Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 231137
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
637 AM CDT MON MAY 23 2016

.SHORT TERM...(Today through Wednesday)
Issued at 1252 AM CDT Mon May 23 2016

8Z subjective surface analysis indicates a cold front situated
along a line from KONL to KEAR to KHYS. Temperatures were quite
mild with many places reporting around 70 degrees, nearly 15
degrees above normal. A line of showers and thunderstorms have
migrated into northeast Nebraska but are losing their surface
based characteristics virtually ruling out any severe weather
threat early this morning. Expect this line of showers and
thunderstorms to continue to diminish this morning as it waddles
east.

Aloft broad southwesterly flow was noted ahead of an upper level
western conus trough. This trough, as it shifts east, will be a
major weather maker for our area by the end of the work week and
looks to dominate our weather into the weekend.

New precipitation development is expected later this morning and
into the afternoon ahead of a weak shortwave progged to pass
through this evening. Overall severe weather parameters aren`t
great, but can`t rule out stronger storms as the atmosphere
destabilizes this afternoon. The severe weather threat continues
into Tuesday as a more prominent shortwave moves through. For
Tuesday it`ll be a question of timing and if the shortwave timing
coincides with peak heating, which could very well place the
better severe weather threat further west towards Hastings and
Kearney. On Wednesday we should see a break, albeit a short one,
in the precipitation chances as the boundary layer dries out.

.LONG TERM...(Wednesday night through Sunday)
Issued at 1252 AM CDT Mon May 23 2016

An unsettled weather pattern is expected through this period as
broad southwesterly mid-level flow dominates ahead of the main
system by Friday.

To start Wednesday evening some low-level drying continues from
earlier in the day allowing for a continued break in
precipitation. By late in the evening the first of a couple of
shortwaves propagate through, potentially bringing a return of
precipitation as well. Guidance differs a bit on the location and
track of these features. Overall confidence in Wednesday night
precipitation isn`t very high as a result.

Thursday evening marks the beginning of the period where we could
see the best heavy rain potential. Recent guidance suggests areas
along the Nebraska/Kansas border and into southwest Iowa will be
under the gun for the heaviest rain. Model predicted precipitable
water, which tends to be overestimated, is around 1.6 inches in
these areas Thursday night. If this were to verify it would be a
near record value based on past data collected at the Omaha NWS
office. Thursday night will need to be watched for a potential
flash flood watch, especially given some rain, possibly heavy,
will have fallen in the days prior.

By late Friday morning the heavy rain pushes east into central
and eastern Iowa as the main upper low traverses the forecast
area. As this and the corresponding surface low track through the
central Plains, the chance for severe weather on Friday seems
increasingly likely. At the moment the better potential would be
south into Kansas, but our area will need to be monitored.
Thereafter remnant southwesterly flow along with modest available
moisture will allow for precipitation chances through Sunday.

&&

.AVIATION...(12Z TAFS for KOMA...KLNK...KOFK through 12Z Tuesday)
Issued at 621 AM CDT Mon May 23 2016

A complex weather scenario has unfolded this morning due to the steady
weakening of a linear convective system as it entered our
northwest CWA. This has created considerable uncertainty in the
evolution of subsequent convection today. Recent trends in radar
data indicate showers beginning to develop across eastern Nebraska
and southwest Iowa, which are not well resolved by current near-
term model guidance. As such, we will maintain VFR conditions, but
include TEMPO groups for MVFR ceilings and visibility due to
thunderstorms this morning. The cold front will stall over
northeast Nebraska this afternoon with potentially variable wind
directions at KOFK. Specific timing and location of convection
east of the front this afternoon into tonight remains highly
uncertain, so we will only include PROB30 groups at KOMA and KLNK.
We could also see some reduced visibilities in fog later tonight,
especially at KOMA and KLNK.

&&

.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&

$$

SHORT TERM...Pearson
LONG TERM...Pearson
AVIATION...Mead



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