Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/27/24
Area Forecast Discussion
National Weather Service Denver/Boulder CO
701 PM MDT Fri Jul 26 2024
.KEY MESSAGES...
- Numerous showers and thunderstorms for the mountains today and
Saturday, with scattered storms on the plains.
- Elevated fire weather conditions are expected over the
higher terrain and South Park on Sunday and Monday due to hot,
dry, and windy conditions.
- Trend towards hot and dry continues late weekend into next week.
- A few daily records tied or broken is very feasible with the upcoming
&&
.UPDATE...
Issued at 653 PM MDT Fri Jul 26 2024
The main batch of storms for today continues to move east across
the plains, with enough moisture convergence to keep them going a
bit longer, though there are starting to be signs of weakening.
Upstream there are a few clumps of storms in a drier airmass.
These should fade with nightfall, though there`s still a slight
chance they make it across the mountains. Main update at this time
is for these PoP details.
&&
.SHORT TERM /Through Saturday/...
Issued at 219 PM MDT Fri Jul 26 2024
While smoky skies have lingered into the afternoon along the Front
Range, associated air quality has improved over the past few days.
With the shifting wind patterns aloft transitioning to a more
westerly pattern later today, continued improvements are expected.
The only caveat is whether the W/WSW flow starts to bring in smoke
from the wildfires currently burning in California. The latest run
of the HRRR Vertically Integrated Smoke shows a hefty plume of
high concentrations expected to enter western WY and southwestern
Utah in the next day. This will continue to be monitored in the
coming days. The shifting pattern will also be responsible for
increased moisture across the forecast area today and tomorrow.
Current satellite imagery shows a plume of mid- and low- level
moisture extending from the Baja region into central and eastern
Canada and passing directly through Colorado. Slow moving storms
have already developed over the mountains early this afternoon.
SPC mesoanalysis currently shows PWAT values between .7" to .8"
across the forecast area. These storms are expected to be
scattered in nature and the HREF indicates a 40% chance that some
of the stronger storms may contain pockets of .25"/hr
accumulations. The HREF LPMM accumulated precipitation portrays
our areas of greatest concern for heaviest rainfall to be in
portions of central Larimer County, and southern Clear
Creek/northern Park Counties between the 2-5 PM time frame. The
storms in Larimer County may develop or pass over some of our burn
scars and will be monitored for flash flooding concerns. With
forecast soundings showing DCAPE values surpassing 1000 J/kg,
gusty outflows are expected with these storms as they move east
off the higher terrain and begin to dissipate over the lower and
less favorable environment across the plains. Gusts are expected
to be in the 30-35 mph range with a chance of a few gusts
surpassing that with the stronger storms. Overnight temperatures
are forecast to be in the 60s across the plains and 40s for the
higher elevations.
Tomorrow will bring another round of scattered to numerous storms
and showers. With more instability expected, there is a better
chance of these storms making their way onto the plains than
today`s. With the increased instability and some better shear,
these storms have a better chance of becoming slightly more
organized which could bring increased chances for producing some
hail, mainly for the northeastern portion of the forecast area.
High temperatures are expected to surpass the 90s once again
across the plains and high 70s/low 80s for the mountains. Expected
cloud coverage should help take the edge of the heat in the
afternoon.
&&
.LONG TERM /Saturday night through Friday/...
Issued at 219 PM MDT Fri Jul 26 2024
At this point in time with the upcoming heat we`re trying to define
if it`ll be 98 degrees, not the band, or 100 degrees across the
urban corridor and 100 to 105 degrees over the plains from Monday
through Wednesday of next week. Ensemble probabilities have been
showing the signal for 100F for several days now with probabilities
inching higher as of today. Tuesday and Wednesday look to be the
hottest days with the coarser ensemble data showing a 60-70% chance
of reaching 100F from the Denver Metro to the north and east across
the plains. That is not to say that the other days during the long
term period aren`t hot, they are just not as hot.
Though not a definite correlation, the last time across the metro
area and plains to make a run at three consecutive days of 100F,
just two weeks ago, 500mb heights were 594dm. At this time we`re
seeing a 90+% chance of having heights exceed that level on numerous
pieces of ensemble guidance. Some moisture does try to increase
later in the period, even with these deeper heights, but cloudiness
could keep us a degree or two cooler by Thursday and Friday of next
week. Any shower or storm activity looks to be confined to the
higher terrain as well, again late period.
&&
.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 653 PM MDT Fri Jul 26 2024
VFR through Saturday. There`s just a slight chance of a shower or
thunderstorm in the Denver area between 03z and 06z which could
produce a wind shift with gusts to 30 knots. Otherwise, southerly
winds will continue at KDEN/KAPA and west winds at KBJC through at
least 15z. By 18z, winds are expected to be northeast, then gusty
mainly northwest winds along with scattered showers and
thunderstorms again in the 21z-24z period on Saturday.
&&
.FIRE WEATHER...
Issued at 219 PM MDT Fri Jul 26 2024
Elevated to critical fire conditions will be in place over the
higher terrain both Sunday and Monday due to gusty winds, low
humidity and above normal temperatures. Across the plains winds
will be lighter, however, hot and dry conditions will lead to
elevated fire conditions.
&&
.HYDROLOGY...
Issued at 219 PM MDT Fri Jul 26 2024
Slow moving storms this afternoon and evening are expected over
the high country, with a chance of some making their way to
adjacent lower elevations. With increased moisture across the low
to mid- levels, some localized heavy rainfall is possible. The
main concern is the limited threat of flash flooding over the
burn scars, mainly for those residing in Larimer County.
Enough moisture will remain across the region on Saturday for
another round of showers and thunderstorms. There will again, be a
limited threat for flash flooding in the burn scars. Hot and dry
conditions are the main concerns Sunday through the end of the new
work week.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Gimmestad
SHORT TERM...Bonner
LONG TERM...Heavener
AVIATION...Gimmestad
FIRE WEATHER...Bonner/Heavener
HYDROLOGY...Bonner/Heavener
Area Forecast Discussion
National Weather Service Des Moines IA
638 PM CDT Fri Jul 26 2024
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Less than 15% chance of an isolated storm this evening
- Gradually turning hotter this weekend into at least the middle
of next week with heat headlines possible toward midweek.
Heat index values Monday and Tuesday well into the 90s to near
100 degrees with more widespread 100 to ~105 degree heat
index values Wednesday southern into central Iowa
- Storm chances Sunday night/Monday with a low risk of severe weather
- Another round of storms around midweek with severe weather
possible, but timing and location remain uncertain
&&
.DISCUSSION...
Issued at 205 PM CDT Fri Jul 26 2024
It was rather impressive this morning with the storm that parked
over Appanoose County. The elevated boundary, copious amounts of
moisture with precipitable water values over 1.3 inches and deep
warm cloud depths, moisture transport into the boundary, and hardly
any low level flow kept storms nearly stationary. A CoCoRaHS
observer had over 2 inches west of Centerville with a trained,
reliable spotter north of Centerville recording almost 4 inches with
those reports as of 7 or 8am. PoPs were held into this afternoon
over our southeastern forecast area as these storms continued to
fester, but have now since diminished. Along the boundary, which
extends from southeastern Iowa into north central Iowa, stratus
clouds were stout this morning. However, these clouds have been
breaking up leaving a mixture of sunshine and clouds this afternoon
in many areas of central Iowa. There does remain high level wildfire
smoke over the state, which will likely linger aloft through
Saturday, resulting in hazy, vibrant red and orange sunrises and
sunsets barring any clouds.
All recent runs of convective allowing models (CAMs) except the RAP
are showing isolated storms popping early this evening somewhere
over central Iowa. This would likely be along the weakening elevated
boundary, but with nebulous forcing it raises questions about
whether anything will develop. With all of the uncertainty will just
run with token PoPs/sub 15%, but will need to monitor. Similar to
Thursday evening, if a storm does develop, brief downpours,
lightning, and perhaps gusty winds given dry subcloud air would be
the main concern.
For the remainder of the discussion covering Saturday through late
next week, will break out by first discussing the upcoming heat wave
and then storm chances. Looking at high temperatures, 850mb
temperatures today should peak around 18 to 20C and result in highs
mainly in the 80s over central Iowa. Saturday and Sunday may be a
touch warmer than today, especially if we start the day sunnier than
today. As we move into early next week, 850mb temperatures increase
about 2C each day Sunday to Monday, Monday to Tuesday, and likely
Tuesday to Wednesday. This should place much of central Iowa into
the upper 80s to middle 90s on Wednesday with the latest National
Blend of Models (NBM) showing probability of reaching or exceeding
90 degrees at 50% or higher across central Iowa. ECMWF is showing
very little in the way of any extreme forecast index (EFI) or shift
of tails during the upcoming heatwave meaning that while it will be
hot and humid, this is not unusual for late July or early August.
Still, seasonal humidity levels are likely from this weekend into
next week (dewpoints a few degrees either side of 70). Combined with
the heat, this will result in heat index values well into the 90s to
near 100 degrees Monday and Tuesday with more widespread heat index
values above 100 degrees on Wednesday. A heat headline is certainly
possible Tuesday if not Wednesday, especially considering the
cumulative effect of heat on the body. The experimental HeatRisk is
showing level 3/major HeatRisk (out of a max of 4) in a few places
over southern Iowa Tuesday afternoon with more widespread level
3/major HeatRisk over southern Iowa into parts of central Iowa on
Wednesday.
Now, onto the storm chances. While there is broad scale ridging over
the region today, a shortwave beneath the ridge that is over
Arkansas at midday today will drift northeastward. This shortwave
and weak low level thermal lift could be the impetus for scattered
storms. Some of the more convective happy models are showing this
early afternoon Saturday somewhere over southern or central Iowa.
This, like tonight`s chance, is quite low and have drawn in some low
PoPs over southern Iowa in the afternoon with the main hazard being
gusty winds, lightning, and brief downpours. The more likely period
for any storms from this shortwave will be as it moves into the
state Saturday night into Sunday, particularly over the eastern half
of the state. Shear is lacking so not expecting more than locally
heavy downpours and lightning. As this pulls into the western Great
Lakes Sunday, another upstream shortwave will quickly be approaching
from the Dakotas. This should bring a more widespread chance of
scattered storms later Sunday evening into Monday, including the
possibility of a few severe storms given the instability and higher
deep layer shear values associated with this shortwave compared to
Saturday night/earlier Sunday. This low severe risk is supported by
the SPC day 3 marginal over much of the forecast area along with the
Colorado State University`s machine learning random forest outlook.
Around Wednesday, a more amplified shortwave trough will be moving
through the northern states. The timing of this wave has varied from
Tuesday night to Thursday, but regardless of when this comes through
the region, there will be storm chances. Right now, NBM has too
broad temporal and spatially the PoPs, but that is the uncertainty
of this time. Severe weather may be in play with the stronger
kinematic fields and instability, but where and as already mentioned
when remain big question marks. CSU`s machine learning random forest
outlook has broad brush low probabilities throughout the middle of
next week - not atypical for late July and early August.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 627 PM CDT Fri Jul 26 2024
Areas of MVFR ceilings may affect KMCW and KALO areas through
02z or so, with isolated showers near KDSM. The thunder
potential there seems too low to mention at this point with
nothing currently nearby and the likelihood diminishing into
the evening. Otherwise VFR conditions are anticipated for the
remainder of the period.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
DISCUSSION...Ansorge
AVIATION...Small
Area Forecast Discussion
National Weather Service Quad Cities IA IL
616 PM CDT Fri Jul 26 2024
.KEY MESSAGES...
- Mostly dry conditions tonight and Saturday
- Shower and thunderstorm chances Saturday night and Sunday,
lingering through much of the upcoming week
- Heat and humidity will build Monday through Thursday, with
the potential for heat headlines
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 258 PM CDT Fri Jul 26 2024
Tonight, high pressure will remain just off to the east with dry
conditions forecast. However, there is a moisture axis at 850mb
across the western CWA which will nudge east into the MS Valley.
Showers and storms have been festering on the edge of this most
of the day today. The HRRR has been hinting at some spotty
showers developing during the middle of the night in the north
and spread south into the CWA possibly lingering into mid
morning. Confidence is low on this coming to fruition, so opted
to introduce some higher, but silent POPs, as a place holder.
Lows will be 55 to 60 east and low to mid 60s west.
Saturday will be mostly dry as southerly winds develop on the
back of the high bring increased humidity into the region. If
showers were to develop overnight, they may linger into the day
similar to today. Later on, some actual slight (20) rain chances
nudge into the far south CWA for the late afternoon, as an
upper level wave lifts across MO and IL. Highs will be in the
mid and upper 80s.
&&
.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 258 PM CDT Fri Jul 26 2024
Saturday night through Monday, we will see two main rounds of
higher precip chances. The first will be with the upper level
wave late night Saturday into Sunday night with 40 to 60 percent
chances Sunday afternoon focused across the east half. After a
lull, a cold front will pass through bringing shower and storm
chances (30-50) across the area late Sunday night into early
Tuesday. Modest shear and instability will be present ahead of
this frontal passage, so some storms may be strong to severe.
The SPC has a Marginal Risk, or level 1 of 5, for our far west
and northwestern areas for Sunday night into early Monday morning.
Previous Discussion with some minor edits:
For Monday through the upcoming week, we will continue to have
periodic chances of showers and storms as a large area of upper-
level high pressure develops over the south-central CONUS,
placing our region on the northern end of a large heat dome.
Zonal flow aloft will become established over our region,
leading to a series of mid-level shortwaves to traverse the
region. How this will evolve convectively is uncertain, given
that the earlier rounds of storms will augment the environment
to impact the latter rounds of storms. So, it`s difficult to
really pin down timing and spatial coverage of storms at this
time.
Additionally, the temperature forecast will be highly dependent
on the timing of these storms as convection during the daylight
hours will help keep conditions cooler than what the NBM is
suggesting. If storms don`t develop during peak heating, high
temperatures could reach the lower to middle 90s. With increased
humidity, heat indices of 95 to 100, or more, are possible.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 615 PM CDT Fri Jul 26 2024
VFR conditions will prevail through the TAF period, with light
southeasterly winds. No sig wx is expected at this time.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...14
LONG TERM...14
AVIATION...Gunkel
Area Forecast Discussion
National Weather Service Grand Junction CO
608 PM MDT Fri Jul 26 2024
.KEY MESSAGES...
- Scattered to numerous showers and storms continue into the
evening.
- Storms will be capable of producing gusty winds, hail up to 1"
in diameter, and heavy rainfall. Localized flash flooding is
possible, particularly in the steep terrain and other
vulnerable areas.
- Warm and dry conditions return Sunday and persist through
much of next week.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 212 PM MDT Fri Jul 26 2024
We continue to anticipate scattered convection across much of the
forecast area this afternoon and evening as monsoonal moisture
interacts with pulses of shortwave energy advecting through the
southwesterly flow aloft. Dew point temperatures this morning were
in the 50s area wide, but it became apparent that most of the CAMs
were underdoing dew point temperatures. For example, the HRRR has
dew points upwards of 10 degrees too cool compared to ground
observations. The NAM Nest seems to be the most representative at
this time. With satellite imagery showing sufficient clearing after a
cloudy start to the day, convection this afternoon will likely
realize forecasted mixed-layer CAPE values of 500-1200 J/kg. Deep-
layer shear on the order of 15-25 knots could support a few isolated
severe storms, but organized severe convection is not likely with
limited shear in place. Gusty outflow winds up to 50 mph and hail up
to 1" in diameter are the primary threats. Localized heavy rainfall
is also on the table. CIN increases quickly after sunset but a few
showers and storms may continue into the evening.
A similar story again tomorrow afternoon and evening with the
biggest difference being increased shear with an upper-level jet
moving in overhead. The biggest forecast uncertainty is how quickly
monsoonal moisture will begin to erode. All of the hi-res models
show decreasing PWATs late tonight into tomorrow, but given that
they are struggling with the moisture currently available and that
the models are usually too quick to clear the monsoonal moisture
from the region, we cannot rule out scattered convection similar to
what we will see today. If the mositure does decrease, the coverage
of convection will also decrease. A drier atmosphere could also lead
to elevated fire weather conditions in parts of eastern Utah
tomorrow afternoon with surface winds gusting up to 25 mph, but
given our lower confidence in mositure clearing by tomorrow
afternoon we opted against fire weather headlines at this time.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 212 PM MDT Fri Jul 26 2024
On Sunday a trough tracks from the Great Basin to the Northern
Rockies bringing a midlevel dry punch into the region from the
southwest. Guidance remains aggressive in scouring out moisture from
west to east by Sunday morning, dropping PWATs down to near 50
percent of normal that afternoon. It is always a bit tricky to get
rid of residual moisture post-monsoonal surge, so can`t rule out a
few storms over the mountains Sunday afternoon. If conditions dry
out as anticipated, the potential for near critical fire weather
conditions will be possible. This will be due to the presence of a
60 to 70 kt jet overhead across much of eastern Utah and western
Colorado, resulting in surface gusts right around 25 mph. The
gradient relaxes on Monday which would lead to more localized near
critical fire weather conditions. Continued warm southwest flow
aloft will bring about a warming trend into the midweek point with
temperatures returning to several degrees above normal and even back
to the low triple digits for some of the lower valleys. Early next
week will also see the next trough of low pressure begin to dig into
the Pacific Northwest. Its progression east on Tuesday will usher
the Subtropical High closer towards the Southern Plains, allowing
for monsoon moisture to slowly trickle back into the Four Corners
region on Tuesday and Wednesday. That might be short lived as the
trough to the north suppresses the moisture back to the south.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 605 PM MDT Fri Jul 26 2024
Isolated to scattered storms will continue this evening with
gusty outflow winds, small hail and brief heavy rain possible,
reducing conditions to MVFR at times. Most activity should
lessen by sunset with some nocturnal convection possible across
the north overnight. Expect redevelopment of thunderstorms,
favoring the higher terrain, Saturday afternoon with potential
drift into lower elevations late in the day.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...KAA
LONG TERM...KJS
AVIATION...TGJT
Area Forecast Discussion
National Weather Service Houston/Galveston TX
649 PM CDT Fri Jul 26 2024
...New AVIATION...
.SHORT TERM...
(This evening through Saturday Night)
Issued at 246 PM CDT Fri Jul 26 2024
The heavier rains of this morning have yielded to a "cool" and
cloudy afternoon featuring scattered showers. Temperatures are
fighting to surpass 80 degrees in some areas. A typical late July
afternoon ranges from low 90s near the coast to mid/upper 90s
inland. So the mid 70s to low 80s we are experiencing today could be
described as "cool" in relative terms. Perhaps we will establish a
few record low max temperatures today. The current shower activity
is expected to diminish as the late afternoon progresses into the
evening.
A well defined mid/upper trough can be seen over Texas via WV
imagery and 500MB RAP analysis. SE Texas is located between the
trough to our west and a mid/upper ridge over Florida. Moist
Tropical Pacific oriented SW flow aloft between the two features is
pushing a continuous stream a mid-level shortwaves up the Texas
Coast. These features in the upper-levels combined with deep LL
tropical moisture and some modest instability will keep the chance
of scattered to widespread showers and thunderstorms in the forecast
for your Saturday. Models indicate increasing PVA tonight into
tomorrow morning. However, there is some disagreement on the timing
of when lift becomes sufficient for shower/thunderstorm development.
Global models suggest we could have showers/storms develop across
our coastal counties as early as midnight. But hi-res CAMs guidance
suggest it may take until the pre-dawn hours before we begin to see
showers and thunderstorms develop. Though most of the CWA has a shot
at receiving rainfall on Saturday, the best chance of receiving
moderate to heavy showers and thunderstorms will be across our
southern and coastal counties during the morning hours. Considering
the saturated antecedent soil conditions, we have opted to extend
the Flood Watch through early afternoon tomorrow across our southern
and coastal zones. Saturday afternoon may end up like today with
overcast skies and scattered residual showers. Afternoon highs are
expected to be in the low/mid 80s. But we cannot rule out some areas
struggling to reach 80 again due to rainfall.
The pattern eventually becomes hotter and less rainy. But I`ll leave
that part of the discussion to the long range forecaster.
Self
&&
.LONG TERM...
(Sunday through next Thursday)
Issued at 246 PM CDT Fri Jul 26 2024
The transition to a more typical summertime pattern will begin on
Sunday as the robust midlevel trough in place across the South
Central CONUS will finally begin to shift to the northeast. Steady
rainfall should begin to taper off on Sunday morning as this
occurs, and over the course of the day broad surface high pressure
will once again become situated across the Eastern Gulf. The
resultant onshore flow regime promoted by this pattern, along with
the presence of a mid/upper ridge that will build into the central
third of the country by Monday morning, will result in decreased
rainfall chances over the course of the upcoming week given the
lack of available synoptic forcing. Rainfall chances through mid-
week will be confined mainly to diurnal heating, as well as the
inland propagation of the sea/bay breezes each afternoon. Have
generally maintained 20-40% PoP values in this forecast package,
with the highest rain chances concentrated along and south of the
Interstate 10 corridor. Rain chances decrease further towards the
end of the week with high pressure solidly overhead.
As one may expect with the transition to a more typical summertime
pattern, temperatures will steadily increase heading into next
week with highs returning to more normal values (mid-90s). With
onshore moisture transport once again keeping dew points elevated,
we could be looking at Heat Index values near 110 and thus will
need to monitor for the potential for Heat Advisories during this
time.
&&
.AVIATION...
(00Z TAF Issuance)
Issued at 637 PM CDT Fri Jul 26 2024
Still seeing some scattered rains across the area at this time, with
the bulk of the activity along and north of the I-69/US-59 corridor.
Will be expecting coverage to decrease through this evening with the
VFR ceilings likely falling into the MVFR/IFR range by sunrise. But,
another issue by sunrise could be the next round of showers/thunder-
storms developing and moving in from the SW. The best chances for TS
should be from IAH south to the coast from tomorrow morning into the
afternoon. 41
&&
.MARINE...
Issued at 246 PM CDT Fri Jul 26 2024
Periods of rain, heavy at times, will impact the coastal waters on
both Saturday and Sunday during the earlier parts of the day. Any
stronger storms may produce strong wind gusts and locally elevated
seas. Rainfall chances diminish on Monday as high pressure settles
into the area, promoting the return of a steady onshore flow
regime. Winds and seas should generally remain below caution
thresholds over this time.
Cady
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 73 83 73 87 / 30 50 20 60
Houston (IAH) 74 83 75 87 / 50 70 40 70
Galveston (GLS) 77 86 80 86 / 60 80 50 60
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch through Saturday afternoon for TXZ200-213-214-226-
227-235>238-300-313-335>338-436>439.
GM...None.
&&
$$
SHORT TERM...Self
LONG TERM....Cady
AVIATION...41
MARINE...Cady
Area Forecast Discussion
National Weather Service Indianapolis IN
937 PM EDT Fri Jul 26 2024
.KEY MESSAGES...
- Slightly warmer Saturday with increased cirrus clouds
- Increasing rain chances Sunday
- Increasing threat for multiple storm clusters to impact the region
next week
&&
.FORECAST UPDATE...
Issued at 935 PM EDT Fri Jul 26 2024
Fair weather will be the rule overnight as broad surface high
pressure centered over far southeastern Ontario continues to prevail
over most of the Midwest. A dry column will promote rain-free
conditions while allowing only cirrus clouds...which will be FEW in
number north of a Terre Haute to Seymour line, closer to the slowly-
departing ridge. Light winds spilling out of the high will
continue to prevail from generally easterly directions, although
flow will likely go variable by pre-dawn hours for most sheltered
and low-lying areas.
Decreasing dewpoints are expected to outrun any potential for
patchy fog formation. Below normal minimum readings tonight will
range from the mid-50s in Fishers and to points north/east...to
the low 60s inside Interstate 465 and across most areas to the
south/west.
Grids and update out.
&&
.SHORT TERM (This evening through Saturday)...
Issued at 227 PM EDT Fri Jul 26 2024
Various satellite products show western wildfire smoke at minimal
magnitude and most concentrated west of us over Illinois, near the
base of an upper level trough. So, minimal obscuration is currently
being observed. Trajectories and HRRR smoke model suggest minimal if
any haziness will be observed through the short term period, as most
of the smoke will be relegated to the polar jet at higher latitudes
in Canada.
Diurnal cumulus will diminish this evening with loss of surface
diabatic heating. Meanwhile, amplification of ridge of subtropical
jet will result in increased cirrus coverage through tomorrow. With
increased ridging will come slightly warmer temperatures, to about
late July climatology (mid-upper 80s).
Some diurnal cumulus is again expected tomorrow. Richer moisture per
IVT plots will hold to our southwest through the day tomorrow,
though high-level moisture will increase downstream of Plains upper
low, further enhancing cirrus coverage.
&&
.LONG TERM (Saturday night through Friday)...
Issued at 227 PM EDT Fri Jul 26 2024
Saturday Night Through Tuesday.
Quiet weather is expected for the start of the long term period, but
conditions are expected to become active through much of next week
as ridging across the Ohio Valley breaks down and the pattern favors
northwesterly flow as the ridge across the Rockies builds. Ahead of
the northwesterly flow, rain chances begin to increase going into
Sunday as a weak trough interacts with the moist airmass to bring
scattered showers and a few thunderstorms Sunday afternoon. Isolated
showers are expected to persist through early Monday with a fairly
stagnant airmass in place but by Monday night the aforementioned
northwesterly flow aloft will begin to dominate the weather pattern.
The first threat for ridge-riding thunderstorms will be Monday night
into early Tuesday with fairly good model agreement in potential
impacts to Indiana but with only marginal shear, not expecting a
high severe threat with a strong cold pool looking unlikely. This
may set the table though for potential flooding later into the week
if successive storm complexes further impact the same area.
Wednesday Through Friday.
The next most likely potential for a storm complex will be
Wednesday, but there remains quite a bit more model uncertainty as
to whether this system would impact Indiana. This system is more
likely to occur during the late afternoon through early evening
hours which should allow for a more organized thunderstorm complex
with much better shear and instability compared to the storms
earlier in the week. This system if it ends up impacting Indiana
has the potential for both damaging winds and isolated flooding.
There could be additional rounds of storms Thursday into Friday but
this will all be dependent on how the mesoscale environment is
impacted by the storms earlier in the week with low confidence on
even the synoptic environment by Friday as models rapidly diverge.
What does look likely is between Friday and Sunday, a more organized
upper level low should drop southeast from Canada with impacts to
the general Great Lakes Region.
Confidence in temperatures towards the middle to end of next week
begins to fall off with the general pattern favoring temperatures
near 90, but overnight convection may leave cloud debris which could
cause for some days to end up closer to 80.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 713 PM EDT Fri Jul 26 2024
Impacts: None
Discussion:
VFR conditions to continue through Saturday evening as central
Indiana remains under the southwestern portions of broad surface
high pressure aligned from the southern Great Lakes to the Jersey
shore. SCT/BKN cirrus should stay mainly south/west of terminals
through midday Saturday...before returning northeastward during
the afternoon.
Generally east-northeast winds will be light if not variable
tonight...before veering to more east-southeasterly flow Saturday
morning albeit continued light.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...AGM
SHORT TERM...BRB
LONG TERM...White
AVIATION...AGM
Area Forecast Discussion
National Weather Service San Francisco CA
849 PM PDT Fri Jul 26 2024
...New UPDATE, MARINE...
.SYNOPSIS...
Issued at 305 AM PDT Fri Jul 26 2024
Temperatures cool down more significantly beginning today with
below average temperatures to persist through mid next week. Some
potential for light drizzle along the coast Friday into Saturday
and Saturday into Sunday.
&&
.UPDATE...
Issued at 844 PM PDT Fri Jul 26 2024
Satellite imagery shows stratus building into the North Bay
valleys, the northern San Francisco Bay, the Monterey Bay region,
and into the Salinas Valley. Expect further stratus development
through the night with the Fort Ord profiler now showing a marine
layer over 2000 feet deep. Stratus will pare back to the coastal
regions during the morning, but could persist all day in the
western half of marin County, the northern San Francisco Bay
(including the city of San Francisco and Oakland), and the
southern Monterey Bay. The forecast remains on track with no
updates necessary.
DialH
&&
.SHORT TERM...
(This evening through tonight)
Issued at 1254 PM PDT Fri Jul 26 2024
Temperatures look to peak in the mid-to-upper 90`s across the far
interior, 70`s and 80`s around the South Bay and North Bay valleys,
and upper 50`s to 60`s near the coast this afternoon. Tonight,
expecting more widespread low clouds, fog, and coastal drizzle to
impact the region as the marine layer deepens. This is in response
to a mid/upper level trough moving across the region. Minimum
temperatures are forecast to be in the upper 40`s across the colder
interior spots with 50`s elsewhere.
&&
.LONG TERM...
(Saturday through Thursday)
Issued at 305 AM PDT Fri Jul 26 2024
Temperatures continue to cool Saturday and Sunday with widespread
70s to 80s expected inland and 60s to 70s expected closer to the
coast. Upper level troughing will continue to deepen over the
weekend which will help to keep temperatures cooler and contribute
to some slight potential for light drizzle. Overnight Friday into
Saturday and Saturday into Sunday, decent low level moisture at
850mb and 700mb will support the development of light drizzle to
light rain along the coast and in areas where upslope ascent is
favored. Both the NBM and the HRRR pick up on light coastal drizzle
overnight this weekend with some potential for light showers over
the marine environment. The NBM is showing very light precipitation
totals along the coast and bay shoreline with totals ranging from a
trace to a few hundredths of an inch.
The upper level pattern will become more zonal by early next week
which will allow for temperatures to warm slightly. In general,
temperatures are expected to gradually increase a few degrees each
day beginning Monday but high temperatures will still remain below
average through mid-week. By mid to late next week, a little more
uncertainty enters the forecast in regards to how fast high
temperatures will warm up again. Ensemble guidance indicates ridging
will start to build over the Western US by mid to late next week but
cluster analysis indicates that it is less certain where exactly the
ridge will set up. Temperatures could be slightly warmer depending
on if the ridge is centered more directly over the West Coast vs
temperatures could be slightly cooler if the ridge is centered to
the east of the coast. Regardless, it is looking likely that above
average temperatures will return with the current forecast and the
CPC 8-14 day outlook both in support of slightly above average
temperatures returning by the first week of August.
&&
.AVIATION...
(00Z TAFS)
Issued at 511 PM PDT Fri Jul 26 2024
LIFR/IFR CIGS are affecting the immediate coast and will fill over
the Monterey Bay and SF Bay terminals later this evening as winds
reduce. CIGs continue to move inland overnight, affecting the
remainder of the TAF sites. Winds are expected to stay light to
moderate overnight, with some pockets of mist and fog forming in
areas with the lightest winds. CIGs erode in the more inland areas
in the mid morning, while the Monterey Bay sees clearing in the
afternoon, however cloud cover looks to remain over the SF Bay for
the remainder of the TAF period.
Vicinity of SFO...Breezy winds reduce in the evening as IFR CIGs
arrive. Expect these CIGs and moderate winds through the night and
into Saturday morning. CIGS lift to MVFR levels into Saturday
afternoon as breezy westerly winds arrive. CIGs are expected through
the rest of the TAF period.
SFO Bridge Approach...Similar to SFO, with some chances of spotty
IFR-level cloud cover early Tuesday morning.
Monterey Bay Terminals...LIFR/IFR CIGs and mist push inland this
evening and last until the late morning before lifting, and eroding
into the afternoon as breezy winds arrive. CIGs move inland again in
the late afternoon on Saturday, Filling over MRY.
&&
.MARINE...
(Tonight through next Thursday)
Issued at 844 PM PDT Fri Jul 26 2024
Moderate to breezy Northwest winds linger through the weekend
before easing into the next work week. Expect some hazardous gusts
in the northern outer waters as well as along the Big Sur Coast.
Significant wave heights will continue to abate through the
weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Saturday for SF Bay N of Bay
Bridge.
Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Pt Pinos
to Pt Piedras Blancas 0-10 nm.
Small Craft Advisory until 3 AM PDT Sunday for Pt Arena to Pt
Reyes 10-60 NM.
Small Craft Advisory until 3 AM PDT Saturday for Pigeon Pt to Pt
Pinos 10-60 NM.
&&
$$
SHORT TERM...RGass
LONG TERM....Kennedy
AVIATION...Murdock
MARINE...Murdock
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Area Forecast Discussion
National Weather Service Spokane WA
320 PM PDT Fri Jul 26 2024
.SYNOPSIS...
Friday through the weekend will be mostly dry with near average
temperatures. A weather system arriving Monday and Tuesday will
bring a chance for some showers and thunderstorms in the Inland
Northwest. Dry and hot weather returns later next week.
&&
.DISCUSSION...
Today: Northwest flow aloft and lower heights continue to bring
more comfortable temperatures to the area. Winds across the area
are light, which should help to reduce some smoke production.
Nonetheless, the HRRR smoke shows a swath of smoke from the
Swawilla fire migrating towards the Colville area this evening and
overnight. The fires near Juliaetta are sending smoke to the
southwest and the Lewiston has cleared out a bit.
Saturday and Sunday: A closed low off California moving inland
will help to maintain lower heights across the area, while an
approaching shortwave will move across the area, bringing tighter
pressure gradients and increased winds across central Washington
on Saturday and central and eastern Washington Sunday. There is a
20-40% chance of meeting red flag conditions near Wenatchee and
the L-C valley Saturday and Sunday. There is a 10-20% chance of
thunderstorms in the north Cascades/northern mountains Saturday as
model soundings show weak conditional instability building with
the shortwave passage.
Monday and Tuesday: Another stronger shortwave trough from the Gulf
of Alaska will move onshore late Monday into Tuesday, bringing
tighter pressure gradients and stronger associated winds,
elevating fire concerns despite higher humidities. Associated with
this is a chance for wetting rain approaching 50% northeast of
Spokane and in the Cascades/Idaho Panhandle Monday through Tuesday
night, as well as a 10-20% chance of lightning. Unfortunately,
central Washington is unlikely to see a wetting rain during this
time, and as wind increases, fire concerns will be elevated with
the very dry fuels. Nonetheless, increased cloud cover and
humidity will aid fire-fighting efforts. Temperatures will remain
near-average during this period.
Wednesday through Friday: Models are in good agreement that a
ridge will start to build back in later next week, which will
bring increasing heat to area, with high temperatures approaching
the mid-90s to low-100s. Winds will abate to below critical levels
during this period, but associated dry air and increased heat will
still likely allow for fire risk levels to remain at or near
levels seen earlier in the week. /Cooke
&&
.AVIATION...
00Z TAFS: Dry northwest flow aloft will keep conditions VFR
through the period with light and diurnally/terrain driven winds.
Smoke from local and regional wildfires wildfires may result in
intermittent visibility reductions to 6SM. The exception will be
for KLWS where nearby fires (River and Gwen) to the east will
result in reductions to 4SM or less, bouncing between MVFR and IFR
conditions. Northwest winds in the afternoon may slightly improve
conditions but confidence is low.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is low
confidence on how smoke will impact visibility across the Inland
Northwest.
-----------------------
Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70
percent chance
High - Greater than a 70 percent chance
For additional probabilistic information for NWS Spokane airports,
please refer to the Aviation Dashboard on our webpage:
https:/www.weather.gov/otx/avndashboard
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 53 87 56 86 59 84 / 0 0 0 0 0 10
Coeur d`Alene 51 85 54 84 57 81 / 0 0 0 0 0 10
Pullman 47 82 50 81 52 82 / 0 0 0 0 0 0
Lewiston 59 92 61 92 65 91 / 0 0 0 0 0 10
Colville 44 84 45 84 47 82 / 0 10 10 0 0 30
Sandpoint 47 82 50 82 52 78 / 0 0 0 0 0 20
Kellogg 55 80 57 80 59 79 / 0 0 0 0 0 10
Moses Lake 53 89 55 89 57 87 / 0 0 0 0 0 10
Wenatchee 61 88 61 88 64 84 / 0 0 0 0 10 20
Omak 58 91 58 91 60 86 / 0 10 10 0 0 30
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Pendleton OR
425 PM PDT Fri Jul 26 2024
Updated aviation discussion
.SHORT TERM...Tonight through Sunday night...Satellite imagery
reveals widespread smoke and haze across most of eastern Oregon
and eastern Washington, the result of regional wildfires which
continue to burn. Have extended smoke and haze in the forecast
through Sunday morning based primarily on HRRR smoke output.
While smoke and haze will likely linger across the region,
especially in the vicinity of ongoing wildfires, have opted to
exclude mention in the gridded forecast due to uncertainty in the
evolution of fires and smoke output.
Weak troughing over the Pacific Northwest will keep near-normal
temperatures and locally breezy westerly gap winds in place this
weekend. Saturday, a weak disturbance tracking across southeast
Oregon will bring non-zero, but low (<5%) chances of showers or
thunderstorms across the southern Blue Mountains during the
afternoon. A concurrent shortwave tracking across northern
Washington appears mostly dry with the main consequence being the
wind.
.LONG TERM...Monday through Friday...Models continue to be in good
agreement in having a trough over the Pacific Northwest with a
ridge over the central CONUS Monday and Tuesday. Tuesday afternoon
into Wednesday, a front moves through the area and carries the
trough eastward while closed low develops out in the eastern
Pacific. Models show general agreement in having a westerly zonal
flow overhead Wednesday though about 40 percent of model ensemble
cluster members begin having the ridge building into our area.
Thursday and Friday, model ensemble members all have the ridge
building and strengthening over our area with temperatures warming
well above normal to around 100 degrees by Friday.
The Extreme Forecast Index highlights Precipitation amounts along
the Washington Cascades Monday and Tuesday with values of
0.72-0.82 and some shift of tails values indicating a
possibility of heavier rain. It also highlights breezy winds
Monday afternoon in central Oregon and portions of the Columbia
Basin with a value 0.73. Cooler than normal temperatures are
highlighted Monday and especially Tuesday due to cooler air with
the front.
Monday will see the trough coming ashore with a slight chance to
chance of showers developing the Cascades in the late morning and
afternoon then spreading into the rest of the area Monday night.
The Cascade crest could get up to a half of rain but amounts
will be fairly light away from the crest. Models are not showing
enough instability for thunderstorms and the timing may be too
late (evening) for convection in the eastern mountains, so just
have showers. With the front, winds will increase to 10 to 20 mph
over most of the area. Model probabilities show a 25-55 percent
chance of 20 mph sustained winds, but chances of 25 mph sustained
winds drop to below 15 percent and that is just in the Columbia
Gorge and Kittitas Valley. Temperatures Monday will be similar to
Sunday with highs in the mid 80s to around 90 in the lower
elevations.
Tuesday will see the trough overhead and then moving off to the
east Tuesday night. This will be a more favorable day for
showers and a slight chance of thunderstorms in the eastern
mountains though amounts will be just a few hundredths of an inch
for the most part. Showers and thunderstorms will end quickly in
the early evening. The Columbia Basin will again have 10 to 20 mph
winds but winds will be lighter in central Oregon. Temperatures
will drop a few degrees to the lower to mid 80s with 70s in the
mountains.
With ridging beginning to develop Wednesday, foresee dry weather
and light winds with temperatures warming to near normal in the
upper 80s to lower 90s. The ridge will strengthen further Thursday
with temperatures rising to the mid to upper 90s and in the mid
80s to lower 90s in the mountains. NBM probabilities show a 20-35
percent chance of reaching 100 degrees in the Columbia Basin,
central Oregon and in the John Day valley.
On Friday, the cutoff low that has been parked out in the eastern
Pacific moves closer to the coast and our flow turns more
southerly and unstable due to a possible ridge breakdown. There
is some chance that this situation could pull some moisture into
the area and PWATs are over an inch in the GFS, but at this time
models are holding off on any showers or thunderstorms. It looks
more favorable next Saturday but that is past the scope of the
long term forecast. This will have to be watched during the course
of next week. Temperatures will warm further with highs rising to
97-105 in the lower elevations and mainly in the 90s in the
mountains. NBM probabilities give a 40-70 percent chance of
reaching 100 degrees, but the chances of 110 degrees are less than
5 percent even in the warmest locations. Perry/83
&&
.AVIATION...00Z TAFs...VFR conditions with mainly clear skies will
prevail through the night then expect some increasing high clouds on
Saturday. However, there will be considerable haze and smoke aloft
and some reduced visibilities produced near many of the ongoing
fires. Continue to expect YKM to have vsbys down to around 4SM
overnight in HZ and FU with some possible improvement on Saturday.
KBDN could also see a return of some SCT-BKN around 040 overnight
through Saturday morning. Winds will be less than 10 kts overnight.
KDLS will see winds increasing after 15Z tomorrow to 15-20 kts and
gusts around 30kts.
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 51 86 56 87 / 0 0 0 0
ALW 54 89 60 90 / 0 0 0 0
PSC 56 91 61 91 / 0 0 0 0
YKM 53 89 55 89 / 0 0 0 0
HRI 54 91 60 90 / 0 0 0 0
ELN 56 87 57 86 / 0 0 0 0
RDM 47 86 48 85 / 0 0 0 0
LGD 51 86 51 87 / 0 0 0 0
GCD 51 88 51 88 / 0 0 0 0
DLS 58 86 61 85 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&
$$
SHORT TERM...86
LONG TERM....83
AVIATION...83
Area Forecast Discussion
National Weather Service Pocatello ID
234 PM MDT Fri Jul 26 2024
.SHORT TERM...Tonight through Saturday Night.
Early afternoon satellite imagery shows a departing cold front
over the WRN Great Plains as a H5 trough shifts over the PacNW and
NRN Rockies, bringing with a drier and cooler airmass in addition
to increased wildfire smoke regionwide. Even given this drier
environment in place today, PWATs around 0.50-0.80" will support
isolated to scattered shower and thunderstorm development across
ERN Idaho with the HREF model showing a 20-60% chance of thunder
along and east of I-15 into Wyoming with less than a 20% chance
elsewhere. The convective environment today will support around
800-1200 J/kg of SBCAPE, 1000-1500 J/kg of DCAPE, 20-30 kts of 0-6
km shear, and 8- 9 degree/km 700-500 mb lapse rates. This
environment will support strong thunderstorms that will be capable
of producing wind gusts to 40-60 mph, small hail, and brief heavy
rain. Highs today will be in the 80s to low 90s with breezy
synoptic winds supporting gusts to 20-40 mph.
A H5 low off the coast of NRN California this afternoon will move
onshore tonight into Saturday and as it does, pick up a plume of
monsoon moisture along the way. This moisture will build into SE
Idaho starting Saturday morning with isolated to scattered showers
and thunderstorms possible during the morning hours SE of the
Snake Plain. These shower/thunderstorm chances will expand
regionwide by the afternoon hours with the HREF model showing a
40-90% chance of thunder across our entire CWA with an emphasis on
a 70-90% chance across the Snake Plain into Montana, Wyoming, and
Utah. In similar fashion to today, the convective environment
Saturday will support 300-800 K/kg of SBCAPE, 1000-1500 J/kg of
DCAPE, 25-35 kt 0-6 km shear, and 7-9 degree/km 700-500 mb lapse
rates. This environment will again support strong outflow wind
gusts in that 40-60 mph range (locally stronger), small hail, and
heavy rain. In addition, the SPC has outlined much of our region
in a MARGINAL RISK (5-14% chance) of severe thunderstorms across
much of SE Idaho for Saturday. Shower and thunderstorm coverage
will drop after sunset with isolated activity lingering around the
Yellowstone/Grand Teton NP region. Highs Saturday will be in the
70s and 80s which will mark the coolest day in our region since
July 4th given this system`s passage. MacKay
.LONG TERM...Sunday through next Friday.
Sunday, expect southwest flow aloft as a weak wave passes well
north of our area. Expect breezy winds on the surface with gusts
of around 20 to 30 mph along with isolated, mostly afternoon
mountain thunderstorms. Temperatures will be around normal on
Sunday. Expect breezy southwest flow aloft to continue on Monday
bringing afternoon gusty conditions. Little to no thunderstorms
are expected on Monday. Temperatures look to rise slightly above
normal on Monday. Tuesday into Wednesday models show a weak wave
move through the area bringing breezy winds and mostly isolated
thunderstorms. Temperatures look to drop down to normal to
slightly below normal on Tuesday and Wednesday.
Late Wednesday into late next week high pressure builds back into
the area. Expect dry and hot conditions Thursday and Friday.
Temperatures will be 8 to 12 degrees above normal with lower
elevations in the mid to upper 90s. A few areas may hit 100
degrees on Friday. Wyatt
&&
.AVIATION...For the 18Z TAFS through 18Z Saturday.
Expect VFR conditions and breezy winds this afternoon for all TAF
sites. Our area has breezy southwest flow aloft behind an exiting
cold front today. There is enough moisture and instability for
thunderstorms this afternoon, mainly in the mountains across our
east and southeast. Only have vicinity thunderstorms for KDIJ this
afternoon as the HREF model shows a 50 to 60 percent chance of
thunderstorms. Any thunderstorms on station could bring brief MVFR
conditions. The only other likely TAF site that may have
thunderstorm impacts is KPIH. There is a 20 to 30 percent chance
of thunderstorms for KPIH from the HREF model. However,
thunderstorms look to develop just southwest of KPIH over the
Portneuf mountains near Inkom this afternoon. Have held off on
vicinity thunderstorms for this afternoon for KPIH for now.
Saturday morning into Saturday afternoon, expect thunderstorm
impacts for all sites with a trough moving through southwest flow
aloft. Gusty outflow winds of around up to 35 to 50 mph are
likely. Gusts up to 60 mph are possible, especially for KBYI.
Thunderstorms on station are possible as well, especially for
KBYI, KPIH, KIDA, and KDIJ. Wyatt
&&
.FIRE WEATHER...
Following a departing cold front yesterday, RED FLAG WARNINGS
remain in effect for FWZ 410, 422, 475, and 476 for a combination
of low RH in the teens and wind gusts to around 25-40 mph. In
addition today, isolated showers and thunderstorms will be
possible across FWZ 410, 411, and 413 with an emphasis on stronger
storms supporting gusty outflow winds in that 40-60 mph range,
heavy rain, and frequent lightning.
For Saturday, another system rolls in from the Pacific and as a
result we have gone ahead with RED FLAG WARNINGS for all zones
outside of 422 for a mix of scattered wet and dry thunderstorms
which will go in effect from 1200 to 2200 everywhere outside of
FWZ 413 which will be from 0600 to 2200 given the threat of
morning convection. Again, stronger storms will support gusty
outflow winds in that 40-60 mph range, heavy rain, and frequent
lightning but given PWATs around 0.50-0.80" range, the potential
for isolated dry thunderstorms will exist.
Following this systems exit to our NE on Sunday, isolated to
scattered showers and storms will linger in 410, 411, 413, 427,
and 476 but coverage will drop across our region in comparison to
Saturday. High pressure begins to build into early next week as a
H5 trough passes over the NRN Rockies on Tuesday. As a result,
conditions will remain mostly dry early next week outside of
isolated showers and storms in Lemhi County with the primary focus
on elevated winds peaking each afternoon which will support near
critical to critical fire weather conditions given RHs in the
teens and 20s. Following the exit of that trough, a H5 ridge axis
will shift overhead and will lead to a warming trend through next
week as conditions return to being very dry. MacKay
&&
.AIR QUALITY...
The HRRR smoke model shows a large plume of smoke from Oregon and
California wildfires as well as a large wildfire about 50 miles
south of Mountain Home working through through our area today.
Meanwhile smoke from the Bench Lake Fire will overspread much of
the Central mountains. Air quality in our northwest areas, Eastern
Magic Valley, Shoshone, northern Arco desert, and southern Snake
Plain fell to the "unhealthy" stages today. There are multiple Air
Quality advisories out including Cassia, Lincoln, Minidoka,
Custer, and Butte counties. There will likely be additional
counties added to the Air Quality advisories today.
Wildfire smoke will likely hang around through the weekend and
possibly into early next week across the Snake Plain, Magic
Valley, Lower Snake plain, and Central mountains. There could be
some improvement Saturday afternoon across eastern Idaho as storms
develop. These storms will allow for vertical mixing and may
temporarily clear the atmosphere for a few hours. Expect continued
degraded air quality on Sunday with less confidence heading into
early next week. Wyatt
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 10 PM MDT Saturday for IDZ410-411-
425-427-475-476.
Red Flag Warning until 10 PM MDT this evening for IDZ410-422-475-
476.
Red Flag Warning from 6 AM to 10 PM MDT Saturday for IDZ413.
&&
$$
Area Forecast Discussion
National Weather Service Reno NV
126 PM PDT Fri Jul 26 2024
.SYNOPSIS...
* Isolated storms for portions of western NV this evening and
overnight. Winds will remain gusty through Saturday across
ridges.
* Gusty southwest winds and lower humidity bring increased fire
weather concerns to northeast CA and northwest NV this afternoon.
* Dry conditions and more seasonal temperatures will prevail this
weekend through the remainder of July although smoke may spread
across portions of northeast CA and western NV.
&&
.DISCUSSION...
* THUNDERSTORMS: Confidence remains unchanged (medium) as HREF
showed a decrease in the 40 dBZ echo potential overnight, but
maintains a convective signature for elevated and quick moving
clouds/showers starting along and south of US-50 late this
afternoon or early evening and lifting northward into the late
evening and early morning hours Saturday. Latest satellite
imagery showed cumulus development beginning over southern Mono
County which may lead to a few cells through 5 PM before best
focus shifts eastward into NV this evening. Gusty outflow winds
to 35+ kts will be a threat with any shower or storm that
develops with a 10-20% chance for seeing lightning. We
maintained a 5-10% chance as far west as Hwy 395.
* WINDS: Gusty southwest winds will continue into this evening,
especially along Hwy 395 and across NE CA/NW NV with most gusts
25-30 mph, but locally as high a 35 mph for a few hours. As a 70
kt 250 MB upper jet moves across the Sierra, winds will ramp up
over the ridges and upper slopes with gusts 50+ mph (locally to 70
mph at the typical windiest spots). While winds will decrease at
lower elevations, they may remain elevated on Lake Tahoe and
across foothill locations overnight and Saturday AM behind the
exiting shortwave.
* SMOKE: Satellite and Alert cams indicate smoke across parts of
northeast CA and northwest NV from wildfires (primarily the Park
and Stockade Canyon wildfires) this afternoon. As winds turn
back to more west-southwest behind tonight`s shortwave, HRRR
indicates this smoke drifting farther south into western NV this
weekend, possibly impacting areas as far south as Fallon and
Reno by Sunday/Sunday night.
* NEXT WEEK: After seasonal temperatures through the end of July,
there are indications that the ridge will build near the Four
Corners and expand westward into the Great Basin per latest
ensemble clusters. This pattern would likely return temperatures
to 10 degrees above average with 100+ degrees across western NV
as we go into August. Also, the high`s position would bring a
return southerly flow and increasing risk of thunderstorms.
Hohmann
&&
.AVIATION...
* For late this afternoon/tonight, an upper level wave will bring
a 10-20% chance of storms across W NV, focusing east and north
of Reno. There is a 10-15% chance for storms at KMMH from 21Z to
00Z today with a 5% chance of storms at KRNO-KCXP-KMEV after
27/00Z. Storms may linger past midnight across NW NV as storms
lift northward.
* SW-W winds with gusts 20-25 kt across most of the main terminals
with gusts to 40 kt across the ridges through sundown. As a 70
kt 250 MB jet traverses the Sierra tonight/early Saturday, 700
MB winds will increase to 30-35 kts with gusts up to 60 kts at
ridge level. This will lead to increasing LLWS along the eastern
Sierra from the Tahoe Basin southward to Mammoth Lakes. Leeside
turbulence may increase to moderate at times along the eastern
Sierra into far western NV.
* Smoke and haze from local wildfires will produce areas of
reduced slantwise visibilities from Susanville to Gerlach and
points north, with high resolution models indicating this smoke
slowly shifting south toward I-80 in W NV this weekend.
Hohmann
&&
.FIRE WEATHER...
Afternoon west-southwest breezes to 25-30 mph and low daytime
relative humidity will lead to elevated fire weather concerns
areawide through this evening. Some areas across Lassen and northern
Washoe counties may see a few hours of critical fire weather
conditions, though this threat is too isolated spatially to warrant
the issuance of a Red Flag Warning today.
There is a slight chance for shallow nocturnal convection tonight,
roughly along and east of a line extending from eastern Mineral
County into far northern Washoe County. Isolated showers look to
initiate along this line following sunset before tracking
northeast and out of our region overnight. Thunderstorm chances
are low, but non-zero, with main concerns for gusty outflow winds
given steep low-level lapse rates.
Fire weather concerns diminish this weekend as the cooling trend
continues and overnight RH recoveries improve. For areas north of I-
80, dense smoke concentration from the Park Fire may further reduce
daytime heating and thus limit fire activity for new or existing
fires this weekend. Whitlam
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
Area Forecast Discussion
National Weather Service Riverton WY
448 PM MDT Fri Jul 26 2024
.KEY MESSAGES...
- Showers and thunderstorms are possible today, though
confidence on timing and location remains low as models
differ. Everywhere has at least a small of chance of rain
today, though.
- Showers and thunderstorms possible again Saturday, starting
mid-morning. Gusts up to around 50 mph are possible.
- A drying and warming trend begins Sunday, and especially into
the workweek. Fire weather concerns starting Monday.
&&
.DISCUSSION...
Issued at 1226 PM MDT Fri Jul 26 2024
The cold front that passed through yesterday has brought seasonal
temperatures across the area today, with highs generally in the 80s,
with low 90s for the warmer favored locations. The main story for
today is scattered showers and thunderstorms, aided by the passage
of a shortwave this afternoon. Models continue to be variable in
their timing and coverage of storms this afternoon and evening.
Would say there is at least a 15% chance of rain anywhere in the CWA
today, though there will be many locations that do get a storm.
Though some of this convection could come with locally heavy rain,
(favored more for southern half of the area) gusty winds are the
main threat. Gusts 30 to 40 mph should be common with any storms
that develop, with gusts near 50 mph a real possibility. Some small
hail is also possible with some of the stronger storms. Overall,
support is not looking good for any widespread severe storms. Models
are consistent in ending convection by midnight.
Another shortwave moves through Saturday, this time in the morning.
This should kick off showers and thunderstorms earlier than normal.
Southwest Wyoming sees rain chances pick up after 5am MDT. These
chances spread east-northeastward through the morning, with another
day of widespread rain chances over the area for the afternoon. Like
today, models are showing various locations, coverage, and timing of
convection Saturday, so confidence is low on those aspects of the
forecast. However, it will be another day where everywhere has at
least a small chance of a storm. Gusts to 50 mph will be the main
hazard of concern again. The recent HRRR has a few gusts over 50
mph as well.
A ridge starts to build in from the south Sunday. This keeps the
best afternoon rain chances over the northern half of the area.
Otherwise, highs continue to be seasonal through Sunday. The ridge
continues to build in through next week. Temperatures climb a
little, with dry air returning. This increases fire weather concerns
starting Monday. The chance of any showers and thunderstorms also
remains very low for next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 447 PM MDT Fri Jul 26 2024
Scattered rain showers and thunderstorms will wind down this
evening. Unless a thunderstorm moves directly over a terminal
conditions will be VFR, although smoke will move in today, so
reductions in VIS due to smoke/haze will occur at times, especially
for northern terminals KCOD/KWRL. For now have not included FU in
this TAF issuance due to uncertainty in how quickly it mixes down to
the surface.
An area of rain showers is likely (80%) to move through central
Wyoming Saturday morning, so have included -SHRA at
KBPI/KPNA/KLND/KRIW as this area of rain showers moves through. More
convection will develop Saturday afternoon, although it looks more
isolated, so only PROB30 groups at KRKS and KCPR. It will be breezy
at most terminals beginning late Saturday morning.
Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
Air Quality Alert from midnight tonight to 1 PM MDT Sunday for
WYZ001>013.
&&
$$
DISCUSSION...Wittmann
AVIATION...Rowe
Area Forecast Discussion
National Weather Service Las Vegas NV
754 PM PDT Fri Jul 26 2024
.SYNOPSIS...Isolated showers and thunderstorms expected for one
last afternoon today across the southern Great Basin and
northwestern Arizona before dry air pushes into the region this
weekend. Temperatures will moderate closer to seasonal averages
before gradually increasing once again through the work week.
Breezy west to southwest winds are expected this weekend which
will increase for danger, especially Saturday. Precipitation
chances return to Mohave County by midweek as monsoon moisture
returns.
&&
.UPDATE...The few thunderstorms that developed in what`s left of the
monsoon moisture over far eastern Mohave County have already
dissipated. Finally did get some thunderstorms to develop around and
north of Tonopah. Instability is quite limited in that area with
CAPE values 100-150 J/kg, but the shear profile is much better with
Sfc-6km Bulk Shear of 40 kts. HRRR indicates storms in this area
will dissipate by late evening.
Otherwise, air quality will be impacted by wildfires in Kern and
Tulare Counties. The Borel Fire, northeast of Bakersfield was very
active today with satellite showing dense smoke plume being
transported across southern Inyo County, Death Valley NP, southern
Nye into far western Lincoln Counties. Will send out an evening
update with updated smoke/haze grids for the rest of
tonight/Saturday based on the latest HRRR Smoke output.
&&
.PREV DISCUSSION...102 PM PDT Fri Jul 26 2024
.SHORT TERM...Tonight through Sunday.
Moisture will continue to decrease tonight into Saturday as an upper
level shortwave pushes through the region and shifts the flow to a
dry west or southwesterly direction. By Saturday morning, the
probability for over 1.00 inch PWAT is below 20% areawide. This dry
air will stick around through the weekend as PWATs drop to 30%-50%
of normal for this time of the year. No precipitation chances are in
the forecast for any locations through Sunday.
Breezy southwest winds are expected this weekend as the pressure
gradient increases with the passing upper level system. Saturday
will be the windiest day with widespread gusts of 20-30 MPH,
especially through that typical southwesterly wind belt from
Barstow, CA through Las Vegas, NV through Colorado City, AZ. The
probability for impactful winds over 40 MPH is low (20% or less),
however fire danger will increase as there will be significant dry
air entrenched over the region. The highest risk for wildfire spread
will be in Arizona Strip where winds over 20 MPH will combine with
low relative humidity, along with recent fire starts which may
compound issues. In southern Mohave County winds may not be as
strong but they will still be elevated and the risk for fire starts
will be high because of dry conditions and the amount of recreation
that goes on in the area over the weekends. Issued a Red Flag
Warning for much of MOhave County for Saturday due to the overall
heightened risk and at least near-criteria conditions. Elsewhere,
anyone with outdoor plans that would involve activities that
increase fire starts like camping or traveling with chains on cars
should use caution. Winds on Sunday will not be as strong as
Saturday as the upper level system begins to move away from the
area, with gusts across the region topping out at 20-25 MPH.
As the trough moves through the Great Basin region over the weekend,
high pressure will be knocked down and the strongest heights will be
pushed out of the area. This will result in cooler temperatures as
temperatures fall to near normal for the first time in a while by
Sunday. Las Vegas has observed 36 consecutive days of temperatures
over 105 degrees as of yesterday. The previous record was 25 days in
2017. The current forecast calls for a high temperature of 104 on
Sunday, which will end the streak. Latest NBM probabilities show a
71% chance of Las Vegas reaching 105 or higher, with the
deterministic NBM on the cooler side of the box-and-whiskers for the
week. If Las Vegas reaches or exceeds 105 on Sunday, there will not
be another opportunity to break this streak through the remainder of
the forecast period.
.LONG TERM...Monday through Friday.
Period begins with a trough across the Pacific Northwest that
will maintain a southwest flow over the southern Great Basin and
Mojave Desert. This will keep the area dry along with seasonable
temperatures.
On Tuesday and Wednesday, the trough will begin to fill/weaken
allowing ridge which had been suppressed over the southern High
Plains to begin expanding westward. This will allow temperatures to
heat back up above normal along with increasing thunderstorm chances
returning to northwest Arizona Wednesday/Thursday, and potentially a
few hi-based storms west of the Colorado River over the higher
terrain of the Mojave National Preserve and Clark County
mountains.
&&
.AVIATION...For Harry Reid...Southwest winds with occasional gusts
to 25kts can be expected this afternoon and again on Saturday
afternoon. Winds will diminish slightly overnight tonight, but a
few gusts to 20kts will remain possible. Any afternoon convection
today will be limited to the Mormon Mesa and Peach Springs
corridors, and no storms are forecast on Saturday. Smoke from fires
over southern California will also move across the area today and
Saturday. While no significant reduction in surface visibilities is
expected, slantwise visibilities may fall below 7NM at times.
Otherwise, no operationally significant cloud cover is expected
through Saturday.
For the rest of southern Nevada, northwest Arizona and southeast
California...Only isolated areas of convection are forecast this
afternoon and evening, mainly over northwest Arizona. Southwest-
to- west winds will increase across the Mohave Desert this
afternoon, with gusts to 25kts possible in the Vegas Valley and
30kts near KDAG. Winds in the Colorado River Valley will generally
be southerly, around 25kts this afternoon. Near KBIH, light
southerly winds will turn westerly by late afternoon. Smoke from
fires over southern California will also move across the area
today and Saturday. While no significant reduction in surface
visibilities is expected, slantwise visibilities may fall below
7NM at times over southern Nevada and eastern California.
Otherwise, no operationally significant cloud cover is expected
through Saturday.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
SHORT TERM...Nickerson
LONG TERM...Pierce
AVIATION...Planz
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