Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/09/21

AREA FORECAST DISCUSSION

National Weather Service Hastings NE

 654 PM CDT Fri Oct 8 2021

...AVIATION UPDATE...

.DISCUSSION...(This evening through Friday)
Issued at 250 PM CDT Fri Oct 8 2021

Main features to focus on will be the cold front passage Saturday
and dynamic system toward mid-week.

Upper level ridge axis shifts east and upper flow becomes southwest
heading into tonight and Saturday morning, ahead of an amplifying
trough over the Great Basin.

For Tonight, HRRR is already hinting a some possible fog
development on the Nebraska side of the CWA, north of a warm
front, extending east from a surface low near the Colorado,
Nebraska, and Kansas border. Satellite reveals some fairly thick
cirrus that could help keep temps up a bit and perhaps cut some of
our fog potential as well so I will leave out of the forecast for
now, but past experience over the past few mornings will lend
toward keeping a close eye on model trends.

The deep western trough becomes more positively tilted and shifts
east on Saturday begins splitting into two main pieces of energy.
One piece will be focused on the northern Plains while the other
holds back along the western slope of the Rocky Mountains, extending
into parts of the Great Basin. May be some sprinkles west/north,
but bases of clouds will be high and there would be quite a bit of
dry air to overcome, so I will leave out for this forecast. The
cold front will move through our CWA Saturday afternoon/evening,
giving us one more very warm day on Saturday before cooler air is
introduced behind the front. Highs could be a tad tricky as we may
have to weigh between thick cirrus and compressional warming just
ahead of the cold front. Even so, the air behind the cold front
is hardly frigid, and we can expect near normal highs of around
70, give or take.

By Sunday night, the southern piece of energy will aim toward the
central/southern Plains. Latest model trends point toward the focus
being far enough south to keep much of our CWA dry, except perhaps
our far south/southeast. Looks like any parameters pointing toward
severe weather will be focused well to the south in the southern
Plains and western Ozarks.

For Tuesday Night into Wednesday, both ensembles and operational
runs indicate a very dynamic system coming through with a
negatively tilted shortwave trough targeting the northern and
central Plains. A deeply closed low within this wave is forecast
to swing through the central Rockies into the northern Plains by
Wednesday. Ensembles are in general agreement with timing, with
the GFS a bit faster than the ECMWF. Wind speeds will likely be
strong at the surface with this system, but current timing
forecast would put this passage at a relative minimum for any
severe chances if there were to be any. The associated cold front
will bring quite windy conditions to the surface and significantly
cooler air, finally sending us into the below normal realm with
highs near 60 and looking at some potential for lows in the 30s,
at least for parts of our west/north for the last part of the
extended forecast for mid to late next work week.


&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 646 PM CDT Fri Oct 8 2021

High clouds will likely be around throughout the TAF valid period,
but ceilings should remain VFR. The high clouds will likely
prevent any fog from developing again tonight and thus no
visibility issues are expected during this forecast period. The
southeasterly wind tonight will become more southerly Saturday
morning and then westerly by Saturday afternoon, but should remain
light.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

DISCUSSION...Heinlein
AVIATION...Wesely



Area Forecast Discussion

National Weather Service Goodland KS

 944 PM MDT Fri Oct 8 2021

.SHORT TERM...(This evening through Sunday Morning)
Issued at 324 PM MDT Fri Oct 8 2021

RAP analysis has a developing trough over the western CONUS with a
ridge over the central Plains which will slowly move eastward
through the night and the day Saturday. The rest of today will see
elevated to areas of near critical fire weather conditions mainly
along and west of Highway 27. Going into tonight as the trough
progresses eastward associated clouds will move into the area from
west to east with no precipitation expected. Overnight lows are
expected to fall into the low 50s to low 60s as the clouds limit any
radiational cooling.

Into Saturday, high clouds continue to move across the area as
temperatures warm along and south of Interstate 70 as a low develops
with a warm front ahead and trailing cold front behind. High
temperatures will range from the upper 70s across NW portions of the
CWA to the low 90s across the SE portions; it should be noted that
the high clouds may play a role in somewhat reducing the afternoon
high temperatures. The main story for Saturday will be the winds
leading to near critical to critical fire weather conditions over
parts of the CWA. Upgraded Cheyenne County Colorado, Greeley,
Wichita and Wallace counties in Kansas to a Red Flag Warning for
Saturday afternoon; left Kit Carson and Sherman counties in a Fire
Weather Watch for now. Wound up upgrading due to recent trend of
potentially drier dewpoints that guidance was indicating along
with sustained winds of 15-20mph and wind gusts up to 35mph. Kit
Carson and Sherman counties continue to show just slightly higher
dewpoints so kept them in the Watch. Due to these strong winds any
fire that does spark has the potential to spread rapidly. In
addition with the strong winds patchy blowing dust has also been
introduced into the forecast for portions of Cheyenne County
Colorado and Greeley County as winds look to be the strongest over
these areas along with steeper lapse rates in the lowest 0-2km of
the atmosphere on top of the already very dry soil.

Saturday night and Sunday morning, as the low pressure system moves
east the trailing cold front moves through NW to SE across the area.
A small chance of light showers looks possible as it moves through,
however confidence is low due to the drier air in the profile so
have not introduced into the forecast at this time. Overnight lows
look to fall into the low 40s to low 50s across the area with
northwesterly winds of 10-15 mph.

.LONG TERM...(Sunday through Friday)
Issued at 223 PM MDT Fri Oct 8 2021

The initial upper trough in a series moves across the area during
the day on Sunday, followed by weak ridging across the central
high plains on Monday. With the associated surface low over the
southern plains and cooler air moving in behind a front, highs
will be in the middle 60s to lower 70s on Sunday as the bulk of
any precipitation associated with the system remains mainly
across the panhandle region of Oklahoma and Texas. Only the
southern third of the forecast area will see a slight chance of
light rain on Sunday through Sunday evening. Higher pressure
follows along with the upper ridge on Monday and Monday night for
dry conditions and slightly warmer temperatures.

The next deeper upper trough and low center in the series sweeps
through the western U.S. on Monday night into early Tuesday and
lifts out across the central Rockies and High Plains between
Tuesday and Wednesday. Differences are showing up in the position
and timing of these features aloft and at the surface that could
produce a significant change in the timing and amount of
precipitation expected across the forecast area. One concern is a
possible dry slot that may develop as the upper and low lifts out
that may that significantly limit precipitation over the western
sections of the forecast area. If precipitation remains limited,
dry and breezy conditions could bring elevated fire weather
conditions to a portion of the area Monday afternoon.

Cooler temperatures move into the area Tuesday night and
Wednesday that persist through the end of the week. Highs will be
in the upper 50s to upper 60s while lows will cool into the lower
30s to lower 40s as the first freeze for a portion of the area
becomes possible early Thursday morning.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 940 PM MDT Fri Oct 8 2021

VFR conditions forecast for the TAFs. Southerly winds will turn to
the west as a pre-frontal trough moves through. Along and ahead of
the pre- frontal trough LLWS will occur for KGLD, but should remain
west and south of KMCK. The LLWS should end before 12z.

&&

.FIRE WEATHER...
Issued at 324 PM MDT Fri Oct 8 2021

On Saturday near critical to critical fire weather conditions are
expected along and south of Interstate 70 as relative humidity
falls into the upper teens and west to southwest winds gust up
to 35 mph. A Fire Weather Watch is in effect for Cheyenne and Kit
Carson counties in Colorado as well as Sherman, Wallace, Greeley
and Wichita counties in Kansas.

Elevated fire weather conditions are possible along and west of
Highway 27 Tuesday afternoon and Wednesday afternoon.

&&

.CLIMATE...
Issued at 324 PM MDT Fri Oct 8 2021

A record or near record high temperature is possible at the
following location Saturday, October 9:

Hill City..........90 degrees set back in 1965

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from noon MDT /1 PM CDT/ to 6 PM MDT /7 PM CDT/
     Saturday for KSZ027-041-042.

     Fire Weather Watch Saturday afternoon for KSZ013.

CO...Red Flag Warning from noon to 6 PM MDT Saturday for COZ254.

     Fire Weather Watch Saturday afternoon for COZ253.

NE...NONE.
&&

$$

SHORT TERM...TT
LONG TERM...LOCKHART
AVIATION...JTL
FIRE WEATHER...TT
CLIMATE...99



Area Forecast Discussion

National Weather Service North Platte NE

 730 PM CDT Fri Oct 8 2021

.SHORT TERM...(This evening through Saturday night)
Issued at 302 PM CDT Fri Oct 8 2021

Forecast concerns focus on an increasingly active weather pattern
expected to arrive next week. Details pertaining to this can be
found in the Long Term discussion below. Slight chances for light
rain will also exist primarily Saturday for portions of the area.

Afternoon satellite analysis depicts a departing trough across the
Great Lakes region with low-amplitude ridging over southern Texas.
To the west, another approaching longwave trough will bring about
precipitation chances and cooler weather mainly for Day 4 and
beyond.

For tonight, will watch as a modest low-level jet develops ahead of
the next mid-level disturbance to approach the region. This will
usher in warmer, more humid air into the area. This will lead to
increasing cloud cover tonight and keep overnight lows in the 50s to
low 60s. The previously mentioned longwave trough to the west will
lead to a modest disturbance ejecting onto the Central to Northern
High Plains late tonight into early Saturday. This will lead to the
development of a surface low across western South Dakota which will
drag a cool front into the area during the day Saturday. Modest
height falls along with rather nebulous frontogenesis should be
enough to allow isolated showers to develop late tonight through
Saturday morning...mainly for areas along and north of Highway 20.
Cannot completely rule out a few rumbles of thunder as point
forecast soundings indicate some elevated instability, but thinking
this will be rather limited in scope. Latest hi-res guidance are
fairly aggressive in southward extent of shower activity. Am
hesitant to buy into this given copious dry air in the lowest
levels. That said, these frontal boundary tend to "over-produce" and
so will need to monitor this potential in later forecast packages.
This frontal boundary will likely split the area around midday
Saturday with gusty west winds in its wake across the Sandhills and
south to southwesterly winds ahead of it. Did boost temperatures
slightly to account for some downsloping winds in addition to
compressional warming from the advancing front. This puts the area
in the 70s northwest to low 80s south and east. Depending on
progression of the frontal boundary, will need to watch for
redeveloping showers and thunderstorms along this feature during the
afternoon and early evening. Big proponents of this potential are
the RAP and HRRR with the HRRR even advertising a few more robust
storms in the area. Shear would be adequate with effective bulk
shear of 35 to 45 knots but instability is sorely lacking with
MUCAPE values < 500 j/kg. SPC maintains a Day 2 SWO up in South
Dakota and though I think it would be premature to draw this further
south, this idea will need to be investigated further later on.

Following fropa and an invading drier air mass, expect another cool
night Saturday into early Sunday with lows falling into the low 40s
west of Highway 61 to low 50s east of Highway 183. Even so, this
remains nearly 10 to 15 degrees above normal low temperatures for
early to middle October. Expect a breezy start to the day Sunday
with northwest gusts approaching 30 to 35 mph.

.LONG TERM...(Sunday through Friday)
Issued at 302 PM CDT Fri Oct 8 2021

Beginning 12z Sunday. A lot to talk about in the extended forecast
period with an increasingly active weather pattern setting up
leading to increasing chances for precipitation and an appreciable
cooldown expected towards the end of the forecast period.

The period begins with a complicated upper-flow pattern. A longwave
trough the was approaching the area on the day Saturday will
fracture with two prominent systems emerging. The first of these
will be across the Northern Plains where a strong surface low-
pressure system will take shape early Sunday morning. This will
track a cold front through the area bringing an appreciable cooldown
to the area with highs only reaching the 60s to low 70s. Moisture
availability will be rather limited with considerable dry air
throughout the profile therefore little to no precipitation is
expected with this. The lone advocate for precipitation early Sunday
is the Euro with support from its ensemble where enough wrap around
moisture may approach from the north to bring light rain showers to
portions of the Sandhills. Will maintain a slight chance mention to
account for this but any precipitation amounts should remain fairly
light. A fairly compact surface pressure gradient with strong CAA
will combine to produce gusty winds as well during this period. Peak
timing of these features will limit greatest gusts to late morning
and early afternoon as the gradient relaxes in latter half of the
day with dry conditions expected. The second shortwave of prominence
will track across the Southern Plains along the baroclinic zone in
proximity of the aforementioned cold front which will have stalled
across Oklahoma by this time. A second surface low will take shape
in the Texas and Oklahoma panhandles and track east through the late
afternoon and evening into early Monday morning. At this time, it is
believed the precipitation associated with this system will remain
south of the area with little in the way of sensible weather in the
local area.

After a brief return to dry weather for the daytime Monday with a
slight warmup thanks to shortwave ridging, attention then turns to
the next longwave trough as it approaches from the west late Monday.
A large, digging trough will dive southward along the west coast and
begin to cutoff by early Monday. As with most cutoff systems,
details remain murky at this range but fairly consistent model
consensus depicts this feature ejecting as a negative tilt trough in
the Tuesday/Wednesday timeframe. Precipitation looks to begin as
early as Tuesday in the form of WAA showers before better upper-
level dynamics arrive by early morning Wednesday. Latest trends have
boosted warm air in the system and thus decreased confidence in much
if any snow in the area. The large player in this is the absence of
cold air in the wake of a lead impulse. Thermal profiles across the
area appear to be unfavorable for much more than a few wet
snowflakes across portions of the Nebraska Panhandle, therefore,
thinking remains steadfast that this event will be a rain event for
the entire forecast area. Regarding the potential for
thunderstorms...strong low-level moisture advection will precede the
deepening low and will push surface dew points into the upper 50s to
low 60s across mainly our eastern zones. Though some modest mid-
level lapse rates may exist, spatial coverage of these may be
limited which in turn will limit overall scope of instability in
place. Ensemble guidance paints a picture where instability should
remain fairly weak with less than 20% probability of seeing CAPE
values exceeding 1000 j/kg. Given this, believe the threat for
strong to severe thunderstorms to be fairly low this far north even
with strong shear in place. Regarding forecast precipitation
amounts...given strong lift do anticipate widespread wetting
precipitation with even the NBM 25th percentile showing much of the
area seeing at least a tenth of an inch of water. Latest guidance
from WPC suggests anywhere from a half an inch in the south to
nearly two inches in the north of liquid equivalent precipitation.
This will likely be refined in the coming days but expect locally
heavy rain in spots. Though some timing discrepancies remain,
confidence is medium in greatest window for precipitation, high in
being primarily a rain event, and high regarding the potential for
strong winds to accompany the system. Given anticipated rapid
deepening of the surface low on Wednesday, low-level mass field
response will ramp up considerably. Utilizing the model blend, the
gust forecast calls for many locations to see 30 knot plus wind
gusts late Wednesday and again Thursday. Do believe this may be a
bit conservative with some guidance advertising potential for some
High Wind Warning criteria being met (sustained > 40 mph for at
least one hour or any gusts exceeding 58 mph). This is far from a
slam dunk so continue to monitor the forecast if susceptible to
strong winds. Temperatures for Tuesday and Wednesday remain in flux,
largely due to discrepancies in timing of the system. For now, can
expect to see a mild day Tuesday with much cooler temperatures
Wednesday...likely a 10-15 degree drop day-to-day...with high
temperatures running below normal for Wednesday and Thursday. Lows
may fall into the low 30s for west of Highway 83 on Wednesday and
for the entire area on Thursday so the frost potential will need to
be monitored as well.

High pressure will work in Friday into the weekend which should
bring about a return to dry weather but will also set us up for more
Fall-like temperatures with highs in the 50s-60s and lows in the
30s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 727 PM CDT Fri Oct 8 2021

VFR conditions will prevail through Saturday across all of western
and north central Nebraska. Some mid and high level overcast along
with some virga is expected at times. Winds will generally remain
15 kts or less.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...NMJ
LONG TERM...NMJ
AVIATION...Taylor