Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 211114
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
413 AM MST TUE OCT 21 2014

.UPDATE...AVIATION AND FIRE WEATHER DISCUSSIONS.

&&

.SYNOPSIS...
GRADUAL DRYING WILL OCCUR THIS WEEK...BUT THERE WILL BE ONE LAST DAY
OF SLIGHT CHANCES FOR SHOWERS AND THUNDERSTORMS ACROSS THE MOUNTAINS
NORTH AND EAST OF PHOENIX TODAY. SOME WARMING IS EXPECTED BY MID
WEEK...LASTING THROUGH SATURDAY WITH HIGHS 5-10 DEGREES ABOVE
NORMAL. A COOL DOWN IS EXPECTED TO TAKE PLACE ON SUNDAY INTO EARLY
NEXT WEEK BRINGING TEMPERATURES BACK TO NEAR SEASONAL NORMALS.

&&

.DISCUSSION...
THE UPPER LEVEL LOW THAT HAS BROUGHT DAYTIME SHOWER AND THUNDERSTORM
ACTIVITY THE PAST TWO DAYS IS NOW OVER SOUTHWEST NEW MEXICO...WHILE
ANOTHER UPPER LEVEL SYSTEM...MAINLY FOCUSED ACROSS THE GREAT
BASIN...WILL DRAG A WEAK TROUGH AXIS THROUGH ARIZONA TODAY.
LINGERING LOW LEVEL MOISTURE AND SUFFICIENT DAYTIME HEATING WILL
AGAIN ALLOW FOR SOME ISOLATED SHOWERS AND THUNDERSTORMS ACROSS
EASTERN ARIZONA THIS AFTERNOON WITH SLIGHT CHANCE POPS OVER FAR
EASTERN GILA COUNTY. DRY CONDITIONS WILL REMAIN ACROSS THE LOWER
DESERTS EVEN THOUGH PRECIPITABLE WATER VALUES WILL REMAIN NEAR ONE
INCH AS WARM MID LEVEL TEMPERATURES AND THE LACK OF ANY FORCING
MECHANISM INHIBITS ANY SHOWER OR THUNDERSTORM DEVELOPMENT.

HIGH TEMPERATURES THIS AFTERNOON WILL BE SIMILAR TO MONDAY...BUT A
WARM UP IS EXPECTED STARTING WEDNESDAY. THE PACIFIC RIDGE IS
FORECAST TO BUILD NORTHEASTWARD INTO THE DESERT SOUTHWEST OVER THE
NEXT FEW DAYS ALLOWING 500MB HEIGHTS TO RISE TO AROUND 588DM. MODEL
GUIDANCE OVER THE PAST COUPLE DAYS HAS TRENDED WARMER FOR THE
WEDNESDAY THROUGH SATURDAY TIMEFRAME AND HAVE ADJUSTED OUR HIGHS
UPWARD SLIGHTLY TO ACCOMMODATE. THE WARMEST DAY SHOULD END UP BEING
FRIDAY AS THE RIDGE AXIS PASSES OVER ARIZONA LATE THURSDAY INTO
EARLY FRIDAY. FOR FRIDAY...READINGS IN THE MIDDLE 90S SHOULD BE
COMMON ACROSS THE LOWER DESERTS AND A FORECAST HIGH OF 95 AT PHOENIX
IS JUST ONE DEGREE SHY OF THE RECORD FOR THE DAY.

A LESS CLEAR PICTURE IS SHOWN FOR THIS WEEKEND INTO EARLY NEXT WEEK
AS SIGNIFICANT MODEL DIFFERENCES ARE SHOWN FOR SUNDAY AND MONDAY.
THE EUROPEAN AND THE CANADIAN MODELS ARE NOW SHOWING A FAIRLY STRONG
PV ANOMALY BREAKING OFF FROM A NORTH PACIFIC LOW AND SLIDING
SOUTHEASTWARD INTO OR NEAR THE DESERT SOUTHWEST SOMETIME SUNDAY INTO
MONDAY. THE GFS REMAINS MUCH WEAKER AND FURTHER NORTH WITH THIS
FEATURE. EITHER WAY...LITTLE TO NO MOISTURE IS CURRENTLY SHOWN TO
ACCOMPANY THIS POTENTIAL SHORTWAVE TROUGH...BUT WILL HAVE TO MONITOR
FOR ANY CHANGES OVER FUTURE MODEL RUNS. LONG RANGE MODELS DO AGREE
THAT AN OVERALL TROUGHING PATTERN WILL TAKE OVER STARTING SUNDAY
ALLOWING FOR A SIGNIFICANT COOL DOWN...PROBABLY BACK TO NEAR NORMAL
OR HIGHS IN THE LOWER TO MIDDLE 80S ACROSS THE LOWER DESERTS.

&&

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

THROUGH 03Z WED...MOSTLY CLEAR SKIES. LIGHT WIND UNDER 8 KNOTS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
A STRONG HIGH PRESSURE WILL BUILD OVER ARIZONA AND REMAIN IN PLACE
THROUGH FRIDAY...THEN GRADUALLY WEAKEN THIS WEEKEND AS A FEW WEATHER
SYSTEMS MOVE INTO THE WESTERN STATES NORTH OF ARIZONA. EXCEPT FOR
CONSIDERABLE HIGH CLOUDS THIS WEEKEND...DRY WEATHER WITH ABOVE
NORMAL AFTERNOON TEMPERATURES WILL CONTINUE. MINIMUM RELATIVE
HUMIDITY WILL GENERALLY RANGE FROM 17 TO 20 PERCENT...EXCEPT NEAR 35
PERCENT IN THE SOUTHERN GILA COUNTY. LIGHT WIND IS GENERALLY
EXPECTED...HOWEVER GUSTY SOUTH WINDS 10 TO 20 MPH WILL LIKELY
DEVELOP ALONG THE COLORADO RIVER VALLEY SATURDAY AFTERNOON. MOSTLY
GOOD RECOVERY IS EXPECTED AT NIGHT.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...KUHLMAN
AVIATION...VASQUEZ
FIRE WEATHER...VASQUEZ














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