783
FXUS63 KOAX 162346
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
646 PM CDT Fri May 16 2025

.KEY MESSAGES...

- Widely scattered showers continue this afternoon, mainly over
  northeast Nebraska (20-60% chance). Showers end early this
  evening.

- High Wind Warning and Wind Advisory remain in effect for the forecast
  area until 9 pm tonight. Expect northwest 30 to 40 mph winds
  with gusts up to 60 mph at times before subsiding late
  tonight.

- Breezy winds linger early Saturday before subsiding by the afternoon
  with pleasant conditions expected. Several chances for
  showers and storms return Sunday night through Wednesday,
  potentially with heavy rain and severe weather.

&&

.DISCUSSION...
Issued at 323 PM CDT Fri May 16 2025

.SHORT TERM.../Today through Saturday Night/

1930z 500 mb RAP objective analysis shows the closed upper level low
located right over Minnesota. Two vorticity lobes are noted within
the flow: one associated with the main closed low over Minnesota
extending southwestward toward Nebraska, and the secondary lobe
across Kansas associated with a weak wave. This wave provided some
forcing to generate widely scattered showers this morning over our
far south with a few mPING reports of rain. This activity has
largely pushed east into central Iowa this afternoon, but we are
starting to see more widely scattered showers across northeast
Nebraska associated with the vorticity lobe from Minnesota and the
cyclonic wrap around flow. These showers will eventually dissipate
as we head into the early evening hours. PoPs are currently at 20 to
60%, with the highest chances in far northeast Nebraska.

The main concern today continues to be the strong environmental
winds. RAP sfc analysis shows an impressive 987 mb low associated
with the upper level disturbance based over west central Minnesota,
with a tight pressure gradient extending southwestward into a large
portion of the South Dakota, Iowa, and Nebraska area. 850 mb upper
air analysis shows a strong jet associated with the closed low
feature, with the strongest winds (50-55 kts) seen over northeast
Nebraska and slightly lower speeds (35-45) observed over the rest of
eastern Nebraska/western Iowa. BUFKIT soundings show growth of the
mixed layer anywhere from 850-700 mb across northeast Nebraska,
while areas farther south where some gaps in cloud cover are present
show a deeper mixed layer up to 650 mb in the late afternoon hours.
This will allow us to tap into the strong winds/jet aloft with
anywhere from 35-45 kts of momentum transfer occurring at the
surface. The tapping into this stronger sink of momentum coupled
with the tight pressure gradient will result in widespread sustained
northwest winds of 30 to 40 mph with gusts anywhere from 50 to 60
mph. So, have continued the midshift`s High Wind Warning over
northeast Nebraska and Wind Advisory for the rest of the CWA through
9 pm tonight. Localized visibility reductions due to blowing dust
remain possible, as do localized power outages and tree damage. The
scattered showers across the north may help drive some of the
aforementioned momentum downward as well. Winds will somewhat
relax late this evening into Saturday morning, but could still
see some breezy northwest winds of 15 to 25 mph, particularly
over northeast Nebraska.

Did lower highs from NBM guidance today to account for northwest
winds and cloud cover hindering daytime heating. Highs today will be
in the mid 50s north to mid 70s south. Lows tonight will be in the
40s.

Saturday will see the sfc low over Minnesota continue eastward
toward the Ontario/Great Lakes area, with sfc ridging moving in
behind the low. This will result in winds slowly relaxing during the
day with dry conditions expected. Highs will be in the upper 60s to
mid 70s with a few clouds. Lows Saturday night will be in the low to
mid 40s.

.LONG TERM.../Sunday through Thursday/

Flow aloft at 500 mb becomes southwesterly on Sunday as the
longwave trough over the Four Corners area ejects northeastward.
The wave will induce cyclogenesis, with a sfc low developing
over the eastern Colorado area and resultant warm front
extending eastward somewhere over the Kansas/Nebraska vicinity.
Forcing for ascent increases by Sunday evening as the mid level
wave approaches the Central/Northern Plains. Dew points in the
low to mid 60s also arrive within the warm sector aided by
1000-850 mb moisture transport from the Gulf. With CAPE anywhere
from a few hundred to thousand J/kg and 0-6 km bulk shear
around 50-60 kts, these ingredients will support severe weather
across portions of the Central/Northern Plains Sunday evening,
with the Storm Prediction Center highlighting mainly south of
Interstate 80 in a slight risk of severe weather, while an
enhanced risk is seen just south of the border into Kansas.

One of the big questions that remains is where the baroclinic
zone/warm front will end up at. This will be extremely important in
determining where the better moisture and instability will be. GEFS
and Euro based ensembles still show considerable uncertainty in the
location of the sfc low center. Regardless of where the severe
threat ends up happening, we will still see some scattered showers
and thunderstorms, as the NBM currently has a 70 to 90% chance of
PoPs Sunday evening through early Monday morning.

Sfc low will continue to track to the northeast Monday, but still
seeing several discrepancies on where the sfc low and its
associated baroclinic zones/fronts will set up. Again, this will
have important implications on where we could see severe
weather this day, but the Storm Prediction Center currently
highlights portions of the forecast area in a 15% risk for
severe weather. NBM currently has a 70-90% chance of scattered
showers and storms areawide Monday night lingering into Tuesday.
PoPs decrease on Wednesday as the system finally exits the area
with dry conditions anticipated per NBM guidance on Thursday.

With several chances for showers and storms to start the work week,
this certainly leads to some concern regarding flooding potential.
Admittedly, what leads to some uncertainty regarding flood potential
is our current drought conditions. The majority of eastern Nebraska
is in a moderate to severe drought, while southwest Iowa is
abnormally dry to in a moderate drought. While there is still some
uncertainty with these upcoming waves/disturbances regarding timing
and location, do see at times deterministic PWATs up to 1.5 inches
across our far south and into southwest Iowa. With warm cloud depths
between 3,500 to 4,000 meters, these ingredients indicate efficient
rainfall production could occur. Ensemble members of the GEFS, Euro,
and Canadian show the best PWAT values (anywhere from 1.2 to 1.7
inches) arriving sometime early Monday morning through about early
Tuesday morning.

Again, lots of uncertainty exists at this point in the extended
forecast as the evolution of the upper level features will influence
how the sfc low tracks and where its baroclinic zones set up. We
recommend you continue to stay tuned to the forecast for the latest
updates regarding the severe and heavy rainfall potential for the
Sunday through early Wednesday systems.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 644 PM CDT Fri May 16 2025

Light shower activity is quickly dissipating and the remainder
of the TAF period should be dry. Strong northwesterly winds
continue across the area this evening, but speeds are are on the
decline. Expect that trend to continue over the next 24 hours.
Low VFR cigs are draped across the forecast are tonight and may
dip into MVFR categories just before sunrise Saturday morning
before improving by mid-morning.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Wind Advisory until 9 PM CDT this evening for NEZ045-050>053-
     065>068-078-088>093.
     High Wind Warning until 9 PM CDT this evening for NEZ011-012-
     015>018-030>034-042>044.
IA...Wind Advisory until 9 PM CDT this evening for IAZ043-055-056-
     069-079-080-090-091.

&&

$$

DISCUSSION...Castillo
AVIATION...Nicolaisen