Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 240834

Area Forecast Discussion
National Weather Service North Platte NE
334 AM CDT Wed May 24 2017

Issued at 245 AM CDT Wed May 24 2017

At 08z...weak surface high pressure extended across western Nebraska.
An upper level low was centered in southern Iowa, with another upper
low upstream in southern British Columbia. A few high clouds were
streaming south across western Nebraska. Temperatures ranging from
34 at Gordon and North Platte airports, to 47 at Broken Bow.


.SHORT TERM...(Today and tonight)
Issued at 245 AM CDT Wed May 24 2017

Today/Tonight...An upper level low in southern British Columbia will
track east into southwestern Saskatchewan by early this evening.
This will drive a cold front through eastern Montana this afternoon.
Ahead of this, a transitory ridge will move east across the Northern
and Central Plains today. Southerly winds will develop across
western Nebraska. Winds will remain light across the southeastern
zones at 5 to 10 mph, while increasing to 15 to 25 mph across the
northwestern zones. Highs today were nudged up a few degrees from
the mid 70s eastern panhandle and adjacent western Sandhills to the
upper 60s to near 70 central and eastern areas. Skies will remain
mostly sunny today, which has be absent for the past several day.
For tonight, the upper low will slow and remain across southern
Saskatchewan, with the cold front pushing into the northwest
Sandhills late tonight. Southerly winds ahead of the front with
increasing mid cloudiness will allow for a milder night with lows
mainly in the upper 40s. As the upper trough digs south across
Wyoming and the western Dakotas, A few showers or thunderstorms are
possible northwest of the forecast area. While forecast models hint
at the potential for isolated showers in western Nebraska, the
airmass is fairly dry below 700 mb tonight. Therefore virga may
occur, with no precipitation expected to reach the ground.

.LONG TERM...(Thursday through Tuesday)
Issued at 245 AM CDT Wed May 24 2017

A Couple of disturbances will rotate southeast on the periphery
of southern Canada upper low Thursday and Friday. The first of
these will arrive Thursday evening with showers possible across
southwest Nebraska Thursday evening. The second and stronger
disturbance will arrive later Friday afternoon and evening. This
will bring the potential for strong, perhaps even a few severe
thunderstorms across southwest Nebraska. Some embedded thunder
within area of showers is possible elsewhere but not expected to
be severe. Focusing on the severe potential across southwest
Nebraska, daytime heating will combine with increasingly moist
southeast low level upslope flow. Steep mid level lapse rates will
help contribute to surface based cape values approaching 1500 J/KG.
Scattered thunderstorms should initiate in the favorable upslope
environment across the panhandle by late afternoon. These will
track east-southeast across much of the area through the evening
and overnight, likely forming upscale into an MCS. Prior to MCS
development, isolated supercells with the potential for large
hail will exist within area of higher instability across
southwest Nebraska.

This disturbance will be slow to exit Saturday, and have increased
chances for rain especially during the morning hours. Otherwise
should see mostly cloudy skies and continued rather cool, with
highs reaching the upper 60s by late afternoon when some breaks in
the cloud cover should develop.

In the wake of this system, subsidence aloft will allow for more
sunshine Sunday. Northwest winds will increase some, with gusts of
25 to 30 mph possible. The northwest low level flow will advect
some slightly warmer air in from the west, with highs most areas
nearing 70 degrees.

Upper low will remain in southern Canada, moving ever slow slowly
toward the great lakes region Memorial Day. Models continue to
advertise more energy diving south-southeast across the area, with
a few afternoon showers possible across northern Nebraska.
Again highs to remain below normal, with upper 60s for most
locations both Memorial Day and Tuesday.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1130 PM CDT Tue May 23 2017

VFR is expected all areas overnight through Wednesday evening.

Timing tools suggest the bank of VFR cigs across Ncntl Cntl will
move south of this area by 10z-12z Wednesday morning. High clouds
across Wrn Neb will build east during the day Wednesday as sfc low
pressure across Alberta moves east and a secondary sfc low forms
over ErnWY/Wrn SD.


Issued at 245 AM CDT Wed May 24 2017

The South Platte river will continue to rise from near Roscoe
through North Platte, attributable to recent heavy precip and snow
melt across eastern CO. At Roscoe, the river is forecast to rise
above Action Stage (three-quarters bankfull) and reach a crest of
7.3 feet forecast this evening, followed by a steady or slight fall
into this weekend. Downstream, sharp rises in the stage are being
observed at Paxton and North Platte. At North Platte, the crest is
forecast to reach just below Action Stage Thursday night into
Friday, then fall off slightly this weekend.


Frost Advisory until 8 AM CDT /7 AM MDT/ this morning for NEZ004-



LONG TERM...Taylor
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