Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/16/21
Area Forecast Discussion
National Weather Service Aberdeen SD
843 PM CDT Sun Aug 15 2021
.UPDATE...
Issued at 842 PM CDT Sun Aug 15 2021
Quiet night across the forecast area. Main feature is the amount
of smoke expected to move into the forecast area, especially west
river, overnight and tomorrow. Made a few minor changes to the
winds, otherwise forecast in good shape.
&&
.SHORT TERM...(This Evening through Monday Night)
Issued at 236 PM CDT Sun Aug 15 2021
A trough is moving southeast through North Dakota this afternoon. So
far, the boundary passage has been dry. CAMs solutions are keeping
this forecast area dry this evening. However, chances are likely non-
zero on showers or thunderstorms due to a llj east of the James
valley. Kept a precip mention out of the grids for now, but may need
to be added in if convection manages to bust the cap as the trough
stalls this evening.
As the trough settles into central SD, the airmass will be
significantly drier. On Monday, the min RH is expected to fall below
20 percent but shouldn`t align with the breezy southerly winds that
are forecast farther east. The south to southwest winds and llj will
keep the downslope effect going along the Prairie Coteau both
tonight and Monday night.
Temperatures will continue to warm under the upper ridge. However,
the HRRR smoke product shows the thicker smoke that is over Montana
today making its way into central SD behind the trough on Monday.
Along with some reduction in visibility, the smoke may inhibit highs
by 2 to 5 degrees holding temperatures below the 100 degree mark.
.LONG TERM...(Tuesday through Sunday)
Issued at 236 PM CDT Sun Aug 15 2021
The long term period begins with a couple of warm, but breezy days
on Tuesday and Wednesday. Highs on Tuesday could reach the 90s, to
the lower 100s along and west of the Missouri River. These readings
would be 10 to nearly 20 degrees above average for this time of
year. A deep upper level trough and surface frontal boundary may
begin crossing the region as early as Wednesday night-Thursday
morning as the GFS suggests, or Thursday night into Friday as the
ECMWF and Canadian indicates. Slight differences among deterministic
and ensembles causes a broad brush of pops Wednesday night and
perhaps into Thursday. Higher NBM pops is mostly confined to Thursday
night into Friday. Much cooler temperatures should move into the
region over the weekend, with highs 70s, to the low 80s. Depending
on model used, additional storms could be possible over the weekend
as well.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 606 PM CDT Sun Aug 15 2021
Terminals KABR,KATY,KPIR,KMBG
VFR conditions will prevail overnight. Smoke will increase in
coverage overnight with visibilities possibly falling to 3 miles
at KMBG and KPIR Monday.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Scarlett
SHORT TERM...Wise
LONG TERM...SD
AVIATION...Scarlett
Area Forecast Discussion
National Weather Service Bismarck ND
921 PM CDT Sun Aug 15 2021
.UPDATE...
Issued at 912 PM CDT Sun Aug 15 2021
The 00 UTC sounding at Bismarck showed enough of a cap between 600
and 500 mb to inhibit any thunderstorm development this evening.
Expect a warm and mostly clear but hazy/smoky overnight period
tonight. Smoke increases west to central on Monday both at the
surface and aloft. Adjusted smoke a bit based on latest model
forecasts and bumped it to areas of smoke instead of patchy.
Otherwise no changes from the previous forecast.
UPDATE Issued at 552 PM CDT Sun Aug 15 2021
Latest surface analysis depicts a weak surface low along the
International Border, north of Minot, with a surface trough/dry
line extending south into south central ND. Current temperatures
are mainly in the upper 90s to around 103. Heat indices are in the
100-105 range within the Heat Advisory. Will let this continue
through 7 PM as advertised.
There remains a small chance of thunderstorms, mainly east of the
Highway 83 corridor, within an area of strong instability with
MLCapes of around 2500-3500 J/KG and effective shear around 30
knots. Cumulus field over central ND has shown little in the way
of agitation, which is reasonable given the lack of an shortwave
and the warm air in place. a few small towers have developed and
quickly dissipated. If There we could get a sustained updraft a
cell could become quickly strong to severe given the instability.
The most likely location would appear to be around the Devils Lake
Basin into the northern James River Valley, within an area of
greatest instability and some weak surface moisture convergence.
Will keep a slight chance of storms through the early evening.
Otherwise no changes from the going forecast. Updated text
products will be sent shortly.
&&
.SHORT TERM...(This evening through Monday)
Issued at 123 PM CDT Sun Aug 15 2021
There are multiple forecast concerns over the short term.
For the rest of this afternoon and into the evening, a heat
advisory will be in effect as a combination of moist, southerly
flow and stronger ridging will lead to heat index values up to
105. Later this afternoon, there will be a slight chance for
thunderstorms across portions of south central into eastern North
Dakota. Confidence remains low as there is no obvious source of
lift, however storms were able to form under similar conditions
yesterday. Severe weather is not expected, but the strongest
storms will be capable of small hail and gusty winds given plenty
of CAPE and marginal effective shear values.
Meanwhile, smoke is expected to gradually filter into the area
from the west this afternoon, mainly effecting far western North
Dakota this afternoon and southwestern North Dakota overnight. The
HRRR smoke model is continuing to indicate another plume of smoke
pushing into much of western and central North Dakota late
tomorrow morning and early afternoon, so we will continue to
monitor. As of now, only patchy smoke is being mentioned in the
forecast for tomorrow with areas of smoke across the west this
afternoon.
Tomorrow afternoon, near critical fire weather conditions will
exist across western and portions of central North Dakota due to
the presence of slightly stronger downsloping westerly winds.
Otherwise, continued hot and dry conditions on Monday with at
least a couple sites likely breaking record highs.
.LONG TERM...(Monday night through Sunday)
Issued at 123 PM CDT Sun Aug 15 2021
Warm and dry conditions will continue through the first part of
the long term, with cooler temperatures and increased chances for
precipitation likely for the back half of the week.
The progression of the trough expected to enter the Pacific
Northwest early this week has continued to slow a bit amongst
guidance, with the ECMWF even forming a stationary cut off low
near the Great Basin. However, consensus is for the trough to
eventually reach the Northern Plains around mid week. Until then,
we can expect continuing near record high temperatures and dry
conditions.
The high temperatures on Wednesday will be highly dependent on the
timing of the trough and associated cold front, with a late
arrival resulting in another hot day for most. Precipitation
chances then increase Wednesday night into Thursday and linger
into the weekend. Highs beyond Wednesday are likely to be
seasonably cool in the upper 60s and 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 912 PM CDT Sun Aug 15 2021
Smoke will reduce visibilities west tonight and may spread into
central ND late tonight or Monday.
MVFR visibilities in smoke have developed at KXWA and KDIK. Hard
to tell how much lower vsbys will go or how long the lower vsbys
will last but based on smoke fcst, will keep a reduction in
smoke through Monday morning. For now will keep it in the 3-5SM
range and adjust as needed.
VFR ceilings are expected through the 00Z forecast period with
only some high thin clouds. However, there could be some
artificial ceilings indicated due to the smoke. A south to
southwest surface flow will remain over the area but turn more
westerly at KXWA, KDIK and KMOT Monday afternoon.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...Gale
LONG TERM...Gale
AVIATION...TWH
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
215 PM PDT Sun Aug 15 2021
.SYNOPSIS...Westerly winds will gradually reduce smoke across most
of the area through Monday. Temperatures will slowly return to
more seasonal levels during the first half of the coming week.
&&
.DISCUSSION...An approaching upper-level shortwave trough has
helped to shift the thickest smoke to the east today, and the HRRR
smoke model continues this trend into Monday. Bluer skies are
possible along the coast by sunset today, with an even better
chance of a blue sky for sunrise on Monday (outside of any areas
of coastal clouds and fog). Smoke is expected to linger across
Trinity County closer to the source fires, but even these areas
should see air quality improvements upwind of the fires.
The upper shortwave is expected to push east of the area by
Tuesday, with a large scale trough continuing to dig over the
western U.S. through mid-week. As a result, interior temperatures
are expected to return to near seasonal normals through Thursday.
Another interior warm-up will likely accompany building high
pressure the latter portion of next week. Winds are forecast to
shift offshore starting on Tuesday and Wednesday. Gusty north to
northeast winds will be possible on Wednesday, which would bring
smoke from all the active wildfires back toward the coast. The
combination of these gusty winds and drier air filtering in may
lead to increased fire weather concerns across portions of the
interior (see fire weather section below). In addition, coastal
temperatures may also be on the increase during this timeframe,
but the westward propagation of smoke may help negate the coastal
warm up. /SEC
&&
.AVIATION...Conditions at coastal terminals have been sporadic LIFR
to MVFR today as weak gyres slide down the coast causing waves of
fog and stratus. Expect alternating VFR to IFR CIGS and VSBYS this
afternoon. This evening as the marine layer redevelops into the
coast expect the LIFR CIGS and VSBY to return for the night. Smoke
should steadily improve over the interior today and Monday as
increased afternoon westerly winds advect it eastward...however a
brief period of MVFR haze is possible again on Monday morning at
KUKI. /MKN
&&
.MARINE...Winds will continue to increase tonight south of Cape
Mendocino, then quickly increase on Monday and Tuesday over all
zones. Northerlies are expected to top out as Gales around midday on
Tuesday over the outer waters. Have issued a SCA for PZZ470 ahead of
the possible Gale and a Gale watch for the outer water for Tuesday
into Wednesday. Steep, short-period seas will build in response to
the increasing winds. These steep seas may propagate into the inner
zones, necessitating some hazardous seas products. Stay tuned! Winds
will start to slowly weaken by Wednesday afternoon, but will remain
elevated over portions of the outer waters the back half of the work
week. Otherwise, a mid-period northwest swell will continue to
diminish as a longer-period south to southwest swell lingers. /MKN
&&
.FIRE WEATHER...Thick smoke, both at the surface and aloft, will
continue to shift east this afternoon and tonight as a shortwave
trough approaches the area. Otherwise, RH recoveries will remain
rather poor today into early next week outside of valleys and
lower slopes. Stronger diurnal westerlies in the wind channeled
gaps and valleys in the interior will develop this afternoon and
Monday as the aforementioned upper level shortwave trough moves
toward and eventually across the area. These winds may drive a
brief period of local red-flag conditions this afternoon across
the southern portion of the area. However their duration doesn`t
support a warning at this time, so will continue headlines for
276, 277, and 264. Current HRRR smoke guidance is indicating that
most areas outside of E Trinity County will be scoured of smoke by
these winds this evening through Monday.
Stronger NE-E ridge level winds and poor overnight RH recoveries
will be possible Tuesday night and Wednesday as a larger trough
digs to our east and high pressure builds over the Great Basin by
the middle of the coming week. Will headline this possibility as
well in the upcoming FWF issuance for the SE fire wx zones. /SEC
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM this evening for CAZ110-111-113>115.
NORTHWEST CALIFORNIA COASTAL WATERS...
Gale Watch from late Monday night through Wednesday morning
for PZZ470-475.
Small Craft Advisory from 5 PM Monday to 5 AM Tuesday
for PZZ470.
Small Craft Advisory from 5 PM this afternoon to 3 PM Tuesday
for PZZ455.
Small Craft Advisory until 5 AM Tuesday for PZZ475.
$$
Visit us at https://www.weather.gov/eureka
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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Glasgow MT
848 PM MDT Sun Aug 15 2021
.DISCUSSION...
...High fire danger and hot temperatures will remain a concern
into Monday for NE Montana...
845PM UPDATE:
Most things remained relatively untouched. The main interest was
Smoke, Haze, and Visibility observations that showed that pockets
of "Clearer" air exist with almost 10 miles vis. Attempted to
capture these pockets with the GLAMP/NBM as a base and then
rebuilt the weather grid`s haze/smoke qualities from there. GAH
AFTERNOON UPDATE:
Some tweaks were made to temperature, humidity and smoke grids,
coincident with the main concerns through Monday. A Heat Advisory
was deemed necessary as the hot temperatures south of the Missouri
River will be potentially hazardous in the afternoon. Air quality
will remain a concern as well, with the wildfire smoke reducing
visibility to between 3SM-5SM across much of the region. Rain is
still expected around mid-week, but confidence is not yet high as
the accumulation potential continues to fluctuate with each
forecast iteration.
Cliff
MORNING DISCUSSION:
Hot and dry conditions are expected to continue into Monday as a
western U.S. upper ridge continues to extend influence into the
Northern High Plains. Low afternoon humidity today and Monday with
little recovery tonight, combined with breezy conditions at times
will lead to high fire danger. The strongest winds are still
expected on Monday as a cold front approaches. Isolated thunder is
also possible in the west Monday evening. HRRR guidance continues
to suggest that haze and smoke may become more problematic today
in the context of both visibility and air quality.
High temperatures today and Monday will reach the mid 90s to low
100s for most places in NE Montana. In addition, temperatures may
only fall off to around 70 in southwest portions of the CWA and
near Fort Peck Lake tonight by Monday morning. The bottom line
here is that by Monday there may begin to be some cumulative
effects from the heat, even where summer in general has been
warmer than average to begin with. There is some uncertainty on
how smoke will affect temperatures today, so Monday may be the
larger impact day, especially if it becomes the third straight day
with highs in the mid 90s to low 100s. A targeted heat advisory
may be appropriate by Monday, depending on how things shape up,
but will continue to hold off for now. Lastly, breezy conditions
may rise to the level of Lake Wind Advisory criteria in and around
the Fort Peck Lake area by Monday afternoon and evening. West
winds of 15 to 25 mph with gusts to 30 to 35 mph are possible.
Again, there is still time for further consideration on these
ideas.
An upper trough pattern looks to set up for the middle of the week
with cooler and more unsettled conditions appearing more probable.
At this time, ensembles are beginning to suggest a soaking rain
for portions of NE Montana on Tuesday night into Wednesday, before
things trend back toward the hit or miss variety for the end of
the week.
&&
.AVIATION...
LAST UPDATED: 0245Z
FLIGHT CAT: MVFR-VFR
DISCUSSION: Smoke from western wildfires will continue to hamper
visibility across the region through Monday, though there will
potentially be a brief respite from MVFR visibility this evening
and overnight, before the more dense smoke is expected to move
back into the region mid-Monday. Clouds should remain minimal and
above VFR levels if any do happen to pass over an airfield.
WIND: Light and variable overnight. Then, west to northwest at
10-20 kts on Monday. Becoming light and variable again late Monday
evening.
Cliff/GAH
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until midnight MDT Monday night for
MTZ120-122-134>137.
Heat Advisory from noon to 8 PM MDT Monday for Dawson...
Garfield...McCone...Petroleum...Prairie...Richland...Wibaux.
&&
$$
weather.gov/glasgow
mid-week. More on this in the extended forecast discussion below.
.LONG TERM...Tuesday through Sunday
Issued at 233 PM MDT Sun Aug 15 2021
The next trough begins to take shape over the Pacific Northwest
Tuesday with southwest flow across the forecast area. This will
favor above normal temperatures, gusty southwest wind across the
south, and the best chance for showers over the northwest
mountains Tuesday. The trough makes slow progress to the
southeast Wednesday as it becomes cut-off from the main branch of
the northern stream jet. This slower motion has been preferred by
the ECMWF and the latest GFS is more in-line with this solution.
This will bring the trough and associated upper low to our western
doorstep late Wednesday. Showers and thunderstorms will become
widespread during the afternoon aided by a south-north oriented
jet streak across the west. This activity shifts slowly east
Wednesday evening with areas east of the Continental Divide seeing
the best chance for an extended wet period. Six-hour QPF of 0.10
to 0.25 inch advertised for most of the forecast area from
18Z/Wednesday to 06Z/Thursday. Temperatures will be below seasonal
normals Wednesday, particularly across the eastern zones.
Northerly wind behind a Tuesday night cold front may keep northern
zones 65 to 75F Wednesday. Have trended post-frontal winds upward
in the northern Bighorn Basin and Johnson County Tuesday night
and Wednesday, while also boosting pre-frontal westerly wind in
the south.
An upstream kicker arrives Thursday with some hint the trough may
become negatively tilted as it tracks through the forecast area.
Overrunning set-up with upslope flow east of the Divide and
southerly flow spreading over the top. This will keep scattered to
likely precipitation chances along and east of the Divide Thursday
and Thursday evening. Thursday temperatures remain below normal with
65 to 75F for many locations. General troughiness lingers Friday
along with the best chance for scattered showers and storms over the
northern-third of the area. Temperatures remain cool Friday. Have
boosted west-northwest winds both days across the southern tier of
zones. The upper flow becomes more zonal Saturday and Sunday
favoring showers along and west of the Divide. Temperatures rebound
5 to 8F each day.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday)
Issued at 435 PM MDT Sun Aug 15 2021
Terminals will generally be VFR, although MVFR visibility due to
wildfire smoke remains a possibility. Ongoing convection will be on
the decrease in coverage and intensity between 00Z-03Z/Monday. Main
hazard remains gusty outflow wind 35-45 kts. A mostly clear sky and
dry conditions prevail overnight and Monday with wind speeds less
than 12 kts at all terminals.
Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on smoke, icing, and turbulence forecasts.
&&
.FIRE WEATHER...
Issued AT 233 PM MDT Sun Aug 15 2021
Keeping with the RFD across southern Lincoln County for today with
low RH, above normal temperatures, and breezy winds. Winds still
look to be marginal enough to keep the RFD and not upgrade to a
warning. Tomorrow, continuing with only marginal/RFD conditions as
winds are not expected to increase enough ahead of the trough until
Tuesday. Tuesday will see the best chances for the need for a
watch/warning. Gusty winds associated with a trough and increasing
pressure gradient combined with the continuing above normal
temperatures and dry conditions, will definitely elevate the fire
weather conditions to near critical levels Tuesday. Fairly
widespread precipitation and cold front passage Tuesday night will
increase RHs and decrease temperatures for the rest of the week, so
despite gusty winds with the trough passage, fire weather conditions
do not look to be much of a concern after Tuesday evening.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Fisher
LONG TERM...CNJ
AVIATION...CNJ
FIRE WEATHER...Fisher
Area Forecast Discussion
National Weather Service San Diego CA
149 PM PDT Sun Aug 15 2021
.SYNOPSIS...
A strong ridge, centered over northern California, will team up with
a west bound trough over Mexico, to keep a brisk easterly flow aloft
over Southern California through Monday. Monsoonal moisture embedded
in that flow will bring periods of clouds and even a chance for a
stray shower or thunderstorm at times. The best chance for any heavy
rainfall will be near the mountains and over the high deserts.
Occasional clouds and increasing low-level moisture will help to
moderate daytime temperatures, except over the high deserts where
excessive heat is expected through Monday. Later this week, a trough
along the West Coast will bring a drier southwest flow aloft, and
cooler weather.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
-Forecast Highlights-
* Monsoonal flow through Wednesday, but limited thunderstorms
* Drier late this week while turning slightly cooler
An upper ridge anchored over NorCal along with weak troughing over
northwest Mexico will continue to lead to an easterly monsoonal
flow pattern across the service area. However, there are some
limiting factors for much convection -- overall subsidence from
the strong ridge and fast mid level east-northeast winds. The
wind flow will be gradually weakening through Tuesday, but by
then we start losing the best moisture as some drying starts to
move in from the north as an upper trough approaches from the
north, replacing the ridge currently in place.
Hi-res models show very limited activity. In fact, our local WRF
is a blank slate through Tuesday. HRRR shows nothing through
Monday night. However, models have struggled with the
showers/isolated tstorms that have been moving west in the fast
flow near the international border. So while showers or
thunderstorms will be few and far between over the next few days,
or may not occur at all, have kept a slight chance in the
mountains through Wednesday, except even west of the mountains
through far southern San Diego County through this evening.
Will have to keep an eye to the east as any convection forming
over Arizona or southeast California could move in on the faster
easterly flow through Tuesday morning. However, all indications
point to little if any activity moving in from the east.
Rainfall amounts will be limited as well over the next couple days
as any cells that develop will be on the move, so flash flooding
is not expected. Most locales won`t receive any rain. Places that
do are most likely to see less than a tenth of an inch with the
heaviest likely no higher than a half an inch.
One item worth mentioning is the HRRR shows smoke increasing aloft
from the north through Tuesday, so the sky will become very hazy
Monday-Tuesday and possibly Wednesday as well. The good news is
that this smoke will be mostly aloft, though near surface smoke
does increase some over the high desert, but the mountains block
this from moving further south.
Drier air will move in mid-late week under the influence of the
upper trough passing north of the region, so dry weather is
expected confidently all areas by Thursday and continuing through
the weekend. The marine layer will become slightly deeper with low
clouds at night moving into the valleys late this week.
Temperatures will cool from the hot inland conditions we are
currently seeing.
&&
.AVIATION...
152045Z...Coast/Valleys...Variable SCT-BKN clouds at/above 10000 ft
MSL will continue through Mon with mostly unrestricted vis. Patchy
stratus with bases 700-1100 ft MSL and tops to 1200 ft MSL will be
possible near the coast 06Z-16Z Mon with local vis 2-4 miles in BR
over higher coastal terrain.
Mountains/Deserts...Variable SCT-BKN clouds at/above 10000 ft MSL
will continue through Mon. There is a slight chance of TSRA over the
mountains this afternoon and again Mon afternoon with bases 9000 ft
MSL and tops to 40000 ft MSL and strong up/downdrafts this
afternoon.
&&
.MARINE...
No hazardous marine conditions are expected through Friday.
&&
.SKYWARN...
Skywarn activation is not requested.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 8 PM PDT Monday for Apple and
Lucerne Valleys.
PZ...NONE.
&&
$$
PUBLIC...Gregoria
AVIATION/MARINE...Maxwell
Area Forecast Discussion
National Weather Service Las Vegas NV
220 PM PDT Sun Aug 15 2021
.SYNOPSIS...A strong area of high pressure moving down from
northwest Nevada will lead to above normal temperatures through
Monday. Isolated afternoon thunderstorms will continue over the
mountains of southern Nevada and southeast California, with greater
storm coverage over northwest Arizona through Tuesday. Cooler
temperatures and a slow drying trend are expected to spread over the
region after Tuesday.
&&
.SHORT TERM...through Wednesday.
Satellite loops showed that convective cells initiating over the
mountains of south central Nevada and southwest Utah were moving
slowly toward the south-southwest under the clockwise flow of the
500 mb high centered over northwest Nevada. Latest runs of the HRRR
and HREF do not indicate that any storms will make much progress
into Clark County this evening, but always have to be open to the
slight possibility that it could happen in this pattern. Even though
dewpoints have been in the upper 50 to lower 60s over central Clark
County, it is apparent that moisture is quite shallow looking at
buildups over the Spring Mountains this afternoon and this is
reflected by MLCAPE values around 500 J/kg. Higher moisture content
over Mohave County was getting more surface heating today and could
be a little more primed for thunderstorms moving in from the rim
country late this afternoon and evening. The HRRR and HREF continue
to indicated the possibility of storms, or at least outflow, making
it across the area from Peach Springs to Kingman and Hualapai
Mountain. Any thunderstorms should dissipate by late evening.
The high to our northwest is forecast to be pushed over southern
Nevada Monday afternoon by a large trough digging in from the
Pacific Northwest. This should suppress convection a little more
than today with a slight warming of temps aloft and northerly flow
over northwest Arizona which will be less favorable for any storms
to move in from the rim country. The northerly flow aloft will
continue to spread smoke and haze farther southward and the latest
HRRR smoke forecast shows it will be most prevalent over Inyo,
western San Bernardino counties and south central Nevada. It looks
like it should remain fairly diffuse over Clark County southward.
Above normal temperatures will continue through Monday before the
high breaks down and pushes off to the east and no changes are
planned to the Excessive Heat Warning/Advisory in effect for areas
west and north of the Las Vegas Valley.
The incoming trough may briefly induce some low level southerly flow
Tuesday which would bring some 925-850 moisture influx up across
northwest Arizona. Chances for thunderstorms are confined primarily
over Mohave and Lincoln counties. After that, it appears it will
have a drying effect Wednesday onward with increasingly dry
southwest to westerly flow aloft spreading over the region.
Temperatures will also drop 4-8 degrees across the region from
Tuesday to Wednesday.
.LONG TERM...Thursday through Sunday.
The ensemble means indicate that we will see a break in the monsoon
pattern through the weekend and possibly beyond as dry westerly flow
behind the trough spreads and holds over the region. Chances for
thunderstorms will be confined to far northern Mohave and eastern
Lincoln County Thursday then chances will continue to diminish to
less than 10 percent going into the weekend and temperatures will
remain slightly below normal.
&&
.AVIATION...For McCarran...Light winds favoring east or southeast
directions are expected through early evening before trending more
southerly by sundown. Just FEW-SCT clouds expected around 12kft with
no thunderstorm activity expected in the Las Vegas Valley vicinity
today or Monday, though some scattered cumulus build ups are likely
over the high terrain.
For the rest of southern Nevada, northwest Arizona and southeast
California...Generally light winds favoring typical daily trends are
expected for the regional TAF sites, with thunderstorm activity
limited to northwest Arizona. Some smoke will reduce both surface
and slantwise visibility across the Sierra and southern Great Basin,
with visibility reduced to as low as 2 miles possible near KBIH
through tomorrow night.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM/LONG TERM...Adair
AVIATION...Outler
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