Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 220515
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1115 PM CST Tue Feb 21 2017

.SYNOPSIS...
Issued at 300 PM CST Tue Feb 21 2017

Ridge over the east coast and large cutoff low over Arklatex.
Zonal flow over the northern CONUS.

&&

.UPDATE...
Issued at 700 PM CST Tue Feb 21 2017

All Red Flag Warnings across western and north central NEB have
expired. Winds have lessen with light winds, under 10 mph,
largely present across the local forecast area. While low
humidity remains in portions of western NEB, near 15-20 percent,
humidity will recover quickly -- above 50 percent by late
evening.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 300 PM CST Tue Feb 21 2017

Have issued a short fuse Red Flag Warning for all areas except for
the far northern portions of the state, as criteria has been reached
and is expected to persist for 3 hours. The other story is the
record warmth, with North Platte now 1 degree away from the all time
record high of 79 degrees.

For tonight, with the dry air and clear skies, temperatures will
once again drop quickly. Favored cold drainage areas like river
valleys etc., will likely fall to near or just below freezing.
Elsewhere lows will generally will range in the mid 30s to lower
40s.

Wednesday, mid level frontogenesis (FGEN) will begin to strengthen
with the approach of the storm system. No precipitation will occur
during the day Wednesday, but an increase in mid level cloudiness
will occur due to the FGEN by late afternoon. Not as warm Wednesday
behind a weak cold front, but still much warmer than average for
this time of year. This will lead to yet more fire weather concerns,
as relative humidity drops to near 20 percent and gusty northwest
winds will approach 25 mph. The 25 mph gusts will generally be along
and east of a Valentine to North Platte line, where fire weather
headlines are possible.

.MID TERM...(Wednesday night through Friday)
Issued at 300 PM CST Tue Feb 21 2017

Wednesday night through Friday, aka. the storm. After
unseasonably warm temperatures Today and Wednesday, cold
temperatures and the threat for an approaching winter storm is the
main forecast concern in the mid range. Beginning Wednesday
night, a strong H5 trough will approach the high plains of Eastern
Wyoming and the Nebraska panhandle from the northern Rockies. Mid
level frontogenesis will increase sharply overnight from the
Nebraska panhandle eastward into northern Nebraska. Efficient
precipitation production will commence toward Thursday morning
across the sandhills. Cross sections from the NAM12 and GFS this
morning indicate broad sloped lift through the dendritic zone
which quickly becomes saturated by Thursday morning. This area of
lift is centered from the east central panhandle through the
sandhills into northeastern portions of the forecast area. In
addition, a nice area of negative EPV was noted as well in the
cross sections which may lead to local enhancement of snowfall.
Strong isentropic lift was noted as well in the 295 and 300K
surfaces in both the NAM12 and GFS solutions. Both the NAM12 and
GFS solutions had trended slightly farther north with their best
lift this morning and are now in decent agreement with the 12z
ECMWF solution. That being said, felt confident enough to issue a
winter storm watch for Wednesday night through Thursday night
across the sandhills into north central Nebraska. In these areas
based on a blended QPF forecast, and snow ratios of 10:1
transitioning to 13:1, came up with storm totals of 6 to 10 inches
roughly north of highway 92. Winds will not be overly strong
initially, however, as the surface low deepens across northeastern
Kansas into Iowa Thursday night, there will be the potential for
some blowing snow, particularly in the eastern forecast area
Thursday night into Friday morning.

.LONG TERM...(Friday night through Tuesday)
Issued at 300 PM CST Tue Feb 21 2017

Snow will continue to taper off Friday night with little
additional accumulation expected. Upper closed over northern Iowa.
Lows Friday night falling into the single digits and teens with
skies to the northwest clearing late. Upper ridge will push east
over night with warming temperatures aloft. Highs Saturday from
upper 20s northwest to the upper 30s south. Fairly zonal pattern
with west to southwest down slope flow. Temperatures in the teens
Saturday night with warmer air aloft. Temperatures in the 30s and
40s on Sunday. Slight chances of snow Sunday night south with
system moving across Kansas. Warming Monday ahead of upper trough
moving off the west coast. Highs Monday in the 40s and 50s and in
the 30s north to 50s south on Tuesday as a warm front lifts north
across western Nebraska Late Monday into Tuesday. Chances of rain
continued through the day Tuesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1115 PM CST Tue Feb 21 2017

The main concerns the next 24 hours are winds. Otherwise, VFR
conditions are expected to prevail through the TAF period. Latest
satellite imagery shows FEW-SCT high clouds across southwest NEB
to central NEB, elsewhere skies are clear. Winds have diminished
and range from light and variable to southwest up to 10 mph.

Breezy conditions will develop late morning/early afternoon
tomorrow. While gusts tomorrow will not be as strong compared to
today, gusts approaching 25 mph are expected across north
central NEB and the eastern NEB Panhandle with gusts up to 20 mph
expected elsewhere. Winds will then diminish in the late
afternoon/early evening.

&&

.FIRE WEATHER...
Issued at 300 PM CST Tue Feb 21 2017

Minimum relative humidity will fall into the 20 percent range over
most of western and north central Nebraska on Wednesday. Breezy
west winds will gust through the afternoon. Fire zone 209 may
need highlights.

&&

.HYDROLOGY...
Issued at 300 PM CST Tue Feb 21 2017

New releases will be flowing into the North Platte River from
McConaughy.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from late Wednesday night through Friday
afternoon for NEZ004-094.

Winter Storm Watch from Thursday morning through Friday
afternoon for NEZ005>010-022>029-035>037.

&&

$$

UPDATE...ET
SYNOPSIS...Power
SHORT TERM...Taylor
LONG TERM...Power
AVIATION...ET
FIRE WEATHER...ET/Power
HYDROLOGY...Power



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