Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 260021 AAA

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
721 PM CDT MON JUL 25 2016

...Updated Aviation section...

Issued at 323 PM CDT Mon Jul 25 2016

H5 analysis this morning had a zonal pattern across the
northern third of the CONUS and southern Canada. High pressure was
anchored over the four corners with a second high noted off the
coast of the Carolinas. Some mid level disturbances were noted off
to the west of the central and northern Plains. Shortwaves were
noted across eastern Oregon and northern California. Current WV
imagery this afternoon has the Oregon shortwave over sern Montana
with the California shortwave now entering northwest Nevada. At the
surface, high pressure was present over eastern Nebraska. Southerly
flow has increased across the panhandle and the western sandhills
this afternoon. Skies were mostly clear with readings ranging from
83 at North Platte to 90 at Valentine.


.SHORT TERM...(This evening through Tuesday)
Issued at 323 PM CDT Mon Jul 25 2016

Tonight and Tuesday...Precipitation chances for tonight into
tomorrow are the main forecasting challenge. With the arrival of
this morning`s model runs, am much less optimistic about
precipitation than what was in the inherited forecast. A couple of
aspects which should confine convection to the far northwestern
forecast area are as follows: First the triggering shortwave is
not even expected to approach the western Dakotas till the late
evening/early overnight hours. Second the main instability axis is
across the western panhandle and actually retrogrades west into
eastern Wyoming this evening. Thoughts here are that any
convection which can develop in the higher terrain of eastern
Wyoming/Black Hills of South Dakota will have a hard time working
east of the instability axis, especially in western and north
central Nebraska. With this in mind, have confined pops to the far
northwestern CWA for tonight and have eliminated them from the
central and eastern forecast area. Overnight tonight, the
instability axis will begin to migrate east as high pressure works
east of Nebraska. Attm, not expecting much activity in the morning
with the exception of far northern portions of the forecast area
which may on the srn periphery of any MCS`s which develop and
track across South Dakota overnight tonight.

.LONG TERM...(Tuesday night through Monday)
Issued at 323 PM CDT Mon Jul 25 2016

Tuesday night through Thursday...Late Tuesday, surface
heating along with moisture advection will work into western and
central Nebraska during the afternoon hours. A nice axis of 3000-
4000 j/kg of CAPE develops along and west of highway 83, the nose of
this works into southwestern South Dakota by 21z Tuesday afternoon.
With the approach of a nice mid level shortwave timed to peak
heating, thunderstorms should initiate in southwestern South Dakota
and the northeastern panhandle around 21z. This activity will fill
into the southeast and will impact northern Nebraska by late
afternoon. Very favorable bulk shear should allow storms to turn
right into the instability axis Tuesday evening with the
precipitation threat extending to the southeast into most of western
and north central Nebraska. Northwesterly flow aloft will amplify
further on Wednesday with the NAM12 and GFS forcing a succession of
mid level disturbances across the high plains into central and
eastern portions of the forecast area Wednesday into Thursday.
Decided to hold onto slight and chance pops Weds through Thursday
periods as we hold onto abundant low level moisture during these
periods. This is further supported by the mav and met guidance which
does have some pops in the 20 to 40 percent range Weds aftn/weds
night. On Thursday, a stronger shortwave will drop south from North
Dakota into eastern South Dakota. This will force a cold front into
northern Nebraska Thursday afternoon-leading to another threat for
showers and thunderstorms.

Friday through Monday...After cooler temperatures behind the
front Friday, temperatures will begin to trend upward beginning
next weekend. Ridging aloft will transition east from the
intermountain west, becoming oriented across the central plains
early next week. After highs in the lower 80s for Friday,
temperatures will trend toward the 90s by the end of the weekend.
In addition, precipitation chances will begin to fall as well as
ridging builds across the central Conus.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 637 PM CDT Mon Jul 25 2016

VFR conditions are anticipated to prevail through the TAF Period
for all of western and north central NE. Main concerns are
thunderstorm potential tonight and tomorrow afternoon/evening.
Of note, there are thunderstorms ongoing in west central SD and
northeast CO.

There are concerns for isolated thunderstorms before midnight
north and along a line from Oshkosh to Whitman to Valentine.
However, confidence remains low in TS impacting our area;
therefore, no mention of TS in the KVTN TAF at this time.

The last operational HRRR run tracks a MCS into the northwest
portion of the forecast area and beyond overnight, however, the
experimental HRRR and most flavors of WRF limit any convective
development in the forecast area. The latter matches our current
thinking. The former solution appears to be too optimistic. We
will continue to monitor the aforementioned thunderstorms but
think, if the west central SD thunderstorms were to persist and
linger, they would just impact the extreme northwest portion of
the forecast area.

Tomorrow, attention turns to thunderstorms chances. Increased
chances along and north of a line from Antioch to Halsey to
Oneill. Best chances will be near the SD border and near the end
of the TAF period (approaching 00Z Tuesday). Still uncertainty in
timing and extent of TS coverage. Enough confidence though based
on model guidance to place Prob30 in KVTN TAF.


.LBF Watches/Warnings/Advisories...


SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...ET is the U.S. government's official web portal to all federal, state and local government web resources and services.