Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 180510
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1010 PM MST WED DEC 17 2014

.SYNOPSIS...
THE LAST TWO IN A SERIES OF FAST MOVING WEATHER SYSTEMS MOVING
THROUGH THE WESTERN STATES WILL KEEP PRECIPITATION CHANCES ELEVATED
THROUGH THURSDAY. THE BEST CHANCES FOR SHOWERS ARE EXPECTED THIS
EVENING...AND AGAIN DURING THE DAY ON THURSDAY...MAINLY ACROSS
SOUTHWEST AND SOUTH-CENTRAL ARIZONA. DRY WEATHER IS EXPECTED TO
RETURN BY THE END OF THE WEEK...WITH A GRADUAL WARMING TREND
ANTICIPATED FROM THE WEEKEND ONWARD INTO THE MIDDLE OF NEXT
WEEK...BEFORE A POSSIBLE CHANGE TO MUCH COLDER WEATHER BY THE END OF
NEXT WEEK.

&&

.DISCUSSION...
LIGHT RAIN SHOWER ACTIVITY CONTINUES OVER PORTIONS OF PINAL COUNTY
AND SOUTHEAST AZ THIS EVENING AS THE NEXT IN THE SERIES OF
SHORTWAVES MOVES INTO THE AREA. CONSIDERABLE CLOUD COVER KEPT
TEMPERATURES ON THE COOLER SIDE TODAY...RESULTING IN HIGHS IN THE
UPPER 50S TO LOW 60S ACROSS MANY OF THE LOWER DESERT LOCALES.
PHOENIX SKY HARBOR ONLY PEAKED AT 61F. RAINFALL AMOUNTS ACROSS THE
AREA WERE GENERALLY LIGHT FROM THE PASSING SHOWERS...SAVE FOR ONE
STRONGER THUNDERSHOWER THAT TREKKED ALONG INTERSTATE 10 FROM BLYTHE
TOWARDS QUARTZSITE IN THE LATE AFTERNOON. SKIES WERE QUICK TO CLEAR
OUT ALONG AND WEST OF THE CO RIVER VALLEY...WITH INSTABILITY CU AND
MORE ORGANIZED SHOWER ACTIVITY DROPPING A QUICK THREE TENTHS OF AN
INCH AT THE BLYTHE AIRPORT.

FOR THE REST OF TONIGHT INTO TOMORROW AM...LATEST HI-RES AND 00Z
GFS/NAM GUIDANCE TIME OUR NEXT POTENTIAL ROUND OF SHOWER ACTIVITY
DEVELOPING INTO SOUTH-CENTRAL AZ DURING THE MORNING HOURS AND
QUICKLY WRAPPING AROUND 19/00Z AS THE SHORTWAVE AXIS CLEARS TO OUR
EAST. AHEAD OF THE APPROACHING SHORTWAVE...AREA DEWPOINTS REMAIN
ELEVATED AND TEMP/DEWPOINT SPREAD ACROSS SOME AREAS ARE SEPARATED BY
ONLY A FEW DEGREES. WITH A STILL MOIST BOUNDARY LAYER AND SOME AREAS
WITH PONDED WATER LINGERING FROM TODAY`S RAIN...COULD SEE FOG
DEVELOPMENT OVERNIGHT. HOWEVER...WITH ANOTHER AREA OF MID TO HIGH
LEVEL CLOUDS MOVING IN FROM THE SOUTHWEST DEVELOPMENT COULD BE
LIMITED. LEFT MENTION IN THE OVERNIGHT WEATHER GRIDS...WITH AREAS OF
FOG POSSIBLE ACROSS THE I-8 CORRIDOR NEAR EL CENTRO/IMPERIAL AND
TOWARDS YUMA AND PATCHY FOG MENTIONING BACK INTO THE SOUTH-CENTRAL
AZ DESERTS. OTHER GRID UPDATES INCLUDED HOURLY GRID UPDATES FOR
TEMPERATURES AND DEWPOINTS...AS THEY WERE RUNNING HIGHER THAN
FORECAST MOST LIKELY DUE TO THE INCREASING CLOUD COVER.

&&

.PREVIOUS DISCUSSION /ISSUED AT 115 PM MST/1215 PM PST/...
TONIGHT THROUGH THURSDAY...

THURSDAY WILL LIKELY SEE ONE LAST SHOT OF LIGHT RAINFALL AS THE
FINAL SHORTWAVE IN THE SERIES...WHICH EARLIER HAD BEEN EXPECTED TO
TRACK WELL TO OUR SOUTH ACROSS MEXICO...MOVES ACROSS SOUTH-CENTRAL
ARIZONA. RAINFALL AMOUNTS WITH THIS SHORTWAVE ARE EXPECTED TO REMAIN
QUITE LIGHT...RANGING FROM A FEW HUNDREDTHS OF AN INCH ACROSS THE
PHOENIX AREA UP TO AROUND 0.10 OF AN INCH OVER THE HIGHER TERRAIN
NORTH AND EAST OF PHOENIX. THE CLOUDS AND RAINFALL WILL LIKELY ONCE
AGAIN KEEP HIGH TEMPERATURES SLIGHTLY BELOW NORMAL ON
THURSDAY...MAINLY IN THE LOW TO MID 60S ACROSS THE LOWER DESERTS.

FRIDAY THROUGH WEDNESDAY...
DRY WEATHER IS FORECAST TO RETURN BY FRIDAY...THEN CONTINUE INTO AT
LEAST THE MIDDLE PART OF NEXT WEEK AS RIDGING BUILDS BACK EASTWARD
OVER THE REGION. ALTHOUGH LATEST MODEL RUNS CONTINUE TO BRING
ANOTHER WEAK SHORTWAVE ACROSS OUR CWA FRIDAY NIGHT AND
SATURDAY...THEY CONTINUE TO KEEP IT COMPLETELY DRY...WITH JUST AN
INCREASE IN CLOUDINESS ASSOCIATED WITH IT. AS FAR AS TEMPERATURES
ARE CONCERNED...AFTER HIGHS IN THE LOW TO MID 60S FROM FRIDAY INTO
SUNDAY...THEY ARE EXPECTED TO RISE INTO THE LOW TO MID 70S BY
TUESDAY AND WEDNESDAY OF NEXT WEEK AS HIGH PRESSURE RIDGING ALOFT
STRENGTHENS OVER THE DESERT SOUTHWEST. AS FAR AS THE FORECAST FOR
THE END OF NEXT WEEK...EVEN THOUGH IT IS STILL WELL OUT IN THE
EXTENDED PERIOD...MODEL CONSENSUS IS BUILDING TOWARD THE IDEA OF A
CHANGE TO MUCH COLDER WEATHER...AS THE EURO AND GFS NOW BOTH DIG A
VERY DEEP...AND COLD LOW-WAVE TROF SOUTHWARD INTO THE WESTERN STATES
DURING THIS PERIOD.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
WIDESPREAD SHOWER ACTIVITY HAS CLEARED TO THE EAST-SOUTHEAST OF THE
PHOENIX METRO LEAVING POCKETS OF LOW TO MID LEVEL CIGS GNLY AOA
5KFT. A STRAY SHOWER COULD SKIRT THROUGH THE AREA TONIGHT...BUT THE
NEXT ROUND OF ORGANIZED...ALBEIT LIGHT...SHOWER ACTIVITY SHOULD HOLD
OFF UNTIL THURSDAY MID-MORNING. OVERNIGHT CONCERN PERTAINS TO
AIRFIELD VSBYS DUE TO ELEVATED LOW LEVEL MOISTURE AND AIR POLLUTION
GENERATING HAZE AND SLANT VSBY ISSUES. THERE IS A REMOTE CHANCE OF
SOME FOG DEVELOPMENT...POSSIBLE VICINITY...FOR KSDL AND KIWA TOWARDS
THE MORNING. INCREASING MID TO HIGH LEVEL CLOUD COVER FROM THE
SOUTHWEST MIGHT PREVENT SIGNIFICANT DEVELOPMENT...SO DID NOT INCLUDE
MENTION OTHER THAN VCFG IN THE KIWA TAF. WINDS WILL GENERALLY BE
LIGHT UNDER 6KTS OR LESS.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA...INCLUDING KIPL AND
KBLH...
ADDITIONAL LIGHT AND ISOLATED SHOWER ACTIVITY MAY DEVELOP FROM THE
WEST...BUT BE VERY LIGHT IN NATURE...THROUGH THE NIGHT. EXPECT AREAS
OF HAZE/MIST/FOG TO DEVELOP OVERNIGHT IMPACTING AIRFIELD VSBYS AND
CIGS...ESPECIALLY FOR KIPL THROUGH LATE MORNING. EXPECTING CLEARING
FROM THE WEST THURSDAY LATE MORNING...AS THE LAST CHANCE FOR SHOWERS
ENDS. NO WIND ISSUES NEXT 24 HOURS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
THE WET WEATHER PATTERN EXPERIENCED DURING THE MIDDLE OF THE WEEK
WILL CHANGE TO A WARMER AND DRIER PATTERN AS DRIER NORTHWEST FLOW
ALOFT STARTS TO BUILD INTO THE AREA FROM THE WEST STARTING ON
FRIDAY. A WEAK WEATHER DISTURBANCE PASSES ACROSS THE AREA FROM THE
NORTHWEST SATURDAY BUT BRINGS LITTLE IF ANY CHANCE FOR RAIN. SUNDAY
INTO THE MIDDLE OF NEXT WEEK A LARGE AREA OF HIGH PRESSURE BUILDS
INTO THE DESERT SOUTHWEST LEADING TO GRADUALLY DRIER AND WARMER
CONDITIONS. EXPECT HIGH TEMPERATURES NEAR NORMAL THROUGH SATURDAY...
WITH WARMING STARTING ON SUNDAY AND CONTINUING THROUGH TUESDAY. BY
NEXT TUESDAY...HIGH TEMPERATURES WILL REACH INTO THE LOW TO MIDDLE
70S OVER THE WARMER LOWER DESERTS. MINIMUM HUMIDITY VALUES WILL STAY
ELEVATED THROUGH THE 5 DAY PERIOD...BUT WILL GRADUALLY LOWER DAY TO
DAY AS BOTH DRIER AIR WORKS IN FROM THE WEST AND TEMPERATURES CLIMB.
DESPITE THE DRYING MINIMUM RH VALUES WILL RANGE MOSTLY BETWEEN 20
AND 30 PERCENT NEXT MONDAY AND TUESDAY. WINDS WILL NOT BE AN ISSUE
DURING THE PERIOD...REMAINING ON THE LIGHT SIDE AND FOLLOWING NORMAL
DIURNAL PATTERNS EACH DAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...NOLTE
PREVIOUS DISCUSSION...PERCHA
AVIATION...NOLTE
FIRE WEATHER...CB







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