Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/02/20
Area Forecast Discussion
National Weather Service Bismarck ND
948 PM CST Tue Dec 1 2020
.UPDATE...
Issued at 945 PM CST Tue Dec 1 2020
The forecast for tonight remains on track. Extensive cloud cover
across western and central ND, with increasing low clouds east
next few hours. Will keep some low POPs going through the evening
southwest and south central, with a few indications of isolated
precip west (via web cams and a TRACE reported at KHEI).
UPDATE Issued at 653 PM CST Tue Dec 1 2020
Main mid to upper level forcing will occur this evening in
conjunction with a saturated boundary layer, so will maintain low
POPs through this evening, then go dry after midnight. Other
forecast elements on track for tonight.
UPDATE
Issued at 520 PM CST Tue Dec 1 2020
Quick update to expire the wind advisory southwest. Winds have
tapered off and will continue to do so over the next few hours.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 243 PM CST Tue Dec 1 2020
The main concerns for the short term period are strong northwest
winds in southwest North Dakota this afternoon, a slight chance of
light snow across western North Dakota this afternoon through
tonight, and a slight chance of light freezing drizzle across
central North Dakota tonight into Wednesday morning.
A mid level trough axis lies from Saskatchewan toward the Central
Rockies this afternoon, with embedded circulations in the process of
closing off over southern Saskatchewan and Colorado. At the surface,
a north-south oriented cold front is advancing eastward across North
Dakota this afternoon, though at a slower pace than expected. Behind
the front, strong boundary layer mixing is supporting 30-40 kt
northwest surface wind gusts, strongest in far southwest North
Dakota where sustained winds around 30 mph have been observed. The
ongoing Wind Advisory looks to be in good shape.
Earlier today, the cold front was being followed by a band of light
to moderate snow in eastern Montana. However, this precipitation has
all but dissipated prior to reaching across the border. It does
appear there is currently some remnant light snow along and south of
Highway 12 in Bowman County. Meanwhile, as the southern Saskatchewan
cut-off low drifts southward, some light rain or snow may develop
across western North Dakota later this afternoon and into the
evening, with the highest probabilities of this occurring in the
northwest. Little to no accumulation is expected.
Later tonight, as the closed mid level low is forced to the south-
southwest by its neighboring closed southern low and a downstream
blocking high, low level saturation is forecast to expand across the
region. Several consecutive runs of the HRRR and RAP suggest that
the saturated layer may become deep enough and contain enough upward
vertical motion to support some light freezing drizzle across
central North Dakota. The main forcing mechanisms appear to be
deformation zone dynamics and isentropic ascent, with upglide
actually occurring from north to south due to the closed mid level
low. Other guidance is not as bullish on this potential, with
saturation layer depth more shallow, weaker lift, and higher
ceilings. Therefore, we are limiting this potential to a slight
chance for now. Even if the HRRR and RAP do verify, this does not
appear to have the makings of a higher-end freezing drizzle event.
We also maintained a slight chance of precipitation across western
North Dakota through tonight, but forcing is more questionable there
and cooler temperatures aloft increase probabilities for
hydrometeors falling as snow.
High pressure will begin to build over the region on Wednesday, but
expect a cooler day with highs in the lower to mid 30s, still near
average for this time of year. Cloud cover is expected to decrease
through the day, but models are known to dissipate large expanses of
low clouds too quickly during the cold season.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 243 PM CST Tue Dec 1 2020
Mild and dry weather is expected to dominate the long term period.
Western CONUS longwave ridging is forecast to hold through early
next week, with its influences reaching as far east as the Northern
Plains. There is some evidence that a shortwave or two embedded in
northwest flow aloft may pass nearby this weekend into early next
week, but they look rather weak and dry, and would likely only cause
a slight uptick in winds. In fact, both the GEFS and ECMWF ensemble
display a 10 percent or less chance of measurable QPF Thursday
through Tuesday. There is also strong ensemble support for above
normal temperatures, with mean 850 mb temperatures well above
freezing and very few sub-freezing outliers in the GEFS. Whichever
days over this time period contain mostly sunny skies and westerly
winds, which may be most or all of them, will likely see daytime
highs outperform model consensus, which is already in the upper 30s
to near 50. Looking ahead, there are hints of a cooling trend and a
more active pattern by the end of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 653 PM CST Tue Dec 1 2020
A cold front moving through the region will bring gusty northwest
winds, MVFR cigs, and a slight chance of drizzle, freezing
drizzle, or light snow across western and central North Dakota
this evening. The probability of precipitation remains low so
will keep out of the TAFs at this time. MVFR cigs will continue
into Wed morning, before clearing from north to south during the
day Wednesday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...Hollan
LONG TERM...Hollan
AVIATION...NH
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 241 PM CST Tue Dec 1 2020
Today through Thursday:
Uneventful weather still expected for the next 7 days. Biggest
forecast concern will be how far east the cold front travels
before it loses shape and mixes out. One front has already stalled
out over central Nebraska. There isn`t much temperature difference
with that front, but there is a noticeable wind difference. As of
2 PM, the front stalled out between O`Neill and Norfolk. A strong
cold front is currently located in western South Dakota and will
move into eastern Nebraska in the overnight hours. How far east
and south it goes will be dependent on the low pressure systems on
the leeside of the Rockies. HRRR and RAP 500mb analysis show two
separate low pressure minima. These mimima are expected to
continue their south-southwest trek along the Rocky Mountains.
Model guidance suggest they`ll stall out in northern Texas and
northern New Mexico and undergo a bit of the Fujiwara effect
(essentially, the low pressure centers will pinwheel around each
other). Eventually, the system will move somewhat northeasterly
and bring a surge of moisture with it. That precipitation should
remain well south of Nebraska and Iowa with snow expected in
Kansas and Missouri. Lift and moisture are lacking in the area so
precipitation isn`t expected.
Depending on your location in eastern Nebraska or western Iowa,
Wednesday may be your coolest day of the week or Thursday.
Locations to the northwest of the cold front will have their
coldest day Wednesday. This is likely to be areas north and west
of a line from Columbus to West Point to Monona. Though the
differences won`t be huge, probably within 5 degrees or so on each
day. Temperatures at the 850mb level will increase from about -3C
to 0C which should lead to slight warmup on Thursday. Linger cloud
may limit temperatures on Thursday in southeast Nebraska and
southwest Iowa.
Friday through Monday:
The pattern is still somewhat convoluted through the weekend and
into Monday. In general, a dry and warm pattern will dominate the
mid-range as a ridge of high pressure will build over the West
Coast. Northwest flow and increased heights over the area may
result in temperatures in the 50s on Monday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 516 PM CST Tue Dec 1 2020
VFR conditions will prevail through the period.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Fajman
AVIATION...DEE
Area Forecast Discussion...CORRECTED
National Weather Service Pueblo CO
345 PM MST Tue Dec 1 2020
.SHORT TERM...(This evening through Wednesday)
Issued at 325 PM MST Tue Dec 1 2020
Currently...
Cloudy, cold and windy weather prevailed across most of the region
at 2 pm this afternoon. The only exception was the San Juan region
where it was partly cloudy per sat imagery and winds were relatively
light. Some sun was note over the far eastern plains, but it was
windy and cold. Along the I2-5 corridor region, and especially along
the eastern face of the mtns, it was cloudy, cold windy and was
snowing in many locations. As one of my colleagues stated "an overall
yucky day".
Tonight and Tomorrow...
The yucky-ness isn`t going to go away anytime soon. major trough
moving over the region will keep it cold and windy through most of
this period. High res guidance is still indicating it will get quite
windy over parts of El Paso county, especially the northeastern
sections of El Paso county late this afternoon and evening. Gusts to
45 to 55 mph will be possible per latest runs of the HRRR guidance.
There may be some snow falling when this occurs, but is should not
be all that heavy. Nonetheless it will be quite miserable for anyone
who has to be out an about in this weather.
For the rest of the plains, it will remain on the breezy to windy
side throughout the night, although winds should be lessening
somewhat as the night progresses.
As for snow... the best chance will be this evening along the
mtns/plains interface from south of Canon City to the NM state line.
Several inches of snow will be possible, and I would not be too
surprised if some areas see a half foot of snow.
Ambient temps tonight will fall into the upper teens to low 20s, but
with the winds, it will feel like it is in the single digits and
teens.
For tomorrow...It will be colder than today, and its going to
continue to be rather windy, with winds in the 25 to 35 mph range
over a majority of the plains. Best overall chance of snow showers
tomorrow will be along the CO/NM-OK border areas and along the
CO/KS border, mainly south of Lamar. This precip will due to a
combination of upslope flow over the Raton Mesa and possibly wrap-
around precip around the large circulation of the cyclone which
will be over the TX Panhandle region. With northerly flow
continuing over the Palmer Divide, some light snow will be
possible over N El Paso county.
Max temps tomorrow will only in in the 20s and 30s plains and valleys
and tens in the mtns. The winds will make it feel much colder,
especially over the plains. /Hodanish
.LONG TERM...(Wednesday night through Tuesday)
Issued at 325 PM MST Tue Dec 1 2020
...Blustery Wednesday and Thursday...
Wednesday night-Thursday night...Latest models trending into better
agreement of an upper low across the Oklahoma Panhandle Wednesday
afternoon slowly lifting northeast Wednesday night and Thursday, as
secondary energy digging across the Central Rockies Wednesday
continues south across the Southern Rockies through the day
Thursday. This will keep moderate east to northeast flow aloft
across the region Wednesday night, with flow becoming more northerly
through the day Thursday, allowing for slowly warming temperatures
through out the day. The passing secondary energy will send a
secondary front across eastern Colorado keeping breezy northerly
winds across the plains through the overnight hours, and combined
with slowly decreasing clouds from west to east, may keep the
ambient temperature from dropping too much overnight across the
far southeast plains, though the apparent temperature will sure be
noticed. At any rate, will likely see overnight lows in the teens
across the plains, with single digit readings above and below
zero across the higher terrain, coldest at the peaks and high
mountain valleys. As for precipitation, could continue to see a
few light snow showers/flurries across the Pikes Peak region and
across the southeast mountains Wednesday evening, with the
potential for some wrap around precipitation across the far
southeast plains. For Thursday, drier and warm air continues to
filter into the region from the north, leading to expected dry
conditions. However, Thursday looks to be a "blustery" day with
expected breezy northerly winds and temperatures slowly warming
into the 30s to lower 40s across the plains, and mainly in the 20s
and 30s across the higher terrain. Thursday night will continue
to be dry, with continued warming aloft owning to milder overnight
lows in the teens and 20s for areas over and near the higher
terrain, save for the normal cool pockets across the San Luis
Valley and along the lower Arkansas River Valley.
Friday-Sunday...Despite model differences on where secondary energy
across the Southern Rockies ends up, the main story will be upper
level ridging building across the Great Basin and into the region
into the weekend. This will keep moderate northerly flow aloft
across the area on Friday, which slowly weakens through the weekend.
With that said, expecting dry conditions, with breezy afternoon
winds, especially across the plains, where warming temperatures will
lead to good mixing and increased fire danger. Highs through the
weekend look to warm back to at and above seasonal levels in the 50s
across the plains, and mainly 30s and 40s across the higher terrain,
with at and above seasonal overnight lows.
Monday-Tuesday...Again, longer range models indicating differences
on location and strength of energy trying to break down the rex
blocky pattern across the Conus. With that said, blended model
solution keeps dry weather with at and above seasonal temperatures
in place across the region through early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 325 PM MST Tue Dec 1 2020
Breezy to windy conditions will continue at the KCOS and KPUB
through tomorrow afternoon. Cant rule out some passing snow showers
but do not expect any accumulations. Brief periods of MVFR could
occur with the snow showers and lower cigs.
KALS...winds will be less over this region but as a trough moves
over during the nighttime hours, we could see some periods of lower
cigs and snow showers. VFR anticipated tomorrow.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HODANISH
LONG TERM...MW
AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Riverton WY
754 PM MST Tue Dec 1 2020
.UPDATE...
Issued at 754 PM MST Tue Dec 1 2020
The snowfall over the Wind River Basin, Lander Foothills, and
adjacent east slope of the southern Wind River Mountains has taken
on an upslope pattern. These conditions will likely continue for
at least another hour or two. Increased snowfall in these areas to
account for this. It appears that Riverton could end up with 2
inches,, and lander close to three, with the adjacent mountains
receiving 4 to 5 inches. With the established snow cover in place,
and a positively tilted ridge building in from the west, patchy
fog will likely occur in the Wind River Basin and possibly the
Lander Foothills late Wednesday night and Thursday morning, so
added the fog into the forecast.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 740 PM MST Tue Dec 1 2020
|The latest storm system has moved through the forecast area early
this morning and is now over southeast WY. Slightly unstable
north-northwest flow follows the system as surface pressures
rise. Strongest wind is east of the divide in the Bighorn Basin
and across much of Johnson County where wind gusts were over 50
mph earlier. Light showers continue from northern into central
WY late in the morning. The current pattern will continue through
the afternoon hours, with some showers moving into Sweetwater
County as well as off of South Pass. A secondary mid-level low is
expected to follow this system and move from eastern Montana into
eastern WY this evening. This low is expected to increase snow
showers along and east of the divide by midnight as it increases
instability and concentrates available moisture into favored
upslope areas such as Lander to Beaver Rim. The HRRR is especially
showing some increased showers over Casper to Lander by 8pm, then
moving south into Sweetwater County by midnight. Some areas may
see up to an inch of snow as a result. So, cool breezy north flow
will continue into early Wednesday morning with isolated to
scattered snow showers.
The mid-level low moves over southeast WY Wednesday morning,
dragging the area of isolated showers into southern WY with
surface high pressure over the area. Clearing skies will occur
from north to south Wednesday afternoon with seasonal temperatures
and decreasing wind. Upper-level high pressure over the northwest
US will then fold over on Wyoming Wed night into Thu morning,
likely strengthening surface inversions in the valleys and basins,
keeping some low temperatures in western WY below zero.
.LONG TERM...(Thursday through Tuesday)
Issued at 740 PM MST Tue Dec 1 2020
The upper high that has been progged for the last several model
runs will begin its hold over the PACNW/Northern Rockies Thursday.
Below normal temperatures remain in the forecast, due to
inversions keeping the cold air trapped in the valleys and basins.
Fog will remain a possibility in the western valleys Thursday
Morning/Friday night/Saturday morning, but confidence has waned in
any fog lasting for more than 2 days at this point (Thursday &
Friday mornings). The upper high will keep conditions dry, with
light winds and mostly clear skies through the weekend. Models
have begun to prog a system weakening, as it runs into the ridge.
This system will have no impact to the Cowboy State, but could
break down the ridge and be a precursor for a more zonal flow
pattern next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 740 PM MST Tue Dec 1 2020
West of the Continental Divide...KBPI/KJAC/KPNA/KRKS Terminals
Expect VFR conditions across the terminals during the TAF period.
Snow showers and associated obscurations will linger in much of the
mountains through 03z Wednesday. Gusty winds will continue for all
locations except KJAC, with gusts to around 30 knots. These winds
should diminish between 02Z-06Z across the terminals. Dry conditions
expected on Wednesday with some breezy northeast winds in the
afternoon across the south.
East of the Continental Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals
Expect VFR conditions for all terminals through the period, though
brief periods of MVFR could occur under snow showers. Snow showers
and the gusty north winds will linger in the north, including KCOD,
through 02Z Wednesday. Isolated to widely scattered showers will
continue in the KCPR area through tonight and most of Wednesday
morning. These showers will exit the area around noon. Wednesday
afternoon will be cold and dry, with a breezy northeast wind from
Natrona to the Green Mountains.
Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.
&&
.FIRE WEATHER...
Issued AT 740 PM MST Tue Dec 1 2020
Current storm system has moved to the southeast and brought
isolated to scattered showers along with cool north to northwest
wind. Showers are expected along and east of the divide through
Wednesday morning, with the Lander to Beaver Rim area possibly
picking up an inch of snow overnight. Light showers will continue
Wednesday morning over central and southern WY, but should
diminish by noon. Most of western WY will be dry with only some
light showers closer to the divide. Temperatures will near
seasonal with warming and clearing from the north during the
afternoon. High pressure then sets in from Wednesday night through
Friday, with strong surface inversions likely forming to keep
colder air in the valleys and basins.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Lipson
SHORT TERM...McDonald
LONG TERM...Hulme
AVIATION...Hulme
FIRE WEATHER...McDonald