Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 240519
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1219 AM CDT Fri Mar 24 2017

.SHORT TERM...(tonight through Sunday)
Issued at 320 PM CDT Thu Mar 23 2017

Forecast concerns in the short term will be shower and
thunderstorms through Saturday with the slow moving storm system.
Where the best potential for severe weather is and what kind of
rainfall amounts may occur.

The KTOP/KOAX 12Z soundings from this morning showed moist
conditions through h7 with around 1 inch of pwat and steep 3-6km
lapse rates around 8 deg C/km.  H9 winds increased to around 45kts
during the morning and a pocket of strong 0-3km bulk shear across
northeast NE between 15Z and 18Z...and the lift ahead of the
elevated warm front likely helped spark the TSRA with hail that
quickly moved into SD. This initial wave of H7 warm air advection
continues to move into MN and IA this afternoon.

This afternoon...the latest subjective surface analysis has the
warm front lifting across the forecast area with showers and
thunderstorms ahead of it. There has been a lot of lightning with
the storms and even some grass fires, however not a lot of
precipitation. Temperatures south of the warm front have warmed
into the mid and upper 60s with dewpoints in the 50s.

The large mid-tropospheric trough over NV/CA is forecast to shift
toward the four-corners area then deepen over CO/wrn KS overnight
into a closed low...slowly tracking across Kansas.  Broad surface
low pressure over eastern Colorado further deepens tonight with a
cold front extending into central and northeast Nebraska.

The day1 severe weather outlook tornado probabilities extend from
central Nebraska into western Kansas south through the OK Panhandle
and the TX panhandle with an area of hail/wind outlook in this
similar area where thunderstorms will be more focused.  Broad upper
level divergence and warm air advection along with PWATs around an
inch to 1.25" are progged.

The combination of the the approach of the upper level trough/broad
upper level divergence/waa/mid-level frontogenesis have isolated to
scattered storms this afternoon...becoming more focused from western
Kansas into western and central Nebraska into northeast Nebraska
this evening and tonight where CAPES of 1000-2500 J/kg will be more
prevalent and 0-6km bulk shear is forecast to exceed 60kts. The
RAP/HRRR did not have a good handle on the morning convection and
started to pick up on the afternoon convection with the 16Z HRRR
The general trend is to increase precipitation coverage from
central Nebraska into northeast Nebraska this evening and
overnight. Will maintain highest pops in northeast Nebraska
through tonight and Friday morning. Another area of showers and
thunderstorms ahead of the dry slot develops from eastern
Oklahoma into eastern Kansas and western Missouri and should make
it into southern Iowa friday. In between, scattered
showers/thunderstorms will be possible. The day2 SPC outlook
brings the marginal risk toward FNB...however keeps the slight
risk generally from southeast KS into southwest MO. Rain/showers
will continue on the northwest side of the storm system across the
outlook area Friday night and Saturday with the slow-moving
system.

Related to the rainfall expected...trimmed back amounts somewhat
with general amounts of a tenth to 0.50 inch. Still have higher
amounts from .75 to 1.75 for parts of northeast Nebraska.

.LONG TERM...(Sunday night through Thursday)
Issued at 320 PM CDT Thu Mar 23 2017

Unsettled weather continues with more showers Sunday
night...Tuesday night-Thursday.  Highs mostly in the 50s and 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1213 AM CDT Fri Mar 24 2017

The cold front is through KOFK and MVFR and IFR ceilings will
start to impact the terminal by 10Z this morning, and should
continue through the end of the period. The cold front will move
through KOMA/KLNK by 18-20Z with the MVFR/IFR cigs to follow by
late afternoon. We will also see period of rain overnight and
through the day at KOFK. Although isolated showers are possible
overnight tonight at KOMA/KLNK, more steady rainfall will not
develop in these area until late Friday afternoon into Friday
evening. Although some thunder is possible Friday afternoon at
KOMA/KLNK, it appears that the chances are to low to currently
include in the TAFs.

&&

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

&&

$$

SHORT TERM...Zapotocny
LONG TERM...Zapotocny
AVIATION...Boustead



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