Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 192000

Area Forecast Discussion
National Weather Service North Platte NE
300 PM CDT Mon Mar 19 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 239 PM CDT Mon Mar 19 2018

The latest deterministic short term guidance indicates northwest
flow developing behind the passing closed upper low. This is in
response to a developing ridge over the western conus. Thus skies
will clear from west to east with increasing subsidence overnight.
The guidance does hint at least a slight mention of light snow
going through the overnight for our far eastern zones. Current
feeling is that the guidance is a bit slow on the exit, given the
current trends, but will keep some pops for our far east through
sunrise. Additional QPF overnight is expected to be light, with no
more than a tenth of an inch liquid expected. This would suggest
most areas across our far east would see less than an inch
additional snow.

A minor concern will be the possibility of low stratus/patchy fog
where skies clear overnight as the boundary layer is moist from
the recent precipitation. Though, northwest or westerly sfc flow
is not typically favorable for development. Still, NAM buffer
soundings hint at the potential, so we will monitor.

Subsidence and a light westerly/northwest downsloping wind on
Tuesday will help warm temperatures back into the upper 40s to
lower 50s. We will be starting the day off cool as guidance shows
teens and lower 20s for lows tonight. Those overnight lows are
going to be highly dependent on how fast the clearing occurs
behind the departing low. At this point we`re focusing the coolest
temperatures for locations west of highway 83, but expect
sufficient clouds to keep lows well into the mid to upper 20s to
the east. Otherwise some of the latest guidance hints at a weak
disturbance sparking off a light shower or flurry tomorrow
afternoon for the Sandhills. We expect some convective enhancement
in the northwest flow with even some low topped cumulus possible.
Though at this point the lower levels seem too dry for any
precipitation to hit the surface. So for now, we expect mainly
"virga-showers," but will continue to monitor.

.LONG TERM...(Tuesday night through Monday)
Issued at 239 PM CDT Mon Mar 19 2018

Sensible weather concerns are low through Thursday with a warming
and drying trend taking hold. Thereafter the pattern becomes more
so unsettled Friday and beyond with multiple chances for
precipitation present. While there are some possible fire weather
concerns Friday, and maybe Saturday, confidence is below-average
given the uncertainty in that time frame.

The large scale pattern will feature modest height falls across
the Central and Northern Plains as the ridge in the western CONUS
builds Tuesday night-Wednesday. The upper-level ridge will extend
roughly from the Four Corners to Alberta and Saskatchewan by
Wednesday with northwest flowing prevailing overhead. The upper-
level ridge will then shift east become positioned across the
High Plains and across the Canadian Prairies by Thursday. This
setup will be conducive for modest downsloping flow and will help
promote the aforementioned warming and drying trend. Highs are
expected to be above-normal both days given the combination of
mixing and insolation with appreciable low-level warm air
advection also occurring. While highs will be a few to several
degrees warmer than normal Wednesday, current thinking is highs
will be about 10-15 or more above there seasonable normal values
by Thursday. Highs Thursday are forecast largely in the 60s to
near 70 in extreme southwest NEB.

Beyond Thursday night, there are apparent differences in phase and
amplitude with the large scale pattern. Overall guidance is in
fair agreement with regard to the ridge breaking down late this
week. A weak shortwave trough is forecast to track east across
the Central Plains late Friday-Friday night with notable timing
differences noted. Thereafter another stronger disturbance will
affect the region Saturday night-Sunday associated with the upper-
level trough in the western CONUS. Of which, the primary
disturbance will move east into the Northern and Central High
Plains Saturday night/early Sunday. A forecast challenge will be
how warm Saturday can get. Otherwise Friday looks to be the
warmest day out of the two days with similar highs forecast Friday
compared to Thursday at this time. The first disturbance will
prompt chances late Friday-Friday night, however, all rain is
forecast given the warm atmospheric environment. Otherwise, the
latter disturbance will prompt another period of increased chances
Saturday night-Sunday with a better chance of a snow or a mix
associated with it. However, the threat for any hazardous weather
in either time period is low. A cool down is then expected to be
in place Sunday with highs expected to be near to slightly below
seasonable temperatures.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1226 PM CDT Mon Mar 19 2018

The latest guidance indicates that the banded precipitation that
is currently impacting west central Nebraska will continue to
weaken as the next band forms the east central part of the state.
Timing on the break up of the banded snow is uncertain, thus will
employ a consensus approach and expect updates in the near term.
That being said, expect improving flight conditions this afternoon
for TAF sites along and west of a KLBF to KVTN line. East of this
line, expect conditions to deteriorate in the near term, but
improve later this evening. Again, forecast confidence in the
large scale is good, but timing and locational details are
uncertain. Otherwise peak gusts will remain at 20kts or less
through the forecast period.




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