987  
FXUS65 KREV 242023  
AFDREV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RENO NV  
123 PM PDT SUN MAY 24 2020  
   
SYNOPSIS
 
 
STRONG HIGH PRESSURE ALOFT WILL BRING SUMMER-LIKE HEAT TO THE REGION  
MUCH OF THIS WEEK WITH RECORD HIGHS POSSIBLE. AFTERNOON THUNDERSTORMS  
COULD FORM STARTING TUESDAY, MAINLY ALONG HIGH TERRAIN. STORMS LOOK  
TO BECOME MORE WIDESPREAD LATE WEEK. STRONGER WINDS, A FEW SHOWERS,  
AND MORE SEASONABLE TEMPERATURES ARE PROJECTED NEXT WEEKEND AS LOW  
PRESSURE APPROACHES FROM THE PACIFIC.  
 

 
   
DISCUSSION
 
 
* CHANGES: NO APPRECIABLE TRENDS IN THE GUIDANCE VS YESTERDAY IN  
REGARDS TO THE COMING WEEK'S HOT TEMPERATURES. FULL STEAM AHEAD  
FOR OUR FIRST LEGIT SUMMER-LIKE HEAT OF THE SEASON. THUNDERSTORM  
CHANCES HAVE MOVED UP A DAY, STARTING TUESDAY IN THE HIGH-COUNTRY.  
NO MEANINGFUL CHANGES MADE TO T-STORM FORECAST WEDNESDAY ONWARD.  
 
* HEAT: REALLY IMPRESSIVE UPPER HIGH BUILDS OVER THE REGION THIS  
WEEK LEADING TO NEAR RECORD TEMPERATURES WEDNESDAY THROUGH  
FRIDAY. PROBABLY THE MOST IMPRESSIVE PIECE OF GUIDANCE THAT  
LEADS ME TO HAVE HIGH CONFIDENCE IN THIS SCENARIO IS THE ECMWF  
EXTREME FORECAST INDEX. THE EFI, WHICH COMPARES THE ENSEMBLE  
FORECAST WITH A "MODEL CLIMATE", IS SHOWING 0.85 TO 0.9 OUT OF 1  
FOR HIGH TEMPERATURES OVER A WIDESPREAD AREA WEDNESDAY THROUGH  
FRIDAY. BASED ON NWS HEAT RISK GUIDANCE, HEAT HEALTH IMPACTS ARE  
LIKELY FOR VULNERABLE POPULATIONS AND THOSE OUTDOORS FOR  
PROLONGED PERIODS OF TIME. ONE MITIGATING FACTOR IN W NEVADA AND  
THE SIERRA - OVERNIGHT LOWS DON'T LOOK EXCESSIVELY WARM SO THAT  
WILL HELP.  
 
* THUNDERSTORMS: AS HEAT DEVELOPS, PRECIPITABLE WATER VALUES ALSO  
INCREASE LEADING TO ISOLATED STORMS AS EARLY AS TUESDAY  
AFTERNOON. MAINLY OVER THE SIERRA BUT CAN'T RULE OUT SOME CELLS  
INTO FAR W NEVADA. WEDNESDAY-THURSDAY STORM CHANCES ARE MORE  
NEBULOUS WITH SLIGHTLY DRIER AIR COMING IN AND LOWER  
THUNDERSTORM POP VALUES FROM THE NBM GUIDANCE. HOWEVER THIS IS  
ALSO WHEN THE ZEPHYR BREEZE WILL START KICKING IN SO A COUPLE  
CONVERGENCE-BASED STORMS ARE POSSIBLE THOSE DAYS. FRIDAY INTO  
SATURDAY IS WHEN THINGS LOOK MORE INTERESTING AS UPPER LOW LIFTS  
INTO CA/NV FROM THE PACIFIC. SUFFICIENT INSTABILITY, SYNOPTIC  
LIFT, AND EVEN SOME SHEAR COULD LEAD TO MORE NUMEROUS STORMS AND  
EVEN A FEW STRONG CELLS. THE ECMWF EFI HAS A CAPE AND SHEAR  
PARAMETER WHICH IS SHOWING ELEVATED VALUES FRIDAY INTO SATURDAY  
FROM NW NEVADA UP INTO OREGON - PERHAPS SUGGESTING A RISK OF  
STRONGER OR EVEN SEVERE STORMS.  
 
* PATTERN SHIFT NEXT WEEK: ENSEMBLE GUIDANCE POINTING TOWARD THE  
LARGE RIDGE AXIS SHIFTING WELL EAST WHILE A GENERAL TROUGH SETS  
UP OFF THE WEST COAST. THIS WOULD LEAD TO COOLER TEMPERATURES,  
BUT PROBABLY JUST CLOSER TO NORMAL FOR EARLY JUNE, AND ALSO KICK  
UP THE WINDS EACH DAY. WE CAN SEE THAT STARTING SATURDAY WITH  
ENHANCED GUSTS IN ECMWF EPS METEOGRAMS DAILY THROUGH MUCH OF  
NEXT WEEK; HOWEVER, NOTHING OVERLY IMPACTFUL IS EXPECTED.  
SHOWERS CAN'T BE RULED OUT EITHER GIVEN PROXIMITY OF THE UPPER  
TROUGH BUT THE GUIDANCE ISN'T SHOWING ANYTHING TOO MENACING.  
 
-CHRIS  
 

 
   
AVIATION
 
 
A BUILDING RIDGE OF HIGH PRESSURE TRANSLATES TO VFR WITH LIGHT  
(LESS THAN 10 KTS) WINDS AND NO CONCERNS THROUGH AT LEAST MID-  
AFTERNOON TUESDAY.  
 
LATER TUESDAY AFTERNOON INTO THE EVENING, A LOW CHANCE (5-10%)  
FOR THUNDERSTORMS EXISTS IN MONO COUNTY AND AROUND THE SWEETWATER  
MOUNTAINS (NORTH OF BRIDGEPORT). NORTHEAST CA, THE SIERRA, AND FAR  
WESTERN NEVADA WILL SEE SOME INCREASE IN THUNDERSTORM CHANCES  
EACH DAY BETWEEN WEDNESDAY AND SATURDAY, MAINLY ISOLATED COVERAGE  
NEAR THE SIERRA INITIALLY THEN EXTENDING FARTHER NORTH INTO  
NORTHEAST CA AND FAR WESTERN NV FRIDAY INTO SATURDAY. THE USUAL  
THUNDERSTORM THREATS ARE EXPECTED: GUSTY OUTFLOW WINDS, SMALL  
HAIL, LIGHTNING, AND HIGHER TERRAIN OBSCURATION IN RAIN.  
 
ONE MORE NOTE: DENSITY ALTITUDES WILL BE RISING SIGNIFICANTLY  
STARTING TUESDAY AS LOWER VALLEY TEMPERATURES SOAR INTO THE 90S,  
WITH AROUND 100 POSSIBLE OUT IN THE BASIN AND RANGE INCLUDING  
KLOL, KNFL, AND KHTH BY THURSDAY AND FRIDAY. -SNYDER  
 

 
   
REV WATCHES/WARNINGS/ADVISORIES
 
 
NV...NONE.  
CA...NONE.  

 
 

 
 
FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...  
HTTP://WEATHER.GOV/RENO  
 
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