768
FXUS63 KOAX 272249
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
549 PM CDT Sat Apr 27 2024

.KEY MESSAGES...

- Severe thunderstorms Today and Saturday with strong tornadoes,
  large hail, damaging winds, and flash flooding possible.
  Greater flooding threat on Saturday night.

- Severe thunderstorms possible on Sunday as well, to a lesser
  degree, but brief tornadoes possible as well.

- Storms wrap up by Monday, with warmer temperatures arriving
  next week. Another round of showers and storms possible
  Tuesday/Wednesday.

&&

.DISCUSSION...
Issued at 139 PM CDT Sat Apr 27 2024

Today and Tomorrow:

As of 17z, water vapor imagery shows a deep trough pivoting across
the Southern Rockies, with a compact and mature system continuing to
move into the Great Lakes Region; sandwiching eastern Nebraska and
Iowa in between. At the surface, a deepening surface low is located
in southeast Kansas with a warm front extending northeast from it
into far northeast Kansas where dewpoints go quickly from the low
50s in southeast Nebraska to 68  degrees in Jackson County Kansas.
Storms are developing along this front in northeast Nebraska, with
further development expected to increase and lift northward as the
afternoon goes on. Effective shear goes from 40 kts or more to 20
kts two to three counties to the north, extending the severe threat
area north of the front, wherever it does lift. Deep shear vector
orientation continues to line up parallel with the warm front, with
very messy and clustered storm modes expected. With the prolonged
lift being applied to the area, multiple rounds of showers and
storms are expected to move through eastern Nebraska and
southwest Iowa into tomorrow. The combination of increased
column moisture and somewhat saturated soils from yesterday`s
activity will result in increased flooding risk in eastern
Nebraska and Iowa. Model QPF indicates that some spots may see
over 2.5", with the highest chances being along the warm front
and where it eventually lifts in southeast Nebraska.

The main hazards for the event continue to be damaging hail, wind,
flooding, and tornadoes with the highest threat for any tornadic
activity being the messy storm modes along and south of the warm
front. While the storm threat does decrease north of the warm front,
it`s not zero owing as far north as to the sufficient instability,
strong shear elevated instability that could help root storms close
enough to the surface still allow for all hazards as far north
as a line from Columbus to Tekamah. In between stronger storms,
scattered showers and weaker storms will continue with an
increasing threat of flooding into the overnight hours. Showers
and storms will be scoured out by around noon Sunday as the
main mid-wave and surface low moves through/to the southeast,
leaving us to catch our breath once again. Highs Sunday will
vary widely from the 50s in northeast Nebraska to low 70s in
southeast Nebraska and Iowa.

Monday and Beyond:

For the upcoming work week, increasing heights are forecast to
develop in the absence of weekend`s deep systems with the forecast
expected to stay busy as smaller and more compact waves move through
Tuesday, Wednesday to Friday, and then again possibly Sunday. Highs
will remain comfortable in the upper 60s to 70s with gusty winds
expected Tuesday.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1214 PM CDT Sat Apr 27 2024

Scattered showers are expected to persist along the I-80
corridor and slowly expand to the north. Though there will be
breaks in the rain, prevailing conditions should be light rain,
particularly at KLNK and KOMA through the forecast period.
Tonight, low stratus is expected to build into the region from
the northwest. Widespread IFR ceilings are expected, though
periodic dips into LIFR ceilings will be possible at all TAF
sites. Confidence and persistence at KOFK was enough to include
in TAFs. A few rumbles of thunder will also be possible, but
thunderstorm coverage tonight is not expected to be widespread.
Some guidance suggests patchy mist/drizzle which may bring
visibilities down to the 3 to 5 mile range tonight, particularly
across northeast Nebraska (KOFK). Confidence precludes inclusion
in TAFs at this time but will monitor for amendments.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flood Watch through Sunday afternoon for NEZ015>018-030>034-
     042>045-050>053-065>068-090>093.
IA...Flood Watch through Sunday afternoon for IAZ043-055-056-069-
     079-080-090-091.

&&

$$

DISCUSSION...Petersen
AVIATION...Darrah