Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 181115 AAA
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
515 AM CST Thu Jan 18 2018

.SHORT TERM...(Today and tonight)
Issued at 356 AM CST Thu Jan 18 2018

The RTMA temperature analysis indicates mild air has spread across
the nrn Plains, ern WY and wrn Neb. The temperature forecast today
uses a blend of bias corrected guidance for highs in the 50s to
around 60. The bias corrected blend was cooler than the straight
guidance blend by several degrees across the partial to nearly
completely snow covered areas.

Warmest temperatures are expected across far Swrn Neb where no snow
is on the ground. H850 temperatures continue their march upward to
around 10C by late this afternoon. The models show scattered high
clouds across the nrn plains moving into Neb today. The high clouds,
snow cover and/or frozen ground are the basis for undercutting
guidance.

The temperature forecast tonight uses a blend of bias corrected
guidance for lows in the teens to upper 20s. This was a couple of
degrees warmer than the straight guidance blend. H850mb temperatures
continue to rise to around 15C by Friday morning.

.LONG TERM...(Friday through Wednesday)
Issued at 356 AM CST Thu Jan 18 2018

A lee surface trough will deepen over eastern Colorado on Friday and
allow for a fetch of downsloping southwest flow across the CWA. This
combined with strong warm air advection will allow for a pleasantly
warm and dry day for the entire forecast area.  The latest guidance
has trended temperatures upward, now suggesting widespread 50s and
even some 60s for afternoon highs.  Temperatures take a downward
trend on Saturday as a weak front backs west across the forecast
area.  Easterly flow with origins from the northern prairies and
increasing clouds will keep highs mainly in the 40s.

The long range models continue to prog a potentially significant
winter system that would bring accumulating snowfall to much of the
forecast area late Saturday through Sunday.  As has been the recent
trend, the arrival of the system has continued to slow and the GFS
remains on the faster end of the envelope.  The basic idea is that
ample QG ascent/fgen banding will produce widespread snowfall with
the main/heaviest band/s/ targeting the central Sandhills and east.
Am a little concerned that the models show a zone of EPV reduction
which would suggest some drying in the mid levels.  We could see a
period of -fzdz or convective influences in the banded snowfall.
Will continue to follow the overall blended model guidance for this
run as the system is still way out over the Pacific, but begin to
ramp up notifications on the potential impacts from this storm,
especially since wind gusts will increase to 25 mph or greater
during the precipitation.  Bottom line, keep an eye on the forecast
going forward.

Cyclonic flow on the backside of the departing system will allow
temperatures to trend closer to average for Sunday and early next
week.  Aloft we see a westerly trajectory, which could provide for
additional chances of light qpf next week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 515 AM CST Thu Jan 18 2018

Sfc low pressure circulating through Srn Canada will continue to
pull dry stable air into wrn and ncntl Nebraska. VFR is expected
all areas today and tonight. High cloudiness from a storm system
affecting the Wrn U.S. will move in today last into tonight.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...CDC
LONG TERM...Jacobs
AVIATION...CDC


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