874
FXUS65 KTWC 210836
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
136 AM MST SAT DEC 21 2025
SYNOPSIS
DRY AND WARM WEATHER CONTINUES, WITH POTENTIALLY RECORD
BREAKING HIGH TEMPERATURES AT SOME LOCALES THROUGH TUESDAY. A
PACIFIC SYSTEM APPROACHES DURING THE PERIOD FROM THE MIDDLE TO LATE
NEXT WEEK, BRINGING SOME CHANCES (20-50%) OF RAIN SHOWERS AND
SLIGHTLY COOLER TEMPERATURES OVER THE HOLIDAYS.
KEY MESSAGES:
- ABNORMALLY WARM TEMPERATURES CONTINUE THROUGH MUCH OF THE FORECAST
PERIOD, WITH TEMPERATURES PEAKING MONDAY. TEMPERATURES SLOWLY
TRENDING DOWNWARD BEGINNING TUESDAY WITH ADDED CLOUD COVER, BUT
SHOULD REMAIN ABOVE NORMALS THROUGH AT LEAST THE END OF THE WEEK
(DEC 26).
- PATTERN CHANGE IS ARRIVING TUESDAY, PRIMARILY IN THE FORM OF CLOUD
COVER AND A FEW BREEZES, WITH A 30-50% CHANCE OF RAIN SHOWERS
TUESDAY NIGHT INTO WEDNESDAY.
- WE CONTINUE TO KEEP 20-40% RAIN CHANCES IN THE FORECAST FROM
CHRISTMAS EVE INTO NEXT WEEKEND, WITH THE HIGHEST RAIN CHANCES
FOCUSED FROM TUCSON NORTH AND WESTWARD. RAIN AMOUNTS WILL GENERALLY
REMAIN LESS THAN 0.25" DURING THIS PERIOD.
DISCUSSION
THE MAIN WEATHER STORY IN THE SHORT TERM IS THE
ABNORMALLY WARM DECEMBER TEMPERATURES AS STRONG HIGH PRESSURE ALOFT
REMAINS IN CONTROL OF OUR WEATHER. RECORD OR NEAR RECORD DAILY HIGH
TEMPERATURES WILL CONTINUE THROUGH TUESDAY WITH TEMPERATURES BROADLY
PEAKING ON MONDAY WITH HIGHS 15 TO 20 DEGREES ABOVE NORMAL.
A PATTERN CHANGE WILL BEGIN TO MANIFEST ITSELF ON TUESDAY AS THE
HIGH PRESSURE SLIDES OFF TO THE EAST, OPENING UP A LONGER FETCH OF
SOUTH TO SOUTHWESTERLY FLOW. MID AND HIGH LEVEL CLOUDS WILL BE ON
THE INCREASE WITH A FEW SOUTHWEST BREEZES.
FOR TUESDAY NIGHT INTO WEDNESDAY, MODELS ARE IN PRETTY GOOD
AGREEMENT THAT AN EMBEDDED TROPICAL ORIGIN DISTURBANCE IN THE
SOUTHWEST FLOW WILL MOVE ACROSS THE REGION WITH THE POTENTIAL (30-
50% CHANCE) FOR SOME LIGHT RAIN SHOWERS. PWAT ANOMALIES ARE QUITE
ELEVATED GIVEN THE WARM/MOIST AIRMASS FOR WINTER, THOUGH THE BULK OF
THE MOISTURE IS IN THE MID AND UPPER LEVELS. RAIN AMOUNTS WILL
GENERALLY BE NON IMPACTFUL AT LESS THAN 0.10 INCHES.
WHILE CONFIDENCE IS HIGH ON A MORE ACTIVE PATTERN WITH A STRONG
TROUGH AND UPPER LOW DEVELOPMENT NEAR/OFF THE WEST COAST, THE
DETAILS FOR OUR AREA ARE A BIT MURKY AS ADDITIONAL POTENTIAL
DISTURBANCES IN THE SOUTH TO SOUTHWEST FLOW POTENTIALLY IMPACT OUR
AREA CHRISTMAS EVE AND CHRISTMAS DAY, AND POTENTIALLY INTO THE
WEEKEND DEPENDING ON HOW THE TROUGH EJECTS EASTWARD. BROAD BRUSHED
20 TO 40 PERCENT POPS ARE REASONABLE DURING THIS PERIOD BUT THE
LIKELIHOOD IS THERE WILL BE A COUPLE OF PERIODS (RIGHT NOW LEANING
TOWARDS WED NIGHT/THURSDAY AND SATURDAY) WITH BETTER PRECIPITATION
CHANCES. THE BEST LIFT/DYNAMICS ESPECIALLY CHRISTMAS EVE AND
CHRISTMAS DAY WILL LIKELY CONTINUE TO BE FROM TUCSON NORTH AND
WESTWARD WITH QPF UP TO 0.10"-0.20" FOR THESE AREAS WITH LESSER
AMOUNTS SOUTH AND EAST. SNOW LEVELS WILL REMAIN ABOVE MOUNTAIN TOP
LEVELS THROUGH FRIDAY.
TEMPERATURES WILL REMAIN ABOVE NORMAL MID TO LATE WEEK BUT GRADUALLY
COOL TO LEVELS ABOUT 5 DEGREES ABOVE NORMAL NEXT WEEKEND.
AVIATION
VALID THROUGH 21/12Z.
GENERALLY LIGHT WINDS, REMAINING BELOW 10 KNOTS, WILL FOLLOW TYPICAL
DRAINAGE PATTERNS EXPECTED THROUGH THE VALID PERIOD. SKIES MOSTLY
CLEAR TO FEW AOA 25 KFT. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.
FIRE WEATHER
WARM AND DRY CONDITIONS CONTINUE THROUGH THE DAY
TUESDAY WITH HIGHS 15 TO 20 DEGREES ABOVE NORMAL, WITH GRADUAL
COOLING THEREAFTER. MINIMUM RELATIVE HUMIDITY VALUES OF 12-22
PERCENT EACH DAY THROUGH TUESDAY. 20-FOOT WINDS LESS THAN 15 MPH AND
TERRAIN DRIVEN THROUGH MONDAY, THEN BECOMING MORE SOUTHWESTERLY WITH
A FEW HIGHER GUSTS AROUND 20 MPH TUESDAY AND WEDNESDAY. A PACIFIC
SYSTEM APPROACHES THE MIDDLE OF NEXT WEEK WITH BROAD BRUSHED 20 TO
50 PERCENT SHOWER CHANCES TUESDAY NIGHT INTO SATURDAY WITH
INCREASING MINIMUM HUMIDITY VALUES TO 30 TO 50 PERCENT.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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