Red Flag Warning 9, NWS Pocatello, ID

590 
WWUS85 KPIH 290845
RFWPIH

URGENT - FIRE WEATHER MESSAGE
National Weather Service Pocatello ID
245 AM MDT Tue Aug 29 2023

IDZ425-292200-
/O.CON.KPIH.FW.W.0009.230829T2100Z-230830T0300Z/
Middle Snake River Valley/Twin Falls BLM north of the Snake River-
245 AM MDT Tue Aug 29 2023

...RED FLAG WARNING REMAINS IN EFFECT FROM 3 PM THIS AFTERNOON TO
9 PM MDT THIS EVENING FOR GUSTY WINDS AND LOW RELATIVE HUMIDITY
FOR FIRE WEATHER ZONE 425...

* AFFECTED AREA...Fire Weather Zone 425 Middle Snake River 
  Valley/Twin Falls BLM north of the Snake River.

* WINDS...Southwest 20 to 30 mph with gusts up to 45 mph shifting
  to the west between 5 PM And 8 PM.

* RELATIVE HUMIDITY...As low as 12 percent.

* IMPACTS...Hot, dry, and breezy conditions will support rapid 
  wildfire spread and long range spotting of embers.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now, or will shortly based on any one or
more of these criteria for southeast Idaho:

- Relative humidity at or below 15 percent AND wind gusts of at
least 25 MPH in the mountains or 30 MPH in the Snake Plain.

- Thunderstorm coverage of 25 percent or greater, without
specific rainfall criteria.

- Other high impact events deemed critical by the National
Weather Service and area fire management agencies.

&&

$$

289 
WWUS85 KPIH 291526
RFWPIH

URGENT - FIRE WEATHER MESSAGE
National Weather Service Pocatello ID
926 AM MDT Tue Aug 29 2023

IDZ410-427-300300-
/O.EXA.KPIH.FW.W.0009.230829T2100Z-230830T0300Z/
Upper Snake River Valley/Idaho Falls BLM-
Goose Creek and Raft River Valley/Southern Sawtooth NF/Twin Falls
BLM south of the Snake River-
926 AM MDT Tue Aug 29 2023

...RED FLAG WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO 9 PM
THIS EVENING FOR GUSTY WINDS AND LOW RELATIVE HUMIDITY FOR FIRE 
WEATHER ZONES 410 AND 427...

The National Weather Service in Pocatello has issued a Red Flag
Warning for gusty winds and low relative humidity, which is in
effect from 3 PM this afternoon to 9 PM this evening.

* AFFECTED AREA...Fire Weather Zone 410 covering the Upper Snake
  River Valley/Idaho Falls BLM, and Fire Weather Zone 427 
  covering Goose Creek and Raft River Valley/Southern Sawtooth 
  NF/Twin Falls BLM south of the Snake River.

* WINDS...South 20 to 30 MPH with gusts of 35 to 45 MPH, shifting
  into the west-southwest between 6 PM and 8 PM at similar speeds
  as a cold front pushes through. Gusty winds will linger past 9 
  PM, but relative humidity values will moisten and no longer be 
  critical.

* RELATIVE HUMIDITY...12 to 16 percent.

* IMPACTS...Hot, dry, and breezy conditions will support rapid 
  wildfire spread and long range spotting of embers.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now, or will shortly based on any one or more
of these criteria for southeast Idaho:

- Relative humidity at or below 15 percent AND wind gusts of at
  least 25 MPH in the mountains or 30 MPH in the Snake Plain.

- Thunderstorm coverage of 25 percent or greater, without 
  specific rainfall criteria.

- Other high impact events deemed critical by the National 
  Weather Service and area fire management agencies.

&&

$$

IDZ425-300300-
/O.CON.KPIH.FW.W.0009.230829T2100Z-230830T0300Z/
Middle Snake River Valley/Twin Falls BLM north of the Snake River-
926 AM MDT Tue Aug 29 2023

...RED FLAG WARNING REMAINS IN EFFECT FROM 3 PM THIS AFTERNOON TO
9 PM THIS EVENING FOR GUSTY WINDS AND LOW RELATIVE HUMIDITY FOR 
FIRE WEATHER ZONE 425...

* AFFECTED AREA...Fire Weather Zone 425 covering the Middle Snake
  River Valley/Twin Falls BLM north of the Snake River.

* WINDS...South 20 to 30 MPH with gusts of 35 to 45 MPH, shifting
  into the west between 5 PM and 7 PM at similar speeds as a cold
  front pushes through. Gusty winds will linger past 9 PM, but 
  relative humidity values will moisten and no longer be critical.

* RELATIVE HUMIDITY...10 to 15 percent.

* IMPACTS...Hot, dry, and breezy conditions will support rapid 
  wildfire spread and long range spotting of embers.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now, or will shortly based on any one or more
of these criteria for southeast Idaho:

- Relative humidity at or below 15 percent AND wind gusts of at
  least 25 MPH in the mountains or 30 MPH in the Snake Plain.

- Thunderstorm coverage of 25 percent or greater, without 
  specific rainfall criteria.

- Other high impact events deemed critical by the National 
  Weather Service and area fire management agencies.

&&

$$

KSmith

039 
WWUS85 KPIH 300255
RFWPIH

URGENT - FIRE WEATHER MESSAGE
National Weather Service Pocatello ID
855 PM MDT Tue Aug 29 2023

IDZ410-425-427-300400-
/O.EXP.KPIH.FW.W.0009.000000T0000Z-230830T0300Z/
Upper Snake River Valley/Idaho Falls BLM-
Middle Snake River Valley/Twin Falls BLM north of the Snake River-
Goose Creek and Raft River Valley/Southern Sawtooth NF/Twin Falls
BLM south of the Snake River-
855 PM MDT Tue Aug 29 2023

...RED FLAG WARNING WILL EXPIRE AT 9 PM MDT THIS EVENING FOR GUSTY
WINDS AND LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONES 410, 425, 
AND 427...

Temperatures have begun to fall behind the passing cold front this
evening and the humidities are expected to continue to rise as a
result. Wind gusts will remain elevated through the evening 
before gradually decoupling after midnight. As a result, gradually
improving conditions are anticipated through the remainder of the
night and therefore the Red Flag Warning will be allowed to 
expire.

$$

Area Forecast Discussion
National Weather Service Pocatello ID
151 AM MDT Mon Aug 28 2023

.SHORT TERM...Tonight through Tuesday Night

A shortwave ridge will produce dry weather with light winds across
the area today. Temperatures today look comparable to what we saw
for highs on Sunday. Generally highs in the 80s in the valleys. A
cold front will arrive late Tuesday afternoon and Tuesday evening.
Models continue to show isolated to scattered thunderstorms arriving
with the front. Looks like the better chances for storms is north of
a line from Burley to Pocatello. Winds may be the bigger story with
advisory level winds possible across portions of the region. The
better winds are with the front and so the timing of the front may
be what cuts into the chances to reach advisory level winds. There
is at least a 50 percent chance of exceeding advisory levels across
the South Hills into the Magic Valley and Central Mountains including
the Arco Desert. Most of East Idaho has roughly a 30% chance of
meeting advisory levels. Temperatures on Tuesday look very warm
ahead of the front with 90s likely for the Snake Plain and Magic
Valley and 80s in the highlands.

13

.LONG TERM...Wednesday through next Monday.
Following a cold frontal passage on Tuesday, winds will remain
elevated overnight and throughout the day Wednesday as a colder
airmass moves into place supporting a return to dry conditions.
Temperatures will be noticeably cooler for Wednesday with afternoon
highs 14 to 20 degrees cooler over Tuesday in the upper 60s to low
80s. Both the HRRR and RAP smoke models do bring in increased
concentrations of wildfire smoke from wildfires in Oregon and
northern California throughout the day Wednesday associated with
stronger westerly flow.

Dry conditions continue into Thursday as a transitory ridge of high
pressure builds in behind the exiting trough moving through Montana
and North Dakota helping to reintroduce a warming trend headed into
the weekend. As quick as that first trough exits to our northeast, a
secondary trough is expected to quickly fill in behind across
western Canada and the PacNW starting Thursday which with more of a
southwesterly flow component, support isolated showers and
thunderstorms starting Friday through the weekend. This upper level
low will be slow moving in nature Friday and Saturday with no real
steering mechanism to bring it onshore until Sunday into Monday
associated with stronger 500 mb flow in the Gulf of Alaska out of
the west/northwest. This in turn is expected to bring that low
onshore Sunday night into Monday leading to more widespread showers
and thunderstorms coverage and increasingly breezy winds.

Ensemble support amongst the GFS and ECMWF show fairly similar
timing and impacts for this low with a return to more disagreement
beginning Monday night into Tuesday. The main differences surround
the GFS bringing in drier, zonal flow behind the Sunday/Monday
system while the ECMWF shows a secondary wave of energy in the form
of an upper level trough moving through for Tuesday into Wednesday.
The NBM more closely aligns with the ECMWF at this time with the
overall consensus on continued unsettled weather into the first full
week of September as temperatures see a cooling trend as a result of
broad troughing and cloud cover overhead to near normal to below
normal levels. MacKay

&&

.AVIATION...VFR conditions with light winds expected today and
tonight. Typical upslope/downslope winds are expected at SUN/DIJ
this afternoon and evening.

13

&&

.FIRE WEATHER...Following an active weather pattern over the weekend, quiet
conditions return for Monday as high pressure lifts north out of the
Great Basin and temperatures see a warming trend through Tuesday.
The latest HREF probability of thunder for today supports a 10 to 20
percent chance across the ERN Highlands along the Montana and
Wyoming border regions but conditions will remain predominantly dry
outside of any isolated activity that develops this afternoon out of
towering cumulus.

An incoming Pacific trough to the PacNW on Tuesday will mark the
arrival of a cold front working through southern Idaho bringing
widespread breezy to locally gusty winds and isolated to scattered
showers and thunderstorms. Winds will begin increasing early Tuesday
afternoon, peaking between Tuesday evening particularly for Zones
422, 425, and 427 as strong winds shift out of the CNTRL Mountains.
Look for widespread wind gusts in excess of 25 to 30 mph, locally
stronger in that 40 to 50 mph range. The primary hazards with this
cold front will center around a mix of wet and dry isolated to
scattered thunderstorms and low humidities in Zones 422, 425, 427,
and SW 413. While the best CWRs will remain confined to Zones 411,
475, 476, and NRN 422 where a MARGINAL risk (5 to 14 percent) from
the SPC exists of severe wind gusts in excess of 58 mph exists,
drier conditions further south will support near critical to
critical humidities with widespread gusty winds. Starting early
Tuesday afternoon, the HREF ensembles support a 50 to 90 percent
chance of sustained winds greater than 20 mph and humidities less
than 15 percent for Zones 425 and 427 with a 30 to 60 percent chance
for Zones 410 and SW 413. As fuels remain not critical, we will
continue to work with local dispatch centers on the potential for
any product headlines over the coming days.

Following that cold frontal passage on Tuesday, winds will remain
elevated overnight and throughout the day Wednesday as a colder
airmass moves into place supporting a return to dry conditions and
improved humidities. Temperatures will be noticeably cooler for
Wednesday with afternoon highs 14 to 20 degrees cooler over Tuesday
in the upper 60s to low 80s. Both the HRRR and RAP smoke models do
bring in increased concentrations of wildfire smoke from wildfires
in Oregon and northern California throughout the day Wednesday
associated with stronger westerly flow. Southwesterly flow will
reintroduce a warming trend through the start of the weekend as
unsettled weather with showers and thunderstorms returns starting
Friday through early next week. MacKay

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&