Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 162327 AAA
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
627 PM CDT TUE AUG 16 2016

.SYNOPSIS...
Issued at 341 PM CDT Tue Aug 16 2016

H5 analysis from this morning had a trough of low
pressure across the midwest states with a ridge up the east coast
and a low amplitude ridge over the intermountain west. Under the
intermountain west ridge, a decent shortwave was noted over the four
corners region. A second shortwave was noted over northern
California. Additional weaker waves were present over southeastern
Wyoming and southern British Columbia...as well as the arrowhead of
Minnesota. At the surface: Weak high pressure was located over
eastern Wyoming. East of this feature, a surface trough of low
pressure extended from northeastern South Dakota, into south central
Nebraska, and southwestern Kansas. Southerly winds were present east
of this feature with northerly winds present west of it. Dew points
this afternoon were generally in the lower 60s, however some mid 40s
to lower 50s were present along a line from Valentine, to Thedford,
to Ogallala and Imperial. Temperatures as of 3 PM CDT, ranged from
86 Ainsworth to 93 at Thedford.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 341 PM CDT Tue Aug 16 2016

Mild conditions continue the next 24 hours. A weak disturbance will
slide across the area early tonight with at least a chance for
isolated convection. Marginal shear and warm temps providing enough
instability that a few storms will be possible. Surface trough is to
the south which lessens confidence for much activity over the area
and the low level jet noses to the south and east of the CWA. Thus
will have low pops this evening with dry overnight. Temps should
fall into the mid 50s to lower 60s by morning with mostly clear
skies. Tomorrow another warm day with weak ridging overhead.
Forecast follows close to guidance although expect dew pts to be a
little higher than guidance which follows closer to bias corrected
guidance. Highs top out in the lower to mid 90s. Afternoon
thunderstorms could clip far SW Neb with the next disturbance, again
low confidence in the development.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 341 PM CDT Tue Aug 16 2016

mid term...Wednesday night through Friday: In the mid range,
precipitation chances Thursday Night into Friday along with
temperatures Thursday are the main forecast concerns. For Wednesday
night: The shortwave located over the four corners will meander to
the northeast on Wednesday. Am expecting convection to initiate
across the central Rockies during the peak heating, however, with
very weak winds aloft, not expecting much of this to make it east
into western Kansas and southwestern Nebraska. Regardless, decided
to maintain forecast continuity and continue a mention of isolated
tsra`s in the southwest Weds eve. Shifting to Thursday: A strong
upper level trough of low pressure aloft will track from the
Northwest Territories into Hudson Bay. This feature will force a
cold front into northwestern Nebraska by early Thursday evening.
Ahead of the front, intense warm air advection will push north from
northwestern Kansas, aided by southwesterly winds. Drier air will
push into west central Nebraska ahead of the front as well. Based on
the 12z NAM and GFS solns this morning, dew points could bottom out
in the 35 to 45 degree range in the sandhills and portions of west
central and north central Nebraska tomorrow afternoon. This would
lead to near critical fire danger conditions for a 3-6 hr window
Thursday afternoon. The statistical guidance came in lower on dew
points as well-albeit not nearly as dry as the graphical model
solns. With this in mind, decided to trend dew points lower from the
inherited forecast, compromising between the statistical guidance
and the graphical model forecast. This led to dew points in the
lower to middle 40s for the western sandhills Thursday afternoon,
which would keep us out of critical fire danger. That being said,
will probably hit the fire danger mention in the HWO with this
afternoon package. For Thursday night into Friday: As mentioned
earlier, a strong cold front will track across western and north
central Nebraska Thursday night into Friday morning. As for
convection along the front, it appears at this time, that we will be
under the influence of a strong capping inversion at least through
early evening Thursday. With this in mind, slowed down the onset of
thunderstorms associated with the front Thursday evening. Thinking
here is that the cold air aloft necessary for convection will hold
off until the overnight hours. As for the severe threat, wind shear
ahead of the front is very weak through 06z Friday, then increases
overnight. ATTM the highest CAPE and shear in advance of the front
is north and northeast of the area, so the severe threat will be
most pronounced north of the forecast area. On Friday, the frontal
boundary will make it into central Nebraska. East of the front, nice
low level moisture return, will push CAPES into the 2500 to 3500
j/KG range Friday afternoon east of a line from O`Neill to North
Platte. Ample shear will be present ahead of the front, so we could
be dealing with some severe storms Friday afternoon and evening in
the east. Post frontal, over northern and western Nebraska Friday
morning into Friday afternoon, a nice H5 shortwave will track from
the panhandle across northern Nebraska. Decent mid level lift, will
become focused from the panhandle into northern Nebraska, and have
increased pops to likely.

long term...Friday night through Tuesday: A second upper level
disturbance will track south from the northern rockies into the high
plains of eastern Colorado and the Nebraska panhandle for Saturday
into Saturday night. Low level easterly upslope winds will be
over-topped by strong mid level lift Saturday into Saturday night,
which will lead to a favorable setup for precipitation in the west
and southwest. Behind this exiting feature, much drier air will push
into the forecast area from the northwest for Sunday into Tuesday.
With the exception of some lingering precipitation in the south for
Sunday, will go with a dry forecast for the latter half of the
extended forecast. After cool highs in the 70s for Saturday and
Sunday, highs will begin to approach 80 to 85 degrees for Monday
into Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 626 PM CDT Tue Aug 16 2016

Isolated thunderstorms are possible this evening along highway
281. This rain is associated with a weak cold front sagging south
through North Central Nebraska.

Other storm activity could form off the Black Hills and move into
Northwest Nebraska this evening. Storm activity in both areas
should dissipate by 06z.

No other storm activity is expected overnight and Wednesday.

&&

.FIRE WEATHER...
Issued at 341 PM CDT Tue Aug 16 2016

Warm afternoons expected Wednesday and Thursday. Highs into the
lower and mid 90s. Dry air will result in RH values in the 20 to 30
percent range. Winds fairly light on Wed however they increase for
Thursday. Elevated fire weather conditions will be possible where
winds gusting to 20 to 25 mph expect Thursday afternoon. Nothing
critical expected at this time however a heighten awareness is
needed. A cold front late Thursday will be cooler conditions for the
weekend with no fire concerns as highs only in the 70s at best.

&&

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

$$

SYNOPSIS...Buttler
SHORT TERM...Masek
LONG TERM...Buttler
AVIATION...CDC
FIRE WEATHER...Masek



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