317
FXUS65 KREV 182123
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
223 PM PDT SAT JUL 18 2026
KEY MESSAGES
* ELEVATED FIRE WEATHER CONCERNS LINGER THIS AFTERNOON IN
NORTHEAST CA AND NORTHWEST NV WITH BREEZY WINDS AND LOW
HUMIDITY.
* SEASONABLY WARM CONDITIONS AND AREAS OF INCREASED CLOUD COVER
PREVAIL THROUGH THIS WEEKEND WITH ISOLATED SHOWERS AND
THUNDERSTORMS NEAR THE EASTERN SIERRA EACH AFTERNOON.
* PERIODS OF MONSOONAL MOISTURE WILL KEEP SHOWER AND THUNDERSTORM
CHANCES WITH POTENTIAL FOR LOCALIZED HEAVY RAIN NEXT WEEK. BEST
OVERALL STORM CHANCES FAVOR MONDAY AFTERNOON THROUGH WEDNESDAY.
DISCUSSION
A SWATH OF THICKER MID TO HIGH LEVEL CLOUD COVER OVERNIGHT THROUGH
THIS MORNING BROUGHT SPOTTY LIGHT RAIN SHOWERS AND ISOLATED
LIGHTNING TO PARTS OF NORTHEAST CA, WITH STREAKS OF VIRGA ALSO
SEEN OUTSIDE OUR WINDOWS EARLIER TODAY. THE SUBTLE SHORTWAVE ALOFT
THAT PRODUCED THIS MORE EXTENSIVE CLOUD DECK WAS NOT RESOLVED
VERY WELL WITH YESTERDAY'S HIGHER RESOLUTION GUIDANCE.
FOR THE REST OF TODAY, OVERALL CLOUD COVER FROM US-50 NORTHWARD
WILL DECREASE, WITH A SHORT PERIOD OF DRIER CONDITIONS DROPPING
HUMIDITY TO BETWEEN 12-16% IN NORTHEAST CA AND FAR NORTHWEST NV.
AFTERNOON BREEZES WITH GUSTS TO 25 MPH IN THESE AREAS WILL PRODUCE
A FEW HOURS OF ELEVATED FIRE WEATHER CONCERNS UNTIL SUNSET. SOUTH
OF US-50, A SMALL AREA OF INSTABILITY LEAVES OPEN A WINDOW FOR
ISOLATED SHOWERS AND SHORT-LIVED T-STORMS (UP TO 15% CHANCE)
MAINLY BETWEEN 3-8 PM FOR PARTS OF MONO, MINERAL AND LYON
COUNTIES.
OVERNIGHT INTO SUNDAY MORNING, ANOTHER STREAM OF INCREASED
MOISTURE RETURNS TO NORTHEAST CA, BRINGING ANOTHER CHANCE OF LIGHT
RAIN SHOWERS NEAR OR AFTER DAYBREAK THROUGH LATE MORNING. ALSO
GIVEN THE FEW LIGHTNING STRIKES THAT OCCURRED EARLIER TODAY IN
EASTERN LASSEN COUNTY, THERE'S A 10% OR LESS CHANCE FOR A FEW
STRIKES AGAIN AROUND 18Z SUNDAY, BUT FOCUSING TOWARD THE WESTERN
PARTS OF LASSEN COUNTY.
FOR THE REST OF SUNDAY THROUGH SUNDAY NIGHT, LOW TO MID LEVEL S-SE
FLOW AND THE SOUTHWARD DRIFT OF THE HIGH PRESSURE RIDGE FROM THE
ROCKIES TO THE FOUR CORNERS REGION BRING A GRADUAL EXPANSION OF
DEEPER MONSOONAL MOISTURE. THIS COULD BRING A BIT MORE FAVORABLE
SETUP FOR ISOLATED PM SHOWERS AND T-STORMS AGAIN ACROSS THE
EASTERN SIERRA OF MONO COUNTY EASTWARD TO ADJACENT PARTS OF
SOUTHERN LYON AND MINERAL COUNTIES. HOWEVER, THE CONFIDENCE IS
RELATIVELY LOW AS THE HIGHER RESOLUTION GUIDANCE SCENARIOS ARE NOT
ALL ON BOARD WITH THE INSTABILITY BEING SUFFICIENT TO SUPPORT
STORM CELL GROWTH. IF THE CLOUD COVER BECOMES TOO WIDESPREAD AFTER
THE INITIAL STORMS FORM, WE COULD SEE A RELATIVELY QUICK
TRANSITION TO LIGHTER RAIN SHOWERS FOR SUNDAY EVENING AND NIGHT AS
THIS ACTIVITY MOVES NORTH AND WEST. OVERALL WE ONLY HAVE CHANCES
FOR MEASURABLE RAIN AT LESS THAN 10% THROUGH SUNDAY NIGHT, BUT
PASSING SPRINKLES COULD OCCUR ACROSS NEARLY ANY PORTION OF
WESTERN NV/NORTHEAST CA.
THE MONSOONAL MOISTURE PUSH STILL APPEARS TO PEAK FROM MONDAY
AFTERNOON THROUGH TUESDAY WITH INCREASED RISK FOR GREATER SHOWER
AND T-STORM COVERAGE. FOR MONDAY THE BEST INSTABILITY AND
POTENTIAL FOR SHOWERS AND T-STORMS CURRENTLY FAVORS AREAS SOUTH OF
US-50, ALTHOUGH ISOLATED STORMS COULD EXTEND FARTHER NORTH ACROSS
WESTERN NV INTO MONDAY EVENING WITH LIGHTER SHOWERS EXTENDING
OVERNIGHT.
TUESDAY IS WHERE THE CONCERNS INCREASE FOR MORE WIDESPREAD
RAINFALL AFFECTING A GREATER EXTENT OF EASTERN CA-WESTERN NV,
SLOWER STORM MOTIONS, ABUNDANT MOISTURE AND POCKETS OF INSTABILITY
TO HOLD THE SHOWER/STORM ACTIVITY TOGETHER. THIS COULD BE A
SIMILAR OUTCOME AS LAST MONDAY WHEN MORE AREAS GOT WET, ALTHOUGH
THE OVERDEVELOPING CLOUD SCENARIO CONTINUES TO LURK AS THE PW
VALUES PUSH ABOVE 1" IN MUCH OF THE REGION. AT THIS TIME, WE'RE
GIVING AN EARLY HEADS-UP NOTICE FOR POTENTIAL LOCALIZED FLASH
FLOOD RISKS PEAKING ON TUESDAY.
LATER IN THE WEEK AND INTO NEXT WEEKEND, THE MONSOON PUSH APPEARS
TO BE GRADUALLY SHIFTING EASTWARD WITH STORM RISKS DECREASING
INITIALLY FOR NORTHEAST CA WEDNESDAY AND THEN NORTHWEST NV
SOUTHWARD ACROSS TAHOE AND FAR WESTERN NV INCLUDING THE RENO-
CARSON VICINITY FROM THURSDAY ONWARD. HOWEVER, THIS HAS BEEN
FLUCTUATING WITH EACH DAY'S GUIDANCE AND THE SHOWER/STORM CHANCES
COULD HANG ON LONGER, ESPECIALLY IN WEST CENTRAL NV ALONG AND EAST
OF US-95 AND SOUTHWARD TO MONO COUNTY. MJD
AVIATION
VFR CONDITIONS ARE EXPECTED THIS WEEKEND FOR ALL AREA TERMINALS,
WITH PERIODS OF INCREASED MID-HIGH LEVEL CLOUD COVER THROUGH
SUNDAY. SW-W WIND GUSTS THIS AFTERNOON AND SUNDAY MAINLY 15-20 KT
EXCEPT 20-25 KT AT KRNO STARTING A BIT LATER COMPARED TO RECENT
DAYS (AFTER 22Z) THEN WINDING DOWN BETWEEN 03-05Z. A FEW SHOWERS
MAY DEVELOP NEAR KMMH EACH AFTERNOON TODAY AND SUNDAY BUT ONLY
10-15% CHANCE OF LIGHTNING WITHIN 5 NM OF THE TERMINAL SITE.
FOR THE EARLY PART OF NEXT WEEK, SHOWER AND T-STORM CHANCES
INCREASE MAINLY SOUTH OF US-50 MONDAY, WITH BEST OVERALL CHANCES
AT THE MAIN TERMINALS ON TUESDAY. IMPACTS MAY INCLUDE LOCALLY
HEAVY RAINFALL, MORE FREQUENT LIGHTNING AND OUTFLOW GUSTS OF 30+
KT. MJD
REV WATCHES/WARNINGS/ADVISORIES
NV...NONE.
CA...NONE.
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