Area Forecast Discussion Issued by NWS Omaha/Valley, NE
000
FXUS63 KOAX 131749
AFDOAX
Area Forecast Discussion
National Weather Service Omaha/Valley NE
1249 PM 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 /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1243 PM CDT Wed Mar 13 2024
VFR conditions this afternoon with only high clouds across the
area. Winds will be increasing out of the east through the early
afternoon ahead of the system approaching from the southwest.
Storms will move in from the south this evening, reaching KLNK
around 03Z, KOMA around 05Z, and KOFK around 07Z. Lowest chance
of TSRA is probably at KOFK which will skirt the edge of the
line of storms. Expect an hour or two of MVFR conditions with
TSRA before rain becomes more showery and visibility improves.
Winds will be turning more northerly overnight tonight with on-
and-off showers continuing at the terminals. Models show a 60 to
80 percent chance of cigs lowering by Thursday morning to MVFR
and holding through the end of the TAF period.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Wood
AVIATION...McCoy