Area Forecast Discussion
Issued by NWS North Platte, NE

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314
FXUS63 KLBF 301121 AAA
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
621 AM CDT SAT JUL 30 2016

.SHORT TERM...(Today and tonight)
Issued at 339 AM CDT Sat Jul 30 2016

Today and Tonight...the weather situation today and tonight is
similar to Friday with three rounds of convection. The ongoing
convection across Ncntl will dissipate this morning as the low level
jet weakens and lapse rates become less steep. This area of rain
formed as a result of the low level jet...an upper air disturbance
across SD and steepening lapse rates.

Satellite suggests a second area of steep lapse rates across Ern Wy
and the Neb panhandle. It is believed this area will drift east
today and become the focus for severe weather this afternoon. The
Black Hills would be the source area of storm development. The HRRR
and NAM suggest the White River Valley in SD as a source region. The
models show a plume of deep moisture moving up the Cntl High Plains
late this afternoon the forecast shades the better rain chances...30
percent along highway 61 and across the Ern Panhandle.

A modest 30kt low level jet will form tonight and the model
consensus suggests another round of thunderstorms will form across
Ncntl Neb as a result of lingering evening convection...the steep
lapse rates and forcing from the low level jet.

The temperature forecast uses a four-way blend of guidance plus bias
correction for highs in the 80s and lows in the 60s. Sfc dew points
will rise into the mid to upper 60s for humid conditions.

.LONG TERM...(Sunday through Friday)
Issued at 339 AM CDT Sat Jul 30 2016

Mid range-Sunday through Monday night: Right out of the gate, there
are some significant model differences between the 00z NAM12 and GFS
solutions tonight. First off, the NAM12 develops a MCS tomorrow
evening, pushing this feature to the southeast across the forecast
area Saturday night. The result is a frontal boundary which becomes
anchored along the KS/Nebr border Sunday into Monday. The GFS is
similar but weaker with the MCS and frontal boundary, lifting
washing this feature out Sunday night, allowing very warm air to
push into the forecast area for Monday. This shows up in the latest
statistical forecast guidance which has a 10 degree spread for highs
Monday with the GFS MAV guidance much warmer than the NAM MET
guidance. For highs on Monday, decided to weigh the forecast heavily
on the inherited forecast, weighted more toward the warmer MAV
guidance. That being said, decided to limit precipitation chances
for Sunday night confining them to the southwestern forecast area as
both the NAM and GFS solutions do have a surface boundary anchored
across southern Nebraska. Will confine the chances to the evening
hours as the GFS lifts the front north overnight. Shifting into
Monday, as mentioned above, there are some significant model
differences with respect to temperatures on Monday as well as the
threat for thunderstorms late Monday into Monday night. With the NAM
having a front anchored to the south of the forecast area, it
remains the coolest solution for highs Monday. It also generates
precipitation Monday night as a low level jet crosses perpendicular
to the frontal boundary. The GFS solution is drier and confines
precipitation chances to Monday night INVOF of an approaching
surface trough/weak frontal boundary. Will hold onto pops for Monday
night as there is some mid level warm air advection which over
spreads the front Monday Night. This warm air advection is
strongest in the east and that is where pops were retained.

Long range-Tuesday through Friday: A trough of low pressure aloft
will push onshore Tuesday which will amplify ridging downstream
across the central and northern plains. Much warmer air will flow
into the forecast area on Tuesday which will result in highs
reaching the mid to upper 90s. The ECMWF solution does hold onto
some cooler air and additional low level moisture for Tuesday, so
decided limit highs to the middle 90s. The next threat for pcpn in
the extended will arise on Wednesday night as a cold front passes
through the forecast area. Temperatures behind the front will be
in the 80s for Thursday and Friday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 619 AM CDT Sat Jul 30 2016

The thunderstorm activity across Ncntl Nebraska will decay this
morning with the loss of the low level jet...15z-17z.

New storm development is expected this aftn...21z-03z...across Wrn
Neb. Look for storms to develop off the Black Hills and move
southeast into Nrn Neb. There is also the threat of storm
development across the Nebraska panhandle directly.

Further storm development is expected 06z-12z tonight across Ncntl
Nebraska...along and east of highway 83 as the low level jet
restrengthens.

The SREF...NAM and ECM continue to show a high probability of MVFR
cigs tonight...from 06z onward. This ceiling is expected to form
along and south of nebraska highway 2.

&&

.LBF Watches/Warnings/Advisories...
None.
&&

$$

SHORT TERM...CDC
LONG TERM...Buttler
AVIATION...CDC



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