Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 301220
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
720 AM CDT MON MAY 30 2016

.SYNOPSIS...
Issued at 329 AM CDT Mon May 30 2016

H5 analysis this evening was highlighted by 4 main features
across the CONUS and southern Canada. Closed low pressure was
noted over southern California while a tropical low was located
over southern South Carolina which was the remnants of TS Bonnie.
Across the northern tier of states two shortwave troughs of low
pressure were noted. The first over southern British Columbia and
a second disturbance was located over southern Manitoba. Across
the central CONUS, a mainly zonal pattern was noted, however a
weak shortwave was located over central and western Nebraska. This
feature aided in the development of thunderstorms earlier this
evening. This activity has since weakened and dissipated across
western and north central Nebraska. At the surface, a warm front
was located over northern Nebraska with a surface trough extending
from northern Wyoming to southwestern Kansas. Surface low pressure
was located over north central Wyoming with a secondary, weaker
low noted over southwestern South Dakota. Skies were mostly cloudy
overnight due to an abundance of high clouds in association with
weakening thunderstorms. Temperatures across western and north
central Nebraska were mild overnight with 3 AM CDT temperatures
ranging from around 60 in southwestern Nebraska to the middle 60s
in north central Nebraska.

&&

.SHORT TERM...(Today and tonight)
Issued at 329 AM CDT Mon May 30 2016

The main forecast challenge over the next 24 hours is precipitation
chances. An H5 low will track along the US/Canadian border today
from southern British Columbia to southern Saskatchewan. This
feature will cross the border into northeastern Montana by 00z
Tuesday. This feature will force a pacific cold front into western
South Dakota by this time. East of the cold front, a dryline will
set up across the western sandhills. By late afternoon, with
surface heating and a weakening cap, thunderstorms will begin to
initiate INVOF the dry line in the northwestern CWA. As the front
approaches the dryline by early evening, more widespread
convection will fire in a line from north central into
southwestern Nebraska. Bulk layer shear will be on the order of 25
to 30 kts this evening which would support limited severe
potential. Given the expected linear nature of convection with
this front, the main severe threats will be from damaging winds
and hail in that order. ATTM, the tornado threat appears limited
as backed low level winds will be north of the CWA over South
Dakota. Precipitation chances will transition east with the front
overnight with the highest pops INVOF of the front. I did however
hold onto some low post frontal pops overnight in the west as
there appears to be some post frontal precipitation in association
with the cold pool aloft and the right rear quadrant of a H250 jet
streak which will extend from western Nebraska into eastern North
Dakota. Highs today will be toasty in advance of the front and
increased them to the lower to middle 80s. Lows tonight will be in
the 50s.

.LONG TERM...(Tuesday through Sunday)
Issued at 329 AM CDT Mon May 30 2016

Mid-level low over the Northern Plains will slowly move eastward
Tuesday, and cooler/drier air advects into the forecast area in
the wake of the frontal passage Monday night. Latest NAM generates
a few showers and storms as a subtle vorticity max rotates around
the Northern Plains low and pushes another weak cold front into
the Dakotas and Nebraska Tuesday afternoon. Surface dewpoints only
in the 30s and low 40s will hinder instability and precipitation
chances, so opted to leave the forecast dry for now which is
supported by the latest GFS and Euro solutions. Strong deep layer
subsidence and surface high pressure on the back side of the mid-
level low will result in mostly sunny skies on Wednesday. H85
temps in the 10-15C range will keep high temperatures limited to
the low to mid 70s.

Upper level pattern begins to amplify toward the end of the week as
a stout ridge builds over the western conus. This will result in a
warm up back into the 80s over western and north central Nebraska
for Thursday and through the weekend. A strong shortwave dives
southeast through the Northern Plains late Friday into Saturday,
sending a cold front through the forecast area. Increased
southwesterly flow and strong heating ahead of the front may push
highs close to 90 Friday afternoon, then fall back a few degrees for
Saturday. Isolated QPF is not out of the question Friday evening
along the front, but the forecast will remain dry for now since the
evening model suite is inconsistent with respect to timing and
moisture availability.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 720 AM CDT Mon May 30 2016

An approaching cold front will bring thunderstorms to western and
north central Nebraska later this afternoon and into the evening
hours. For the KLBF terminal, the threat for thunderstorms will
increase after 21z this afternoon. By 00z Tuesday wind gusts up to
45 KTS will be possible with thunderstorms while VISBYS of 2SM are
possible as well. The threat for thunderstorms will end after 04z
Tuesday at the KLBF terminal. For the KVTN terminal, the threat
for thunderstorms will increase after 20z this afternoon with SFC wind
gusts up to 40 KTS possible and VISBYS down to 3 SM with
thunderstorms in the 22Z to 02Z Tuesday time frame. After 03Z Tuesday,
the threat for storms will end at the KVTN terminal with scattered
to broken CIGS of 10000 FT AGL possible there after.

&&

.HYDROLOGY...
Issued at 329 AM CDT Mon May 30 2016

Minor to Moderate flooding continues along the North Platte River
and main stem Platte River. Overnight river stages were 4.3 feet
at Lisco, 8.8 feet at Lewellen, 6.8 feet at North Platte and 7.6
feet at Brady. River stages are expected to remain steady over the
next several days. Along the South Platte River at Roscoe and
North Platte, river levels remain elevated, but no flooding is
expected at this time.

&&

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

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Martin
AVIATION...Buttler
HYDROLOGY...Buttler



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