849
FXUS65 KREV 171931
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
1231 PM PDT FRI JUL 17 2026
KEY MESSAGES
* INCREASED BREEZES AND LOW HUMIDITY WILL LEAD TO ELEVATED FIRE
WEATHER CONCERNS THIS AFTERNOON, ESPECIALLY FOR NORTHEAST CA
AND NORTHWEST NV.
* SEASONABLY WARM AND MAINLY DRY CONDITIONS PREVAIL THROUGH THIS
WEEKEND, WITH INCREASED CLOUD COVER SATURDAY NIGHT AND SUNDAY.
* PERIODS OF MONSOONAL MOISTURE RETURN NEXT WEEK, RENEWING
CHANCES FOR SHOWERS AND THUNDERSTORMS, WITH POTENTIAL FOR
LOCALIZED HEAVY RAIN.
DISCUSSION
ANOTHER DRY AND WARM DAY PREVAILS FOR EASTERN CA AND WESTERN NV
WITH A MODEST SW FLOW ALOFT OVER THE SIERRA WHILE AN AREA OF LOW
PRESSURE OFF THE NORTHWEST WASHINGTON COAST MOVES SLOWLY
NORTHWARD INTO SW CANADA. MEANWHILE, A LARGE HIGH PRESSURE RIDGE
CONTINUES TO EXTEND FROM THE ROCKIES TO THE CENTRAL US. WE'LL
STILL HAVE ELEVATED FIRE WEATHER CONCERNS ACROSS NORTHEAST CA AND
FAR NORTHWEST NV THIS AFTERNOON AS WIND GUSTS INCREASE TO 25-30
MPH WITH BRIEF GUSTS TO 35 MPH WHILE HUMIDITY BOTTOMS OUT IN THE
8-12% RANGE. FOR SATURDAY, THE WIND GUST SPEEDS EDGE DOWNWARD A
BIT WHILE HUMIDITY WON'T BE QUITE AS LOW, BUT IT REMAINS IMPORTANT
TO AVOID ACTIVITIES THAT CAN CAUSE A SPARK, WITH ONGOING FIRES IN
NORTHEAST CA.
AS THE WEEKEND PROGRESSES, WE'LL START TO SEE A GRADUAL SHIFT TO
A MONSOON-TYPE PATTERN, WITH THE FIRST INDICATIONS BEING THE
ARRIVAL OF MORE WIDESPREAD MID-HIGH CLOUDS LATE SATURDAY THROUGH
SUNDAY. THERE ARE LOW PROBABILITIES (10% OR LESS) FOR A FEW NARROW
SHOWER BANDS FORMING SATURDAY NIGHT INTO SUNDAY MORNING ACROSS
PARTS OF NORTHEAST CA AND FAR NORTHWEST NV, WITH A FEW HIGHER
RESOLUTION GUIDANCE SOURCES NOW INDICATING THIS POTENTIAL. WITH
LOW LEVELS REMAINING RELATIVELY DRY, THE MOST LIKELY OUTCOME WOULD
BE VIRGA OR JUST A FEW SPRINKLES REACHING THE GROUND. SIMILAR
LOW-END CHANCES (NEAR 10%) FOR LIGHT SHOWERS COULD RETURN SUNDAY
AFTERNOON AND EXTEND FROM NORTHEAST CA INTO THE SIERRA AND
MINERAL COUNTY, BUT CONFIDENCE IS ON THE LOWER SIDE FOR ANY
MEANINGFUL RAIN AMOUNTS REACHING THE GROUND, WITH NO SIGNIFICANT
FORCING EVIDENT ON THE LATEST GUIDANCE.
NEXT WEEK FROM MONDAY ONWARD, THE LARGE HIGH PRESSURE RIDGE IS
PROJECTED TO DRIFT SOUTHWARD AND EXTEND FROM THE FOUR CORNERS
REGION TO THE SOUTH CENTRAL US. THIS WILL BRING A MORE SOUTHERLY
FLOW ALOFT, WITH DEEPER MOISTURE ADVANCING INTO EASTERN CA/WESTERN
NV. FOR MONDAY AFTERNOON, THE BEST INSTABILITY AND POTENTIAL FOR
SHOWERS AND T-STORMS CURRENTLY FAVORS AREAS SOUTH OF US-50. THEN
FOR TUESDAY-WEDNESDAY, THE RISK FOR SHOWERS AND AFTERNOON/EVENING
T-STORMS EXPANDS NORTHWARD ACROSS THE REGION AS SURFACE DEW POINTS
RISE INTO THE 40S AND LOWER 50S. WHILE THIS MOIST PATTERN CAN
LEAD TO STORMS CAPABLE OF PRODUCING HEAVY RAINFALL AND INCREASE
CONCERNS FOR LOCALIZED FLASH FLOODING, A COMMON LIMITING FACTOR IF
FORCING ISN'T SUFFICIENT IS AN OVERDEVELOPMENT OF THICKER CLOUD
COVER. THIS IN TURN CUTS OFF THE INSTABILITY AND LEAVES MORE
AREAS WITH PERIODS OF MAINLY LIGHT RAIN, AND COOLER DAYTIME HIGHS
BY UP TO 10 DEGREES.
LATER NEXT WEEK, THE ENSEMBLE GUIDANCE SPREAD INCREASES WITH A
NEAR EQUAL SPLIT BETWEEN A RETURN OF DRIER SOUTHWEST FLOW VS. A
CONTINUING INFLUENCE OF DEEPER MONSOONAL MOISTURE INTO THE REGION.
AS A RESULT, OVERALL CONFIDENCE IS LOWER AND THE CURRENT FORECAST
WILL TAKE A MID-RANGE APPROACH WITH A GRADUAL DECREASE OF SHOWER
AND T-STORM CHANCES INITIALLY FOR NORTHEAST CA THEN TO
NORTHWEST/FAR WESTERN NV AND THE TAHOE BASIN, BUT NOT YET
CLEARING OUT OF WEST CENTRAL NV OR MONO COUNTY BY NEXT FRIDAY.
ASIDE FROM THE AFOREMENTIONED POTENTIAL FOR SEVERAL DEGREES OF
COOLING IF WE GET A DAY OR TWO WITH THICKER CLOUD COVER AND/OR
PATCHY RAIN, DAYTIME TEMPERATURES FOR THE UPCOMING WEEK WILL
GENERALLY REMAIN NEAR MID-LATE JULY AVERAGES. THIS KEEPS HIGHS IN
THE 90S FOR LOWER ELEVATIONS, WITH A FEW SITES IN WEST CENTRAL NV
WITHIN REACH OF 100 DEGREES ESPECIALLY SUNDAY AND MONDAY. SIERRA
COMMUNITIES CAN EXPECT HIGHS MAINLY IN THE 80S. HOWEVER, OVERNIGHT
LOWS WILL BE WARMER THAN AVERAGE DUE TO INCREASED MOISTURE AND
CLOUD COVER STARTING SATURDAY NIGHT, MAINLY IN THE 60S-LOWER 70S
FOR THE LOWER ELEVATIONS AND UPPER 40S-50S FOR THE SIERRA. MJD
AVIATION
VFR CONDITIONS CONTINUE ACROSS ALL MAIN TERMINALS THROUGH THIS
WEEKEND, ALTHOUGH MID AND HIGHER LEVEL CLOUD COVER INCREASES
SATURDAY NIGHT-SUNDAY. MAIN CONCERN TODAY AND SATURDAY WILL BE
AFTERNOON SW-W WIND GUSTS UP TO 25 KTS (EXCEPT A BIT LIGHTER FOR
KTVL/KTRK) RAMPING UP BETWEEN 21-23Z AND WINDING DOWN BETWEEN
03-05Z. MJD
REV WATCHES/WARNINGS/ADVISORIES
NV...NONE.
CA...NONE.
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