Dust Storm Warning 6, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-170600-

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
355 PM MST WED MAY 16 2007

SOUTH-CENTRAL AND SOUTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA
FORECAST DISCUSSION

.SYNOPSIS...
AN INCREASE IN MOISTURE FROM THE SOUTHEAST WILL RESULT IN A CHANCE OF
SHOWERS AND THUNDERSTORMS MAINLY OVER THE HIGHER TERRAIN EAST OF
PHOENIX THIS EVENING. STRONG GUSTY WINDS AND DENSE BLOWING DUST WILL
BE POSSIBLE OVER PORTIONS OF THE SOUTH-CENTRAL DESERT AREAS...
INCLUDING THE GREATER PHOENIX AREA...THIS EVENING...ALONG WITH A
SLIGHT CHANCE FOR A THUNDERSTORM. THERE WILL BE A SLIGHT CHANCE FOR
AFTERNOON AND EVENING THUNDERSTORMS OVER THE HIGHER TERRAIN OF SOUTH
CENTRAL ARIZONA THURSDAY AND FRIDAY. OTHERWISE...DRY WEATHER WITH
MOSTLY CLEAR NIGHTS AND SUNNY DAYS THIS WEEKEND INTO THE MIDDLE OF
NEXT WEEK. DAYTIME HIGHS WILL LOWER A FEW DEGREES BY EARLY NEXT WEEK
AS A WEATHER SYSTEM PASSES MAINLY TO OUR NORTH.

&&

.SHORT TERM...
TONIGHT THROUGH SATURDAY...
VISIBLE SATELLITE SHOWS WIDESPREAD THUNDERSTORM ACTIVITY NORTH OF
THE RIM AND OVER NE PORTIONS OF THE STATE. LOTS OF MID-LEVEL
MOISTURE CONTINUES TO CONVERGE INTO THIS AREA...EXPECT STORMS ALONG
THE RIM TO BACKBUILD TO THE SOUTH-SOUTHWEST AS THE EVENING
PROGRESSES. OUTFLOWS FROM THESE HIGHBASED STORMS COULD MAKE IT INTO
THE PHOENIX METRO AREA...WHERE SFC DEWPOINTS HAVE STAYED IN THE
UPPER 40S AND DAYTIME HEATING HAS BEEN AMPLE (UPPER 90S)...
SUFFICIENT TO SUPPORT ADDITIONAL STORM DEVELOPMENT ACROSS THE
CENTRAL DESERTS IN MARICOPA AND PINAL COUNTIES. SOME STORM ACTIVITY
BECOMING MORE ORGANIZED AND MOVING NORTH FROM TUCSON...POSING SOME
CONCERN FOR STRONG GUSTY OUTFLOWS TO PUSH INTO THE PHOENIX AREA FROM
THE SOUTH. AS MENTIONED EARLIER...THE GFS MODEL SOUNDING HAS MODEST
AMOUNT OF PWATER THAT QUICKLY ESTABLISHES OVER KPHX THIS EVENING
(AROUND .80 IN)...AND SIMILAR AMOUNTS INTO HIGHER TERRAIN OF ERN
ZONES. HOWEVER...SOUNDING PROFILES ARE INVERTED-V...SO THE MAIN
THREAT FROM THESE STORMS WILL BE HIGH BASED THUNDERSTORMS...STRONG
GUSTY OUTFLOW WINDS UP TO 40 KTS...AND AREAS OF BLOWING DUST ACROSS
THE DESERTS THAT COULD RAPIDLY REDUCE VISIBILITY.

THE UPPER LEVEL DISTURBANCE SLOWLY MOVES EAST OVERNIGHT...AND
ACTIVITY/POPS WILL DIMINISH...LINGERING OVER THE HIGHER TERRAIN OF
SOUTHERN GILA COUNTY INTO THE EARLY MORNING HOURS. THURSDAY AND
FRIDAY BOTH HOLD FOR A SIMILAR SCENARIO...WITH SUFFICIENT MOISTURE
IN PLACE AND GOOD INSOLATION...COULD SEE AFTERNOON AND EVENING
THUNDERSTORMS FORM AGAIN NORTH AND EAST OF PHOENIX. OTHERWISE...DRY
WEATHER WITH MOSTLY CLEAR NIGHTS AND SUNNY DAYS WITH DAY TO DAY
TEMPERATURE CHANGE IS EXPECTED THE REST OF THIS WEEK...ESPECIALLY IN
SOUTHEAST CALIFORNIA INTO SOUTHWEST ARIZONA WHERE A DRY W-SWLY FLOW
WILL PREVAIL.

&&

.LONG TERM...
SATURDAY NIGHT THROUGH WEDNESDAY...
ENSEMBLE GUIDANCE AND LATEST OPERATIONAL ECMWF/GFS SUPPORT IDEA THAT
PRINCIPAL UPPER LEVEL RIDGE POSITIONS WILL BE OVER THE EASTERN THIRD
OF THE U.S. AND JUST OFF THE WEST COAST...WITH PRINCIPAL TROUGH OVER
THE WEST-CENTRAL UNITED STATES. AS FAR AS DAY-TO-DAY DETAILS ARE
CONCERNED...DURING SUN-TUE PERIOD...VIGOROUS WEATHER DISTURBANCE IS
PROGGED TO MOVE EAST ACROSS NORTHWEST/NORTH-CENTRAL STATES...MAINLY
NORTH OF OUR FORECAST AREA. AS THIS OCCURS...700 MB FLOW EXPECTED TO
MAINTAIN A SOUTHERLY COMPONENT WHICH SHOULD HELP MAINTAIN SOME
LOW-MID LEVEL MOISTURE OVER THE REGION. SO...KEPT DEW POINTS NEAR OR
SLIGHTLY ABOVE CLIMO...ESPECIALLY MON-TUE. 500 MB HEIGHTS FORECAST
TO LOWER ABOUT 60 GPM FROM CURRENT LEVELS...TO AROUND 5760 GPM...BY
MONDAY AFTN THRU TUESDAY...AND LOW-LEVEL TEMPS FORECAST TO LOWER A
BIT EACH DAY SUN THRU TUES...SO HAVE MIRRORED THIS TREND IN MAX TEMP
FORECAST...WITH MAX TEMPS NEAR OR SLIGHTLY ABOVE CLIMO BY NEXT
TUESDAY (MID TO UPPER 90S OVER MOST OF THE LOWER DESERT). BY THE
MIDDLE OF NEXT WEEK...TROUGH AXIS EDGES OFF TO OUR EAST WHILE RIDGE
BEGINS TO BUILD IN FROM THE WEST...WHICH SHOULD RESULT IN WARMER MAX
TEMPS AND LOWER SFC DEW POINT TEMPS.

&&

.AVIATION...
AN UPPER LEVEL DISTURBANCE MOVING THROUGH SOUTH-CENTRAL ARIZONA WILL
INCREASE CHANCES OF ISOLD SHWRS/TSTMS MAINLY OVER THE HIGHER TERRAIN
EAST OF PHOENIX THIS EVENING. HOWEVER...GIVEN RATHER ORGANIZED LOOK
TO CONVECTION CURRENTLY AFFECTING TUCSON METRO AND POINTS NORTH...
EXPECT GUSTY SOUTHEAST WINDS AND AREAS OF DENSE BLOWING DUST TO PUSH
NORTH AND WEST ACROSS SOUTHEAST PINAL COUNTY DURING THE NEXT COUPLE
OF HOURS...AND AFFECT THE PHOENIX METRO AREA...INCLUDING KIWA AND
KPHX...AS EARLY AS 7 PM (0200Z) THIS EVENING. VSBY COULD BE LOWER
THAN CURRENT TAFS INDICATE...WILL WATCH CLOSELY AND UPDATE TAFS AS
NEEDED. ALSO...ISOLATED STORMS WILL LIKELY BE TRIGGERED OVER AND
NEAR KIWA/KPHX BY THE OUTFLOW WINDS. NOT EXPECTING QUITE AS MUCH
ACTIVITY OVER SOUTH-CENTRAL DESERT THURSDAY EVENING...WITH FOCUS OF
STORM ACTIVITY A BIT FURTHER EAST. MEANWHILE...NO SIG WEATHER
EXPECTED TO AFFECT WRN TAF SITES (KIPL...KBLH... KYUM) OVER THE NEXT
SEVERAL DAYS.

SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL
FOR MORE DETAILED INFORMATION.

AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
STRONG HIGH PRESSURE WILL DOMINATE THE WEATHER FOR THE REST OF THE
WEEK...WITH THE ATMOSPHERE DRY AND STABLE OVER ALL BUT EASTERN
ARIZONA. INCREASED MOISTURE OVER THIS PORTION OF THE STATE WILL
KEEP A THREAT OF AFTERNOON AND EVENING THUNDERSTORMS...MAINLY
DRY...OVER THE HIGHER TERRAIN EAST OF PHOENIX (SOUTHERN GILA COUNTY)
THROUGH SATURDAY. A DRY SOUTHWEST FLOW WILL SET UP SUNDAY INTO EARLY
NEXT WEEK...BRINGING SLIGHTLY COOLER TEMPERATURES AND OCCASIONAL
AFTERNOON AND EVENING BREEZES TO THE AREA.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

MEYERS/DG

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE PHOENIX AZ
611 AM MST WED MAY 16 2007

AZZ022-023-027-028-171315-
NORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREA-
SOUTHWEST MARICOPA COUNTY-
NORTHWEST AND NORTH CENTRAL PINAL COUNTY-
611 AM MST WED MAY 16 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH-CENTRAL
ARIZONA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP EAST OF THE PHOENIX
METRO AREA THIS AFTERNOON AND EVENING. THE THUNDERSTORMS WILL LIKELY
GENERATE OUTFLOW BOUNDARIES...WITH WINDS GUSTING TO 40 MPH OR
HIGHER...WHICH WILL MOVE INTO MARICOPA AND NORTHWEST PINAL COUNTIES
FROM THE EAST. THE STRONG WINDS WILL CAUSE AREAS OF BLOWING DUST TO
DEVELOP...REDUCING VISIBILITY TO TWO MILES OR LESS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS ARE EXPECTED TO DEVELOP EAST OF PHOENIX AGAIN THURSDAY
AND FRIDAY.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

AZZ024-171315-
SOUTHERN GILA/TONTO NF FOOTHILLS-
611 AM MST WED MAY 16 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST-CENTRAL
ARIZONA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS THE AREA THIS
AFTERNOON AND EVENING. SOME OF THE STRONGER THUNDERSTORMS COULD
PRODUCE STRONG WINDS IN EXCESS OF 45 MPH...FREQUENT CLOUD TO GROUND
LIGHTNING...AND BRIEF HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS ARE EXPECTED TO DEVELOP AGAIN THURSDAY AND FRIDAY.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

SPOTTER ACTIVATION WILL NOT BE NEEDED.

INIGUEZ