743
FXUS65 KPSR 012018
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
118 PM MST SUN FEB 1 2026
KEY MESSAGES
- DRY CONDITIONS AND WELL ABOVE NORMAL TEMPERATURES WILL PREVAIL
THROUGH THE FIRST WEEK OF FEBRUARY.
- A PERIOD OF BREEZY NORTHEASTERLY TO EASTERLY WINDS WILL RETURN
DURING THE MIDDLE OF THE WORK WEEK.
SHORT TERM /TODAY THROUGH MONDAY/
MIDLEVEL WATER VAPOR IMAGERY SHOWS THE CENTER OF AN UNSEASONABLY
STRONG AREA OF HIGH PRESSURE JUST SOUTHWEST OF THE FOUR CORNERS
EARLY THIS AFTERNOON. H5 HEIGHTS OVER THE FORECAST AREA ARE STILL
ADVERTISED IN EXCESS OF THE 90TH PERCENTILE OF CFSR CLIMATOLOGY,
HOWEVER, NAEFS MEAN 850 MB TEMPERATURES ARE PERHAPS MORE
IMPRESSIVE AT AROUND 15-16C TODAY, WHICH IS IN EXCESS OF THE 99TH
PERCENTILE OVER PORTIONS OF THE COLORADO RIVER VALLEY AND CENTRAL
AZ. THE NOTABLY HIGH HEIGHTS AND WARM TEMPERATURES ALOFT, COUPLED
WITH EASTERLY DOWNSLOPE WINDS, WILL PROVIDE AN EXCELLENT SETUP FOR
LOWER DESERT HIGHS REACHING THE 80S IN MANY PLACES. IN FACT,
PHOENIX SKY HARBOR AIRPORT HAD ALREADY HIT 80F AS OF 12:15 PM MST,
AND IS LIKELY (70% CHANCE) TO AT LEAST TIE THE RECORD HIGH OF 83F
FOR TODAY'S DATE.
A WEAK UPPER LOW WEST OF BAJA CALIFORNIA, AND TO ITS NORTH/WEST,
A MERIDIONALLY ELONGATED SW-NE ORIENTED DEFORMATION ZONE ARE
APPARENT IN MIDLEVEL WATER VAPOR IMAGERY EARLY THIS AFTERNOON,
WHICH WILL INFLUENCE THE REGION AS HIGH PRESSURE CONTINUES TO
WEAKEN AND SHIFT EASTWARD MONDAY. AS THESE FEATURES APPROACH THE
REGION, THE MAIN SENSIBLE WEATHER IMPACTS WILL BE AN INCREASE HIGH
CLOUDS LATER TODAY INTO MONDAY, AND WEAKENING SURFACE PRESSURE
GRADIENTS RESULTING IN A RETURN TO LIGHT AND MOSTLY TERRAIN-DRIVEN
WINDS EARLY IN THE WORK WEEK. UNDER INCREASED HIGH CLOUDS AND
LOWER HEIGHTS ALOFT, TEMPERATURES WILL ALSO DROP OFF A BIT MONDAY,
BUT STILL GENERALLY REACH THE UPPER 70S TO NEAR 80F FOR THE
TYPICALLY WARMER LOWER DESERT LOCALES.
LONG TERM /TUESDAY THROUGH SATURDAY/
THE REST OF THE COMING WEEK SHOULD REMAIN QUIET AS ANOTHER REX
BLOCK DEVELOPS ACROSS THE WESTERN U.S. MIDWEEK. EVEN THOUGH THIS
BLOCKING SETUP WILL NOT LAST ALL THAT LONG (2-3 DAYS), THE RIDGE
IS FORECAST TO STRENGTHEN QUICKLY AND REACH NEAR CLIMATOLOGICAL
RECORD STRENGTH ACROSS WESTERN MONTANA, IDAHO, AND EASTERN OREGON.
H5 HEIGHTS FOR OUR REGION ARE LIKELY TO REACH 582DM AGAIN BY
WEDNESDAY, ADDING TO THE UNSEASONABLY WARM TEMPERATURES ALREADY IN
PLACE. HIGHS ARE EXPECTED TO REACH INTO THE LOWER 80S FOR MANY
LOWER DESERT LOCATIONS ON TUESDAY BEFORE PEAKING ON WEDNESDAY
BETWEEN 81-85 DEGREES. EASTERLY DOWNSLOPING WINDS SHOULD ALSO
START TO KICK IN BY WEDNESDAY POTENTIALLY PUSHING TEMPERATURES
WELL INTO THE 80S.
AN UPSTREAM PACIFIC TROUGH IS THEN SEEN MOVING TOWARD THE PACIFIC
NORTHWEST ON THURSDAY AND THIS WILL HELP TO BREAK DOWN THE REX
BLOCK. A WEAK CUT-OFF LOW THAT FORMS ON TUESDAY WEST OF BAJA
SHOULD ALSO SLOWLY MOVE NORTHEASTWARD INTO AT LEAST WESTERN
PORTIONS OF OUR REGION THURSDAY INTO FRIDAY, BUT GUIDANCE
CONTINUES TO SHOW LITTLE IF ANY WEATHER IMPACTS. MOISTURE
ADVECTION IS EXPECTED TO BE QUITE LOW AND ANY FORCING IS LIKELY
TO BE LIMITED, SO POPS REMAIN WELL UNDER 10% FOR THURSDAY AND
FRIDAY. THE ONLY REAL IMPACT IS LIKELY TO BE AN INCREASE IN
EASTERLY WINDS WITH SOME AREAS ACROSS EASTERN AND SOUTH-CENTRAL
ARIZONA POTENTIALLY SEEING GUSTS UP TO 30-35 MPH THURSDAY
MORNING. THE DECAYING CUT-OFF LOW MAY END UP EVENTUALLY GETTING
MOSTLY ABSORBED INTO THE INCOMING PACIFIC TROUGH, BUT THERE IS
STILL A GOOD AMOUNT OF UNCERTAINTY WITH THE EVENTUAL EVOLUTION OF
THE TWO SYSTEMS. FOR NOW, DUE TO THE LACK OF EXPECTED MOISTURE,
RAIN CHANCES REMAIN QUITE LOW THROUGH NEXT WEEKEND. THE BREAKDOWN
OF THE RIDGE SHOULD AT LEAST ALLOW FOR SOME COOLING LATE IN THE
WEEK WITH THE NBM SHOWING LOWER DESERT HIGHS MOSTLY FALLING BACK
INTO THE UPPER 70S.
AVIATION
UPDATED AT 1730Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO MAJOR AVIATION WEATHER CONCERNS EXPECTED THROUGHOUT THE TAF
PERIOD. EASTERLY WINDS WILL PREVAIL THROUGH AT LEAST THE NEXT 24
HOURS, WITH SOME PERIODIC GUSTS OF 15-20 KTS EARLY THIS AFTERNOON
AT KPHX AND KIWA. WINDS ARE EXPECTED TO RETURN TO THEIR TYPICAL
DIURNAL TENDENCIES TOMORROW, WITH A WESTERLY SHIFT ANTICIPATED
DURING THE LATE AFTERNOON HOURS. CLEAR SKIES THIS AFTERNOON WILL
GIVE WAY TO INCREASING HIGH CIRRUS CLOUD DECKS THIS EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER CONCERNS EXPECTED THROUGHOUT THE TAF PERIOD.
WINDS WILL FLUCTUATE BETWEEN THE NORTH AND WEST AT BOTH KIPL AND
KBLH WITH SPEEDS AOB 7 KTS. CLEAR SKIES LATE THIS MORNING WILL
GIVE WAY TO INCREASING HIGH CIRRUS CLOUD DECKS THIS AFTERNOON.
FIRE WEATHER
WELL ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS WILL PERSIST
OVER THE NEXT SEVERAL DAYS. HUMIDITIES WILL REMAIN QUITE LOW WITH
WITH AFTERNOON MINRHS COMMONLY BETWEEN 12-20% RANGE AREAWIDE.
OVERNIGHT RECOVERIES WILL REMAIN FAIR TO POOR WITH HUMIDITIES
GENERALLY TOPPING OUT IN A 35-55% RANGE. LIGHT AND MOSTLY
TERRAIN-DRIVEN WINDS WILL PREVAIL EARLY IN THE WORK WEEK. THE
WEATHER PATTERN WILL AGAIN SUPPORT BREEZY NORTHEASTERLY TO
EASTERLY WINDS MID TO LATE WEEK, WHICH COULD RESULT IN LOCALLY
ELEVATED FIRE WEATHER CONDITIONS OVER PROMINENT/EXPOSED HIGHER
TERRAIN AREAS AND RIDGETOPS OF SOUTHERN AZ.
CLIMATE
PHOENIX, AZ DAILY RECORD HIGH TEMPERATURES.
2/1 83 (2003)
2/2 82 (2025)
2/3 86 (2025)
2/4 86 (2025)
2/5 87 (1963)
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...WHITTOCK
LONG TERM...KUHLMAN
AVIATION...BERISLAVICH
FIRE WEATHER...WHITTOCK/KUHLMAN
CLIMATE...BENEDICT
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