Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 081751
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1051 AM MST MON FEB 8 2016

.UPDATE...
UPDATED AVIATION SECTION.

&&

.SYNOPSIS...HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE
OVER THE SOUTHWESTERN UNITED STATES THROUGH THE COMING WORK WEEK.
THIS WILL RESULT IN A PROLONGED PERIOD OF SUNNY SKIES AND ABOVE
NORMAL TEMPERATURES ALONG WITH RELATIVELY LIGHT WINDS.

&&

.DISCUSSION...

AN ANOMALOUSLY STRONG HIGH PRESSURE SYSTEM BUILT OVER THE REGION
LAST NIGHT AND WILL REMAIN STATIONARY THIS WEEK. TEMPERATURES ON THE
LOWER DESERTS WILL WARM INTO THE 80S. HOWEVER...TODAY A DEVELOPING
SUBTROPICAL LIKE LOW PRESSURE SYSTEM WILL TRACK WELL SOUTH OF
AZ...MOVING EASTWARD ACROSS CENTRAL BAJA THIS AFTERNOON AND INTO
NORTH CENTRAL MEX SOUTH OF EL PASO ON TUE. A RESULTING NORTH/SOUTH
PRESSURE GRADIENT WILL CONTINUE ACROSS AZ FOR MUCH OF THE DAY WITH
NORTH AND NORTHEASTERLY BREEZES PARTICULARLY DOWN THE COLORADO RIVER
VALLEY. LIGHTER WINDS ARE FORECAST ON TUESDAY. OTHERWISE CURRENT DRY
FORECASTS LOOK OK. NO UPDATES PLANNED.

.PREVIOUS DISCUSSION...435 AM MST...

UPPER RIDGE HEIGHTS ENCOMPASS THE WESTERN MAJORITY OF THE NORTH
AMERICAN CONTINENT...SPANNING FAR TO THE NORTH INTO YUKON AND NW
TERRITORIES AS WELL AS AK. MEANWHILE...GENERAL AREA OF WEAK/LOWER
HEIGHTS CONTINUES TO PERSIST WEST OF AND OVER THE BAJA PENINSULA IN
CONJUNCTION WITH AN UL CIRC CENTER BEST OBSERVED VIA 400MB AND ABOVE
STREAMLINES. CLOUD COVER REMAINS CONFINED TO LOCATIONS JUST ALONG AND
SOUTH OF THE INTERNATIONAL BORDER AT TIME OF THIS WRITING...WITH
CLEAR SKIES AND MILD OVERNIGHT TEMPS OBSERVED ACROSS THE CWA.

FORECAST FOR THIS WORK WEEK WILL BE ONE OF PERSISTENCE...WITH
DAYTIME HIGHS PEAKING INTO THE 80S FOR MANY LOWER DESERT SITES AND
OVERALL DRY CONDITIONS. THE FORECAST AREA WILL GENERALLY REMAIN ON
THE EASTERN FLANK OF THE STRONG WEST COAST RIDGE...WITH 1000-500MB
THICKNESSES PEAKING INTO THE MID 560DM RANGE AND 850MB TEMPERATURES
RANGING 14 TO 16C EACH AFTERNOON WITH FAIRLY GOOD MIXING. THIS
ORIENTATION OF THE RIDGE WILL ALSO LEAD TO PROLONGED PERIODS OF
EASTERLY RIDGETOP/GAP WINDS OVER THE HIGHER TERRAIN NORTH/EAST OF
PHOENIX AND NORTHERLY WINDS DOWN THE CO RIVER VALLEY. FCST ML/UL WIND
STREAMLINES INDICATE THE RIDGE CIRC CENTER...CURRENTLY ANALYZED OVER
CA/OR...TO SINK SOUTHWARD THROUGH THE GREAT BASIN AND OVER SOCAL
DURING THE WEEK. THIS MOTION WILL SHUNT THE AFOREMENTIONED WEAK
ML/UL LOW ANCHORED SLIGHTLY OVER BAJA CA AND ASSOCIATED SUBTROPICAL
JET STREAM OFF TO OUR SE. WESTERN RIDGE HEIGHTS RANK IN THE 99TH
PERCENTILE TO MAX RANGE ON NAEFS PERCENTILE TABLES AND FORECAST HIGHS
REFLECT THE ANOMALOUS WARMTH AS WELL. A FEW RECORDS COULD BE AT
STAKE...MOSTLY IN PHOENIX...DURING THE WORK WEEK. PLEASE REFERENCE
THE CLIMATE SECTION BELOW FOR THE FCST VALUES AND RECORD DATA.

EXTENDED PERIOD...
DETERMINISTIC AND ENSEMBLE FCST SOLNS ARE IN EXCELLENT AGREEMENT
THROUGH THE LATE WEEKEND...CONTINUING OUR WARM AND DRY FORECAST UNDER
A WEST COAST RIDGE. RIDGE HEIGHTS DO BECOME MODIFIED DURING THE END
OF THE WEEK AS A PACIFIC SHORTWAVE RIDES UP INTO THE PAC NW.
PHASING AND SOLN DIFFERENCES BEGIN TO CROP UP BEGINNING MON
15/00Z /SUNDAY NIGHT/. DIFFERENCES LIE BETWEEN THE RESOLUTION AND
DEPTH OF SHORTWAVE MOVEMENT OVER THE NORTH CENTRAL CONUS AS WELL AS
CONVECTION OVER THE EQUATORIAL PACIFIC/EL NINO REGION. GFS/GEFS
SOLNS MAINTAIN TROPOSPHERIC WEAKNESS WILL BE STRONGER OVER THE
EASTERN PACIFIC SUCH THAT SHORTWAVE ENERGY WILL CUT OFF AND INTERACT
WITH ANOTHER EAST PAC/BAJA LOW AND BRING SOME MOISTURE INTO THE
REGION BY EARLY NEXT WEEK. MEANWHILE...EC/GEM/NAEFS SOLNS ARE NOT AS
ENTHUSIASTIC...MAINTAINING RIDGE HEIGHTS AND DRY CONDITIONS OVER THE
CWA. THE ONE UPSIDE AMONG THESE DIFFERENCES WILL BE A SLIGHT
LOWERING OF UL HEIGHTS...WITH A SUBTLE SCALING BACK THE WARMTH FROM
THE WORK WEEK FOR THE WEEKEND.

&&

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

EXPECT EAST AND NORTHEASTERLY SURFACE WINDS TO PREVAIL TODAY THROUGH
TUESDAY BEING AT THEIR STRONGEST MIDDAY AND EARLY AFTERNOON...GUSTS
15-20 KTS OCCASIONALLY...BUT OTHERWISE REMAIN BELOW 10 KTS AT OTHER
TIMES. ANTICIPATE SOME LIGHT AND VARIABLE CONDITIONS FROM TIME TO
TIME...ESPECIALLY LATE AFTERNOON AND EVENING. IN THE LOWER LEVELS
ABOVE THE SURFACE WINDS WILL BE SOLIDLY FROM THE EAST- NORTHEAST.
ALSO IN THAT LAYER...BUT WITHIN 1-2 KFT AGL...SPEEDS WILL STRENGTHEN
AGAIN TONIGHT TO ABOUT 20 KTS. EXPECT THIS SITUATION TO REMAIN BELOW
CRITERIA FOR MENTION OF LLWS IN THE TAFS. OTHERWISE...CLEAR SKIES
EXCEPT FOR SOME CIRRUS PASSING TO THE SOUTH.

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

EXPECT NORTHERLY SURFACE WINDS TO PREVAIL THROUGH TUESDAY BEING AT
THEIR STRONGEST THIS AFTERNOON OVER THE LOWER COLORADO RIVER VALLEY
WITH GUSTS TO 20 KTS. ANTICIPATE SOME LOCATIONS TO HAVE LIGHT AND
VARIABLE CONDITIONS FAVORING TYPICAL DRAINAGE PATTERNS OVERNIGHT AND
IN THE MORNING HOURS. OTHERWISE...CLEAR SKIES EXCEPT FOR SOME CIRRUS
PASSING TO THE SOUTH.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...

WEDNESDAY THROUGH SUNDAY...AN UNSEASONABLY STRONG HIGH PRESSURE
RIDGE WILL BUILD OVER THE WESTERN STATES DURING THE WEEK. THIS WILL
LEAD TO A PERSISTENT PERIOD OF WELL ABOVE NORMALS HIGH TEMPERATURES
...WITH READINGS PEAKING 10 TO 15 DEGREES ABOVE SEASONAL NORMALS.
MANY LOWER ELEVATION AND DESERT SITES WILL SEE A STRETCH OF DAYS
WITH HIGH TEMPERATURES WARMING PAST THE 80 DEGREE MARK. RH`S WILL
ALSO REMAIN ON THE DRIER AND BELOW NORMAL SIDE DURING THE WEEK WITH
MIN VALUES TYPICALLY IN THE LOW TO MIDDLE TEENS.

LOCALLY BREEZY CONDITIONS ALONG THE CO RIVER VALLEY ARE EXPECTED
EACH AFTERNOON. MORE NOTICEABLE EASTERLY WINDS WILL FLOW INTO THE
SOUTH-CENTRAL AZ DESERTS...WITH ELEVATED WINDS OVER RIDGETOPS AND
GAPS TO THE NORTH/EAST OF PHOENIX. WINDS ELSEWHERE WILL GENERALLY
FOLLOW TYPICAL DRAINAGE/SLOPE DRIVEN HEADINGS WITH LIGHT SPEEDS. BY
WEEKS END THE UPPER RIDGE WILL BEGIN TO SHIFT TO OUR EAST AS
TROUGHING ALIGNS ITSELF OVER THE WEST COAST AGAIN. SOME VERY SLIGHT
TEMPERATURE COOLING AND INCREASING CLOUDINESS ARE LIKELY OVER THE
WEEKEND.

&&

.CLIMATE...
                   PHOENIX         |        YUMA
             FCST | RECORD (YEAR)  | FCST | RECORD (YEAR)

MON FEB 8      83 | 86 (1970)      |   81 | 88 (1996)
TUE FEB 9      83 | 84 (1987)      |   83 | 90 (2015)
WED FEB 10     83 | 87 (1951)      |   83 | 93 (1951)
THU FEB 11     83 | 83 (1951)      |   84 | 86 (1971)

&&

.SPOTTER INFORMATION STATEMENT...
SPOTTERS ARE ENCOURAGED TO REPORT BASED ON STANDARD OPERATING
PROCEDURES.

&&

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

$$

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

DISCUSSION...VASQUEZ/NOLTE
AVIATION...AJ
FIRE WEATHER...NOLTE/CB


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