Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 040348
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
850 PM MST TUE MAY 3 2016

.SYNOPSIS...
TEMPERATURES WILL QUICKLY WARM TODAY AND PEAK WEDNESDAY UNDER HIGH
PRESSURE. SOME LOWER DESERTS WILL APPROACH TRIPLE DIGITS. THE HEAT
WILL NOT LAST LONG AS ANOTHER STORM SYSTEM ROLLS IN FROM THE PACIFIC.
WINDS WILL INCREASE WEDNESDAY AND BE STRONGEST THURSDAY LEADING TO
AREAS OF BLOWING DUST. FRIDAY INTO THE WEEKEND WILL FEATURE BELOW
NORMAL TEMPERATURES...VARIOUS CLOUD COVER...AND MODEST CHANCES FOR
RAIN.

&&

.DISCUSSION...
UPPER RIDGE CONTINUED TO BUILD ACROSS THE DESERT SOUTHWEST THIS
AFTERNOON AND EVENING...AHEAD OF A LARGE UPPER LOW TAKING SHAPE JUST
OFF THE WEST COAST. 500MB HEIGHTS HAVE CLIMBED JUST ABOVE 580DM OVER
THE SRN DESERTS AND UNDER FULL SUNSHINE TODAY HIGH TEMPS CLIMBED
INTO THE MID 90S OVER THE WARMER LOWER DESERTS. PHOENIX TOPPED OUT
AT 94 DEGREES...COMPARED TO THE NORMAL HIGH OF 91. IR IMAGERY AT 8
PM SHOWED JUST A FEW THIN HIGH CLOUDS SPREADING INTO SERN CA
OTHERWISE SKIES WERE CLEAR...AND WINDS WERE LIGHT. FOR THE REST OF
TONIGHT EXPECT GENLY CLEAR SKIES AND LIGHT DIURNAL WINDS. IT LOOKS
TO BE A PRETTY GOOD BET THAT PHOENIX WILL REACH THE FIRST 100 DEGREE
MARK OF THE YEAR TOMORROW...ESPECIALLY GIVEN THAT WE SHOULD SEE
MOSTLY SUNNY SKIES AND HAVE BREEZY SOUTH WINDS DURING THE AFTERNOON
WHICH OFTEN HELP THE TEMPERATURE AT SKY HARBOR TO SPIKE UPWARDS A
FEW DEGREES. WE SHALL SEE. NO UPDATES NEEDED TO THE FORECAST AT THIS
TIME.

.PREVIOUS DISCUSSION...
CLEAR AND WARM ACROSS THE NWS PHOENIX FORECAST AREA THIS AFTERNOON.
TEMPERATURES AT 2 PM WERE GENERALLY ABOUT 5 DEGREES WARMER THAN THIS
TIME YESTERDAY. DETERMINISTIC/ENSEMBLE MODELS REMAIN IN GOOD
AGREEMENT ON THE FORECAST THROUGH THE NEXT FIVE DAYS.

FOR WEDNESDAY...RIDGE OVERHEAD WILL BE MIGRATING WEST AS THE LARGE
UPSTREAM CLOSED LOW CONTINUES TO TAKE SHAPE AND MOVE INLAND. THE
RESULT WILL BE A SOMEWHAT BREEZY DAY BUT MORE NOTABLY VERY WARM
TEMPERATURES. WE ARE STILL FORECASTING PHOENIX TO HIT ITS FIRST 100
DEGREE DAY...WHICH DURING THE 1981-2010 PERIOD HAPPENS ON AVERAGE BY
MAY 2. ALL THE MODEL DATA IS TIGHTLY CLUSTERED IN THE 99-101 RANGE
THOUGH MIXING OUT BOUNDARY LAYER TEMPERATURES WOULD INDICATE THE
LOWER END OF THE RANGE MAY BE MORE LIKELY. IF WE DO END UP MISSING
IT TOMORROW IT WILL LIKELY BE A WHILE BEFORE WE HAVE ANOTHER CHANCE
AT IT. WINDS ARE NOT LOOKING QUITE AS STRONG FOR TOMORROW/WEDNESDAY
AS ORIGINALLY THOUGHT SO WE DID REMOVE THE BLOWING DUST FROM THE
FORECAST.

THE SYSTEM CONTINUES TO MOVE IN THURSDAY AND WIND FIELDS INCREASE IN
RESPONSE. WHILE WE ARE STILL A BIT BELOW WI.Y CRITERIA IT WILL FEEL
LIKE A WINDY DAY FOR MOST AREAS AND WE STILL EXPECT BLOWING DUST TO
BE AN ISSUE. WE MAY NEED A WI.Y AND/OR BD.Y FOR THIS EVENT.

THE LOW WILL MOVE ONSHORE FRIDAY. WHILE IVT VALUES AREN/T FORECAST TO
BE VERY HIGH BY THE GEFS /LIKELY REMAINING BELOW 250 KG/M/S BUT ABOVE
150/ THERE WILL BE ENOUGH TO EVENTUALLY GET SOME LIGHT TO MODERATE
SHOWERS GOING. THE EC IS A BIT FASTER SHOWING THE MOISTURE FLUX
INCREASING ENOUGH DURING THE DAY FRIDAY TO GET SHOWERS GOING BUT THE
GEFS AND SREF REALLY HOLD OFF UNTIL FRIDAY NIGHT. PREFER THE SLIGHTLY
SLOWER AND MORE SUPPORTED OPTION. ONCE SHOWERS GET GOING FRIDAY NIGHT
A GENERALLY SOUTHWEST FLOW MAY KEEP SOME UPSLOPE SHOWER ACTIVITY
GOING INTO SATURDAY AND MAYBE SUNDAY. BURF SOUNDINGS SUPPORT SOME
MINOR INSTABILITY WITH THIS SYSTEM SO THUNDERSTORMS ARE NOT OUT OF
THE QUESTION.

THE SYSTEM BECOMES MORE DIFFUSE AND BEGINS TO SWIRL TO THE NORTHEAST
SUNDAY WITH A BROAD RIDGE BUILDING IN MONDAY. TEMPERATURES WILL BEGIN
TO WARM TOWARD SEASONAL NORMALS WITH CLEARING SKY.

&&

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

HIGH PRESSURE ALOFT WILL LEAD TO CONTINUED GENLY CLEAR SKIES ALONG
WITH LIGHT DIURNAL WINDS ACROSS THE DESERTS...ESPECIALLY THE GREATER
PHOENIX AREA...FOR THE REST OF TONIGHT AND INTO THE DAY ON
WEDNESDAY. WE SHOULD SEE WINDS INCREASING FROM THE SOUTHEAST IN THE
PHOENIX AREA DURING THE MORNING TOMORROW...BECOMING MOSTLY SOUTHERLY
AND LOCALLY BREEZY WELL INTO THE AFTERNOON. GUSTY SOUTH WINDS ARE
ALSO EXPECTED AT KBLH FROM 18Z ONWARDS ON WEDNESDAY. OVERALL NO
AVIATION IMPACTS AT ANY TERMINAL FOR THE REST OF TONIGHT AND INTO
THE MORNING TOMORROW. WINDS SHOULD NOT BE STRONG ENOUGH WED
AFTERNOON TO CAUSE BLOWING DUST ISSUES AT THE TAF SITES BUT THIS
MAY CHANGE ON THURSDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...

...FIRE WEATHER WATCH THURSDAY AFTERNOON AND EVENING ACROSS
SOUTHWEST AND SOUTH CENTRAL ARIZONA...

FRIDAY THROUGH TUESDAY...
WITH A LARGE COOL PACIFIC LOW PRESSURE SYSTEM IN PLACE EXPECT COOLER
AND WELL BELOW NORMAL AFTERNOON HIGH TEMPERATURES TROUGH SUNDAY AND
MODERATELY BELOW NORMAL HIGHS BY MONDAY. THE RELATIVELY MOIST AIRMASS
WILL SUPPORT MINIMUM RELATIVE HUMIDITIES IN THE 20 TO 25 PERCENT
RANGE THROUGH SATURDAY. BREEZY TO OCCASIONALLY WINDY SOUTHWEST WINDS
ARE EXPECTED TO DEVELOP FRIDAY AFTERNOON WITH GUSTS IN THE 15 TO 25
MPH RANGE IN THE LOWER DESERTS AND 20 TO 30 MPH IN THE TONTO
FOOTHILLS AND SOUTHERN GILA COUNTY AND SOUTHEAST CA. WINDS WILL
DECREASE TO THE 10 TO 15 MPH RANGE SATURDAY THROUGH TUESDAY
AFTERNOON. IN ADDITION...A SLIGHT CHANCE OF AFTERNOON SHOWERS AND
ISOLATED THUNDERSTORMS ARE POSSIBLE FROM LATE AFTERNOON AND EVENING
ON FRIDAY THROUGH SATURDAY.

&&

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
     EVENING FOR AZZ132-133.

CA...NONE.
&&

$$

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

DISCUSSION...CB
PREVIOUS DISCUSSION...INIGUEZ
AVIATION...CB
FIRE WEATHER...SAWTELLE


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