Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/09/20
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
917 PM CDT Thu Oct 8 2020
Issued at 916 PM CDT Thu Oct 8 2020
Current forecast is on track, therefore no changes made at this
.SHORT TERM...(This Evening through Friday Night)
Issued at 224 PM CDT Thu Oct 8 2020
Main concerns through the period center around temps, winds and fire
danger. The positive PNA pattern looks to start transitioning toward
more of a zonal flow over the next couple days, or at least until a
major system moves into the Northern Rockies toward the end of the
period. For tonight, LLJ will help keep temps up over the eastern
CWA, but the west should see a pretty good wind lull, with some
temps probably falling a bit below the model blend. For Friday a
very warm airmass will spread across most of the region, with quite
warm afternoon temps expected, perhaps even a few records. In the
afternoon, mixing up to as high as H800 looks possible. Given that
expectation, went with the higher guidance numbers, which put us
near the 90th percentile of the model blend MaxTs. The only
spoiler could be elevated smoke, which is predicted to be fairly
widespread by the HRRR smoke model. Friday night lows from the NBM
look fine and were used. Grassland fire danger is likely to be
around high to very high through Saturday given the continued low
RHs in the afternoon. However, will hold off on any headlines for
now as winds don`t look sufficient to meet criteria on Friday.
.LONG TERM...(Saturday through Thursday)
Issued at 224 PM CDT Thu Oct 8 2020
Really not much adjustment for the extended guidance. Plan is to
maintain above average temperatures Saturday, peaking Sunday, with a
stiff southeast pre-frontal breeze (1/2km winds up to 45kts in the
GFS at 06Z Sun) followed by windy conditions in the post-frontal
airmass. Looking at a few hundred j/kg MUCAPE in the mid levels
Sunday afternoon as the front moves into far eastern South Dakota
and western Minnesota, though there will be a strong surface
inversion to contend with. After that, an upper low pivots
northwards and then stalls in central Canada. This means the rest of
the extended should have a steady feed of cooler Canadian/Northern
Rockies sourced airmasses. A weak system or two could ride up over
the Rockies and into our area on zonal flow, but generally at this
timescale, they lack consistency and the flow doesn`t look like a
good set up for moisture for this time of year either.
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 624 PM CDT Thu Oct 8 2020
VFR conditions will prevail across the area tonight and through
the day Friday. Northwest winds will increase into the 15 to 25
knot range Friday afternoon.
***Construction to improve taxiways at both KABR/KPIR terminals
may cause an occasional temporary visibility reduction due
to blowing dust (bldu), mainly during daytime hours UFN.
Area Forecast Discussion
National Weather Service Goodland KS
1000 PM MDT Thu Oct 8 2020
.SHORT TERM...(This evening through Friday)
Issued at 336 PM MDT Thu Oct 8 2020
Weak ridging is in place over the Central High Plains this afternoon
with a shortwave coming into the Intermountain West. Winds this
afternoon will be a little lighter than expected. This leaves
concerns about the extent of fire weather conditions across the
area. The best chance will be areas south of I-70 where low
relative humidity values will be paired with some of the stronger
winds. As far as the amount of time where highlight criteria will
actually be in effect, confidence has gone down.
The HRRR continues to show smoke moving into the area from the south
late this afternoon and into the evening. Dry conditions are
expected to continue through the overnight hours with lows down to
the mid 40s to the mid 50s. The shortwave will make its way through
the area overnight.
Dry conditions will persist tomorrow with flow becoming zonal. This
will lead to a concern for more smoke in the area, coming from
western wildfires. Relative humidity values will be in the single
digits to teens once again for much of the region, however, winds
will be a limiting factor for any fire weather highlights. Highs
will range from the mid 80s to the lower 90s. Lows will be
primarily in the 40s though a few low 50s cannot be entirely ruled
out east of Highway 25.
.LONG TERM...(Sunday through Thursday)
Issued at 308 PM MDT Thu Oct 8 2020
This part of the forecast will transition from record high
temperatures and dry weather to seasonable temperatures with a
chance for rain during the transition.
An upper level trough will swing through the Plains Sunday and
Sunday night. As the trough swings through, a strong cold front
will accompany it. The surface pressure gradient will tighten and
strong 850mb winds will also develop as the front moves through.
Based on the latest data, there may be a brief window when the winds
may gust 50 MPH or more as the front moves through. Am not too
optimistic about rainfall chances due to the lift mainly being tied
to the front as it moves through. Due to the ground being very dry,
am a bit concerned about blowing dust potential as the front moves
through. Even though this will be during the night, there could
still be enough mixing as the front moves through to loft dust into
the air. The winds will gradually decline Monday as the surface
pressure gradient broadens.
In addition to the frontal passage, Sunday looks to be the next
chance for a concern of fire weather conditions being met. Relative
humidity values look to fall earlier in the day than normal, which
is also when the winds will be breezy still. The winds will be the
determining factor. Confidence is greatest for fire weather
concerns to occur over the west half of the forecast area.
Another upper level trough will swing through the Plains mid week.
Models disagree with how deep the trough will be and when it will
move through. Some have as early as Wednesday, while others have as
late as Wednesday night. Strong winds may accompany this frontal
passage too. This trough is quite broad, and rather laminar, so am
not expecting any rainfall with it. However, there may be enough
cool air behind it to bring a hard freeze to the northwestern part
of the forecast area Thursday night.
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1000 PM MDT Thu Oct 8 2020
For KGLD and KMCK, vfr conditions expected through the period. For
KGLD a south wind near 10kts at taf issuance will veer to the
west around 07z by 12z then northwest and north at speeds around
12kts through 00z. After 01z winds will be light and variable.
For KMCK light and variable winds expected from taf issuance
through about 18z then establish a northwest and northerly
direction at speeds around 7kts.
Its possible for KGLD to see some reduced visibilities in smoke in
the 12z-19z timeframe. At this time I wont be introducing any
restrictions given low confidence but its possible that mvfr vis