Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 140529

Area Forecast Discussion
National Weather Service North Platte NE
1229 AM CDT Wed Mar 14 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 332 PM CDT Tue Mar 13 2018

The primary forecast challenge through Wednesday is temperature as
an upper ridge spreads onto the Plains and a surface high pressure
places Nebraska in return flow.

This evening and tonight... Continued clear skies with plenty of dry
air in place. Even the closest cirrus decks upstream are in
northeast SoDak or western CO per WV/IR/Vis imagery. A thermal ridge
pushes onto the northern Plains overnight with decent downslope flow
(25-30kts at H85). Thinking enough winds at the sfc and WAA aloft to
prevent total decoupling. Kept lows slightly above the MAV/MET/ECS
blend in the mid/upper 20s. Temps may drop lower in the river

Wednesday... Trended max temps up toward the warmer MAV/MET guidance
to account for abundant sunshine, southerly low level flow right up
the High Plains, and H85 temps exceeding 10C. A limiting factor may
be relatively shallow mixing, as forecast soundings suggest H8-85.
Humidity drops below 20 percent in the panhandle and western
Sandhills in the afternoon, but overall light winds alleviate any
major fire weather issue.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 332 PM CDT Tue Mar 13 2018

All eyes are on the storm system affecting western and north central
Nebraska Thursday night and Friday. The models show very strong
moisture advection developing ahead of a closed h700mb low forecast
to track along the NEB-KS border. The morning GFS run is much
stronger with this system. The moisture advection could be too
strong as the NAM shows thunderstorms forming over ern KS Thursday
night. This would block a portion of the very strong moisture
transport shown by the models.

Nonetheless, the forcing is very strong with deep lift and folded
theta-e in the -12C to -18C snow growth layer. This should produce
convectively enhanced bands of heavy rain, freezing rain, sleet and
snow which lift north through Nebraska late Thursday night and
Friday morning. 1+ inch per hour snowfall rates are possible.

The forecast uses a blended model approach which produces 0.25 to 1
inch of liquid across the forecast area. Some of this will be rain
and the GFS and NAM show a warm nose around 800mb which would
support the freezing rain and sleet early Friday morning. The best
guess on max snow totals is around 6 inches across northern Neb. But
this could be conservative given the forcing.

Most of this snow is expected to fall Friday morning. The banded
snow should diminish Friday afternoon as the upper level low moves
east. Later forecasts may have to increase the snowfall forecast but
the event is still three days away and much can change in terms of
the location of the heavy snow. WPC suggested a band of 6-12 inch
snowfall will develop with a confidence level roughly 45 percent.

Another winter-type storm system will be moving through the Plains
Sunday and Monday but the models show this storm tracking through
either KS, Neb or SD so the potential forecast errors are very
large. Chance POPs are in place during this time.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1229 AM CDT Wed Mar 14 2018

Visual flight rules expected through the next 24 hours with mostly
clear skies and light and variable winds under 10kts.




SHORT TERM...Snively
AVIATION...Power is the U.S. government's official web portal to all federal, state and local government web resources and services.