Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/05/24
Area Forecast Discussion
National Weather Service La Crosse WI
550 PM CST Thu Jan 4 2024
.KEY MESSAGES...
- Occasional light snow chances (20-60%) this weekend with the
highest odds of light accumulations (at least 1") across
north-central WI.
- A larger, more impactful winter storm will impact portions of
the Mississippi Valley later Monday and Tuesday. Current
forecasts keep the greatest impacts south from the Mid-MS
Valley into the Great Lakes, but some uncertainty in track
persists. If you have travel plans across the Midwest early
next week, continue to monitor forecasts.
- An active weather pattern may hold through next week with increasing
chances for colder air by later next week.
&&
.DISCUSSION...
Issued at 234 PM CST Thu Jan 4 2024
Tonight-Friday:
Despite surface ridging working across the area today, shallow
moisture/stratus beneath an inversion has had a tough time eroding
given limited mixing/heating. At this point, confidence in
widespread clearing is relatively low, and additional mid/high
clouds will begin to spread back across the area later tonight
and Friday atop the lower stratus. The RAP tries to show
deepening low-level saturation (up to 1-1.2 km) tonight with
continued warm advection. With the lack of any more prominent
shortwave troughs to assist with lift, confidence of any
freezing drizzle/flurries for southeast MN/northeast IA is quite
low (<10%) at this time. The cloud/moisture trends will need to
be monitored this evening, though. Otherwise, some flurries
could not be ruled out into Friday as broad lift gradually
increases ahead of a progressive mid-level trough.
Saturday-Sunday: Periodic light snow
A messy flow is expected through the weekend with broad mid-level
troughing and a few weaker waves passing through the area. Lift does
not look overly strong, but each wave could generate some light snow
at times. Although precipitation amounts will be light, the raw
suite of global ensembles indicate periods of higher chances (40-
80%) north of I-94 Friday night and 20-50% Saturday night into
Sunday. Although there are some timing/placement issues with any of
the light precipitation, chances may need to be bumped up from NBM
with time as confidence in details tightens. The greatest chance for
any accumulations occurs Friday night across north-central WI with
odds of 1" of snow 30-60% across northern parts of Clark and Taylor
Counties.
Monday-Thursday: Early Week Winter Storm Potential
The focus heading into next week remains on the potential for a
winter storm to impact portions of the Midwest early in the week.
Overall, model guidance remains steadfast in showing a strong
Pacific trough ejecting from the southern plains Monday into the Mid-
MS Valley by late Tuesday. With the split flow pattern in place, a
main source of uncertainty is with the northern extent of
precip/exact track of the cyclone. With this general consensus
track, the higher odds (>50%) for at least 3" of snow from Missouri
northeast through Illinois and lower Michigan with lower chances (10-
20%) extending into southwest Wisconsin. However, there still is a
subset of global ensemble members (~30%) that are somewhat stronger
and farther north with the snow band into southwest WI and northeast
IA. Either way, some light snow would be possible locally. The key
takeaway remains that while current trends favor the highest impacts
to the south, some adjustments in track are expected over the next
few days, which will affect the magnitude of impacts locally.
Beyond this system, an active period may continue well into next
week with ensembles favoring continued troughing over the
center of the nation. Spread is quite large by mid to late week,
but there are also signals for an intrusion of colder air to
spread southeast out of Canada later next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 544 PM CST Thu Jan 4 2024
Widespread MVFR stratus extends from eastern Wisconsin through
the local forecast area into western and north-central
Minnesota. Therefore, MVFR expected for 05.00-24Z TAF. High
resolution model guidance has been all over the place so have
used specific grids for population instead of a model consensus.
May see ceilings lift VFR through 05.18Z however low confidence
and have not included in TAF at this time. Will lift from
southeast to northwest if they do.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...JM
AVIATION...JAR
Area Forecast Discussion
National Weather Service Cheyenne WY
743 PM MST Thu Jan 4 2024
.KEY MESSAGES...
- An active weather pattern continues into next week with colder
temperatures, regular chances for mountain snow, and
occasional light snow in the lower elevations.
&&
.UPDATE...
Issued at 735 PM MST Thu Jan 4 2024
Forecast remains largely on track. Freezing fog has developed
near Sidney this evening. Expanded fog potential further north
towards Box Butte County as conditions will be favorable for fog
overnight. At this time, decided against any fog headlines due
to limited expanse and duration, but may need a Freezing Fog
Advisory for Cheyenne County later this evening. Overcast skies
currently over most locations, so increased overnight lows a
degree or two as clouds will act to keep locations slightly
warmer.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 218 PM MST Thu Jan 4 2024
Still some persistent fog hanging around in the southern Nebraska
panhandle this afternoon. Expired the Freezing Fog Advisory earlier,
as fog should gradually lift throughout the day. Low stratus will
likely linger longer and become more widespread, potentially into
Carbon and Albany Counties tonight as more moisture from the storm
system to the south is pushed into the CWA. Could see some light
flurries or snow showers develop tonight along the Interstate-80
corridor with the best chances for snow being in the mountains and
in Cheyenne County per Hi-Res guidance. Upper-level support for this
system looks poor, with little lift and forcing, therefore not
looking at much in terms of snow accumulation overnight. Some
areas could see a dusting.
Heading into Friday and Saturday, several embedded shortwaves will
traverse the area. The first will pass through during the day on
Friday, increasing precipitation chances across the CWA. Did raise
PoPs a bit compared to the previous forecast package now that Hi-Res
guidance is starting to capture this weak system. There is a bit
better support aloft with better lift and some frontogenetical
forcing too. This could support a few light to moderate snow bands
developing during the afternoon and evening. Overall, coverage of
snow showers will be widely scattered, with the best chances for
precipitation being in southeast Wyoming. Snow totals for the plains
should remain under an inch. The Snowy and Sierra Madre Range, and
even the far north Laramie Range could pick up a quick 2 to 6 inches
between Friday and Saturday.
The secondary shortwave on Saturday looks relatively dry. Some
lingering snow showers possible in the mountains, but overall, this
shortwave will dry out the lower levels. This second shortwave will
also bring in cooler air, with highs on Saturday in the 20s and 30s,
which is actually below average for this time of year.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 218 PM MST Thu Jan 4 2024
Focus of the long term forecast continues to be monitoring for the
potential for a a major storm system to approach the Front Range
region Sunday into Monday. For much of next, and after this
potential storm system, persistent cold northwesterly flow and weak
shortwaves will bring cold temperatures and the threat of daily snow
flurries and/or snow showers to most valleys and some light
accumulating snowfall to the mountains.
There will be a brief lull in the snow/flurry activity on Saturday
as a quick moving, sharp ridge axis moves aloft. There will be
enough moisture embedded underneath this ridge to keep skies cloudy
which will help in keeping overnight low temperatures from dropping
too much, but there is high confidence that much of the region will
see overnight lows in the teens.
The next impactful weather we are tracking is a deep trough emerging
across the Intermountain West. Some slight changes of note to
discuss regarding the model outputs in terms of evolution and track
of this incoming storm system. The current ECMWF run overall has
transitioned from an open wave to a large closed low system over the
Four Corners and pushing this system SE across northern New Mexico
and into the Texas Panhandle. Some ensemble members have gravitated
toward this scenario as well recently. This change is also 12hrs
sooner from when the GFS develops a closed low system. This new
output does put our region in a somewhat better regime dynamically
for more snowfall across the region but the track is still
unfavorable for high impact snowfall.
The GFS latest model and ensemble outputs have remained fairly
similar but the location of the closed low has shifted north a bit
from the previous run. While this northerly track does put some of
the better QPF fields across SE Wyoming underneath a weak upslope
flow, the location of the low and track are unfavorable for more
significant snow, but if this track continues to push north and the
GFS closes the low off sooner, this could put us in play for a more
high impact snow event Sunday through Monday. This is something we
will watch in the coming days and make the necessary adjustments if
we get better model consistency.
Beyond Monday confidence remains that our region may see a slight
warmup as we also see a return of some strong winds as models are
advertising a retreating jet stream to the north and help initiate
some of those stronger winds. Confidence for high winds is low at
this time but after a lull in the winds lately it will be something
that we will be watching. Heading toward the middle of next week,
models are showing a strong storm system entering the Pacific
northwest with a very strong cold front ushering in some very cold
air. Ahead of this storm system, moist westerly flow should be
adequate enough to initiate some persistent mountain upslope
snows.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 424 PM MST Thu Jan 4 2024
Low stratus and fog continues in the eastern Panhandle around
KSNY and KAIA this evening. Using latest HRRR guidance...looks
like the IFR conditions will continues at these two airports
through the evening hours. May see some up valley starts at KBFF
later this evening as winds turn up valley from the southeast.
To the west...look for lowering conditions at KRWL and KLAR
towards 12Z as light snow begins to move into the area.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...AM
SHORT TERM...SF
LONG TERM...AW
AVIATION...GCC
Area Forecast Discussion
National Weather Service Dodge City KS
535 PM CST Thu Jan 4 2024
...Updated Aviation Discussion...
.KEY MESSAGES...
- Moderate to occasionally heavy snow approaching far southwest
Kansas this evening. Light-moderate snow much of the night
into early Friday leading to minor travel impacts.
- Most areas 1 to 3" total snowfall with Storm #2. Elkhart area
and also the Red Hills region have been bumped up to 3-5"
total snowfall forecast.
- Break in between storm system Late Friday through Sunday.
- High-impact winter storm is still on track to affect much of
Kansas, including southwest Kansas. Increasing confidence in
moderate snow accumulations in excess of 3 inches and very
strong north winds leading to increased concerns for
significant blowing and drifting snow.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 342 PM CST Thu Jan 4 2024
Snow will overspread southwest, west central, and eventually south
central Kansas this evening through the first half of Friday. This
is Storm #1 of 2 (Storm #2 will be discussed in the Long Term
section). For incoming Storm #1, impacts are expected to remain
minor with this storm, however some locally, brief moderate impacts
with completely snow-packed roads cannot be ruled out as some areas
will likely see brief 1/2" to potentially 1" per hour snowfall rates.
Now that the storm is on approach to Southwest Kansas, short term
high-resolution models generally have a pretty good handle and the
HRRR is very good guidance for timing, intensity, and location of
heavier snow. The first of two heavier axes of snow was already
underway across the western Texas Panhandle with heavy snow reported
at both Clayton, NM and Dalhart, TX at 2030Z (230 PM CST). This
will continued its push northward toward Elkhart, which is the
first location to see snow with this storm by sunset. This axis of
snow will remain well-organized with up to 1" per hour snowfall
rates lasting an hour or two for a quick couple inches of snow. As
this axis continues northeast through the late evening, around 1/2"
per hour snowfall rates will push up toward Garden City-Dodge City.
After midnight, this first axis of snow is likely to weaken with
lower snowfall rates, which is why total snowfall amounts for this
storm will continue to be lower the farther north toward I-70
corridor (generally 1 to 2" snowfall total).
Overnight after midnight, another organized axis of moderate to
briefly heavy snow will develop just north of the upper low itself
as it makes its closest approach to southwest Kansas (between 09-15Z
Friday). This second heavier snowfall axis is forecast to extend
from the central/eastern Oklahoma Panhandle northeast across Meade-
Greensburg-Coldwater-Pratt-Medicine Lodge areas. We have increased
the snowfall forecast for these areas focused on/around the Red
Hills region where we are now going for 3-5" in addition to the 3-5"
total for the Elkhart area. Temperatures will likely be 31-33F for
nearly the entire event, including overnight tonight, and this will
help keep road surface temperatures from falling much below 32F, if
at all, so road pre-treatments will likely have a very effective
positive impact on ground travel across southwest Kansas. This is
the reason why impacts are expected to remain minor, despite 2-4"
forecast. Nevertheless, there will also likely be a 1-3 hour period
when snowfall rates will be high enough to promote at least some
slushy accumulation on treated and/or heavily traveled road
surfaces. The last of the two snow axes will move east out of south
central Kansas (particularly Red Hills) by around midday Friday.
After the snow ends, Friday afternoon will likely remain cloudy as
HREF low level cloud probabilities remain 80-100% all the way
through sunset Friday early evening.
Clouds will be slow to erode Friday Night, and this should help keep
temperatures from bottoming out much below the 25 to 30F range for
lows early Saturday morning. On Saturday, a northwest wind 12-18 mph
will develop in the wake of Storm #1 with some remnant clouds
hanging around. Snow melt will likely be fairly slow given early
January low sun angle and temperatures likely not exceeding much
above 40 degrees for afternoon highs.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 342 PM CST Thu Jan 4 2024
The focus for this Long Term discussion will continue to be Storm #2
and its potential moderate to major impacts to our region. The
Weather Prediction Center`s Winter Storm Severity Index defines
major impacts as considerable disruptions to daily life including
dangerous or impossible driving conditions or widespread
closures/disruptions to infrastructure. As has been mentioned in
previous discussions regarding Storm #2 (Monday-Monday Night),
intense north winds along with moderate to heavy snow remains a real
concern. This storm still appears to be a fairly far-reaching storm
insofar as that much of Kansas will likely to be affected in some
way (minor, moderate, and/or major impacts). The latest 100-member
Super Ensemble (today`s 12Z run) is showing 50th percentile 3-5"
from Dodge City northeastward toward Salina. A reasonable upper-
bound range (1-in-4 chance) on the latest Super Ensemble for much of
southwest Kansas (including Liberal, Dodge City, Scott City, Hays,
and Pratt is 5-7" for Storm #2. Since Storm #2 is now in the 96-120
hour range, global deterministic models are expected to become
increasingly stable in terms of forecast storm track, intensity, and
timing, such that we will begin to feel more confident in some of
the finer details, including how strong peak wind gusts may be,
timing of arrival of strongest north winds, duration of heaviest
precipitation rates and how that would time out with strongest
winds, and of course, when the storm will end with improving
conditions.
The latest NBM has 75th percentile 24-hr peak wind gusts
with this storm in the 45-55 mph range, and should the reasonable
upper-bound wind gusts pair up with reasonable upper-bound total
snowfall, blizzard or near-blizzard conditions can be expected. One
positive note about Storm #2 is that it will be moving east at a
fairly decent speed, since this storm is not expected to completely
"cut off" from the main polar jet stream and anchor over our region.
All of the ensemble guidance shows the surface low moving across
Oklahoma fairly quickly over 12-18 hours, so duration of 25-35 mph
sustained north winds will likely not last more than 12 to 18 hours
late Monday/Monday Night. Winds are currently expected to decrease
substantially Tuesday, such that any Moderate/Major impacts should
not linger long in the day Tuesday.
We still expect some fluctuations in the storm track, intensity, and
timing, which will result in a change in our current forecast of
winter impacts for Southwest Kansas in particular. For that reason,
please stay up to date with the latest information concerning this
winter storm system Monday and Monday Night.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 518 PM CST Thu Jan 4 2024
23z radar from KDDC and surface observations indicated
precipitation was already moving into portions of southwest
Kansas with the CAMS in decent agreement with this area of
steadier precipitation spreading from the Liberal area at 00z
Friday into the Garden City and Dodge City area between 02z and
04z Friday. Initially this precipitation will begin as a wintry
mixing of rain and snow but within 1 to 2 hours will transition
over to all snow. As the snow develops ceilings will fall to
less than 500ft AGL with the prevailing visibilities being
reduced to 2 miles or less due to snow and fog (>80%). These
low ceilings will linger through Friday afternoon while the low
visibilities will begin to improving between 12z and 15z Friday
as the snow begins to taper off from west to east. Hays will be
far enough north where they will observer the snow and low
visibilities occurring after 06z with the best chance for the
steadier and heavier snowfall occurring (40-50%) between 11Z and
15z Friday.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Friday for KSZ030-031-
044>046-064>066-077>081-087>090.
Winter Weather Advisory until 9 AM CST /8 AM MST/ Friday for
KSZ043-061>063-074>076-084>086.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
547 PM CST Thu Jan 4 2024
...New AVIATION...
.SHORT TERM...
(Tonight through Friday night)
Issued at 135 PM CST Thu Jan 4 2024
Synopsis: Early afternoon RAP analysis indicates a weak closed low
over NM and a sfc trough not far away from it. As the upper low
spins ENE to the southern Plains and opens by Friday morning, a sfc
low will continue to develop that will trek across the Panhandle. In
turn, this will drag a Pacific cold front across our region during
the early daylight hours. Showers will develop in a region of
isentropic ascent tonight ahead of this system, but will quickly
clear out behind the front as some drier air filters in.
Details: Dew points have increased some today thanks to ESE to SE
flow in the area. Most locations except for portions of the Coastal
Plains are socked in under cloud cover, and so temperatures remain
mired in the upper 40s in portions of the Hill Country and Southern
Edwards Plateau. Meanwhile, a few southern/eastern locations are in
the low 60s this afternoon.
Isentropic lift (or upglide, or ascent, or whatever term you prefer)
will strengthen late this afternoon into the evening over primarily
central and eastern portions of the region. The end result is that
showers will increase in coverage through the evening, then shift
east of the US-281 corridor before sunrise and exit our eastern
counties likely well before noon. Patchy to areas of fog are also
forecast. Clear skies will follow behind the front, so highs will
actually be significantly warmer in some areas on Friday. Most
locations will be in the 60s, with a few southern/western locations
reaching the low 70s.
Accumulating rains will be spotty west of US-281 and mainly non-
existent west of US-83. For the east half of the region, most
locations will likely only pick up 0.10-0.25" or so, but locally
higher totals to about 0.50" are possible. In our far southeastern
counties we couldn`t rule out an isolated 1" amount. Some thunder is
also possible in this region.
Breezy winds are forecast over some western locations tomorrow
midday through the afternoon, sustained at 15-20 mph with perhaps a
few 30 mph gusts. But they`ll quickly diminish Friday evening. This,
combined with clear skies, will make for a cool night with Saturday
morning lows in the 30s for most locations.
&&
.LONG TERM...
(Saturday through Thursday)
Issued at 135 PM CST Thu Jan 4 2024
Despite a shortwave moving through the southern Plains late
Saturday, dry conditions and seasonable temperatures are forecast
for this weekend. On Monday, a deep upper level low will make its
way into the region from the west with an associated surface low
moving through the area during the day. In the warm sector,
increasing chances for showers and storms can be expected with the
best chances for rain being across the eastern half of the area.
This system is forecast to be much more dynamic than recent systems
we`ve seen, with a favorable overlap of greater instability (60-80%
chance for CAPE >= 1000 J/kg according to the GEFS) and impressive
shear allowing for potential severe weather. As of now, these
ingredients are most likely to align across our far eastern counties
(continuing to the east as the system progresses that direction),
though there are still some slight differences in the
timing/placement of the upper low that could shift the area of
concern. We will continue to monitor this over the coming days, as
will SPC. If severe weather does materialize across portions of our
CWA, forecast soundings indicate a potential damaging wind and
tornado threat, with hail possible as well in any discrete cells
that manage to develop ahead of the main convective line.
Weather concerns continue behind the front Monday afternoon through
Tuesday as strong northwesterly winds develop in the wake of the
departing low, ushering in a dry airmass. The ECMWF Extreme Forecast
Index is hinting at an unusually strong wind event, especially across
the western half of the CWA, as sustained wind speeds of 20-30 mph
are looking likely with gusts as high as 40-50 mph. These winds will
coincide with minimum relative humidity values as low as the teens
(%) out west along the Rio Grande for Monday and Tuesday afternoons.
Near to above normal fuel moisture may preclude the need for
critical wording, but at least elevated to near critical fire
weather conditions are expected during these time periods.
Beyond Tuesday, a warming trend and dry conditions are in store as
flow aloft becomes zonal in between weather systems on the east and
west coasts.
&&
.AVIATION...
(00Z TAFS)
Issued at 521 PM CST Thu Jan 4 2024
Isentropic lift is now intensifying into this evening with an upper
level system advancing into Oklahoma and northern Texas. This will
result initially in drizzle across the I-35 TAF sites (KAUS, KSAT
and KSSF) before transitioning into scattered to widespread rain
later tonight and into the overnight hours. Additionally, ceilings
along with visibility are to reduce into the MVFR to IFR range. The
rain should shift east of the I-35 TAF sites by sunrise. However,
expect continued reductions in ceilings. The conditions may worsen
at KAUS around sunrise as the latest probabilistic guidance shows a
medium (30-50%) probability that ceilings and perhaps visibility
could lower into the LIFR range. Flight conditions will improve at
the I-35 TAF sites by around midday with clearing skies through
Friday afternoon with returning VFR conditions. Winds will mainly
remain light and variable tonight before increasing from out of the
west-northwest on Friday afternoon.
KDRT can expect majority of the rain and drizzle to remain east of
the site. However, expect for the IFR ceilings and visibility to
maintain into tonight. The latest short term guidance is now in
better agreement that conditions could deteriorate further towards
late overnight as an area of fog and very low ceilings develops
along the Rio Grande. This results in conditions to at least LIFR
levels. Probabilistic guidance does show a low to medium potential
of VLIFR levels for a time. Conditions gradually improve through
mid-morning before clearing out by afternoon at VFR levels. Winds
increase Friday afternoon with gusty northwesterly winds. Gusts up
to around 25 knots will be expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 46 64 39 63 / 80 0 0 0
Austin Bergstrom Intl Airport 46 66 36 63 / 80 10 0 0
New Braunfels Muni Airport 48 68 39 68 / 70 0 0 0
Burnet Muni Airport 45 63 36 60 / 80 0 0 0
Del Rio Intl Airport 42 70 37 70 / 0 0 0 0
Georgetown Muni Airport 46 63 36 61 / 80 0 0 0
Hondo Muni Airport 44 68 34 68 / 40 0 0 0
San Marcos Muni Airport 47 66 37 65 / 80 0 0 0
La Grange - Fayette Regional 50 63 39 61 / 80 30 0 0
San Antonio Intl Airport 48 68 38 67 / 60 0 0 0
Stinson Muni Airport 49 69 38 68 / 60 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...KCW
Long-Term...Gale
Aviation...Brady
Area Forecast Discussion
National Weather Service Green Bay WI
606 PM CST Thu Jan 4 2024
Updated aviation portion for 00Z TAF issuance
.KEY MESSAGES...
- The weather pattern will be conducive for several wintry systems
to impact the region over the next week.
- Probabilities for greater than 1 inch of snow have increased to
50-80% over far northern Wisconsin on Friday night into
Saturday. In general, a 1 to 3 inch snowfall is possible north
of a Wausau to Oconto line.
- A weather system could bring impactful snow Tuesday into
Wednesday, followed by another system Thursday and Friday.
There remains a great deal of uncertainty regarding the tracks
of each system, which will impact snow amounts.
&&
.DISCUSSION...
Issued at 231 PM CST Thu Jan 4 2024
Short Term...Tonight and Friday
The latest RAP analysis and satellite/radar imagery show a 1029mb
high pressure centered over the western Great Lakes. After some
breaks developed in the overcast early this morning, many of those
breaks filled back with the diurnal cycle. The downsloping area
over far northeast Wisconsin has seen some breaks redevelop and
clouds become more cellular. Widespread flurries were observed on
area radars into early this afternoon with some locally reduced
visibilities over Minnesota. Looking upstream, widespread overcast
prevails across the northern and central Plains. A weak, sheared
shortwave is moving across North Dakota with little consequence. A
more potent system is moving east across the southwest CONUS.
Forecast concerns mainly revolve around sky cover and temps,
followed by light snow chances on Friday afternoon.
Sky and Precip: As high pressure shifts from the western Great
Lakes to the mid-Atlantic states, light return flow will develop
across the region. Mid-level dry air will likely hold off any
significant precipitation chances until late Friday afternoon when
shortwave energy and low pressure move across the Plains. This
will lead to a low chance of light snow across far northern
Wisconsin generally after 3 pm Friday. Forecast soundings also
indicate saturation increasing from the ground up. For that
reason, will also add a slight chance of freezing drizzle to go
along with the snow.
Otherwise, scattered flurries will likely persist into the evening
if not longer over north-central Wisconsin.
Cloud cover remains difficult to forecast. But given the trends
and extensive cloud cover upstream, increased cloud cover to
broken or overcast for the duration of the short term period. Some
breaks in the overcast are possible at times, particularly over
far northeast Wisconsin where temps could fall quickly this
evening only to rise overnight as clouds return.
Temps: Readings underperformed today thanks to the cloud cover.
Trended warmer again tonight for min temps and not far from last
nights lows. Trended colder for highs on Friday as well.
Long Term...Friday Night Through Thursday
An active wintry weather patter is expected through the duration
of the extended forecast as a series of systems bring the
possibility of snow/precipitation.
Friday night through Sunday...Two successive surface lows and
coincident upper level short-waves are progged to pass over
western Great Lakes this weekend, bringing a chance (40-60%) of
snow. Higher snow totals are expected with the more northern
system passing over the area Friday night through Sunday morning
with a dusting to 3 inches of snow possible north of a Wausau to
Oconto line, highest amounts expected in northern Vilas County.
The more southern system passing over the region Saturday
afternoon into Sunday morning is not expected to have as strong of
ascent and a more shallow moisture layer which may limit snow
totals to under 1" across the Fox Valley and across east-central
WI.
Monday...A brief pattern of dry and overcast conditions are
expected Monday as a weak upper level ridge and surface high
pressure shift over the region.
Tuesday and Wednesday...There is still considerable uncertainty
regarding the potential for snow/precipitation with a systems
moving across the Midwest Tuesday and and Wednesday. Models
continue to consistently eject a strong well organized cyclone
out of the souther Rockies early next week that may impact the
eastern half of Wisconsin beginning Tuesday morning through
Wednesday afternoon. Ensemble mean tracks for this system
currently have the low center progged to track over southern
Illinois then toward southeast Michigan which would decrease the
likelihood of a significant wintry event across the GRB area with
the heaviest snowfall/precipitation further south toward
Milwaukee and Chicago metros. However, if the northern jet stream
over central Canada pulls this system further to the north areas
in the Fox Valley and across east-central and northeast WI may see
an increase in snowfall accumulations. Gusty winds associated
with a tightening pressure gradient are also possible with this
system.
Rest of the extended...The more active pattern pattern looks to
continue into the second half of next week ans model guidances
seems to be in decent agreement that another system could pass
through the western Great Lakes bringing another round of
accumulating snow. Given the timeframe uncertainty is high with
this system, but it is worth watching, especially for those
traveling during the second half of next week.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 605 PM CST Thu Jan 4 2024
Remained very pessimistic with the cloud cover tonight into
Friday with the strong inversion remaining in place. MVFR clouds
mainly between 2000-3000 ft will continue into the evening, likely
slowly lowering through the night. The small area of clearing
over far northeast WI should fill in this evening as the more
favorable downsloping wind shifts to the southwest. IFR CIGs are
possible on Friday, mainly over north central WI.
Flurries will also be possible at times tonight, especially across
northern WI. As moisture depth increases and we lose a little
mid-level moisture for a time, chances for some freezing drizzle
will arrive late tonight into Friday morning. Decided to include
at AUW/CWA/RHI. May need to add some lower VSBYs if the FZDZ
materializes. The FZDZ looks to change over to light snow over
central and northern WI on Friday, spreading into east central WI
Friday evening.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....MPC/GK
AVIATION.......Bersch
Area Forecast Discussion
National Weather Service Grand Rapids MI
1011 PM EST Thu Jan 4 2024
LATEST UPDATE...
Update
.UPDATE...
Issued at 1011 PM EST Thu Jan 4 2024
Only modification to the forecast this evening is to add a slight
chance of freezing drizzle for later tonight into Friday morning
where we currently have a chance of flurries (mainly western and
northern sections of the CWFA). Latest HRRR soundings are only
barely saturated at -10C when omega appears in the cloud deck late
tonight. Doubt we`d see much impact since any precip that breaks
out should be very light (if it even occurs), but it is something
to keep an eye on nevertheless.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 305 PM EST Thu Jan 4 2024
-- A Few flurries possible later tonight and Friday --
A few breaks in the clouds opened up away from Lake Michigan this
afternoon pretty much as expected. It was very evident that the
cloud layer was very thin, especially further away from the lake.
Weak upper short wave riding through the region tonight will help to
strengthen the low level flow from the SW, and help to replenish the
low level moisture under the inversion from Lake Michigan. In
addition, the dgz barely becoming saturated will allow for some
flurries to be possible for SW flow areas. The dgz being minimal,
over lake instability being barely enough, and the upper jet staying
north of the area will keep any flurries light.
The clouds and flurries will continue into Friday, with the low
level moisture maybe dissipating to the south with a southerly flow
developing. There may be a short period of clearing before mid and
high clouds move in ahead of the weekend system.
-- Next Chance for snow beginning late Friday Night --
Moisture will thicken up through Friday night as we see moisture
with the southern and northern systems stream in over the area. Most
of the night should be dry as it takes until almost 12z for
sufficient low level moisture to arrive just over the far southern
and southwestern portions of the area for precipitation to reach the
ground.
As has been expected all along, the precipitation should just about
be all snow. Even with warm advection trying to take place, colder
air from the northern stream will win out, and provide for an
atmosphere favored to support snow.
.LONG TERM...(Saturday through Thursday)
Issued at 305 PM EST Thu Jan 4 2024
-- Light accumulating snow Saturday and Saturday night --
We are looking at widespread accumulations on the order of an inch
spread out over this timeframe, with probable lesser amounts by the
lakeshore. The driver for the snow will be a clipper system with
attendant isentropic ascent dropping southeast across the region.
Lake enhanced snow and the back end of this system will be
negligible due to any marginally cold lower tropospheric
temperatures - i.e., centered around -8C at 850mb per the ensemble
guidance. Accumulations near the lakeshore should be especially
sparse to non-existent due to an unseasonably warm marine boundary
layer in the vicinity.
-- Increased chances for impactful mid-week winter storm --
Confidence is growing that there will be a winter storm either
directly impacting or in the vicinity of Lower Michigan. In fact,
ensemble guidance has begun to converge on a solution that, should
it occur, would be reminiscent of our recent December 22, 2022
blizzard. This would mean widespread snow accumulations well over 6
inches, followed by lake effect snow along with very strong
northwest winds that could produce blizzard-like conditions
Wednesday morning. However, precipitation type is far from certain;
a significant rain component remains possible and this could
significantly curtail snow accumulations.
While what`s described above is far from certain at this point, I
still feel it is worth mentioning now as a possibility for the
following reasons:
1) It is not too early to be thinking about contingency plans for
possible travel and power disruptions next week.
2) There has been a signal for a major pattern shift starting nearly
a week ago. This has consistently featured a deep, strongly phased
western U.S. trough resulting in surface cyclogenesis in the lee of
southern Rockies. These have a strong climatological propensity to
track northeast towards the Ohio Valley, often while deepening.
3) Past storms in recent memory exhibiting this pattern showed
remarkable predictability and consistency in model guidance leading
right up to the event. This presumably has much to do with inherent
predictability associated with deep longwave troughs such as the one
we`re dealing with now.
4) Ensemble solutions, particularly the ECWMF Ensemble (ECE),
indicate potential for explosive cyclogenesis as the surface low
tracks toward the Ohio Valley. The ECE mean MSLP has dropped to 980
mb, which would imply that several ensemble member solutions feature
minimum pressures significantly less than that. Not surprisingly, we
are now seeing Shift of Tails (SoT) values in the ECE approaching 2
or greater over parts of Lower Michigan. This means that there are
several ensemble member solutions behaving as extreme outliers
relative to ECE model climatology. This also emphasizes strong
positional sensitivity to the forecast when dealing with what could
be a very deep surface low setting up somewhere.
While it`s easy to focus on what snow occurs (which undoubtedly
could be especially jarring given the winter that we`ve had so far),
we are just as concerned about the wind threat that may manifest on
the back side of the exiting, deepening low. The official forecast
will continue to smear wind speeds downward due to averaging of
model solutions, but it should be noted that we could in fact
experience very significant northwest winds and gusts that may
impact much of Lower Michigan sometime in the middle of the coming
week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 706 PM EST Thu Jan 4 2024
Widespread MVFR cigs are expected tonight and Friday morning.
Currently it is still VFR east of GRR and AZO, but clouds will be
filling in and lowering there as well. The period of lowest
ceilings is expected to be between about 10Z and 16Z, especially
at MKG and GRR, when cigs could dip a bit below 2000 ft. Gradual
improvement to VFR is expected Friday afternoon from south to
north, with MKG probably the last to see cigs rise above 3000 ft.
&&
.MARINE...
Issued at 305 PM EST Thu Jan 4 2024
It is possible that we may not need marine headlines until next week
with the Tue/Wed storm. Winds and resulting waves look to stay under
criteria through the weekend until about Tue/Tue night. We do see
winds and waves increase a little ahead of and behind the weekend
system. The increase looks to be negligible at this time.
Gales do look likely with the Tue/Wed system, especially on the
backside with the colder air flooding in. Plenty of time to fine
tune those details being many days out.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...Meade
SHORT TERM...NJJ
LONG TERM...TJT
AVIATION...Meade
MARINE...NJJ
Area Forecast Discussion
National Weather Service North Platte NE
617 PM CST Thu Jan 4 2024
.KEY MESSAGES...
- Areas of fog, freezing drizzle and light snow continue tonight
through Friday night. Snow accumulations of an inch or less
are predicted and a Winter Weather Advisory is in effect
tonight for areas along and south of Interstate 80.
- Significant snow is expected Sunday night into Monday
affecting parts of ncntl Nebraska, generally along and east of
highway 183.
- The coldest air of the season will move into wrn and ncntl
Nebraska next week- Wednesday night. Highs and teens and 20s
are in place for next Thursday.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 310 PM CST Thu Jan 4 2024
The fog has been very slow to lift across swrn Nebraska today. This
is likely the result of strong moisture advection advertised by the
models. h850-300mb RH will increase to 80-90 percent tonight and the
model consensus shows the fog lifting; perhaps too quickly. It
appears the short term model blend can`t predict the advection fog
underway. The Dense Fog advisory has been extended to 00z this
evening and given the very strong 850-700mb moisture advection
tonight, there is a chance it will need to be extended into the
evening or perhaps even expanded in coverage.
The mention of freezing drizzle continues overnight and this is
based on NDOT cameras, ice accumulators on the sfc observations and
the KLNX radar which is beginning to show returns close to the
site; indicative of drizzle.
The snow forecast tonight and Friday morning continues on-track and
the models have increased the QPF amounts slightly. The models are
extending the event throughout the day Friday and overnight. Snow
amounts remain an inch or less in most areas but the expanse of
measureable snow includes much of wrn and ncntl Nebraska. The
forcing for this event is strong warm air advection (WAA) and the
approach of a Pacific cold front Friday night. It`s worth noting
winds will be weakly directionally sheared for a few hours tonight,
and this might support the development of a MCV driven snow
circulation. The predictability of this is low.
The continued WAA Friday afternoon and overnight ahead of the
Pacific front supports chance POPs across ncntl Nebraska. There is
also a snow chance in place across nwrn Nebraska behind the front.
This would be snow showers associated with cold air moving in aloft,
and moisture convergence around the Black Hills.
The temperature forecast tonight through Friday night leans heavily
on the short term model blend which captures the very limited
diurnal temperature range suggested by the RAP model, and the
consensus of the deterministic models.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 310 PM CST Thu Jan 4 2024
The latest guidance from WPC suggests 3 to 5 inches of snow
across ncntl Nebraska Sunday night and Monday, generally along
and east of highway 183. It`s uncertain if this snow emanating
from an upper level low circulating across KS will reach this
far north and west but the 12z NAM shows a closed h700mb over
swrn Nebraska Sunday evening and the 15z SREF has this feature
across ern Colo. If these solutions were to verify, snow could
easily reach into ncntl Nebraska, and perhaps elsewhere.
Attention is drawn to the potential for the coldest air of the
season to begin entering wrn and ncntl Nebraska next Thursday. This
event first came to light yesterday by the CPC and today`s runs of
the ECM and GFS, plus the ensembles continue to show this happening.
In fact, the CPC forecast today is predicting a 75 percent chance
for below normal temperatures next Thursday through the following
Monday.
Very strong upper level ridging across the N. Pacific into AK and
strong ridging across the N. Atlantic into Greenland will cause the
circumpolar vortex to pinch off forming an expansive upper level
low. The upper low will be displaced and free to drift west and
south across cntl Canada. The result will be a strong arctic sfc
high pressure system that will ridge very slowly south through the
Great Plains and the wrn U.S.. For this forecast, highs in the teens
and 20s are in place for next Thursday and this is a good start. The
temperature forecast Friday and beyond would likely feature
progressively lower temperatures.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 611 PM CST Thu Jan 4 2024
Widespread IFR/LIFR will persist tonight into Friday morning
across all of western and north central Nebraska. Conditions
will begin to improve some across far northern Nebraska during
the day Thursday. Ceilings may also lift some by late Thursday
afternoon across central into southern Nebraska. Winds will be
south to southeast about 5 to 10 kts.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST /11 AM MST/ Friday for
NEZ056>059-069>071.
&&
$$
SHORT TERM...
LONG TERM...
AVIATION...Taylor
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
954 PM CST Thu Jan 4 2024
.KEY MESSAGES...
- Overnight some light freezing drizzle is possible across
western and central Minnesota leading in some icy roads for
Friday morning.
- Light snow expected tomorrow afternoon through Saturday
night. Amounts will generally be under 2 inches, with highest
amounts in central MN into northwest WI.
- More light snow possible Monday as a powerful winter storm
passes to our southeast.
- Another round of snow possible Wednesday night into Thursday
followed by the arrival of much colder air.
&&
.UPDATE...
Issued at 933 PM CST Thu Jan 4 2024
A chance for freezing drizzle has been added to the forecast
overnight across western and central Minnesota.
The low clouds that have been with us over the last few days
continue tonight. Meanwhile warm air advection was commencing
across South Dakota and western Minnesota as seen on the SPC
Mesoanalysis H925 temperature advection. This was leading to
deeper moisture, and some freezing drizzle. Forecast soundings
show this environment continuing over night, so could see some
icy roads Friday morning. For now, have only added freezing
drizzle to the forecast, updated the HWO, and issued a small
Winter Weather Advisory, but we may need to expand the Winter
Weather Advisory if conditions worsen overnight and are expected
to linger into Friday before transitioning to snow.
&&
.DISCUSSION...
Issued at 220 PM CST Thu Jan 4 2024
TODAY through SATURDAY... Based on the 12z MPX sounding, the layer
of stratus around 3000ft is the only pocket of moisture holding on
as the surface high pressure dominates the Great Lakes region. With
that stratus layer within the DGZ, we`ve been seeing on and off
reports of light snow from central MN through western WI. A few
locations have been reporting brief reductions in visibility, as low
as 3 miles at times. Given the persistent cloud cover, lows tonight
have trended a bit higher and will safely stay in the low-mid 20s.
Friday afternoon through Saturday night will likely be a prolonged
light snow event, especially for central MN through northwest WI,
with amounts of 1-2" expected and 3" possible for some further
north. Two consecutive shortwaves will pass through the Upper
Midwest, ultimately resulting in a combination of WAA and a
saturated atmosphere starting Friday afternoon. The HRRR and NAMnest
continue to show a more expansive area of light snow, while the GFS
is keeping things much too dry for any noticeable accumulation. As
mentioned in previous AFD`s, we are favoring towards the guidance of
the hi-res models given their recent success handling low-level
moisture in the area. The main stretch of light snow will start to
move eastward during the day Saturday, in junction with a
passing cold front.
SUNDAY through TUESDAY... Slight ridging and a surface high to the
north will give us a brief break on Sunday, before a deep,
negatively tilted trough cuts through the central CONUS Monday
through Tuesday. The main impacts for our area will be a downward
trend in temperatures and any light snow associated with the precip
shield on the northwest side of the system. Accumulations should
only be around an inch or so, depending on how far southeast the low
center continues to shift.
WEDNESDAY through THURSDAY... Our third, and potentially best shot
at seeing accumulating snow will come some time mid-late next week
as a deep trough sets up over the central CONUS. While there
continues to be a bit of spread across models with this system, it
is worth noting that the NBM increased from slight chance to chance
PoPs with its most recent run. QPF is also right around, or slightly
above, 0.5 inches right now. Following this system, we`re expecting
to see a southward push of cold and dry continental air across the
region.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 546 PM CST Thu Jan 4 2024
MVFR conditions throughout with overcast skies near 2000 ft.
Winds will remain southerly. There is a small chance for some
freezing drizzle overnight at KRWF/KAXN, but did not mention it
in the TAFS. Otherwise expect snow to move into Minnesota late
Friday afternoon, and spread across the region Friday night into
Saturday.
KMSP...MVFR conditions with clouds just above 2000 ft this
evening, lowering to just below 2000 ft overnight, and then
lingering just above 2000 ft on Friday. There is a small chance
for snow (and possibly freezing drizzle) starting as early as
Friday, but for now only have snow mentioned after 00Z. Snow
should be primarily MVFR, with a few hours of IFR possible.
Accumulations should be less than an inch.
/OUTLOOK FOR KMSP/
SAT...MVFR/-SN with IFR possible. Wind SW 5-10 kts.
SUN...MVFR. Wind NW 5-10 kts.
MON...VFR with MVFR possible late. Wind ESE at 10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Winter Weather Advisory until 9 AM CST Friday for MNZ047-
054>056-064.
WI...None.
&&
$$
UPDATE...JRB
DISCUSSION...BED
AVIATION...JRB
Area Forecast Discussion
National Weather Service Omaha/Valley NE
503 PM CST Thu Jan 4 2024
.KEY MESSAGES...
- A couple of weak weather systems will bring a 20-30% chance
for scattered light snow showers on Friday night, and a chance
for flurries/light snow showers on Saturday night.
- A significant snow system once continues to take aim at the
area early Monday into the overnight hours.
- Most of eastern Nebraska and southwest Iowa currently hold a
greater than 50% chance of seeing 6" of snow based on latest
model trends.
&&
.DISCUSSION...
Issued at 415 PM CST Thu Jan 4 2024
Today and Tomorrow:
Water vapor imagery this afternoon shows a pronounced trough rooted
over the Rockies with dominating high pressure at the surface rooted
over the Great Lakes region leaving southerly flow and surface warm
air advection that has helped result in areas of reduced visibility
we some residual snowpack/enhanced soil moisture exists. These areas
of reduced visibility are expected to continue to hold over
central and northeast Nebraska through the overnight hours with
some increase in coverage slightly eastward possible overnight
as we cool down slightly a few degrees past the current
dewpoints in place with lows right around 25 or 26 degrees. Any
areas of slickness will join the lowered visibility as
temperatures continue to hold below freezing, especially on
elevated surfaces.
For tomorrow, the main story continues to be transient light snow
that could amount to a dusting to a few tenths of an inch of snow.
These snow showers would move into the area from south into
southeast Nebraska after 2 PM, with snow being possible in Omaha
largely from 6 PM to midnight. Recent runs of the extended HRRR
show light snow lingering into the overnight hours to around 4
or 5 AM in northeast Nebraska, which would push totals closer to
0.5" of snow.
Saturday and Sunday:
For Saturday, a quick moving shortwave will make its way to the
area, picking up some of the leftovers left behind from the
aforementioned trough currently over the Rockies, being joined
by a sagging cold front from the north that stalls out over
eastern Nebraska. Light snow will develop in northeast Nebraska
with very little moisture to work with, and as a result very
little to no accumulation is expected. Highs during the weekend
will continue to hold in the current pattern of the mid-to-lower
30s with grey skies continuing to linger.
Monday and Beyond:
The main story of the forecast period continues to be the impactful
snow system that is taking aim at the Central Plains, with some
portion of our forecast area likely (80% chance) to see 6 inches of
snow or more if recent runs of the global ensembles are to be
believed. Taking a look a the synoptic scale, a notably strong jet
is expected to develop over the Pacific Coast Sunday,
translating southeast followed by the development of a quick-to-
deepen lee surface cyclone that overspreads the area with snow
Monday morning and affecting the morning commute Monday. As it
stands currently, ensemble model solutions have converged
considerably with the question now being how deep the system
becomes, affecting the heaviest snow. 14 out of the 30 GEFS
members have Omaha receiving 6 to 12 inches of snow, with the
EPS showing a 50 to 60% chance of seeing 6 inches or more of
snow. The heaviest axis of snow currently lies near Falls City
in our area, where 8 out of the 30 members of the GEFS show 10
inches of snow or more; aided by strong signals for
frontogenetically-banded snow. Additionally, gusty winds of 25
to 30 mph would accompany areas of snow Monday; complicating
visibility and driving conditions further. While the forecast
continues to converge, enhanced caution is needed for those
traveling Monday into the overnight hours.
Beyond Tuesday, models continue to depict a late-week trough
Thursday, crushingly cold temperatures to finish the work week
before another potential snow system during the weekend. It`ll be
hard to bet on anything beyond the dynamic system Monday, but we
certainly have found ourselves in an active winter pattern.|
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 500 PM CST Thu Jan 4 2024
Cloudy through the period. LIFR conditions at KOFK, becoming IFR
by 16z, and MVFR by 18z. IFR at KLNK, with a period of LIFR
possible 06-10z, but back to IFR by 13z, and then MVFR by
14-15z. MVFR at KOMA until about 17-18z. There could also be
snow or rain showers that develop in the vicinity of KLNK by
20z, and KOMA by 22z-24z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Petersen
AVIATION...DeWald
Area Forecast Discussion
National Weather Service Pueblo CO
246 PM MST Thu Jan 4 2024
.KEY MESSAGES...
- Winter storm will impact the Plains tonight into Friday morning.
- Going Winter Weather Advisories look good.
- Snow Friday night and Saturday morning, with mostly dry and cool
conditions the rest of the day Saturday.
- Potential remains for an impactful winter storm system for the
end of the weekend and start of next week.
- Active and unsettled pattern continues into the middle of
next week.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 242 PM MST Thu Jan 4 2024
Key messages:
- Winter storm will impact the Plains tonight into Friday morning.
- Going Winter Weather Advisories look good.
Currently...satellite imagery shows a large upper level low across
central New Mexico early this afternoon, which will track slowly
east-northeast through tonight. Radar is starting to fill in across
the Plains with light snow seen along most of the I-25 corridor.
Temperatures have remained cool this afternoon with upper 20s to
lower 30s for most areas on the Plains.
Tonight...the upper level low is forecast to drift east-northeast
out of central New Mexico into northwest Oklahoma by morning.
Satellite imagery shows a surge of moisture working northward into
southern Colorado, and flow is currently transitioning to
southeasterly across the Plains asa 700 mb low develops near
Trinidad. There appears to be a period for this evening, from 5 PM
through around 3 AM, where deeper upslope flow, warm air advection
and isentropic lift will be focused across the southern half of the
Plains. Weak instability, with MUCAPE value around 50 j/kg and SREF
omega probabilities in excess of -6 microbars/sec around 70%,
indicate and enhanced period of snowfall along the New Mexico
border. The main question is how far north this higher intensity
band of snow may make it. The HRRR has been consistent throughout
the day with the heaviest snowfall centered over eastern Las Animas
and Baca Counties. Increased snowfall amounts there with an earlier
update and the current totals, in the 3-6 inch range look good. The
past couple of runs of the HRRR have been developing a band along
Highway 50 of light to moderate snow, with accumulations of 1-3
inches this evening. Based off the latest high-res guidance, the
current snowfall totals along the Highway 50 corridor look good. But
any slight shifts in the forecast track and upper dynamics could
shift the heaviest snow band from along the New Mexico border, north
towards the Highway 50 corridor.
The other thing eastern Las Animas and Baca Counties have going for
them, is duration. Flow in this area will likely remain
southeasterly for a longer period as the upper system ejects into
northwest Oklahoma. For other areas of the Plains, flow will turn
from easterly to northwesterly by 3 AM, becoming downslope and
shutting down upslope snow production. Snow across the I-25
corridor should quickly come to an end as winds shift. But for Baca
County, flow will likely continue to be southeasterly until around 6
AM, and snow will likely carry on for a longer period of time.
As mentioned, snow will taper off across all but the far southeast
Plains after 3 AM as flow turns northwesterly. Given the cloud
cover across the region, temperatures will remain steady overnight
with mostly mid 20s on the Plains.
Friday...the upper low will continue to lift northeast out of
Oklahoma and into western Iowa by Friday afternoon. Snow will come
to an end over the far southeast Plains Friday morning as flow
finally turns northwesterly. Broad northwesterly flow aloft will
keep the Plains dry through the afternoon hours. Weak energy
embedded in the flow ahead of the next incoming system will likely
keep periods of light snow going over the Mountains. Snow
accumulations of 1 to 3 inches may be possible, mainly along west
facing slopes. Limited warming is forecast on Friday, and highs on
the Plains will top out in the mid to upper 30s. Mozley
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 242 PM MST Thu Jan 4 2024
Friday Night - Saturday: The start of the weekend will begin with
wintry weather early, with a brief period of quieter weather later
Saturday. Synoptically, a trough will pass over southern Colorado
Friday night, and will then begin exiting the region early Saturday.
As this wave passes over the area, isolated to scattered pockets of
light snow will increase across the area, primarily over the
mountains, in response to the uptick in forcing. As the system exits
the region early Saturday, ascent will lessen, and
northwesterly/northerly winds will materialize. Given this, any
pockets of snow present early Saturday morning are expected to
quickly lessen in coverage throughout mid to late morning, with only
isolated pockets of snow remaining along the mountains the rest of
the day. As for temperatures, a cool day is expected for the area.
Given the active pattern in place, cooler air will remain across
southern Colorado, with much of the area around to slightly
below seasonal values.
Sunday - Monday: The end of the weekend and start of next week will
bring the next larger and possibly more impactful storm system.
Deterministic and ensemble model guidance remain in relatively good
agreement about digging a trough southward over the area, and
developing a closed low as it does so. This pattern would bring
heightened chances for snow across much of south central and south
eastern Colorado as the storm system wraps over the region. Just
like previous thinking though, the track of the low and strength
will play a significant role in what ultimately materializes for the
area, and recent model trends have shifted slightly further south.
This would mean more impactful snow becoming restricted along
prominent terrain features such as the mountains and Palmer and
Raton ridges. Overall, the synoptic pattern is still on track to
bring a closed low over the area, but the eventual track and
strength will still need to be honed in in the coming days. Along
with snow chances, gusty winds are likely throughout this period,
particularly Monday as the low deepens to the south/southeast. While
there`s currently no major signal for strong winds, any gusty
winds combined with the potential snow could cause further
impacts. Looking at temperatures, a cold couple of days is
expected. With the system passing over, reinforcement of colder
air will take place, and much of the region will remain below
seasonal values.
Tuesday - Wednesday: For around the middle of next week, an overall
active and unsettled pattern is expected to continue for the south
central and south eastern Colorado areas. Model guidance show a
brief ridging pattern within the Tuesday timeframe, with more
troughing developing late Tuesday and onward. While a downtick in
active weather would be expected Tuesday as the ridge pushes over,
beyond that, precipitation chances increase again for the region,
especially along the mountains. As for temperatures, cool values are
anticipated to remain in place. With that active pattern persisting
and the cool are still across the area, much of southern Colorado
will remain around seasonal values.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 242 PM MST Thu Jan 4 2024
KALS...a few snow showers will remain possible across the San Luis
Valley through this afternoon, but confidence in one hitting the
terminal are low. Briefly reduced CIGS and VIS would be the main
impacts if a snow shower does it the terminal. IFR to MVFR CIGS
will improve overnight into Friday afternoon.
KCOS and KPUB...snow showers are currently lifting north across the
terminals. Brief periods of reduced CIGS and VIS will remain
possible early this afternoon. Snow will fill in at both terminals
this evening with MVFR to IFR conditions due to low CIGS and VIS.
KPUB will likely see the heavier snowfall this evening. Snow will
come to an end late tonight, with CIGS and VIS improving into Friday
morning and afternoon. Mozley
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 PM MST this evening for
COZ068.
Winter Weather Advisory until 5 AM MST Friday for COZ074-075-
079-080-087-088-094-099.
&&
$$
SHORT TERM...MOZLEY
LONG TERM...SIMCOE
AVIATION...MOZLEY