274  
FXUS65 KPSR 100029  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
529 PM MST TUE AUG 9 2022  
   
UPDATE
 
 
UPDATED AVIATION SECTION.  
 

 
   
SYNOPSIS
 
 
ELEVATED CHANCES FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE THE  
REST OF THE WEEK AND INTO EARLY NEXT WEEK. OCCASIONALLY HEAVY  
RAINFALL, LOCALIZED FLASH FLOODING, GUSTY WINDS AND LOCALIZED  
BLOWING DUST REMAIN LIKELY THROUGH EARLY NEXT WEEK. HIGH  
TEMPERATURES WILL REMAIN BELOW TO NEAR NORMAL THROUGH THE FORECAST  
PERIOD.  
 

 
   
DISCUSSION
 
 
THE MIDLEVEL MONSOON RIDGE REMAINS OPTIMALLY LOCATED NEAR THE S-CENT  
ROCKIES WITH MOIST E UNDERCUTTING FLOW THROUGH THE MID-UPPER  
LEVELS ALOFT. WV IMAGERY REVEALS A VERY MOIST AIRMASS ACROSS THE  
REGION WITH A NUMBER OF E WAVES/INVERTED TROUGHS PUSHING W AND NW  
INTO/THROUGH VARIOUS PARTS OF THE REGION INCLUDING N, E AND S-SE  
AZ, SE CA/LA PAZ CTY, WHERE GOES IMAGERY AND RADAR ALSO INDICATED  
AN AREA OF SCATTERED SHOWERS AND STORMS, WITH LOCALIZED FLASH  
FLOODING OCCURRING THIS AFTERNOON, INCLUDING I-10 E AND W OF  
BLYTHE.  
 
EARLY AFTERNOON RADAR ALSO SHOWED WIDELY ISOLATED TO  
SCATTERED DISTANT THUNDERSTORMS ACROSS THE HIGH TERRAIN OF N, E  
AND S-SE AZ. BOTH THE E AZ/W NM AND S-SE AZ STORMS WERE  
ASSOCIATED WITH ADDITIONAL, POSSIBLY LINKED E WAVE(S) ADVANCING  
FROM THOSE AREAS. THE LATEST ACARS SOUNDINGS SHOWED AN  
ANOMALOUSLY MOIST AIRMASS WITH PW MAINTAINING NEAR 1.7->1.9" WHILE  
MESOSCALE ANALYSIS INDICATED PW OF 1.5->2" AND MEAN W OF 10->14  
G/KG ACROSS SW-W AND S-CENT AZ AND INTO SE CA. MU AND SB CAPE HAD  
ALSO INCREASED TO >1.7-1.8K J/KG AROUND PHOENIX AND >2K J/KG  
ACROSS THE W DESERTS.  
 
IN A SEEMINGLY VIRTUAL REPEAT OF YESTERDAY, HREF MEMBERS STILL FAVOR  
PRONOUNCED CONVECTION WITH LOCALLY HEAVY RAINFALL DEVELOPING THIS  
AFTERNOON ACROSS S GILA CTY AND NEAR GLOBE AND BURN SCAR AREAS  
BEFORE DESCENDING INTO THE LOWER DESERTS AND PARTS OF THE PHOENIX  
METRO DURING THE EVENING HOURS. WITH THE REGIONAL FLOOD WATCH NOW  
UNDERWAY THROUGH LATE TONIGHT, AND WITH THE WPC DAY 1 ERO  
INDICATING THE LARGE "SLIGHT RISK" AREA, ANY CONVECTION THAT  
DEVELOPS WILL HAVE SOUND POTENTIAL TO PRODUCE LOCALLY HEAVY  
RAINFALL AS WELL AS LOCALIZED FLASH FLOODING.  
 
ALSO LIKE YESTERDAY THE HRRR HAS ONCE AGAIN BECOME AN OUTLIER AND  
HAS AGAIN BACKED OFF ON THAT SCENARIO BY BOTH DELAYING AND  
WEAKENING THE CONVECTION COMING OFF OF THE HIGH TERRAIN THIS  
EVENING. THIS IS THE RESULT OF A FESTERING MCV, LIGHT SHOWERS AND  
CLOUDY/MOSTLY CLOUDY CONDITIONS THAT SIGNIFICANTLY DELAYED SURFACE  
HEATING THIS MORNING ACROSS MOST OF THE PHOENIX METRO. THIS  
SUPPORTED ELEVATED LEVELS OF CIN WELL INTO THE DAY AROUND PHOENIX.  
 
HOWEVER THE 12Z HREF ENSEMBLE STILL INDICATED A GUSTY SE OUTFLOW  
THIS EVENING PUSHING INTO THE PHOENIX METRO AND N PINAL AS WELL AS  
COLLIDING OUTFLOW SIGNALS LATE TONIGHT W-SW OF PHOENIX. THE  
POTENTIAL FOR PATCHY BLOWING DUST MOVING NW REMAINS POSSIBLE,  
ALTHOUGH REMAINS MOST LIKELY FOR N PINAL CTY AND THE SE-E PHX  
METRO VALLEY WHERE THERE IS A 10-30% CHANCE OF MAX SUSTAINED STORM  
OUTFLOW WIND SPEEDS OF >35 MPH THIS EVENING.  
 
ALSO LIKE A REPEAT OF YESTERDAY'S PROGS, TOMORROW THE HREF AND  
ENSEMBLES ARE IN AGREEMENT ON AN INCREASE IN STORM CHANCES AND  
COVERAGE FROM E TO W ACROSS THE REGION WITH POPS INCREASING TO NEAR  
50% FOR PHOENIX AND THE LOWER DESERTS AND THE E AZ HIGH COUNTRY, AND  
20-30% FOR SW AZ AND SE CA. SOME HREF MEMBERS START WITH SOME  
SHOWER ACTIVITY W OF PHOENIX IN THE WED MORNING HOURS MOVING IN FROM  
IN S-SE AZ. HOWEVER THE MAIN CONVECTION WILL LIKELY START IN E-SE AZ  
ASSOCIATED WITH THE NEXT E WAVE(S) AND WILL PUSH INTO THE PHOENIX  
METRO AND THE LOWER DESERTS WED EVENING.  
 
FOR WED EVENING THE HREF INDICATES AN EVEN BETTER 30->50% CHANCE  
OF MAX SUSTAINED STORM OUTFLOW WIND SPEEDS OF >35 MPH FROM BOTH  
THE S-SE AND E AND LOCALLY DENSE BLOWING DUST. ALSO INDICATED IS A  
>10% CHANCE OF SUSTAINED MAX OUTFLOW WINDS >57 MPH ALONG THE  
INFAMOUS I-10 DUST CORRIDOR JUST SOUTH OR THE CWA (OR S OF ELOY  
AZ NEAR PICACHO PEAK). THIS WOULD LIKELY BE FOLLOWED BY LOCALLY  
HEAVY RAINFALL AND ADDITIONAL LOCALIZED FLASH FLOODING IN THE HIGH  
COUNTRY AND THE LOWER DESERTS.  
 
LOOKING MORE BROADLY FOR THE REST OF THE WEEK AND INTO THE  
WEEKEND, MAJOR WEATHER FEATURES INCLUDE THE MID LEVEL ANTICYCLONE  
CENTERED NEAR FOUR CORNERS AND A RATHER DEEP UPPER LEVEL LOW OFF  
THE NORTHERN CA COAST. THE LOW IS EXPECTED TO LIFT NORTH,  
AMPLIFYING THE ANTICYCLONE AND SHIFTING THE CENTER A LITTLE  
FURTHER NORTH AND EAST THROUGH THE WEEK. THIS WILL ENHANCE THE  
UNDERCUTTING EASTERLY FLOW ACROSS SOUTHWEST. EPS/GEFS/CMC RESOLVE  
THIS, WITH H5 HEIGHTS ANOMALOUSLY HIGHER OVER THE PACIFIC  
NORTHWEST, INDICATING AN EVEN BROADER EASTERLY FLOW IS LIKELY BY  
THIS WEEKEND. UNTIL THEN, POPS REMAIN ELEVATED WITH CONTINUED  
CHANCES OF SHOWERS AND THUNDERSTORMS EACH DAY ACROSS THE ENTIRE  
CWA.  
 
SEVERAL EPS AND GEFS MEMBERS LATCH ONTO A SIGNIFICANT WAVE MOVING  
THROUGH THE SOUTHWEST AROUND SATURDAY (GIVE OR TAKE A DAY FOR  
UNCERTAINTY). THE EPS-BASED EFI QPF DATA HAS AN INTERESTING  
SIGNAL IN THAT THE MAJORITY OF MEMBERS ARE NOT FORECASTING  
CLIMATOLOGICALLY HIGH RAINFALL, BUT THERE ARE A SMALL MINORITY OF  
MEMBERS THAT ARE PREDICTING QPF OUTSIDE THE MODEL CLIMATE FOR  
AUGUST. THIS ALIGNS WITH AN AXIS OF ENHANCED INSTABILITY AND  
MOISTURE EMANATING NORTH OUT OF THE GULF OF CALIFORNIA AND ARCING  
NNE INTO SOUTHERN IDAHO. DIGGING A LITTLE DEEPER THROUGH CLUSTER  
ANALYSIS OF THE GLOBAL ENSEMBLES, THE DETAILS OF THIS WILL REALLY  
DEPEND ON THE EVOLUTION OF THE UPPER LEVEL LOW TO OUR NORTHWEST. A  
DEEPER SOLUTION (FAVORED BY 1/3 EPS AND 1/2 CMC BUT JUST ONE GEFS  
MEMBERS) WOULD INCREASE WIND FIELDS AND MOISTURE FLUX RESULTING  
IN GREATER PRECIP POTENTIAL. EVEN THE NBM IS INDICATING NON-ZERO  
CHANCES FOR 24-HR QPF OF 1"+.  
 
GIVEN THE INCREASED CLOUDINESS AND MOISTURE THROUGH THE FORECAST  
PERIOD, HIGH TEMPERATURES WILL LIKELY (~80%) REMAIN BELOW DAILY  
NORMALS. TEMPERATURE VARIABILITY IS QUIET HIGH, ESPECIALLY AROUND  
THE WEEKEND WITH THE POTENTIAL INFLUX OF EVEN HIGHER MOISTURE AND  
CLOUDS (NBM IQR FOR SUNDAY'S HIGH TEMPERATURE IS 96-105F).  
HEATRISK LEVELS WILL REMAIN IN THE MODERATE CATEGORY ACROSS SE CA  
THROUGH THE WEEK WITH LOW EXPECTED ACROSS MOST OF ARIZONA - THUS  
SOME HEAT IMPACTS ARE POSSIBLE ESPECIALLY FOR THOSE WITH GREATER  
EXPOSURE OR THOSE EXERTING THEMSELVES OUTDOORS. WITH MANY SCHOOLS  
GOING BACK IN SESSION, IT'S WORTH REMINDING KIDS (AND  
TEACHERS/FACULTY) TO PACE THEMSELVES AND HYDRATE APPROPRIATELY.  
 

 
   
AVIATION
 
UPDATED 0029Z.  
 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:  
 
STORMS TO THE NORTH, EAST, AND SOUTH OF THE PHOENIX OVER  
SOUTHEAST AND EASTERN AZ HAVE BEEN ISOLATED WITH NEWER DEVELOPMENT  
OVER SOUTHWEST MARICOPA COUNTY. OUTFLOW THAT HAD BEEN APPROACHING  
FROM PIMA COUNTY HAS WEAKENED. GIVEN THE LACK OF MORE ROBUST  
ACTIVITY, AND CONVECTIVE INHIBITION EVIDENT IN AIRCRAFT SOUNDING  
DATA, HAVE REMOVED THE MENTION OF VCTS FROM THE TAFS. HOWEVER,  
STORMS OVER SOUTHWEST/WEST MARICOPA COUNTY COULD PRODUCE OUTFLOW  
THAT POTENTIALLY REACH THE THE TAF SITES. AS HAS BEEN SEEN A  
NUMBER OF TIMES THIS MONSOON SEASON, LATE NIGHT SHOWER AND  
THUNDERSTORM ACTIVITY WILL BE POSSIBLE, BUT WOULD EXPECT IT TO BE  
WEAKER THAN LAST NIGHT AND MORE ISOLATED (IF IT HAPPENS AT ALL).  
APART FROM OUTFLOWS, LIGHT WEST AND NORTHWEST WINDS WILL PREVAIL  
BEFORE TRENDING TOWARD LIGHT EASTERLY LATE TONIGHT. AS FOR SKY  
COVER, EXPECT INCREASING MID AND HIGH CLOUDS AS THE NIGHT  
PROGRESSES FOLLOWED BY THINNING DURING THE DAY WEDNESDAY.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
 
KIPL: THUNDERSTORMS ARE ONGOING IN THE VICINITY OF KIPL WITH GUSTS  
OF 30-35 KTS AND BLOWING DUST DROPPING VISIBILITY BELOW 6SM.  
ANTICIPATE ERRATIC WINDS AND AT LEAST ONE DOWNPOUR REDUCING VIS TO  
BETWEEN 2SM - 4SM ALONG WITH CEILINGS TO BETWEEN FL070-090.  
ANTICIPATE SIGNIFICANT DECLINE IN STORM ACTIVITY TO BEGIN BY 02Z.  
WINDS WILL BECOME LIGHTER AS WELL WITH VARIABLE DIRECTIONS BEFORE  
SOUTHEASTERLY RESUMES OVERNIGHT. THERE IS POTENTIAL FOR ANOTHER  
ROUND OF ACTIVITY TOMORROW AFTERNOON.  
 
KBLH: EARLIER STORM ACTIVITY HAS LIKELY HELPED STABILIZE THINGS  
OVER/NEAR KBLH TO PRECLUDE NEW STORM DEVELOPMENT THE REST OF THE  
AFTERNOON AND EVENING. A ROUND OF LATE NIGHT/MORNING SHOWERS IS  
POSSIBLE BUT CONFIDENCE OF THOSE OCCURRING AT THE AIRFIELD TOO  
LOW TO REFLECT IN THE TAF. ANTICIPATE LIGHT AND VARIABLE WINDS TO  
BECOME SOUTHERLY OVERNIGHT AND CONTINUE THROUGH THE DAY WEDNESDAY.  
AS FOR SKY COVER, ANTICIPATE VARIABLE AMOUNTS OF MID AND HIGH  
CLOUDS WITH BASES AOA FL120.  
 

 
   
FIRE WEATHER
 
 
A HUMID AIRMASS WILL REMAIN IN PLACE THROUGH THE FORECAST PERIOD,  
YIELDING ELEVATED AFTERNOON RH VALUES AND GOOD OVERNIGHT RECOVERY.  
CHANCES FOR WETTING RAINS WILL CONTINUE FOR MOST AREAS ALMOST  
DAILY. WINDS FOR THE MOST PART WILL REMAIN LIGHT, WITH THE  
EXCEPTION OF THUNDERSTORM OUTFLOWS GENERATING STRONGER GUSTS. THE  
FIRE DANGER THREAT IS EXPECTED TO REMAIN LOW FOR THE FORESEEABLE  
FUTURE.  
 

 
   
PSR WATCHES/WARNINGS/ADVISORIES
 
 
AZ...FLOOD WATCH UNTIL 2 AM MST WEDNESDAY FOR AZZ530>544-546-548>551-  
553>555-559.  
 
FLOOD WATCH UNTIL MIDNIGHT MST TONIGHT FOR AZZ545-547-552-  
556>558-560>563.  
 
CA...FLOOD WATCH UNTIL 2 AM PDT WEDNESDAY FOR CAZ560>570.  
 

 
 

 
 
DISCUSSION...SAWTELLE/INIGUEZ  
AVIATION...AJ  
FIRE WEATHER...INIGUEZ  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab AZ Page
The Nexlab CA Page Main Text Page