446
FXUS65 KTWC 200835
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
135 AM MST SAT DEC 20 2025
SYNOPSIS
DRY AND WARM WEATHER CONTINUES, WITH POTENTIALLY RECORD
BREAKING HIGH TEMPERATURES AT SOME LOCALES INTO EARLY NEXT WEEK. A
PACIFIC SYSTEM APPROACHES DURING THE PERIOD FROM THE MIDDLE TO LATE
NEXT WEEK, WITH THE CHANCE OF SHOWERS AND SLIGHTLY COOLER
TEMPERATURES.
DISCUSSION
NO CHANGE TO THE OVERALL FORECAST IN THE SHORT TERM AS
OUR PATTERN IS DOMINATED BY STRONG HIGH PRESSURE ALOFT CENTERED TO
OUR SOUTH. THIS PATTERN WILL CONTINUE TO RESULT IN WELL ABOVE NORMAL
TEMPERATURES, WITH HIGHS RUNNING 15 TO 20 DEGREES ABOVE NORMAL
THROUGH MONDAY AND A CONTINUATION OF DAILY NEAR RECORD TO RECORD
HIGH TEMPERATURES.
THE PATTERN WILL START TO CHANGE ON TUESDAY AS THE RIDGE SLIDES OFF
TO OUR EAST. THIS WILL RESULT IN PROLONGED SOUTH-SOUTHWEST FLOW
ALOFT BETWEEN THE HIGH TO OUR EAST AND STRONG TROUGING ALONG THE
WEST COAST. ENSEMBLES ARE IN GOOD AGREEMENT IN BRINGING A
SUBTROPICAL DISTURBANCE UP THROUGH THE AREA TUESDAY NIGHT INTO
WEDNESDAY. MUCH ABOVE NORMAL MOISTURE LEVELS IN THE MID AND UPPER
LEVELS WILL MOVE IN DURING THIS TIMEFRAME WITH CONSIDERABLE HIGH
LEVEL CLOUDS DURING THE DAY TUESDAY. TEMPERATURES WILL STILL REMAIN
ABOUT 15 DEGREES ABOVE NORMAL TUESDAY. EVEN WITH CONSIDERABLE
MOISTURE IN THE MID AND UPPER LEVELS, THIS INITIAL SYSTEM DOESN'T
LOOK TOO IMPACTFUL TUESDAY NIGHT INTO WEDNESDAY WITH BROAD BRUSHED
POPS IN THE 10 TO 30 PERCENT RANGE AND ASSOCIATED QPF MAINLY LESS
THAN 0.10". SNOW LEVELS WOULD BE AT OR ABOVE MOUNTAIN TOPS.
A BIT MORE UNCERTAINTY STARTING CHRISTMAS DAY AS THE TROUGHINESS
REMAINS ACROSS THE WEST COAST WITH ENSEMBLES SHOWING ANOTHER
DISTURBANCE ON THE SOUTHEAST FLANK OF THE BROADER TROUGH GENERALLY
PUSHING THROUGH SOUTHERN CALIFORNIA/WESTERN ARIZONA. IT STILL LOOKS
LIKE THE MAIN IMPACTS WILL STAY TO OUR NORTH AND WEST BUT CERTAINLY
THE POTENTIAL FOR MORE SHOWERS ON CHRISTMAS DAY AND EVEN INTO
FRIDAY. THEREAFTER, THE POTENTIAL FOR MORE ACTIVE WEATHER CONTINUES
NEXT WEEKEND AS THE MAIN AREA OF TROUGHINESS TRIES TO SWING EAST.
MEANWHILE, TEMPERATURES WILL GRADUALLY COOL WEDNESDAY THROUGH FRIDAY
BUT STILL REMAIN ABOVE NORMAL.
AVIATION
VALID THROUGH 21/12Z.
MAINLY SKC-SCT CLOUDS AOA 20K FT AGL THROUGH THE VALID PERIOD.
SURFACE WINDS UNDER 10 KTS AND TERRAIN DRIVEN. AVIATION DISCUSSION
NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
WARM AND DRY CONDITIONS CONTINUE INTO EARLY NEXT
WEEK. HIGHS 15 TO 20 DEGREES ABOVE NORMAL THROUGH MONDAY WITH
GRADUAL COOLING MID TO LATE NEXT WEEK. MINIMUM RELATIVE HUMIDITY
VALUES OF 12-22 PERCENT EACH DAY THROUGH EARLY NEXT WEEK. 20-FOOT
WINDS LESS THAN 15 MPH AND TERRAIN DRIVEN. A PACIFIC SYSTEM
APPROACHES THE MIDDLE OF NEXT WEEK WITH BROAD BRUSHED 10 TO 30
PERCENT SHOWER CHANCES TUESDAY NIGHT INTO FRIDAY WITH INCREASING
HUMIDITY VALUES TO 25 TO 40 PERCENT.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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