co discuss
Office: BOU
FXUS65 KBOU 081119
AFDBOU
Area Forecast Discussion
National Weather Service Denver/Boulder CO
519 AM MDT Wed May 8 2024
.KEY MESSAGES...
- Freeze warning for the Palmer Divide...and a Frost Advisory most
of the plains and I-25 corridor early this morning.
- Continued light snowfall in the mountains with some blowing snow
over the higher passes.
- Cool and unsettled weather Thursday through Friday.
- Warming Saturday through Tuesday with late day showers and
limited thunderstorms.
&&
.SHORT TERM /Through tonight/...
Issued at 346 AM MDT Wed May 8 2024
The upper level low will be over the central High Plains today with
a continuation of WNW flow aloft. Overall, the flow will gradually
decrease thru the day so wind speeds won't be as high as the last
few days. However, for this morning, there will be at least a minor
mtn wave which will combine with cross-barrier flow in the 35-40 kt
range to produce of period of gusty winds in and near the foothills.
At this point, gusts should stay below 60 mph. By midday, winds
should gradually decrease as mtn wave breaks down and cross-
barrier flow decreases. In the mtns, cross-sections still show
enough moisture combined with favorable orographics to produce
periods of light snow mainly north of I-70. Across the plains, it
will be dry, although with improving lapse rates by aftn can't
rule out a slight chc of showers near the WY-NE border area. As
far as highs, readings this aftn will be in the upper 50s to lower
60s over nern CO.
For tonight, the upper level low will gradually elongate and split
apart as one piece of energy moves WSW into wrn CO by 12z Thu.
Meanwhile, a cold front will move across nern CO overnight with
upslope flow developing. May see a gradual increase in shower
development in the nrn foothills and nrn portions of the I-25
Corridor after midnight which will spread southward into the srn
foothills and the rest of the I-25 Corridor by 12z Thu. In the
mtns, best chc of additional snow will be on east facing slopes
overnight.
Finally, as far as frost/freeze winds have been stg enough to keep
temps well above freezing in most areas. However, near sunrise may
still see an hour or two where readings may drop to near freezing,
so will keep highlights in place.
&&
.LONG TERM /Thursday through Tuesday/...
Issued at 306 AM MDT Wed May 8 2024
Models have an east-west oriented upper trough across the CWA on
Thursday. By late Thursday night, an upper closed low is over the
Great Basin and Utah with weak troughing over us. This pattern
stays that way all day Friday into the evening, then the upper
circulation moves a bit east and is over southern Utah by 12Z
Saturday morning. There is weak downward vertical velocity over
much of the CWA concerning the synoptic scale energy Thursday and
Thursday night. Weak upward vertical velocity is progged Friday
afternoon through Friday night. The low level pressure and wind
fields have upslope in place for the plains Thursday and Thursday
evening. Normal diurnal wind patterns should be in place Friday
and Friday night.
Looking at moisture, it is pretty deep on Thursday, especially over
the western half of the forecast area. Moisture stays pretty deep
over the western half of the CWA Thursday night well into Friday
night. The eastern CWA is fairly moist Thursday into Friday mid
day. The QPF fields show limited measurable precipitation for much
of the CWA Thursday, with just the far east to stay mostly dry.
Precipitation is progged over the alpine areas through Thursday
night, Friday and most of Friday night. There could be some snow
mixed in over the plains above 5,500 feet with the heavier
precipitation areas Thursday. Expected snowfall amounts in the high
country do not look significant through Friday night.
Looking at temperatures, Thursday still looks to be the coolest day,
with highs up to 20 F below seasonal normals over the plains. Friday
warms up 3-6 C with most of the plains to make it into the lower
60s F.
For the later days, Saturday through Tuesday, models continue to
show the pinched off upper closed low to move across Utah and get
into Colorado Saturday night. Upper ridging gets into our state by
Sunday night. There is weak northwesterly flow aloft on Monday and
weak to moderate zonal flow aloft on Tuesday. Most of the models
point to late day convection each day with the best chance of
precipitation to be over the mountains and foothills. The
insatiability is not great, so the thunderstorm coverage will be
minor. Temperatures warm slowly each day with readings to be a bit
above seasonal normals Sunday. Monday and Tuesday.
&&
.AVIATION /12Z TAFS through 12Z Thursday/...
Issued at 514 AM MDT Wed May 8 2024
Once again winds have remained gusty overnight from the west.
However, they have become more WSW in the last hour. By 15z,
they should go back to more WNW with gusts up to 25 mph thru
20z. After 20Z, they will go more NW but decrease in speed.
By 01z, expect a north direction which will switch more to
the NE by 03z. Overnight they will become SE by 07z. VFR
conditions for today but will see ceilings drop to around 9000
ft early this evening. Late tonight, will likely see MVFR
ceilings by 12z Thu.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM MDT this morning for COZ038>040-
042>047-049.
Freeze Warning until 8 AM MDT this morning for COZ041.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
Office: PUB
FXUS65 KPUB 081123
AFDPUB
Area Forecast Discussion
National Weather Service Pueblo CO
523 AM MDT Wed May 8 2024
.KEY MESSAGES...
- Near and below freezing temperatures are expected for El Paso
County this morning.
- Critical fire weather conditions are expected over the San Luis
Valley and portions of the southern plains today.
- A trend towards cooler, wetter weather begins tomorrow, and
looks to persist through the weekend. This will include
periods of moderate to occasionally heavy snowfall over
portions of the high country.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 342 AM MDT Wed May 8 2024
Currently..
The low continues to sit off to our north, sending cooler air and
the jet southward over our region. Satellite imagery shows continued
cloud cover over the high country, while observations show that
light snow showers are still ongoing over portions of Lake and
Chaffee counties. Temperatures are still in the 40s and even some
low 50s over southern El Paso County thanks to continued west winds
in excess of 30 mph as of 2am. If winds remain elevated, frost
chances will become more and more unlikely this morning for southern
El Paso. That said, northern El Paso County is already showing signs
of weakening winds and temperatures approaching freezing. Just on
the other side of the Palmer, Monument Hill hit 32 degrees at
1:35am. Less than 30 miles away at Fort Carson, the temperature is
30 degrees warmer this hour at 52 degrees.
Rest of Today and Tonight..
Expecting freezing and near freezing temperatures in El Paso County
to warm quickly this morning under mostly sunny skies and breezy
west-northwesterly winds that will prevail across our mountain
adjacent plains. Models bring a cold front through later this
afternoon and this evening, which will bring with it northerly
and eventually easterly winds. This setup has made for a very
tricky fire weather forecast, though it does look likely that
we'll see at least a few hours of critical fire weather
conditions for the San Luis Valley, Otero, and eastern Las
Animas county before the northerly winds move in. This front
will also keep today's temperatures cooler, with highs only
reaching into the 60s for most plains and mountain valley
locations. Apart from freezing temps early this morning and
critical fire weather later this morning, mostly dry and quiet
weather is expected for the remainder of today and into the
overnight hours. Overnight lows tonight and into tomorrow
morning will be a few degrees cooler than normal, but still
warmer than this morning.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 342 AM MDT Wed May 8 2024
Thursday and Friday..
Models bring the upper low westward and into the Great Basin region
by Thursday. Behind the cold front, easterly winds and upslope will
eventually setup for Thursday across our mountain adjacent plains.
This will make for a much cooler and cloudier day for most
locations, though many of us will also see chances for rain and snow
as well, especially for the high country. Models bring the low
southward into northern Arizona by Thursday afternoon, which will
increase snow chances even more for our southern mountains. Models
have trended a bit higher with QPF amounts this morning and have
brought this low a bit further south as well. If this trend
continues, we could end up needing winter highlights over our
southern mountains for the Thursday into Friday timeframe.
Highest amounts look to be over the San Juans, Sangres, and
Wets, where 12 inches or so of new snow will be possible during
that timeframe. Elsewhere, rain, snow and weak thunderstorm
activity will be possible as well, especially over and near the
higher terrain for both Thursday and Friday. Daytime highs look
to be in the 60s for both days with mostly cloudy skies.
Saturday Onwards..
Forecast confidence decreases rapidly as we get into this weekend.
Models diverge on the trajectory of the low as it tries to push out
of the Great Basin. The GFS ejects the system quickly with drier
weather returning by Sunday with another system poised to drop in
from the northwest by Wednesday. Overall, NBM shows that temperatures
will remain mild through the weekend with a return to 80 degree
highs by Tuesday for the plains. Models show daily showers and
thunderstorms over the mountains through the remainder of the
extended.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 342 AM MDT Wed May 8 2024
Aviation..
VFR conditions are expected at KALS, KCOS, and KPUB through 24
hours. Winds at KCOS and KPUB will be gusty out of the northwest
this morning at KCOS and KPUB, with gusts to 25kt at KCOS and gusts
to 30kt at KPUB until 17Z. Winds at KALS will remain westerly today,
KCOS will turn northerly, and KPUB will turn east-northeasterly,
with speeds of 10-15 knots. Mid-level clouds will start to build in
across all three TAF sites near the end of this forecast period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM this morning to 7 PM MDT this
evening for COZ224-232-233.
Freeze Warning until 8 AM MDT this morning for COZ084.
Frost Advisory until 8 AM MDT this morning for COZ085.
&&
$$
SHORT TERM...EHR
LONG TERM...EHR
AVIATION...EHR
Office: GJT
FXUS65 KGJT 081356
AFDGJT
Area Forecast Discussion
National Weather Service Grand Junction CO
756 AM MDT Wed May 8 2024
.KEY MESSAGES...
- Sub-freezing temperatures for the lower valleys where
vegetation is susceptible to damage is forecast early this
morning. Other areas may see frosty conditions.
- Cool and unsettled weather will linger through the remainder
of the week. Persistent snow over the northern mountains will
bring some accumulations to the higher elevations today before
the threat shifts to the south to end out the week.
&&
.UPDATE...
Issued at 754 AM MDT Wed May 8 2024
Temperatures have reached or pushed above freezing in most areas
so the warning has been cancelled. Additional warnings may be
needed tonight again near Rifle and the North Fork/Unco Valleys
so stay tuned.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 406 AM MDT Wed May 8 2024
Cold air continued to filter southward across the forecast area
early this morning as the closed low pressure system remained over
the northern High Plains early this morning. Clearing was late
in coming for a significant portion of the areas where Freeze
Warnings were in place which has buoyed temperatures thus far.
In addition, the surface pressure gradient has proven strong
enough to keep winds moving at KCNY, KBDG, KGJT and KMTJ which
has also helped keep temperatures above freezing so far. That
said, winds have diminished at KRIL and temperatures there were
just above freezing. There's a good chance that winds will
continue to keep cold surface inversions from forming which
should be good news for local growers.
The Plains low drifts slowly southward today before turning east
late. As this occurs, the westward flowing jet in the northern
quadrant of the low causes mid-level heights to fall over the
Great Basin resulting in an elongated area of low pressure over
the region. Moisture will linger over the northern half of the
forecast area as flow aloft, though weaker, continues to advect
moisture southward. Dynamic forcing will be limited, but the
cold pool at 500 mb creates sufficient instability for mainly
afternoon showers, mainly over the northern mountains and
portions of the central Colorado mountains. Snow accumulations
will be light and fairly localized. Elsewhere, expect partly to
mostly sunny skies and dry weather. Highs are expected to
continue to anomalously cool with most locations 10 to 15
degrees cooler than normal.
The westward flowing jet north of the Plains low turns south
over the western Great Basin tonight causing a low to close off
over southern Utah early Thursday morning. Jet divergence,
instability and orographics will keep light showers going along
the northern border of the forecast area tonight. However, by
Thursday afternoon the focus shifts to the southern half of the
forecast area as difluent flow and jet divergence develops east
of the low west of the Four Corners. However, enough residual
moisture and instability will remain to fuel numerous showers
and a few thunderstorms over the mountains and high valleys
Thursday afternoon. Despite increased clouds and showers,
temperatures will moderate, though highs are still expected to
peak about 5 degrees below normal.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 406 AM MDT Wed May 8 2024
A low will become cut off from the main upper level flow and
continue to spin over the Great Basin through at least Friday night
as a Rex Block forms over the west. This will keep moisture
circulating around the low with easterly upslope flow into the San
Juans and Divide mountains. The higher elevations of the San Juans
look to be the most favored for some snow accumulations along with
the spine of the Central Divide through Friday night. Temperatures
throughout this period also look to be warming as well despite the
unsettled conditions which would increase available moisture. Lapse
rates will steepen and instability present. Given day time heating,
this should result in scattered to widespread showers and
thunderstorms, favoring the high terrain during the afternoon with
some drift off the terrain into adjacent valleys from time to time.
Even though these blocking patterns have a tendency to persist, the
models are showing some signals of this Rex Block breaking down by
Saturday with the cut off low finally moving eastward into the
Plains. Models seem to be in better agreement now than they were a
few runs ago. This may be due to more shortwave energy moving across
southern Canada and making its way into the northern High Plains and
eventually northern Rockies by early next week.
So, conditions will remain unsettled through Saturday with some
afternoon storms favoring the high terrain as we transition from the
unsettled weather with the cut off low over the region to a drier
northwest flow as high pressure tries to build in from the west by
Sunday. Additional shortwaves try to drop in from the northern
Rockies into our CWA early next week, resulting in afternoon
convection mainly over the high terrain of western Colorado. High
temperatures during this period will be around 5 degrees below
normal Friday and Saturday, warming up towards near to slightly
above normal by Sunday as the low exits, and return to 5 to 10
degrees above normal by early next week. Even though most lower
elevations will return to drier and warmer conditions Sunday through
early next week, showers and thunderstorms will be around each day
but mostly favor mountains and high valleys. It should start to feel
more like a warm Spring time convection regime.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 556 AM MDT Wed May 8 2024
Expect quiet weather at eastern Utah and western Colorado TAF
sites. VFR conditions and light winds will be the rule. However,
ceilings below ILS breakpoints will an issue for KEGE and KASE
off and on for much of the day.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
UPDATE...15
SHORT TERM...NL
LONG TERM...MDA
AVIATION...NL
