Special Weather Statement, NWS North Platte, NE

Area Forecast Discussion
National Weather Service North Platte NE
347 PM CDT Mon Oct 2 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 347 PM CDT Mon Oct 2 2017

Potent upper level trough centered across the central Rockies
will once again influence the weather across the central plains
tonight. Favorable dynamics aloft will coincide with a southerly
low level jet, and bring the potential for thunderstorms to the
region tonight. The focus will be an H850mb front that extends
from northwest KS to northeast Nebraska. As the southerly low
level jet increases, isentropic upglide will rapidly increase to
the north of the front with widespread shower and thunderstorm
development expected. For central and parts of southwest Nebraska,
some large hail is possible with the stronger storms, as this
area will see nearly 2000 J/KG of mid level cape supportive of
more vigorous updrafts and the potential for large hail. This area
also stands the potential for training of storms for a time later
this evening, which could lead to possible flash flooding. A
flash flood watch has been issued for this possibility. After
midnight the low level jet begins to veer southwest with the
heavier rain potential shifting east and most of the precipitation
ending by 2:00 or 3:00 AM CDT.

A cold front will cross the area late tonight, which will shunt much
of the low level moisture east of the area. Drier air aloft will
also move into the area in the mid and upper levels, so expect
mostly sunny skies across much of the area by the afternoon hours
Tuesday.

.LONG TERM...(Tuesday night through Monday)
Issued at 347 PM CDT Mon Oct 2 2017

Rain chances increase Wednesday night through Friday. This 48+ hour
rain chance is a result of the blend of models with different timing
and intensities for the last of the upper level energy exiting the
Wrn U.S..

The GFS is more amplified and slower while the ECM is faster and
less prolific with rainfall. This is probably the result of return
moisture and availability in the models. The stronger GFS is
preferred given the very high amplitude anomaly in the current conus
500 mb height circulation. This circulation is expected to weaken
somewhat but continue through Thursday.

The models are in good agreement sending a strong cold front through
the region Sunday. There is a slight chance of showers with the
front across Wrn Neb. Otherwise, Saturday will be the warmest day of
the next 7 with highs in the 70s, perhaps warmer. H850mb
temperatures rise to around 20C. The cool down Sunday and Monday
sends h700mb temperatures to around -10C. This would support highs
in the 50s next Monday, if not cooler.

Model blended data plus bias correction was the basis for the
temperature forecast. The expected cloud cover and rain Thursday and
Friday is offset by warm air advection for highs in the 60s.
Wednesday will be the coolest day with highs in the 50s. The
increase in clouds Wednesday night precludes any freeze Thursday
morning. Wednesday morning will be the coolest with lows in the
lower 30s across Nrn Sheridan County.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 106 PM CDT Mon Oct 2 2017

Lower ceilings and another round of showers and thunderstorms are
likely tonight. Most areas will see deteriorating conditions
with widespread MVFR expected. These conditions should persist
until around sunrise Tuesday morning, when ceilings should begin
to lift behind a cold front.

&&

.HYDROLOGY...
Issued at 347 PM CDT Mon Oct 2 2017

A flash flood watch was issued for portions of southwest-central NEB
early this morning. 24 hr observed reports and the 24 hr MRMS
rainfall analysis since yesterday showed multiple swaths of heavy
rainfall exceeding 1.75” across parts of Hayes and Frontier counties
to Custer county to Holt and Boyd counties. In addition, rainfall
exceeded at least 3 inches across parts of Custer county with a
received local storm report of 3.4” in Merna. Current pattern
suggests potential for 1-3 inches. Latest 1-hr and 3-hr FFG show
values largely under 1.5" and 2", respectively. Notably, 3-hr FFG in
parts of Custer county are under 1.5" based on current soil moisture
conditions. Given the environment and these antecedent conditions
combined with the high likelihood of training storms suggest
favorable conditions for localized flash flooding this evening in
the flash flood watch area.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through late tonight for NEZ037-038-059-070-
071.

&&

SHORT TERM...Taylor
LONG TERM...CDC
AVIATION...Taylor
HYDROLOGY...ET

Hazardous Weather Outlook
National Weather Service North Platte NE
412 PM CDT Mon Oct 2 2017

NEZ004>010-022>029-035>038-056>059-069>071-094-032115-
Sheridan-Eastern Cherry-Keya Paha-Boyd-Brown-Rock-Holt-Garden-
Grant-Hooker-Thomas-Blaine-Loup-Garfield-Wheeler-Arthur-McPherson-
Logan-Custer-Deuel-Keith-Perkins-Lincoln-Chase-Hayes-Frontier-
Western Cherry-
412 PM CDT Mon Oct 2 2017 /312 PM MDT Mon Oct 2 2017/

This Hazardous Weather Outlook is for portions of western and
north central Nebraska.

.DAY ONE...TONIGHT.

Thunderstorms will develop during the evening hours. Some storms
may produce hail, primarily for areas along and east of a line
from Imperial, to North Platte, to Arnold. Locally heavy rain
could lead to flash flooding across portions of central and
southwest Nebraska.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

Temperatures will drop into the lower to mid 30s Wednesday
morning across parts of Sheridan and western Cherry counties.
Frost, or even a light freeze, is possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation should not be needed through tonight.

&&

Get your weather, hydrological, and climate information at
http://www.weather.gov/northplatte

Taylor

Special Weather Statement
National Weather Service North Platte NE
742 PM CDT MON OCT 2 2017

NEZ059-071-030130-
Frontier NE-Lincoln NE-
742 PM CDT MON OCT 2 2017

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL FRONTIER...SOUTHEASTERN
LINCOLN AND EASTERN HAYES COUNTIES UNTIL 830 PM CDT...

At 742 PM CDT, Doppler radar was tracking a strong thunderstorm 9
miles southwest of Curtis, moving northeast at 50 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Curtis, Eustis, Moorefield, Stockville, Maywood, Quick, Hansen
Memorial Reserve State Wildlife Management Area and Dancing Leaf
Earth Lodge.

This includes Highway 83 between mile markers 30 and 47.

LAT...LON 4052 10079 4053 10078 4090 10034 4081 10022
      4070 10022 4070 10006 4067 10002 4037 10062
TIME...MOT...LOC 0042Z 229DEG 44KT 4052 10060

Snively