Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 012225
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
325 PM MST TUE SEP 1 2015

.UPDATE...TO AVIATION DISCUSSION...

&&

.SYNOPSIS...
LOW END CHANCES FOR SHOWERS AND THUNDERSTORMS CONTINUE TODAY FROM
PHOENIX EAST...THEN INCREASE FURTHER FOR WEDNESDAY AND THURSDAY AS
LOW PRESSURE OFF THE CALIFORNIA MOVES INTO THE REGION. A RETURN OF
DRIER AIR INTO THE REGION WILL REDUCE CHANCES FOR SHOWERS AND
THUNDERSTORMS FROM FRIDAY ONWARD INTO THE UPCOMING WEEKEND.

&&

.DISCUSSION...
DEW POINTS CONTINUE TO RUN HIGHER AND TEMPERATURES COOLER COMPARED TO
YESTERDAY CWA-WIDE DUE TO A COMBINATION OF GULF SURGE AND PREVIOUS
THUNDERSTORM ACTIVITY. AFTERNOON CONVECTION IS MUTED AT THIS
TIME...WILL HAVE TO MONITOR FOR FURTHER DEVELOPMENT BUT OVERALL
SHOULD BE A QUIETER DAY. WILL MAINTAIN LOW END POPS FROM ABOUT
PHOENIX EAST FOR POTENTIAL OF A STRAY SHOWER OR STORM BUT FAR MORE
LIKELY THE RAIN/STORMS DON/T MATERIALIZE.

GOING FORWARD THE NEXT FEW DAYS...PRIMARY MOISTURE AXIS AS DEPICTED
BY SUB-700 HPA MIXING RATIOS WILL REMAIN ORIENTED NORTH-SOUTH JUST TO
THE WEST OF THE AZ-NM BORDER. MOISTURE LEVELS WILL INCREASE TOMORROW
AND AGAIN THURSDAY AS A MID-LEVEL TROUGH PROGRESSES INTO THE WESTERN
US...INCREASING THE SOUTHERLY FLOW AND INGESTING A BIT OF MID-LEVEL
MOISTURE FROM TROPICAL SYSTEM 14-E. THAT SYSTEM MAY BE NAMED
TONIGHT/TOMORROW BY NHC BUT THE LOW LEVEL CIRCULATION WILL REMAIN
SOUTH OF 25N BY CURRENT NHC FORECAST...AT WHICH POINT IT/LL GRADUALLY
DECAY. THE MID-LEVEL CIRCULATION WILL LIKELY SHEAR OUT IN THE
APPROACHING TROUGH AND SOME OF THAT ENERGY...ALONG WITH THE
INCREASING BOUNDARY LAYER MOISTURE...IS EXPECTED TO RESULT IN ANOTHER
UPSWING IN THUNDERSTORM ACTIVITY FOR MARICOPA COUNTY AND AREAS EAST.

THUNDERSTORM ACTIVITY WILL LIKELY PEAK WED-THU THEN TREND DOWN A BIT
FRIDAY AND FROM SATURDAY INTO EARLY NEXT WEEK PLATEAU AT A LOW GRADE
LEVEL. WE/VE BEEN TALKING ABOUT A DRYING TREND FOR A WHILE NOW AND AT
THIS POINT IT MAY BE TIME TO ACCEPT IT ISN/T RIGHT AROUND THE CORNER.
WHILE GLOBAL ENSEMBLES DUE SUGGEST PWATS DROPPING BY EARLY NEXT
WEEK...DETERMINISTIC GFS/EC RUNS KEEP THE MONSOON MOISTURE PLUME
ALONG THE AZ/NM BORDER IN PLACE THROUGH TUE/WED AND THE BROADER
TROUGH PATTERN OVER THE WEST COAST REMAINS. NOT MUCH REASON TO EXPECT
THIS ESTABLISHED PATTERN TO CHANGE AT THIS TIME THUS INCREASED POPS
FOR MARICOPA EAST /WHICH WILL BE ON THE FRINGE OF THE MOISTURE
PLUME/.

FOR SW AZ AND INTO SE CA...IT/LL LIKELY REMAIN WARM...HUMID...AND
DRY. AND WITH A STAGNANT WEATHER PATTERN...NO REAL SIGNIFICANT
TEMPERATURE SWINGS EXPECTED.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
AMPLE MONSOON MOISTURE REMAINS OVER THE REGION HOWEVER SLIGHTLY
COOLER CONDITIONS...COURTESY OF LAST NIGHT`S STORMS...SHOULD HELP
HOLD BACK MOST OF THE POTENTIAL FOR STORMS TODAY. COULD SEE SOME
DISTANT STORMS WELL EAST AND SOUTH OF PHOENIX WITH ONLY THE MOST
REMOTE CHANCES OF ANYTHING MAKING IT INTO THE METRO LIKELY AFTER
PEAK TRAFFIC PERIODS. CANNOT RULE OUT SOME SHOWER ACTIVITY
OVERNIGHT...BUT CONFIDENCE IN INCLUDING IN ALL THE PHX METRO TAFS IS
LOW ATTM. WINDS WILL EVENTUALLY SWING SOUTHWEST TO WESTERLY INTO THE
AFTN...OTHERWISE REMAIN LIGHT ENOUGH TO PRODUCE PERIODS OF VRB. MID
AND HIGH CLOUDS TO CONTINUE STREAMING IN FROM THE SOUTH...VARYING
FROM SCT TO OVC IN NATURE.

SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
SCT TO BKN MID AND HIGH CLOUDS WILL CONTINUE TO STREAM IN FROM THE
SOUTHWEST THROUGH THE EVENING...GNLY REMAINING ABOVE 10KFT AGL.
MAINLY SOUTHERLY WINDS TO PERSIST ACROSS THE AREA...OTHERWISE WINDS
WILL BE LIGHT ENOUGH TO PRODUCE PERIODS OF VRB.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
MOISTURE WILL INCREASE ACROSS THE AREA BY THE MIDDLE OF THE WEEK
RESULTING IN ELEVATED STORM CHANCES FROM PHOENIX EASTWARD ON
THURSDAY. MOISTURE VALUES WILL WANE A BIT INTO THE WEEKEND ALTHOUGH
DAILY STORM CHANCES WILL REMAIN PRESENT THROUGH EARLY NEXT WEEK.
MINIMUM RH VALUES WILL FALL BELOW 15 PERCENT THURSDAY ACROSS
SOUTHEAST CALIFORNIA WITH VALUES ABOVE 15 PERCENT EXPECTED EAST OF
THE LOWER COLORADO RIVER. FOR FRIDAY INTO THE WEEKEND...LATEST
GUIDANCE MORE INSISTENT UPON A RETURN TO DEEPER MOISTURE...HIGHER
HUMIDITY AND BETTER RAIN CHANCES...PARTICULARLY ACROSS SOUTH CENTRAL
ARIZONA.

&&

.SPOTTER INFORMATION STATEMENT...
SPOTTERS ARE ENCOURAGED TO REPORT CONDITIONS ACCORDING TO STANDARD
OPERATING PROCEDURES.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...INIGUEZ
AVIATION...NOLTE
FIRE WEATHER...MP


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