176
FXUS65 KREV 090918
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
218 AM PDT THU JUL 9 2026
KEY MESSAGES
* BREEZY WINDS AND LOW HUMIDITY WILL POSE ELEVATED FIRE WEATHER
AND RECREATION CONCERNS FRIDAY AND SATURDAY AFTERNOONS.
* INCREASING TEMPERATURES INTO THE WEEKEND WILL BRING AREAS OF
MODERATE TO LOCALLY MAJOR HEATRISK FOR SATURDAY.
* A MONSOON-TYPE PATTERN MAY INCREASE THE POTENTIAL FOR SHOWERS
AND THUNDERSTORMS NEXT WEEK.
DISCUSSION
HIGH PRESSURE CURRENTLY OVER SOUTHERN CA/AZ IS PROJECTED TO
MIGRATE TO THE FOUR CORNERS REGION BY SATURDAY. THE WEAK LOW
PRESSURE TROUGH THAT WAS LOCATED NEAR THE WEST COAST SINCE TUESDAY
RETREATS NORTHWARD TODAY BEFORE BECOMING RE-ESTABLISHED ALONG THE
COAST FOR FRIDAY-SATURDAY. THE RESULTING EFFECT OF THIS WEATHER
PATTERN WILL BE A SLIGHT DECREASE IN THE PM BREEZES TODAY, BEFORE
RETURNING TO INCREASED GUSTS BEYOND THE TYPICAL FRIDAY- SATURDAY
(SEE THE FIRE WEATHER SECTION BELOW FOR MORE DETAILS). MEANWHILE,
A SLOW WARMING TREND WILL RESUME, WITH ABOVE AVERAGE TEMPERATURES
PEAKING SATURDAY IN THE TRIPLE DIGITS FOR MANY WESTERN NV VALLEYS
AND NEAR 90 FOR SIERRA COMMUNITIES, RESULTING IN MODERATE TO
ISOLATED MAJOR HEATRISK FOR LOWER ELEVATIONS ON SATURDAY. WHILE
DRY CONDITIONS ARE EXPECTED TO PREVAIL FOR THE NEXT THREE DAYS, A
FEW HIGHER RESOLUTION GUIDANCE SCENARIOS SHOW INCREASED CUMULUS
BUILDUPS AND ISOLATED SHOWERS (UP TO 10% CHANCE) FORMING IN FAR
NORTHEAST CA-NORTHWEST NV THIS AFTERNOON.
LATER IN THE WEEKEND THROUGH EARLY-MID NEXT WEEK, THE PATTERN
BEGINS TO SHIFT WITH FLOW ALOFT BECOMING MORE SW-S OVER THE SIERRA
SUNDAY, WITH POTENTIAL FOR DEEPER SOUTHERLY FLOW AT TIMES FROM
MONDAY-WEDNESDAY. THIS WOULD ALLOW FOR MONSOON-TYPE MOISTURE TO
PUSH INTO THE EASTERN SIERRA AND PARTS OF WESTERN NV, WITH
INCREASING INSTABILITY LEADING TO SHOWERS AND T-STORMS MAINLY IN
THE AFTERNOON, BUT ALSO COULD LINGER OVERNIGHT. WHILE THE HIGH
PRESSURE RIDGE IS MOST LIKELY TO BE CENTERED OVER THE CENTRAL US
WITH A LOW PRESSURE TROUGH NEAR OR JUST OFF THE WEST COAST, THE
EVENTUAL LOCATION OF THESE FEATURES (ALONG WITH UPPER LEVEL
DISTURBANCES ROTATING AROUND THE RIDGE'S WESTERN PERIPHERY) WILL
DETERMINE THE EXTENT OF THE T-STORM THREAT. IN GENERAL, THE MOST
FAVORED AREAS FOR STORMS EXTEND FROM MONO-MINERAL COUNTIES INTO
THE US-95 CORRIDOR OF WEST CENTRAL NV, WITH DECREASING STORM
CHANCES TO THE NORTH AND WEST.
TEMPERATURES BEGIN A DOWNWARD TREND STARTING SUNDAY WITH HIGHS
DIPPING TO NEAR MID-JULY AVERAGES (LOWER-MID 90S FOR WESTERN NV
VALLEYS AND LOWER 80S NEAR THE SIERRA) FOR EARLY NEXT WEEK. A
WARMUP MAY RETURN LATER NEXT WEEK, BUT CONFIDENCE REMAINS ON THE
LOWER SIDE WITH HOW MUCH HEAT RETURNS TO THE REGION AS WE GET TO
THE SECOND HALF OF JULY. MJD
AVIATION
* WIDESPREAD VFR ACROSS THE REGION THROUGH THIS WEEKEND WITH SW-W
GUSTS 20-25 KTS FOR THE MAIN TERMINALS (EXCEPT A BIT LIGHTER FOR
KTRK/KTVL) THIS AFTERNOON MAINLY BETWEEN 22-04Z, DOWN SLIGHTLY
COMPARED TO YESTERDAY. WINDS EDGE UPWARD FRIDAY-SATURDAY, WITH
AFTERNOON GUSTS 25-30 KTS FOR THE MAIN TERMINALS. MJD
FIRE WEATHER
* CONTINUED DRY AFTERNOONS WILL PREVAIL INTO THIS WEEKEND, WITH
MINIMUM RH VALUES DIPPING TO THE SINGLE DIGITS FOR MUCH OF
WESTERN NV (DOWN TO NEAR 5% AT TIMES ALONG/EAST OF US-95) AND
EASTERN LASSEN COUNTY, WITH 10-15% FOR THE EASTERN SIERRA/TAHOE
BASIN AND NEAR THE OR BORDER. OVERNIGHT HUMIDITY RECOVERY WILL
BE POOR FOR MUCH OF WESTERN NV AND SOME MIDSLOPE/THERMAL BELT
REGIONS, WITH MAXIMUM RH VALUES ONLY AROUND 20-30%.
* WHILE WINDS TODAY EASE BACK A BIT, SW-W FLOW INCREASES OVER THE
SIERRA FRIDAY WITH 700 MB WINDS INCREASING TO 25-30 KT. THIS
WOULD INCREASE THE POTENTIAL FOR AFTERNOON WIND GUSTS PUSHING
INTO THE 30-35 MPH RANGE, PRODUCING ELEVATED TO LOCALLY CRITICAL
CONDITIONS ACROSS PARTS OF EASTERN LASSEN/NORTHERN WASHOE
COUNTIES SOUTHWARD INTO THE WESTERN NV SIERRA FRONT. THE
DURATION OF THE GUSTY WINDS/LOW RH MEETING CRITICAL LEVELS STILL
LOOKS LIMITED, BUT A FEW SITES COULD SEE THESE CONDITIONS OCCUR
FOR MORE THAN 3 HOURS.
* FOR SATURDAY AFTERNOON, SIMILAR WIND SPEEDS RETURN WITH THE
ENHANCED (25-30 KT) 700 MB FLOW SHIFTING NORTHWARD. THIS WOULD
RESULT IN AREAS NEAR THE OR BORDER HAVING THE BEST POTENTIAL FOR
GUSTY WINDS/LOW RH MEETING CRITICAL LEVELS FOR 3 OR MORE HOURS,
WHILE A SHORTER DURATION OF THESE COMBINED DRY AND GUSTY
CONDITIONS EXTENDS SOUTHWARD TO THE WESTERN NV SIERRA FRONT. MJD
REV WATCHES/WARNINGS/ADVISORIES
NV...NONE.
CA...NONE.
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