Severe Thunderstorm Warning 59, NWS Phoenix, AZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
200 PM MST FRI SEP 13 2013

.SYNOPSIS...
A DRY WESTERLY FLOW ALOFT WILL DOMINATE ACROSS THE DESERT SOUTHWEST
INTO NEXT WEEK. A GRADUAL WARMING TREND IS IN STORE WITH HIGH
TEMPERATURES AROUND NORMAL TODAY AND SLIGHTLY ABOVE NORMAL THIS
WEEKEND THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.

&&

.DISCUSSION...
DEWPOINTS HAVE INCREASED ACROSS SOUTH-CENTRAL AZ INTO THE 60S AND CU
FIELD CONTINUES TO BECOME MORE ORGANIZED ACROSS NORTHERN AND EASTERN
AZ. MEANWHILE...A WELL-DEFINED VORT MAX ROTATING AROUND THE PARENT
UPPER LOW IN NV...IS EVIDENT ON WV IMAGERY ACROSS CENTRAL AZ.
INCREASING PVA WILL CONSEQUENTLY HELP TO FORCE ISOLATED CONVECTION
FROM PHOENIX NORTH AND EASTWARD THIS AFTERNOON.

LATEST MESOANALYSIS SHOWS MLCAPES IN EXCESS OF 1000 J/KG ACROSS THE
PHOENIX AREA WITH A WEAK CAP IN PLACE ACROSS WESTERN MARICOPA AND LA
PAZ COUNTIES...LIKELY DUE TO AN ISOTHERMAL LAYER AROUND 600 MB. THE
CAP CONTINUES TO ERODE...THOUGH HI-RES CAMS SUGGEST THAT ONLY
ISOLATED CELLS ARE EXPECTED IN THE LOWER DESERTS INCLUDING PHOENIX.
MAIN THREAT FROM ANY STORMS THAT DEVELOP WILL BE LOCALIZED HEAVY
RAIN...STRONG WIND GUSTS AND BLOWING DUST. QG AND THERMODYNAMIC
FORCING FOR ASCENT WILL WANE BY LATE THIS AFTERNOON AND THIS
EVENING...RESULTING IN A RAPID CLEARING TREND.

&&

.PREVIOUS DISCUSSION...
POP CHANCES FOR SATURDAY WILL BASICALLY MIRROR TODAY/S WITH VERY
LITTLE CHANGE IN AIRMASS CONDITIONS. LOOKING AT TEMPERATURES...THE
WARMING TREND WILL BE GRADUAL BUT BY SATURDAY OR SUNDAY...MOST
AREAWIDE HIGHS WILL TOP SEASONAL NORMALS.

ON THE LARGE SCALE...AFTER THIS PESKY UPPER FLOW FINALLY
VACATES THE WESTERN STATES BY SUNDAY...AN WEAK UPPER RIDGE WILL BE
SET TO TRAVERSE ACROSS THE REGION SUNDAY INTO EARLY MONDAY. THIS
WILL HELP TO HEAT THINGS UP EVEN MORE WITH LOWER DESERT SPOTS ACROSS
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA PEAKING OUT BETWEEN
104-108 AND 102-105 ACROSS SOUTH-CENTRAL ARIZONA LOCATIONS. BY
MONDAY...THE DRY WESTERLY LOW LEVEL FLOW FINALLY OVERTAKES AREAS
ACROSS SOUTHEAST ARIZONA...ENDING ANY CHANCES FOR SHOWERS AND
THUNDERSTORMS. A MORE WESTERLY ZONAL PATTERN SETS UP ACROSS THE
DESERT SOUTHWEST NEXT WEEK AS A SLOW MOVING UPPER LOW AFFECTS THE
PACIFIC NORTHWEST. FROM TUESDAY ON...AREAWIDE POPS WILL LESS THAN 10
PERCENT. LONG RANGE MODELS ARE IN GOOD AGREEMENT OVERALL BRINGING
LOWERING 500MB HEIGHTS AS THE LARGE SCALE TROUGHING OVER THE PACIFIC
NORTHWEST SLOWLY SAGS SOUTHWARD INTO THE DESERT SOUTHWEST BY LATE
NEXT WEEK. TIMING OF THIS MAY BE OFF BY A DAY OR SO...BUT WE SHOULD
START TO SEE A DECLINING TEMPERATURE TREND BY NEXT THURSDAY OR
FRIDAY.

&&

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

SOUTHWEST TO WEST FLOW ALOFT WILL KEEP SKIES MOSTLY CLEAR OVER THE
NEXT 24 HOURS. ANY THUNDERSTORM ACTIVITY WILL BE CONFINED TO HIGHER
TERRAIN WELL TO THE EAST OF PHOENIX. A FEW AFTERNOON HIGH BASED
CUMULUS ARE POSSIBLE ACROSS THE CENTRAL DESERTS WITH BASES GENLY AOA
9K FEET. WINDS WILL BE QUITE LIGHT AND SHOULD FOLLOW NORMAL DIURNAL
PATTERNS THROUGH SATURDAY MORNING. NO AVIATION CONCERNS AT ANY
AIRFIELD NEXT 24 HOURS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
A DRY AND WARM WEATHER PATTERN IS EXPECTED THROUGH THE FORECAST
PERIOD...AS WEAK WEST TO SOUTHWEST FLOW REMAINS OVER THE REGION.
AFTERNOON HIGH TEMPERATURES WILL AVERAGE ABOUT 3 TO 5 DEGREES ABOVE
NORMAL. THE DRIER AIR WILL DROP THUNDERSTORM CHANCES BELOW 10
PERCENT FOR THE EARLY PART OF NEXT WEEK...WITH THE MAJORITY OF THE
LOWER DESERT ELEVATIONS EXPECTED TO STAY DRY. WINDS WILL BE
GENERALLY LIGHT AND WILL FOLLOW TYPICAL DRAINAGE PATTERNS...WITH
AFTERNOON AND EARLY EVENING BREEZINESS EXPECTED. MINIMUM RELATIVE
HUMIDITIES WILL FALL MOSTLY INTO THE TEENS IN THE LOWER DESERTS
DURING THE AFTERNOON...BUT GOOD OVERNIGHT RECOVER WILL OCCUR WITH
READINGS RISING ABOVE 35 PERCENT MOST EVENINGS.

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

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

DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...KUHLMAN
AVIATION...CB
FIRE WEATHER...MCLANE/CB

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
352 AM MST FRI SEP 13 2013

AZZ024-141200-
SOUTHERN GILA COUNTY/TONTO NATIONAL FOREST FOOTHILLS-
352 AM MST FRI SEP 13 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST-CENTRAL ARIZONA.

.DAY ONE...TODAY AND TONIGHT.

ISOLATED TO SCATTERED THUNDERSTORMS WILL BE POSSIBLE DURING THE
DAYTIME HOURS TODAY. THE PRIMARY WEATHER HAZARDS WILL BE GUSTY WINDS
IN EXCESS OF 45 MPH...BRIEF HEAVY DOWNPOURS...AND DEADLY LIGHTNING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

ISOLATED TO SCATTERED THUNDERSTORMS WILL BE POSSIBLE DURING THE
DAYTIME HOURS SATURDAY BEFORE DECREASING CHANCES OCCUR ON SUNDAY AND
LITTLE IF ANY CHANCE NEXT WEEK. THE PRIMARY WEATHER HAZARDS ON
SATURDAY WILL BE GUSTY WINDS IN EXCESS OF 45 MPH...BRIEF HEAVY
DOWNPOURS...AND DEADLY LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

AZZ020>023-025>028-CAZ030>033-141200-
LOWER COLORADO RIVER VALLEY AZ-WEST CENTRAL DESERTS-
NORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREA-
YUMA/MARTINEZ LAKE AND VICINITY-SOUTHWEST DESERTS-
SOUTHWEST MARICOPA COUNTY-NORTHWEST AND NORTH CENTRAL PINAL COUNTY-
JOSHUA TREE NATIONAL PARK-LOWER COLORADO RIVER VALLEY CA-
RIVERSIDE COUNTY/EASTERN DESERTS-IMPERIAL COUNTY-
352 AM MST FRI SEP 13 2013 /352 AM PDT FRI SEP 13 2013/

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

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PHOENIX AZ
141 PM MST FRI SEP 13 2013

AZZ024-132130-
GILA AZ-PINAL AZ-
141 PM MST FRI SEP 13 2013

...SIGNIFICANT WEATHER ADVISORY...

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

SIGNIFICANT WEATHER ADVISORY FOR...
  SOUTH CENTRAL GILA COUNTY IN EAST CENTRAL ARIZONA
  NORTH CENTRAL PINAL COUNTY IN SOUTH CENTRAL ARIZONA

UNTIL 230 PM MST

AT 135 PM MST...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 5 MILES EAST OF PINAL PEAK...MOVING NORTHEAST AT
15 MPH. ANOTHER STORM CELL WAS LOCATED ON THE EAST SIDE OF TOP OF
THE WORLD...ALSO MOVING NORTHEAST. STATE ROUTE 77 AND U.S. HIGHWAY
60 CAN EXPECT PONDING OF WATER ON THE ROADWAYS...AND DRIVING
CONDITIONS MAY CHANGE RAPIDLY.

WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH
FREQUENT DANGEROUS LIGHTNING.

LOCATIONS IMPACTED INCLUDE...
   GLOBE AND  CLAYPOOL...
   CUTTER...
   SAN CARLOS...
   TOP OF THE WORLD...

IF THIS STORM INTENSIFIES...A WARNING MAY BE NEEDED. STAY TUNED TO
NOAA WEATHER RADIO...LOCAL RADIO OR TV FOR THE LATEST UPDATES.

SOME UNSECURED OBJECTS COULD BE BLOWN AROUND. SEEK SHELTER INDOORS
UNTIL THE STORM PASSES.

LAT...LON 3338 11042 3338 11043 3337 11044 3306 11083
      3336 11103 3366 11075 3342 11037
TIME...MOT...LOC 2040Z 227DEG 13KT 3332 11072

DEWEY

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PHOENIX AZ
213 PM MST FRI SEP 13 2013

AZZ024-028-132200-
PINAL AZ-
213 PM MST FRI SEP 13 2013

...SIGNIFICANT WEATHER ADVISORY...

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

SIGNIFICANT WEATHER ADVISORY FOR...
  NORTH CENTRAL PINAL COUNTY IN SOUTH CENTRAL ARIZONA

UNTIL 300 PM MST

AT 208 PM MST...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM NEAR BOYCE THOMPSON ARBORETUM...MOVING EAST AT 5
MPH.

BRIEF HEAVY RAINFALL AND WIND GUSTS UP TO 45 MPH ARE EXPECTED WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
   BOYCE THOMPSON ARBORETUM...
   SUPERIOR...

LAT...LON 3340 11107 3323 11107 3322 11130 3339 11129
TIME...MOT...LOC 2112Z 270DEG 6KT 3329 11119

MEYERS