Red Flag Warning 6, NWS Reno, NV

229 
WWUS85 KREV 251616
RFWREV

URGENT - FIRE WEATHER MESSAGE
National Weather Service Reno NV
916 AM PDT Thu Jul 25 2024

CAZ271-260400-
/O.EXA.KREV.FW.W.0006.240725T2000Z-240726T0400Z/
Western Lassen, Eastern Plumas, and Eastern Sierra Counties-
916 AM PDT Thu Jul 25 2024

...RED FLAG WARNING IN EFFECT FROM 1 PM THIS AFTERNOON TO 9 PM
PDT THIS EVENING FOR GUSTY WINDS AND LOW HUMIDITY FOR NORTHEASTERN
CALIFORNIA AND NORTHWESTERN NEVADA...

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

* CHANGES...Upgraded the Fire Weather Watch to a Red Flag 
  Warning.

* Affected Area...Fire Weather Zone 271 Western Lassen, Eastern 
  Plumas and and Eastern Sierra Counties.

* Winds...Southwest to west 15 to 25 mph with gusts 30 to 35 mph.

* Humidity...Minimum 8 to 14 percent.

* Duration...4 to 6 hours.

* Impacts...The combination of gusty winds and low humidity can 
  cause fire to rapidly grow in size and intensity before first 
  responders can contain them. Gusty winds may also impact 
  existing holdovers from previous storms, causing them to 
  quickly spread.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Avoid outdoor activities that can cause a spark near dry
vegetation, such as yard work, target shooting, or campfires.
Follow local fire restrictions. Check weather.gov/reno for
updates and livingwithfire.info for preparedness tips.

&&

$$

CAZ270-278-NVZ458-260400-
/O.CON.KREV.FW.W.0006.240725T2000Z-240726T0400Z/
Surprise Valley California-Eastern Lassen County-
Northern Washoe County-
916 AM PDT Thu Jul 25 2024

...RED FLAG WARNING REMAINS IN EFFECT FROM 1 PM THIS AFTERNOON TO
9 PM PDT THIS EVENING FOR GUSTY WINDS AND LOW HUMIDITY FOR
SURPRISE VALLEY, EASTERN LASSEN COUNTY, AND NORTHERN WASHOE
COUNTY...

* CHANGES...Upgraded the Fire Weather Watch to a Red Flag 
  Warning.

* Affected Area...Fire Weather Zone 270 Surprise Valley 
  California, Fire Weather Zone 278 Eastern Lassen County and 
  Fire Weather Zone 458 Northern Washoe County.

* Winds...Southwest to west 20 to 25 mph with gusts 30 to 35 mph.

* Humidity...Minimum 8 to 14 percent.

* Duration...4 to 6 hours.

* Impacts...The combination of gusty winds and low humidity can 
  cause fire to rapidly grow in size and intensity before first 
  responders can contain them. Gusty winds may also impact 
  existing holdovers from previous storms, causing them to 
  quickly spread.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Avoid outdoor activities that can cause a spark near dry
vegetation, such as yard work, target shooting, or campfires.
Follow local fire restrictions. Check weather.gov/reno for
updates and livingwithfire.info for preparedness tips.

&&

$$

http://weather.gov/reno

Area Forecast Discussion
National Weather Service Reno NV
141 AM PDT Wed Jul 24 2024

.SYNOPSIS...

* Thunderstorms will bring locally heavy rain and flash flood
  potential along with strong outflow gusts today.

* Storms become more isolated over west central NV Thursday, as
  drier air brings an end to storms from Friday into next week.

* Gusty southwest winds and more seasonal temperatures return
  Thursday and Friday with locally critical fire weather
  conditions.

&&

.DISCUSSION...

Tuesday's storms were mainly concentrated from western Mono County
and Lyon/E Douglas/Storey and western Churchill counties, with
additional storm activity across Washoe County north of I-80 to
the OR border. Plenty of lightning was noted (including a few new
fire starts) with several cells producing heavy rainfall based on
radar estimates, but seemingly missing the majority of ground-
based rain gauge and observation sites.

Today is expected to have the most widespread coverage of
thunderstorms with the most abundant push of moisture (PW values
between 0.90-1.25"), including more areas of western NV. It will
be the final chance for the main urban areas including Reno-
Sparks, Carson City and Minden to get appreciable rain through at
least the remainder of July. We will expand the flood watch to
include these cities due to the more favorable setup for sustained
convection. While increasing mid-level S/SW flow will bring
somewhat faster storm motions, it will also allow for more
organized storm activity with cells lasting longer. Convergence
along the afternoon zephyr, outflow boundaries and/or terrain
features will provide multiple focus areas for repeated formation
of cells, which may train over the same locations and bring longer
periods of enhanced rainfall rates, especially where the flood
watch is in effect. Areas north and east of the flood watch
(including far northeast CA and northwest-west central NV) will
have a greater risk of stronger outflow gusts (50+ mph) and hail,
but still can't rule out some pockets of heavy rainfall as well.

For Thursday, an increased push of drier and more stable air from
a trough over the Pacific Northwest will confine storms to west
central NV mainly from US-95 eastward and southeast Mono County,
with more isolated coverage compared to today. Winds will also be
on the increase Thursday and Friday (see the fire weather section
for more details), with t-storm chances decreasing to less than
10% from Friday through early next week.

Temperatures will begin to edge downward today from the recent
run of triple digit heat (Reno just set a new record for most 100+
degree days in any month--15 days), with a more notable cooling
Thursday-Friday. Highs this weekend are trending a little below
late July averages--near 90 for western NV and mid-upper 70s for
Sierra communities. MJD

&&

.AVIATION...

* Thunderstorms will again be the primary threat this afternoon
  and early evening, mainly between 20-04Z overall although
  favoring the earlier hours of this time frame for the
  Sierra/Tahoe terminals, and the later hours for west central NV.
  Periods of heavy rain could bring MVFR/IFR conditions while
  lightning and outflow wind gusts of 35+ kt are more likely with

* A drier pattern returns from Thursday onward with isolated
  cells/outflow winds hanging on for one more day along the US-95
  corridor (KLOL-KNFL-KHTH). SW-W winds increase each afternoon
  Thurs-Fri with gusts 25-30 kt across most of the main
  terminals. MJD

&&

.FIRE WEATHER...

* Smoke from the Mill fire SW of Portola is most likely to spread
  across eastern Plumas/southeast Lassen counties and parts of
  western NV each afternoon today-Thursday. The HRRR smoke
  trajectory model is keeping most of the smoke plume north of the
  Reno-Sparks urban area for the next couple of days, affecting
  areas around Pyramid Lake and extending into Pershing and
  Churchill counties. This trajectory assumes similar smoke output
  and no disruptions from t-storm outflows.

* Thunderstorms today will be mainly wet, but isolated dry strikes
  are again a risk for parts of northeast CA-northwest NV where
  storm motions will be faster and sub-cloud moisture isn't quite
  as abundant.

* For Thursday-Friday, thunderstorm chances decrease but a drier
  air mass combined with increasing winds will produce areas of
  critical fire weather conditions, especially for northeast CA
  and northwest NV where a Fire Weather Watch remains in effect.
  Recent/ongoing fires and additional lightning holdovers in these
  areas are at risk for more rapid fire spread as these winds
  increase. South of the watch area, isolated lightning fire
  ignitions that aren't extinguished by rain are also at risk for
  increased spread rates with the drier and breezy conditions
  Thursday-Friday. MJD

&&

.REV Watches/Warnings/Advisories...
NV...Fire Weather Watch from Thursday afternoon through Thursday
     evening NVZ458.

     Flood Watch through this evening NVZ001-003.

CA...Fire Weather Watch from Thursday afternoon through Thursday
     evening CAZ270-278.

     Flood Watch through this evening CAZ073.

&&