Special Weather Statement, NWS North Platte, NE

Area Forecast Discussion
National Weather Service North Platte NE
339 AM CDT SAT JUL 30 2016

.SHORT TERM...(Today and tonight)
Issued at 339 AM CDT Sat Jul 30 2016

Today and Tonight...the weather situation today and tonight is
similar to Friday with three rounds of convection. The ongoing
convection across Ncntl will dissipate this morning as the low level
jet weakens and lapse rates become less steep. This area of rain
formed as a result of the low level jet...an upper air disturbance
across SD and steepening lapse rates.

Satellite suggests a second area of steep lapse rates across Ern Wy
and the Neb panhandle. It is believed this area will drift east
today and become the focus for severe weather this afternoon. The
Black Hills would be the source area of storm development. The HRRR
and NAM suggest the White River Valley in SD as a source region. The
models show a plume of deep moisture moving up the Cntl High Plains
late this afternoon the forecast shades the better rain chances...30
percent along highway 61 and across the Ern Panhandle.

A modest 30kt low level jet will form tonight and the model
consensus suggests another round of thunderstorms will form across
Ncntl Neb as a result of lingering evening convection...the steep
lapse rates and forcing from the low level jet.

The temperature forecast uses a four-way blend of guidance plus bias
correction for highs in the 80s and lows in the 60s. Sfc dew points
will rise into the mid to upper 60s for humid conditions.

.LONG TERM...(Sunday through Friday)
Issued at 339 AM CDT Sat Jul 30 2016

Mid range-Sunday through Monday night: Right out of the gate, there
are some significant model differences between the 00z NAM12 and GFS
solutions tonight. First off, the NAM12 develops a MCS tomorrow
evening, pushing this feature to the southeast across the forecast
area Saturday night. The result is a frontal boundary which becomes
anchored along the KS/Nebr border Sunday into Monday. The GFS is
similar but weaker with the MCS and frontal boundary, lifting
washing this feature out Sunday night, allowing very warm air to
push into the forecast area for Monday. This shows up in the latest
statistical forecast guidance which has a 10 degree spread for highs
Monday with the GFS MAV guidance much warmer than the NAM MET
guidance. For highs on Monday, decided to weigh the forecast heavily
on the inherited forecast, weighted more toward the warmer MAV
guidance. That being said, decided to limit precipitation chances
for Sunday night confining them to the southwestern forecast area as
both the NAM and GFS solutions do have a surface boundary anchored
across southern Nebraska. Will confine the chances to the evening
hours as the GFS lifts the front north overnight. Shifting into
Monday, as mentioned above, there are some significant model
differences with respect to temperatures on Monday as well as the
threat for thunderstorms late Monday into Monday night. With the NAM
having a front anchored to the south of the forecast area, it
remains the coolest solution for highs Monday. It also generates
precipitation Monday night as a low level jet crosses perpendicular
to the frontal boundary. The GFS solution is drier and confines
precipitation chances to Monday night INVOF of an approaching
surface trough/weak frontal boundary. Will hold onto pops for Monday
night as there is some mid level warm air advection which over
spreads the front Monday Night. This warm air advection is
strongest in the east and that is where pops were retained.

Long range-Tuesday through Friday: A trough of low pressure aloft
will push onshore Tuesday which will amplify ridging downstream
across the central and northern plains. Much warmer air will flow
into the forecast area on Tuesday which will result in highs
reaching the mid to upper 90s. The ECMWF solution does hold onto
some cooler air and additional low level moisture for Tuesday, so
decided limit highs to the middle 90s. The next threat for pcpn in
the extended will arise on Wednesday night as a cold front passes
through the forecast area. Temperatures behind the front will be
in the 80s for Thursday and Friday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1151 PM CDT Fri Jul 29 2016

Initial forecast problem lies with potential for development of
low stratus and fog. Latest runs of RAP/HRRR have backed off some
on potential for low clouds and there is no resprictions to vsby
indicated in LAMP guidance. However serly winds in moist
environment tends to develop cloud cover near or just after
sunrise so have backed off some in light of newer guidance but
confidence is low either way.

The second issue is development of TSRA overnight in association
with mid level disturbance and LLJ. Low level winds have not yet
developed as expected but short range models are similar in
developing a line also twd sunrise, but east of KLBF and KVTN.
Have therefore not included mention in morning hours. NAM keys in
on large scale convection twd the end of this TAF period and have
included mention at KVTN.

&&

.LBF Watches/Warnings/Advisories...
None.
&&

SHORT TERM...CDC
LONG TERM...Buttler
AVIATION...Stoppkotte

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORTH PLATTE NE
451 AM CDT SAT JUL 30 2016

NEZ004>010-022>029-035>038-056>059-069>071-094-311000-
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-
451 AM CDT SAT JUL 30 2016 /351 AM MDT SAT JUL 30 2016/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WESTERN AND
NORTH CENTRAL NEBRASKA.

.DAY ONE...TODAY AND TONIGHT.

SEVERE WEATHER IS POSSIBLE THIS AFTERNOON AND THIS EVENING.
THE AREA OF CONCERN IS GENERALLY ALONG AND WEST OF A LINE FROM
VALENTINE TO SARGENT.

STORM DEVELOPMENT IS EXPECTED NEAR OR OVER THE BLACK HILLS AND
THESE STORMS WILL MOVE SOUTHEAST INTO PARTS OF WESTERN AND NORTH
CENTRAL NEBRASKA.

LARGE HAIL AND WIND DAMAGE ARE THE THREAT IN MOST AREAS. VERY
LARGE HAIL...2 INCHES OR LARGER...IS POSSIBLE ACROSS SHERIDAN
COUNTY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

ISOLATED THUNDERSTORMS ARE POSSIBLE SUNDAY AND MONDAY. THE RISK OF
SEVERE WEATHER APPEARS LOW BUT AN ISOLATED STORM COULD BRIEFLY
BECOME SEVERE AND PRODUCE LARGE HAIL AND WIND DAMAGE.

HEAT WAVE CONDITIONS ARE EXPECTED MONDAY THROUGH WEDNESDAY WITH
HEAT INDICES RISING INTO THE UPPER 90S TO NEAR 100.

THUNDERSTORMS ARE POSSIBLE WEDNESDAY THROUGH FRIDAY. THE RISK OF
SEVERE WEATHER APPEARS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED ACROSS PARTS OF WESTERN NEBRASKA LATE
THIS AFTERNOON AND THIS EVENING.

&&

GET YOUR WEATHER...HYDROLOGICAL...AND CLIMATE INFORMATION AT
HTTP://WWW.WEATHER.GOV/NORTHPLATTE (ALL LOWERCASE)

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NORTH PLATTE NE
532 AM CDT SAT JUL 30 2016

NEZ008-009-301130-
BROWN NE-ROCK NE-
532 AM CDT SAT JUL 30 2016

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN BROWN AND SOUTHERN
ROCK COUNTIES UNTIL 630 AM CDT...

AT 530 AM CDT...DOPPLER RADAR WAS TRACKING STRONG THUNDERSTORMS ALONG
A LINE EXTENDING FROM 8 MILES NORTHEAST OF JOHNSTOWN TO 6 MILES
NORTHEAST OF ROSE. MOVEMENT WAS SOUTHEAST AT 15 MPH.

RAINFALL OF 1 TO 2 INCHES PER HOUR IS EXPECTED WITH THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
LONG PINE...ANTELOPE PEAK...
KELLER PARK STATE RECREATION AREA AND TWIN LAKES STATE WILDLIFE
MANAGEMENT AREA.

THIS INCLUDES THE FOLLOWING HIGHWAYS...
 HIGHWAY 183 BETWEEN MILE MARKERS 160 AND 174...AND BETWEEN MILE
 MARKERS 194 AND 203.
 HIGHWAY 20 BETWEEN MILE MARKERS 242 AND 254.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THESE STORMS...AND MAY
LEAD TO LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH
FLOODED ROADWAYS.

FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THESE STORMS.
LIGHTNING CAN STRIKE 10 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.

&&

LAT...LON 4274 9982 4220 9926 4212 9937 4268 10002
TIME...MOT...LOC 1030Z 317DEG 12KT 4267 9995 4222 9942

CDC