Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/09/24
Area Forecast Discussion
National Weather Service Denver/Boulder CO
828 PM MST Fri Nov 8 2024
.KEY MESSAGES...
- An ongoing winter storm is generating heavy snowfall across much
of northeast and north central Colorado through Saturday
morning. Heavy snow will fall from the eastern foothills west of
Denver/Boulder, south and east to the east central Plains.
- Very difficult and hazardous winter driving conditions are
expected for much of northeast and north central Colorado,
including the Urban Corridor.
- Warmer and drier weather returns on Sunday with a chance of snow
returning to the high country on Tuesday. Windy Front Range
Mountains and foothills Saturday night/Sunday morning and again
Tuesday night into Wednesday.
&&
.UPDATE...
Issued at 825 PM MST Fri Nov 8 2024
Water vapor shows the upper level low over sern CO near the Kansas
border. The low is fcst to move almost due north with it over
swrn NE by 18z on Sat. QG analysis shows favorable ascent
overnight but decreasing by 12z. KFTG VWP shows winds are trending
to the NNE along the Urban Corridor. Radar loops continue to show
a concentrated band of moderate snow with some heavier snow along
and east of I-25 from the WY border southward to the Palmer
Divide. This activity appears to be getting locked in place with
lighter snowfall in and near the foothills. Meanwhile, across the
rest of the plains, activity continues to redevelop to the north
and west of the main low. Overall, the fcst for tonight, looks to
be mainly on track, although amounts in and near the foothills may
end up on the lower range of forecasted snow amounts.
On Sat, a deformation zone will be in place on the backside of the
upper level low as it moves into swrn NE by midday. Thus, there
will likely be additional heavier snowfall lingering thru midday, to
the west of the main upper level low. Not exactly sure where it will
set up, but this could bring warning type amounts to portions of
Morgan and nern Weld counties before it decreases. Meanwhile, the HRRR
has this additional snowfall somewhat further west affecting
portions of the Denver metro area. Overall confidence in placement
of this activity is rather low, so will leave current highlights
as is.
&&
.SHORT TERM /Through Saturday/...
Issued at 156 PM MST Fri Nov 8 2024
GOES-16 water vapor shows an impressive storm system with a warm
conveyor belt advecting moisture all the way from Texas, wrapping
it around the center of the vorticity max into northeast
Colorado. The trough will lift north-northeast from it`s current
position over the OK Panhandle into eastern Nebraska by Saturday
evening. From this evening into the late morning hours tomorrow,
there are impressive sources of lift associated with the northwest
quadrant of the trough. First, strong QG lift will be in place
through late morning, but strongest this evening. Also maximized
this evening will be jet-induced lift, with strong diffluence
associated with a southeast to northwest-oriented 80 kt jet on
the east side of the trough. Deep upslope flow is in place with 20
kts out of the east from now through this evening. Winds at 700
turn to the NW overnight, and are fully and strongly northwest by
12Z. With the trough lifting into Nebraska, and winds going
northwest at 700, we feel snow rates will come down significantly
after midnight. However, snow won`t shut off entirely because
there is still a lot of lift associated with the TROWAL. That
seems to be the main forcing to keep snow going until late morning
across the area, but additional accumulations in the late morning
hours should be very light.
With the lifting trough to the north, snow should end first
across the hardest hit areas of Elbert and Lincoln Counties,
perhaps as soon as sunrise but for sure the snow should be light
in the early pre-dawn hours. Snow should end around midday across
the I-25 corridor and foothills to the east. There may be a few
instability snow or rain/snow mix showers Saturday afternoon in
the wake of the lifting trough, mainly north a Boulder to Fort
Morgan line. Accumulation from those showers will be minimal as
temperatures will be above freezing by then. The last place to see
a shutoff of the precip will be the northeast corner of colorado
near and northeast of Sterling. Lingering rain showers may go
until early afternoon before shutting off. It should be all rain
east of Sterling for this event. Temperatures on Saturday will
struggle to reach the 40s in most areas of the plains, though Fort
Collins eastward to Greeley and the northeast corner of Colorado
should reach the mid 40s. Elsewhere right around 40 deg is
expected.
In terms of amounts, 3-4 day totals exceeding 3 feet are likely
across eastern Elbert and Lincoln Counties. It may take a while to
clear all the roads just based on the heavy snow. Some blowing
and drifting snow is possible across east central Colorado but
mainly overnight with gusts 20-30 mph. Winds weaken out there by
Saturday afternoon which is good. Across the Palmer Divide,
another 7-14" is expected through tomorrow for totals over 2`.
The eastern foothills west of Denver/Boulder, and the metro
Denver/Boulder areas are slated for 5-14" through tomorrow.
Further north, temperatures are warmer and snowfall rates will be
a bit less, so advisories look okay for now with 2-6" possible
along and north of US-34. As before, there will be a tight
gradient in snow along the northern end. In terms of impacts: The
PM commute for pretty much everywhere south of US-34 is going to
be messy with heavy snow and accumulating snow/ice on the
roadways. Slow down, expect travel delays, and leave plenty of
room between you and the person in front of you.
The last thing to mention, which we haven`t even mentioned yet,
are the mountains and west slope. Light snow is expected across
the mountains and mountain valleys this evening and overnight.
Minor travel issues are expected across the main mountain travel
arteries west of the Divide. However, snowfall will pick up
Saturday afternoon as moist, west upslope flow returns when the
trough reaches central Nebraska. 1-5" with isolated higher
amounts should fall across the northern mountains through the
evening hours.
&&
.LONG TERM /Saturday night through Friday/...
Issued at 156 PM MST Fri Nov 8 2024
Saturday night the large upper low that brought all the snow to
eastern Colorado will have moved into the Upper Midwest with drier
conditions across the CWA. There may be just enough lingering
moisture to produce a few light snow showers over the high country,
mainly over the higher peaks. Cross sections are showing a mountain
wave setting up with wind gusts to 60 mph over the Front Range
Mountains and foothills late Saturday night into Sunday morning.
Warmer and drier weather is expected Sunday and Monday as upper
level high pressure builds over the state.
By Tuesday, we start seeing some differences between the models. The
GFS is showing a weak upper trough moving across the Northern and
Central Rockies, while the majority of the models have a deeper
trough moving across the forecast area. The GFS solution lacks
moisture and would result in little to no precipitation across the
mountains. On the other hand, some of the other models have more
moisture and quite a bit of QG lift which lends to a better chance
for snowfall across the high country with scattered showers possible
across the plains. At this time, will go with the NBM model blend
which seems like a reasonable compromise. We also could see
another mountain wave forming along the lee of the Rockies Tuesday
night into Wednesday with windy conditions across the higher
Front Range Mountains and foothills. This pattern could also
produce breezy conditions across portions of the plains as well.
Dry weather and above normal temperatures are expected for Thursday
and Friday as upper level high pressure builds over the Rocky
Mountain Region.
&&
.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 422 PM MST Fri Nov 8 2024
Periods of mdt to heavy snow will continue thru late evening with
LIFR ceilings and visbility. By 08z, will continue to see lighter
snow which will continue thru 16z Sat. Snow should end between 18z
and 20z on Sat. Ceilings will remain LIFR thru 18z but should
gradually lift by 20z. Visbility will be IFR thru 18z and then
rise above 6sm by 20z. Winds will be N to NNW tonight through 16z
Sat and then more NW after 16Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MST Saturday for COZ033>035-
038-042>044.
Winter Storm Warning until noon MST Saturday for COZ036-039>041-
045-049.
Winter Weather Advisory until 5 AM MST Saturday for COZ037.
Winter Storm Warning until 5 AM MST Saturday for COZ046-047.
&&
$$
UPDATE...RPK
SHORT TERM...Schlatter
LONG TERM...JK
AVIATION...RPK
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
950 PM CST Fri Nov 8 2024
...New AVIATION...
.UPDATE...
Issued at 700 PM CST Fri Nov 8 2024
Some showers have developed along the cold front as it moves across
the US 77 corridor. There remains a potential for storms in that
area through around 9 PM CST, however the chances are very low since
the front has been undercutting their development. Behind the front,
showers continued to move east over the far eastern Hill Country
into the I-35 corridor. These will continue to move east and exit our
area overnight. Strong to severe storms are no longer expected with
the airmass stabilizing after sunset and frontal passage along with
the better thermodynamics well off to our northeast. Have re-
established trends to the sensible weather for tonight based on
recent observations.
&&
.SHORT TERM...
(Tonight through Saturday night)
Issued at 244 PM CST Fri Nov 8 2024
Early afternoon radar imagery shows a solid line of showers and
thunderstorms stretching from near Pearsall northward into the Hill
Country to Fredericksburg and Llano. This line of convection is
associated with a cold front, with temperatures behind the front in
the mid 50s to mid 60s, with lower 70s to mid 80s ahead of the
boundary. Elsewhere, some light shower activity is noted farther
east from portions of the coastal plains northward to just east of
the Highway 77 corridor. The last few runs of the HRRR model seem to
latch on to the current radar trends and do show the cold front and
line of showers and storms continuing to move eastward this
afternoon and evening. However, as the line moves toward the I-35
corridor, it is expected to break up into clusters of showers and
storms instead of a solid line. We could still see a strong to
possibly severe storm or two and the Storm Prediction Center
maintains a Marginal Risk (level 1 of 5) for areas generally along
and north of a Llano to Hondo to La Grange line. As the front moves
into the Highway 77 corridor and encounters some deeper moisture,
there is a little better chance for showers and storms over Lee,
Bastrop and Fayette counties during the early evening hours. Rain
chances will be on the decrease after Midnight and should mostly be
confined to areas along and east of Highway 77. Some cool and dry
air pushes in behind the front with overnight lows expected to drop
as low as the lower 40s across portions of the southern Edwards
Plateau into the western Hill Country where skies will be mostly
clear. Farther east, clouds look to linger, but we should still see
lows dip into the mid 50s to lower 60s along and east of I-35.
Clouds should thin as the day progresses on Saturday with daytime
highs in the lower 70s to near 80 for most locations.
&&
.LONG TERM...
(Sunday through Friday)
Issued at 244 PM CST Fri Nov 8 2024
The upper level flow will become zonal at the start of the long term
period. Dry weather will settle in for upcoming week. Models show
almost no chance for rain with the highest POP in the long term in
the single digits. Along with the rain free forecast we can also
expect a warming trend for the start of the period. High temperatures
Sunday will be around five degrees higher than Saturday and Sunday
will be another couple of degrees higher. Temperatures should remain
nearly steady Tuesday and Wednesday. Highs will be mainly in the 80s
which is well above normal and close to records in some places.
Wednesday a cold front will move through our CWA. While it won`t
bring any rain, it will bring cooler air. This will be especially
noticeable Thursday morning when lows will be around 10 degrees
cooler than Wednesday.
&&
.AVIATION...
(06Z TAFS)
Issued at 950 PM CST Fri Nov 8 2024
VFR flying conditions prevail overnight through Saturday night with
CIGs AOA FL035. At the I-35 sites, N-NE winds 8 to 14 KTs decrease
to 5 to 10 KTs on Saturday, then less than 5 KTs Saturday night. At
KDRT, northwesterly winds around 5 KTs shift to southeasterly
Saturday afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 58 77 57 82 / 30 0 0 0
Austin Bergstrom Intl Airport 58 76 57 81 / 30 0 0 0
New Braunfels Muni Airport 61 80 59 85 / 20 0 0 0
Burnet Muni Airport 52 74 55 79 / 20 0 0 0
Del Rio Intl Airport 52 77 56 83 / 0 0 0 0
Georgetown Muni Airport 54 74 55 80 / 30 0 0 0
Hondo Muni Airport 57 78 57 83 / 10 0 0 0
San Marcos Muni Airport 58 77 57 83 / 30 0 0 0
La Grange - Fayette Regional 59 76 60 81 / 40 0 10 0
San Antonio Intl Airport 61 79 60 83 / 20 0 0 0
Stinson Muni Airport 63 81 62 85 / 20 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...04
Long-Term...05
Aviation...04
Area Forecast Discussion
National Weather Service Marquette MI
544 PM EST Fri Nov 8 2024
.KEY MESSAGES...
- Dry weather through Saturday with above normal temperatures, then
rain returns Saturday night and Sunday.
- Blustery west to northwest winds on Monday, especially over
the Keweenaw and eastern Lake Superior shoreline areas where
gusts of 40-45 mph are possible.
- Next chance for widespread precipitation possible
Wednesday/Thursday, but uncertainty on specifics remains high.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 242 PM EST Fri Nov 8 2024
Water vapor imagery and RAP analysis show mid-level ridging over the
Northern Rockies into Alberta/Saskatchewan/Manitoba with downstream
trof over se Canada and the ne U.S. A cutoff low is centered over
NM. At the sfc, upstream ridge is supporting building high pres over
the Upper Mississippi Valley. After rapid development of stratocu
this morning, mainly across n central and eastern Upper MI, incoming
dry air mass has eroded much of those clouds this aftn. However, air
mass is cold enough over eastern Lake Superior (850mb temp around
-4C per latest RAP analysis) for some lake stratocu to develop
over the lake and stream into eastern Upper MI. Current temps are in
the mid 40s to lwr 50s, but as high as the mid 50s F far s central.
So, about 5-10 degrees above normal for this time of year.
With sfc high pres ridge moving across the fcst area during the
evening, the evening will be quiet with winds diminishing to
calm/near calm. Sct-bkn stratocu will continue to stream into the
eastern fcst area this evening until arrival/passage of high pres.
Otherwise, clear skies will prevail tonight. Expect min temps from
the low/mid 20s in the interior, coldest e, to the low/mid 30s F
along portions of the Great Lakes.
&&
.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 433 PM EST Fri Nov 8 2024
The dry pattern will persist through Saturday under the influence of
surface and upper-level ridging. At that point though, focus quickly
shifts to a closed low approaching from the Central Plains. This
will be Upper Michigan`s next chance for rain through Sunday. Some
inconsistency, however, still remains between the ECMWF and GFS in
regard to track and timing of the surface low with the GFS taking a
slightly faster and more northern route through northern Wisconsin
on Sunday. Meanwhile, the ECMWF leans toward a more southern route
across southern Wisconsin. This difference in path may only mean
the difference between a tenth or two-tenths of an inch of rain,
though, with the 75th-25th percentile still trending in the 0.1 to
0.2 inch range.
By Sunday night, any lingering rain showers will become confined to
the eastern portions of the U.P. with little to no measureable
rainfall as brief ridging strengthens over the area. The lull in
activity will be short-lived, though, as a Clipper system dips down
from Ontario with an associated cold front and wind shift to the
west-northwest on Monday. An abrupt drop in 850 mb temperatures over
relatively warm water will be conducive to lake effect rain/snow
showers, especially across the east sector of the forecast area.
But, main impacts will be the strong west-northwest winds progged to
gust up to 40-45 mph over the Keweenaw and eastern shorelines. As
subsidence strengthens with ridging late Monday, any lingering lake
effect precipitation will taper off, and a dry period will ensue
through Tuesday.
After the break, yet another frontal system moves through the region
around mid-week with the GFS/GEFS once again trending toward a
faster track than the EMMWF/EPS. As a result, will not deviate much
from the model blend at this time. But, best precip chances are
leaning somewhere between the Wed 18Z-Thu 06Z time frame. Ptype
will generally be in the form of rain, but as overnight lows in the
20s become more predominant over the second half of the extended
period, chances for rain/snow mix become more probable over the cold
prone areas of the interior west. Meanwhile, daytime highs late in
the period will generally hover around the low to mid 40s. Until
then, upper 40s/low 50s will be predominant from Saturday through
Wednesday.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 544 PM EST Fri Nov 8 2024
VFR conditions will continue through the forecast period at all
sites.
&&
.MARINE...
Issued at 453 PM EST Fri Nov 8 2024
As surface high pressure strengthens from the west this evening, any
lingering 20+ kt gusts over eastern Lake Superior will also subside
with the entire lake under less than 20 kts into tonight.
As high pressure moves east of the Upper Great Lakes and a surface
low approaches from the Central Plains on Saturday, winds will
become southwesterly and increase to 20-25 kts (highest north-
central and east). After a lull from Saturday night through Sunday,
an uptick in west-southwest winds will return Sunday night with
gusts as high as 25-30 kts, eventually shifting to the west-
northwest and increasing further behind a cold front early Monday
morning. By mid-morning Monday, west-northwest gales of 35 to 40
kts are expected to develop (mainly central and eastern Lake
Superior).
Northwest winds will shift to the north-northeast and fall below 20
kts by Monday night as a high briefly overspreads the area. However,
they will once again ramp up to 25 to 30 kts out of the southeast
Tuesday afternoon and approach low-end gale criteria again by
Tuesday night/Wednesday over northern and eastern portions of the
lake as yet another frontal system enters the region.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...TDUD
AVIATION...07
MARINE...TDUD