Flash Flood Warning 5, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-050600-

AREA FORECAST DISCUSSION...UPDATED AVIATION DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
430 PM MST TUE SEP 4 2007

.SYNOPSIS...
AN INCREASE IN MOISTURE WILL SUPPORT ISOLATED THUNDERSTORMS MAINLY
OVER FAR SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THIS EVENING.
HURRICANE HENRIETTE...CURRENTLY NEAR THE SOUTHERN TIP OF BAJA
CALIFORNIA...WILL WEAKEN AND MOVE SLOWLY TOWARD THE NORTH DURING THE
NEXT COUPLE OF DAYS. AS THIS OCCURS...MOISTURE WILL BE ON THE
INCREASE OVER SOUTHWEST AND SOUTH-CENTRAL ARIZONA...WITH A CHANCE
FOR SHOWERS AND THUNDERSTORMS MAINLY OVER SOUTH-CENTRAL ARIZONA
WEDNESDAY EVENING THROUGH THURSDAY NIGHT. A SLIGHT CHANCE FOR A
SHOWER OR STORM WILL CONTINUE ON FRIDAY...BUT DRIER AND WARMER
WEATHER WILL RETURN TO THE REGION SATURDAY THROUGH MONDAY.

&&

.SHORT TERM...
TONIGHT THROUGH FRIDAY...
MAJOR FORECAST CHALLENGE CENTERS ON DEGREE OF MOIST ADVECTION AND
PRECIP CHANCES AS WEAKENING/DISSIPATING HENRIETTE PASSES TO THE
SOUTH AND EAST OF THE FORECAST AREA.

IMPRESSIVE LOW LEVEL MOIST ADVECTION FROM THE GULF OF CALIFORNIA HAS
BEEN ONGOING MAINLY OVER FAR SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA TODAY. KYUX VWP INDICATES MAIN PUSH OF MOISTURE HAD OCCURRED
IN THE LOWEST MILE AGL...WITH SFC DEW POINTS OVER AND WEST OF THE
LOWER COLORADO RIVER STILL IN THE UPPER 60S TO LOW 70S AS OF 3 PM.
COMBINED WITH STEEP LOW-MID LEVEL LAPSE RATE...TSTM DEVELOPMENT
OCCURRED MAINLY OVER HIGHER TERRAIN OF SOUTHWEST MARICOPA
COUNTY...CENTRAL LA PAZ COUNTY...NORTHERN BAJA CALIFORNIA...AND
HIGHER TERRAIN JUST WEST OF IMPERIAL COUNTY EARLIER THIS
AFTERNOON...WITH INTENSE STORMS PROPAGATING/DEVELOPING SLOWLY TOWARD
THE EAST OVER WESTERN IMPERIAL COUNTY AS OF 4 PM. HAVE BUMPED POP UP
A BIT OVER THE ENTIRE CWA FOR THIS EVENING...WITH BIGGEST INCREASE
OVER FAR SOUTHEAST CALIFORNIA.

HENRIETTE IS STILL FORECAST TO WEAKEN AND MOVE SLOWLY TOWARD THE
NORTH DURING THE NEXT COUPLE OF DAYS...WHILE A VIGOROUS TROUGH IN
THE WESTERLIES MOVES SLOWLY EAST ACROSS THE INTERMOUNTAIN WEST. NHC
FORECASTS REGARDING HENRIETTE HAVE BEEN VERY CONSISTENT...AS HAS
NUMERICAL GUIDANCE REGARDING HENRIETTE AND THE VIGOROUS TROUGH IN
THE WESTERLIES (LATEST INFORMATION REGARDING HENRIETTE WILL BE
PROVIDED BY THE NATIONAL HURRICANE CENTER (WWW.NHC.NOAA.GOV)).
INTERACTION BETWEEN THESE TWO SYSTEMS SHOULD RESULT IN A MOISTURE
INCREASE ACROSS THE EASTERN HALF OF THE CWA DURING THE NEXT 24-36
HRS...WITH AN INCREASED CHANCE FOR SHOWERS AND THUNDERSTORMS OVER
THE AZ PORTION OF THE CWA BY WEDNESDAY EVENING. OF COURSE...BIG WILD
CARDS CONTINUE TO BE THE DEGREE OF MOIST ADVECTION AND UPPER SUPPORT
OVER OUR CWA. ATTM...BEST CHANCE FOR SIGNIFICANT PRECIP APPEARS TO
BE OVER SOUTHEAST AZ...SOUTH AND EAST OF OUR CWA...THE AREA CLOSEST
TO THE TRACK OF HENRIETTE REMNANTS. FOR NOW...CHANCE POPS APPEAR
REASONABLE FOR SOUTH CENTRAL AZ WEDNESDAY EVENING THROUGH THURSDAY
EVENING. A DRYING TREND WILL COMMENCE BY FRIDAY...BUT A SLIGHT
CHANCE FOR A STORM WILL CONTINUE OVER SOUTH-CENTRAL AZ GIVEN
UNCERTAINTY REGARDING STABILITY/MOISTURE AVAILABILITY.

&&

.LONG TERM...
FRIDAY NIGHT THROUGH TUESDAY...
POPS AND CLOUDS WILL DECREASE FROM THE WEST OVER SOUTH-CENTRAL AZ
FRIDAY EVENING AS THE REMNANTS OF HENRIETTE MOVE EAST OF OUR AREA.
CONTINUED DRYING IS ON TAP SATURDAY INTO EARLY NEXT WEEK AS A
WESTERLY FLOW ALOFT MOVES INTO ARIZONA. AS SUCH POPS WILL DROP OFF
QUITE A BIT...AND HIGH TEMPERATURES WILL RISE TO SLIGHTLY ABOVE
NORMAL LEVELS...SUNDAY THROUGH TUESDAY.

&&

.AVIATION...
SEPTEMBER 4 2010 UTC (SEPTEMBER 4 1310 MST)

LOW TO MID LEVEL MOISTURE INCREASE FROM THE SOUTH THIS PAST 24 HOURS
HAS LEAD TO INCREASING INSTABILITY OVER THE SOUTH-CENTRAL DESERTS.
ISOLATED THUNDERSTORMS WILL CONTINUE TO DEVELOP OVER SOUTHWEST
MARICOPA COUNTY (40-50NM SW OF KPHX) THROUGH 0000 UTC...WITH A
SLIGHT CHANCE OF THUNDERSTORMS DEVELOPING CLOSER TO THE KPHX/KIWA
AIRFIELDS AFTER 0100 UTC. AS A MATTER OF FACT...GIVEN THE LOW LEVEL
INCREASE FROM SOUTHEAST CALIFORNIA TO SOUTHERN GILA COUNTY (ACROSS
OUR ENTIRE FORECAST AREA)...WE CANNOT RULE OUT THE SLIGHT CHANCE FOR
THUNDERSTORMS AT ANY OF THE FIVE TAF SITES. AT THIS TIME...
CONFIDENCE REMAINS LOW FOR DIRECT AIRFIELD IMPACT...SO WILL GO WITH
CB IN THE TAFS. WILL MONITOR CLOSELY AS AFTERNOON WEARS ON...AND
AMEND TAFS AS NECESSARY.

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

AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SEPTEMBER 4 2320 UTC (SEPTEMBER 4 430 PM MST)

QUITE A BIT OF UNCERTAINTY IN THE FORECAST LATE WEDNESDAY THROUGH
FRIDAY DUE TO POSSIBLE IMPACTS FROM THE REMNANTS OF A TROPICAL
SYSTEM. AT THIS TIME...IT APPEARS THAT CLOUD COVER...RH VALUES...AND
PRECIPITATION CHANCES WILL BEGIN TO INCREASE ACROSS THE EASTERN HALF
OF THE FORECAST AREA/MARICOPA COUNTY EAST/LATE WEDNESDAY... AND
REMAIN ELEVATED THROUGH FRIDAY...BUT THE BULK OF THE RAINFALL IS
EXPECTED TO IMPACT THE SOUTHEAST CORNER OF AZ. THE SYSTEM SHOULD BE
MOVING OFF TO THE EAST BY LATE FRIDAY. WEAK HIGH PRESSURE WILL BUILD
BACK OVER THE REGION OVER THE WEEKEND...RESULTING IN DECREASING RH
VALUES AND SLOWLY INCREASING TEMPERATURES.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

SHORT TERM...DG
LONG TERM...DG
AVIATION...WANEK
FIRE WX...INIGUEZ

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
634 AM MST TUE SEP 4 2007

AZZ022-023-027-028-050100-
NORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREA-
SOUTHWEST MARICOPA COUNTY-
NORTHWEST AND NORTH CENTRAL PINAL COUNTY-
634 AM MST TUE SEP 4 2007

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT CHANCE FOR LATE AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS...WITH THE PRIMARY HAZARD BEING GUSTY WINDS TO OVER 40
MPH AS WELL AS BLOWING DUST AND BRIEF HEAVY RAIN.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

AN INFLUX OF TROPICAL MOISTURE FROM THE SOUTH WILL LEAD TO AN
INCREASED CHANCE FOR SHOWERS AND THUNDERSTORMS LATER WEDNESDAY
THROUGH EARLY FRIDAY. LOCALLY HEAVY RAINFALL AND FLASH FLOODING ARE
POSSIBLE WITH THE THUNDERSTORMS...AS WELL AS SOME BLOWING DUST AND
GUSTY WINDS TO 40 MPH. THE AIRMASS WILL START DRYING FROM THE WEST
FRIDAY EVENING...WITH A SIGNIFICANT DRYING TREND EXPECTED THROUGH THE
WEEKEND AND INTO NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

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

AZZ024-050100-
SOUTHERN GILA COUNTY/TONTO NATIONAL FOREST FOOTHILLS-
634 AM MST TUE SEP 4 2007

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT CHANCE FOR AFTERNOON AND EVENING
THUNDERSTORMS...WITH THE PRIMARY HAZARD BEING LOCALLY HEAVY RAINFALL
AND GUSTY WINDS TO AROUND 40 MPH.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

INCREASING TROPICAL MOISTURE FROM THE SOUTH WILL LEAD TO A GOOD
CHANCE FOR SHOWERS AND THUNDERSTORMS BEGINNING WEDNESDAY EVENING AND
CONTINUING THROUGH ABOUT FRIDAY. LOCALLY HEAVY RAINFALL AND FLASH
FLOODING ARE POSSIBLE WITH STRONGER STORMS...AND THERE ALSO COULD BE
GUSTY WINDS TO 40 MPH AS WELL AS DEADLY CLOUD TO GROUND LIGHTNING.
CHANCES FOR THUNDERSTORMS WILL DECREASE THROUGHOUT THE WEEKEND AS
DRIER AIR BEGINS TO MOVE IN FROM THE WEST.

.SPOTTER INFORMATION STATEMENT...

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

AZZ020-021-025-026-CAZ030>033-050100-
LOWER COLORADO RIVER VALLEY AZ-WEST CENTRAL DESERTS-
YUMA/MARTINEZ LAKE AND VICINITY-SOUTHWEST DESERTS-
JOSHUA TREE NATIONAL PARK-LOWER COLORADO RIVER VALLEY CA-
RIVERSIDE COUNTY/EASTERN DESERTS-IMPERIAL COUNTY-
634 AM MST TUE SEP 4 2007 /634 AM PDT TUE SEP 4 2007/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EXTREME
SOUTHWEST ARIZONA...EXTREME WEST-CENTRAL ARIZONA...SOUTHWEST
ARIZONA...WEST-CENTRAL ARIZONA...EXTREME SOUTHEAST CALIFORNIA AND
SOUTHEAST CALIFORNIA.

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT CHANCE FOR AFTERNOON AND EVENING
THUNDERSTORMS...WITH THE PRIMARY HAZARD BEING GUSTY WINDS TO OVER 45
MPH...AS WELL AS LOWERED VISIBILITY IN BLOWING DUST OR SAND. BRIEF
HEAVY RAIN IS ALSO POSSIBLE WITH STRONGER STORMS. STORMS ARE EXPECTED
TO BE VERY ISOLATED SHOULD THEY DEVELOP AT ALL.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

IN INCREASE IN TROPICAL MOISTURE FROM THE SOUTH WILL LEAD TO
INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS...BEGINNING WEDNESDAY
AFTERNOON AND CONTINUING THROUGH THURSDAY NIGHT. LOCALLY HEAVY RAIN
IS POSSIBLE WITH STRONGER STORMS...AS WELL AS GUSTY WINDS TO OVER 40
MPH AND LOW VISIBILITY IN BLOWING DUST. CHANCES FOR STORMS SHOULD
GENERALLY BE LESS THAN 30 PERCENT...WITH THE BEST THREAT BEING THE
AREA EAST OF THE LOWER COLORADO RIVER VALLEY.

A DRYING TREND WILL BEGIN FROM THE WEST FRIDAY AFTERNOON...LEADING TO
FEW IF ANY THUNDERSTORMS FROM SATURDAY AFTERNOON INTO NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

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

CB