859
FXUS65 KTWC 280925
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
225 AM MST SAT JUN 28 2025
SYNOPSIS...GENERALLY DRY AND WARMER THIS WEEKEND WITH ONLY SLIGHT
CHANCES FOR SHOWERS AND THUNDERSTORMS NEAR THE INT'L BORDER IN
COCHISE COUNTY. THE HOTTEST DAY WILL BE MONDAY WHEN AN EXTREME HEAT
WARNING IS IN EFFECT FOR PORTIONS OF SOUTHEAST ARIZONA. MONSOONAL
MOISTURE IS EXPECTED TO INCREASE NEXT WEEK WITH INCREASING
PRECIPITATION CHANCES, ESPECIALLY THE SECOND HALF OF THE WEEK
INCLUDING AROUND INDEPENDENCE DAY.
KEY MESSAGES
-TEMPERATURES WILL BE ON THE INCREASE THIS WEEKEND, PEAKING MONDAY
WITH HIGHS OF 108 TO 112 DEGREES IN THE DESERTS INCLUDING TUCSON AND
UPPER GILA RIVER VALLEY. AN EXTREME HEAT WARNING IS IN EFFECT MONDAY
FOR THESE LOCALES.
-GENERALLY DRY CONDITIONS THIS WEEKEND WITH ONLY A SLIGHT CHANCE OF
THUNDERSTORMS ALONG THE INT'L BORDER IN COCHISE COUNTY TODAY AND
SUNDAY.
-MONSOON 2025 WILL SWING INTO FULL GEAR NEXT WEEK. THE HEAT WILL BE
ON THE DOWNWARD TREND BY MIDWEEK AS MOISTURE WILL BE ON THE
INCREASE. INITIAL MONSOON STORM THREATS WILL BE FOCUSED MORE ON
GUSTY WINDS, BUT WILL QUICKLY TRANSITION MORE TOWARDS HEAVY RAIN AND
FLASH FLOODING THREATS AS THE WEEK PROGRESSES. THIS INCLUDES
INDEPENDENCE DAY.
DISCUSSION
MOSTLY CLEAR SKIES THIS MORNING FOR MOST OF THE
FORECAST AREA WITH THE EXCEPTION OF SOME LOCALES ALONG THE NM BORDER
WHERE PARTLY CLOUDY SKIES PREVAIL. THE MAIN STORY IN THE SHORT TERM
IS GOING TO BE ON THE HEAT AS HIGH PRESSURE ALOFT STRENGTHENS OVER
THE REGION OVER THE NEXT COUPLE OF DAYS. THIS WILL LEAD TO AN UPWARD
TREND IN TEMPERATURES WITH HIGHS PEAKING ON MONDAY BEFORE A COOLING
TREND THEREAFTER. HIGHS ON MONDAY WILL BE 108 TO 112 DEGREES FOR
PIMA, SE PINAL AND THE UPPER GILA RIVER VALLEY OF GRAHAM COUNTY AND
AN EXTREME HEAT WARNING REMAINS IN EFFECT FOR THESE LOCALES. WE
SHOULD NOTE THAT HIGHS ON SUNDAY DO APPROACH MAJOR HEATRISK LEVELS
BUT THE MAJOR HEATRISK COVERAGE REMAINS MORE ISOLATED SO NO HEAT
HEADLINES FOR SUNDAY AT THIS TIME. WITH THAT SAID, IT WILL STILL BE
QUITE HOT SO HEAT SAFETY REMAINS PARAMOUNT. WHILE THE HEAT WILL BE
THE MAIN FOCUS THROUGH MONDAY, MONSOONAL MOISTURE WILL BE CLOSE
ENOUGH FOR SOME BUILD-UPS AND A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS MAINLY ALONG THE INT'L BORDER TODAY AND SUNDAY. THESE
SLIGHT CHANCES EXPAND AS FAR NORTH AND WEST AS THE TUCSON METRO AREA
BY MONDAY EVENING AS MOISTURE LEVELS GRADUALLY NUDGE UPWARD AS THE
FLOW ALOFT BECOMES MORE EASTERLY. MAIN CONCERNS INITIALLY WILL BE
LIGHTNING WITH LITTLE RAINFALL AND GUSTY OUTFLOW WINDS CAPABLE OF
PRODUCING BLOWING DUST.
A MORE PRONOUNCED MOISTURE PUSH FROM THE EAST IS EXPECTED MONDAY
NIGHT AS OUTFLOW FROM NM PUSHES WESTWARD. THIS WILL BE THE BEGINNING
OF SETTING THE STAGE FOR A MORE ACTIVE MONSOON PERIOD FOR MID TO
LATE WEEK AS DEEP MOISTURE MOVES IN FROM THE SOUTH AND EAST. WHILE
TEMPERATURES WILL COOL OFF A FEW DEGREES ON TUESDAY AND PWAT VALUES
JUMP UP TO AROUND 1-1.2 INCHES FOR MUCH OF THE FORECAST AREA, THAT
WILL BE ENOUGH TO RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS FOR
MUCH OF THE FORECAST AREA TUESDAY AFTERNOON AND EVENING WITH
CONTINUED MAIN THREATS BEING GUSTY WINDS AND BLOWING DUST.
THE MORE SIGNIFICANT GULF OF CALIFORNIA AND SONORAN MOISTURE WILL
ARRIVE AS EARLY AS WEDNESDAY AND CONTINUE THROUGH INDEPENDENCE DAY.
WE SHOULD NOTE THAT SOME OF THIS DEEPER MOISTURE WILL BE AIDED BY A
LIKELY TROPICAL CYCLONE (INVEST 95E) WHICH THE NHC HAS A 90% CHANCE
OF DEVELOPMENT. THIS SYSTEM WILL BE MOVING NNW UP TOWARDS SOUTHERN
BAJA LATER IN THE WEEK AND WILL GIVE AN ASSIST IN PUSHING THE DEEPER
MOISTURE INTO OUR AREA. ENSEMBLES SHOW PWAT VALUES AVERAGING 1.2 TO
1.5 INCHES AND PERHAPS BRIEFLY HIGHER WEDNESDAY THROUGH FRIDAY AND
THIS TRANSLATES TO 120 TO 160 PERCENT OF NORMAL, WITH VALUES LIKELY
PEAKING THURSDAY. THIS PORTENDS TO AN ACTIVE PERIOD WEDNESDAY
THROUGH FRIDAY/INDEPENDENCE DAY. WHILE CONFIDENCE IS HIGH ON AN
ACTIVE PERIOD FOR THE FORECAST AREA WITH THUNDERSTORMS RESULTING IN
HEAVY RAIN AND FLASH FLOODING POTENTIAL, WE STILL HAVE LOW
CONFIDENCE ON THE DETAILS ESPECIALLY THIS FAR IN ADVANCE AND TIMING
SPECIFIC UP/DOWN PERIODS. MEANWHILE, WITH THE DEEP MOISTURE AND THE
MONSOON COMING IN FULL FORCE, TEMPERATURES WILL DROP TO BELOW NORMAL
LEVELS THURSDAY AND FRIDAY BUT THE HUMIDITY WILL BE QUITE
NOTICEABLE.
AVIATION
VALID THROUGH 29/12Z.
MAINLY SKC THIS MORNING, THEN SCT CLOUDS AT AROUND 10-13K FT AGL AFT
28/19Z MAINLY ALONG THE INT'L BORDER IN COCHISE COUNTY INCLUDING
KDUG AND ALONG THE AZ/NM BORDER. THERE IS A SLIGHT CHC OF ISOLD
-SHRA/-TSRA FOR KDUG FROM 28/19Z-29/04Z BUT OTHERWISE DRY CONDITIONS
FOR OTHER TERMINALS. ISOLD GUSTS UP TO 30-40 KTS NR ANY
-SHRA/-TSRA, OTHERWISE SFC WINDS NWLY AT 8-12 KTS THIS AFTERNOON AND
LESS THAN 10 KTS OTHERWISE. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.
FIRE WEATHER
WARMER TEMPERATURES AND GENERALLY DRY
CONDITIONS THIS WEEKEND. ISOLATED SHOWERS AND THUNDERSTORMS THIS
WEEKEND WILL MAINLY BE CONFINED ALONG THE INT'L BORDER IN COCHISE
COUNTY. MINIMUM RELATIVE HUMIDITIES FROM 10 TO 20 PERCENT THROUGH
MONDAY, THEN INCREASING TO 15 TO 30 PERCENT TUESDAY AND WEDNESDAY
AND 25 TO 50 PERCENT THURSDAY AND FRIDAY. WINDS GENERALLY LIGHT AND
UNDER 15 MPH WITH ISOLATED GUSTS UP TO 45 MPH UNDER ANY
THUNDERSTORMS. MOISTURE WILL BE ON THE INCREASE NEXT WEEK WITH
TYPICAL EARLY MONSOON SEASON THREATS OF GUSTY WINDS AND LIGHTNING
WITH LACK OF WETTING RAINS THROUGH TUESDAY. HOWEVER, WIDESPREAD RAIN
CHANCES DUE TO ADDITIONAL MOISTURE MOVE IN BY MID TO LATE WEEK WITH
THE THREATS TRANSITIONING TOWARDS HEAVY RAIN AND FLASH FLOODING.
TWC WATCHES/WARNINGS/ADVISORIES
EXTREME HEAT WARNING FROM 10 AM TO 8 PM MST MONDAY FOR AZZ501-502-
504>506-509.
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