Area Forecast Discussion
Issued by NWS Phoenix, AZ

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KPSR 310345
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
845 PM MST THU JUL 30 2015

.SYNOPSIS...
ISOLATED TO SCATTERED STORM ACTIVITY IS ANTICIPATED OVER ARIZONA AND
SOUTHEAST CALIFORNIA THE REST OF THIS AFTERNOON AND EVENING AND AGAIN
FRIDAY. A NOTABLE DOWNTREND IN MOISTURE FROM WEST TO EAST IS EXPECTED
OVER THE WEEKEND. THIS WILL KEEP STORM CHANCES LIMITED TO SOUTH-
CENTRAL ARIZONA WELL INTO NEXT WEEK.

&&

.DISCUSSION... IT WAS ANOTHER INTERESTING MONSOON EVENING ACROSS THE
WESTERN PORTION OF THE AREA...FROM YUMA/LA PAZ COUNTIES WESTWARD TO
JOSHUA TREE...AS SCATTERED TO NUMEROUS SHOWERS AND STORMS DEVELOPING
DURING THE AFTERNOON HOURS...THEN STEADILY AND SLOWLY PROGRESSED
WESTWARD ALONG THE LEADING EDGE OF STRONG OUTFLOW BOUNDARIES.
OVERALL...DYNAMICS WERE SOMEWHAT MINIMAL TODAY AS AN INVERTED
TROF/VORT MAX WAS LOCATED ACROSS CENTRAL AZ AND THE LOWER DESERTS
WERE ON THE BACK SIDE OF THIS FEATURE AND UNDER A MORE SUBSIDENT
REGIME. AT LEAST...THIS WAS TRUE OVER SOUTH CENTRAL AZ WHERE FEW IF
ANY STORMS DEVELOPED THIS AFTERNOON AND EVENING UNDER PARTLY SUNNY
SKIES. CAPE AND PWAT APPEARED TO BE HIGHER ACROSS THE WESTERN
DESERTS THIS EVENING AND THIS HELPED EXPLAIN THE MUCH HIGHER LEVELS
OF CONVECTION THAT OCCURRED. STILL...THE MOST LIKELY DRIVER FOR THE
WIDESPREAD CONVECTION WAS BOUNDARY INTERACTION...TYPICAL DURING THE
CENTRAL PORTION OF OUR MONSOON. SEVERAL SMALL STREAM FLOOD ADVISORIES
WERE ISSUED OVER THE COURSE OF THE LATE AFTERNOON AND EVENING...WITH
THE MOST WIDESPREAD CONVECTION OVER CENTRAL LA PAZ AND MUCH OF
EASTERN RIVERSIDE COUNTIES. THE AREAS AROUND DESERT CENTER AND
QUARTZSITE WERE THE HARDEST HIT BY RAINFALL BUT NO REPORTS OF
SERIOUS FLASH FLOODING HAVE YET TO BE RECEIVED FOR THOSE AREAS.

AS OF 830 PM MOST OF THE STORMS HAD DISSIPATED ALTHOUGH ISOLATED
THUNDERSTORMS CONTINUE TO FIRE WELL TO THE SOUTHWEST OF THE GREATER
PHOENIX AREA...IN LOCALES SUCH AS SOUTH CENTRAL YUMA COUNTY AND NEAR
THE MARICOPA/PIMA COUNTY LINE. FOR THE REST OF TONIGHT...THERE WILL
BE A CONTINUED WEAK SOUTHERLY STEERING FLOW ACROSS THE AREA...AND WE
WILL BE BEHIND THE EXITING INVERTED TROF UNDER WEAK ANTICYCLONIC
FLOW ALOFT. THUS...EXPECT ONLY ISOLATED STORMS AT BEST OVER THE
LOWER DESERTS...WITH BETTER CHANCES OVER THE WESTERN DESERTS WHERE
MOISTURE AND CAPE REMAIN A BIT HIGHER. FORECASTS HAVE BEEN TWEAKED
TO REFLECT CURRENT SKY AND WEATHER TRENDS AND LOOK TO BE IN GOOD
SHAPE.

.PREVIOUS DISCUSSION...
STORM ACTIVITY OVER ARIZONA SO FAR HAS BEEN LIMITED IN AREA FOCUSING
INITIALLY OVER WESTERN YAVAPAI THEN SPREADING INTO MOHAVE AND LA PAZ
COUNTIES. THIS HAS BEEN AIDED BY A VORT MAX CENTERED OVER NORTHERN
ARIZONA. IT WILL MOVE SLOWLY NORTH AND NORTHWESTWARD WITH TIME. WITH
THAT TRAJECTORY IT WILL TEND TO HAVE A DECREASING IMPACT ON OUR
FORECAST AREA WITH TIME...ESPECIALLY BY LATE EVENING. OVER SOUTHEAST
CALIFORNIA...ACTIVITY HAS BEEN ISOLATED TO THE VICINITY OF 29 PALMS
AND JOSHUA TREE NATIONAL PARK. THIS IS CLOSE TO A SHORT WAVE ON THE
FAR NORTHERN PERIPHERY OF AN ELONGATED UPPER LOW CENTERED OFF THE
BAJA COAST. FOR OUR FORECAST AREA...ANTICIPATE CONTINUED DEVELOPMENT
THE REST OF THE AFTERNOON FOCUSING OVER OVER LA PAZ AND EASTERN
RIVERSIDE COUNTIES...INCLUDING JOSHUA TREE NATIONAL PARK...WHERE
CAPE IS BEST. FLASH FLOOD WATCH CONTINUES FOR JOSHUA TREE NATIONAL
PARK THROUGH 03Z. MODELS ALSO HOLD ON TO SOME BETTER CAPE OVER
HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA...THOUGH PWAT IS LOWER THERE. ONLY
SLIGHT CHANCES ELSEWHERE. SLOW DEVELOPING CONVECTION OVER NORTHWEST
MEXICO IS ANTICIPATED TO SEND DEBRIS CLOUDS...AND POSSIBLY SOME
EMBEDDED LIGHT SHOWERS...OVER OUR AREA LATE TONIGHT AND INTO THE
MORNING FRIDAY AND THUS HELD ON TO SOME LOW END POPS. MODELS SHOW
DECREASED LOWER LEVEL MOISTURE TO VARYING DEGREES ON FRIDAY AND THUS
LESS CAPE. HOWEVER...THERE WILL STILL BE ENOUGH LINGERING LOWER LEVEL
MOISTURE FOR A SLIGHT CHANCE AT MOST LOWER LEVEL LOCATIONS.

TROUGHING OFF THE WEST COAST BEGINS TO TAKE HOLD SATURDAY BEGINNING AN
EASTWARD RETREAT OF MOISTURE AND THUS A DOWNWARD TREND OF POPS FOR
THE WEEKEND. THE RIDGE REBUILDS EARLY NEXT WEEK BUT MODELS ARE
RELUCTANT TO BRING SIGNIFICANT MOISTURE BACK. JUST ENOUGH MOISTURE
HANGS ON OVER SOUTH- CENTRAL ARIZONA FOR LINGERING POPS OVER SOUTH-
CENTRAL ARIZONA MONDAY THROUGH THURSDAY BUT OVERALL A LOW GRADE
MONSOON SCENARIO.

&&

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

CHANCES FOR THUNDERSTORMS DURING THE REST OF THE NIGHTTIME HOURS IS
MINIMAL...NOT ZERO...BUT NOT HIGH ENOUGH TO MENTION ANY WEATHER OR
EVEN VCSH IN THE TAFS. WILL GO WITH FEW-SCT HIGH BASED CU AROUND 10K
AND SCT-BKN CIRRUS DECKS. WE ARE ONLY LOOKING AT SLIGHT CHANCES FOR
STORMS FRIDAY EVENING SO DO NOT EXPECT ANY WEATHER TO BE ADDED TO
THE TAFS FOR AT LEAST THE NEXT 18 HOURS. WINDS WILL BE ON THE LIGHT
SIDE AND FOLLOW NORMAL DIURNAL CONVECTIONS.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND
KBLH...

IT APPEARS THE THREAT FOR SHOWERS/STORMS OR EVEN STRONG OUTFLOWS IS
PRETTY MUCH OVER FOR THE REST OF TONIGHT...SO WE ARE LEFT WITH
MAINLY FEW-SCT MID AND UPPER LEVEL DEBRIS CLOUD DECKS THROUGH THE
AFTERNOON ON FRIDAY. WINDS WILL BE ON THE LIGHT SIDE THROUGH THE TAF
PERIOD....FAVORING THE SOUTH AT KBLH AND THE SOUTHEAST AT KIPL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
MONSOONAL MOISTURE WILL SLOWLY BEGIN TO THIN ACROSS THE AREA...FIRST
ACROSS THE WESTERN FIRE DISTRICTS AND EVENTUALLY INTO THE ENTIRE
LOWER DESERT ELEVATIONS AND REGION BY EARLY NEXT WEEK. THIS WILL
RELEGATE STORM CHANCES BACK TOWARDS THE HIGHER TERRAIN AND FURTHER
TO THE EAST ACROSS AZ. THE SLIGHTLY DRIER AIRMASS AND BUILDING UPPER
RIDGE HEIGHTS WILL LEND THEMSELVES TOWARD WARMER SFC CONDITIONS...AT
OR ABOVE SEASONAL NORMALS. WINDS WILL FOLLOW FAMILIAR WARM SEASON
PATTERNS.

&&

.SPOTTER INFORMATION STATEMENT...
SPOTTERS ARE ENCOURAGED TO REPORT CONDITIONS ACCORDING TO STANDARD
OPERATING PROCEDURES.

&&

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

&&

$$

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

DISCUSSION...CB
PREVIOUS DISCUSSION...AJ
AVIATION...CB
FIRE WEATHER...NOLTE


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.