964
FXUS65 KREV 012325 AAA
AFDREV
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
425 PM PDT TUE SEP 1 2026
UPDATE
WITH LATEST GUIDANCE CONSISTENT IN KEEPING GUSTY WINDS GOING
THROUGH WEDNESDAY, WE EXTENDED THE CURRENT LAKE WIND ADVISORY.
EVEN FOR TONIGHT, BREEZY TO GUSTY WINDS WILL CONTINUE WITH ONLY
OCCASIONAL LULLS. WINDS SHOULD DIMINISH LATE WEDNESDAY EVENING OR
OVERNIGHT, ALTHOUGH ANOTHER ROUND OF INCREASED WINDS COULD BRING
UNFAVORABLE LAKE CONDITIONS AGAIN THURSDAY AFTERNOON. MJD
KEY MESSAGES
* CRITICAL FIRE WEATHER CONDITIONS CONTINUE TODAY FOR NORTHEAST CA
AND PARTS OF WESTERN NV DUE TO GUSTY WINDS AND LOW HUMIDITIES.
* COOLER AND BREEZY CONDITIONS PERSIST THROUGH THE WEEK, WITH
RAIN CHANCES TO NORTHEAST CA AND NORTHWEST NV THURSDAY AND
FRIDAY.
* UNCERTAINTY REMAINS REGARDING THE TRAJECTORY OF TROPICAL
MOISTURE, WHICH COULD INCREASE SHOWER/THUNDERSTORM CHANCES
EARLY NEXT WEEK.
PREVIOUS DISCUSSION
/ISSUED 143 PM PDT TUE SEP 1 2026/
DISCUSSION...
THE DRY COLD FRONTAL PASSAGE IS WELL UNDERWAY ACROSS THE REGION THIS
MORNING, BRINGING GUSTY WINDS AND LOW HUMIDITIES. SURFACE
OBSERVATIONS SHOW SOUTHWEST TO WEST WINDS 15-25 MPH ACROSS
WESTERN NEVADA VALLEYS AND SIERRA COMMUNITIES, WITH GUSTS UP TO
35-45 MPH, ESPECIALLY IN THE TAHOE BASIN AND ALONG EXPOSED RIDGES.
RIDGETOP GUSTS COULD REACH 60-70 MPH THROUGH THE AFTERNOON. THESE
WINDS, COMBINED WITH RELATIVE HUMIDITY VALUES DROPPING INTO THE
10-20% RANGE ACROSS MUCH OF THE FORECAST AREA, ARE LEADING TO
CRITICAL FIRE WEATHER CONDITIONS. RED FLAG WARNINGS REMAIN IN
EFFECT FOR NORTHEAST CA AND NORTHWEST NV, WITH LAKE WIND
ADVISORIES FOR AREA LAKES. BLOWING DUST IS ALSO POSSIBLE IN DESERT
PLAYAS AND SINKS, LIKELY REDUCING VISIBILITIES. TEMPERATURES
TODAY WILL REMAIN WELL BELOW SEASONAL AVERAGES, GENERALLY IN THE
60S FOR SIERRA COMMUNITIES AND 70S TO LOW 80S FOR WESTERN NEVADA
VALLEYS.
WEDNESDAY WILL SEE CONTINUED GUSTY CONDITIONS, WITH AFTERNOON
GUSTS OF 25-40 MPH STILL POSSIBLE, PARTICULARLY ACROSS THE SIERRA
AND NORTHERN PORTIONS OF THE FORECAST AREA. TEMPERATURES WILL
REMAIN COOL, 10-15 DEGREES BELOW NORMAL, WITH HIGHS IN THE 50S AND
60S FOR THE SIERRA AND 70S FOR WESTERN NEVADA VALLEYS. THE MAIN
CHANGE FOR WEDNESDAY NIGHT INTO THURSDAY IS THE INCREASING CHANCE
FOR PRECIPITATION. A LOW PRESSURE SYSTEM TRACKING INLAND WILL
BEGIN TO BRING MOISTURE INTO NORTHEAST CA AND NORTHWEST NV.
PRECIPITATION CHANCES INCREASE TO 10-30% WEDNESDAY NIGHT, THEN
JUMPING TO 70-80% BY THURSDAY MORNING. THIS INCOMING RAIN WILL BE
SHOWERY IN NATURE, WITH THE HIGHEST PROBABILITIES FOCUSED ON
LASSEN COUNTY AND NORTHERN WASHOE COUNTY. FARTHER SOUTH INTO THE
EASTERN SIERRA AND WESTERN NEVADA, PRECIPITATION CHANCES REMAIN
LOW (LESS THAN 10%) ON THURSDAY.
FRIDAY ONWARD WE'LL SEE PERSISTENT TROUGHING ALONG THE WEST
COAST, KEEPING TEMPERATURES COOLER THAN NORMAL, AND INTRODUCING
INCREASING UNCERTAINTY REGARDING A POTENTIAL TROPICAL MOISTURE
INTERACTION EARLY NEXT WEEK. FRIDAY AND SATURDAY ARE EXPECTED TO
BE RELATIVELY DRY FOR MOST OF THE REGION. NBM GUIDANCE GENERALLY
SHOWS LOW PRECIPITATION PROBABILITIES (BELOW 10%) ACROSS THE
REGION, THOUGH SOME SIERRA LOCATIONS LIKE MAMMOTH LAKES SHOW
ISOLATED HIGHER CHANCES (UP TO 15% ON SATURDAY). TEMPERATURES
WILL REMAIN COOL, WITH HIGHS IN THE 60S-70S FOR THE SIERRA AND
70S-80S FOR VALLEYS. BREEZY AFTERNOONS ARE STILL POSSIBLE, BUT
WINDS ARE EXPECTED TO BE LIGHTER THAN EARLIER IN THE WEEK.
THE MAIN FORECAST CHALLENGE FOR THE LATTER HALF OF THE LONG TERM
(SUNDAY INTO LABOR DAY) REVOLVES AROUND THE POTENTIAL INTERACTION OF
REMNANT MOISTURE FROM A TROPICAL SYSTEM (INVEST 95E) IN THE EASTERN
PACIFIC. FOR WESTERN NV, NBM GUIDANCE FOR SUNDAY AND LABOR DAY
SHOWS A NOTABLE INCREASE IN PRECIPITATION CHANCES. POPS JUMP TO
15-30%. THIS SUGGESTS THAT WHILE A DIRECT HIT IS UNLIKELY, THERE
IS A GROWING POTENTIAL FOR ENHANCED SHOWERS AND THUNDERSTORMS FROM
THIS REMNANT MOISTURE. GIVEN THE ONGOING UNCERTAINTY, CONFIDENCE
IN SPECIFIC PRECIPITATION AMOUNTS AND COVERAGE REMAINS LOW, BUT
THE TREND FOR INCREASED ACTIVITY IS EVIDENT IN THE BLEND OF
MODELS. TEMPERATURES WILL REMAIN COOL TO MILD, GENERALLY IN THE
60S-70S FOR HIGHS.
-JUSTIN
AVIATION...
VFR CONDITIONS PERSIST TODAY WITH AFTERNOON GUSTS OF 25-30 KTS.
FL100 WINDS OUT OF THEW SW INCREASE TO 40-45 KTS THIS AFTERNOON,
BRINGING LLWS AND MOUNTAIN WAVE TURBULENCE TO ALL SIERRA AND
SIERRA FRONT SITES. AREAS OF REDUCED VISIBILITY FROM BLOWING DUST
MAY IMPACT KLOL, KNFL, KHTH AS WELL AS AVIATION OPERATIONS ON THE
BLACK ROCK DESERT TODAY.
-JUSTIN
FIRE WEATHER...
TODAY WILL POSE THE HIGHEST CONCERN FOR CRITICAL FIRE WEATHER
CONDITIONS AS HUMIDITY VALUES DROP TO 12-20% AND AFTERNOON WIND
GUSTS INCREASE UP TO 40 MPH. AS SUCH, A RED FLAG WARNING HAS BEEN
ISSUED FOR THE NORTHERN SIERRA FRONT AND EXTENDING NORTHWARD INTO
NE CA EAST OF CA-139, NORTHERN WASHOE COUNTY, AND THE SURPRISE
VALLEY IN MODOC COUNTY. WINDS WILL BE PRIMARILY OUT OF THE
SOUTHWEST, SHIFTING WESTERLY/NORTHWESTERLY AFTER SUNSET.
WINDS WILL REMAIN ELEVATED WEDNESDAY (30 TO 45 MPH) BUT HIGHER
HUMIDITY VALUES AND INCREASING CHANCES FOR PRECIPITATION WILL
LIMIT FIRE CONCERNS FOR MOST AREAS. BREEZY AFTERNOONS CONTINUE
THROUGH FRIDAY, WITH PRECIP CHANCES AND COOLER TEMPERATURES
MITIGATING THE FIRE THREAT FOR THE REMAINDER OF THE WEEK.
-GIRALTE/JUSTIN
REV WATCHES/WARNINGS/ADVISORIES
NV...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING NVZ458.
RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING NVZ420.
LAKE WIND ADVISORY UNTIL 5 AM PDT THURSDAY NVZ002>004.
CA...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING CAZ270-278.
LAKE WIND ADVISORY UNTIL 5 AM PDT THURSDAY CAZ071-072.
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