Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 131119
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
619 AM CDT Wed Mar 13 2024

.KEY MESSAGES...

- Showers and thunderstorms expected Wednesday into Thursday,
  with a 5-15% chance for severe storms Wednesday night.

- Cooler, dry weather expected going from the weekend into
  early next week.

&&

.DISCUSSION...
Issued at 206 AM CDT Wed Mar 13 2024

Short Range (Today & Thursday)

An upper level trough is building into the western CONUS with a
shortwave trough ejecting out of southeast Colorado. This has
prompted a surface low to spin up near the CO/NM/OK border. The
surface low will be slow to move northeast across Kansas throughout
the day. An associated warm front currently draped across southern
Kansas will push northward throughout the day. Guidance is
suggesting the front will reach near the eastern NE/KS border by the
late afternoon/early evening. Strong low-level moisture advection
will bring southeast NE & southwest IA dewpoints into the mid 50s by
late afternoon with high temperatures expected in the low 70s.

The arrival of the surface low coincided with the warm front is
expected to prompt convective initiation along the eastern NE/KS
border around 7-9 PM this evening. CAM guidance suggests storms will
initially develop as isolated thunderstorms with supercells
possible. Both the HREF & HRRR indicate MUCAPE values of 1000-1500
J/kg in this area. Steep mid-level lapse rates (7-7.5 C/km) will
bring the potential of large hail to any organized thunderstorms.
The other primary hazard for this event will be strong winds. The
greatest risk for these potential hazards remains south of
Interstate-80 at this time.

Upscale growth and increased storm coverage is expected later in the
evening as the LLJ ramps up. This will bring a weakening trend to
any pre-existing severe thunderstorms. Coverage will progressively
push northward late Wednesday into Thursday as the surface low moves
into southwest IA.

Showers will persist throughout the day Thursday as the surface low
slowly drags eastward across Iowa. Strong northerly surface winds
will push into northeast NE during the afternoon, bringing high
temperatures into the 50s with values increasing to the 60s as your
progress southeastward. Similarly to Wednesday, low-level
convergence near the surface low and warm front is expected to
initiate severe thunderstorms in the warm sector across south-
central Iowa Thursday afternoon. These storms may initiate in our
southeastern counties (hence the marginal risk from the Storm
Prediction Center overlapping this area) before quickly exiting
eastward.

Precipitation is expected to wrap up late Thursday into Friday
morning. Total rainfall amounts are expected to range between 0.25
and 1" across the area. The highest totals are expected with the
overnight Wednesday into Thursday showers. Latest guidance has
suggested a shift in the heaviest rainfall towards east central NE
and west central IA, a southward trend from previous guidance. The
Weather Prediction Center has also issued a marginal risk for
excessive rainfall on Wednesday. A close eye will have to kept on
locally heavy rainfall associated with the initial thunderstorm
development across southeast NE and southwest IA.

Long Range (Friday-Tuesday)

Dry conditions will return on Friday as northerly low-level flow
will bring highs into the 50s, near average for mid-March. A brief
period of zonal flow will return on Saturday, bumping highs into the
60s. Sunday and Monday will see high temperatures drop into the 40s,
below average for this time of year, as a cold front and strong
northwesterly flow will move into the area. An eye will have to be
kept on elevated fire weather concerns this weekend as strong
surface winds and minimum relative humidity values of 25-35% are
expected. No additional precipitation chances are currently present
in the long range forecast.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 615 AM CDT Wed Mar 13 2024

Starting out with VFR conditions and light winds out of the
southeast. Forecasting increasing clouds and slowly lowering
cigs through the day with rain showers and thunderstorms
possible after 7pm this evening. Winds become northerly around
the same time.

Have left thunder out of TAFs for now, but it may be added as
timing and location confidence increases. Expect to see some
MVFR cigs and perhaps reduced vis (5 to 6 SM) by sunrise
Thursday morning but haven`t yet included in TAF due to low
confidence.

&&

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

&&

$$

DISCUSSION...Wood
AVIATION...Nicolaisen


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