Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/19/21
Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
512 PM CST Mon Jan 18 2021
Skies are expected to remain VFR at all TAF sites through this
forecast. Some light snow may affect the DHT TAF site Tuesday
morning, but conditions are still expected to remain VFR. North
winds will prevail at 10 to 15 knots.
.PREV DISCUSSION... /Issued 230 PM CST Mon Jan 18 2021/
SHORT TERM...Today through Tomorrow Night...
Mid-level satellite water vapor analysis shows some moisture
advecting east across the central Panhandles with high clouds
present and increasing through the day. A few returns on radar are
popping up across the far east central and west central
Panhandles, but likely most of that moisture is virga and not
reaching the ground with dewpoint spreads of 20 or more degrees
across the area.
RAP 500mb analysis shows two waves; the first off the coast of
southern Cali and the second in south central Idaho. The first
wave will remain stationary, while the second wave is expected to
dive south across the Nevada/Utah border tonight as it becomes a
stronger closed low. This will help to bring the cooler air mass
into the mid-levels, which will in return create a layer of
saturation in the dendritic growth zone. However, most of the
better low level moisture will remain to our West in New Mexico
with only a slight chance for some light snow across the very far
western Panhandles. Temperatures even further south are a bit
warmer near the surface and may likely stay light rain. With
soundings at DHT showing a fairly dry boundary layer, there is a
chance some areas in the far west may only see virga.
Accumulations at this time are expected to be less than an inch
with no major impacts.
The second wave that became a closed low will continue to push
south across southern Nevada and southern Cali tomorrow and taking
the place of the first wave off the southern Cali coast by late
tomorrow night. This upper level closed low will remain
stationary through tomorrow night with west southwesterly flow
aloft. Winds at the surface tomorrow will remain light out of the
north and temperatures will be almost 8 to 10 degrees cooler than
today as the cold air behind the front this morning starts to
filter into the Panhandles overnight tonight with little recovery
expected tomorrow. Cloudy skies will persist tomorrow through most
of the day, but begin to break by the early evening hours with a
potentially beautiful sunset.
LONG TERM...Wednesday Through Sunday Night...
Cutoff low over the Baja area will push southwest flow over the
Panhandles on Wednesday and early Thursday. Breezy southwest winds
on Wednesday will lead to temperatures in the upper 50s to lower
60s. Right now it`s looking pretty dry, however there will be some
moisture transport over the area. Most of the moisture will be at
the mid/high levels, so there will probably be some cloud cover.
This will keep the minimum RH values in the 30 to 40 percent range,
and the Fire Weather threat down. Cold front expected Thursday as
the system kicks out across the southern CONUS and becomes more of
an open wave. Right now there is some question as to whether or not
there will be any precipitation on Thursday night. Some guidance
suggests that we will have just enough moisture eject over the area
and collide with the front to bring some light rain/snow. But
several ensemble members trend the moisture to the south and NBM
continues to keep the area dry.
So with that the forecast is to be cooler on Thursday into Friday.
Thursday will be a bit tricky, as the frontal passage timing will be
highly contingent on the highs. Friday expected to be in the mid
40s to lower 50s as the front will be well through. While this is
all taking place on Thursday and Friday there will be another system
over the Pacific northwest that dives down western CA into a cutoff
low, and will take similar position to the previous system. And
while Pacific moisture will be transported across the southern
Rockies, and may reach the Panhandles, we could also see another
round of dry southwest flow. Again, breezy winds on Saturday with
temperatures rebounding into the 60s. Sunday may see the same
result, assuming the next cold front holds until Sunday night. Right
now due to this being another open wave trof, it appears that the
decent plume of moisture being drawn up from the Gulf will only clip
the far eastern Panhandles, if at all. But again, it doesn`t
currently look to be enough of a Fire Weather concern due to the
higher RH values and winds only around 20 to 25 mph. Small shifts,
or subtle changes in the storm track, or if it manages to remain a
closed low v.s. open wave, would support a better chance for
precipitation. So while there isn`t much in the forecast at this
time, there is certainly room to have pops added, down the line.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
545 PM CST Mon Jan 18 2021
VFR flying conditions will lower to MVFR at the I-35 sites late this
evening and at KDRT early in the overnight with all sites lowering
to IFR overnight to possibly LIFR early morning as SHRA develop and
become more numerous. CIGs will rise to MVFR at the I-35 sites late
morning. However, all sites will fall to IFR as a cold front moves
across the area, first at KDRT mid morning and then at the I-35 sites
mid to late afternoon. S to SE winds 5 to 12 KTs, will shift to NW at
10 to 15 KTs at KDRT mid morning, and N at 10 to 15 KTs at the I-35
sites in the afternoon. A few gusts to 25 KTs are possible in the
wake of the frontal passage. Most recent models still show some
disagreement on the timing of the frontal passage for the I-35 sites
with a couple earlier (around midday) while a few are later (closer
to early evening). Forecasts will be adjusted as trends become more
.PREV DISCUSSION... /ISSUED 246 PM CST Mon Jan 18 2021/
SHORT TERM (Tonight through Tuesday Night)...
A very moist airmass has been pouring into the region overnight and
through the morning and as of 18Z today dew points range from as
high as 60 at Kenedy to as low as the upper 30s still in Val Verde
County. RAP analysis shows a sfc low over west TX with high pressure
over the SE CONUS, and southerly flow has increased today to a
general 5-15 mph with gusts to 20-25 mph, isolated to 30 mph north.
These winds will decrease quickly with the loss of daytime heating
this evening. Low stratus has been slow to erode over central
portions of the region and have lowered forecast highs as a result
for SAT, HDO, ERV, etc where mid to upper 60s will likely be the
ceiling. Elsewhere, 70s are expected.
Tonight, low stratus will return and some areas of fog are also
possible across the Hill Country extending potentially to the I-35
corridor by Tuesday morning. This fog may be locally dense once
again. Isolated shower activity could begin to develop along and
east of I-35 by as early as 9pm tonight as the LLJ picks up, perhaps
patchy drizzle with a shallow saturated layer initially, but rain
chances will gradually increase after midnight as isentropic lift
continues to build over the region. Lows will be warm, in the upper
40s NW to near 60 SE.
Rain chances will expand south and westward during the daytime as
overrunning flow continues over a cold front slowly pushing into the
area after sunrise. There could also be some isolated thunder along
the front as CAPE increases to 300-600 J/kg, but with h5a height
rises and a decent capping inversion around 10 kft its unlikely to
be more widespread. There remains some uncertainty in frontal
timing, with high-resolution guidance suggesting a faster
progression exiting to our south by 6-7pm Tuesday. Global guidance
is slower, with the GFS now stalling the boundary across our Coastal
Plains counties in the late afternoon and evening. Leaning the
official forecast closer to the high-res solution. Regardless of
timing, a period of moderate northeasterly winds is expected behind
the front in the afternoon and evening at 10-20 mph with gusts up to
25-30 mph possible once again in some locations.
Tuesday night, especially after midnight, better chances for
appreciable rainfall amounts will shift to the west over the Winter
Garden and Rio Grande areas. These higher rain chances will also
spread northward to the southern Edwards Plateau by the end of the
short term period. In all through 12Z Wednesday, a widespread 0.25-
0.5" of rain is forecast with isolated higher totals. The best
chance for amounts in excess of 0.75" will be right along the
escarpment where orographic enhancement takes place prior to FROPA
as well as out west where the heavier rainfall rates will migrate
tomorrow night. Aside from the low visibility in fog tonight, no
hazardous weather is expected. Generally just some much needed
rainfall for those regions still in drought status.
LONG TERM (Wednesday through Monday)...
With Tuesday`s cold front still lingering around the area in
combination with upper level support, chances for rain continue on
Wednesday for much of the day. Scattered to numerous showers are
expected to concentrate across the Rio Grande and then shift to the
east-northeast to affect parts of the Hill Country and areas along
the Interstate 35, including Austin and San Antonio metro areas on
Wednesday afternoon and evening. The mid level short wave that will
help those showers to pull to the Hill Country is forecast to push
to the east and flatten through Thursday. With this scenario in
place, expect periods of dry weather early Thursday through the
afternoon hours with chances of showers concentrated across the
As Thursday evening progresses, another cold front is forecast to
push across the area on Thursday night into Friday. Chances of
showers and isolated thunderstorms are expected through the period
with activity coming to an end from west to east mid morning to mid
afternoon Friday. Some lingering showers and a thunderstorm or two
are possible across the far east Friday afternoon.
Dry conditions will not last long as the cold front pushes back
north into the area as a warm front and stays over the region over
the weekend with moist gulf moisture prevailing. The work week
starts with wet conditions with the arrival of a Pacific cold front
over South Central Texas. Weather conditions should clear out by
Highs should be above climate normal in the upper 60s to lower 70s
across the Hill Country to the mid to upper 70s elsewhere. The
exception to this pattern will be Wednesday as max temperatures only
reach the mid 50s across the Hill Country to lower and mid 60s along
and east of I-35. Lows should range from the upper 40s to lower 60s.
Storm rainfall totals are expected to range from one tenth to one
half inch across the Edwards Plateau and western Hill Country to one
half to one inch across the escarpment, northern Hill Country, and
areas along and east of Interstate 35. A few isolated spots could
get higher amounts.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 57 65 48 58 53 / 50 60 50 50 40
Austin Bergstrom Intl Airport 58 67 48 60 52 / 40 60 50 50 40
New Braunfels Muni Airport 59 69 50 62 55 / 40 50 50 60 40
Burnet Muni Airport 53 57 45 55 50 / 40 60 40 50 30
Del Rio Intl Airport 53 58 47 57 48 / 20 50 70 60 20
Georgetown Muni Airport 55 61 46 57 51 / 50 70 40 50 40
Hondo Muni Airport 58 68 50 61 52 / 30 50 60 70 30
San Marcos Muni Airport 58 69 48 60 53 / 40 60 50 50 40
La Grange - Fayette Regional 61 71 52 64 58 / 30 50 50 40 40
San Antonio Intl Airport 59 69 51 60 55 / 40 50 50 70 40
Stinson Muni Airport 60 70 51 61 55 / 30 50 50 70 40
Area Forecast Discussion
National Weather Service North Platte NE
548 PM CST Mon Jan 18 2021
.SHORT TERM...(This evening through Tuesday night)
Issued at 347 PM CST Mon Jan 18 2021
The main forecast challenges through midweek revolve around
temperatures, precipitation chances, and wind. A persistent upper
trough over the Upper Mississippi Valley with a series of surface
waves will keep conditions fairly active for the central Plains.
Some instability along with a band of mid-level instability helped
lead to snow and rain shower activity across the Sandhills today.
Even a few cloud flashes were detected as RAP mesoanalysis suggested
up to 250 j/kg MUCAPE.
This evening and tonight... Continued chc PoP of rain/snow through
03z for north central Neb as a sfc low drags a weak front through
the area. Weakening surface forcing and a brief lull in fgen at H5-7
should help the sky clear for the most part going into the overnight
hours. However, a passing PV anomaly, continued 30+ kt northerly
flow at H85, and a steepening surface pressure gradient will keep
wind speeds elevated. Despite the lack of full boundary layer
decoupling, lowered min temps a degree or so to account for modest
CAA. H85 temps should end up 4 or 5C cooler by 12z Tuesday compared
Tuesday and Tuesday night... A follow-up cool front quickly brushes
the Sandhills during the day, but forecast soundings indicate
abundance of dry air from H85-5. Some higher res guidance suggests
the potential for terrain induced showers near the Black Hills.
However, confidence is low for any of that activity to reach and
kept the forecast dry for now. Given mixed clouds/sun and weakening
temp advection during the day, stayed close to a general model blend
for max temps. Forecast ranges from upper 30s north to lower 40s
.LONG TERM...(Wednesday through Monday)
Issued at 347 PM CST Mon Jan 18 2021
For the rest of the week into next weekend, the upper trough digs
somewhat then flattens ahead of a closed low coming onto the
California shore. A lee side surface low is progged to precede the
deepening upper low Sunday into Monday, tracking somewhere in the
central or southern Plains. Discrepancies exist in the long range
guidance concerning the overall timing, placement, and intensity.
Potential exists for some impacts to western Nebraska,
particularly Saturday or Sunday, including snow. Details aren`t
exactly clear, especially with the thermal profile at play with
H85 temps approaching 0C at times. In the meantime, rapid WAA and
downsloping winds will bring a seasonably mild and dry day on
Wednesday. As westerly winds approach 30mph and humidity values
approach 25%, fire weather concerns are raised. Temps then fall
again into the 30s by Friday with the passage of a strong cold
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 543 PM CST Mon Jan 18 2021
Light rain and snow showers continue across portions of the
Sandhills moving southeast into central Nebraska. These showers
may briefly affect KVTN and KLBF terminal over the next hour or
so, briefly reducing visibility and bringing lower cigs. Breezy
northwest winds will continue to diminish this evening with winds
around 5 to 10 kts expected overnight into Tuesday morning. Winds
will increase tomorrow afternoon out of the northwest with gust
near 20 kts. Lower cigs will move into portions of northern
Nebraska including KVTN terminal with cigs approaching MVFR.
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
852 PM CST Mon Jan 18 2021
852 PM CST
A couple forecast nudges this evening. Clearing has worked in more
aggressively than initially expected, and as a result have
adjusted temperatures downward quicker and over a little larger
area. Also, and maybe a bit more of note, have pushed up the
timing of Tuesday`s light snow, with arrival time into the Chicago
metro looking more likely early Tuesday afternoon. However, it
may be off and on before a steadier period later afternoon and
early evening. That`s an aspect that is still too uncertain.
Accumulations look to be in the one half to one inch range.
GOES-16 satellite imagery has showed the back side of the clouds
moving eastward around 30 kt the past few hours, in-line with RAP
875-900 mb winds and drying. This solution indicates most of the
CWA looks to be heading for a 3-6 hour period of clear skies.
Already in northwest and north central Illinois this has resulted
in a sharp temperature drop, with a couple locations going calm
on their wind indicating a sharp inversion. With the snow cover,
this could allow for a few sites in north central Illinois to dip
into the single digits by a few degrees (could even see a
favorable location or two drop to 5 degrees). With the steepness
of the inversion and the hydrolapse, as well as just a late day
clearing regime, do still have some concern for patches of shallow
fog, especially in north central Illinois. The wind at the top of
the steepest part of the inversion (only around 400 ft) is
forecast to be 10-15 kt on the RAP and HRRR over north central
Illinois. That`s likely enough to prevent the fog from getting too
widespread or maybe even dense in those local spots. Also mid-
level clouds moving in during the pre-dawn period should help.
Looking upstream, regional radar indicates areas of snow from the
Twin Cities to eastern Nebraska. These are associated with a
short wave trough centered 600-700 mb. This is forecast to dampen
some as it approaches into Tuesday morning, stifled slightly by
some confluence in the upper levels. That said, the cold
antecedent air mass and omega with this wave should support some
-- possibly spotty -- moving into areas along/north of I-80 late
morning into the early afternoon. The 00Z guidance that is
available at the time of this writing (HRRR, RAP, NAM) all have
leaned with this quicker initial snow forcing arrival.
The stronger and deeper clipper wave is presently moving into
North Dakota and that will be on the heels of this first one. The
00Z NAM shows almost no break in forcing for snow, with light snow
continuing through early to mid evening, with maybe even a pocket
or two of moderate snow. It`s on the aggressive side of the
solution envelope right now, but felt the signal is there to
shift the favored timing up several hours. Do think snow chances
will be tapering west to east during the evening fairly quickly.
The overlap time with the evening commute, including some light
snow prior with temperatures in the 20s, does hint that there
could be some minor travel impacts on especially untreated
surfaces. But that may depend on that we can get several
consecutive hours of light snow and not an off and on nature. The
higher snow ratio signal continues to be shown, which will make
up for a low QPF event (0.02-0.07 inches) and possibly provide a
few sites over an inch of snow. The overnight shift will dig into
this much further.
314 PM CST
Through Tuesday night...
A weak upper level wave is exiting our CWA to the east after
creating flurries and areas of light snow earlier this morning
as seen in the water vapor channel. The RAP depicted this area of
snow nicely with its 700 mb vorticity, but most models`
reflectivity/PoPs did not handle the area well, with the exception
of the 18/06Z ECMWF, which was used initially for PoPs. We`ll hold
onto some additional flurry chances this afternoon across
northeast Illinois. As this wave exits, skies are starting to
clear out over most of Iowa, and this clearing may push into our
region this evening and overnight. It`s still a bit unclear just
how far east this clearing will push, with re-development on the
western flanks possible with some lingering subtle low-level warm
advection. If skies do clear, the presence of upstream dewpoint
temperatures in the teens and snow covered ground would lead to
some fairly cool low temperatures and the potential for fog. With
just a hint of wind off the deck, don`t think a widespread dense
fog threat exists, but have elected to introduce a mention of some
patchy fog near our I-39 locales. Big question mark on the low
temperatures as a result of all this as well, but it seems likely
that are typical cool spots out west could fall pretty quickly
into the lower teens tonight.
The break in clouds will be short-lived with the approach of our
next weather system Tuesday afternoon. Continued to side with the
ECMWF once again to depict this system, with strong agreement
noted among its ensemble counterparts. The deterministic GFS and
incoming early-afternoon hi-res guidance remains a bit farther
south, but the GFS ensemble paints a picture more similar to the
EPS/ECMWF. This clipper will initially create snow flurries in
mid-afternoon Tuesday, possibly transitioning to some bonafide
light snow during the late afternoon, with more widespread light
activity developing in the early evening as the column becomes
more saturated up to 700 mb. Cold temperatures aloft and forcing
through the DGZ should support higher ratio snow. Current forecast
depicts a broad area of dusting to 1 inch amounts at this time.
This clipper will move through quickly, with snow ending early
morning Wednesday, and clouds expected to also depart quickly west
to east, leading to possible areas of freezing fog, especially
for the western counties. With clouds in place most of the night,
temperatures will not be as low as Tuesday morning, but cold air
advection behind the clipper will still create conditions for lows
in the teens throughout the CWA Wednesday morning.
Wednesday through Monday...
212 PM...Main forecast concerns include...
Strong/gusty southwesterly winds Wednesday afternoon/evening.
A period of colder temps Thursday night through Saturday morning.
An unsettled pattern Sunday/Monday with a wintry mix possible.
A ridge of high pressure will be shifting east of the area
Wednesday morning as strong low pressure moves across Ontario into
Wednesday night. The gradient will quickly tighten by Wednesday
afternoon with southwesterly winds possibly gusting into the 30-35
mph range by late afternoon and these stronger winds may continue
into early/mid evening. High temps have the potential to warm well
into the 30s but how warm temps reach is somewhat uncertain given
lows likely starting in the teens across much of the area. Temps
may hold steady in the lower 30s Wednesday night with highs on
Thursday likely back into the mid/upper 30s with perhaps some
areas tagging 40.
A strong cold front is expected to move across the area Thursday
evening bringing with it quite a bit more colder air. Lows by
Friday morning will likely be in the teens across much of the
area. Low confidence for how much highs will rebound on Friday,
though 20s is possible. Then high pressure settles across the area
Friday night with likely clear skies to start, perhaps some
increase in clouds Saturday morning. This should allow temps to
tank Friday evening and single digits seem on track for much of
north central and northwest IL. Have maintained the previous
forecast low temps for Friday night/Saturday morning but these are
warmer then the newest mex guidance temps. The light winds should
limit wind chills which based on current trends reach the -5 to
+5 range by Saturday morning.
There remains quite a bit of uncertainty regarding a storm system
that may affect the area Sunday into Monday next week but there
are some trends emerging that have been somewhat consistent run to
run and in some cases...model to model. A wave appears to move out
of the Rockies Saturday/Saturday night reaching the western Great
Lakes by Sunday morning. This is seen on all of the models with a
band of most likely snow spreading across the region. The local
area may stay on the south end of this wave`s precipitation.
Despite these trends, confidence remains low but an accumulating
snow during this time period will certainly need to be watched.
Enough warm air looks to arrive on Sunday that if any precip is
ongoing, it would likely transition to some kind of wintry mix. By
this time period, current model differences make for a challenging
forecast, which may continue to remain challenging given the
proximity to a wintry mix. But the trend of a surface low
developing across the southern Plains and lifting northeast to the
southern Great Lakes or Ohio Valley continues. A further south
track would increase the odds of accumulating snow and/or a wintry
mix while a further north track would allow for more liquid rain
across the area but with precipitable water values approaching
0.75 to 1 inch in the warm sector, a warmer solution could lead
to periods of moderate/heavy rain. cms
For the 00Z TAFs...
MVFR clouds will clear from west to east across northern Illinois
this evening, leading to VFR conditions through Tuesday morning.
Meanwhile, winds will remain between WSW and WNW at around 10
Two compact mid-level waves in the northern Plains early this
evening will track southeast into the region late Tuesday morning
into mid-evening. The main message is that there is a high
likelihood of -SN with at least MVFR visibility for several hours
during this time, but it remains unclear which of these systems
will be the dominant precipitation producer. Model and upstream
observation trends are beginning to suggest that the first wave
during the early to mid afternoon may bring the best chance of
snow versus the second wave during the late afternoon and early
evening. Until those trends become more established this evening,
will main consistency with highlighting the second wave with
prevailing -SN and introducing a PROB30 for the first wave.
However, if both systems are active, a prolonged period of -SN
with MVFR to VFR visibility would be expected.
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Area Forecast Discussion
National Weather Service Pueblo CO
312 PM MST Mon Jan 18 2021
Issued at 311 PM MST Mon Jan 18 2021
Did a quick update to increase pops for the snow showers
developing in and around the Pikes Peak region. /Hodanish
.SHORT TERM...(This evening through Tuesday)
Issued at 246 PM MST Mon Jan 18 2021
...Beneficial snow for the southern higher elevation areas of the
At 2 pm, lots of clouds were noted over the region as disturbance
over the Salt Lake city region drops south-southwest. Flow aloft is
becoming more westerly and tightening, and this is seen in the
higher level clouds racing west to east across the fcst area. Radars
across the state have remained pretty much echo-free but this will
not last. NW`erly low level wind flow earlier today was slowly
transitioning to an upslope flow. Temps at 2 pm were generally in
the 30s and 40s across the plains, with 40s in the San Luis Valley.
Higher terrain areas were in single digits at mtn tops to 30s lower
rest of Today into Tonight...
Snow is expected to break out along the along the mtns/plains
interface late this afternoon and expand both to the east and west
as the evening progresses. Believe snow will not make it too far
east...mainly staying around the I-25 corridor, however snow will
builds south and westward as the evening progresses, moving into the
San Luis valley (SLV) this evening and increasing across the greater
San Juan region tonight. Guidance is trending hotter with snow
amounts across all of the southern mtns and San Juans, and the SLV.
For this reason. have bumped up snowfall amounts somewhat and have
upgraded the southern Sangres and the higher San Juans to a Winter
Storm Warning. I should note that the latest runs of the HRRR are
showing more snow than what I have currently in the NDFD, showing 2
feet or more across the southern mtns. The reason for this heavier
snowfall amounts from the HRRR may be due to a favorable
thermodynamic profile as quite a bit of the atmosphere is saturated
in the favorable dendritic growth zone. this is also hinted by other
guidance. Will let evening crew know about this and if trends
continue, they may need to bump up amounts across the southern half
of the fcst area, and upgrade associated highlights.
Most of the heavier snow will occur during the predawn hours of
Tuesday (midnight to 6 am-ish)
Confidence still remains rather high that most of the plains will
not see much with this storm as most of the forcings remains to far
to the west to bring any snowfall to the plains well east of the I-
25 corridor. Also C mtns and Pikes Peak will see generally light
amounts of snow (2-4 mtns...inch or two lower elevations/valleys).
Min temps tonight will be in the L/M20s over the plains with tens
SLV...and single digits mtns.
Snow will be lingering over the I-25 corridor region generally south
of Pueblo after sunrise tomorrow with some moderate to locally heavy
snow continuing in the southern Sangres, SE sxns of the SLV and the
San Juans. By afternoon the snow should primarily be in the San
It will be cool tomorrow. 30s and L40s will occur over the plains
with coolest temps on the divides and warmest temps over the far
eastern plains. SLV should reach highs around freezing. teens and
20s mtns. We will see some sun over the I-25 corridor by afternoon.
Overall, I do not expect much in the way with wind with this weather
system winter weather impacts will be lower than normal. Travel will
be tricky along the 160 corridor and SLV, and the I-25 corridor
south of Pueblo to NM. The (very) good news with this is areas which
need beneficial precip are going to get it. Areas south of US-50 and
West of I-25 should do rather well with this winter precipitation
.LONG TERM...(Tuesday night through Monday)
Issued at 246 PM MST Mon Jan 18 2021
Tuesday night-Thursday night...Generally weak west to southwest flow
aloft across the region on Tuesday becomes more westerly through the
day Wednesday, as more energy digs across the Upper Midwest. Another
eastern Pacific system starts to move onshore across the Pacific
Northwest Coast on Wednesday and is progged to dig across the West
Coast through the day Thursday, helping to kick out the weakening
Desert Southwest upper trough across the region Thursday and
Thursday night within the moderate west to southwest flow aloft
across the Rockies. The increasing westerly flow aloft develops lee
troughing across the Plains, with breezy westerly gap winds expected
across the lower eastern slopes both Tuesday night and Wednesday
night, keeping low temperatures at or above seasonal levels,
especially in the "banana belt". Valley locales will see the
coolest temperatures, especially the San Luis Valley, where expected
snowcover will allow for temperatures to tank into the single
digits. With the breezy westerly winds, highs in Wednesday will warm
into the 50s to lower 60s across the plains, with highs mainly in
the 30s and 40 across the higher terrain. Temperatures on Thursday
will be slightly cooler across the area, with a few possible showers
across the higher terrain of the ContDvd Thursday afternoon and
evening, as the weak embedded disturbance moves across the region.
Friday-Saturday...Models continue to indicate moderate to strong
west to southwest flow aloft continuing across region, as the West
Coast system slowly digs into the Desert Southwest. Models also
indicate increasing moisture within the flow aloft moving into the
Rockies, leading to good chances of precipitation for the higher
terrain, especially along and west of the ContDvd where could see
possible winter weather highlights through this period. Further
east, breezy downslope winds will lead to dry conditions, with
enhanced fire danger across plains, especially on Saturday. At and
above seasonal temperatures continue through this period, warmest
across the plains.
Sunday-Monday...Models indicating differences in timing and location
of the Desert Southwest system ejecting across the Rockies through
early next week. The GFS is quicker with the system moving across
the Rockies through the day Sunday, as more eastern Pacific energy
digs across the Great Basin Sunday night and Monday, whereas the EC
hangs the trough out across the Desert Southwest on Sunday with the
Pacific Northwest system kicking the system out across the southern
Rockies on Monday. With the model differences, have followed the
blended model solution which keeps chance and likely pops across the
higher terrain on Sunday and Monday, with slight pops spreading east
across the plains Sunday and Sunday night. Temperatures look to
remain at or slightly above seasonal levels through this period.
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 246 PM MST Mon Jan 18 2021
A pacific weather system will affect the region, especially this
evening and into tomorrow morning. Accumulating snow will be likely
at KALS, and some light accums may occur at KPUB and KCOS (~ 1
inch). Low cigs will be possible at all taf sites, especially KALS.
Winds will generally be light with this weather system. Conditions
will improve at KCOS by mid morning and mid to late morning at KPUB.
Conditions may not improve at KALS until the mid to late afternoon.
Winter Weather Advisory from 8 PM this evening to 2 PM MST
Tuesday for COZ067-069>071.
Winter Storm Warning from 8 PM this evening to 5 PM MST Tuesday
Winter Weather Advisory until 2 PM MST Tuesday for COZ072-073-
Winter Storm Warning until 2 PM MST Tuesday for COZ074-075.