Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/12/20
Area Forecast Discussion
National Weather Service Denver/Boulder CO
922 PM MDT Sun Oct 11 2020
.UPDATE...
Issued at 840 PM MDT Sun Oct 11 2020
Winds have decreased for the night in the foothills and plains
with boundary layer decoupling and will increase again with mixing
tomorrow. Winds remain gusty in the mountians and will overnight.
Northwest flow and lee troughing will mean another windy day,
though winds are not expected to be quite as strong as today. The
area will be dry and warm again, so fire danger remains widespread
and critical. We have issued another Red Flag Warning for
tomorrow afternoon. Some light snow fell on the fires in the
mountains and suppressed smoke production today, and will continue
to do so tomorrow. Transport winds also turned more westerly and
these factors should give us a short break from the smoke that has
impacted the area for the past few weeks. We updated the smoke
grids by reducing the area impacted by smoke to only those close
to the fires and along the Colorado- Wyoming border, east of the
largest mountain fires. Otherwise, the forecast remains on track
and no changes were made.
&&
.SHORT TERM...(This evening through Monday)
Issued at 316 PM MDT Sun Oct 11 2020
Lots going on right now as a vigorous trough moves across
Colorado. Winds are peaking ahead of the shower band, with the
strongest winds across Denver now. There was some smoke pooled
right behind the front, but it`s been overtaken by a lot of
blowing dust. Winds are starting to diminish north of Interstate
76 and the improvement will be dropping south across the area by
early evening.
Meanwhile, the mountains wound up getting pretty widespread
precipitation west of the Front Range and a little ways down the
east slopes. It`s mainly been light, but came fast enough for a
little accumulation over the higher passes. This looks to have a
couple hours left as well. The downslope will prevent anything
around Denver, though there could be a few sprinkles out near the
eastern border in the late afternoon.
The low level winds will decrease some this evening. Still not
sure about a possible northerly surge behind the trough that could
produce a period of lighter north or northeast winds into Denver
for a while in the evening. Otherwise, it will remain windy in the
mountains and breezy on the plains through Monday. There is
potential for some mountain wave amplification as warm advection
aloft sets in overnight. It`s a pretty sheared environment, but
it`s probably at least enough to keep speeds up over the ridges
and higher east slopes.
Warming aloft and low level southwest flow will bring temperatures
back up to near today`s levels on Monday afternoon. Our moisture
will be long gone, and humidities will be low enough for another
Red Flag Warning for the foothills, South Park, and the plains.
Jackson and Grand counties will also be close, the humidities will
be a bit above Red Flag criteria but it will be another dry and
windy day. The higher mountains will stay windy and the moisture
that fell will be going away quickly.
.LONG TERM...(Monday night through Sunday)
Issued at 316 PM MDT Sun Oct 11 2020
Extended period of dry conditions expected over the next several
days. Forecast period will start off with predominantly west-
northwest flow aloft, with little in the way of moisture. It will
be windy, with 700mb wind speeds near 30-40kt and the potential
for another mountain wave Monday night. Cross-sections show cross-
barrier flow of 30-50kt, so thinking is that gusty winds will
continue across the more vulnerable areas of the high terrain and
along the northern foothills.
Temperatures Tuesday will be a bit warmer as mid-level
temperatures warm a couple of degrees compared to Monday.
Highs in the mid-upper 70s will be common across the plains. It
will continue to be windy across much of the Front Range and
northern foothills, with the strongest winds along the CO/WY
border, where flow is strongest. Winds will continue through
Tuesday night with another chance for more robust mountain wave
development. Some deterministic guidance is quite bullish with the
potential for very strong winds overnight. Winds overnight are
progged to be nearly due west, with 40-60kt 700-500mb flow.
By Wednesday, winds will likely spread across portions of the
plains, especially along the WY/NE borders. Very strong WNW flow
is expected to continue ahead of an approaching 100kt jet at
500mb. There could be just enough low-level moisture to produce a
few showers, but continued fire danger will be the bigger concern
given the duration and magnitude of wind gusts across the high
terrain and northeast plains. A cold front will then quickly push
south through the area late Wednesday into early Thursday,
dropping temperatures substantially. Better confidence in cool
highs Thurs across the plains, with highs in the low/mid 50s.
Cold air should be short lived as the deep trough settles to our
east over the Great Lakes Friday into this weekend. Temperatures
will moderate back to near normal values for the plains (upper
60s) both Friday and Saturday, with less wind expected. More
uncertainty in what the pattern does beyond Saturday, where there
is little run to run consistency across the guidance.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 840 PM MDT Sun Oct 11 2020
Winds tonight will be late to follow normal diurnal patterns due to
a northerly push behind today`s strong westerlies. Winds are
expected to begin turning quickly after midnight to easterly around
7Z and then southerly by around 10Z. Winds have decreased
significantly due to decoupling and normal speeds can be expected to
prevail overnight. More gustiness in west-northwest winds can be
expected tomorrow afternoon with mixing, however not nearly as
strong as seen today. Skies have cleared and should remain clear
overnight. The cloudiness upstream in the synoptic flow won`t reach
the area until tomorrow. Light snows on the mountain fires limited
smoke production today and will do so again tomorrow, which reduced
the impact of smoke in the area significantly. Furthermore, more
westerly transport winds have carried most of the remaining smoke
well away from the terminals. The HRRRx near surface smoke product
is available again and suggests that the area may remain fairly
clear of smoke for the next two days. The RAP near surface and
vertically integrated smoke products also support this, as well as
the NASA GMAO biomass model. We have removed smoke from the TAFs and
any visibility restrictions, and will continue to monitor the
situation.
&&
.FIRE WEATHER...
Issued at 316 PM MDT Sun Oct 11 2020
Winds will decrease over the lower elevations this evening. It
will be breezy all night but humidities will be higher. For the
mountains there will be some decrease in the wind, but it will
remain windy. The higher east slopes of the Front Range may
continue to have very strong winds at times through Monday. Drier
air moving in will result in lower humidities and Red Flag
conditions over the foothills and lower elevations on Monday
afternoon.
Elevated fire danger will continue through at least Wednesday,
with dry and windy conditions expected through mid-week. Across
the higher terrain, gusty winds are expected even at night, with
mountain wave potential both Monday and Tuesday nights. More
widespread wind is expected Wednesday across the plains ahead of a
strong 500mb speed max. Humidity values through Wednesday are
forecast to be just higher than red flag conditions. However,
still a lot of concern for the next several days given the
longevity of the gusty winds, especially across portions of the
Front Range and northern foothills.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 6 PM MDT Monday for COZ214>216-
238>251.
&&
$$
UPDATE...Direnzo/Kriederman
SHORT TERM...Gimmestad
LONG TERM...Hiris
AVIATION...Direnzo/Kriederman
FIRE WEATHER...Gimmestad/Hiris
Area Forecast Discussion
National Weather Service Grand Forks ND
951 PM CDT Sun Oct 11 2020
.SHORT TERM...(Tonight through Monday night)
Issued at 949 PM CDT Sun Oct 11 2020
Cold front located near Warroad to Bagley to just west of Wadena
at 0230z. Area of showers and t-storms continue to move north-
northeast along the boundary as it moves east. Severe threat ended
around 0130z so watch has been dropped. Remaining showers and
t-storms will exit the eastern fcst area 07z-09z period.
General clearing expected overnight in eastern ND with winds
diminishing as well into the 8 to 15 mph range.
Lows looking ok at this point with upper 30s to low 40s from west
to east.
Looking at winds for Monday, they look sub advisory but a bit
breezy west winds HRRR indicates in the 15-25 mph range in the
aftn. Temp fcst of upper 50s to mid 60s.
.LONG TERM...(Tuesday through Sunday)
Issued at 300 PM CDT Sun Oct 11 2020
Opportunities for impactful weather will consist of a few midweek
showers and maybe a period of light snow proximal to Lake of the
Woods late week.
Northwest flow will prevail on Tue, and with 850 ensemble winds
progged at 30 kts or better, we could be looking at 20-30 mph near
sfc winds along and west of the valley, given efficient mixing.
During this time northern high plains low will be advancing to the
east in developing zonal flow, increasing shower chances during the
day on Wed. Guidance has been converging to a more POPful solution.
Earlier in the day, some areas across the north could experience a
few snowflakes mixed in with the liquid.
Cyclonic flow remains through the end of the week, with Lake of the
Woods on edge of area of scant moisture, but nevertheless it could
combine with -8C or colder 850mb temps and the proper wind fetch to
present a chance of a little lake enhanced snow shower activity.
Snow plumes picking up on chance for minor accum. vcnty. KBDE Fri.
After that the cooler air lingers over the entire region, with 850
mb temps remaining in the -4 to -8C range, limiting high temps to
the 40s by then, with lows near or below freezing.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 707 PM CDT Sun Oct 11 2020
VFR thru the pd. Exception will be locally MVFR vsbys in t-storms
BJI area thru 03z. Strong south winds diminishing in MN and
turning west all areas overnight, but in the 8 to 15 kt range.
West winds increasing to 15-25 kts Monday midday and aftn. Cloud
deck in the 4000-8000 ft agl range then clearing spreading east
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
SHORT TERM...Riddle
LONG TERM...WJB
AVIATION...Riddle
Area Forecast Discussion
National Weather Service Memphis TN
644 PM CDT Sun Oct 11 2020
.DISCUSSION...
Updated for aviation discussion
&&
.PREV DISCUSSION... /issued 346 PM CDT Sun Oct 11 2020/
DISCUSSION...
Clouds have hung tough across the Mid South today and there has
been some small breaks over the northwestern portions of the
forecast area. Expect the clouds associated with the remnants of
Delta to continue to stick around through the evening. Low clouds
and stratus is expected to be around overnight and some patchy
fog is also possible. A front will approach the area tomorrow and
essentially sweep out the humid air. A few light showers will be
possible over the northeastern portions of the CWA as the front
moves through. Nearly zonal west-northwest flow will prevail
through Wednesday, with sunshine and southerly return flow warming
Wednesday afternoon`s temps to around 80. A stronger front will
move through the area on Thursday. This will bring a chance of
rain but a shot of cooler air going into the weekend.
&&
.AVIATION...
VFR/MVFR deck across areas mainly along and east of the MS River
this evening. Some clearing taking place across parts of NW TN.
Big question tonight is whether the deck continue to break up
which may allow fog/low clouds to develop with the potential for
LIFR conds especially at KMKL and KTUP as depicted by the latest
HRRR run. For now added some IFR vsbys due to fog at KMKL but
kept the MVFR deck overnight at KTUP. KMEM should improve to VFR
over the next few hours and remain VFR overnight along with KJBR.
A front will move through on Monday with perhaps a few SHRAs and a
period of MVFR cigs. Expect wind to become gusty from the W/NW by
the afternoon.
SJM
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Monday)
Issued at 324 PM CDT Sun Oct 11 2020
Early this afternoon an upper level trough was located across the
central Rockies. At the surface a lee surface trough was located
across the central and southern high plains. The pressure gradient
east of the lee surface trough across central and eastern KS has
caused southerly winds to increased to 15 to 20 MPH with gusts of
25 to 30 MPH through the late morning hours and will continue
through the afternoon hours.
Tonight, as the upper trough across the central Rockies, lifts
northeast into the central Plains a line of thunderstorms will
develop along the front across MN and north central IA due to
surface convergence ahead of the surface front and and DCVA ahead
of the H5 trough. The line of storms will backbuild southwest
towards north central KS along the NE border during the early
evening hours. There still remains some uncertainty if storms
will develop along the front across north central KS this evening.
The HRRR and ARW-NMM west CAMs keep most of the convection north
of the CWA. Meanwhile, the 3KM NAM and ARW-NMM east CAMS do show
thunderstorms backbuilding southward across north central KS this
evening and spreading rapidly east across the CWA during the late
evening and into the very early morning hours of Monday. At this
time I used a blend of the CAMs, which matched the RAP model and
have the highest pops north of I-70. If storms manage to develop
across the CWA, ahead of the front, MUCAPEs will be 1000-1500
J/KG with effective shear of 30 to 40 KTS. Thus, the combination
of instability and vertical windshear may produced some organized
updrafts within the line of storms that may produce large hail,
especially any updrafts that exhibit mid-level rotation. Damaging
wind gusts may be the primary hazard if the line of thunderstorms
back build into the western counties of the CWA through the
evening hours and shifts east.
Behind the front there will be rapid pressure rises and strong low-
level CAA as the H5 trough axis shifts east-northeast cross the
central Plains. Several CAMs forecast north-northwesterly 925MB
winds of 50 to 60 KTS. I expect a window of 2 to 3 hours after
FROPA for wind gusts to be 40 to 45 KTS (45 to 55 MPH) just behind
the front. I think the PBL may decouple just enough to prevent the
momentum transfer of 50 KTS winds to the surface but this will
have to be watched by the next shift, just in case low-level lapse
rates remain steep enough after sunset. Therefore, I have
expanded the wind advisory to cover the entire CWA Tonight. The
front will exit the CWA by 10Z and winds will subside from west to
east across the CWA during the early morning hours of Monday.
Overnight lows will be in the mid 40s across north central KS to
the lower 50s across the northeast counties.
Monday, northwest winds will be breezy during the morning hours but
will slowly back more to the west and subside under 10 KTS by late
afternoon. Highs on Monday will be cooler but still pleasant with
highs in the lower to mid 70s.
.LONG TERM...(Monday night through Sunday)
Issued at 324 PM CDT Sun Oct 11 2020
Expectwest-northwest mid and upper level flow across the Plains
through through the extended forecast period with dry conditions.
Afternoon high temperatures will warm into the mid to upper 70s
on Tuesday with lower to mid 80s by Wednesday, ahead of the
surface front. An upper level trough will dig southeast across the
Plains Wednesday into Wednesday night and this will cause a cold
front to push southeast across the CWA late Wednesday afternoon
into Wednesday evening. Thursday will be much colder with highs
only reaching the upper 50s to lower 60s with only a slow
moderating trend into next weekend. There may be a chance for
frost Friday morning with lows in the lower to mid 30s but we are
approaching the average first freeze date.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 658 PM CDT Sun Oct 11 2020
Winds continue to be the main aviation concern for this period.
Gusty winds will weaken allowing for LLWS to develop this evening
ahead of a surface cold front. SSE winds shift to the NNW with
strong wind gusts of 40-45 kts behind the front. Showers and
storms are possible as the front passes, but the better chance for
precip looks to be north of terminals. Winds and wind gusts
weaken through the day on Monday.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 PM this evening to 3 AM CDT Monday for
KSZ010>012-022>024-035>038.
Wind Advisory from midnight tonight to 5 AM CDT Monday for
KSZ026-039-040-054>056-058-059.
Wind Advisory until midnight CDT tonight for KSZ008-009-020-021-
034.
&&
$$
SHORT TERM...Gargan
LONG TERM...Gargan
AVIATION...Flanagan