Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/09/21
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
513 PM MDT Wed Sep 8 2021
.AVIATION...
00Z TAF CYCLE
A few anemic thunderstorms have struggled to develop over the far
northern mountains and also the southern mountains of New Mexico, but
these short-lived cells will pose more of a gusty wind hazard rather than
any appreciable downpours. The potential for these storms will fade
after sunset. Another very low probability day for weak, brief-
lived storms is expected on Thursday, mainly over the southwestern
mountains of New Mexico. Otherwise, faint haze (from CA wildfire
smoke) will continue to wrap into much of central and eastern New
Mexico, but any visibility reductions should be minimal with VFR
conditions prevailing. Finally, hot temperatures will continue with
high density altitude readings that could create difficult ascending
conditions for some aircraft.
52
&&
.PREV DISCUSSION...224 PM MDT Wed Sep 8 2021...
.SYNOPSIS...
Hot and dry conditions will be the rule for much of the next week.
Expect record high temperatures to be broken in many locations over
the next few days. Haze will continue through Friday as smoke from
California wildfires filter into the area. A stray shower or
thunderstorm will be possible nearly each day, but the best chance
may be across northern New Mexico on Saturday. Even so, measurable
precipitation will be hard to come by.
&&
.DISCUSSION...
SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)...
Patchy low clouds in the vicinity of Tucumcari dissipated by
mid morning and now scattered cumulus are observed over the western
and northern mountain peaks with a dinky cell northwest of Las Vegas
currently showing up on radar. Expect there may be additional
isolated cells for the rest of this afternoon over the high terrain
but they should be short lived with gusty winds and very localized
rain, if any. Any activity should quickly diminish between peak
heating and sunset.
The upper high center analyzed over Utah this morning is forecast to
drift over New Mexico during the next 24 hours. Near record to
record breaking heat and lingering moisture may allow for isolated
cells to form again Thursday afternoon over the higher terrain,
similar to today. Haze from wildfire smoke will continue to
circulate through the upper high and over New Mexico but the HRRR
near surface smoke forecast is not indicative of any impacts for
tonight or Thursday. Overnight lows will be about 5-10 degrees
warmer than usual for this time of year.
LONG TERM...(FRIDAY THROUGH TUESDAY)...
Record to near record heat will continue on Friday as the upper
level high centers over NM. Smoke/haze will likely continue as well,
at least for eastern portions of the state. The weekend will remain
quite hot as the upper high elongates over the southern states. High
temperatures will be 5 to 15 degrees above normal. Models are still
spitting out a little bit of QPF Saturday and Saturday night across
the northern half of the state as a disturbance moves over the top of
the ridge. However, confidence is low this will result in measurable
precipitation given weak forcing and low dewpoints.
Models are struggling early next week regarding the timing and
placement of a trough moving over the west coast as well as a back
door front that may take aim at eastern NM on Tuesday. Regarding the
trough, ensembles show little in the way of this feature and rather
keeps the high elongated over the area. Nonetheless, these two
features will have to be watched, but for now, Monday and Tuesday
look to remain fairly dry with temperatures remaining above normal.
99/34
&&
.FIRE WEATHER...
Upper ridge over Utah today will drift to the southeast and over New
Mexico Thursday where it will remain through the weekend, if not
into early next week. Near record heat, dry and unstable conditions
will be widespread through Saturday before high temperatures start
to cool a few degrees as the upper high weakens slightly.
Fair to poor overnight humidity recoveries over north central New
Mexico tonight and Thursday night will become more widespread over
eastern and central New Mexico Friday night and over the weekend
while minimum humidities linger near or below 15 percent across
northern New Mexico. Isolated short lived showers or a storm or two
with gusty winds and little rain are possible over the northern and
western peaks through Thursday, and over the peaks near the Colorado
border on Saturday. A cold front may impact the eastern plains next
Tuesday/Wednesday but forecast models are not in agreement with that
feature. Winds through the forecast period will be generally light,
so despite the heat, dryness and instability, critical conditions
are not expected through the next 7 days.
99
&&
.AVIATION...
18Z TAF CYCLE
Upper high centered over UT and will slide sewd to north central NM
during the next 24 hrs. Isold high based convection with gusty winds
may be found over the nrn and south central mts, Gila and portions
of sern NM prior to 09/02Z. Otherwise haze from wildfire smoke may
restrict vsbys at times but generally not below VFR.
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service La Crosse WI
1036 PM CDT Wed Sep 8 2021
.SHORT TERM...(Through tonight)
Issued at 242 PM CDT Wed Sep 8 2021
The primary forecast concern for this afternoon and evening is the
introduction of showers to the area. GOES water vapor imagery shows
a well-formed shortwave trough in northern MN rotating southward
within the large-scale upper trough and cyclonic flow regime.
Radar showing a nice batch of showers in northeast MN with this
wave. Elsewhere, isolated showers are developing north of I-94.
Currently there is broken cloud coverage over areas along and
north of I-94 in NE MN and NW WI, with scattered cloud cover in SW
WI and cooler temperatures in the mid-60s to low 70s across the
area.
Upstream, colder, ice top clouds and showers can be expected to
shift into the area from north to south, mainly in WI per satellite
and the RAP 500mb vorticity track. CAMs generally show scattered
precipitation along the path of the shortwave trough and reaching
northern Taylor Cty WI by 20Z...points southward in the 21-23Z
window. Highest lapse rates are located in central and western WI
at about 6.8 degC/km and focus along the Mississippi River. These
areas will have the best chance for precipitation and some
isolated thunderstorms as clouds are deepest. Otherwise, strong to
severe storms are not expected through the afternoon and into the
evening as there is not enough instability indicated by CAM
soundings. Showers are expected to be located primarily in WI but
could inch westward into SE MN. Showers are expected to diminish
and slowly move out of the area by 02Z.
.LONG TERM...(Thursday night through Wednesday)
Issued at 242 PM CDT Wed Sep 8 2021
An upper-level ridge sits off to the west over the Rocky Mountains
as surface high pressure slides into the region on Thursday. This
would bring quiet weather conditions and relatively light winds to
the region. Mostly clear skies and a deep, light wind layer
overnight sets up a favorable environment for valley fog development
Friday morning. For Saturday, slightly warmer conditions are
anticipated with afternoon temperatures reaching into the upper 70s
to low 80s as 850 mb temperatures increase to around 20C.
The upper-level ridge is looking to break down over the weekend as a
low pressure system moves eastward through Canada. The pattern
becomes more active through early next week with several passing
shortwaves. There are periodic chances for precipitation Sunday
through the first half of the new work week. With low predictability
of the strength and exact timing of these shortwaves from a lack of
consensus between model guidance and their ensembles, decided to
stick with the blended model guidance (NBM).
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1030 PM CDT Wed Sep 8 2021
VFR conditions expected through the TAF period. The showers have
dissipated, however we will continue to see patchy mid clouds
fl050-100 through the period. Increased cumulus development is again
forecast for Thursday with a few showers possible. Due to the low
coverage, will not include in the TAF. Northwest winds generally
5 to 10kts or light and variable.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Dahl
LONG TERM...Peters
AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Boise ID
842 PM MDT Wed Sep 8 2021
.DISCUSSION...
High pressure in the Desert Southwest continues to bring Southwest
flow advecting CA and OR wildfire smoke into the region. This has
led to above normal (and some record) temperatures throughout the
region, but a cooling trend will start on Thursday. Some high
level clouds will continue to stream into the area in a line
northwest of Burns, OR and McCall, ID. A deep trough will bring a
significant shift in weather starting Thursday evening. This will
bring intermittent showers and thunderstorms to the Intermountain
West into the weekend. The Air Quality Alert is still in effect
and the Red Flag Warning will expire at 9pm. No changes to the
forecast at this time.
&&
.AVIATION...
Smoke continues to persist throughout the area, with higher
concentrations in KBNO leading to IFR conditions. Most other
regions are experiencing MVFR-VFR conditions. Some high level
clouds will continue to stream into the area in a line Northwest
of KBNO-KMYL. Intermittent showers and thunderstorms will affect
Southeast OR into western ID on Thursday evening. Surface winds:
Southwest 10-15 kts mainly over Southwest Oregon becoming light
and variable after midnight. Winds aloft at 10k ft MSL:
Southwest 10-25 kts.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Friday night...Smoke is the main
feature of current weather with extra input from the Cougar Peak
Fire in south-central Oregon. Temperatures continue above normal
with the upper ridge still in the eastern Great Basin slowly
exiting to the east-southeast. Upstream a Pacific upper trough
will move onto the northwest coast Thursday night. Ahead of the
trough moisture will increase on south-southwesterly flow aloft
through California with some input from a tropical storm near
southern Baja California. The moisture and approaching trough will
begin isolated thunderstorms in western Baker and Harney Counties
late Thursday afternoon. Showers and a chance of thunderstorms
will spread eastward to the OR/ID border overnight, with showers
beginning in the west central Idaho mountains before sunrise
Friday. HRRR shows thunderstorm wind gusts in southern Harney
County late Thursday but not nearly as strong as forecast early
this morning. Winds are forecast to decrease before reaching
southwest Idaho Thursday night. Friday morning eastern Oregon will
have widespread showers and a chance of thunderstorms, shifting
into western Idaho midday Friday. Northern mountains in Idaho may
receive up to a half inch of rain and southern areas up to a
quarter inch. High temps Friday will be 15 to 20 degrees cooler
than Thursday. The showers and thunderstorms will retreat to Idaho
north of the Snake Basin Friday evening, and to Valley County/ID
by morning. Air quality advisories remain in effect through
Thursday afternoon in southeast Oregon, and through 1 PM MDT
Friday in western Idaho. The showers and westerly winds aloft with
the upper trough should decrease the smoke on Friday.
LONG TERM...Saturday through Wednesday...Weak troughing will
remain over the region through the extended period with west to
northwest flow aloft. Weak, fast moving, shortwaves will pass
nearby in this flow, but timing varies quite a bit among the
different model solutions. Our northern mountain zones look to
have the best chance for showers through this period. Temperatures
in this nearly zonal flow situation will stay near seasonable
normals through the middle of the week. Smoke is also likely to
remain south of the region with this flow pattern provided no new
fires start later this week.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning until 9 PM MDT this evening IDZ402-403.
OR...None.
&&
$$
www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise
DISCUSSION...SA
AVIATION.....SA
PREV SHORT TERM...LC
PREV LONG TERM....JDS
Area Forecast Discussion
National Weather Service Denver/Boulder CO
900 PM MDT Wed Sep 8 2021
.UPDATE...
Issued at 859 PM MDT Wed Sep 8 2021
Another quiet and dry night for the forecast area. Light winds and
a very dry airmass will spell good radiational cooling in most
locations. Last of the cirrus is passing off to our southeast so
clear, but smoky, skies will prevail. The smoke will linger over
our forecast area through all of Thursday.
High temperatures will be warming with further warm advection,
weak lee troughing, and sunshine. Record high for Denver is 94
last set in 1994, and we should break that by a degree or two.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 143 PM MDT Wed Sep 8 2021
Very dry air continues to spread across the region with the center
of a strong ridge slowly tracking eastward. This feature will
continue to push over the state from the Great Basin reducing
upper air flow and dropping humidity values through the column.
There will be a weak surge of upper level clouds that will spill
over the ridge over northeast Colorado into the evening. As the
ridge moves east this will help to scatter those out leaving
mostly sunny conditions for Thursday. A surface low early Thursday
will form bringing southwest surface winds pushing daytime highs
back into the mid- 90s across the plains.
Smoke impacts will continue with the low level flow combined with
the transport winds that will mix down during the day. The latest
HRRR guidance reflects this but still seems to be underdone.
Surface winds will switch around to the ENE that could help the
plains to improve slightly into the evening.
.LONG TERM...(Thursday night through Wednesday)
Issued at 143 PM MDT Wed Sep 8 2021
Record heat is expected on Friday and perhaps into Saturday as the
robust upper level ridge continues to sit nearby. NAEFS 500mb Z
and 700mb T climatological percentiles are near or above the 99th
percentile across the state, and therefore it`s no real surprise
that the forecast high for Denver is well above the current daily
record. Our current forecast high of 98F would be tied for the
third warmest temperature on record in September (101F in 2020,
100F in 2019) and would shatter the current daily record of 93F
(2018).
The ridge will sink southward and flatten on Saturday with a weak
shortwave approaching from the northwest. Temperatures will likely
be above average, but there should be at least modest relief from
the heat. PWATs increase to near/above normal values,
particularly over the northwest part of the forecast area, and
there should be better convective coverage in the afternoon.
Despite the slightly cooler temperatures, forecast highs are still
near record values for Saturday, with another day in the low 90s
expected.
Zonal flow establishes itself across most of the region by Sunday,
with slightly cooler temperatures...in the upper 80s... for the
plains. Guidance suggests there should be just enough
moisture/instability for continued afternoon showers/storms,
especially for the higher elevations, but most of this precip
should be light.
Model guidance diverges Monday and beyond, though the general
pattern looks supportive of a few weak shortwaves tracking along
the periphery of the ridge. If the ridge stays fairly weak, that
could mean a few weak cold fronts and temperatures in the upper
70s to low 80s. If the ridge is stronger, above normal
temperatures would likely continue for the foreseeable future.
We`ll hope for more clarity (and if this forecaster gets to
choose, a cooler pattern) soon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 859 PM MDT Wed Sep 8 2021
Smoke and slant range visibility may force ILS landing conditions
at KDEN through Thursday. Surface visibility may dip to around 6SM
at times - mainly during the daylight hours. Otherwise, once winds
turn back to normal drainage winds tonight toward 05Z-07Z, fairly
normal diurnal wind patterns will prevail at 10 knots or less.
&&
.FIRE WEATHER...
Issued at 143 PM MDT Wed Sep 8 2021
Elevated fire weather conditions for Thursday with RH values
dropping into the teens and single digits across the region
combined with unseasonably warm temperatures. Elevated fire danger
will continue on Friday with RH below 10% across the majority of
the forecast area. Winds are expected to remain fairly weak
underneath the ridge, but near Red Flag criteria will still be
possible over the windier spots of Grand and Jackson counties.
Moisture increases by Saturday with chances for afternoon showers
and storms. Humidity values should generally remain above 15%
through next week, with a few afternoon showers/storms possible
each day.
&&
.HYDROLOGY...
Issued at 143 PM MDT Wed Sep 8 2021
No flash flooding concerns through Friday with very hot and dry
conditions likely. Chances for rain return to the high country
this weekend, but precipitation amounts look fairly light and the
overall threat should remain low.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Barjenbruch
SHORT TERM...Bowen
LONG TERM...Hiris
AVIATION...Barjenbruch
FIRE WEATHER...Bowen/Hiris
HYDROLOGY...Bowen/Hiris
Area Forecast Discussion
National Weather Service Quad Cities IA IL
611 PM CDT Wed Sep 8 2021
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 1223 PM CDT Wed Sep 8 2021
A beautiful late summer day was unfolding across all of eastern
Iowa, northwest Illinois and far northeast Missouri with plentiful
sunshine and a cool northwest breeze. Temperatures as of noon ranged
from the low to upper 70s, with comfortable dewpoints ranging from
the mid 40s to upper 50s. All of this was brought to us by northwest
flow courtesy of high pressure in the western Dakotas, and a surface
low in northern Ontario.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 1223 PM CDT Wed Sep 8 2021
[Key Messages]
*Beautiful weather over the next 24 hours with temperatures around
normal
*Breezy northwest winds this afternoon will subside this evening
[Discussion]
The few things to note for the rest of today are clouds and winds.
Latest satellite imagery showed diurnal CU was developing from
northern Illinois into central Wisconsin and and southeast
Minnesota, which has been fairly well represented by model CU rule
guidance and forecast soundings where deep mixing was occurring.
Surface winds were also gusty in these areas courtesy of the mixing,
which was bringing winds of 20-30 knots down to the surface from
around the 850-700 hPa layer. Expect this to continue through this
evening before boundary layer decoupling leads to clearing skies and
subsiding winds. Some of the more aggressive CAMs including the HRRR
and NAMnest attempt to develop rain showers in the CU field from
western Wisconsin to northeast Iowa, but this is likely overdone
given the amount of dry air to overcome in the low-levels.
Expected a persistence forecast through tomorrow as the high
pressure over the Dakotas continued building southeast into the
Midwest. Overnight lows will drop into the low to mid 50s, with PM
highs Thursday climbing into the low to upper 70s. These values are
near normal for early September. Will note that some upper 40s will
be possible in our northern CWA Iowa counties tonight where there
is a higher probability of clear skies and near calm winds.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 146 PM CDT Wed Sep 8 2021
[Key Messages]
*Dry and pleasant through the remainder of the work week
*Increasing temperatures and chances of precipitation return this
weekend into mid next week
[Discussion]
Thursday Night through Friday...
Aforementioned surface high pressure will continue to build
southeast, and will find itself situated over the Ohio River Valley
Friday. Southerly flow on the back side of the high will warm
daytime temperatures slightly, though conditions will remain quite
pleasant with dewpoints remaining below 60 degrees. Expect PM highs
Friday in the upper 70s to low 80s.
Saturday on...
Pressure gradient will begin to tighten on the back side of the
surface high as a surface low begins to develop ahead of a shortwave
and CVA over the eastern Rockies. This tightening pressure gradient
will increase return flow and quickly usher in a warmer air mass and
increasing moisture into the area beginning Saturday, with
temperatures expected to soar back above normal once again. NBM
currently advertises afternoon highs Saturday and Sunday returning
back into the mid to upper 80s, with values near 90 or higher even
possible across the far south.
A warm front is progged to develop across the Midwest Sunday, with
the surface low expected to track across it as it remains ahead of
the shortwave. Guidance remains mixed on the warm front placement
and the subsequent low track, which will be key to our precipitation
chances and how warm we get early next week. Ensembles and
deterministic guidance remain in agreement of some QPF across the
CWA Monday through Wednesday, so have maintained the chances left
over from the previous forecast package. Beyond Wednesday, guidance
splits on potential solutions with the GFS bringing a cold front
through the area Wednesday night and the ECMWF keeping southerly
flow in place through Friday. Expect changes to this forecast going
forward.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 610 PM CDT Wed Sep 8 2021
Beautiful VFR weather with consistently northwest winds 5 to 12
kts will continue through Thursday evening. Visibility will be
unlimited (P6SM).
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Speck
SHORT TERM...Speck
LONG TERM...Speck
AVIATION...Ervin
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
652 PM CDT Wed Sep 8 2021
.UPDATE...
Issued at 647 PM CDT Wed Sep 8 2021
Updated to include 00z aviation discussion below.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 247 PM CDT Wed Sep 8 2021
Scattered showers and isolated thunder is currently evident on radar
and satellite imagery across northeast Minnesota and west central
Wisconsin, with some activity getting into central and east central
Minnesota. This should be around into early evening, when the
boundary layer will start to cool and we`ll begin to see less forcing
from the shortwave evident on water vapor imagery (and RAP analyses)
over northeast Minnesota at the current time. The diurnal CU and TCU
will move out and/or dissipate during the evening, leaving mostly
clear skies overnight into Thursday night as high pressure currently
centered over the Plains shifts east across the area. There will be a
bit more cloud cover again across the east on Thursday afternoon due
to diurnal CU, but any SHRA/TSRA should stay east of our area.
.LONG TERM...(Friday through Wednesday)
Issued at 247 PM CDT Wed Sep 8 2021
Northwest upper flow at the start of the period will give way to
zonal flow over the weekend, which will remain in place into early
next week, with a somewhat amplified upper trough proggred to move
through the mean flow around Tuesday. The model guidance is in good
agreement on the overall evolution of things, but understandably has
some spread when it comes to timing and amplitude of individual
features. As always, this leads to more uncertainty as we get further
into the future, with chance PoPs needed for much of the area from
Monday through Tuesday. Prior to then, things look like they should
stay dry for most of the area over the weekend. A frontal boundary
will drop through Saturday afternoon and evening, but will have
minimal moisture with which to work, so expect it to pass through
dry. What`s left of that boundary will start to moisten to our south
on Sunday, so there`s a slight chance for precipitation over the far
south, although guidance has been trending toward keeping that south
of our area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 647 PM CDT Wed Sep 8 2021
Showers have just about exited all TAF sites at initialization time
so, aside from a small potential at KEAU over the next couple hours,
have kept the TAFs dry through this duration. Mid- and high-level
FEW/SCT clouds will continue to drift across the area within
downslope flow aloft, with coverage lessening overnight but then
increasing a bit after daybreak tomorrow due to atmospheric mixing.
Fair wx cumulus clouds in the mid-levels and streaming cirrus aloft.
Breezy/gusty NW winds this evening will diminish overnight and back
to westerly tomorrow, picking to near 10 kts.
KMSP...No additional concerns.
/OUTLOOK FOR KMSP/
FRI...VFR. Winds S 10-15 kts.
SAT...VFR. Winds W becoming N 10-15 kts.
SUN...VFR. Winds N becoming NE 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
UPDATE...JPC
SHORT TERM...
LONG TERM...
AVIATION...JPC
Area Forecast Discussion
National Weather Service Pendleton OR
903 PM PDT Wed Sep 8 2021
.UPDATE...Due to reduced temperatures across the Blues for the day
from precipitation activity, pulled overnight lows down a couple
of degrees. That being said, shouldn`t be significantly lower as
cloud cover is expected to remain overnight to help trap warmth.
Trough moves in tomorrow, making Thursday our last warm day
before cooler fall-like weather begins to overspread the region.
This trough also brings a chance of precipitation for a good
portion of the region, with very heavy rainfall possible for the
Blues into Wallowas. A marginal risk of excessive rainfall is
possible into Wallowa county into Friday. Highs on Friday then are
expected into the 70`s for the most part, with lower temperatures
for the higher elevations. Goatley/87
&&
AVIATION...06z TAFs...Smoke is starting to clear out across the
region for the evening, though some lingering haze may remain
across the region, particularly for areas like RDM. Light winds
overnight becoming breezy again tomorrow as a shortwave moves
through, with TSRA moving across RDM/BDN and across the Blues by
the end of the TAF period. Goatley/87
.PREV DISCUSSION... /issued 433 PM PDT Wed Sep 8 2021/
SHORT TERM...Tonight through Friday night...Several weather
concerns are anticipated during the short term period. The weather
pattern has been dry and stable for several days with smoke from
multiple wildfires contributing to poor air quality, particularly in
central Oregon and the Yakima Valley where air quality
alerts/advisories are in effect through Thursday. This morning`s
shortwave trough that pushed quickly across northern WA had little
effect for the forecast area except to tighten the cross-Cascade
gradient where breezy winds are occurring in the Kittitas Valley,
the Simcoe Highlands, the eastern Columbia River Gorge, and the
Lower Columbia Basin. The RHs are in the 20s--not critically low
for any fire weather highlights.
A much stronger trough is showing definite signs of cyclogenesis on
the water vapor loops with a surface low about 400 miles west of
Astoria. This low will move northeast towards Vancouver Island
tonight with an elongated trough off the coast Thursday. An
increasing southwest flow aloft will tap in Pacific and monsoonal
moisture and bring isolated thunderstorms to central and northeast
Oregon late Thursday afternoon. Showers and thunderstorm will
increase in coverage Thursday night and Friday as the upper trough
gradually traverses across WA/OR. Fire weather watches have been
issued (for more details, refer to the Fire Weather Discussion).
Based on inverted-V forecast soundings and the HRRR 10-m wind gust
potential of 35-40kts over eastern Oregon, I included gusty winds
possible with thunderstorms Thursday night. WPC has Wallowa County
included in their Excessive Rainfall Outlook for Friday. The ECMWF
Extreme Forecast Index (EFI) places a large portion of eastern Oregon
in a potential for very high QPF, and the EFI has proven well in the
past in highlighting extreme events. On the other hand, the storm
motions look fast enough that slow moving storms are not likely.
Main concerns will be heavy rain over burn scars from this season`s
wildfires--Elbow Creek, Rock Creek, Black Butte, and Joseph Canyon
to name a few.
Thursday`s winds will be breezy in some areas, mainly in the
southern half of eastern Oregon. Friday will be breezy in the
lower elevations, but significantly cooler. Wister
LONG TERM...Saturday through Wednesday...Period looks relatively
benign as a zonal pattern sets up over the weekend after Friday`s
system passes eastward. Ensembles in pretty good agreement on this
through at least Monday, before solutions begin to diverge. Some
members depict weak troughing heading into Tuesday, while others
keep ridging in place. Deterministic models reflect this as well,
with the GFS remaining relatively zonal, even depicting some ridging
by the tail end of the period, while the ECMWF leans more towards a
trough passing through Monday into Tuesday. Given model
discrepancies, will stick with NBM for now, which keeps us dry
through early next week, with a slight chance of PoPs in the upper
mountain zones. Ensembles seem somewhat consistent on another SW
flow pattern setting up by the end of next week, which is likely
where the NBM is pulling this moisture from.
Otherwise, weather looks to be quiet for most of the long term.
Temps will be seasonal, hovering around the 70s for much of the
forecast area. 74
FIRE WEATHER...Fire Weather Watches are in effect from late
Thursday afternoon through Friday afternoon for thunderstorms
producing abundant lightning across central and northeast Oregon.
The Blue Mountains north of Ukiah are not under the watch, as most
of the lightning Thursday night will be to the south and east.
Although I am not expecting large wildfire potential, the concerns
are mainly new fire starts as well as outflow winds that could be
problematic for new fires. Some storms Thursday night and Friday
will bring moderate to heavy rain...0.5 inch for some
storms...possibly more. As previously stated, previously burned
areas from this season`s wildfires will need to be closely monitored
for heavy downpours and debris flows. The concerns are mainly
central and northeast Oregon, but Green Ridge in southeast
Washington should not be ruled out as well. Wister
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 57 86 60 72 / 0 10 10 50
ALW 60 89 61 75 / 0 0 10 60
PSC 60 90 64 77 / 0 0 0 40
YKM 54 88 57 77 / 0 0 0 10
HRI 58 90 62 77 / 0 0 10 40
ELN 55 85 57 75 / 0 0 0 10
RDM 50 85 54 72 / 0 0 30 50
LGD 56 89 58 72 / 0 10 30 80
GCD 57 95 58 75 / 0 20 30 80
DLS 62 88 64 78 / 0 0 0 20
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from Thursday afternoon through Friday
afternoon for ORZ611-640-642-644-645.
WA...None.
&&
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 57 86 60 72 / 0 10 10 50
ALW 60 89 61 75 / 0 0 10 60
PSC 60 90 64 77 / 0 0 0 40
YKM 54 88 57 77 / 0 0 0 10
HRI 58 90 62 77 / 0 0 10 40
ELN 55 85 57 75 / 0 0 0 10
RDM 50 85 54 72 / 0 0 30 50
LGD 54 89 58 72 / 0 10 30 80
GCD 55 95 58 75 / 0 20 30 80
DLS 62 88 64 78 / 0 0 0 20
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from Thursday afternoon through Friday
afternoon for ORZ611-640-642-644-645.
WA...None.
&&
$$
SHORT TERM...87
LONG TERM....74
AVIATION...87
Area Forecast Discussion
National Weather Service Pocatello ID
233 PM MDT Wed Sep 8 2021
.SHORT TERM...Today through Saturday. High pressure ridging breaks
down and moves east setting up warm, southwest flow today as a
trough moves over northern Idaho. Expect breezy to moderate winds
for our northern areas with record to near record temperatures
for most of our area. Thursday the flow continues to be breezy,
especially for our western and northern areas, out ahead of a
system moving into the area. By Friday, an upper level low over
OR/WA will bring scattered showers and thunderstorms across the
area by Friday afternoon into the early evening. Saturday expect
breezy, dry, cooler northwest flow behind an exiting system.
However, some models are showing some lingering showers especially
over the Island Park area. Expect well above normal temperatures
today, record to near record, before becoming below normal by
Saturday.
TW
.LONG TERM...Sunday through next Wednesday.
Expect dry conditions through the period with brief periods of
breezy to moderate winds. Sunday a dry, breezy trough moves over
northern ID and Southern Canada elevating the winds over our
northern areas, especially the Central mountains. Models are still
indicating another dry, breezy trough on Tuesday, again impacting
mainly the Central mountains. Fire weather highlights may be
needed depending on relative humidity recovery. Relative humidity
will likely be below critical values, especially by Tuesday
afternoon. Models then show weak high pressure on Wednesday.
Expect 70 to 80s with cooler mountain temperatures through the
period.
TW
&&
.AVIATION...Expect VFR conditions through Thursday but a chance
of some limited visibility restrictions due to smoke down to 4 or
5 miles mainly at IDA and SUN after sunset but for now will keep
VFR. Expect clear skies with only the limited smoke visibility
restrictions for impacts. Expect more widespread showers and
thunderstorms Friday as a cold front moves through Idaho.
GK
&&
.FIRE WEATHER...Main impacts through Thursday will be gusty winds
mainly in zones 475 and 476. Have red flag warning out through 9
pm tonight for winds and low humidity and have issued for those
zones on Thursday for the gusty winds and low humidity again. Left
422 out as humidity may be slightly elevated but will look at it
again tonight. Winds won`t be as strong to the south and east
today or Thursday. Will see widespread Haines index of 6 through
Thursday as well. Main issue Friday will be impacts from upper
level trof and associated cold front moving through Idaho. Will
likely have widespread shower and thunderstorm activity with this
system and may need red flag warnings for thunderstorm coverage on
Friday as well. Will see a significant cool down of temperatures
Friday and Saturday with minimum humidity significantly higher as
well.
GK
&&
.AIR STAGNATION...Poor air quality conditions are expected through
Friday, at least, across Eastern Idaho due to wildfire smoke from
local and regional fires. There is an Air Quality Alert in effect
for the majority of the forecast area through Thursday from the
Idaho Department of Environmental Quality. The air quality has
been determined by the IDEQ to be unhealthy to sensitive groups,
and will remain in effect until air quality has significantly
improved. The HRRR smoke model brings smoke into the area through
Friday. Precipitation Friday and northwest flow aloft by late
Saturday will help bring better air quality conditions into the
area.
TW
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for IDZ475-476.
Red Flag Warning from noon to 9 PM MDT Thursday for IDZ475-476.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
405 PM MST Wed Sep 8 2021
.UPDATE...
Updated Aviation
&&
.SYNOPSIS...
Strong high pressure aloft will persist across the Southwestern U.S.
through the rest of this week providing above normal temperatures
for much of the region. Generally dry conditions will also prevail
despite somewhat higher humidity levels. However, slight chances for
storms will be possible across far southern Arizona today and across
southeast California and the Arizona higher terrain Thursday into
Friday. Daily high temperatures through the weekend will mostly
range from 105 to 108 degrees across the Arizona lower deserts to a
couple of degrees warmer across southeast California and southwest
Arizona.
&&
.DISCUSSION...
The anomalously strong upper level ridge covering most of the
Western U.S. is very slowly drifting eastward and should eventually
be centered over the Four Corners area early Thursday before
stalling out over New Mexico Friday through the upcoming weekend.
Unseasonably warm temperatures across our region will be the main
impact through at least the upcoming weekend, but we may also have
some isolated thunderstorms to contend with around the outer fringes
of the high.
This morning saw a very strong gulf surge across SW AZ/SE CA as
outflows from a very strong MCV that decayed over northern Sonora
pushed northwestward up the Gulf of California into the region. Yuma
airport recorded a peak gust of 43 mph and 3SM visibility in blowing
dust, with dewpoints rising into the mid-70`s across parts of SE
CA/SW AZ. Although low-level moisture levels have been improved by
this gulf surge, convective activity is non-existent across the
region this hours as strong subsidence aloft has produced a couple
of mid-level warm layers in the column. Although convective activity
is not expected this afternoon/evening at most locations, a PV
anomaly tracking westward across extreme southern AZ around the base
of the upper-level high center is expected to trigger at least a few
T-storms across central/western Pima County late this
afternoon/early evening. Right now SPC does have a portion of south-
central AZ in a "marginal" area for severe wind gusts, but they do
keep this area. Latest HRRR and SPC HREF guidance does some storm
development across Pima County, but with only some isolated storms
making their way into SE Yuma/extreme SW Maricopa Counties.A greater
threat is strong outflow winds/blowing dust impacting motorists on I-
8 between Dateland and Casa Grande, with lesser chances for dust
making its way into the Yuma area.
The focus of convective activity is expected to shift westward into
SW CA as the upper-level high center repositions itself over
northern NM, with the flow aloft becoming more southerly. The main
mid-level moisture plume is expected to shift westward, with
additional moisture being sheared northward from Tropical Storm Olaf
into CA. Latest high-res CAMs are indicating T-storm development
over the higher terrain of northern Baja CA/southern CA during the
midday/early afternoon hours on Thursday. Some of this activity
appears it will attempt to push its way into extreme SW Imperial
County and into Joshua Tree NP late tomorrow afternoon/early
evening. The main threats will be strong outflow winds/brief heavy
rains, as the forecast soundings across that region showing a lot of
DCAPE (1500-2000 J/kg), but fairly limited moisture (PWATS in the
1.00-1.20 inch range).
Perhaps the bigger story the next couple of days is the very hot
temps. 500mb heights in the 592-595dm range are expected to allow
temps into the 106-111 degree range today and Thursday. The hottest
temps are expected over parts of Riverside County today, then shift
eastward into Maricopa County on Thursday. The latest NBM now shows
a 30% probability of Phoenix reaching its daily record high of 110
degrees and a 67% probability of reaching 108 or higher on Thursday.
Thus the Excessive Heat Watch that was in effect for the Phoenix
metro area has been upgraded to an Excessive Heat Warning.
As the ridge re-centers itself over New Mexico Friday into the
weekend, temperatures should lower a couple degrees starting Friday,
but remain several degrees above normal. A return to High HeatRisk
potential is looking more likely for Sunday into Monday as further
drying of the boundary layer and a slight westward shift of the
upper level ridge will likely allow daytime highs to rise back to
around 110 degrees. The latest NBM output has tightened the spread
in temperature guidance for Sunday and Monday, with widespread
readings near 110 degrees looking very likely on Sunday with
slightly less likelihood on Monday. Either way, the unseasonably
warm conditions are likely to prevail through at least early next
week with little if any chance of rain.
&&
.AVIATION...Updated at 2305Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Skies will remain mostly clear through Thursday evening with
thunderstorm activity well outside any influence to the Phoenix
terminals. While a very light SW wind will be most common this
evening, highly variable directions are likely before settling on an
E/SE heading late evening and overnight. Winds will struggle to turn
to S/SW Thursday afternoon, and in many cases may only become light
and variable versus making a distinct shift.
Southeast California/Southwest Arizona including KIPL and KBLH:
Winds will generally retain a southerly component through Thursday
evening under mostly clear skies. Thunderstorms are not expected to
directly impact either terminals, however there is about a 10-20%
chance an outflow boundary could enhance/reinforce SE winds
overnight. There may be periods of nearly calm or variable winds
through the period.
&&
.FIRE WEATHER...
Friday through Tuesday:
Strong high pressure will dominate over the Southwestern U.S.
through the weekend and likely into early next week providing
generally dry conditions and above normal temperatures. Chances for
showers and thunderstorms will be very limited through the period,
especially over the Arizona lower deserts where chances will be less
than 5%. High temperatures are likely to run a few degrees above
normal throughout the period with some lower desert areas
potentially approaching 110 degrees. Min RH levels will range from
15-25% through Saturday with readings dropping to 10-20% starting
Sunday, while max RHs generally range from 35-55% (locally higher).
Winds will overall remain light through the period while following
typical diurnal patterns.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning from Thursday morning through Thursday
evening for AZZ537-540>544-546-548>551.
CA...Excessive Heat Warning until 8 PM PDT Thursday for CAZ561-570.
&&
$$
DISCUSSION...Percha/Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman
Area Forecast Discussion
National Weather Service Pueblo CO
316 PM MDT Wed Sep 8 2021
.SHORT TERM...(This evening through Thursday)
Issued at 314 PM MDT Wed Sep 8 2021
...Hot With Lots of Smoke and Record High Temperatures Tomorrow...
...Sensitive Populations Are Encouraged To STAY INSIDE TOMORROW If
At All Possible...
Currently...
Another warm and sunny day across the region at 2 pm. Temps were in
the 80s across all of the plains and around 80F in the valleys. Hazy
skies were noted region-wide per web-cams and surface obs.
Rest of Today into Tonight...
With the large 500 mb closed high building over us, very dry air
will be moving over the region. This is clearly indicated by the
forecasted humidity and PWAT charts over the greater southeast
Colorado region. With sinking air in the midlevels, temperatures
tonight across all of the region are going to be rather (relatively)
uniform with 50s in the plains, 40s in the valleys and rather warm
mins in the 30s and 40s mtns.
Smoke will be with us through tonight, but it will decrease overall
somewhat this evening before pushing back towards sunrise.
Tomorrow...
It is going to be hot with quite a bit of smoke. The most densest
low level smoke is forecast by the HRRR near Surface Smoke product
to be over the greater I-25 corridor over southeast Colorado
tomorrow, with values of 30-40 ug/M^3. Record high temps are
forecast to be broken tomorrow by 2 to 5 degrees as the San Luis
Valley will be in the upper 80, mid 90s for Colorado Springs and
temps approaching/reaching 100F in Pueblo. Alamosa`s ALL TIME
September record high is 89, and we are forecast to reach that value
tomorrow.
For more Climate information, please go to:
www.weather.gov/wrh/climate?wfo=pub
and then click on the LOCAL DATA/GRAPHS tab for climate information
(including all record temps) for Colorado Springs, Alamosa and
Pueblo.
Due to the combination of the heat and smoke in the air, it is
recommend to stay inside tomorrow as the air is likely not going to
be all that healthy across the region. Please monitor air quality
forecast by the Colorado Department of Health and Environment for
more information.
.LONG TERM...(Thursday night through Wednesday)
Issued at 314 PM MDT Wed Sep 8 2021
Friday... Diving into the long term period, conditions look to be
hot and dry early on. A large upper level ridge and high pressure
system will be sitting right on the Colorado and New Mexico border.
This high pressure system will bring an area of synoptically sinking
air over the region which will inhibit any chances of precipitation.
The system will also continue to advect modest low to mid level
moisture into the region, which will also help to limit any type of
precipitation development. There is a chance of an isolated rain
shower/thunderstorm over the western mountains during the afternoon
given orographic forcing from southwesterly winds and a slow
moisture increase over that area. The most impactful weather from
this high pressure system will be the increase in temperatures in
response to the strong system being directly over the area. Daily
high temperature record values will likely be broken Friday
afternoon, with some places possibly setting an all time record high
for the whole month of September.
Saturday... Saturday will bring the first solid chances of
precipitation and a slight cool off to southern Colorado. An upper
level short wave disturbance will pass to the north of the area
throughout the day. This small wave will bring increased dynamics to
the area, but the more focused forcing of this system will stay to
the north thanks to the strong ridge still to south of Colorado.
This disturbance will shift winds to become more westerly aloft and
advect in a modest increase in low to mid level moisture into the
region. Given the slight uptick in moisture, orographic lifting from
westerly winds into the mountains, and the modest increase in upper
level forcing, precipitation is expected to develop over the
mountains. The precipitation will start over parts of the
Continental Divide late in the day, and push eastward, following the
upper level forcing east. At the surface, a weak cold front is
expected to drop southward over the region as well. The cold front
won`t drop temperatures drastically, but will help to cool the area
down enough so that record daily highs are not being broken; the
area will still be above average though in regard to temperatures.
Sunday - Wednesday... The GEFS and EPS ensembles continue to agree
with the overall evolution of the atmospheric flow heading into next
week. Sunday through Monday, the ridge sitting over the region
begins to flatten out for a short period. This flattening will help
to keep weather conditions relatively quiet for the Pueblo CWA. The
position of the upper level high pressure during this period though
would continue to allow for a stream of smoke to be advected toward
Colorado, and more hazy skies would be possible. On Tuesday, a
trough begins to dig southward over parts of the central plains of
the US. This will help to usher in another cold front over the area.
With passage of the cold front, surface winds will become easterly
and an upslope regime would be expected. This would allow for
precipitation to develop along the eastern mountains during the late
afternoon and evening. On Wednesday, the ridge begins building back
over the western half of the US. This will start to push in drier
air into the area and precipitation chances will decrease in
response to that.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 314 PM MDT Wed Sep 8 2021
Hazy/smoky conditions are likely during this forecast time period at
all 3 taf sites, KPUB, KALS and KCOS. MVFR conditions will be
possible at times due to the haze/smoke. The lower level smoke is
expected to be most dense tomorrow afternoon per HRRR smoke forecast
product. Surface winds will generally be light and diurnally
driven.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HODANISH
LONG TERM...SIMCOE
AVIATION...HODANISH