434
FXUS65 KREV 180923
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
223 AM PDT THU JUN 18 2026
KEY MESSAGES
* SUMMER-LIKE HEAT WILL MAINTAIN WIDESPREAD MODERATE TO AREAS OF
MAJOR HEATRISK TODAY.
* THUNDERSTORM ACTIVITY INCREASES TODAY AND TOMORROW, PEAKING
FRIDAY. THIS WILL BRING CONCERNS FOR IMPACTS TO FIRE, RECREATION,
AND AVIATION ON BOTH DAYS.
* COOLER AND DRIER WEATHER IS FAVORED TO RETURN OVER THE WEEKEND
FOLLOWED WARMER TEMPERATURES FOR NEXT WEEK.
DISCUSSION
THE LATEST RAP ANALYSIS OF THE UPPER AIR PATTERN THIS MORNING SHOWS
AN UPPER RIDGE OVER THE REGION WITH A SUBTROPICAL TROUGH TRAILING
IT OVER THE PACIFIC. GOING THROUGH TODAY, FORECAST GUIDANCE
PROJECTS THE TROUGH MOVING CLOSER TO THE WEST COAST AND BREAKING
DOWN THE RIDGE. IN THE AFTERNOON, A SHORTWAVE DISTURBANCE MOVES
THROUGH THE FLOW OVER THE CWA AS WELL. WHILE THE RIDGE STILL
REMAINS OVER THE REGION TODAY, WELL-ABOVE NORMAL TEMPERATURES ARE
FORECAST FOR ONE MORE DAY WITH THE NE CA AND W NV VALLEYS HAVING
HIGHS IN THE MIDDLE TO UPPER 90S (SOME PORTIONS OF W NV POSSIBLY
REACHING THE 100 DEGREE MARK) AND SIERRA COMMUNITIES HAVING HIGHS
IN THE LOWER TO HIGH 80S. AS SUCH, THE HEAT ADVISORY FOR THE W NV
BASIN AND RANGE CONTINUES THROUGH EARLY TOMORROW WITH SOME
PORTIONS SEEING MAJOR HEATRISK.
ANOTHER CONCERN FOR TODAY LOOKS TO COME FROM POTENTIAL THUNDERSTORMS
WITHIN THE REGION THIS AFTERNOON. REFS SBCAPE VALUES INCREASE TO
AROUND 500-1000 J/KG IN THE SIERRA AND THE SIERRA FRONT (HIGHER
VALUES WEST OF THE SIERRA CREST). WITH THIS INSTABILITY, THE
INCREASED WARMTH IN THE AFTERNOON PROVIDING LIFT, AND PWAT VALUES
UP TO AROUND 0.6 INCHES: THESE PORTIONS OF THE CWA HAVE AROUND A
15-35% CHANCE FOR SHOWERS AND THUNDERSTORMS TODAY WITH THE WINDOW
OPENING AROUND 1-2 PM PDT. THE STORMS WILL PROVIDE INCREASED FIRE
WEATHER CONCERN WITHIN THE SIERRA FRONT TODAY (PLEASE REFER TO
THE FIRE WEATHER SECTION BELOW OR THE RED FLAG WARNING IN EFFECT
TODAY FOR MORE INFORMATION). BRIEF BOUTS OF HEAVY RAIN COULD OCCUR
WITH THESE STORMS, BUT NOT ANTICIPATING MAJOR FLOODING ISSUES AS
THE GROUND PROBABLY CAN ABSORB A GOOD AMOUNT OF RAIN WITH THE
RECENT DRY CONDITIONS. WHEN LOOKING AT MODEL FORECAST SOUNDINGS,
THE SIERRA FRONT ALSO WILL HAVE UP TO AROUND 1500-1800 J/KG OF
DCAPE ALLOWING FOR STORMS TO PRODUCE INCREASED OUTFLOW GUSTS UP TO
~50 MPH LATER TODAY. PLEASE BE WEATHER AWARE TODAY ESPECIALLY IF
YOU HAVE OUTDOOR PLANS AND REMEMBER: WHEN THUNDER ROARS, GO
INDOORS!
FOR FRIDAY, MODELS SHOW THE TROUGH MAKING ITS WAY OVER THE W CONUS.
THIS PATTERN ALOFT WILL ALLOW SHOWER AND STORM CHANCES WITHIN THE
REGION TO INCREASE TO AROUND 25-65% FOR MOST OF THE CWA FOR
TOMORROW. RECENT RUNS OF THE CAMS SHOW SOME MORNING SHOWERS
DEVELOPING IN NE CA, BUT STRONGER STORMS THEN BEGINNING TO
DEVELOP IN THE QUAD COUNTIES REGION (ESPECIALLY ALONG THE PINE NUT
MOUNTAINS) BY AROUND NOON. THESE STORMS LOOK TO MOVE NORTH-
NORTHEAST AND MAY NOT EXIT THE CWA COMPLETELY UNTIL THE LATE
EVENING. THESE STORMS COULD BE A BIT WETTER WITH CURRENT QPF
VALUES IN W NV RANGING BETWEEN A TRACE TO AROUND 0.25 INCHES. BUT
SOME STORMS COULD ALSO BE ON THE DRY SIDE WITH THE SPC SHOWING A
10% DRY THUNDERSTORM FOR MOST OF THE CWA ON FRIDAY. A FIRE WEATHER
WATCH IS IN EFFECT IN AREAS SEEING THE HIGHER CHANCES FOR FIRE
WEATHER CONCERN ON FRIDAY THOUGH THIS AREA COULD EXPAND. WITH
SIMILAR CONVECTIVE PARAMETERS AS THOSE FORECAST FOR TODAY, FRIDAY
WILL SEE SIMILAR STORM HAZARDS INCLUDING GUSTY ERRATIC OUTFLOWS TO
50 MPH, LIGHTNING OUTSIDE OF RAIN CORES, FAST MOVING STORMS, AND
HEAVY RAIN UNDER STORM CORES. WILL BE MONITORING TRENDS IN CASE
THE ENVIRONMENT BECOMES MORE FAVORABLE FOR SEVERE WEATHER. BLOWING
DUST IS ALSO POSSIBLE NEAR DESERT SINKS AND PLAYAS IF STRONGER
GUSTS OCCUR IN THE NV BASIN AND RANGE. PLEASE HAVE A WAY TO
RECEIVE THE LATEST WEATHER UPDATES ON FRIDAY ESPECIALLY IF YOU
HAVE RECREATION AND TRAVEL PLANS.
WHILE DAYTIME HIGH TEMPERATURES ARE FORECAST TO DECREASE AROUND 5-10
DEGREES ON FRIDAY, THEY BECOME CLOSEST TO MID-JUNE NORMALS ON
SATURDAY. SATURDAY'S FORECAST HIGHS FOR THE NE CA AND NV VALLEYS
WILL BE IN THE MIDDLE TO UPPER 80S WHILE THE SIERRA COMMUNITIES
WILL BE IN THE MIDDLE TO UPPER 70S RANGE. FORECAST GUIDANCE THEN
PROJECTS THE TROUGH MOVING EASTWARD AND AWAY FROM THE CWA ON
SUNDAY FOLLOWED BY HIGH PRESSURE BUILDING OVER THE SW CONUS GOING
INTO THE MIDDLE OF NEXT WEEK. THIS SIGNALS DRY CONDITIONS FOR NEXT
WEEK WITH TEMPERATURES WARMING AGAIN TO WHERE MODERATE HEATRISK
IS SEEN WITHIN W NV BEGINNING ON MONDAY. -078
AVIATION
DENSITY ALTITUDE CONCERNS MAY CONTINUE TODAY AT TERMINALS IN NE CA
AND W NV DUE TO INCREASED HEATING. THE MAIN CONCERN TODAY EXPECTS
TO BE WITH SHOWERS AND STORMS DEVELOPING WITHIN THE REGION STARTING
AROUND 18/21-22Z. THE SIERRA AND SIERRA FRONT HAVE AROUND A 15-35%
CHANCE FOR PRECIPITATION TODAY. MVFR CONDITIONS ARE POSSIBLE AT
MOST TAF SITES SHOULD A STORM DEVELOP NEARBY. STORMS MAY CONTAIN
INCREASED GUSTY OUTFLOW WINDS, BRIEF PERIODS OF HEAVY RAIN AND
LIGHTNING. TERRAIN OBSCURATION, LLWS AND TURBULENCE MAY ALSO BE
PRESENT NEAR STORM CORES. ANOTHER ROUND OF SHOWERS AND STORMS IS
FORECAST FOR TOMORROW WITH INCREASED CHANCES AND COVERAGE WHICH
EXPECT TO BRING ADDITIONAL AVIATION CONCERNS. -078
FIRE WEATHER
FIRE WEATHER CONCERNS INCREASE AS THE THUNDERSTORM POTENTIAL WITHIN
THE REGION RISES TODAY AND TOMORROW. ANTECEDENT HOT AND DRY
CONDITIONS WITH POOR OVERNIGHT RECOVERIES HAVE HELPED IN DRYING
FUELS FURTHER WHICH ALSO RAISES FIRE DANGER.
STORMS WILL MOVE QUICKLY ONCE DEVELOPED, WITH A MIX OF WET AND DRY
STORM MODES. THIS INCREASES POTENTIAL FOR DRY LIGHTNING STRIKES
OUTSIDE OF WET STORM CORES AS WELL AS DRY STORMS THAT PRODUCE MORE
LIGHTNING THAN MOISTURE. GUSTY, ERRATIC OUTFLOWS OF 50+ MPH ARE
POSSIBLE, INCREASING THE THREAT OF RAPID WIND DIRECTION SHIFTS.
A RED FLAG WARNING IS IN EFFECT TODAY ACROSS THE SIERRA FRONT FROM 1
PM TO 10 PM. A FIRE WEATHER WATCH STILL STANDS FOR FRIDAY, IN EFFECT
FROM 8 AM THROUGH 11 PM. HRICH/078
REV WATCHES/WARNINGS/ADVISORIES
NV...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
NVZ458.
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 10 PM PDT THIS
EVENING NVZ420-421.
HEAT ADVISORY UNTIL 5 AM PDT FRIDAY NVZ004.
FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
NVZ423.
CA...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
CAZ270-278.
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