of shortwave energy sliding through and bringing additional
precip chances into the weekend, though confidence in exact
timing is low at this time. Otherwise, temperatures will remain
pretty consistently in the mid 60s to mid 70s through Sunday.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 609 AM CDT Mon Apr 29 2024

Patchy MVFR ceilings will continue to push east of the forecast
area today. KOMA and KOFK could briefly pop in and out of MVFR,
but anticipate VFR conditions prevailing for the majority of the
period. Winds will be out of the west at around 10-12 kts with
the occasional gust up to 18-20 kts. In the early afternoon
winds will weaken before shifting to the southeast after 00Z
this evening.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.

&&

$$

DISCUSSION...CA
AVIATION...KG