Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/24/24
Area Forecast Discussion
National Weather Service Denver/Boulder CO
805 PM MST Sat Nov 23 2024
.KEY MESSAGES...
- Mountain snow and light low-elevation snow late Sunday and Sunday
night.
- Heavier mountain snow late Monday night through Wednesday night with
widespread and significant travel impacts likely.
- Increasing potential for snow across the lower elevations Tuesday
night and Wednesday.
- Chilly but mostly dry Thanksgiving Day.
&&
.UPDATE...
Issued at 801 PM MST Sat Nov 23 2024
Moisture will move into the nrn mtns late tonight with snow
chances confined to zn 31 towards morning. Otherwise, only
minor adjustments made to temps and winds overnight.
&&
.SHORT TERM /Through Sunday/...
Issued at 146 PM MST Sat Nov 23 2024
Current observations across METARs display afternoon temperatures
on track to reach above normal temperatures through the early
evening hours across the region. Gusty southwest winds produce
wind gusts up 35 mph continue over the higher terrain this
evening due to an upper level jet. Cross sections display incoming
upper level moisture tonight thus partly cloud skies are expected
for most the of the lower elevations and foothills. Additionally,
tonight`s temperatures slightly above normal as the plains reach
25-36F and mountains reach 14-27F.
Our upper level pattern quickly changes by Sunday afternoon as a
shortwave trough brings Pacific moisture through northwest flow.
Orographic flow should lead to 2-5 inches mainly for areas above 9
thousand feet north of the I-70 corridor. A few mountain valleys in
Jackson and Grand counties could also receive 1-2 inches of snow
through Sunday. There is potential for the incoming cold front to
arrive late Sunday afternoon shifting surface winds northwest. With
mid to upper level cloud cover increasing by Sunday afternoon, it is
possible a few areas across the plains may struggle to reach the mid
50s. Thus, this update includes a decrease in afternoon highs across
the eastern plains. A few areas along the I-25 corridor will be able
to peak through the cloud cover but expect upper 40s to mid 50s for
the lower elevations. High temperatures for the high country reach
the low 30s to low 40s.
&&
.LONG TERM /Sunday night through Saturday/...
Issued at 146 PM MST Sat Nov 23 2024
Widespread snow is expected in the mountains Sunday evening as
the tail end of an upper level trough and left exit region provide
lift. Cross sections show saturated air up to roughly 450mb.
However, lapse rates will only be 5-7 C/km and mountain top winds
end up being relatively weak (less than 20 knots). Add this up and
the orographic lift component of this system is weak. Going
snowfall forecast of 2-6 inches and up to 3 inches in the valleys
looks on track.
For areas east of the mountains...the foothills, urban corridor
and plains, there seems to be decent model agreement between the
GFS and ECMWF models and their ensembles with a period of light
snowfall Sunday night. However, the NAM/RAP/HRRR models don`t have
a clue. NAM cross sections for Sunday night show barely enough
moisture for clouds, let alone snowfall. The NAM/RAP/HRRR keep
primarily northwest (downslope) winds for most of Sunday night.
With surface high pressure building in from the north, we should
see a period of northeast to east winds as the GFS and ECMWF are
advertising. These east to northeast winds lead to convergence
along the foothills and upslope flow. Temperatures appear cold
enough for all snow, though can`t rule out a little rain at first.
Plan to nudge snowfall amounts up, especially on the west side of
the urban corridor, in and near the foothills. Snowfall amounts
still look to be on the light side, less than 2 inches, but a
better chance for slick roads for the Monday morning commute
across western portions of the metro area. It quickly clears
Monday morning as upper level ridging and subsidence moves
bringing mostly sunny skies. Temperatures will be a little cool
with highs in the mid to upper 40s across northeast Colorado.
For Monday night through Wednesday night, westerly flow aloft
will transport Pacific moisture across the intermountain west
resulting in snowfall for the Colorado mountains. For the first
part of the storm, orographic lift will produce most of the
snowfall across the mountains through late Tuesday. Then an upper
level trough moves into the region providing lifting across the
mountains and also for the lower elevations Tuesday night through
Wednesday night. Still plenty of model differences out there
regarding this storm. The latest models move up the timing of the
trough passage. The GFS and its ensemble members are on the lower
end for snowfall with less than a foot of snow for the mountains.
The ECMWF and Canadian ensemble members favor 1-2 feet of snow for
the mountains. Will trend the forecast towards the heavier
amounts given the amount of moisture being transported into the
region and the duration of snowfall being 48-72 hours for the
mountains. For the lower elevations east of mountains, the upper
level trough should bring a decent shot of snow late Tuesday
through Wednesday night. Amounts are still quite unclear this far
out, but it`s very likely we will see snow covered roads Wednesday
and Wednesday night, leading up to Thanksgiving.
For Thanksgiving, the upper level trough and snowfall associated
with it shifts southeast of the area, with only a few ensemble
members hanging onto snow in the morning. However, even though the
snow is expected to be finished, roads will likely be slippery
Thanksgiving morning. Northwest flow aloft will prevail behind the
exiting system Thanksgiving. This combined with fresh snow
covered will produce cool temperatures with highs in the 30s
across northeast Colorado.
For Friday and next weekend, a longwave trough will reside over
northeast North America with a high over low set up along the west
coast of North America. This pattern will bring northwest flow
aloft to Colorado resulting in cool and dry conditions.
Temperatures are expected to be below normal with highs in the 30s
to lower 40s during this period.
&&
.AVIATION /00Z TAFS through 00Z Monday/...
Issued at 436 PM MST Sat Nov 23 2024
Winds will gradually shift to the south by 01z and then more SSW
by 05z. On Sun winds will become SW by 13z. Meanwhile, confidence
in wind direction by midday is low at best. HRRR has winds
becoming gusty from the west while other models have a Denver
Cyclone SW of DIA which leads to a more E or NE direction in the
aftn. For now have maintained continuty with previous fcst and
kept them from the west thru 22z. After 22z the winds may swicth
to a more NW component. Meanwhile VFR conditions will continue
tonight thru Sun aftn.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 AM Sunday to 6 AM MST Monday for
COZ031.
&&
$$
UPDATE...RPK
SHORT TERM...AD
LONG TERM...Meier
AVIATION...RPK
Area Forecast Discussion
National Weather Service Cheyenne WY
640 PM MST Sat Nov 23 2024
.KEY MESSAGES...
- Elevated to critical fire weather conditions and strong gusty
winds will continue for portions of Carbon, Albany, and
Converse counties through the early evening hours.
- A storm system will bring colder temperatures and a chance for
snow showers Sunday and Sunday night. Light accumulations are
expected for the I-80 corridor west of Cheyenne. Winter
Weather Advisories have been issued for the mountains.
- Another round of snow showers and colder temperatures may
impact holiday travel on Tuesday into Wednesday.
&&
.UPDATE...
Issued at 631 PM MST Sat Nov 23 2024
Strong winds with gusts over 40 MPH continue for the Arlington/Elk
Mountain area this evening. Downsloping winds in this zone are
also keeping relative humidity at critical thresholds, despite
the sun going down. Observations from this zone show wind gusts
between 35 and 45 MPH with relative humidity values below 15
percent. Due to the persistent critical fire weather conditions,
did decide to extend the Red Flag Warning for the Arlington zone
until 9 PM. Hopefully by then, humidity will recover above
critical thresholds with lighter winds. However, will re-
evaluate before the Red Flag Warning expires as the HRRR
continues to show relative humidity below 15 percent through
about midnight.
&&
.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 200 PM MST Sat Nov 23 2024
A Pacific jet streaming across the Western CONUS this afternoon is
producing plenty of mid to high level cloud cover over the area
visible on the latest satellite imagery. While a low amplitude but
fairly strong ridge is still holding on across the area, this will
break down over the next 24 hours as the messy trough over the
Pacific Northwest moves eastward. Currently, two distinct air
masses are positioned over the area: a warm and remarkably dry
airmass covering most of the area, while a surface high to the
northeast is keeping cooler and more moist air in place mainly
along/north of the North Platte River Valley. The boundary layer
is extremely dry for this time of year southwest of the
boundary, producing fairly widespread critical fire weather
conditions when factoring in the gusty southwest winds.
Additionally, gradients are strong enough to produce a few gusts
in the 55-60 MPH in Carbon County. As we head into the evening
hours, the surface high over western Colorado is expected to
weaken, reducing the cross-barrier MSLP gradient and allowing
high winds to die down. High Wind Warnings and Red Flag Warnings
should be able to expire on time at 6PM, but RH will probably
remain near critical to critical for a few hours after.
Heading into tonight, an approaching shortwave riding along the jet
stream will nudge into the area. Mid-level moisture will rapidly
recover this evening, allowing orographic snow showers to return to
the mountains after midnight. The boundary layer will still be
extremely dry in the valleys, so it may take a few hours to moisten
up the lower levels and allow snow showers to spread to the lower
elevations. This should happen quickly after the shortwave trough
axis and associated frontal boundary arrives, which is expected
to be around 12z near Rawlins and Douglas. Expect rapid low-
level moistening after this, which will then quickly increase
snow shower coverage, driven primarily by frontogenesis. The
cool-down and wind shift will happen fairly quickly over the
High Plains, but the mid- level boundary and associated lift
will be slower to clear out, not finishing up until a secondary
trough axis/vorticity maximum clears the area Sunday evening. As
a result, snow showers are expected to increase in coverage
over the High Plains Sunday late morning into the afternoon, but
downslope flow along/south of the North Platte River valley
will undercut the lift. Accumulating snow is likely to be
focused further north, in the Pine Ridge and vicinity where up
to 1-2" will be possible. Further south, expectations are for
just a few snowflakes to a half inch or so on the high end.
Modest impacts are also likely for the I-80 corridor from the
summit westward, where a general 1/2-3" can be expected. There
is about a 20% chance of a higher end scenario which would
warrant a Winter Weather Advisory for the Rawlins to Arlington
corridor, but confidence is too low to issue any products at
this time. As usual, the highest amounts will be in the
mountains where low end advisory amounts of about 4-9" are
expected. Therefore, a Winter Weather Advisory has been issued
for the higher mountains in the Sierra Madre and Snowy range.
Once the secondary trough axis clears the area Sunday evening,
expect a quick end to precipitation as much drier air moves in along
a subtle ridge axis. Expect cooler temperatures Monday, but the
quick rebound of the ridge should lead to highs ending up just a few
degrees cooler than average.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 200 PM MST Sat Nov 23 2024
Fairly zonal flow aloft expected for Tuesday ahead of an incoming
shortwave trough from the northwest. Significant jet energy is
expected Tuesday as the upper-level, 160kt jet moves overhead.
Westerly flow remains throughout the atmosphere, leading to a 40kt
jet across the Laramie Range Tuesday morning. Elevated winds will be
likely along and just east of the Laramie Range along the I-25
corridor. High Winds are currently not expected, as the 700mb trough
is not quite strong enough and in-house random forest guidance does
not favor high winds for Tuesday. Rising motion associated with the
upper-level jet combined with westerly to southwesterly 700mb and
surface winds favor the development of upslope flow and moderate
snow across the Sierra Madre Range, with the Snowies being mostly
shadowed due to the wind direction. Near-average precipitable water
values will favor continued development of snow showers across the
higher terrain. The Sierra Madre Range could see over a foot of snow
Tuesday morning through Wednesday evening. However, there is some
disagreement between long range models of how much QPF will be
available across the mountains. The ECMWF favors much higher QPF
throughout the duration, while the GFS keeps slightly lower values.
These differences result from the displacement of the surface low
between models. the GFS keeps the low further south, while the ECMWF
keeps it further north. The further north track is more favorable
for heavier precipitation, due to wrap around moisture, while the
southern path keeps much of the better moisture out of the region.
An attendant cold front associated with the incoming upper-level
trough will push through late Tuesday night into early Wednesday
morning. Cold temperatures will pour into the region behind this
front, with the upper-level trough quickly moving overhead. Long
range models have come into better across on the progression of the
cold front, with both the ECMWF and GFS pushing the front through by
early Wednesday morning. Northerly flow will develop behind the
passing front, though winds are expected to remain relatively light.
The warmest temperatures on Wednesday are expected around midnight,
with temperatures dropping steadily into the 20s and 30s area-wide.
Overnight lows will drops into the teens and low-20s Wednesday night
into Thursday morning. With the upper-level trough pushing through,
rising motion will be present across the region, leading to the
threat of isolated to scattered snow showers. The higher terrain is
expected to continue to see snow throughout the day Wednesday, with
lower-lying areas seeing the potential for snow throughout the day.
Accumulations are not expected to be much across the region, outside
of the mountains, due to the relatively warm conditions in the days
leading up to this event. Any snow that falls will likely melt, due
to the warmer ground conditions.
The remaining forecast period remains unsettled, as primarily
northwesterly flow remains aloft. Snow chances for the lower-terrain
taper off by Thursday morning, but snow chances in the Sierra Madre
and Snowy ranges continue through the period. With northwesterly
flow aloft, winds are expected to remain elevated, especially across
the wind prone regions of southeast Wyoming. Temperatures remain in
the 30s and 40s as northwesterly flow acts to keep temperatures
cooler by bringing in cooler Canadian air into the region.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 444 PM MST Sat Nov 23 2024
An incoming system overnight will increase clouds and precipitation
chances over the area. A cold front will move from west to east over
the forecast area tonight and through the day Sunday. KRWL will be
the first terminal affected with low stratus and scattered snow
showers forecast late tonight and early Sunday morning. Expect IFR
conditions from both poor visibility in falling snow and low CIGs.
Next precipitation and low CIGs will spread into KLAR by Sunday
morning. Terminals east of the Laramie Range will see precipitation
and low CIGs later in the day on Sunday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 9 PM MST this evening for WYZ427.
Winter Weather Advisory from 3 AM Sunday to midnight MST
Sunday night for WYZ112-114.
NE...None.
&&
$$
UPDATE...SF
SHORT TERM...MN
LONG TERM...AM
AVIATION...SF
Area Forecast Discussion
National Weather Service Quad Cities IA IL
549 PM CST Sat Nov 23 2024
.KEY MESSAGES...
- Highs Sunday 8 to 13 degrees above normal. Near normal Monday,
then below normal into late week.
- One or more systems will be moving through the Midwest during
the holiday period (mid week into next weekend). Considerable
uncertainty exists regarding the track and potential for any
impacts to the area.
- The pattern change that occurred last week will remain active
through early December. Temperatures will likely (70-90%) be
below normal into early December. There is no clear signal
that favors above, below, or near normal precipitation, which
would more likely be snow with colder temps.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 315 PM CST Sat Nov 23 2024
Tonight, light southeast winds and high level clouds will be
seen as high pressure drifts east and a low pressure system
approaches from the central plains. Some fog is possible along
highway 20 mainly mid to late evening into the overnight but
confidence is low with light southeast winds increasing enough.
Opted not to include in grids. Lows will be nearly steady in
the mid and upper 30s.
Sunday, the plains low will track over the area. This will usher
in seasonable mild temperatures into the area on southwest
winds. The gustier winds will be across the southern CWA late
morning and early afternoon. As the warm front lifts through,
can`t rule out some sprinkles early and then light rain/drizzle.
Added some low POPS for light rain generally along and east of
the MS River for after sunset into early Monday. Only expect a
trace to a few hundredths at best of rain. Highs Sunday were
nudged down a bit, but still look on track to be in the upper
40s to near 50 north, to the upper 50s to near 60 south. Normals
are in the low to mid 40s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 315 PM CST Sat Nov 23 2024
Monday and Tuesday, a high pressure ridge will traverse the area
with mainly dry conditions. A cold front will be east of the
area early Monday with brisk NW winds increasing through the day
while ushering in much colder air. Temperatures won`t see much
improvement on Monday, with steady or slowly falling
readings in the mid 30s NW to low to mid 40s along and E of the
river. Some lingering slight chances for light rain are in the
NE Monday morning, and east for the afternoon.
Tuesday looks to be quiet and chilly with below normal highs
mostly in the 30s, as surface to mid level ridging dominates.
Winds will be light west northwest with sunshine giving way to
some increase in clouds.
The Thanksgiving Holiday time frame remains a focus and
potential time for precipitation, but there is still a lot of
uncertainty. Through collaboration, bumped up POPS for
Wednesday into Thanksgiving as some models hint at an fgen band
initially Tuesday night into Wednesday across the north. Then,
with a southern system tracking across MO which brings in
precip chances across the SE two thirds of the CWA. With
placement and timing differences, the end POPS are just slight
to low chance (20-30%) with diurnally-driven precip types, snow
versus rain. At this time, WPC has QPF focused south of the
area, with the CWA remaining dry. Will need to monitor this due
to the travel day and expect changes as we get closer.
Beyond, confidence remains high on turning much colder and well
below normal at the end of November and beginning of December.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 549 PM CST Sat Nov 23 2024
VFR conditions start off the TAF period, with BKN high cirrus
clouds overhead. The main focus for tonight continues to be on
fog potential for areas north of Highway 30, including the DBQ
TAF terminal. Latest models suggest a little later time frame
for fog development than previously expected, with the
possibility of some IFR visby reductions late tonight, so have
made adjustments to capture this. Additionally, strengthening
low-level flow aloft will support low-level wind shear at BRL,
which is indicated by both the NAM and RAP models. Otherwise,
expect southeasterly flow during the daylight hours Sunday,
with continued VFR clouds.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...14
LONG TERM...14
AVIATION...Schultz
Area Forecast Discussion
National Weather Service Goodland KS
425 PM MST Sat Nov 23 2024
.KEY MESSAGES...
- Patchy fog possible tonight-Sunday morning east of a line from
McCook to Hill City. Dense fog is possible.
- Precipitation chances (20%-40%) continue Tuesday night
through the day Thursday with the emphasis of better chances
Tuesday night and Wednesday for light rain showers and snow
showers.
- Above normal temperatures Sunday fall to below normal levels
Monday through Saturday.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 145 PM MST Sat Nov 23 2024
Tonight...the forecast area will be under west-southwest flow aloft
with cirrus clouds moving through. Low temperatures are forecast to
be in the upper 20s to middle 30s. RAP/HRRR/NAM visibility forecasts
are forecasting some fog across the eastern 1/4 or so of the area
after about midnight. Dense fog is possible.
Sunday-Sunday night...any morning fog across the eastern 1/4 or so
of the area in the morning is forecast to dissipate/move out of the
area by mid to late morning. Otherwise, an upper level trough passes
through the area late in the afternoon, pushing a cold front through
the area. No moisture to work with so we`ll continue with a dry
forecast during the day. Overnight, the moisture profile in the 850-
500mb layer does improve and for now we`ll keep silent pops going
generally north of Interstate 70. High temperatures are forecast to
range from the 40s in snow covered areas of Cheyenne/Kit Carson
counties in Colorado to the 50s and lower 60s elsewhere. Low
temperatures fall into the lower to middle 20s.
Monday-Monday night...although the upper trough axis moves away from
the area during the day, there is disagreement amongst the
NAM/GFS/ECMWF models on the 850-500mb moisture profile with the NAM
the driest amongst the three and the GFS/ECMWF models agreeing with
each other and the NBM current forecast. High temperatures fall back
into the lower to middle 40s with low temperatures in the lower to
middle 20s.
Tuesday-Tuesday night...zonal flow is established during the day,
ahead of an approaching open wave trough that reaches the northern
plains southwest into the Colorado high country. Favorable moisture
in the 850-500mb layer holds off until the overnight hours when 20%-
30% chances for light rain showers and snow showers reach parts of
far eastern Colorado. With NAM/GFS 850mb temperatures warming 9F to
11F compared to Monday, high temperatures in the lower to middle 50s
look good. Low temperatures are forecast to be in the 25 to 30
degree range.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Issued at 145 PM MST Sat Nov 23 2024
Wednesday...there is pretty good agreement between the
GFS/ECMWF/GEM/GEFS models in supporting 20%-40% chances for light
rain showers and snow showers during the day as the upper trough
moves through. These models also bring in a lot of dry air behind
the trough passage overnight, supporting a dry forecast. The NBM and
current forecast has 20%-40% chances for snow showers overnight.
We`ll watch upcoming model cycles and see if this trend continues or
follows the GFS/ECMWF/GEM/GEFS trends of a dry overnight period.
High temperatures are forecast to be in the lower to middle 40s with
low temperatures in the upper teens to lower 20s.
Thursday...the forecast area is forecast to be under northwest flow
aloft. The current forecast has a 20% chance for light snow showers
in the morning along and north of Interstate 70 but given the
GFS/ECMWF/GEM 850-500mb relative humidity forecasts of rather dry
air, I`m doubtful we`ll get any precipitation for the entire day.
High temperatures will be rather chilly in the middle 30s to lower
40s. Low temperatures are forecast to be in the teens.
Friday...we remain under northwest flow aloft. Presently, the
forecast remains dry as the better 850-500mb moisture needed for
precipitation remains to the northeast and east of the area. High
temperatures are similar to Thursday in the middle 30s to middle 40s
with low temperatures in the middle teens to lower 20s.
Saturday...not much change in the 500mb pattern nor at the surface
with dry weather forecast and high temperatures in the middle 30s to
middle 40s and low temperatures in the 10F to 15F range.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 425 PM MST Sat Nov 23 2024
GLD: VFR conditions will rule through the TAF period, with
ceilings confined to cirrus at or above ~20,000 ft AGL. Light
(5-10 knot) southeasterly or variable winds will prevail through
sunrise Sunday. Winds will shift to the N or NNE and modestly
increase to ~8-14 knots late Sunday morning (~17Z) and persist
through the afternoon. Northerly winds will further increase to
15-25 knots around sunset Sunday evening (~00Z Mon) -- in
assoc/w rapid surface pressure rises -- as Canadian high
pressure (centered over southern Alberta) builds/extends
southward along the lee of the northern and central Rockies.
MCK: Fog may develop over portions of south-central Nebraska
and central Kansas early Sunday morning (~07-14Z Sun). While fog
is possible at McCook.. visibility forecasts via recent runs of
the HRRR suggest that locations east of McCook are most at-risk
for early morning fog. Otherwise, VFR conditions will rule
through the TAF period with ceilings confined to cirrus at or
above ~20,000 ft AGL. Light (4-8 knot) southeasterly or variable
winds will prevail through sunrise Sunday. Winds will shift to
the N or NNE and modestly increase to ~8-14 knots late Sunday
morning (~17Z) and persist through the afternoon. Northerly
winds will further increase to 15-25 knots around sunset Sunday
evening (~00Z Mon) -- in assoc/w rapid surface pressure rises --
as Canadian high pressure (centered over southern Alberta)
builds/extends southward along the lee of the northern and
central Rockies.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...99
LONG TERM...99
AVIATION...Vincent
Area Forecast Discussion
National Weather Service Green Bay WI
500 PM CST Sat Nov 23 2024
Updated aviation portion for 00Z TAF issuance
.KEY MESSAGES...
- The chances for light rain and snow from Sunday night through
Monday night have increased. There is a 40-50% chance of getting
at least 1 inch of snow in north-central WI, and a 30% chance
to get at least 2 inches of snow.
- Light lake effect snow at times over far north-central Wisconsin
mid to late next week. Only minor accumulations are expected.
- A cooling trend takes hold for the coming week. Highs in the 30s
and 40s into Monday will cool into the 20s to 30s by the middle
of the week, and into the 20s across the entire area by next
weekend.
&&
.DISCUSSION...
Issued at 320 PM CST Sat Nov 23 2024
Short Term...Tonight and Sunday
Main focus for the remainder of today is cloud trends. Current
satellite imagery shows partial clearing across northern WI, while the
rest of the region remains under a blanket of mid-level clouds.
These clouds are streaming in in advance of an upper trough that is
forecast to arrive to the region tomorrow. Radar has picked up a few
weak echos early this afternoon across central WI as weak
frontogenesis is driving areas of virga. However, area web-cams have
shown no signs of any precipitation reaching the region.
A weak ridge sliding over the region overnight will keep the dry
conditions around through Sunday morning. Warm air advection ahead
of the aforementioned upper trough may produce scatter areas of
drizzle beginning Sunday afternoon, however, forecast soundings are
split as to if any precipitation will make it to the ground. NAM
soundings continue to be the most aggressive with sufficient
saturation taking place during the afternoon to get areas of
drizzle, while RAP soundings are slower to saturate resulting in a
later onset of any precipitation. Regardless do not expect any
impacts through Sunday afternoon. Precipitation chances do increase
Sunday evening as does the chance for accumulating across northern
WI.
Long Term...Sunday Night Through Saturday
A surface low moving from Missouri to Lake Huron will bring some light
rain and snow to the region Sunday night through Monday evening. Most
of it will fall as rain Sunday night, but the rain should change to
snow across north central Wisconsin Monday before it diminishes Monday
evening. An inch or two looks likely there with not much elsewhere.
Winter will finally begin to arrive during the middle of next week,
as the medium range models show an upper ridge begin to build along
the west coast, and a trough over central Canada and the Great Lakes
region. Temperatures are forecast to be below normal by the end of
next week, with subzero wind chills possible Friday and Saturday night.
A surface low moving from Oklahoma to the Ohio Valley looks like
it could bring some light snow to southern Wisconsin Wednesday
night, but otherwise the northwest upper flow will result in dry
weather Wednesday through Saturday outside of some light lake
effect snow in Vilas county.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 500 PM CST Sat Nov 23 2024
High and mid clouds are expected across the area tonight as they
stream in from the west. Some MVFR stratus will be possible this
evening across the far north with northwesterly flow. VFR
conditions will continue into Sunday with thickening and lowering
clouds throughout the afternoon. Lower CIGs and precipitation is
expected to hold off until Sunday evening as a surface trough
tracks through the area. Light surface winds below 10 knots are
expected during the TAF period.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....GK/RDM
AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service North Platte NE
542 PM CST Sat Nov 23 2024
.KEY MESSAGES...
- Patchy fog development tonight into Sunday morning across southwest
into south central Nebraska with visibilities of < 1 mile
possible at times.
- A cold front moving in Sunday will bring much cooler
temperatures, breezy winds, and a threat for light snow (<
1") across portions of northwest Nebraska.
- Benign weather Monday and Tuesday before an even colder
airmass settles into the central US by the middle to end of
next week. A threat for wintry precipitation exists,
potentially impacting Thanksgiving holiday travel, however,
uncertainties remain in regards to snow accumulations.
&&
.SYNOPSIS...
Issued at 244 PM CST Sat Nov 23 2024
Recent GOES-16 WV imagery and RAP 500-mb analysis showed a broad
ridge extending across the central CONUS. An upper-level low was
centered over the north Atlantic, tracking northeast into Canadian
Maritimes. Just to the east of this feature, an upper-level trough
was sliding southeast across northern Ontario. A robust upper-level
low pressure system continues spinning off the coast of British
Columbia with a trough extending southwest into the eastern Pacific.
Multiple shortwaves and vorticity lobes were ejecting inland within
the southwest flow aloft over the Pacific Northwest and northern
Rockies. At the surface, a weak back-door cold front was draped
across western and central Nebraska. Widespread cirrus clouds
continue to move into the area with a stratus deck noted over
portions of northern Nebraska. Given the cloud cover, temperatures
have trended cooler than previously expected, especially for
northern Nebraska, with 2 PM CT temperatures ranging from 30 degrees
at Valentine to 54 degrees at Imperial.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 244 PM CST Sat Nov 23 2024
A potent upper-level shortwave will eject from the main system
centered off the coast of the Pacific Northwest into the northern
Rockies late tonight. As this shortwave moves eastward into the
northern Plains, a cold front will be forced southward, moving
through the area late tonight into Sunday morning. Ahead of the
front, patchy fog development appears increasingly possible
across portions of southwest and south central Nebraska
resulting in visibilities falling to 1 mile or less at times.
Although high clouds may pose a less favorable environment, it
appears breaks in the clouds and light winds may be just enough
to allow fog to development. Visibility may change rapidly
while driving, so Sunday morning travelers over the
aforementioned areas should stay alert. As the front clears the
forecast area Sunday morning, northwest/north winds will
strengthen behind it with 3 to 4mb/3 hour pressure rises and
cold air advection (CAA) increasing across western and north
central Nebraska. Widespread gusts in excess of 20 mph will be
common during the day on Sunday with the strongest gusts of 30
to 35 mph expected across northern Nebraska. As for Sunday`s
highs, temperatures will range from the upper-30s behind the
front across northern Nebraska to the mid-50s ahead of the front
across southwest Nebraska. This frontal passage will bring the
first of a series of cold air intrusions expected through the
week with Sunday night`s temperatures falling near 10 degrees
across northwest Nebraska to near 20 degrees across southwest
Nebraska. With breezy northwest winds gusting up to 25 mph
through the night, we will see some chilly wind chills falling
into the single digits by Monday morning. The cold overnight
temperatures, increased moisture and mid-level forcing will
present a threat for light snow/flurries across northwest
Nebraska Sunday night, potentially extending east into north
central Nebraska. Little to no accumulation is expected with
current NBM Probabilities of 24 Hour Snowfall > 1" remaining at
20% or less for northwest Nebraska. At this time, any winter
weather impacts appear low, though this will lead to much colder
temperatures as we head into Monday.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 244 PM CST Sat Nov 23 2024
As the flow aloft becomes zonal and surface high pressure builds
southward out of Canada, quiet conditions will settle into the area
Monday and Tuesday. With CAA continuing across the region,
temperatures will fall into the 30s to low-40s on Monday. Although
temperatures moderate back into the 40s as the upper-level ridge
flattens over the northern Plains on Tuesday, an even colder airmass
settles into the region for Wednesday and beyond.
The main focus in the long term revolves around the next system
ejecting out of the Rockies mid-week, potentially impacting
Thanksgiving holiday travel across our area. This mid-week threat
for snow remains low confidence as the deterministic ECMWF, GFS, and
Canadian continue to have run-to-run differences on the evolutions
of this system. As a heavily tilted upper-level trough extending
from the northern Rockies into northern California advances eastward
into the Plains through Wednesday, a lee-cyclone will develop across
southeast Colorado driven by mid-level height falls and upper-level
divergence. The main surface low will track southeast into the
Oklahoma/Texas Panhandles, remaining well south of the area.
Despite this, a cold frontal passage will bring increased mid-
level forcing, resulting in a threat for light snow across
western and north central Nebraska. Although discrepancies
exist amongst deterministic guidance, 50% or more of the GFS and
ECMWF ensemble members highlight the potential for light snow,
perhaps accumulating snow. Although uncertainties remain, with
such cold air in place, the threat for accumulating snow is non-
zero across the area with NBM Probabilities continuing to
highlight a 15% chance or less of 1"+ of snow. Thanksgiving
travelers should continue to stay up to date on the latest
forecast and be prepared to make adjustments to your plans if
needed, especially those who may be headed to Colorado where the
greater potential for winter impacts exists.
The one thing that appears more certain with this system is the
northern Plains seeing the most significant cold air outbreak
of the season thus far. Ensemble guidance shows a ridge
developing over Alaska and northern Pacific, favoring surface
high pressure to build southward into the central CONUS by late
next weekend, continuing into the 7 to 10 day range. Just how
cold it will get remains uncertain at this time, however,
confidence continues to increase in a period of sub-freezing
and perhaps well-below freezing temperatures to be felt across
the region as we head into the first part of December. This is
highlighted by CPC`s 6-10 Day Temperature Outlook favoring
below normal temperatures across the eastern third of the CONUS.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 541 PM CST Sat Nov 23 2024
For the KLBF terminal: Lower clouds will move into the area
overnight with ceilings around 2500 FT AGL. There is also a
threat for patchy fog at the terminal with visibilities as low
as 2sm during the overnight hours. Skies will scatter out on
Sunday with scattered ceilings around 20000 FT AGL. For the KVTN
terminal: Expect ceilings below 1000 FT AGL through 08z
overnight. Skies will remain cloudy, however, ceilings will
increase to around 12000 FT AGL as winds shift to the west then
northwest overnight. Lower ceilings will then set back in by mid
to late morning Sunday with cloud decks around 2000 FT AGL.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...Buttler
Area Forecast Discussion
National Weather Service Marquette MI
704 PM EST Sat Nov 23 2024
.KEY MESSAGES...
- Active weather with periodic chances for accumulating snow return
next week. Temperatures will begin to trend below normal for this
time of year.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 218 PM EST Sat Nov 23 2024
Water vapor imagery and RAP analysis show a low amplitude mid-level
ridge across the central U.S. and a mid-level low over the NE U.S.
To the n, another mid-level low is centered in nw Ontario. A
shortwave extends from that low into northern and eastern Lake
Superior. KMQT radar and visible satellite show nw flow lake effect
rain and snow showers across much of the fcst area. Latest RAP
analysis indicates temps at the base of inversion at 850-800mb are
at -7C to -9C, marginal for the ongoing light lake effect pcpn. The
aforementioned shortwave could be providing weak enhancement to the
lake effect showers.
With caa lowering 850mb temps down to -8 to -10C through this
evening, expect nw flow lake effect pcpn to continue, especially
east where the colder 850 mb temps will be and where the longer
fetch will be across northern and eastern Lake Superior. However,
with inversions heights only at 4-5kft, and even a little lower over
the western fcst area, expect any lake effect pcpn to be light
through this evening. Ridging building in from the west, especially
late tonight, should taper or end lake effect showers for all areas
except maybe the far eastern cwa. Min temps tonight under partly to
mostly cloudy skies will be generally in the mid to upper 20s inland
to around 30F near the Lake Superior shore.
&&
.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 443 PM EST Sat Nov 23 2024
Starting Sunday, a mid level ridge moves east into the Great Lakes.
That said, the cloud cover is still expected during the day with
troughing building in from the west. Highs on Sunday are forecasted
in the mid 30s to low 40s.
The dry period then ends Sunday night into Monday as a clipper low
approaches from the Canadian Provinces, phasing with a Colorado low
that lifts into the Great Lakes on Monday. Isentropic ascent looks
to kick off some showers Sunday night from the south, which expand
northeast across the UP through Monday as the features phase
together and the mid level trough begins swinging through the
region. Where there still is some uncertainty in the forecast is the
sfc low track. The NAM and much of the high resolution model
guidance are in "camp one" where the Colorado low takes a more
northerly track over southeastern WI and over northern/central Lower
MI. This track which would bring a warmer airmass to our CWA and
start precip earlier in the CWA. This solution also would imply a
brief period where a wintry mix of rain/snow/sleet, most likely in
the interior central UP (near Iron Mountain). Some freezing rain is
also possible Sunday night over that region with a marginal warm
nose above 5kft. Ice accumulations would likely be sparse at best,
around a trace early Sunday night. Otherwise, snow is expected north
and west of the wintry mix area and mainly rain showers with some
snow mixing in later in the day near Lake MI. "Camp two", being the
rest of the guidance such as the GFS and ECMWF, take the sfc low
over southern Lower MI. This would result in less wintry mix, which
would be mostly rain and snow) and more snow overall in the CWA with
a cooler airmass overhead. Either solution looks to result in some
light snow accumulations over the north half of the UP and possibly
some slippery road conditions going into Monday.
Monday night through Tuesday, the mid level trough pivots over the
Upper Great Lakes. This is the beginning of troughing period over the
Great Lakes, yielding cold northwest to north flow that is expected
the rest of the extended forecast. 850 mb temps diminish from around
-7C Monday night to around -13C by the end of next week, sufficient
for LES (especially with Lake Superior being warmer than normal for
this time of year with average sfc temps ~8C). Several inches of
snow are likely over the course of next week, especially over the
east where some pre treatment from Lake Nipigon is expected.
Currently, Wednesday and Thursday look to bring the least amount of
precip with weak sfc ridging passing through briefly. Temps trend
toward below normal for Thanksgiving weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 703 PM EST Sat Nov 23 2024
Persistent MVFR cigs will continue at IWD and CMX through the night
as low level moisture remains trapped under an inversion. Some
fluctuation to VFR at SAW is occurring, but expect MVFR to be
predominant at SAW as well through the night. No wind impacts,
light and variable.
&&
.MARINE...
Issued at 443 PM EST Sat Nov 23 2024
Northwest winds of 20-25 kts over the east half of the lake this
afternoon diminish this evening, falling below 20 kts across the
lake. Winds veer northeast for Sunday then east Sunday night as
broad ridging moves through the Upper Great Lakes. While a few gusts
up to 20 kts are possible over the western third of the lake late
Sunday (~20% chance), winds are expected to hold mainly below 20 kts
until Monday night when a Colorado low moves through the Great
Lakes. This Colorado low phases with another low approaching from
the Canadian Provinces on Monday resulting in an uptick in northwest
winds of 20-25 kts Monday night through Tuesday. Strongest winds up
to 30 kt are possible on Tuesday, mainly over the waters south of
the Keweenaw (~50% chance). Winds then weaken to 20 kts or less
again Tuesday evening as the now phased low pulls away towards the
Atlantic. With weak impulses from the north moving through the area
much of next week, expect the light northwest to north winds mainly
less than 20 kts to continue until late next week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...Jablonski
AVIATION...TDUD
MARINE...Jablonski