Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 300318
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
815 PM MST FRI MAY 29 2015

.SYNOPSIS...
HOT AND DRY WEATHER WILL PERSIST OVER SOUTHEAST CALIFORNIA AND
SOUTHERN ARIZONA THIS WEEKEND WITH AFTERNOON HIGHS RANGING FROM
AROUND 102 TO 108 DEGREES FOR LOWER ELEVATION POPULATION CENTERS.
TEMPERATURES WILL COOL SOMEWHAT HEADING INTO THE MIDDLE OF NEXT
WEEK...COMING CLOSER TO THE SEASONAL NORMALS.

&&

.DISCUSSION...
MODERATE AMPLITUDE LONGWAVE RIDGING HAS BUILT OVER THE SWRN CONUS
DURING THE PAST 24 HOURS WITH 00Z REGIONAL SOUNDING DATA SAMPLING 2
TO 3DM H5 HEIGHT RISES. IN ADDITION...THERMAL STRUCTURE OF THE H8-H7
LAYER HAS INCREASED 1F-2F WITH DEEP MIXING THROUGH 600MB YIELDING
THE WARMEST DAY OF THE YEAR SO FAR. ALL EARLY 00Z MODEL GUIDANCE
STILL SHOWS A CONTINUATION OF THIS TREND SUGGESTING LOWER ELEVATION
HIGH TEMPS IN A 102F-106F RANGE TOMORROW. IN THE SHORT TERM...MINOR
ADJUSTMENTS TO HOURLY TEMPERATURES WERE MADE AS READINGS WERE
FALLING SLOWER THAN FORECAST GIVEN THE WARM AFTERNOON.
OTHERWISE...FEW OTHER CHANGES WERE NECESSARY IN THE EVENING UPDATE.

&&

.PREVIOUS DISCUSSION...
/235 PM MST FRI MAY 29 2015/
THE BIG STORY FOR THE NEXT SEVERAL DAYS IS THE INEVITABLE RETURN OF THE
TRIPLE DIGITS ACROSS THE MAJORITY OF THE FORECAST AREA. EXCELLENT
MODEL AGREEMENT NOTED AMONG TODAY`S 00Z DETERMINISTIC MODELS AND
PROBABILISTIC GUIDANCE...WITH ALL SIGNS POINTING TO STRENGTHENING
UPPER RIDGING AND STEADILY INCREASING 925-700MB TEMPERATURES. THIS
WILL RESULT IN THE WARMEST TEMPERATURES OF THE YEAR /SO FAR/ THROUGH
THE WEEKEND...WITH HIGHS PEAKING ON SUNDAY IN THE 105-108 RANGE.
BLENDED BIAS CORRECTED GUIDANCE ALL WITHIN A DEGREE OR TWO OF THE
INHERITED FORECAST AND NO SIGNIFICANT CHANGES APPEAR NECESSARY WITH
THIS MORNING`S FORECAST. WHILE RECORD HEAT IS NOT FORECAST ACROSS THE
LOWER DESERTS...PHOENIX WILL CERTAINLY COME CLOSE ON SUNDAY /SEE
CLIMATE SECTION BELOW/.

ALSO WORTH NOTING THIS WEEKEND...DETERMINISTIC MODELS INDICATE A
SUBTLE INCREASE IN BL MOISTURE /6-7 G/KG BL MIXING RATIOS/ ACROSS
EASTERN ARIZONA DURING THE DAY SUNDAY. GFS/NAM INDICATING AT LEAST A
FEW HUNDRED J/KG OF MLCAPE ACROSS THE HIGHER TERRAIN LOCATIONS ALONG
THE AZ/NM BORDER AND SOME OF THE EXTENDED HI-RES GUIDANCE IS HINTING
AT A FEW SHOWERS/TSTORMS WELL EAST OF PHOENIX SUNDAY AFTERNOON. GOING
TO INSERT CLIMO-LIKE POPS ACROSS SOUTHERN GILA COUNTY ALTHOUGH AT
THIS POINT THE AREAL COVERAGE OF ANY SHOWERS/STORMS APPEARS QUITE
LOW. THIS MOISTURE CREEP WILL BE VERY SHORT LIVED AS THE RIDGE AXIS
SHIFTS EASTWARD ON MONDAY...EFFECTIVELY PUTTING AN END TO ANY PRECIP
CHANCES THROUGH THE END OF NEXT WEEK.

AS THE RIDGE MOVES EAST...LONGWAVE TROUGHING IS EXPECTED TO DEVELOP
ACROSS THE WESTERN CONUS NEXT WEEK AS A RATHER DEEP LOW MOVES
THROUGH THE PAC NW. NOT EXPECTING ANY DIRECT IMPACTS FROM THIS LOW
BUT IT WILL SERVE TO KNOCK TEMPERATURES BACK A FEW DEGREES BY THE
MIDDLE/END OF THE WEEK. HIGHS /WHILE STILL WARM COMPARED TO WHAT
WE`VE SEEN LATELY/...WILL BE ON PAR WITH CLIMATOLOGICAL NORMALS FOR
EARLY JUNE. CONSENSUS GUIDANCE SUGGESTS WIDESPREAD MID/UPPER 90S FROM
WEDNESDAY THROUGH FRIDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...AND
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND
KBLH...

NO MAJOR AVIATION IMPACTS THROUGH SATURDAY NIGHT AS A NEAR
PERSISTENCE FORECAST WILL HOLD. ONLY BRIEF PERIODS OF HIGH CIRRUS
AND AFTERNOON HIGH BASED CU OVER THE MOUNTAINS OF NORTHERN AND
EASTERN ARIZONA WILL BE EXPERIENCED. WINDS SHIFT TIMING SHOULD BE
SIMILAR TO THE PAST COUPLE DAYS...WITH ONCE AGAIN EXTENDED PERIODS
OF LIGHT AND VARIABLE WINDS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
A TROUGH OF LOW PRESSURE SLOWLY MOVES THROUGH THE WESTERN STATES
NEXT WEEK LEADING TO A GRADUAL COOLING TREND AND OCCASIONAL ENHANCED
BREEZINESS...FAVORING SOUTHWESTERLY DIRECTIONS. MINIMUM HUMIDITIES
WILL GENERALLY REMAIN BELOW 10 PERCENT ON THE LOWER ELEVATIONS AND
BELOW 20 PERCENT ON THE HIGHER TERRAIN. OVERNIGHT RECOVERY WILL BE
FAIR.


&&

.CLIMATE...
HIGH TEMPERATURE FORECAST...RECORDS...AND NORMALS FOR PHOENIX AND
YUMA THROUGH THE WEEKEND...

PHOENIX    FORECAST  RECORD        NORMAL
-------    --------  ------        ------
SAT          106     114 (1910)      99
SUN          107     109 (2012)     100
MON          106     111 (2012)     100

YUMA      FORECAST   RECORD        NORMAL
----      --------   ------        ------
SAT         104      120 (1910)     100
SUN         104      113 (2012)     100
MON         104      114 (2012)     100

&&

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

&&

$$

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

DISCUSSION...MO/LEINS
AVIATION...MO
FIRE WEATHER...AJ
CLIMATE...MO/LEINS


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