Area Forecast Discussion
Issued by NWS North Platte, NE

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410
FXUS63 KLBF 290501 AAB
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1201 AM CDT Thu Jun 29 2017

.SHORT TERM...(This evening through Thursday)
Issued at 320 PM CDT Wed Jun 28 2017

There is reasonable agreement in the models that a developing 700mb
warm will be the catalyst for thunderstorms across Swrn Neb tonight.
The RAP and HRRR are honing in on the Srn Sandhills and Swrn Neb.
The RAP shows about 2000 j/kg of elevated 750mb computed CAPE just
south of Interstate 80 around 08z-11z.

The on-going jet streak across Nrn Colo and daytime heating appear
to be the genesis for front range thunderstorm development this
afternoon which should intersect the front as they move east this
evening.

There is also a disturbance moving across the Tetons which should
spark storms off the Big Horns. This appears to grow weakly upscale
this evening across Wrn SD which could affect Nrn Neb overnight.

Lastly, some level of storm development is expected on the Laramie
Range which could also move east and affect the Sandhills.

Thus, except for Swrn Neb, fairly disorganized thunderstorm
development is expected tonight.

The model consensus is in excellent agreement Thursday showing a
portion of the upper low across Canada translating east and
southeast through the Dakotas. This would support some sort of
scattered thunderstorm coverage Thursday across Ncntl Neb.

The severe weather potential Thursday hinges on the position of the
aforementioned h700mb front. If the front remains north during the
peak heating period, then severe weather could develop. The blend of
guidance plus bias correction holds the front along Interstate 80
Thursday.

The rain chance Thursday reflects the GFS with higher POPs north of
the 700mb front across Ncntl Neb. Confidence in the forecast
Thursday is below average because of the potential after-effects of
thunderstorms tonight across Swrn and Ncntl Neb. The front could get
held up across KS and never reach Swrn Neb.

.LONG TERM...(Thursday night through Wednesday)
Issued at 320 PM CDT Wed Jun 28 2017

Thunderstorm chances, likely across Ncntl Neb, are still in place
Sunday and Sunday night. The model consensus suggests a westerly
midlevel disturbance will move through Wyoming and catalyze a round
of storms originating off the Black Hills Sunday afternoon. This
would carve through Nrn and Cntl Neb Sunday night. The GFS indicates
about 3000 J/KG of MLCAPE and a 12-14C 700mb nose of warm air
advection edging into Swrn Neb.

Instability increases Monday but the shear weakens as h500mb winds
decrease from 40 kt Sunday to 30 kt Monday. POPs Monday are isolated
for this forecast.

No other significant rain chances are expected at this time as
either instability is limited, Friday and Saturday, or 500mb heights
amplify and ridge which should stabilize lapse rates.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1200 AM CDT Thu Jun 29 2017

Scattered thunderstorms will continue to move to the east across
western Nebraska through the early morning on Thursday. Winds in the
vicinity of thunderstorms VRB20G35KT. Some MVFR ceilings associated
with the thunderstorms but VFR with ceilings AOA BKN110. Northwest
winds will increase through the day on Thursday.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Power



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