Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 032204
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
305 PM MST SUN MAY 3 2015

.SYNOPSIS...A SERIES OF PACIFIC WEATHER DISTURBANCES IS FORECAST TO
MOVE INTO THE REGION...RESULTING IN A COOLING TREND. A LARGE AND
COLDER DISTURBANCE IS FORECAST TO MOVE INTO THE REGION LATE TONIGHT
THROUGH TUESDAY...FOR AN INCREASING CHANCE OF SHOWERS AND
THUNDERSTORMS...MAINLY ACROSS ARIZONA. CLEARING IS EXPECTED LATE
TUESDAY THROUGH THE REMAINDER OF THE WEEK AND NEXT WEEKEND...HOWEVER
WITH SEVERAL PACIFIC WEATHER SYSTEMS FORECAST TO MOVE INTO THE
WESTERN STATES NORTH OF ARIZONA THIS WEEK...BELOW NORMAL
TEMPERATURES ARE EXPECTED THE NEXT SEVEN DAYS.

&&

.DISCUSSION...

TONIGHT THROUGH TUESDAY...MINIMAL CONVECTIVE ACTIVITY WAS NOTED SO
FAR AT 2 PM MST ACROSS OUR FORECAST AREA AS UPPER LEVEL CONVERGENCE
HAS STABILIZED MOST OF SOUTHERN AZ. ALSO NOTED FROM VISIBLE
SATELLITE IMAGERY WAS THE LONG FETCH OF CLOUD STREETS EXTENDING INTO
SOUTHERN AZ FROM MEXICO/GULF OF CA. PRECIP WATER (PW) IMAGERY ALSO
SHOWED PW AMOUNTS HAD INCREASED ACROSS THE ENTIRE GULF OF CA
SUGGESTING CONTINUED MOISTURE ADVECTION THE REMAINDER OF TODAY AND
TONIGHT AHEAD OF MONDAYS ANTICIPATED TROF.

FOR MONDAY AND TUESDAY A MAJOR COOL PACIFIC TROF IS STILL ON TRACK
TO MOVE FORECAST TO MOVE INTO SOUTHERN CA TONIGHT THEN INTO AZ
MONDAY MORNING THROUGH TUESDAY MORNING. THIS IS A MUCH COLDER TROF
WITH WITH SOMEWHAT STRONG UPPER LEVEL DYNAMICS...AND...WITH
INCREASED BOUNDARY LAYER MOISTURE WILL LEAD TO A GOOD CHANCE OF
SHOWERS AND THUNDERSTORMS AREA-WIDE. SINCE IT WILL BE A SLOW
EASTWARD MOVING TROF...THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL
CONTINUE INTO EARLY TUESDAY.

WEDNESDAY...PARTLY CLOUDY SKIES ARE EXPECTED WITH NO PRECIP AS A
MINOR SHORTWAVE RIDGE MOVES QUICKLY THROUGH THE REGION.

THURSDAY THROUGH SATURDAY...ANOTHER COOL TROF IS FORECAST TO MOVE
INTO THE WESTERN REGION MAINLY NORTH OF OUR FORECAST AREA. PRECIP
CHANCES SHOULD MOSTLY BE CONFINED TO OUR SOUTHEAST CA JOSHUA TREE
ZONE 30. HOWEVER...STRONG 500-300 MB HEIGHT FALLS OVER THE MOHAVE
DESERT OF CA FRIDAY SUGGESTS VERY STRONG GUSTY WEST WINDS ACROSS
MUCH OF SOUTHEAST CA AND THE COLORADO RIVER VALLEY.


&&

.AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND
KSDL...

MORE STABLE ATMOSPHERIC SET-UP TODAY WILL PROVIDE A BRIEF BREAK IN
BETWEEN THE PRECIP ACTIVITY OVER THE SOUTH-CENTRAL AZ DESERTS. FEW-
SCT CU FIELDS AOA 10-12KFT WILL LINGER UNTIL AFTER SUNSET THEN
GRADUALLY CLEAR OFF. AFTN WINDS TO WORK THEIR WAY INTO SW-W HEADINGS
WITH SPEEDS 10-15KTS AT THEIR PEAK. MOISTURE SURGE FROM THE
SOUTHWEST WILL BE ACCOMPANIED BY ELEVATED WINDS JUST ABOVE THE SFC
THAT MAY CREATE PERIODS OF LLWS CONDITIONS. UNCERTAINTY REMAINS IF
SFC WINDS WILL CALM OUT ENOUGH FOR IT TO BE A SIGNIFICANT IMPACT IN
TERMS OF SPEED DIFFERENTIAL...25 TO 30 KTS OR SO. PRECIP ACTIVITY
WILL BE POSSIBLE EARLY IN THE AM...WITH AT LEAST VCSH COVERAGE FOR
THE PHX TERMINALS BY 12Z. CIGS TO GRADUALLY LOWER DOWN TOWARDS 4-
6KFT INTO MONDAY AM.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND
KBLH... FEW TO SCT CUMULUS FIELDS OVER THE TERMINALS THROUGH SUNSET
THEN MID LEVEL CLOUDS TO GIVE WAY TO PASSING HIGH LEVEL CLOUDS GNLY
AOA 20KFT. ELEVATED S-SE WINDS TO PERSIST OVERNIGHT ALONG THE CO
RIVER VALLEY AND KBLH WHILE WESTERLY WINDS FOR KIPL WILL CONTINUE
THROUGH EARLY EVENING. ANY PRECIP ACTIVITY OVERNIGHT AND INTO MONDAY
SHOULD STAY EAST OF THE TERMINALS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER... WEDNESDAY THROUGH SUNDAY... DRY WEATHER...AND
SLIGHTLY WARMER TEMPERATURES TO RETURN WEDNESDAY AS WEAK HIGH
PRESSURE PASSES OVER THE REGION. GUSTY WINDS AND COOLER TEMPERATURES
TO PREVAIL ACROSS THE REGION FROM THURSDAY ONWARD INTO SATURDAY AS
ANOTHER PACIFIC STORM SYSTEM MOVES ACROSS THE GREAT BASIN. FIRE
DANGER LEVELS WILL LIKELY BE ELEVATED DURING THIS PERIOD AS
AFTERNOON HUMIDITIES FALL INTO THE TEENS. SLIGHTLY WARMER
TEMPERATURES AND LESS WIND CAN BE EXPECTED ON SATURDAY AS THE
AFOREMENTIONED PACIFIC STORM SYSTEM BEGINS TO MOVE OFF TO THE EAST.

&&

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

$$

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

DISCUSSION...VASQUEZ AVIATION...NOLTE/PERCHA FIRE WEATHER...PERCHA



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