Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 290535 AAA
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1035 PM MST THU MAY 28 2015

.UPDATE...UPDATED AVIATION DISCUSSION.

.SYNOPSIS...
HOT AND DRY WEATHER WILL ARRIVE INTO SOUTHEAST CALIFORNIA AND
SOUTHERN ARIZONA THIS WEEKEND WITH AFTERNOON HIGHS RANGING FROM
AROUND 102 TO 108 DEGREES FOR LOWER ELEVATION POPULATION CENTERS.
TEMPERATURES WILL COOL SOMEWHAT NEXT WEEK...COMING CLOSER TO THE
SEASONAL NORMAL HOWEVER WITH NO RAINFALL STILL ANYWHERE NEAR THE
AREA.

&&

.DISCUSSION... BUILDING HIGH PRESSURE IS KEEPING SKIES MAINLY CLEAR
ACROSS OUR CWA THIS EVENING...WITH TEMPERATURES ACROSS THE LOWER
DESERTS NOW IN THE UPPER 80 TO MID-90 RANGE AT THIS HOUR...ABOUT 3-5
DEGREES WARMER THAN WHAT WAS RECORDED AT THIS TIME YESTERDAY. THE
CLOSEST WEATHERMAKER TO OUR CWA IS A WEAK SHORTWAVE THAT IS BRINGING
SHOWERS AND THUNDERSTORM TO PARTS OF SOUTHERN UTAH...AND SOME MID
AND HIGH CLOUDINESS TO PARTS OF NORTHERN AZ. ONCE THIS SHORTWAVE
MOVES OFF TO THE EAST...INTO CO LATE TONIGHT AND FRIDAY...EVEN
STRONGER RIDGING...AND A WARMER AIRMASS IS EXPECTED TO PUSH
NORTHWARD ACROSS THE REGION. THIS ADDITIONAL WARMING IS EXPECTED TO
FINALLY PUSH MOST LOWER DESERT LOCATIONS INTO THE TRIPLE DIGITS ON
FRIDAY...WITH EVEN WARMER TEMPS OVER THE UPCOMING WEEKEND...WITH THE
LATEST BEST-PERFORMING GUIDANCE STILL PUSHING HIGHS INTO THE 105-
108F RANGE BY SUNDAY...A BIG CHANGE FROM WHAT WE SAW MOST OF THE
MONTH OF MAY SO FAR. AS FAR AS THE FORECAST FOR THE REMAINDER OF
TONIGHT...OTHER THAN SOME SLIGHTLY ADJUSTMENTS TO THE HOURLY
GRIDS...INHERITED FORECAST PRODUCTS ARE HOLDING UP WELL...AND NO
UPDATES ARE PLANNED.

&&

.PREVIOUS DISCUSSION... WEAK HEIGHT RISES WERE NOTED OVER THE REGION
PER 12Z SOUNDING DATA WITH H5 LEVELS NEAR 582DM...WITH THIS GENERAL
TREND CONTINUING THROUGH THE WEEKEND AS RIDGING BUILDS OVER THE
REGION. H5 HEIGHTS NEAR 588DM WILL BE COMMON THROUGHOUT THE FORECAST
AREA SATURDAY THROUGH MONDAY YIELDING THE WARMEST WEATHER OF THE
YEAR. 12Z DATA ALSO SHOWED 1C-2C OF WARMING IN THE H8-H7 LAYER
VERSUS WEDNESDAY MORNING...AND FURTHER HEATING OF THIS LAYER WILL
OCCUR INTO THE WEEKEND WITH H7 TEMPS PEAKING JUST ABOVE +10C AND H8
TEMPS IN A +25C TO +29C RANGE.

LITTLE IN THE WAY OF UPSTREAM THICK CIRRUS IS NOTED EITHER IN WV
IMAGERY NOR FORECAST BUFR SOUNDINGS...SUCH THAT NEAR FULL INSOLATION
WILL MATERIALIZE WITH LITTLE TO NO HINDRANCE TOWARDS A DEEP WELL
MIXED BOUNDARY LAYER. FORECAST TEMPERATURE SPREAD AMONG OPERATIONAL
AND ENSEMBLE MEMBERS IS EXTREMELY SMALL YIELDING VERY HIGH
CONFIDENCE THAT AFTERNOON HIGHS WILL REACH A 102F TO 108F RANGE FOR
LOWER ELEVATIONS. THIS IS NOT UNCOMMON FOR THIS TIME OF YEAR AND
WELL SHORT OF HEAT WARNINGS (AVERAGE FIRST 105F DAY FOR PHOENIX AND
YUMA IS MAY 23RD)...HOWEVER AFTER A PROLONGED PERIOD OF COOLER THAN
NORMAL WEATHER OVER THE REGION...A PRECAUTIONARY SPECIAL WEATHER
STATEMENT HAS BEEN ISSUED ALERTING PARTNERS AND CUSTOMERS OF THE HOT
WEEKEND.

NEXT WEEK...THE RIDGE ALOFT WILL EVENTUALLY GET BOOTED INTO THE
PLAINS AS A FAIRLY LARGE PACIFIC LOW APPROACHES THE WEST COAST LATE
SUNDAY. MODELS HAVE BEEN INSISTENT THAT A MOISTURE SEEP WILL ADVECT
WESTWARD TOWARDS FAR EASTERN ARIZONA SUNDAY AFTERNOON...PROVIDING
ENOUGH INSTABILITY FOR ISOLD THUNDERSTORMS AROUND THE WHITE
MOUNTAINS AND ALONG THE MOGOLLON RIM. CANNOT DISCOUNT AN ISOLATED
LIGHTNING STRIKE OVER THE SAN CARLOS REGION OF SRN GILA
COUNTY...HOWEVER THE CHANCE FOR RAINFALL REACHING THE GROUND IS
STILL MINIMAL. OTHERWISE...THE OVERALL CONSENSUS AMONG MODELS KEEPS
ALL OF THE ENERGY MAINLY OVER THE PACIFIC NORTHWEST AND NORTHERN
ROCKIES...THOUGH SHOULD HELP TO LOWER HEIGHTS SLIGHTLY OVER THE
SOUTHWEST STARTING MONDAY. THIS WILL HELP TO COOL THINGS OFF
SLIGHTLY GOING INTO THE MIDDLE OF NEXT WEEK WHERE HIGHS SHOULD DIP
BACK TO NEAR SEASONAL NORMALS.

&&

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

NO AVIATION CONCERNS THROUGH THE TAF PERIOD. A WEAK WEATHER
DISTURBANCE THAT IS NOW MOVING EASTWARD ACROSS NORTHERN AZ WILL
CONTINUE TO BRING SCT-BKN HIGH CIRRUS CLOUD LAYERS THROUGH THE
REMAINDER OF TONIGHT TO THE PHX AREA TAF SITES...WITH MAINLY CLEAR
SKIES TO RETURN ON FRIDAY...AS HIGH PRESSURE BUILDS OVER THE REGION.
MAINLY CLEAR SKIES TO PREVAIL AT THE SE CA TAF SITES THROUGH FRIDAY.
VERY WEAK SFC PRESSURE GRADIENTS TO KEEP WINDS ON THE LIGHT
SIDE...MAINLY AOB 8KTS...WITH EXTENDED PERIODS OF LIGHT AND VARIABLE
OR CALM WINDS LIKELY. TIMING OF THE TYPICAL DAILY WIND SHIFTS WILL
BE SOMEWHAT LATER THAN NORMAL...LIKE THE PAST FEW DAYS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
AS HIGH PRESSURE REMAINS SITUATED OVER THE DISTRICT...NORMAL TO
ABOVE NORMAL TEMPERATURES AND WIDESPREAD DRY WEATHER WILL STAY IN
PLACE OVER THE DISTRICT THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. A
FEW ISOLATED THUNDERSTORMS MAY FORM OVER THE WHITE MOUNTAINS AND THE
RIM SUNDAY AFTERNOON AND APPROACH SRN GILA COUNTY...HOWEVER CHANCES
FOR RAINFALL REACHING THE GROUND IS MINIMAL. AFTERNOON HIGH
TEMPERATURES WELL OVER 100F WILL BE COMMON AT LOWER ELEVATION
LOCATIONS YIELDING MINIMUM RELATIVE HUMIDITY VALUES BELOW 10 PERCENT
FOLLOWING FAIR OVERNIGHT RECOVERY. SFC WINDS WILL BE PRIMARILY WEAK
WITH THE USUAL AFTERNOON UPSLOPE GUSTINESS...HOWEVER A PERIOD OF
SOMEWHAT STRONGER WINDS WILL BE POSSIBLE AROUND THE MIDDLE OF NEXT
WEEK IN ASSOCIATION WITH A WEATHER DISTURBANCE MOVING NORTH OF THE
AREA.

&&

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

&&

$$

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

DISCUSSION...PERCHA/MO/KUHLMAN
AVIATION...PERCHA
FIRE WEATHER...MO


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