Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 272018
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
118 PM MST WED AUG 27 2014

.SYNOPSIS...
DRIER AIR WILL CONTINUE TO MOVE INTO THE REGION TONIGHT...USHERING
IN A DRIER AND WARMER PATTERN ACROSS THE DESERT SOUTHWEST THROUGH AT
LEAST EARLY NEXT WEEK. HIGH TEMPERATURES WILL RETURN TO NEAR NORMAL
VALUES BY THURSDAY...PEAKING BETWEEN 105 AND 110 FRIDAY AND
SATURDAY...BEFORE RETREATING SLIGHTLY NEXT WEEK.

&&

.DISCUSSION...
EARLY AFTERNOON WATER VAPOR IMAGERY CONTINUES TO REVEAL AN UPPER LOW
OVER UTAH WITH A VERY WEAK SHORTWAVE TROUGH MOVING THROUGH EASTERN
ARIZONA. RADAR AND SATELLITE IMAGERY INDICATE THAT A FEW CU AND EVEN
A FEW SHOWERS HAVE DEVELOPED IN THE HIGHER TERRAIN LOCATIONS EAST OF
PHOENIX...BUT SKIES WERE CLEAR TO THE WEST OF MARICOPA COUNTY. TEMPS
AS OF 20Z WERE GENERALLY IN THE UPPER 90S ACROSS THE LOWER DESERTS
ALTHOUGH THERE REMAINED QUITE A DEWPOINT DISCONTINUITY FROM YUMA
/DEWPOINTS IN THE LOW 40S/ TO PHOENIX /DEWPOINTS IN THE LOWER 60S/.

DRY ADVECTION IN THE LOW LEVELS AND WARM ADVECTION ALOFT WILL
CONTINUE ACROSS THE AREA THIS EVENING WHICH WILL SIGNIFICANTLY LIMIT
THE AMOUNT OF CONVECTION ACROSS THE AREA. THE HIGHEST LIKELIHOOD OF
SHOWERS REMAINS IN THE MOUNTAINS EAST OF PHOENIX...BUT THESE CHANCES
WILL DIMINISH QUICKLY WITH THE LOSS OF DAYTIME HEATING AFTER 02Z. I
WILL MAINTAIN 10-20 POPS EAST OF PHOENIX THROUGH EARLY EVENING WITH
ZERO POPS OVERNIGHT AS STRONG SUBSIDENCE TAKES HOLD.

THE FORECAST FOR THURSDAY THROUGH THE WEEKEND REMAINS LARGELY
UNCHANGED...DRY WEATHER WITH INCREASING TEMPERATURES. POPS WERE
ALREADY ZEROED OUT DURING THIS PERIOD AND WITH WARM H5 TEMPERATURES
AROUND -3C...BL MIXING RATIOS AROUND 4-5 G/KG AND NO MLCAPE TO SPEAK
OF...WILL BE DIFFICULT TO GET ANY CU LET ALONE STORMS.
CONSEQUENTLY...TEMPERATURES WILL BE ON THE RISE EVENTUALLY MAXING
OUT BETWEEN 105-110 ACROSS THE WARMEST DESERT LOCATIONS.

THE UPPER RIDGE WILL BEGIN TO BREAK DOWN ON SATURDAY AS A TROUGH
MOVES INTO THE PACIFIC NORTHWEST. MODELS ARE IN EXCELLENT AGREEMENT
THIS TROUGH WILL FLATTEN THE RIDGE TO OUR SOUTHWEST...BUT KEEP US
UNDER A WESTERLY TO NORTHWESTERLY DRY UPPER LEVEL FLOW INTO NEXT
MONDAY. HIGHS SHOULD START TO TREND DOWNWARD STARTING SUNDAY AS THE
TROUGH TO OUR NORTH SLOWLY KNOCKS DOWN OUR UPPER HEIGHTS. SOME MODEL
DIFFERENCES ARE SHOWN NEAR THE END OF THE FORECAST PERIOD FOR NEXT
TUESDAY AND WEDNESDAY AS THE EUROPEAN BEGINS TO REBUILD THE
SUBTROPICAL HIGH TO OUR SOUTHEAST AND POSSIBLY ALLOWS FOR SOME
MINIMAL MOISTURE RETURN UNDER WEAK SOUTHEASTERLY FLOW. THE GFS KEEPS
THE DRIER WESTERLY FLOW ALOFT UNDER A WEAKER SUB-TROPICAL HIGH
CENTERED STILL TO OUR SOUTHWEST. TO ACCOUNT FOR THE POTENTIAL RETURN
IN MONSOONAL MOISTURE...HAVE INTRODUCED AT LEAST SOME LOW END SLIGHT
CHANCE POPS FOR TUESDAY AND WEDNESDAY ACROSS THE HIGHER TERRAIN IN
GILA COUNTY.

&&

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

STRONG SUBSIDENCE BEHIND A DEPARTING TROUGH WILL TAKE HOLD ACROSS
THE AREA TONIGHT. AS A RESULT...WEATHER CONCERNS ARE MINIMAL THROUGH
THURSDAY. MOSTLY CLEAR SKIES AND LIGHT DIURNAL WINDS ARE FORECAST AT
ALL SITES.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
NORTHWEST FLOW AND DRY CONDITIONS WILL PREVAIL ACROSS THE AREA
THROUGH EARLY NEXT WEEK...WITH NO STORM CHANCES EXPECTED ACROSS THE
REGION. MOISTURE WILL RETURN TO FAR EASTERN ARIZONA BY THE MIDDLE OF
NEXT WEEK BUT UNTIL THEN...THERE WILL BE A BREAK IN THE TYPICAL
MONSOON PATTERN. AFTERNOON HUMIDITIES WILL DROP INTO THE TEENS EACH
DAY WITH FAIR OVERNIGHT RECOVERY EXPECTED. RECOVERIES WILL SLOWLY
IMPROVE AS MOISTURE INCREASES NEXT WEEK. WINDS WILL BE LIGHT THROUGH
NEXT WEEK WITH NO MAJOR WIND EVENTS EXPECTED.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...LEINS/KUHLMAN
AVIATION...LEINS
FIRE WEATHER...LEINS





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