957
FXUS63 KOAX 271116
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
616 AM CDT Thu Jun 27 2024

.KEY MESSAGES...

- Moderate flooding is ongoing or expected to begin along the
  Missouri River the next day or two. It`s forecast to last into
  next week for Omaha and points south.

- Low chance of strong to severe storms Thursday night into
  Friday and a better chance Friday afternoon into Friday night.
  Both rounds of storms could produce heavy rain and localized
  flash flooding.

- Quiet and cooler for the weekend, with highs in the mid 70s to
  mid 80s. Then warming back up and becoming more active for the
  holiday week.

&&

.DISCUSSION...
Issued at 256 AM CDT Thu Jun 27 2024

A weak shortwave is generating light showers on radar over
northeast Nebraska this morning. Only trace accumulations have
been observed so far. More significant showers are out over
central Nebraska where the better moisture advection is
occurring with the low-level jet. This won`t migrate eastward
until this evening as a surface high remains in place over
eastern Nebraska through much of today.

Expect only isolated to scattered showers through this afternoon
with mostly cloudy skies keeping temperatures on the cooler
side. Highs today will only peak in the upper 70s to low 80s,
though if the sun does peek out we could gain a few extra
degrees this afternoon.

Tonight we`ll see the low-level jet shift eastward bringing the
axis of significant moisture advection into our area which will
ramp up shower and storm activity after 7 PM. This will also
dampen the environment out ahead of a cluster of stronger storms
that develop out over western Nebraska. We expect strong storms
to develop out over northeast Colorado or the Nebraska Panhandle
this afternoon and evolve into a convective complex that
progresses eastward overnight. As these strong storms move
toward our area, the worsening environment should weaken the
storms leading to a diminishing threat for severe weather. SPC
does have us in a Slight Risk for severe storms, but if it were
up to me I`d have us closer to 5 percent. CAMs support this as
well as the synoptic models.

The bigger concern overnight tonight will be for heavy rain as
PWAT values in the axis of moisture advection will get up to
around 1.8-2 inches. That is near the daily max in sounding
climatology for the area. This will mean showers and storms
will be very efficient rain producers, so any training of storms
could lead to quick accumulations of an inch or more of
rainfall. Flash flooding could become a concern. As of right now
the CAMs suggest showers should all keep moving, but this should
be monitored none-the-less, especially with rivers already
running high and the ground being fairly saturated.

Most of the shower and storm activity will move off to the east
Friday morning, but we`ll remain in unstable mid-level flow
regime through the day with warm, moist, unstable air continuing
to stream into the region from the south. Highs Friday afternoon
will get back up into the mid-to-upper 80s with dew points up
around 70 degrees, which will lead to significant afternoon
environmental surface-based instability. 35-45 kt of Effective
Bulk Shear and sufficient low-level shear will support the
development of supercells or strong convective clusters Friday
afternoon and evening with the potential for very large hail,
damaging winds, flash flooding, and a few tornadoes if we can
get a sustained supercell or two. The problem may be lack of any
cap which will lead to rapidly developing convective clusters
limiting the tornado potential. We`ll get a better idea from the
CAMs tomorrow for timing of convective initiation and convective
mode, so stay tuned. Friday afternoon-evening is the time period
to watch.

Saturday and Sunday we get a break in the storm chances just in
time for the weekend as high pressure dropping south out of
Canada builds across our area. This will bring in mild, dry
weather making for very pleasant weather this weekend. Our next
chance for rain comes with an upper-level trough bringing a
front through during the Sunday night-Monday timeframe. Another
stormy pattern looks to set up going into midweek next week just
in time for 4th of July celebrations.

Lastly, we all should continue to monitor the situation with our
ongoing flooding along the Missouri River basin. Additional
rainfall with the already swollen rivers may lead to additional
flooding on more rivers and/or extended flooding on the
Missouri longer than currently forecast.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 612 AM CDT Thu Jun 27 2024

VFR conditions are expected to prevail. Scattered light rain
showers and areas of virga are present across eastern Nebraska
this morning. Confidence is high that these showers will reach
KOFK and KOMA before clearing by 14-16Z. Southerly winds will
increase in speeds above 12 kts by 14-16Z and remain gusty
throughout the forecast period. Gusts up to 26 kts will be
possible. A round of showers and thunderstorms is expected to
reach the terminals late this evening. Confidence in the
impactful timeframe is low and will likely be adjusted with
future TAF issuances.


&&

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

&&

$$

DISCUSSION...McCoy
AVIATION...Wood