Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/08/24
Area Forecast Discussion
National Weather Service Glasgow MT
104 PM MDT Sat Sep 7 2024
.DISCUSSION...
KEY MESSAGES:
1) Upper ridging will bring hot weather to northeast MT for the
rest of today through Monday.
2) A disturbance will move through in the middle of next week,
which is expected to slightly knock down temperatures and bring
opportunities for precipitation.
WEATHER PATTERN OVERVIEW:
There is good ensemble agreement between the CMC, GFS, and ECMWF
on well above normal temperatures occurring across the area
through Monday. An upper level disturbance will pass through
Sunday night, which will push smoke toward northeast MT. The RAP
Smoke model wants to bring smoke into central MT early Monday
morning. Therefore, there is high (60 percent) confidence in near
surface smoke reaching the area on Monday. Little to no
precipitation is expected Monday, but central MT may see isolated
thunderstorms. This may create a dry lightning scenario for fire
starts, especially with cured fuels. Although the NBM is
forecasting winds below fire weather criteria, any stronger wind
speeds and lower relative humidity on Monday may warrant a fire
weather headline.
A mid to upper level trough will move onshore on Tuesday, which
will aid in a shortwave trough pushing into northeast MT on
Tuesday afternoon. The trough will push further east to increase
the chances for precipitation on Wednesday through Friday,
although confidence is low on precipitation amounts and location.
There is a high amount of spread in the NBM on temperatures for
Tuesday onward, which helps reinforce the low confidence on
precipitation. For example, the 25th and 75th percentile values of
78 and 88 for high temperatures on Wednesday in Glasgow,
respectively, in the NBM indicate quite a bit of uncertainty in
the forecast still.
FORECAST CONFIDENCE & DEVIATIONS:
There is high (90 percent) confidence in much above average
temperatures occurring through Monday. There is low confidence on
precipitation timing and location, how much temperatures will
drop, and the arrival of a shortwave trough in the middle of next
week. There is high (70 percent) confidence on at least slightly
cooler temperatures occurring from Tuesday onward compared to
Sunday and Monday this week.
-Stoinskers
&&
.AVIATION...
LAST UPDATED: 2000Z
FLIGHT CAT RANGE: VFR
DISCUSSION: High pressure will maintain dry weather conditions
for the rest of today through tomorrow.
WINDS: For KGGW, southeast at 6 to 12 knots. Otherwise, light and
variable.
&&
.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Goodland KS
936 PM MDT Sat Sep 7 2024
.KEY MESSAGES...
- A few showers and storms tonight and late afternoon/evening
Sunday; severe weather not anticipated.
- Warm, above normal temperatures forecasted through the week.
- A storm system bringing gusty to strong winds resulting in
fire weather concerns mid through late week.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 128 PM MDT Sat Sep 7 2024
Northwest upper level flow continues across the area along with
surface troughing ongoing. The surface troughing will lead to a
tightening pressure gradient throughout the afternoon with
breezy forecasted. Forecast soundings suggest that a breezy
sustained wind is most likely for the area; however across north
eastern portions of the area a 700-500 mb jet moves into the
area which may lead to a few hours later in the afternoon where
sporadic gusts up to 30 mph may be possible. Hazy upper level
skies will continue through the day due to wildfire smoke from
Canada; no visibility restrictions are currently anticipated.
As a result of this haze have went ahead and increased my sky
coverage to account for this haze. 12Z run of the HRRR
Vertically Integrated Smoke suggests that this may continue at
least through the day tomorrow. As for high temperatures, no
change from the previous forecast package as highs in the low
80s to to upper 80s remain forecasted with the warmer
temperatures across the west where higher 1000-500 DAM and
higher 850 mb temperatures reside.
Moving into tonight, an increase in actual mid to high clouds
forecast to increase with the above mentioned jet. As mentioned by
the previous shift a very low chance of showers or storms does
remain possible overnight. RAP 700-500mb moisture tries to increase
from 06-12Z from roughly the Wauneta, Colorado/ NW Dundy county area
southwards towards the I-70 corridor; recent CAMS are also starting
to pick up on this as well. I`m however a little skeptical on
the coverage/intensity of rainfall should it develop given very
dry low levels. However with the consistent signal feel like at
least slight chance pops will be warranted from 06-1 . For
overnight lows used a blend of the ADJMET and SREFBC as those
have been the better performing models as of late. These
actually did lower overnight lows a few degrees into the upper
40s to mid 50s across the area which seems reasonable given dew
points in the same range. I did nudge them up a degree or two
given southerly winds around 10 knots.
Essentially a same upper level pattern is forecast for Sunday, with
slightly higher temperatures than today due to a surface high across
the western CONUS nudging a bit further east. A developing surface
trough leading to some surface convergence looks to occur late
afternoon tomorrow in to the early evening hours. The RAP 700-500mb
level also does suggest some stronger moisture entering the area
which should be enough to initiate a few showers and storms
across eastern Colorado and the KS/CO state line; 12Z runs of
the CAMS also do support this scenario as of now. Severe
weather at this time is not anticipated but some gusty to
strong winds around 50 mph may be possible with the storms as
DCAPE is forecast to be around 1300 j/kg and downshear vectors
around 30-35 knots. CAPE however is forecast to be around 500
j/kg which makes me think that large hail is unlikely but with
30-35 knots of shear present if a storm can mature then perhaps
penny to nickel size hail may be possible. Showers and storms
will then move to the ESE and be out of the area around 06Z.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 128 PM MDT Sat Sep 7 2024
To start the extended weak surface troughing will remain across
the area as warm above normal temperatures will continue to
start the week. High temperatures in the low to mid 90s remain
forecasted along with no clear cut signal for any precipitation.
The main focus will be on Wednesday as a deepening trough
begins to develop across the western CONUS resulting in a
pattern change. Ensembles are in good agreement with the trough
developing, just the overall timing is the discrepancy. Warm,
above normal temperatures will continue at least through the end
of the week with this trough as winds will remain SSW. Drier
air will also begin to push in, especially for the Colorado
counties. Winds will also begin to increase as this trough
deepens leading to gusty winds across the majority of the area.
Wind gusts are currently forecast around 35-45 mph with the
strongest across eastern Colorado. Unfortunately this does
coincide with the lowest RH values leading to the potential for
critical fire weather conditions to develop. Typically in
troughing setups the dry air ultimately does end up pushing a
bit further east so those across the state line will also need
to monitor upcoming forecasts. Some thunderstorm potential is
also possible across the eastern counties Friday as the trough
ejects to the north but is way to far out to get into specifics.
Overall with the trough still 5 to 6 days out a lot can change
so continue to stay up to date with the latest forecasts.
&&
.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 934 PM MDT Sat Sep 7 2024
Both terminals expected to see VFR conditions through the
forecast period. Low confidence on whether rw/trw will impact
each site. Have left out of forecast for now and will monitor.
Winds south-southeast around 10kts. Gusts to 20kts from 16z
Sun-00Z Mon. LLWS 06z-12z Sunday 130@35-40kts for both
terminals.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...Trigg
LONG TERM...Trigg
AVIATION...JN
Area Forecast Discussion
National Weather Service Medford OR
847 PM PDT Sat Sep 7 2024
.DISCUSSION...Current Satellite imagery is showing some cloud
cover across much of southern Oregon and northern California. In
addition, RADAR has shown a few showers and thunderstorms this
afternoon, mainly to the north of Lake and Klamath Counties.
However, there were several plumes of smoke visible from the
radar, and the most prominent plume of smoke was from the
Firestone fire which created a Pyrocumulonimbus and lightning
strikes downwind (north of the fire) in Pendleton`s area of
responsibility.
Luckily, the lightning stayed north of our area, and our Red Flag
Warning for abundant lightning will not verify. We are perfectly
happy with this. Have cancelled that red flag warning as sunset
has limited the thunderstorm activity. As the low pressure system
moves away from our area, we`ll return to hot and dry conditions.
For more information about the forecast, please see the previous
discussion below. -Schaaf
&&
.MARINE...Updated 830 PM Saturday, September 7, 2024...Low clouds,
areas of dense fog and even some drizzle will impact the marine
waters overnight into early Sunday morning, despite improved wind
and sea conditions. However, north winds and steep wind-driven
seas will return late Sunday morning south of Cape Blanco, then
across most of the southern Oregon coastal waters Sunday night and
Monday. Conditions improve again Tuesday night into Wednesday as
weak low pressure moves into the region. North winds are then
expected to return late in the week. -BPN/Spilde
&&
.PREV DISCUSSION... /Issued 639 PM PDT Sat Sep 7 2024/
DISCUSSION...Satellite shows sunshine across areas east of the
Cascades with cumulus moving northward in Siskiyou County and from
the Cascades west. There is also marine stratus that is reaching
into parts of Coos County. The HRRR smoke model is taking out the
smoke in Jackson County sooner than anticipated for the evening,
so added this to more of the area this afternoon.
Radar shows that the showers in northeastern Lake County have moved
farther north. A 15% probability of thunderstorms will be present
with gusty outflow winds possible in the strongest storms with
expected DCAPEs near 1,000 J/kg this afternoon and evening.
Temperatures will still be overall 5-10 degrees warmer than normal
through the rest of the weekend and Monday. After, a trough begins
to reach the Pacific Northwest and near normal temperatures will
return. This means by Tuesday afternoon 80s are in the forecast, and
it will drop from there with 70s possible for highs west of the
Cascades and 60s east Wednesday afternoon.
The troughing will bring the next rain chance to the area later
Tuesday night into Wednesday starting near the coast. Although the
latest model runs are in better agreement that there will be rain
Wednesday, there still are still unknowns on timing and amounts. The
probability to see 0.25" of rain between 5 AM Wednesday- 5 AM
Thursday has increased west of the Cascades to 40-60%. The Euro is
bringing the system in earlier and is forecasting for the low to
keep PoP chances through Thursday whereas the GFS finishes sooner.
For now, have shown a drying trend through the day Thursday with the
last spots in Douglas and Klamath counties to become dry. For
thunderstorms, Tuesday night`s computed CAPEs are nearing 150-300
J/kg near the Coos County coast, and with the west to east movement
of the rain, added a probability of thunder ~10% there. Computed
CAPEs also show 250-500 J/kg Wednesday afternoon east of the
Cascades, so have added a 5-15% probability of thunder for that
area. -Hermansen
AVIATION...08/00Z TAFS...Along the coast and over the marine
waters, stratus and fog will result in continued IFR/LIFR ceilings
for all areas, including North Bend for most of the TAF period.
MVFR/IFR conditions are expected to return to the coastal valleys
tonight as well. Conditions should improve a bit to MVFR along the
coast or even break up to VFR Sunday afternoon, but it should be
short-lived as onshore flow will bring stratus back onshore quickly
around sunset.
Elsewhere, VFR conditions will continue through the TAF period.
Stratus will make a run at Roseburg around daybreak Sunday. At this
point, it`s a 50/50 chance ceilings go BKN at 1500` around 13Z and
last for a few hours, but for now will just have it as SCT, since we
think it will stop short. We`ll monitor how it progresses overnight.
Numerous fires are burning in the area. We don`t think they`ll bring
reduced visibility to the terminals, but MVFR visibilities are
possible in smoke in the immediate vicinity of the fires. -Spilde
FIRE WEATHER...Issued 200 PM Saturday, September 7, 2024...Hot, dry,
and unstable conditions will continue into this weekend. Isolated
to scattered thunderstorms remain a concern for today. Additionally,
gusty winds and low humidities may result in brief or local critical
conditions for areas in the Scott and Shasta Valleys and east of the
Cascades.
Current models show the upper level disturbance along southwest
Oregon coast today, gradually moving inland tonight and east on
Sunday. This is allowing for isolated to scattered showers and
thunderstorms to develop over eastern portions of the area,
including Lake and northern Klamath Counties. This is also a low
(15%) chance for storms into eastern Douglas County this
afternoon/evening. Storms are expect to be mainly isolated, except
for a potential for scattered storms in northern Klamath and Lake
counties. Thunderstorms may have little rain with them and gusty
outflows up to 40 to 45 mph are possible nears storms.
Gusty south to southwest winds and dry humidities are also expected
this afternoon and early evening, for the Scott and Shasta Valleys
as well as for some areas east of the Cascades into southeastern
fire weather zone 624, southern 625 and eastern 285. Conditions may
near critical RH/wind levels in these areas. A headline is in the
forecast for these potential conditions.
Tonight, winds lower but expect areas of moderate recoveries over
the ridges, mainly in southeast 625, southern 625 and northern
California zones (280-285).
Sunday and Monday, temperatures are expected to trend less warm as
another upper trough approaches the region. However, humidities will
remain dry. On Monday, there is also a potential for some breezy
afternoon conditions in Modoc and Lake counties. The trough and
associated front will then move through Tuesday and Wednesday,
resulting in chances for light rain showers and isolated
thunderstorms, cooler temperatures, and a potential for breezy to
gusty winds. Confidence is low on the strength of this trough and
how much rain will arrive, but there is a chance (20-40%) for
wetting rainfall (0.25"+) on Wednesday for areas from the Cascades
west. The thunderstorm potential is current low (10-20%) and is
focused on Wednesday for areas east of the Cascades, mainly in Lake
and Modoc counties.
-CC
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Small Craft Advisory from 2 AM Monday to 11 AM PDT Tuesday for
ORZ021.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory from 2 AM Monday to 11
AM PDT Tuesday for PZZ350-370.
Small Craft Advisory from 11 AM Sunday to 11 AM PDT Tuesday for
PZZ356-376.
&&
$$
Area Forecast Discussion
National Weather Service Melbourne FL
932 PM EDT Sat Sep 7 2024
...New UPDATE...
.UPDATE...
Issued at 924 PM EDT Sat Sep 7 2024
Slow moving, scattered showers and storms continue over the
interior this evening, especially over the Kissimmee River area.
This activity has largely remained over the same areas, though the
HRRR indicates some building back towards the coast will be
possible along outflow boundaries into tonight. Thus, no change
needed to the forecast overnight, which indicates PoPs diminishing
from west to east into the early morning hours. Drier conditions
are forecast late tonight into Sunday morning. However, a few
showers and storms will remain possible along the coast. Main
threats will continue to be lightning strikes, gusty winds, and
locally heavy rainfall.
Overnight lows forecast to remain muggy in the mid to upper 70s.
&&
.AVIATION...
(00Z TAFs)
Issued at 736 PM EDT Sat Sep 7 2024
Widely scattered showers and thunderstorms continue around east
central Florida this evening. Have maintained VCTS for interior
locations through 2Z and will continue to monitor for TEMPOs, but
otherwise current activity is slow moving and should diminish
after sunset. VCSH for coastal terminals from MLB southward
through that timeframe. VFR conditions largely prevailing, though
low stratus will be possible at LEE late tonight into early Sunday
morning. A TEMPO group has been included from 12-14Z. Otherwise,
onshore flow returns Sunday afternoon around 10kts or less.
Scattered to numerous showers and storms will remain possible
after 18-20Z.
&&
.MARINE...
Issued at 422 PM EDT Sat Sep 7 2024
Currently-Sunday... Scattered to numerous showers and scattered
lighting storms are forecast this afternoon and evening, as well
as Sunday afternoon and evening with a stationary boundary near
or north of the local waters. The main hazards are occasional to
frequent lightning, wind gusts up to 30-40mph, and heavy rainfall.
South-southeast winds at 5-10kts are forecast. Seas are expected
to build up to 1-3ft nearshore and up to 4ft over the offshore
waters (20-60nm) and the Gulf Stream.
Monday-Wednesday... (modified previous discussion) Winds remain
predominately onshore Monday and through the middle of next week,
as the stationary boundary lingers across north FL and then
slowly slides southward into the region mid-week. Winds speeds
remain below 15 knots through the period with seas 2-4 feet
through Monday. A building swell will then lead to increasing seas
up to 4-6 feet on Tuesday and then subsiding to 3-5 feet on
Wednesday. High shower and storm chances continue with a greater
potential for offshore moving storms into early this week.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 75 89 76 88 / 40 70 50 60
MCO 75 92 76 91 / 30 70 30 70
MLB 77 90 77 90 / 50 50 50 60
VRB 76 92 76 91 / 40 40 40 50
LEE 75 90 76 90 / 20 70 30 70
SFB 74 90 76 90 / 30 70 40 70
ORL 76 92 76 91 / 30 70 30 70
FPR 76 91 76 91 / 40 40 30 50
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
UPDATE...Leahy
AVIATION...Leahy
Area Forecast Discussion
National Weather Service San Francisco CA
833 PM PDT Sat Sep 7 2024
...New UPDATE...
.SYNOPSIS...
Issued at 130 AM PDT Sat Sep 7 2024
A slight cool down will begin today as a weak upper level trough
impacts the region, yet temperatures remain above seasonal norms
through early in the upcoming week. By midweek, a more robust
cooling trend will kick off as a stronger upper level through drives
southward out of the Gulf of Alaska.
&&
.UPDATE...
Issued at 823 PM PDT Sat Sep 7 2024
Temperatures across our area did cool slightly from yesterdays
highs across our area, mostly around 2 to 5 degrees, with that
trend continuing through the middle of next week. Many spots that
are in the 90s to low 100s today will be 20 to 25 degrees cooler
by Wednesday afternoon.
Low marine stratus is a little slower working south from the Bay
Area to Monterey Bay this evening but will eventually impact
most of our coastal locations with low ceilings, patchy to dense
fog at times and light drizzle through the remainder of the
overnight hours into Sunday morning.
&&
.SHORT TERM...
Issued at 112 PM PDT Sat Sep 7 2024
(This evening through Sunday)
A ripple through the longwave pattern over the West Coast this
afternoon thanks to an upper low sweep eastward through N CA/S OR.
While this feature is bringing showers and thunderstorms up north
it`s resulted in sunny, but cooler conditions across the Bay Area
and Central Coast. Afternoon visible satellite shows marine layer
stratus hugging the coast, but inland sunshine. Latest 24 hour
trends shows many locations running similar to or colder than 24
hours ago. Despite the "cooldown" there are still many locations
well above 90 degrees. One notable place is the Big Sur RAWS
sitting at 98 degrees. Pretty impressive given the proximity to
the coast. Definitely has a shot at eclipsing 100 degrees. Other
far interior locations away from the coast range from 95-105
degrees. These locations have a moderate HeatRisk, but coverage
isn`t widespread enough to warrant another Heat Advisory.
Fire Weather concerns continues this afternoon as well. Area of
greatest concern are the interior N Bay Mts. Last night featured
no humidity recovery with places lingering in the single digits
for RH. The same is true this afternoon with places holding steady
below 10%. Winds are breezy with gusts up to 15 mph. Bone dry
conditions with some wind will result in elevated fire weather
conditions.
Tonight and Sunday: Marine layer along the coast will gradually
move in. Similar to this morning, fog will once again be possible.
Only subtle changes in the overall sensible weather on Sunday.
Coastal clouds with inland sunshine - repeat from Saturday.
Pockets of 100+ deg possible over interior Monterey/San Benito.
&&
.LONG TERM...
Issued at 130 PM PDT Sat Sep 7 2024
(Sunday night through next Friday)
Additional, but weaker, ripples roll through the upper level
pattern through early next week. The lower 500mb heights and
cooling airmass will allow for additional cooling both day and
night. Onshore flow will persist, which will lead to a deepening
of the marine layer and increasing night/morning low clouds. Have
added coastal drizzle to the forecast (late night/early morning)
through this timeframe as well.
A more pronounced upper level trough develops by Tuesday
night/Wednesday over the PacNW. Given all of the wildfire over
OR a lot of hope was riding on this system being wetter, but sadly
recent trends are drier. As for our area, some drizzle is
possible, but looking more inside slider-ish for
Wednesday/Thursday. Temperatures remain cooler on
Wednesday/Thursday, but more importantly winds begin to shift with
an offshore component. At this point it doens`t appear to be a
big offshore setup, but something we`ll be watching nonetheless.
&&
.AVIATION...
(00Z TAFS)
Issued at 541 PM PDT Sat Sep 7 2024
The marine layer depth varies from several hundred feet to as much
as 1300 feet vicinity Bodega Bay (profiler data) along the coastal
North Bay to at least northern San Mateo County sloping down to near
sea level from southern San Mateo County to Monterey County. Visible
imagery shows the stratus/no stratus line is nearly stationary from
Pacifica extending out southwest across the coastal waters, the
advected stratus clouds on northwest winds are eroding upon arrival
into the warmer thermal ridging aloft to the south.
Model forecasts including HREF are currently over-forecasting
areal stratus coverage and ceilings to the south of the aforementioned
stratus/no stratus line. At least two things would allow the stratus
and fog to develop to the south tonight (1. radiative cooling which
will happen after sunset and 2. a weakening of the thermal ridging
aloft), a weakening of the ridge aloft does not look favorable based
on same model forecasts thus stratus and fog development along the
coast to the south will be slower to develop than models currently
forecast. This is a good example of how complex meteorology is and
this is only an example of a smaller scale here in our forecast
area. When we get to the mix of warm and cool season transition, the
complexity and interactions can increase much more.
For the 00z TAF cycle, decided to slow stratus /IFR/ forecast
arrival/development times for SFO, OAK, SJC, MRY and SNS in
inherited TAFs. If the thermal ridge aloft and lower level
temperature inversion described above holds together fairly well
tonight, it may take even longer for stratus and fog to develop
otherwise under radiative cooling and compressed marine layer
expect increasing probability of coastal and nearby coastal valley
fog /VLIFR-IFR/ tonight and Sunday morning. Highest probability is
for VFR to extend well into the evening for all TAF sites, with
IFR currently limited to the immediate coastline from approx Half
Moon Bay-Pacifica and the coast northward. This is also a great
example as to how helpful satellite imagery is, including surface
observations, spotter reports, etc.
Vicinity of SFO...Moderate to high confidence VFR prevails this
evening, 300 degree surface wind may help continue VFR at SFO.
Upstream stratus is nearby per satellite imagery, but is hung up
along the coast upon meeting the lower level thermal ridge hovering
over the SF Peninsula and areas to the south and east. Best guess
is for BKN stratus ceiling developing by 08z tonight and continuing
to 17z; the RAP model may be overdoing the stratus /IFR/ duration
tonight too beginning 04z, but don`t want to completely rule out
stratus at SFO tonight either, thus factoring in "later is better"
into the forecast. Otherwise west to northwest wind near 20 knots
eases to near 10 knots tonight and Sunday morning, increasing to
15 to 25 knots Sunday afternoon and early evening.
SFO Bridge Approach...Similar to SFO except the approach may have
longer duration VFR into early Sunday morning before any chance of
IFR ceiling development. Not seeing anything unusual about potential
stratus feed Sunday morning thus mix out time should be quick Sunday
morning.
Monterey Bay Terminals...Low to moderate confidence VFR prevails
through the evening, chances of VFR holding look good so far based
on satellite imagery. Post sunset radiative cooling however is when
things may change quicker, thus the low to moderate confidence in
the evening forecast. Data at buoy 92 Monterey Bay is very helpful,
currently showing the air temp is a little warmer then the sea surface
temp (vs if the air temp was cooler at the air/sea interface, upward
heat flux) which matches the clear sky currently observed over the
Monterey Bay. In short it will take a little time for the stratus
to advect here into the thermal ridging aloft. By late evening and
overnight expect at least patchy stratus and fog /VLIFR-IFR/ nearby
and potentially reaching the Monterey Bay terminals. Any stratus
and fog Sunday morning will mix out to VFR by late morning. Mainly
onshore winds 5 to 12 knots except light and variable tonight and
Sunday morning.
&&
.MARINE...
(Tonight through next Thursday)
Issued at 446 PM PDT Sat Sep 7 2024
Moderate to breezy north and northwest winds continue through the
weekend with occasional gusty winds over the southern waters.
Northwest winds strengthen and wave heights increase over the
California coastal waters ahead of an incoming low pressure system
by the middle of next week with unsettled conditions persisting
through the end of the week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
SHORT TERM...MM
LONG TERM....MM
AVIATION...Canepa
MARINE...Murdock
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Area Forecast Discussion
National Weather Service Pueblo CO
547 PM MDT Sat Sep 7 2024
.KEY MESSAGES...
- Isolated thunderstorms mountains/valleys and I-25 corridor
this evening, mainly south of Highway 50.
- Slightly warmer Sunday, with isolated afternoon showers and
thunderstorms once again.
- Isolated to scattered showers and thunderstorms across the
higher terrain each afternoon and evening through the extended
period.
- Enhanced fire danger possible on Thursday for portions of the
plains.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 227 PM MDT Sat Sep 7 2024
Currently...Isolated thunderstorms have returned to srn CO this
afternoon, as increased low/mid level moisture and weak upward
motion from wave sliding se over the 4 corners upper ridge have
combined to generate some weak storms over the ern San Juans/srn
Sangres as of 2 pm. Temperatures have reached the 80s to low 90s at
most lower elevations and across the plains, while mountains and
high valley readings are in the 60s/70s.
For the remainder of the afternoon into this evening, expect
isolated to scattered storms to continue to form over the mountains,
eventually drifting across interior valleys and the I-25 corridor,
especially early this evening. CAMs continue to keep best coverage
of storms south of Highway 50, and HRRR has been consistent in
showing some windy storms developing near Canon City 5-6 pm, which
then move across Pueblo County 6-8 pm. Given rather modest CAPE
(values under 1000 J/KG) and LCLs above 10k feet, expect gusty
outflow winds to dominate most activity, though a brief burst of
moderate rainfall and some small hail will be possible under any
heavier storms. Most convection doesn`t push too far east of I-25
before dissipating 8-10 pm, so won`t extend pops onto the sern
plains at this point. Clouds then clear overnight with seasonably
cool min temps expected.
On Sunday, upper level ridge builds slightly, which will give a 1-3
degf boost to max temps at most locations. Recycled moisture from
Saturday`s storms will likely be sufficient for another round of
afternoon convection over the mountains, though lack of any
significant forcing suggests rather weak/sparse activity. Models
favor the ern San Juans for highest pops, and did add some very low
pops to Kiowa and Baca Counties on the plains where stronger surface
sly flow and weak low convergence could generate a storm or two, as
hinted at by the HRRR. Again, more wind than rain with the majority
of activity, though a brief downpour and some small hail will be
possible with strongest storms.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 227 PM MDT Sat Sep 7 2024
Sunday night and Monday...A somewhat flat ridge will be in place
across the region through Monday evening, while an upper disturbance
crosses the Rocky Mt region to the north. Ongoing showers and
thunderstorms Sunday evening are expected to dissipate quickly once
the sun sets. Also, available moisture is limited, so this upper
shortwave, coupled with daytime heating, will likely only help
initiate isolated convection across the mts and high valleys Mon
afternoon and early evening, with activity once again dropping off
quickly with sunset. Minimum Temps Sun night are expected to cool
into the upper 30s to mid 40s for the high valleys, and 50s for the
plains. Highs on Monday will climb to above normal levels with
readings in the 70s to around 80F for the high valleys, and mid 80s
to mid 90s for the plains.
Tuesday and Wednesday...A change in the upper pattern begins to take
place starting Tuesday as the upper ridge over the region pushes off
to the east, and a trough of low pressure off the Pacific NW coast
deepens Tue, then moves onshore across WA and OR on Wed. West to
southwest flow aloft begins to increase both days, and especially on
Wed, drawing some Pacific moisture across the Desert Sw and Four
Corners regions into the western half of CO. A weak shortwave in the
upper flow will serve as the spark for a slight increase in
convection chances across the higher terrain both days, with
scattered pcpn chances forecast for the Continental Divide and the
central mts, and isolated convection for the remaining high terrain.
Plan on highs in the 70s for the high valleys, and mid 80s to lower
90s for the plains.
Thursday and Friday...Upper low located over the Pacific NW by mid-
week will push across ID on Thu, then MT on Fri. This pattern with a
fairly strong trough over the western third of the country will
produce stronger southwest flow aloft across CO, leading to enhanced
downslope flow, continued warm temps and drier conditions. Long
range models are leaning towards a more dry solution across the
higher terrain both days with just isolated showers and storms over
the higher terrain, with the best chances over the central mts.
However, across the eastern plains there is a growing area on Thu
where critical fire weather conditions may develop. Moore
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 543 PM MDT Sat Sep 7 2024
VFR conditions are expected to prevail for all TAF sites (KALS,
KCOS, and KPUB) throughout the forecast period. VCTS/VCSH is
expected this evening for all TAF sites. There is very low
confidence (less than 20 percent probability) of VCTS/VCSH at KALS
towards the end of the forecast period. If SHRA/TSRA does occur and
moves on station at KALS, it could temporarily reduce CIGs and VIS
to MVFR/IFR criteria. It could also result in periodic windshifts
and increased wind speeds at the KALS terminal. Winds will be
generally light (10 kts or less) and primarily influenced by diurnal
regimes at all terminals throughout the forecast period, and only
disrupted by convective outflows while VCTS/VCSH is present.
-Stewey
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...PETERSEN
LONG TERM...MOORE
AVIATION...STEWARD
Area Forecast Discussion
National Weather Service San Diego CA
201 PM PDT Sat Sep 7 2024
.SYNOPSIS...
Hot conditions will continue into Monday, with well above average
temperatures across the area. There are chances of showers and
thunderstorms in the forecast from the valleys to the deserts this
afternoon and Sunday afternoon. Main impacts from any storms that
develop will be locally heavy rain, erratic gusty winds, and
frequent lightning. A trough is expected to move into the western
states by the middle of the week, leading to a quick cooling trend
with drier weather.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
As of 1 PM, a few thunderstorms have developed in the mountains and
on the western foothills of the mountains. Temperatures this
afternoon for the most part are running 3 to 7 degrees cooler than
this time yesterday. Highs on Sunday are expected to be a few
degrees cooler than today for most places away from the coast.
Weak easterly flow is expected Sunday morning which will prevent
cooler marine air from making it onshore and resulting in highs 3 to
5 degrees warmer than today along the coast. Well above average
temperatures are expected for the coast and valley areas through
Monday.
The area of high pressure over the Western United States has shifted
to the northeast, allowing for an influx of monsoonal moisture into
the region today and Sunday. Thunderstorms this afternoon are
expected in the mountains and locally into the mountains
foothills and deserts. Storms that develop are capable of
producing gusty winds, frequent lightning, and heavy downpours
that lead to areas of flooding. Chances of thunderstorms remain in
the forecast for Sunday afternoon, with slightly higher
probability of occurrence and more coverage compared to today.
Thunderstorms tomorrow have the potential to develop in portions
of the valleys. Precipitable water values will remain elevated
with HRRR and WRF models showing a higher chance for storms
capable of downburst winds in valley locations. HREF peak rain
rates for Sunday afternoon are mostly 0.40 to 0.60 inches per
hour, locally up to 0.75 inches per hour. Monsoonal moisture
decreases by Monday but is still sufficient for storm development,
chances of thunderstorms are in the forecast for the mountains
Monday afternoon.
A trough will develop and move over the Gulf of Alaska on Monday,
dipping southward along the West Coast by Tuesday. This will lower
heights and increase onshore flow, leading to cooling west of the
mountains with highs below the century mark for most inland areas
and near 80 degrees toward the beaches. The trough will continue to
dig south and east across the West by Wednesday and Thursday.
Most places will cool by 5 to 10 degrees from Tuesday to Wednesday.
This will bring highs near to slightly below average by the middle
of the week. Weak troughing looks to continue through the end of the
week, which will keep temperatures near average. The trough will
also help increase winds across mountain passes and on desert
mountain slopes. The marine layer will also build through the week,
increasing night and morning low clouds/fog for the coast and
adjacent valleys.
&&
.AVIATION...
072030Z...Coasts...Aside from a few rogue patches of low clouds/fog
along the immediate coast, mostly clear skies and VFR prevails. SCT-
BKN clouds at/above 12,000 ft MSL could redevelop overnight and
areas of smoke is possible along the coasts from ongoing wildfires
in Mexico and San Bernardino. Low clouds/fog is possible at times
along the coast between 06-16z, but chances in long duration CIGs or
VIS restrictions is low (10-20%).
Valleys/Mountains/Deserts...Scattered thunderstorms have developed
largely across the mountains this afternoon, though a few may
meander into the western foothills. CB bases near 12,000-15,000 ft
MSL with tops to 30,000 ft MSL. Gusty outflow winds, strong
up/downdrafts and local vis restrictions in RA VCTY TSRA are
possible with any storm. Storm activity will dissipate by 02-03z.
SCT-BKN clouds at/above 12,000 ft could redevelop overnight. Areas
of smoke is expected near ongoing wildfires through Sunday
afternoon. Scattered thunderstorms are expected Sunday afternoon as
well, with a 30-50% chance over the mountains, and a 20-30% chance
over the hills/valleys and deserts.
&&
.MARINE...
No hazardous marine weather conditions are expected with
predominantly northwest flow through Thursday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Monday for Orange County Coastal
Areas-San Diego County Coastal Areas.
Excessive Heat Warning until 8 PM PDT Monday for Orange County
Inland Areas-San Bernardino and Riverside County Valleys-
The Inland Empire-San Diego County Valleys-Santa Ana
Mountains and Foothills.
PZ...None.
&&
$$
PUBLIC...CO
AVIATION/MARINE...Munyan