128
FXUS63 KOAX 121742
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1242 PM CDT Wed Jun 12 2024

.KEY MESSAGES...

- Staying warm into next week. Heat index values could approach
  or exceed 100 in at least parts of the area this afternoon,
  Thursday, Sunday, and Monday.

- Our next chances for stronger to severe storms arrive this
  afternoon/evening (northeast Nebraska) and Thursday
  afternoon/evening (southeast Nebraska and southwest Iowa).

- Details remain unclear, but we`ll have daily storm chances
  Friday into next week with potential for strong to severe
  storms at times.

&&

.DISCUSSION...
Issued at 335 AM CDT Wed Jun 12 2024

Today and Tomorrow:

Water vapor imagery this morning features zonal flow aloft, with a
cutoff low continuing to spin off the California/Baja coast, small
shortwave impulses departing the far northern High Plains, and a
broad shortwave lingering in the TX/LA/MS/AR region. Looking at
a recent surface analysis of the local area, there is a wide
variance in surface moisture across eastern Nebraska with a 51
degree dewpoint in Norfolk while Lincoln and Millard read 60
degrees, in addition to another dry pocket to the south in
central Kansas. This dryness could negatively influence storm
potential this afternoon/evening, which is the primary focus of
the short-term forecast. Looking at regional radar, elevated
convection is beginning to initiate in central South Dakota
where warm air advection and low-level jet nosing provide just
enough lift. Those storms should waft east-southeast through the
morning and could potentially clip northeast Nebraska with some
light rain and rumbles of thunder but will largely remain
north.

For the afternoon hours, windy conditions and some of the
warmest temperatures of the year are expected to develop across
with the hot spot being far northeast Nebraska in Knox and
Cedar Counties (topping out in the upper 90s to near 100
degrees). Alongside the heat, storm chances redevelop this
afternoon as strong warm air advection tries to overpower dry
air -- a problem that is exacerbated by such warm temperatures.
Latest runs of the CAMs have a split decision on storm
initiation, with the RAP/HRRR (which currently have the best F00
hold on the direr surface dewpoints) showing little to no
activity aside from a stray elevated storm after 7 PM, while the
ARWs and NAMNest showing a southward moving cluster of storms
beginning 4 PM. These storms regardless should remain largely
elevated and have threats of damaging wind and hail based on the
abundance of instability and shear. Timing for storms will
generally be from 4 PM to 10 PM, with a 30% chance of occurring
(meaning most stay dry).

For Thursday, a weak front that will have dove in from the northwest
will have found itself in the southeast Nebraska/northeast Kansas
area, extending east-northeast. In the vicinity of this front, the
oppressive temperatures will have shifted to from the high point in
northeast Nebraska to Falls City and areas along the NE/KS
border. Fortunately, lower relative humidity values will mean
that heat indices don`t reach too far above forecasted
temperatures. As far as storm chances go, it continues to look
like the main axis of instability will reside south of the area,
and that while convection could initiate in eastern Nebraska
and Iowa, it will be a short affair before it quickly shifts to
Kansas and Missouri. Overall storm chances currently max out at
around 30% in far southeast Nebraska, making it a second day in
a row where most stay dry despite the storm potential. Storms
that do form would have the primary hazards of hail and wind
once again.

Friday and Saturday:

Going into the weekend, we`ll keep the trend of storm chances going
with thankfully lower temperatures set for Friday ranging
generally in the mid-to-upper 80s. An approaching shortwave
trough will have made it to the central High Plains to kick off
an organized MCS in the northeast CO/northwest KS/western NE
area. This cluster of storms is expected to travel eastward
bringing better chances for showers and storms to the forecast
area late in the evening into the overnight hours. Severe
potential will be limited locally by limited instability as the
MCS moves eastward, but some stronger wind gusts may make it to
eastern Nebraska. By Saturday, the main forcing that kicked of
the Friday MCS will have wafted eastward, bringing a warm front
northeast through the forecast area. Widespread shower and storm
chances are expected, lingering through much of the day with
what could be potential for a severe storm or two (especially in
far northeast Nebraska where afternoon peak instability best
lines up with the lifting warm front).

Sunday and Beyond:

Rounding out the weekend into early next week, our mid/upper pattern
will shift from zonal to southwesterly flow. Some kind of front will
be perpetually in the vicinity of eastern Nebraska into Iowa,
serving as a focus for additional shower and storm activity (though
Monday currently looks mostly dry). Highs are expected to range from
the upper 80s to low 90s, making for typical summertime
temperatures. If there is something to look for during the extended
forecast, it`ll be the increasing potential for a deeper
shortwave/full-on trough to pivot eastward from the southwesterly
flow, providing a more dynamic system to the area compared to the
weaker forced setups that we`ve been seeing lately.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1237 PM CDT Wed Jun 12 2024

There are a couple of VCSH to OMA through 18Z, but likely
precipitation free after 18Z other than a very small chance for
a storm in the 01-04Z time frame. Do expect LLWS at LNK and OMA
for several hours with a sharp speed chance and some directional
change from surface into the 1500-2000 ft AGL level. Otherwise,
expect VFR conditions with wind changes through the TAF period.

&&

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

&&

$$

DISCUSSION...Petersen
AVIATION...Barjenbruch