Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/30/25
Area Forecast Discussion
National Weather Service Denver/Boulder CO
712 PM MST Wed Jan 29 2025
.KEY MESSAGES...
- Snow develops across the plains tonight, spreads into I-70
corridor east of Denver and over the Palmer Divide by early
morning.
- Snow will lead to a slick morning commute for areas south and
east of Denver.
- Warmer but breezy Friday through the weekend. Lots of
uncertainty with the magnitude of a backdoor cold front Sunday
night into early next week.
&&
.UPDATE...
Issued at 712 PM MST Wed Jan 29 2025
The 18Z model runs as well as the 00Z NAM and HRRR seem to have
finally closed in on a solution, keeping the heavier band of snow
associated with the TROWAL east of the Denver area. General
consensus is this band ends up forming over Elbert, eastern
Adam/Arapahoe, and Washington Counties. Lighter snowfall is still
expected east of this band. To the west, most of the models show
light snowfall (less than 2 inches) and some models now showing no
snowfall for Denver. The best chance for snow in the Denver area
will be late tonight into Thursday morning (3AM to 10AM) before
the band of heavy snow and gusty north winds form. Dry is over the
area and to the north over Wyoming. Once the northerly winds
develop, snow is expected to end along and west of the I-25
corridor as dry air is transported into the area.
As far as changes to the forecast goes, increased PoPs and snowfall
amounts to the east of the Denver area, across Elbert, eastern
Adam/Arapahoe, and Washington Counties. If heading east on I-70 out
of Denver, expect to encounter snow covered roads and hazardous
travel through early to mid afternoon. We also lowered PoPs and
snowfall amounts west of I-25, all the way west into the mountains
and foothills. Conditions for freezing rain/drizzle still exist over
the northeast plains, but the 18Z models trended away from freezing
rain/drizzle. Though wouldn`t be surprised to still see a little, so
left the mention of freezing rain in the forecast, but decreased the
chances and ice amounts in the forecast.
&&
.SHORT TERM /Through Thursday/...
Issued at 231 PM MST Wed Jan 29 2025
There are still a few questions left unanswered as they relate to
our upcoming storm system, but there`s one aspect where confidence
is high: Whether in the snow-lover camp or not, many folks will be
sorely disappointed, and many will be quite pleased once the snow
wraps up. Such is the beauty of a banded snow event!
Let`s first take a few steps back though. Sun abounds this afternoon
as we await the approaching system, with mild southerly flow in
place along the leading edge of the closed low, which is currently
sitting over north-central Arizona. In our southeast plains, clear
skies are rapidly giving way to an expanding stratus deck as this
southerly flow advects a tongue of healthy Gulf moisture into the
region. By this evening, cross-sections indicate deepening mid-level
moisture that would support gradual development of showers in the
eastern plains, especially Lincoln/Washington Counties. Marginal
surface temperatures could support a brief rain shower or wintry mix
during the onset of precipitation, but a changeover to snow
shouldn`t be far behind for *most* areas (caveat to come shortly).
As the front occludes overnight, a pronounced NE-SW TROWAL will
develop through the early morning hours from the northern plains
into the Palmer Divide. One effect of the warmer air aloft will be
to sustain a warm nose near 800mb across the northeast plains, which
opens the door to a period of freezing rain or a wintry mix for
those areas as surface temperatures drop below freezing. Have thus
introduced this into the forecast.
The TROWAL will also enhance low-level frontogenesis, promoting a
transition to more of a banded snow event by Thursday morning, which
will carry potential for a period of moderate to heavy snow with
rates near 1"/hr for several hours to the southeast of Denver.
Models have a loose idea - rather than a firm hold - on the
placement of this band of heavier snow, but the area of greatest
confidence in heavier snow Thursday morning extends from the Palmer
Divide northeastward (where northerly upslope flow will be
maximized), and across the I-70 corridor between Bennett and Limon.
With high confidence in impacts for the morning commute, a Winter
Weather Advisory was issued for these areas. Adjacent plains zones
(e.g. Morgan, Washington, southern Lincoln Counties) were included
to capture spatial uncertainty in the banding. Additionally, hi-
resolution guidance remains rather steadfast in amplifying QPF
across our southern foothills. However, still believe this is
overdone in some of the recent runs, considering less-than-favorable
north/northwest winds. This will also keep areas to the north of
Denver largely dry.
So with all of that said, there`s reasonable confidence in little to
no impacts for the mountains, northern foothills, and northern I-25
corridor extending from the NW Denver suburbs to the WY border. The
axis of greatest uncertainty will be focused across the SW Denver
suburbs towards DIA and the northeast plains, where a steep snowfall
gradient can be expected. The most favored locations under the
heavier snow band may well receive 5-10" when all is said and done
in/near the Palmer Divide, but such amounts won`t be overly
widespread. Snow will ramp down quickly by midday as breezy
northerly winds develop across the lower elevations, with
temperatures likely climbing into the 40`s for snow-free areas of
the plains and urban corridor.
&&
.LONG TERM /Thursday night through Wednesday/...
Issued at 231 PM MST Wed Jan 29 2025
Dry conditions are expected across the forecast area Thursday night
as the 500MB upper low moves be over the Central plains states and a
dry northerly flow sets up over Colorado. On Friday, dry and warmer
conditions are expected over the CWA as an upper level ridge of high
pressure builds over the state. Colorado will be under the influence
of a zonal flow aloft this weekend with some downsloping flow east
of the mountains. This pattern will result in mild and dry
conditions across the plains with high temperatures ranging from the
mid 50s to lower 60s. There may be enough mid level moisture caught
up in the flow to produce a 20-50% chance of light snow across the
high country over the weekend. In addition, the pattern will produce
breezy to windy conditions across the high country Friday night
through the weekend with wind gusts to 65 mph possible across the
Front Range Mountains and foothills.
For the Monday through Wednesday period, the zonal flow aloft
continues with some weak upper level ridging over the region. The
high country should see a continued 20-50% chance for light snow due
to some mid level moisture combined with orographic lift. There is
quite a bit of forecast uncertainty east of the mountains due to
model differences. The GFS Deterministic and GEFS Ensembles are
suggesting a cold front moving across the eastern plains Monday
morning with a shallow cold air mass settling in behind it. This
scenario would result in much colder temperatures on the plains with
daytime readings only climbing into the 30s along with the
possibility for some very light snowfall. On the other hand, most of
the other models keep the front north of our CWA with warm and dry
weather continuing. An example of this would be the ECMWF and GEM
deterministic solutions which are showing Denver`s max temperatures
climbing into the lower 70s both Monday and Tuesday afternoon.
However, it would most likely be cooler than this since these
solutions are outliers. For now have decided to go with the
forecast model blend which has high temperatures in the mid 40s to
mid 50s on the plains.
&&
.AVIATION /00Z TAFS through 00Z Friday/...
Issued at 438 PM MST Wed Jan 29 2025
Clouds will continue to creep north bringing ceilings of 6000 to
8000 feet after 00Z. Ceilings are expected to fall below 6000 feet
03Z to 06Z and continue to lower, falling below 3000 feet towards
12Z Thursday. Growing confidence the heavier snow stays just east
and southeast of DEN. Though light snow is still expected, mainly
in the 10-17Z window. Winds to stay light the rest of the
evening, and then pick up out of the north around 12Z with gusts
to 25 knots possible much of the day Thursday. The snow and
clouds shift east of the area after 18Z with VFR conditions
expected by 21Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 AM to 2 PM MST Thursday for
COZ041-044-045-049.
Winter Weather Advisory from 11 PM this evening to noon MST
Thursday for COZ046-047.
&&
$$
UPDATE...Meier
SHORT TERM...Rodriguez
LONG TERM...JK
AVIATION...Meier
Area Forecast Discussion
National Weather Service Dodge City KS
835 PM CST Wed Jan 29 2025
.KEY MESSAGES...
- Powerful weather system will bring widespread light rain to
southwest KS in two waves Wednesday evening and Thursday
evening with small (0.1-0.25 inch) accumulations.
- Fog development is expected Thursday morning impacting much of
SW Kansas with some areas seeing chances (30-50% via
ensembles) for dense fog development.
- Above normal temperatures and quiet weather returns to southwest
KS this weekend.
&&
.UPDATE...
Issued at 828 PM CST Wed Jan 29 2025
Update this evening will focus on fog potential Thursday
morning.
Scattered convection was spreading north across southwest and
south central Kansas as of 8 PM CST. CAMs have a good handle on
this convection early tonight as the nose of a 500mb jet
approaches southwest Kansas and mid level cooling occurs ahead
of a 500mb low located in southwest New Mexico. The latest CAMs
not on had a good hand with this but also remains consistent
with previous runs moving this area of convection north of the
I-70 corridor after 06Z as areas of fog develop.
The latest 18Z and 21Z ensembles earlier today, along with
latest CAMs visibility/BL RH this evening are now more
aggressive with fog development once the rain tapers off, with
a few locations having a greater than 70% chance of visibility
dropping to 1/2 mile or less. Confidence however in just how
low the visibilities will get early Thursday morning and how
widespread this fog will be remains low (30-50%). Despite this
low confidence in the widespread dense fog potential, anyone
with travel plans should be prepared for local visibility
reductions to less than 1/4 mile at times. Continue to monitor
the latest forecast in case a dense fog advisory is issued.
The best chance for these low visibilities will be between 3 AM
and 9 AM Thursday morning. After 9 AM, the fog will gradually
dissipate, giving way to breaks of sunshine during the afternoon
as the upper low moves across western Kansas.
&&
.DISCUSSION...
Issued at 316 PM CST Wed Jan 29 2025
The deep cut-off low pressure system continues to move slowly
eastward. A weak low-level high pressure system has developed over
the Rockies illustrated by RAP mesoanalysis. This created a subtle
Rex Block-like pattern in conjunction with the strong low pressure
system. The system has already brought widespread cloud cover with
lower ceilings for the entire CWA except the northern-most counties.
Later this afternoon around 4-5 PM, widespread light rain showers
are expected to develop and move northward into the forecast area.
These showers are forecast to last into the night, fully dispersing
shortly after midnight. Trends in ensembles continue to have the
system move faster and be warmer; lighter accumulations and nearly
no snow is expected as a result. No part of the CWA has a >10%
chance from ensembles for snow through the duration of this system.
Thursday morning, models and ensembles alike have picked up on a
strong likelihood for fog development with ensemble mean
visibilities dropping to 1 mile in some areas. Nearly all of SW
Kansas has been encompassed by this trend with only the far SW
corner being excluded. The extent of how dense the fog develops and
how expansive the densest areas evolve still hold a bit of
uncertainty, but routine fog precautions should be taken Thursday
morning.
Thursday afternoon into the evening precipitation chances return,
although it will be much more limited spatially and with regards to
accumulations. Again virtually no snow is expected; total liquid
accumulations from the system range primarily between 0.1-0.2
inches. Especially if the precipitation develops in a raggedy
pattern, localized amounts could vary a few tenths from this range
in either direction. Overall, with the near exclusively liquid
precipitation and low accumulations, no impacts are expected beyond
the visibilities and lowered cloud cover.
The weather pattern quiets back down Friday into the weekend.
Synoptically, ensembles have a zonal flow regime fill the vacuum
left by the vacating low pressure system as it continues to push
eastward. Ensembles blanket the weekend with highs in the 60s for a
warmer than normal start to February. Ensembles keep the very quiet
stretch until at least the middle of next week. Ensembles then hint
at a shortwave trough development bringing chances of precipitation
back into the CWA. With these chances being relatively low (<30%)
and it being very far out regarding a small feature, great
uncertainty should be reserved until more time elapses.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 508 PM CST Wed Jan 29 2025
Light rain showers and IFR ceilings will develop through 03z
tonight, with a 60-90% chance of LIFR ceilings and reduced
visibilities between 03Z and 09Z Thursday.
CAMS and short term ensembles remain in good agreement, showing
ceilings lowering to 500-1000ft AGL by 03Z Wednesday as
scattered light rain moves across southwest Kansas. There is a
50-60% chance of ceilings dropping below 500 ft at times in
Garden City, Dodge City, and Hays, with the greater likelihood
of LIFR ceilings after 03Z (+70%) as steadier rain showers move
in. Hays will see these low clouds and rain showers between 03Z
and 09Z tonight. The rain will taper off south to north between
midnight and 12Z Thursday, and as it does, fog development will
need to be monitored closely. Latest guidance and HREF
visibility probabilities indicates as >70% chance of ceilings
falling below 1 mile and a 40-60% chance of visibilities
dropping to 1/2 mile. Light winds late tonight and early morning
favor LIFR conditions, so trends will be adjusted accordingly.
After daybreak, BUFR soundings and CAMS suggest gradual
improvement to VFR conditions after 18z Thursday.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Burgert
DISCUSSION...KBJ
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Hastings NE
559 PM CST Wed Jan 29 2025
.KEY MESSAGES...
- By far the most active weather (but admittedly probably not
very "high impact") occurs right away during the first 36
hours, as various parts of our coverage area (CWA) will see
mainly isolated-scattered rain showers (maybe even a few
rumbles of thunder?), at least patchy fog (mainly south) and
MAYBE a touch of brief freezing rain (mainly north).
- Although any areas with narrow bands/splotches of brief
heavier rain could be an exception, overall rain totals over
the next 36 hours have continued to trend downward, with MOST
of our CWA now forecast to receive no more than 0.10-0.30
(some areas less and probably only a few more).
- Not that it was a major concern to begin with, but it appears
that any threat for a potential narrow band of slushy snow on
the "backside" of the departing area of precip late Thurs
night-early Fri AM has trended even lower, and in fact we have
no snow accumulation whatsoever depicted in our official
forecast.
- Temperature-wise: the next week as a whole will clearly
average out above normal (particularly Fri-Sun), with a
chillier (but certainly not overly-cold for early-Feb!)
airmass arriving Mon-Wed.
&&
.DISCUSSION...
Issued at 436 PM CST Wed Jan 29 2025
-- PRIMARY 7-DAY FORECAST CHANGES/UNCERTAINTIES/BIG PICTURE
COMMENTARY (mainly on the incoming low pressure system):
- Big picture wise, the vast majority of forecast "brain
power"/attention today was spent on these first 36 hours,
which despite featuring the passage of a seasonably-strong
upper level low pressure system through the Central Plains,
also appears to pack a surprising "lack of impact" for our
CWA. Quite simply, this system is not expected to feature
accumulating snow/widespread icing/strong winds or even severe
thunderstorms...all of which are either regularly or rarely a
possibility around here...even in mid-winter.
- By far the most noticeable change from our AM "forecast
package" was a continued whittling away at expected rainfall
totals. As touched on above, MOST areas will be lucky to
exceed 0.10-0.20", BUT as is almost always the case with
strong low pressure system (and especially with weak
instability in play), there will probably be localized
exceptions that perhaps manage to pick up around 0.50" or
slightly more.
- Fortunately, and despite quite a bit of frost still in the
ground, the warmth of the last few days has allowed the top
few inches of soil to start thawing a bit, so unless rainfall
exceeds expectations or happens to come down fairly hard in
localized areas for a time, we are not very concerned with
"true" flooding...only some enhanced minor ponding potential.
- THAT BEING SAID, there are a few lower-confidence (both in
terms of occurrence and areal coverage) potential hazards that
cannot be completely ignored, both of which are primarily
focused very late tonight into Thursday AM: 1) At least patchy
fog (possibly localized dense?), particularly near and south
of the KS border...2) A very low (likely no higher than 20%)
chance of light/brief freezing rain mainly within Nebraska
counties north of I-80. While neither of these potential
hazards are of high-confidence-in-occurrence, they are also
close enough in time that they could not be "ignored" for our
latest Hazardous Weather Outlook (HWOGID), which now contains
mention of potential fog, light icing and spotty non-severe
thunderstorms (obviously a rarity for late Jan...but also not
a "sure thing" either).
-- 7-DAY FORECAST CHRONOLOGICAL DETAILS (very heavily focused
first 36 hours):
- CURRENT/RECENT WEATHER SITUATION AS OF 330 PM:
As late January days go, this one ranked very high on the
"pleasant spectrum" for this forecaster. Although the very
leading edge of invading mid-level clouds has started creeping
northward into our KS zones this afternoon, the vast majority of
our CWA has enjoyed widespread sunshine. Following a morning
with very light winds, this afternoon has featured a slight
uptick in speeds...but still only mainly sustained around 10
MPH/sporadic gusts to around 15 MPH...mainly out of hte south-
southwest in Nebraska counties and southeast in our KS zones.
Although not quite to the extent as yesterday, high
temperatures will at least meet, if not very-slightly exceed our
earlier- forecast expectations most areas, with most places
topping out 55-58, and the main exception being the still
stubbornly-snow- covered areas of MItchell County KS in our
extreme southeast, where it at least made upper 40s.
In the big picture aloft, water vapor satellite and short term
model data clearly depict a large-scale/closed low pressure
system spinning over the AZ/NM border, with our flow aloft
turning increasing south-southwesterly as it approaches.
- THIS EVENING-OVERNIGHT:
In the big picture aloft, the aforementioned upper low will
continue its gradual march east-northeast...centered over the
CO/KS border by sunrise Thurs.
Pre-midnight: the vast majority of our CWA will surely stay
dry, but mid level (and eventually lower level) clouds will
continue a steady march northward out of KS. The exception where
pre- midnight rainfall is possible resides mainly in our KS
zones, where at least isolated/scattered rain showers and MAYBE
a few rumbles of thunder could start creeping in from the south
mainly after 9 PM.
Beyond midnight: This is when at least limited weather concerns
enter the picture. Starting with something of higher confidence,
at least isolated/scattered showers (perhaps a few weak
thunderstorms owing to as much as a few hundred J/kg of
elevated CAPE/instability) will continue spreading north out of
KS into our Nebraska zones...perhaps even spreading north of
I-80 by sunrise, but with considerably higher chances focusing
within counties south of I-80. This is where surface temps
become key, as tonight`s hourly temperature forecast is not very
straightforward. While southern areas (that see clouds arrive
first) will drop no lower than the mid-30s (above freezing),
especially our counties north of I-80 could remain clear long
enough for temps to drop perhaps as low as 27-32 degrees before
stabilizing (or even rising) with the arrival of increasing
clouds. The problem would be IF any spotty rain showers do
manage to get into areas that drop slightly below freezing, then
we could have at least very localized areas of freezing
rain/light icing for the AM commute. Again, this is of very low
confidence as the vast majority of our CWA should see "plain"
non-freezing rain overnight (if anything), but it`s just enough
of a threat that have introduced to HWO.
The other late night concern is whether any fog manages to
develop in the wake of northward-lifting showers/weak storms,
which IF were to occur appears most favored in our KS zones. For
now, have simply introduced basic "patchy fog" to the official
forecast while acknowledging for potential for visibility to
drop to 1 mile or lower in our HWO.
- THURSDAY DAYTIME-NIGHT:
Over the course of these 24 hours, the main upper low will
temporarily "stall out" over western/southwest KS during the
day, before then accelerating eastward overnight...reaching
northeast MO by sunrise Friday.
Right off the bat Thurs morning, we`ll need to monitor for
possible fog issues (which could creep up to roughly Highway 6
in Nebraska...but mainly pre-Noon), and for that lingering
slight chance of spotty light icing in our northern zones
(mainly prior to 9 AM).
Moving on to broader precip expectations, locally, our overall-
surprising lack of meaningful measurable precipitation
potential (for such a strong upper system) appears to mainly be
tied to unfavorable positioning of a mid-level dry slot. That
being said, at least spotty (if not localized more concentrated)
bands/splotches of rain showers will remain possible ALMOST
ANYWHERE at almost ANY TIME throughout the day and into Thurs
night, before the back (northwest) end of any potentially
organized precip shield gradually departs our south-southeast
zones late Thurs night. Even at this fairly "late in the game"
forecast time frame, models are admittedly fairly divided over
whether parts of our area pick up decent rain totals in excess
of 0.25", or whether most areas stay mostly dry. If anything,
the very latest 18Z HRRR indicates that a narrow, generally
west-east oriented zone potentially cutting through the Tri
Cities area COULD actually see some decent rainfall late Thurs
afternoon-evening, but again, this seems to be a bit of "wetter
outlier) compared to most models, and thus why our official rain
chances (PoPs) are currently mainly no higher than 30-50%. As
for thunderstorm potential Thursday daytime, it cannot be
totally ruled out (again on a weak/spotty basis), but opted not
to include a formal forecast mention at this time and will defer
to later forecasts to take a closer look.
Getting into the later night hours, there have been some
concerns about enough dynamic/internal cooling to take place
aloft within the departing upper low to allow the back end of
any departing rain band to change over to slushy/wet snow.
However, latest higher-res models have trended toward
downplaying this and keeping precip type as mostly/entirely
rain, so snow is currently not considered a likely hazard.
Touching briefly on temperatures/winds for Thurs-Thurs night,
nudged down highs slightly (no mainly mid 40s), and make little
to change to lows, with most areas eventually bottoming out
upper 20s-low 30s and not dropping notably until after
precip/clouds depart. Wind-wise, the lack of a defined surface
low will keep speeds during the day light (mainly 5-10 MPH at
most, turning more northerly with time), while Thurs night will
feature a slight uptick to sustained 10-15 MPH/gusts around 20
MPH.
- FRIDAY-FRI NIGHT:
In the wake of the departing system, high confidence dry weather
returns as our flow aloft flattens back out to more zonal (west-
east). Under plentiful sunshine, high temps were nudged up a few
degrees, now ranging near-50 northeast to upper 50s southwest.
It will be slightly breezy, with gusts around 20 MPH out of the
northwest especially Fri AM, before winds gradually swing around
to southerly Fri night, keeping lows up into the mid-upper 20s
most areas.
- SATURDAY-SUNDAY:
Overall, a pretty darn nice/mild weekend to kick off February!
We have high temps both days aimed well into the upper 50s-low
60s. It could be a little breezy (but probably not overly-
windy), but even so will have to watch for at least low-end fire
weather concerns given the warmth.
- MONDAY-WEDNESDAY:
High confidence that the vast majority of this time frame
remains precip-free (our official forecast currently reflects
this), but both ECMWF/GFS hint that at least spotty rain or snow
could be lurking somewhere in our general area at times, so will
have to keep an eye on this. Temperature-wise, as it typical of
the extended periods, uncertainty does grow, as there are at
least modest differences in how quickly and how much so we cool
down behind a cold front slated to pass through sometime between
Sunday afternoon-Sunday night. For now no big changes from
previous, with highs Mon mainly upper 30s-mid 40s, and Tues-Wed
most areas somewhere in the 30s. Certainly nothing of truly
Arctic origin.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 555 PM CST Wed Jan 29 2025
For KGRI/KEAR Airports:
Significant weather: made some fairly significant changes to the
latest TAFs based on latest trends - which are for lesser
chances of IFR conditions tonight into Thursday. Details below:
Tonight: VFR conditions and gently Srly flow will continue
through at least midnight. After midnight, particularly towards
08-10Z, expect scat shwrs to begin to move in from the S. Can`t
completely rule out a few rumbles of thunder, as well. As the
shwrs arrive, appears CIGs will fall to MVFR levels, and perhaps
VSBYs as well in the stronger cores. Believe both terminals
will receive at least a trace by 12Z, but coverage of heavier
showers and possible MVFR VSBYs and near-IFR VSBYs remains more
uncertain, so kept these conditions as a PROB30 group for now.
Winds will go lgt and vrbl by dawn. Confidence: CIGs/VSBYs - low
to medium, wind - high.
Thursday: Now appears that the initial surge of shwrs will
dissipate pretty quickly around, or just after, sunrise...with a
period of mainly dry conditions now favored from mid-late AM
through around midday. This makes widespread/persistent IFR
conditions (CIGs <1000ft) less likely, so have backed off to
MVFR as 1500-2000ft is now more favored. During the aftn, esp.
mid to late aftn, some guidance redevelops a relatively
organized band of shwrs which could force conditions down to IFR
CIGs and MVFR VSBYs, but given uncertainties and this being the
last 6 hrs of the period, only went with PROB30 groups for now.
Lgt and vrbl winds will turn NWrly during the aftn. Confidence:
Low to medium.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
DISCUSSION...Pfannkuch
AVIATION...Thies
Area Forecast Discussion
National Weather Service Goodland KS
851 PM MST Wed Jan 29 2025
.KEY MESSAGES...
- Precipitation (mainly rain) will overspread the region from
south to north tonight through Thursday evening for locations
generally east of the Colorado/Kansas border.
- Precipitation (a mix of rain, snow, sleet and maybe some
freezing rain) is expected tonight with snow Thursday morning
across eastern Colorado. Rain chances during the afternoon.
Snowfall amounts generally zero to 2 inches, highest west of a
line from Yuma to Flagler with slightly higher amounts
possible.
- Above to much above normal temperatures for Friday through
Sunday.
- Considerable uncertainty regarding temperatures Monday through
Wednesday.
&&
.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 235 PM MST Wed Jan 29 2025
Tonight...an upper level low pressure area, currently spinning over
the Arizona/New Mexico border area this afternoon, will slowly
deepen as its center moves into southwest Kansas overnight. A plume
of moisture in the 850-700mb layer steadily lifts northward across
the area through much of the night, pivoting into a northeast to
southwest orientation after midnight from roughly McCook to Goodland
and Cheyenne Wells west. Below this layer, the boundary layer will
be saturated. The highest precipitation chances (40%-80%) follow
this scenario through about midnight before decreasing into the 20%-
60% range west of the McCook to Goodland and Cheyenne Wells line
mentioned above.
Precipitation type remains troublesome. Most of the models have rain
generally east of the CO/KS border through midnight with primarily
snow to the west. High res models and HRRR runs show a rain/freezing
rain combination along the CO/KS border with generally snow and
maybe some sleet to the west. Generally speaking, rain is
anticipated east of Highway 27 with a wintry mix along the CO/KS
border and some type of snow and/or sleet possibility in far eastern
Colorado. After midnight, it looks more like rain generally east of
the CO/KS border with snow to the west. Snowfall amounts generally
under an inch across far eastern Colorado.
With surface dewpoints slowly increasing overnight, low temperatures
should be rather mild with the forecast calling for 29F to 35F. It
should also be mentioned that there is a high likelihood of fog
developing behind the precipitation shield with dense fog possible.
Thursday-Thursday night...the storm center is forecast to move
slowly east into southern Kansas by the end of the day and near the
Kansas/Missouri border overnight.
The 850-700mb relative humidity axis (wraparound precipitation
shield) continues for those along and west of Highway 27 during the
morning before weakening during the afternoon. Morning precipitation
chances (20%-60%) will be in this area with dry conditions
elsewhere. Additional snowfall amounts up to an inch, maybe higher
are forecast across far eastern Colorado, mainly from Yuma to
Flagler west. The afternoon hours may see a few light showers with
chances only 20% given the abundant low level moisture. High
temperatures are forecast to be in the middle 30s to upper 40s,
coldest across far eastern Colorado.
For the overnight hours, there may be one last chance for some light
measurable precipitation through midnight for those generally east
of the CO/KS border before the moisture exits the area. Low
temperatures are forecast to be in the lower to upper 20s.
Friday-Friday night...broad upper level ridging moves over the area
during the day, becoming zonal overnight. Lots of sunshine expected
for much of the day. High temperatures are currently forecast to be
in the lower 50s to around 60, coolest across the Yuma to Flagler
areas where some snow cover is possible. Under increasing high
cloudiness, low temperatures fall into the 25 to 30 degree range.
Saturday-Saturday night...dry weather is expected under some
scattered to broken high cloud cover. High temperatures rise into
the middle 50s to middle 60s. Low temperatures are forecast to be in
the the upper 20s to lower 30s.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Issued at 235 PM MST Wed Jan 29 2025
Sunday...dry weather is currently forecast as 850-500mb relative
humidity forecasts remain low. There continues to be a very high
amount of uncertainty regarding the high temperature forecast with
GEFS/GFS/ECMWF/UKMET/EPS all having a 30 degree difference amongst
each other. The current forecast is calling for highs in the 60 to
65 degree range but with a spread of up to 20 degrees in the NBM
75th-25th percentile, a large swing colder or warmer remains
possible. Low temperatures are currently forecast to be in the lower
to upper 20s.
Monday...dry weather continues. An even larger temperature spread
amongst the high temperature guidance exists. The coldest guidance
(GFS) has highs in the 20s and 30s while the warmest guidance (GEM
model) has highs in the 60s and 70s. Presently, highs are forecast
to be in the middle 40s to middle 50s, a bit warmer compared to 24
hours ago but given the large model discrepancy, changes are likely
and dependent on whether or not arctic air moves in or not. Low
temperatures are forecast to be in the middle teens to middle 20s.
Tuesday...no precipitation expected as better moisture remains well
north of our area. High temperatures are forecast to be in the upper
30s to near 50, but with a continued high spread in model guidance
changes are likely. Low temperatures are forecast to be in the
teens.
Wednesday...similar to the prior few days, higher than normal
uncertainty regarding the temperature forecast. Current forecast is
calling for highs in the 30s to near 40 with dry weather
continuing.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 850 PM MST Wed Jan 29 2025
For KGLD, the terminal will see ceilings ranging from OVC003-010
through 02z Friday before going VFR. Light rain/fog through 18z
Thursday may drop visibility from 1-5sm. Winds, light/variable
through 18z then north-northwest around 10kts.
For KMCK, the terminal will see MVFR ceilings through 13z
Thursday, then IFR or lower BKN002-010 through 21z. MVFR
ceilings return from 21z Thu-03z Fri, then VFR thereafter.
Light rain/fog could drop visibility to 3-4sm at times from
13z-21z Thursday. Winds, light/variable through 21z, then
north-northwest around 10kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...99
LONG TERM...99
AVIATION...JN
Area Forecast Discussion
National Weather Service Marquette MI
948 PM EST Wed Jan 29 2025
.KEY MESSAGES...
- Winter Weather Advisories for Alger and northern Schoolcraft
counties have been extended to 21Z and Luce County to 00Z as
NW wind lake effect snow lingers this evening.
- A passing disturbance to bring light snowfall overnight into Thursday
morning, little to no impacts expected.
- A system moving through the Great Lakes brings the next best
chance of widespread snow Saturday night into Sunday.
&&
.UPDATE...
Issued at 948 PM EST Wed Jan 29 2025
The forecast remains on track tonight. Lake effect snow over Luce
and Alger counties continues to taper off tonight as winds back to
the S/SW. Though skies have been able to clear out across most of
the UP this evening, clouds are quickly filling back in from the
west with warm advection ahead of a weak Clipper that is currently
analyzed over the Dakotas. This should touch off some light snow
beginning closer to 06Z in the western UP.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 258 PM EST Wed Jan 29 2025
KMQT radar returns and visible satellite trends show the evolution
of ongoing lake effect snow over the eastern UP. Webcams have shown
occasional low visibility for the Munising area and various snowfall
reports have shown that the band over Luce County has overperformed
most QPF guidance already and continues to persist. While peak
reflectivity has fallen in these bands and coverage has fallen, the
capability for these bands to deliver low enough visibility to cause
travel hazards has prompted an extension of the Winter Weather
Advisories for the eastern UP. As ridging continues to push into the
area (the RAP analyzes a discrete 1016mb high over the Bayfield
Peninsula), the coverage and intensity of snow showers will continue
to diminish from west to east. Therefore, the advisory for Alger and
northern Schoolcraft counties has been extended to 21Z and Luce
County to 00Z tonight. Should radar returns from the CASMR radar
continue to show potent lake effect snow persisting for Luce County,
a further extension to midnight is possible, but not expected.
Overnight, a very weak round of snowfall is expected with a warm
front attached to a very weak Alberta Clipper that will arrive over
the UP later in the day. With local surface ridging still ongoing
and 500mb heights rising, even the frontal forcing will struggle to
produce much precip, with the HREF probabilities of greater than a
half tenth of an inch of QPF only about 20-40% over the west and
only around 10% in the east. As a result, even in a fluffy 20:1 snow
regime, an inch or less of snowfall is expected overnight.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 231 PM EST Wed Jan 29 2025
The overall synopsis in the extended starts off with a closed, upper
level low pressing eastward trough middle CONUS while a shortwave
drops southeastward from the Canadian Rockies. These two features
will transit the Midwest Friday before pressing into the Atlantic
Saturday. From there, mid-level ridging will extend across central
Canada southward into the middle-Mississippi River Valley ahead of
two shortwaves ejecting eastward from the Rockies. Further west,
deep troughing looks to establish itself over the Pacific Northwest.
The shortwaves will force the ridging downstream through the Upper
Great Lakes Saturday followed by the initial shortwave Saturday
night and Sunday. There is still some uncertainty in the track of
this initial wave and its subsequent surface low and warm front.
Beyond this though, guidance has come into better agreement in the
past 24 hours on the evolution of the second shortwave. This
feature, will spin up a more aggressive surface low Sunday, which
will pull a cold front through the forecast area late Sunday into
Monday as the low transits Ontario. After this system, lake effect
downwind of Lake Superior is expected Monday/Tuesday while high
pressure gradually slides eastward across Canada.
Weak, isentropically forced light snow will continue to move through
the forecast area early Thursday with dry air and clear skies
quickly building in afterwards for a majority of the day. Total
accumulations expected for this event would likely be an inch or
less. Friday, the combination of the low transiting to the south
and lingering surface troughing may support enough vertical motion
for snow showers in the western half`s lake effect snow belts;
however, snow amounts again would be light if these do materialize.
These could persist into late Friday/Saturday, perhaps expanding
into the east, but mid-level dry air and increasing subsidence would
work against notable accumulations. The next period where precip
could occur begins late Saturday into Sunday when a swath of
isentropically forced wet snow builds across the region.
Deterministic guidance suggests good agreement on the precip at this
point, but disagree on the position of the second shortwave`s low.
This appears to impact whether or not we get dry slotted Sunday, the
magnitude of warm air Sunday, and the amount of moisture available
for the cold front Sunday night/early Monday. Given the timing of
the initial wave of precip, ptype should be wet snow, but if precip
holds on into Sunday afternoon, I can`t rule out a mix of rain and
snow, or rain (NBM suggests 20-30% for rain across Menominee County
in the afternoon). Precip, if any, along the cold front Sunday night
into early Monday looks to be snow with lake effect snow showers
afterwards Monday into Tuesday. Total snowfall amounts with this
event are tough at this point given the dry slotting potential. GEFS
and EC ensemble systems both suggests high probabilities (>75%) of
widespread light system snow, but struggle to materialize any
worthwhile statistics for anything above 3 inches. Tightening
pressure gradient during the passage of these features will also
support stronger winds, particularly in the Keweenaw Sunday night and
Monday.
For temperatures in this period, a warm Thursday with daytime
temperatures climbing into the upper 30s to low 40s is expected
across the entire forecast area. These cool into the upper 20s to
low 30s for Friday and mostly 20s Saturday. As mentioned earlier,
temperatures on Sunday are a question, but it is possible another
day with widespread 30s could occur. Beyond this, temps fall back
down into the teens and 20s. Overnight lows follow a similar up and
down pattern, rotating between teens and single digits. Coldest
conditions, potentially near zero will be possible Friday night and
maybe overnight Monday/Tuesday in traditional interior cold
locations.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 612 PM EST Wed Jan 29 2025
A brief period of VFR persists this evening, but then a quick wave
of -SN will pass over the terminals overnight. IWD is expected to
remain VFR, but could (30% chance) see an hour or two of high-end
MVFR ceilings. CMX and SAW are expected (50+%) to fall to MVFR for
at least some time in the early morning hours, but all 3 sites
should return to VFR conditions by the late morning hours of
tomorrow. Winds will gradually back from the NW to the S through
this evening and tonight before beginning to veer back to the W near
the end of the TAF and eventually NW by the end of Thursday.
&&
.MARINE...
Issued at 231 PM EST Wed Jan 29 2025
Strong northwest winds will continue to weaken tonight as they shift
to southerlies. Winds at or below 20 knots are mostly expected after
midnight lake-wide. These lighter winds, more or less, remain over
the region through at least Saturday afternoon. The next waves move
through the region at that point. Current thinking is for southeast
winds to increase to near 30kts across the east half Saturday night,
then weaken Sunday before increasing again to near gales Sunday
night into Monday with the passage of a cold front and strong
pressure couplet.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
UPDATE...LC
SHORT TERM...GS
LONG TERM...JTP
AVIATION...LC
MARINE...JTP