257
FXUS65 KREV 041952
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
1252 PM PDT TUE AUG 4 2026
KEY MESSAGES
* A PROLONGED PERIOD OF TRIPLE-DIGIT HEAT ACROSS WESTERN NV AND
EASTERN CA VALLEYS PREVAILS THROUGH THIS WEEKEND.
* SMOKE AND HAZE FROM REGIONAL WILDFIRES COULD BRING IMPACTS TO
AIR QUALITY AT TIMES THROUGH THIS WEEK.
* DRY CONDITIONS PERSIST IN MOST AREAS THIS WEEK, BUT LOW-END
ISOLATED SHOWER AND THUNDER CHANCES MAY RETURN FRIDAY INTO THIS
WEEKEND FOR PARTS OF THE EASTERN SIERRA AND WESTERN NV.
DISCUSSION
AFTER A SHORT BREAK YESTERDAY, TEMPERATURES RESUME THEIR CLIMB TO
NEAR 100 DEGREES FOR LOWER ELEVATIONS THIS AFTERNOON, THEN PUSH
ABOVE THE CENTURY MARK FROM WEDNESDAY THROUGH THIS WEEKEND. THE
LATEST GUIDANCE IS A TOUCH LOWER ON THE HIGH END OF THE
TEMPERATURE RANGE, WITH PEAK FORECAST HIGHS OF 104 DEGREES FOR
US-95 SITES IN WEST CENTRAL NV AND 100-103 DEGREES FOR OTHER
VALLEYS ACROSS WESTERN NV/EASTERN CA FROM THURSDAY-SATURDAY.
OVERNIGHT TEMPERATURES WILL GENERALLY FALL TO THE 60S, EXCEPT
AROUND 70 DEGREES FOR TYPICALLY WARMER SITES SUCH AS FERNLEY AND
HAWTHORNE. GIVEN THE LONG DURATION OF THIS EVENT, WE WILL EXTEND
THE CURRENT HEAT ADVISORY THROUGH SUNDAY MORNING. HOWEVER, WE ARE
NOT EXPECTING EXTREME HEAT (HIGHS TYPICALLY NEAR OR ABOVE 105
DEGREES AND/OR MORE WIDESPREAD LOWS ABOVE 70 DEGREES FOR OUR AREA)
SO THE EXTREME HEAT WATCH WILL DROP OUT AND BE REPLACED WITH THIS
ADVISORY. AS MENTIONED FREQUENTLY IN THE PAST WEEK, BE SAFE AND
SMART IF PLANNING OUTDOOR ACTIVITIES FOR THE REST OF THIS WEEK AND
WEEKEND, AND CONSIDER ALTERNATIVES THAT AVOID THE PEAK AFTERNOON
TEMPS/SUN EXPOSURE, ESPECIALLY IF MORE SENSITIVE TO HEAT. FOR
THOSE HEADING TO HIGHER ELEVATIONS ABOVE 6000 FEET INCLUDING THE
SIERRA, IT WILL STILL BE QUITE WARM WITH HIGHS NEAR OR ABOVE 90
DEGREES.
SMOKE AND HAZE FROM PACIFIC NW FIRES WILL LINGER THROUGH TONIGHT
AND THEN RECEDE WEDNESDAY AS AFTERNOON SW-W WINDS RETURN WITH
TYPICAL ZEPHYR-TYPE GUSTS NEAR 25 MPH AND BRIEF GUSTS TO 30 MPH,
AND CONTINUING AT SIMILAR SPEEDS DAILY THROUGH SATURDAY. HOWEVER,
A NEW ACTIVE FIRE IN THE FOOTHILLS EAST OF STOCKTON CA (GANN
FIRE) IS PROJECTED TO PUSH SMOKE TOWARD THE SIERRA LATER TODAY.
THE LATEST HIGH-RES GUIDANCE IS INDICATING A LARGER AREA OF
SMOKE/HAZE FROM THIS FIRE AFFECTING MORE OF THE SIERRA AND WESTERN
NV WEDNESDAY AS SOUTHWEST FLOW INCREASES. THIS KEEPS THE RISK OF
REDUCED AIR QUALITY IN PLACE, ALTHOUGH THE MAGNITUDE OF AIR
QUALITY IMPACTS WILL DEPEND ON HOW ACTIVE THE GANN FIRE BURNS IN
UPCOMING DAYS.
OVERALL DRY CONDITIONS REMAIN WITH US THIS WEEK, ALTHOUGH
AFTERNOON CUMULUS BUILDUPS ARE PROJECTED TO RETURN MAINLY SOUTH
OF US-50 THURSDAY. HOWEVER, BY FRIDAY AFTERNOON THERE ARE HINTS OF
INCREASING MOISTURE (PW VALUES RISING TO 0.6-0.8") AND EARLY RUNS
OF HIGHER RESOLUTION GUIDANCE ARE HINTING AT ISOLATED CONVECTION.
WHILE FORCING MAY NOT VERY EVIDENT, ABUNDANT DAYTIME HEATING AND
CONVERGENCE FROM TERRAIN FEATURES AND THE AFTERNOON ZEPHYR COULD
LEAD TO A FEW STRAY SHOWERS/T-STORMS (UP TO 10% CHANCE) FORMING
NEAR/EAST OF THE SIERRA CREST AND EXTENDING NORTHWARD INTO PARTS
OF WESTERN NV EAST OF RENO/CARSON CITY. A FURTHER INCREASE IN
MOISTURE IS SHOWING UP SATURDAY LEADING TO MORE CLOUD COVER
ESPECIALLY SOUTH OF US-50 AND INTO WEST CENTRAL NV, BUT ISOLATED
SHOWERS AND T-STORMS CAN'T BE RULED OUT AGAIN.
FOR SUNDAY, HIGHS COULD STILL TOP 100 DEGREES AS THE HIGH PRESSURE
OVER THE GREAT BASIN ONLY SHOWS A SLIGHT RETREAT/WEAKENING TREND.
THEN FROM MONDAY ONWARD, A LOW PRESSURE TROUGH REACHING THE
PACIFIC NW COAST IS MORE LIKELY TO PUSH THE RIDGE FARTHER AWAY
FROM WESTERN NV. THIS SHOULD BRING TEMPERATURES DOWN BUT AFTERNOON
WINDS COULD TREND UPWARD, LEADING TO INCREASED FIRE WEATHER
CONCERNS. MJD
AVIATION
* FOR THE REST OF TODAY, W-NW WIND GUSTS 15-20 KT MAINLY BETWEEN
23-03Z AT THE WESTERN NV TERMINALS, AROUND 20 KT FOR KMMH
BETWEEN 21-03Z, AND LIGHTER WINDS AT KTRK/KTVL. FOR WEDNESDAY,
SW-W WIND GUSTS INCREASE TO 20-25 KT FOR THE MAIN TERMINALS
STARTING 20-22Z AND DIMINISHING BETWEEN 03-05Z, WITH SIMILAR
WIND CONDITIONS CONTINUING THROUGH LATE THIS WEEK.
* VFR CONDITIONS PREVAIL THROUGH THIS WEEK, ALTHOUGH SMOKE AND
HAZE FROM FIRES ACROSS THE WESTERN US MAY BRING PERIODS OF
REDUCED SLANTWISE VISIBILITY TO AREA TERMINALS THROUGH AT LEAST
WEDNESDAY. PROLONGED HEAT WEDNESDAY THROUGH SATURDAY WILL RESULT
IN INCREASED DENSITY ALTITUDE CONCERNS AREAWIDE. MJD
REV WATCHES/WARNINGS/ADVISORIES
NV...HEAT ADVISORY FROM 8 AM WEDNESDAY TO 8 AM PDT SUNDAY NVZ001-
003>005.
CA...HEAT ADVISORY FROM 8 AM WEDNESDAY TO 8 AM PDT SUNDAY CAZ070-071.
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