Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/26/23
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
304 PM PDT Tue Apr 25 2023
.SYNOPSIS...Sunny and hot conditions will continue to build through
midweek. A shallow marine layer along the coast with weakening
onshore wind will most likely allow even coastal locations to warm
near 70 midweek.
&&
.DISCUSSION...Strong ridging has begun to build over the area,
brining clear skies throughout the interior with highs in the mid
80s. A thin marine quickly eroded along the coast this morning under
strong solar heating. Another weak and compressed marine layer is
likely tonight with patchy coastal fog.
Temperatures will continue to warm through mid week. Many areas
could reach above 90 for the first time since October. NBM shows a
70 to 90% chance of southern Lake and Mendocino Counties in addition
to the Trinity River Valley reaching 90 either Wednesday or
Thursday. Around Ukiah, there is a 10 to 20% chance of temperatures
breaking 95, which would easily surpass the stations daily
temperature record. High pressure will also shunt stronger north
winds offshore, decreasing the strength of sea breezes and flow of
moisture inland. This will allow interior RH value to drop below 20
percent while also weakening the coastal marine layer. Midweek, any
marine layer will be shallow under a compressed marine inversion and
short lived each morning. At the same time, weakened sea breeze will
allow even coastal locations to reach above 70, NBM shows an 80 90%
chance of such temperatures around Humboldt Bay.
There is currently no rain in the forecast. Essentially all cluster
ensemble members show ridging continuing though slightly weakening
into the weekend. There is wide uncertainty beyond that. Essentially
all model ensemble members now show a cutoff low off the coast of
California by early next week. No matter the scenario, this would
bring cooler and more unstable weather to the area. 70% of model
ensemble member show the system mostly dry while the other 30% show
0.5 to 1.0 inches of rain. There is a slight chance of interior
thunderstorms early next weak, though current model soundings
resolve a strong mid level cap that would inhibit significant
storm development. /JHW
&&
.AVIATION...After some morning low clouds and patchy fog along the
North Coast, skies have become mostly clear this afternoon. Expect
some more moisture pooling along portions of the North Coast
overnight tonight, with low clouds potentially extending inland up
the Eel River Delta once again. The latest HRRR guidance suggests
that the low clouds won`t be as expansive as last night, but have
still included low ceilings and reduced visibilities around
daybreak. Winds will be mostly light. As winds diminish overnight,
coastal eddies and flow reversals will become more prevalent, and
this may keep what clouds that do form a bit more persistent near
and S of the eddies Wednesday morning. /SEC
&&
.MARINE...Gusty northerly winds will gradually shift a bit farther
offshore in the short term. Northerly winds will continue to weaken
late this week, with near shore eddies and flow reversals becoming
more likely. No changes were made to the ongoing advisories, and
only minimal changes were made to wind and sea grids. /SEC
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 9 AM PDT Wednesday for PZZ450.
Small Craft Advisory until 9 PM PDT this evening for PZZ455.
Small Craft Advisory until noon PDT Thursday for PZZ470.
Small Craft Advisory until 9 PM PDT Wednesday for PZZ475.
&&
$$
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For forecast zone information
see the forecast zone map online:
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Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
926 PM CDT Tue Apr 25 2023
...New UPDATE...
.UPDATE...
Issued at 918 PM CDT Tue Apr 25 2023
Deeper convection mid evening has shifted east of the area with the
weak mid level impulse. Isolated, low topped showers remain near the
escarpment from Williamson County south into far northern Bexar
County. Upstream convection is expected to weaken and dissipate
before reaching the area, per latest HRRR runs, as convective
inhibition re-strengthens over the area late this evening and
overnight. Any addition precipitation overnight will likely remain
shallow, beneath the cap, in the form of weak showers and possible
patchy drizzle early in the morning. We have removed mention of
severe storms for tonight.
&&
.SHORT TERM...
(Tonight through Wednesday night)
Issued at 131 PM CDT Tue Apr 25 2023
Synopsis/Mesoanalysis: Early afternoon observations show a diffuse
warm front extending northwest to southeast from the Altus, OK
vicinity through the DFW Metroplex and ultimately just east of
Houston. Temperatures range from the low 60s to upper 70s across the
warm sector, depending on the amount of cloud coverage present
locally. Persistent low overcast has held temperatures in the low to
mid 60s across our Hill Country and I-35 zones, while breaks in the
deck have allowed temperatures to climb into the mid to upper 70s in
the Coastal Plains. A dryline is attempting to organize to our
northwest, with 18Z surface obs showing the boundary sharpening from
the Lower Trans Pecos northwest toward the New Mexico Front Range.
The boundary will likely push east-northeast into portions of the
Edwards Plateau as it continues to sharpen over the next several
hours. GOES water vapor imagery shows a series of subtle
perturbations across northern Mexico, the first of which is
approaching the Rio Grande as it exits from Coahuila. The
combination of the aforementioned surface boundaries and approaching
mid-level impulse will support conditional chances of thunderstorms
through the remainder of the afternoon and early evening hours
today. Some of these storms could be severe. An upper low --
currently evident along the CO-UT border -- will shift southeast
into the Southern Plains through Wednesday afternoon. Surface
cyclogenesis will occur over the TX Panhandle as this occurs. The
resultant surface low is forecast to track due east along/south of
the Red River through Wednesday evening, pushing a weak cold front
through the area moving into early Thursday morning. Additional
storms are expected along the advancing front, with additional
severe weather possible.
This Afternoon & Evening: Thunderstorm development remains possible
as the Coahuila impulse pushes across the region. Latest high-res
guidance shows areas east of I-35 being favored for this activity,
suggesting that the light WAA/moisture advection showers ongoing
across the Coastal Plains will deepen into organized cells/clusters.
Whether this occurs will be highly dependent on low level
moistening/WAA and lift from the approaching impulse removing what
remains of the cap. Latest soundings sampled at Austin Bergstrom and
San Antonio Intl show a stout inversion in the 850-700 mb layer,
with several hundred J/kg of MLCIN remaining as of 230 PM CDT. The
Corpus Christi ACARS, which is likely a bit more representative of
the upstream environment of potential thunderstorm activity in our
area, shows a slightly weaker cap within the same layer. It`s thus
possible that continued heating/moistening could erode the cap over
this portion of the area, supporting scattered thunderstorm
development. An isolated storm is also possible over our Hill
Country zones in connection to the surging dryline discussed in the
synopsis, though most guidance points to any development staying to
our north. Large hail and damaging winds would be the main concerns
in any of these storms, though an isolated tornado can`t be
completely ruled out. Have a way to receive watch and warning
information over the next several hours across these portions of
South-Central Texas.
Tonight: Some patchy fog/drizzle is possible primarily along the
Balcones Escarpment during the predawn hours. Widespread dense fog
isn`t expected, though visibilities could drop to and below 1 mile
in isolated locations across Hill Country and the Southern Edwards
Plateau. Slow down, use low beam headlights, and allow for extra
following distance if encountering one of these spots while driving.
Thursday Evening & Night: Storm chances will increase as the cold
front discussed above enters the area. Expect the majority of the
potential to be confined to the overnight period, although an
isolated storm can`t be completely ruled out earlier in the evening
along a prefrontal trough axis positioned over Hill Country and the
southern Edwards Plateau. Severe weather will be possible in this
activity, with large hail and damaging winds once more being the
primary concerns. SPC continues a marginal (level 1/5) risk for
severe thunderstorms outside of the Rio Grande in light of this
potential, with a small portion of Hill Country and the I-35
Corridor being included in a slight (level 2/5) risk. Widespread
flooding is not a concern, though storms could produce brief heavy
downpours. This could lead to brief ponding of water & rises at low
water crossings in areas seeing multiple rounds of activity.
&&
.LONG TERM...
(Thursday through Tuesday)
Issued at 131 PM CDT Tue Apr 25 2023
A cold front will be through our area by start of the long term
period Thursday and some storms may linger until around noon.
Northerly winds behind the front will bring drier air ending any rain
chances. Thursday night the winds will switch back around to the
south or southeast returning warm, moist air to the region. Another
cold front will move through the area Friday night. Models are
getting a bit more aggressive with this system. They show a surge of
PW with strong instability and vertical wind shear. POPs have
increased slightly from the previous forecast. The ingredients also
look to be there for strong to severe thunderstorms with locally
heavy rain. We will see if this trend continues as we get closer.
Winds will be northerly again Saturday bringing dry weather for the
weekend. Temperatures will be cooler with below normal with lows in
the 40s and 50s and highs in the 70s Saturday and 80s Sunday. Dry
weather will continue through the end of the period with temperatures
warming a few degrees.
&&
.AVIATION...
(00Z TAFS)
Issued at 636 PM CDT Tue Apr 25 2023
Short term concern is convection that has developed early this
evening. TSRA should impact AUS now through 01Z. Isolated SHRAs to
the southwest, near SAT, are having trouble deepening. We anticipate
activity to gradually shift northeast through the evening, and weaken
and dissipate after 03Z. MVFR ceilings are forecast to re-develop
02Z-05Z across the Hill Country and along and east of I-35 then
expand toward the Rio Grande toward 06Z. A lowering into IFR is
expected overnight and into Tuesday morning, with a pocket of LIFR
ceilings and -DZ/BR possible near the escarpment between SAT-AUS.
Ceilings are expected to gradually improve 15Z-19Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 65 83 62 79 / 30 30 70 30
Austin Bergstrom Intl Airport 64 81 61 78 / 30 30 60 30
New Braunfels Muni Airport 65 84 62 80 / 30 20 50 40
Burnet Muni Airport 63 81 58 76 / 20 30 70 30
Del Rio Intl Airport 67 89 62 85 / 0 10 60 20
Georgetown Muni Airport 63 81 59 76 / 30 30 70 30
Hondo Muni Airport 67 84 62 81 / 10 10 60 30
San Marcos Muni Airport 65 82 62 78 / 30 20 60 40
La Grange - Fayette Regional 65 81 64 76 / 40 20 50 40
San Antonio Intl Airport 66 83 64 81 / 20 20 60 40
Stinson Muni Airport 67 85 65 82 / 20 20 50 40
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...Quigley
Long-Term...05
Aviation...76
Area Forecast Discussion
National Weather Service Goodland KS
943 PM MDT Tue Apr 25 2023
.UPDATE...
Issued at 851 PM MDT Tue Apr 25 2023
Have continued to trim QPF especially for north of Highway 40 as
dry air aloft seen on water vapor imagery and RAP soundings have
allowed drizzle to be the primary factor so far this evening.
Soundings do show the dry air saturating throughout the night. As
result have adjusted pops to show this trend. One of the more
impressive looking areas of rainfall is developing in the
Colby/Oakley area currently, which suggests to me that the dry air
is starting to saturate across the area. Current thinking now is
rainfall ranging from 0.06 inches in McCook to 1.36 inches in
Tribune. The main low is currently in SW Colorado/NW New Mexico
and is forecasted to move across northern New Mexico. Guidance
does show a sharp precipitation gradient especially along
Interstate 70, any slight wobble south with the low may further
lower forecasted rainfall amounts. As for high temperatures for
Wednesday, I upped the temperatures a few degrees along and north
of I-70 due to relatively quicker exit of rainfall and stratus.
&&
.SHORT TERM...(This afternoon through Wednesday)
Issued at 1159 AM MDT Tue Apr 25 2023
18Z Water vapor imagery and RAP analysis indicates strong H5
circulation approaching the Four Corners. At the surface
widespread southeasterly flow was in place as low pressure
continued to develop over the Rockies.
Most pressing concern will be how much, and where, precipitation
will fall through tomorrow. Initial wave of precipitation in area
of warm air advection has not lived up to initial expectations,
with only organized widespread area of precipitation occurring
across eastern Colorado. Weak subsidence/short wave ridging has
likely inhibited much of today`s rainfall as forcing not able to
overcome inversion due to aforementioned ridge. Expect scattered
showers to continue through the day, but think overall amounts
from today`s precipitation will be light.
Four corners system will continue to move to the southeast tonight
and into the Texas panhandle on Wednesday. This track is more
southerly than previously expected and with isentropic fields
indicating a sharp turn to more downward motion I expect a pretty
sharp northern gradient to precipitation. Based on latest data,
expect bulk of precipitation to fall south of a Flagler to Quinter
line. In this area looks like widespread 0.5 to 1.25 inches of
precipitation can be expected, with amounts trailing off pretty
quickly to the north of that line. Most of the area will see rain
overnight and into tomorrow, but most significant amounts will be
confined to the south.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 137 PM MDT Tue Apr 25 2023
00Z Thursday the area is under northerly flow aloft with the upper
low over NW OK and the TX Panhandle. An upper low center is over
Manitoba sliding eastward across Canada. By midday Thursday another
low is moving southeastward out of Saskatchewan into E MT and the
Dakotas. Showers are expected to be coming to an end Wednesday
night, followed by Thursday morning temperatures in the upper 20s
to middle 30s and a pleasant afternoon in store with temperatures
climbing near to slightly above normal, into the middle 60s to
middle 70s.
Flow briefly backs towards the west late Thursday-early Friday as
the positively tilted trough slides southward into CO. Flow returns
stronger out of the northwest with the approaching low pressure
system. An associated surface front will move through in this
timeframe, bringing cooler, below normal temperatures and another
round of shower and thunderstorm chances from Thursday evening into
the day on Friday, mainly in the form of rain though some snow
mixing in overnight cannot be ruled out for portions of eastern
CO. This round is expected to be less impactful when compared to
the rainfall expected Tuesday/Wednesday, with most ensembles indicating
QPF near fifteen hundredths to two tenths of an inch total while
the GEFS shows up to a third to four tenths of an inch. With the
disagreement here between models will need to monitor for greater
consistency. In addition to the precipitation chances and cooler
temperatures, Friday`s cold front passage will usher in gusty
north-northwesterly winds of around 35-45 knots. Overnight lows
Thursday night to Friday morning will be in the 30s to low 40s,
with afternoon highs in the 50s.
Into the weekend, the low progresses into TX and our area sees north
to slightly northeasterly flow aloft back to the northwest as a
ridge of high pressure builds into the western CONUS with a low
center over the Great Lakes region within a broad trough over the
eastern CONUS. Another low approaches the west coast by the start of
the work week. As is often the case after a cold front moves through
the area, Friday night into Saturday morning is expected to be
colder than the previous night, owed to the clearing cloud cover,
with temperatures dropping into the upper 20s to middle 30s. We`ll
undergo a warming trend back into the 60s and low 70s by Saturday,
continuing near normal through the remainder of the long term
period.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 940 PM MDT Tue Apr 25 2023
LIFR ceilings associated with on and off showers through the night
are forecast at KGLD. Showers are a bit more widely scattered at
KMCK so keeping VCSH in the TAF along with MVFR ceilings through
sunrise. For KGLD, expecting showers to pretty come to an end
around sunrise or shortly after with IFR ceilings returning and
then rising through the day and through the end of the TAF period.
There is a low chance for perhaps some fog to develop after sunset
Wednesday as skies clear out and winds become light and variable.
Overall uncertainty with the coverage and magnitude so will leave
out of the TAF for now.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...Trigg
SHORT TERM...JRM
LONG TERM...CC
AVIATION...Trigg
Area Forecast Discussion
National Weather Service Green Bay WI
1023 PM CDT Tue Apr 25 2023
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Wednesday
Issued at 240 PM CDT Tue Apr 25 2023
Synopsis: The latest RAP analysis shows a large upper level low
spinning across the central and eastern Great Lakes early this
afternoon. This low will slowly drift off to the north over the
next 24 hours. Meanwhile, high pressure stretching from Hudson Bay
to the northern Mississippi Valley will become centered over the
western Great Lakes tonight and the central Great Lakes on
Wednesday.
Sky/Precip: With steep low level lapse rates, a widespread
convective cloud field developed by late morning today. Haven`t
seen signs of showers popping up, but wouldn`t be surprised to see
a few spotty showers develop through early this evening. Patches
of convective clouds will likely linger into the evening hours,
but in general, a gradual clearing trend should occur tonight,
leading to mostly clear to partly cloudy conditions after
midnight.
Patchy ground fog is possible late tonight as high pressure
arrives and winds decouple. Central and north-central WI appear to
have the highest potential.
Convective clouds will likely develop again by late morning on
Wednesday. Cloud bases will be higher than today and no precip is
expected.
Temperatures: Remained close to the best performing guidance for
highs and lows over the next 24 hours. Did drop lows a couple
degrees in the cold spots tonight.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 240 PM CDT Tue Apr 25 2023
Overall, looking at a fairly stagnant weather pattern throughout
the long term forecast with an upper low parked across the Great
Lakes. This will keep cool, cyclonic flow across the forecast
area, with occasional showers and below normal temperatures.
On Wednesday night and Thursday, this pattern will not have
completely established itself yet. High pressure will depart, with
incoming mid- level shortwave and isentropic lift, which will help
generate rain. Rain will be likely across northern WI closer to
the main energy, with a chance across central into east-central
WI. Despite the rain and clouds, WAA will help boost temperatures
closer to normal on Thursday, with highs in the middle 50s to
lower 60s.
Another shortwave approaches the area Friday, but may hold off
until the evening. Wisconsin will remain in the `warm` airmass on
Friday ahead of this shortwave, allowing highs to warm into the
upper 50s and low 60s again.
By Friday evening, shortwave comes through, which is part of the
much broader upper trough. Over the weekend this trough becomes
and upper low and models are in fairly good agreement showing this
low just spinning over the Great Lakes through the weekend and
into at least the first half of next week. Cooler air will get
wrapped into this which will keep temperatures below normal.
Precipitation will not be constant, but the chance will exist
everyday. Timing will depend on individual shortwaves, but overall
expecting precip through the period be to below normal. Snow or a
rain/snow mix is possible across the Northwoods, otherwise ptypes
will be predominately rain.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1022 PM CDT Tue Apr 25 2023
A weak anticyclone will pass southeast through the area during the
TAF period. It`s still possible some St/FG could form late
tonight, though have not seen any sign of that happening yet. Some
diurnal cloudiness will reform tomorrow, though anticipate more
of a SCT-BKN coverage compared to the BKN-OVC coverage of today.
Bases should be high enough to maintain VFR conditions.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM.....MPC
LONG TERM......KLJ
AVIATION.......Skowronski
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
956 PM EDT Tue Apr 25 2023
.SYNOPSIS...
Clouds and light precipitation traverse the region through
Tuesday night as a cold front and shortwave trough swing
through. High pressure then builds in on Wednesday and briefly
dries out conditions before a more robust system moves in
Thursday, bringing in more widespread precipitation.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
A weak cold front will continue to push southeast through our
area during the overnight hours while some mid level energy
rotates southeast across northern and central Ohio. Some of the
models are hinting at some weak low/mid level convergence
developing overnight, possibly in association with a very subtle
low level jet. This may be enough for an axis of isolated to
scattered showers to develop in the early morning hours
somewhere across central portions of our fa. Will therefore
allow for 20/30 pops to sag slowly south across portions of our
area overnight, similar to what the latest HRRR is suggesting.
Cloud cover forecast will be difficult tonight as we have seen
some partial clearing early this evening but will likely see
some clouds reforming overnight with the weak convergent
boundary. This in turn makes for a tough temp/frost forecast as
any areas that end up remaining less cloudy will likely at
least some patchy frost development. Given the uncertainty
though, will generally stick with the ongoing forecast with
lows mostly in the 35 to 40 degree range and continue with the
frost advisory across our northwest.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
High pressure across the Great Lakes region will be our primary
weather driver through the day Wednesday. Northerly flow will
usher in some drier air and allow for clouds to dissolve
through the late morning hours. Daytime highs remain just below
seasonal normals, but there will be increasing sunshine as we
progress into the afternoon hours.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
An active long term pattern will be in place for the extended. A
system will work up from the south on Thursday. There are some
timing differences with this system that will have an impact on
temperatures on Thursday. There is consistency with the
precipitation overspreading the region by Thursday evening and have
high precipitation chances Thursday night. There will also be the
potential for a few embedded thunderstorms. The slow moving low
pressure system will continue to bring rain to the area on Friday
into Friday evening.
With an upper low over the Great Lakes for the weekend and into
early next week there will be several systems that work into the
region. Temperatures will be below normal for much of the extended
timeframe with daily wind gusts Sunday through early next week.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
It will be tough to rule out a few spotty light rain showers or
sprinkles tonight as a weak cold front continues to move
southeast across our area. A brief period of MVFR cigs will be
possible late tonight into Wednesday morning, mainly across our
northern areas. Otherwise, high pressure will build into the
region from the north through the day on Wednesday. this will
lead to a decreasing cloud trend though late morning and into
the afternoon.
OUTLOOK...MVFR/IFR conditions are possible Thursday night into
Saturday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Frost Advisory from 2 AM to 9 AM EDT Wednesday for OHZ026-034-
035-042-043.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Clark
NEAR TERM...JGL
SHORT TERM...Clark
LONG TERM...
AVIATION...JGL
Area Forecast Discussion
National Weather Service Pueblo CO
842 PM MDT Tue Apr 25 2023
.UPDATE...
Issued at 833 PM MDT Tue Apr 25 2023
Quick look at latest HRRR and currently arriving 00z NAM continue
to trend slightly southward with the heaviest precip overnight
into Wed morning, with main band through Pueblo County into the
Wet Mountains and lighter amounts farther north. At this point,
won`t make any changes to highlights, but will likely begin to
dial back snowfall amounts over Teller/El Paso Counties (including
Colorado Springs area) with the next forecast update, as model
QPF in these areas has definitely trended downward. Big winner in
terms of snowfall looks to be the Wet Mountains, with amounts in
excess of 3 feet over the higher peaks by late Wed. Lower
elevations of Pueblo County will do well with rainfall, as over an
inch has already fallen in many locations (0.86 here at the
airport as of 830 pm), with another inch looking possible by Wed
midday, especially south of Highway 50.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 309 PM MDT Tue Apr 25 2023
Key Messages:
1. Heavy mountain snows to impact the southeast mountains and
portions of the I-25 corridor tonight into Wednesday
2. Marginal strong to severe thunderstorm risk continues for
southern portions of the southeast plains through early evening
An intense upper low over UT will continue to track southeastward
into northeast NM by Wednesday morning...spreading intense lift
across southern CO. A well defined baroclinic leaf will develop
across the southeast mountains and plains this afternoon and
evening. Then, as the system drops southward a well defined TROWAL
wraps around its northern and western periphery bringing an intense
period of precipitation with the potential for 1 to 3 inch snowfall
rates focused across the southeast mountains tonight into Wednesday
morning. With impressive isentropic upglide across the area, we are
still looking at widespread QPF amounts of at least an inch across
the plains with pockets of 2 inches or more along the east slopes of
the Wets where upslope will amplify precipitation amounts. This will
be a high end event for the southeast mountains with snow measured
in feet. Still looking at the heaviest snow focusing on the east
slopes and higher elevations of Pikes Peak and the Wet Mountains.
Maximum totals of 1 to 3 feet will be possible. The southern Sangres
and Raton Mesa will be flirting with a dry slot which will cut back
precipitation amounts during the early part of the storm, but wrap
around precipitation appears to bring healthy QPF totals of around
an inch for the latter half of the storm.
Snowfall accumulations along the I-25 corridor will be highly
variable and dependent on the timing of the drop in snow levels
tonight. Diabatic cooling under the upper low and during the
heavier precipitation rates are likely to drive snow levels down to
5000 feet or lower at times. This will yield amounts in the 1-2 inch
range on grassy surfaces for northern Pueblo and far southern El
Paso counties...to 4 to 8 inches across much of Colorado Springs and
Huerfano county...to over a foot on the west side of Colorado
Springs, for Beulah and Rye, and locations to the west of
Walsenburg. Lots of variability in snowfall amounts can be expected
along the upper Arkansas River Valley of Fremont, Chaffee and Lake
county as well, with Canon City seeing an inch or two at times, to
over 6 inches near the higher terrain. If snow levels drop more
quickly, then snow could stack up even more than anticipated given
the heavy precipitation rates. Main impacts to roads will be in and
near the mountains, Monument Hill, and around Walsenburg and Raton
Pass. Lower elevation roads will get slushy at times with poor
visibility during the heavier snow switch over, but with
temperatures dropping to around freezing, residual ground warmth
will allow them to melt out during lighter precipitation and after
sun-up Wednesday. Overall highlights still look on target. Some
locations in the warning areas will come up shy away from the
mountains, while other locations achieve warning amounts quite
handily. The same can be said for the advisory areas though
restrictions to visibility during the snow switch over may magnify
impacts even if snow amounts come up shy.
Activity will decrease from north to south on Wednesday as the
system drops southward into the TX panhandle by afternoon. Ending
times for the warnings across the southern sections still look good.
Shaded high temperatures towards the colder side given persistence
of the storm out east and lingering showers and clouds through the
afternoon.
As for the strong to severe thunderstorm potential this evening,
still looking at elevated instability north of the surface surface
boundary, with storms carrying more of a small hail risk across
northern portions of the risk area. Farther south across Las Animas
county there is a better chance for surface based convection with
quarter size hail, damaging winds and a non-zero risk for a tornado.
Best helicity will hug the northern slopes of the Raton Ridge so
this would be the most likely area for any brief tornado
development. By 6 PM the risk should be decreasing as event will
transition towards a more stratiform event and we head into the
heavy snow portion of the storm for the mountains. Some minor
flooding can`t be ruled out for the lower elevations overnight as
widespread persistent rainfall sets in. But overall, it looks like
much needed precipitation for southeast CO.
Stay tuned for updates through the evening. Dynamic storms like
these are prone to snow level changes. Check road conditions before
heading out Wednesday morning. -KT
.LONG TERM...(Wednesday night through Tuesday)
Issued at 309 PM MDT Tue Apr 25 2023
Key messages:
1) Quick-hitting disturbance Thursday night and Friday.
2) Gradual warming Saturday through Tuesday.
Wednesday night and Thursday...Upper low will be located over the TX
and OK Panhandles Wed evening, and will continue to push east out of
the area through the night. Lingering showers across the southeast
corner of CO are forecast to diminish by midnight as the system
departs. Brisk northwest flow aloft and partly cloudy skies settle
in for Thu as the next upper shortwave drops south into MT and WY.
Plan on overnight low temps in the 20s to around 30F for much of the
area, then high temps rebound into the upper 50s to upper 60s on Thu.
Thursday night and Friday...The next shortwave to affect the area
will arrive Thu evening, with the associated cold front likely to
drop south across the Palmer Divide between 6 and 8 PM. Latest model
runs have shown an increase in the strength of this feature, with
likely to categorical pops forecast for much of the area from 6 PM
Thu until around noon on Fri, before activity quickly drops off from
north to south. Current forecast temps have lows in the upper 20s to
mid 30s for much of the area, then highs on Fri in the 40s to around
50F. A drop in the overnight lows will make a huge difference in
realized snowfall, but forecast total snow amounts indicate 6-9
inches for all of the mt peaks, about 4 inches for Monument Hill and
1-2 inches across the San Luis Valley as well as the I-25 Corridor.
Stay tuned as this will likely change, and highlights may be needed
for at least the higher terrain.
Saturday and Sunday...Ridge of high pressure develops over the Great
Basin and Rocky Mt regions, providing for warmer temps and generally
dry conditions, with a potential for isolated convection over the
mts each afternoon. Maximum temps are forecast to climb to seasonal
norms.
Monday and Tuesday...Upper ridge axis pushes east across the Four
Corners Monday, with a deep Pacific low pressure system dropping
down along the CA coastline. Southwest flow aloft increases across
the Desert SW and Four Corners, increasing warmth across CO as well
as aiding in moisture advection. Look for temps to start climbing to
slightly above seasonal normals, as well as an increase in
convection across all of the forecast area both days. Moore
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 309 PM MDT Tue Apr 25 2023
Expect lowering cigs and vis for KCOS and KPUB as widespread rain
and snow showers expand across the area through the evening. Cigs
will drop into the IFR to LIFR category as snow levels drop into the
KCOS area towards 03z, and into the KPUB area around 10-11z. These
conditions will continue into the morning with improving cigs/vis
for KCOS after 12z and after 15z for KPUB. Showers will be possible
at both terminals in the afternoon but under MVFR conditions with
VCSH more likely to cover the scenario.
Strong southwest winds will continue this evening with VCTS/VCSH
possible through through 02z. Main round of -SHRASN will come after
04z with Cigs/Vis dropping into the MVFR range. Improving
conditions expected Wednesday morning as the system pulls away to
the southeast. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until noon MDT Wednesday for COZ058-060-061-
063-072>082-084-085.
Winter Weather Advisory until 6 AM MDT Wednesday for COZ059-062-
066.
Winter Weather Advisory until noon MDT Wednesday for COZ083-086.
Winter Storm Warning until 3 PM MDT Wednesday for COZ087.
Winter Weather Advisory from midnight tonight to 3 PM MDT
Wednesday for COZ088.
&&
$$
UPDATE...PETERSEN
SHORT TERM...KT
LONG TERM...MOORE
AVIATION...KT