Flash Flood Warning 37, NWS Omaha, NE

Area Forecast Discussion
National Weather Service Omaha/Valley NE
619 AM CDT Fri Jul 19 2024

.KEY MESSAGES...

- An extended stretch of cooler-than-average temperatures will
  persist into next week.

- Widespread rain chances will be Friday evening into Sunday.
  There are additional spotty rain chances into next week.

&&

.DISCUSSION...
Issued at 444 AM CDT Fri Jul 19 2024

Temperatures have slipped into the 50s and 60s across the area
this morning with light southerly winds. Upper air analysis
shows a ridge over the Four Corners area separating two
distinct trofs. This omega blocking pattern will remain through
the 7 day forecast leaving northwesterly flow the dominating
factor in a cool forecast for Nebraska and Iowa.

KOAX / KFSD reveals some pulse looking storms just west of
Niobrara, NE. These are likely in response to the WAA at the
nose of the nocturnal jet. With 50dBz returns up to 20,000
feet, I'd expect at least a chance of some pea sized hail.

The HRRR is notably dry this morning, but other HiRes models
suggest convection could make it close to Lincoln, before
lunch. Storms should remain sub-severe.

Storms may become more powerful this afternoon with a "marginal"
severe weather category draped over areas west of a line from
Yankton to Norfolk to Columbus to York. Better chances of severe
weather are painted across central Nebraska. CAPE peaks at
under 2,000 J/kg along with plentiful shear of 30-50 knots
difference between 0km and 6km. Weak southerly surface flow
will find itself under a jet streak producing 40-50 knot north-
northwesterly winds.

Damaging winds should be the greatest threat as storms grow into
bowing lines. The HRRR currently keeps the best chance for
flipped center pivots west of the forecast area.

Forecast highs of lower to mid-80s may actually leave the day as
the warmest of the following few. Elevated smoke from the West
Coast and western Canada should produce some milky skies peeking
from behind partial cloud cover. It'll nerf the power of what
little July sun we receive.

.SATURDAY...

Saturday morning represents the forecast's best chance of rain.
It's worth noting that WPC has forecast a marginal chance of
flash flooding. Most locations will see less than an inch, but
localized probability matched mean (HREF LPMM) suggests 2-4" is
possible in localized areas.

High temps will be only in the lower to mid-70s. In July. I can
only find one late-July day in the past ten years that didn't
manage at least 75 in Omaha (7/15/16).

.SUNDAY AND NEXT WEEK...

More showers (30-50%) are possible on Sunday with the passage of
a mid-level shortwave. Under the overcast skies, temps again
will fall shy of 80 degrees.

The blocking pattern is expected to change little over the next
week, leaving temps shy of seasonal norms. Both the 00Z GFS and
00Z Euro suggest the blocking pattern breaking down as we
approach next weekend. This may bring increasing temps and a dry
period over the week's second half.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 617 AM CDT Fri Jul 19 2024

Thunderstorms in northeast NE have been near KOFK, but will
likely be southeast of that TAF location by TAF issuance.
Otherwise, additional thunderstorms will be possible at KOFK
20-24z, and at KLNK/KOMA 23-02z. Southerly winds 7-9 knots
increasing to 12-21 knots by 16-17z, then below 12 knots beyond
then. And finally, MVFR ceilings could move into the KOFK area
later in the TAF by 20/07z.

&&

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

&&

DISCUSSION...Nicolaisen
AVIATION...

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