101
FXUS65 KREV 261659 AAA
AFDREV
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
959 AM PDT MON MAY 26 2025
UPDATE
A WEAK UPPER LOW WHICH BROKE OFF FROM LAST NIGHT'S TROUGH PASSAGE
IS MOVING TOWARD THE CENTRAL-SOUTHERN SIERRA THIS AFTERNOON.
LATEST HIGH-RES GUIDANCE IS SHOWING AN AREA OF INSTABILITY AND
FORCING ASSOCIATED WITH THIS LOW, WHICH LOOKS SUFFICIENT TO
PRODUCE ISOLATED SHOWERS WITH EMBEDDED THUNDER (AROUND 15% CHANCE)
MAINLY ACROSS MONO-SOUTHERN MINERAL COUNTIES THIS AFTERNOON, MOST
LIKELY BETWEEN 2-8 PM. A MORE REMOTE 5-10% CHANCE FOR A STRAY
CELL COULD EXTEND FARTHER NORTH ALONG THE EASTERN SIERRA TO THE
TAHOE BASIN. FOR THOSE PARTICIPATING IN OUTDOOR RECREATION THIS
AFTERNOON, KEEP AN EYE TO THE SKY AND HAVE ACCESS TO SHELTER IF
CUMULUS CLOUDS SHOW INCREASED VERTICAL GROWTH. MJD
PREVIOUS DISCUSSION
/ISSUED 205 AM PDT MON MAY 26 2025/
KEY MESSAGES...
* ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS ARE EXPECTED ACROSS
THE REGION FOR THE MEMORIAL DAY HOLIDAY.
* A WARMING TREND IS IN THE FORECAST LEADING TO NEAR RECORD
WARMTH AND MODERATE HEATRISK BY THE MIDWEEK ONWARD.
* THERE IS A NON-ZERO CHANCE OF AFTERNOON SHOWERS AND THUNDERSTORMS
IN THE SIERRA AND NORTHEAST CALIFORNIA ON WEDNESDAY.
DISCUSSION...
THE LATEST RAP UPPER AIR ANALYSIS SHOWS THE CWA BETWEEN A PACNW
TROUGH AND A RIDGE TO EAST ALLOWING FOR A SOUTHWESTERLY FLOW ALOFT
THIS MORNING. CURRENT IR SATELLITE IMAGERY SHOWS A GOOD AMOUNT OF
HIGH CLOUDS OVER MOST OF THE CWA ESPECIALLY IN THOSE AREAS ALONG THE
CA/NV BORDER WHILE THE LATEST SURFACE OBSERVATIONS SHOW DRY CONDITIONS
ACROSS THE CWA. MODEL GUIDANCE GOING THROUGH TODAY SHOWS A WEAK UPPER
LOW DEVELOPING OUT OF THE TROUGH AND OVER THE CWA DURING THE AFTERNOON
AND EVENING HOURS. CLOSER TO THE SURFACE, MODELS FORECAST A WEAK COLD
FRONT MOVING THROUGH THE CWA TODAY ALLOWING FOR SLIGHTLY COOLER (BUT
STILL ABOVE NORMAL) DAYTIME HIGHS ON MEMORIAL DAY COMPARED TO THOSE
TEMPERATURES SEEN OVER THE WEEKEND. THE WESTERN NV VALLEYS LOOK TO
SEE TEMPERATURES IN THE UPPER 70S TO LOWER 80S RANGE WHILE SIERRA
COMMUNITIES HAVE HIGHS IN THE MIDDLE 60S TO LOWER 70S RANGE IN THE
FORECAST. WINDS LOOK TO SHIFT TO OUT OF THE NORTH-NORTHWEST BY THE
EVENING HOURS BEHIND THE COLD FRONT, BUT WILL BE RELATIVELY LIGHTER
COMPARED TO THOSE SEEN LAST NIGHT. CHANCES FOR PRECIPITATION LOOK TO
BE LOW TODAY THOUGH MONO AND MINERAL COUNTIES MAY SEE ~5-10% CHANCE
FOR AN ISOLATED SHOWER IN THE EVENING.
GOING THROUGH THE REST OF THE WEEK, A WARMING TREND IS EXPECTED WITH
WESTERN NV SEEING HIGHS IN THE 90S RETURN TO THE FORECAST BY WEDNESDAY
AND IN THE UPPER 90S (POSSIBLY KNOCKING ON THE DOOR OF TRIPLE DIGITS
AS AREAS AROUND FALLON HAVE A 30-50% CHANCE TO REACH 100 DEGREES) BY
SATURDAY AS A REX BLOCK SETS UP IN THE REGION LATER THIS WEEK. MODELS
CONTINUE TO SHOW HIGH PRESSURE BUILDING OVER THE PACNW WHILE A CUT-
OFF LOW DANCES OFF THE COAST OF THE BAJA PENINSULA DURING THE WEEK.
AS A RESULT, THE LATEST NWS HEATRISK SHOWS MODERATE HEATRISK STARTING
ON WEDNESDAY WITHIN WESTERN NV THAT GRADUALLY BECOMES MORE WIDESPREAD
BY SATURDAY. SO PLEASE CONSIDER PREPARING FOR THE UPCOMING NEAR RECORD
(AND MORE JULY-LIKE) TEMPERATURES BY VISITING WEATHER.GOV/SAFETY/HEAT
FOR SOME HEAT SAFETY TIPS.
THE UPPER AIR PATTERN CALLS FOR MOSTLY DRY CONDITIONS IN THE CWA WITH
THE AFOREMENTIONED UPPER AIR PATTERN. FOR FIRE WEATHER CONCERNS, DAYTIME
MINIMUM RELATIVE HUMIDITY VALUES IN THE CWA DO LOOK TO ENTER THE SINGLE
DIGITS TO THE MIDDLE TEENS RANGE BY TUESDAY AND WEDNESDAY THAT LAST
THROUGH THE REST OF THE WEEK WITH NOT HAVING THE BEST OVERNIGHT RECOVERIES.
ONE SAVING GRACE IS THAT AREA WINDS ARE FORECAST TO BE ON THE LIGHTER
SIDE WITH SOME AFTERNOON BREEZES THAT WILL NOT PROMOTE CRITICAL FIRE
WEATHER CONDITIONS.
AS FOR PRECIPITATION CHANCES LATER THIS WEEK, THERE IS QUITE SOME
DISAGREEMENT MIDWEEK ON WEDNESDAY BETWEEN THE LATEST RUNS OF FORECAST
MODELS WHEN IT COMES TO POTENTIAL PM ISOLATED SHOWERS AND THUNDERSTORMS,
SO OPTING TO KEEP POPS IN NORTHWESTERN CA AND IN THE SIERRA UNDER 10%
WITH THIS FORECAST PACKAGE. WILL CONTINUE TO MONITOR FOR BETTER AGREEMENT
GOING FORWARD, BUT LOW CONFIDENCE IS SEEN AT THIS TIME DUE TO MODELS
DIFFERING IN THEIR SOLUTIONS. THE NEXT CHANCE FOR POSSIBLE PRECIPITATION
LOOKS TO BE IN THE BEGINNING OF NEXT WEEK AS LONG TERM MODELS SHOW
A PATTERN CHANGE WITH THE LOW NEAR THE BAJA PENINSULA MOVING TOWARDS
THE REGION. THIS MAY RESULT IN A COLD FRONT MOVING THROUGH THE
AREA CAUSING TEMPERATURES TO TREND DOWNWARD A BIT AS WELL. -078
AVIATION...
VFR CONDITIONS ARE EXPECTED FOR AREA TERMINALS ON THE MEMORIAL DAY
HOLIDAY WITH SOME LIGHT AFTERNOON BREEZES ACROSS THE REGION. DRY
CONDITIONS ARE ALSO IN THE FORECAST THIS WEEK THOUGH THERE MAY BE
SOME ISOLATED SHOWER CHANCES (LESS THAN 10%) IN THE SIERRA ON
WEDNESDAY. A SIGNIFICANT WARM-UP AT THE END OF THE WEEK MAY
PRESENT DENSITY ALTITUDE ISSUES INTO NEXT WEEKEND. -013/078
REV WATCHES/WARNINGS/ADVISORIES
NV...NONE.
CA...NONE.
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