Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 032020
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
120 PM MST TUE MAR 3 2015

.SYNOPSIS...
LOW PRESSURE...THAT WILL BE MOVING SLOWLY SOUTHWARD ACROSS THE
REGION...WILL KEEP THE WEATHER RATHER UNSETTLED AND COOL THROUGH
WEDNESDAY. A SLIGHT CHANCE OF SHOWERS...AND EVEN A FEW THUNDERSTORMS
CAN BE EXPECTED OVER SOUTH CENTRAL ARIZONA THROUGH TUESDAY EVENING.
A RETURN TO ABOVE NORMAL TEMPERATURES IS LIKELY BY THURSDAY...INTO
THE WEEKEND AS HIGH PRESSURE SYSTEM BUILDS OVER THE DESERT
SOUTHWEST.

&&

.DISCUSSION...
UPPER LEVEL LOW PRESSURE TROF OVER THE DESERT SOUTHWEST...EXTENDING
SOUTHWESTWARD TO A POSITION JUST OFF THE CENTRAL BAJA CA
COAST...CONTINUED TO PUSH SLOWLY EAST-SOUTHEAST THIS AFTERNOON WITH
THE TROF AXIS STARTING TO PUSH INTO FAR WESTERN ARIZONA. LINGERING
BOUNDARY LAYER MOISTURE...WITH SURFACE DEWPOINTS ACROSS THE CENTRAL
DESERTS IN THE 40S...COMBINED WITH COOL AIR ALOFT TO ALLOW FOR
SIGNIFICANT CUMULUS DEVELOPMENT OVER THE LOWER DESERTS EARLY THIS
AFTERNOON. DYNAMICS WILL BE RATHER WEAK BUT THERE WILL CERTAINLY BE
A SLIGHT CHANCE FOR INSTABILITY SHOWERS OR EVEN A WEAK THUNDERSTORM
FOR THE REST OF THE AFTERNOON AND INTO THE EVENING HOURS FOR MOST
AREAS TO THE EAST OF THE LOWER COLORADO RIVER VALLEY. IN
FACT...RADAR AT 1 PM SHOWED ISOLATED SHOWERS MOVING ACROSS THE
CENTRAL DESERTS...AND ONE PUNY SHOWER ACTALLY PRODUCED BRIEF HEAVY
RAIN AT SKY HARBOR AIRPORT.

BY WEDNESDAY MORNING THE TROF AXIS IS FORECAST TO PUSH EAST OF THE
GREATER PHOENIX AREA ALLOWING FOR A DRIER AND MORE SUBSIDENT
NLY/NWLY FLOW ALOFT TO OVERSPREAD THE CENTRAL DESERTS AND CONFINE
ANY THREAT FOR SHOWERS OR STORMS TO THE HIGHER TERRAIN AREAS EAST OF
PHOENIX. WITH BOUNDARY LAYER MOISTURE REMAINING ELEVATED WEDNESDAY
MORNING...AND SIGNIFICANT CLEARING EXPECTED BY SUNRISE...THERE WILL
AGAIN BE THE POTENTIAL FOR FOG DEVELOPMENT. WE EXPECT LESS AREAL
COVERAGE OF THE FOG AND IT SHOULD NOT BE AS DENSE AS WHAT OCCURRED
THIS MORNING...BUT WE WILL MENTION PATCHY FOG FOR WED MORNING FROM
MARICOPA COUNTY EASTWARD. BY AFTERNOON WED WE SHOULD SOME FAIR
WEATHER CU OVER THE CENTRAL DESERTS...WITH SKIES MOSTLY SUNNY FROM
PHOENIX WESTWARD. WE WILL CALL FOR A SLIGHT CHANCE OF LINGERING
SHOWERS ACROSS ZONE 24 WITH THE THREAT ENDING BY EARLY EVENING
WEDNESDAY. HIGH TEMPS WILL CLIMB A FEW DEGREES AS THE AIRMASS WARMS
UP A BIT...BUT READINGS WILL REMAIN BELOW SEASONAL NORMALS.

THURSDAY...
A DRYING AND SUBSIDENT NORTHERLY FLOW ALOFT WILL SET UP ACROSS THE
AREA AS HIGH PRESSURE ALOFT STARTS TO BUILD ALONG THE CA COAST. THIS
WILL LEAD TO SUNNY SKIES...AND CONTINUED WARMING WITH HIGH TEMPS
REACHING INTO THE LOW TO MID 70S...AND TOWARDS SEASONAL NORMALS.

FRIDAY INTO EARLY NEXT WEEK...
A WARMING TREND IS EXPECTED TO CONTINUE THROUGH THIS PERIOD UNDER
MAINLY CLEAR SKIES AS HIGH PRESSURE STRENGTHENS OVER THE
REGION...WITH A GOOD CHANCE FOR HIGHS NEAR 80 ACROSS THE LOWER
DESERTS BY THE WEEKEND...AND EVEN INTO THE MID 80S BY NEXT TUESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA AND KSDL...
PLENTY OF LOW-LEVEL AND BOUNDARY LAYER MOISTURE REMAINS OVER THE
AREA AND WILL RESULT IN CONTINUED DEVELOPMENT OF CONGESTED CU FIELDS
THROUGH THE EARLY EVENING. UPPER TROUGH AXIS IS ALSO STILL MOVING
THROUGH THE AREA AND WILL ALLOW FOR SHOWER DEVELOPMENT TO POP-UP FOR
THE EVENING. ADDED VCSH MENTION FOR THE REMAINDER OF THE MIDDAY/AFTN
HOURS IN FOR THE PHX TERMINALS. WINDS WILL EVENTUALLY TRANSITION TO
AFTN SOUTHWEST-WEST HEADINGS WITH GNLY LIGHT SPEEDS. MORE ERRATIC
WINDS WITH LOCALIZED GUSTINESS WILL BE POSSIBLE DUE TO
VICINITY/PASSING SHOWERS AND ALONG WITH VERY SHORT WINDOWS OF VSBY
RESTRICTION/LOWERED CIGS.

BOUNDARY LAYER MOISTURE WILL REMAIN SOMEWHAT ELEVATED OVERNIGHT...SO
THERE IS A REMOTE POSSIBILITY OF PATCHY FOG IN THE AM. SOME DRYING
ACROSS THE PHX AREA THIS AFTERNOON SHOULD HELP KEEP THE CROSSOVER
TEMPERATURE AT KPHX AWAY FROM CRITICAL FOG THRESHOLDS FOR WED AM.
LOCAL SREF GUIDANCE HAS REMOTE CHANCES FOR REDUCED VSBYS AGAIN IN
THE AM. WILL HOLD OFF ANY RESTRICTIONS OR BR/FG INCLUSION IN TAFS
ATTM AS UNCERTAINTY IT HIGH FOR A TWO-MORNING-IN-A-ROW EVENT.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
NO AVIATION CONCERNS THROUGH WEDNESDAY MORNING WITH JUST OCCASIONAL
HIGH CLOUDS AND A FEW AFTERNOON CU TO DEAL WITH. SFC WINDS WILL
GENERALLY FAVOR A NORTHWEST DIRECTION...HOWEVER THE WEAK PRESSURE
GRADIENT MAY ALLOW EXTENDED PERIODS OF VARIABLE DIRECTION WITH
SPEEDS AOB 6 KT.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
STRONG HIGH PRESSURE WILL PROVIDE SEASONABLY WARM AND DRY CONDITIONS
TO THE DISTRICT DURING THE END OF OF THIS WEEK INTO EARLY NEXT WEEK.
WITH TEMPERATURES SLIGHTLY ABOVE NORMAL...AFTERNOON HUMIDITY LEVELS
WILL REGULARLY FALL INTO A 15 TO 25 PERCENT RANGE WITH GOOD
OVERNIGHT RECOVERY. WINDS WILL FAVOR A NORTH TO NORTHEAST TRAJECTORY
THROUGH THE PERIOD...WITH SOME OCCASIONAL GUSTINESS OVER RIDGE TOPS
BUT ALL IN ALL VERY TYPICAL SPEEDS. OVERALL...FIRE DANGER WILL BE
LIMITED DURING THIS TIME FRAME.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...PERCHA/CB
AVIATION...NOLTE/MO
FIRE WEATHER...MO


















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