Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 210847

Area Forecast Discussion
National Weather Service North Platte NE
347 AM CDT Sun May 21 2017

Issued at 347 AM CDT Sun May 21 2017

H5 closed low that has affected western Nebraska the last several
days is moving to the north northeast into Minnesota early this
morning. Wave coming around this h5 low on the backside dropping
through the Great Basin and crossing wyoming as seen in WV imagery.
H5 ridge along both coasts with a surface cold front along the


.SHORT TERM...(Today and tonight)
Issued at 347 AM CDT Sun May 21 2017

HRR and Rap in good agreement early this morning. Will continue
frost headlines with temperatures hovering around the freezing
mark. Some valley fog early this morning with basically North
Platte only reporting site going down. TD spreads almost non
existent and have included patchy fog over southwest where I
encountered ground fog late this evening driving back from
Colorado along I80 and south into the Kansas border but will have
to monitor for updates. Strong northwest flow to continue today as
inversion breaks. Somewhat of a downslope flow component and with
full sun and good insolation temperatures to rise into the mid to
upper 60s. With the heating of the day and cooler air aloft lapse
rates steepen and some marginal cape could see some TRW in the
northwest and the southwest where the leading edge of the wave are
evident in satellite early this morning. Some precipitation to
linger across the north into early evening and over southwest
Nebraska over night as the wave moves through. Warmer temperatures
tonight with lows on Monday morning in the upper 30s northwest
and the low 40s over the remainder of the forecast area.

.LONG TERM...(Monday through Saturday)
Issued at 347 AM CDT Sun May 21 2017

Beginning 12z Monday.  Overall there`s good agreement in the medium
range with a shortwave that will increase precipitation chances
Monday across the entire CWA.  The models continue to prog some
instability, at least sufficient enough for a thunder mention.  It
seems the brunt of the energy is trending west with the system, so
will continue POPS at 50% or less for now, with any precipitation
activity removed from the CWA by late Tuesday.  Thereafter, an
approaching potent trough off BC/PAC NW will effectively breakdown a
amplified western CONUS ridge to the east and allow for a drying
trend for the CWA, through at least Thursday morning.  After below
average temperatures early week, increasing subsidence with the
building ridge will allow temperatures to warm to near seasonal or
slightly above average for this time of year.  Thursday appears to
be the warmest day of the work week as highs rise into the 70s and
possibly lower 80s.  However the aforementioned PAC NW trough will
continue to advance east and spin up a deep low north of the
Canadian border.  The trough will force a weak front through the cwa
Thursday as southwest flow aloft develops over the central plains.
As a result, precipitation chances ramp up once again to round out
the work week, with thunderstorms possible. The CWA remains in sw to
near zonal flow through next weekend with the prospect of several
disturbances sparking off convective rains.  Timing on these
features is difficult this far out, but with decent model agreement,
will make no changes to the long range blend.

Otherwise Wednesday morning still appears to have the potential for
a late season frost over much of the Sandhills.  Guidance continues
to prog mid 30 lows from northwest Nebraska through the heart of the


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1120 PM CDT Sat May 20 2017

Local IFR/LIFR may be forming in the river valleys east and south
of a line from KLBF-KTIF-KBUR. The NAM suggests this in the
visibility product and it appears to be underway at KLBF.

VFR is generally expected all areas 14z Sunday through 06z Sunday

Local MVFR could develop in isolated showers and thunderstorms
18z-02z Sunday. At 04z...the disturbance on satellite between
KGGW-KHVR-KGTF dives south Sunday. The HRRR model suggests this
disturbance could produce the showers as early as 18z Sunday. Most
other models miss this event.


Issued at 347 AM CDT Sun May 21 2017

Flood warning continues at Lewellen and the South Platte is coming
up to due to snowmelt and abundant moisture coming down along the
front range. South Platte river was up last evening when I crossed
it in Commerce City. RVS on the South Platte River at North Platte
and others may be needed with recent moisture. Elkhorn River near
Atkinson coming up.


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



LONG TERM...Jacobs
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