Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 251926

Area Forecast Discussion
National Weather Service North Platte NE
226 PM CDT WED MAY 25 2016

.SHORT TERM...(This evening through Thursday)
Issued at 226 PM CDT Wed May 25 2016

Tonight and Thursday...a fast moving batch of high based showers and
thunderstorms move across the fcst area this aftn and exit around
06z this evening. The main risk is gusty winds with the NAM and HRRR
showing 40 to 50kt sfc wind gusts. Ground truth winds would probably
be 40 to 50 mph. This disturbance will send a weak cold front
through the fcst area into Nrn KS which will be the focus for severe
weather late Thursday aftn...23z or so.

The area of concern for severe weather Thursday is mainly along and
south of Interstate 80 where 800mb computed cape rises to over 3000
j/kg. The forecast area is in easterlies north of a stationary front
with dew points in the upper 50s per NAM. Nonetheless bufkit shows
an environment favoring dominant right moving supercells with high
cape at McCook. The situation at North Platte is much stabler with
less cape favoring shallower storms.

SPC has outlooked Swrn Neb for severe weather and if the moisture
shows up and storms are able become rooted in the lower levels vs
remain elevated...then severe weather should develop.

.LONG TERM...(Thursday night through Wednesday)
Issued at 226 PM CDT Wed May 25 2016

Thursday night...Severe thunderstorms possible, especially during
the evening. A warm front will beceom positioned near the
Nebraska/Kansa border early Thursday evening. Severe parameters
suggest the potential for some very large hail greater than 2
inches diameter, damaging winds, and a few tornadoes. The area of
greatest concern will be south of an Ogallala through Broken Bow
line. 0-3km mucapes of 2000-4000 j/kg with a 0-2km vgp gradient
present. Granted, some changes with position of front, surface
dewpoints, and low/mid level shear will occur, which will alter
postion of the greatest severe potential.

Friday/Friday night into Saturday...a closed upper low will track
from eastern Colorado, across Nebraska into the eastern Dakotas.
While the sever potential will be less, of greater concern will be
locally heavy rainfall with amounts up to 2 inches possible. Much
of this rainfall will fall in the North Platte Basin, South Platte
Basin, and Elkhorn Basin. Other increased chances for
thunderstorms arrive Memorial Day into Tuesday as a northern stream
trough drops into the Northern and Central Plains.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1222 PM CDT Wed May 25 2016

The showers...or perhaps developing isolated tstms...across Ern
Wy and Wrn Neb should move rapidly east this afternoon and this
evening. The NAM and HRRR models suggest wind gust potential from
dry downbursts reaching 40 to 50kt in the model which might mean
30 to 40kt ground truth. This activity should move east at around
40 mph and exit the fcst area around 06z or sooner. VFR is
expected all areas thereafter through 18z Thursday.


Issued at 226 PM CDT Wed May 25 2016

North Platte additional water release of 1000 cfs
from lake McConaughy is underway which will pass 3500 cfs through
North Platte and raise the river to near 6.9 ft over the
weekend...just below major flood stage...7.0 ft. This in turn will
cause the Platte river at Brady to reach flood stage early next week.

High river flows will continue on the South Platte river. The models
suggest heavy thunderstorms may form over Northeast Colo Friday
which could eventually cause higher flows on the South Platte and
Platte rivers.


.LBF Watches/Warnings/Advisories...


LONG TERM...Roberg
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