289
FXUS65 KTWC 202130
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 PM MST THU NOV 20 2025
SYNOPSIS
AN ACTIVE PATTERN CONTINUES THROUGH THIS WEEKEND AS A SECOND
SYSTEM IS EXPECTED TO ARRIVE LATE FRIDAY THROUGH SUNDAY. CHANCES
FOR PRECIPITATION HOLD OFF FOR MUCH OF SOUTHEASTERN ARIZONA UNTIL
SATURDAY AFTERNOON AND EVENING, THOUGH SHOWERS MAY BEGIN TO MOVE
INTO WESTERN PIMA WESTERN TO CENTRAL PORTIONS OF ARIZONA ON
FRIDAY. TEMPERATURES REMAIN WELL BELOW NORMAL WITH THE FIRST
WIDESPREAD FREEZE EXPECTED FRIDAY MORNING, MAINLY IN THE VALLEYS
SOUTH AND EAST OF TUCSON.
DISCUSSION
BROAD TROUGHING WITH MULTIPLE EMBEDDED SHORTWAVES CONTINUED OVER
THE SOUTHWESTERN UNITED STATES THIS AFTERNOON, WITH THE INITIAL
WAVE EXITING SOUTHEASTERN ARIZONA TO THE EAST. LOOKING UPSTREAM
ANOTHER WAVE WAS DIGGING SOUTH OVER THE SOUTHWEST COAST OF
CALIFORNIA. IN-BETWEEN THESE WAVES A BRIEF BREAK IN PRECIPITATION
CHANCES IS EXPECTED BEFORE THE SECOND WAVE ARRIVES, WITH
UNSEASONABLY COLD TEMPERATURES CONTINUING.
FRIDAY MORNING IN THE WAKE OF THE EXITING SYSTEM, SUB-FREEZING
MORNING LOWS LOOK LIKELY ACROSS VALLEYS OF SANTA CRUZ, COCHISE,
AND GRAHAM COUNTIES. A FREEZE WARNING REMAINS IN PLACE FOR THESE
AREAS. A HARD FREEZE IS WELL WITHIN THE RANGE OF POSSIBILITIES AS
NBM PROBABILITIES OF LOWS BELOW 28 DEGREES RANGE FROM 60 TO 90
PERCENT ACROSS THE SULPHUR SPRINGS VALLEY.
THE SECOND UPPER LEVEL WAVE IS EXPECTED TO DROP SOUTH OVER THE
EASTERN PACIFIC, WEST OF BAJA, THROUGH FRIDAY AND BECOME
POSITIVELY TILTED AND CLOSED. BOTH THE POSITIVELY TILTED
ORIENTATION AND CLOSED OFF PROCESS SIGNAL A SLOWING TREND IN THE
EVENTUAL ARRIVAL OF THIS LOW, AND RECENT MODEL TRENDS HAVE PLAYED
OUT AS SUCH. CURRENT FORECAST BRINGS RAIN CHANCES INTO WESTERN
PIMA COUNTY AS EARLY AS FRIDAY AFTERNOON THEN SPREADS EAST ON
SATURDAY...HOWEVER CAN'T RULE OUT THE TIMING NUDGING A BIT SLOWER
IN THE NEXT DAY. THE MAIN BRUNT OF THE SYSTEM IS CURRENTLY
FORECAST TO SWING THROUGH LATE SATURDAY THROUGH EARLY SUNDAY WITH
ANOTHER ROUND OF VALLEY RAIN AND HIGH ELEVATION MOUNTAIN SNOW
SHOWERS EXPECTED. SNOW LEVELS SHOULD REMAIN ABOVE 7500 FEET WITH
2-5 INCHES OF SNOW ACCUMULATION LIKELY ATOP MOUNTAINS. LOOKING AT
TEMPERATURES THERE SHOULD BE A MINOR WARM-UP ON SATURDAY BEFORE
THE SECOND WEEKEND SYSTEM ARRIVES, ESPECIALLY IF IT DELAYS, THEN
WELL BELOW NORMAL TEMPERATURES ARE EXPECTED SUNDAY AND MONDAY.
SUB-FREEZING TEMPERATURES WILL RETURN IN VALLEYS EAST AND SOUTH
OF TUCSON MONDAY MORNING. RIDGING THEN TAKES OVER EARLY TO THE
MIDDLE OF NEXT WEEK BRINGING TEMPERATURES BACK TO NORMAL.
AVIATION
VALID THROUGH 22/00Z.
SCT-BKN CEILINGS AT 4K-7K FEET BECOMING FEW-SCT THROUGH THIS
EVENING. ISOLATED SHOWERS DIMINISH THIS EVENING, LINGER LONGEST
NEAR KSAD AND NORTHEASTWARD. WINDS BECOME LIGHT AND TERRAIN DRIVEN
AFTER 21/03Z. CLOUDS AOA 15K FEET INCREASE FROM THE WEST AFTER
21/06Z. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
BELOW NORMAL TEMPERATURES CONTINUE THROUGH THE WEEKEND WITH
MINIMUM RELATIVE HUMIDITIES ABOVE 30 PERCENT, WITH A MINOR DIP TO
25 PERCENT IN THE VALLEYS ON FRIDAY AS SOUTHEASTERN ARIZONA WILL
SIT BETWEEN TWO SYSTEMS. THE SECOND SYSTEM ARRIVES LATE FRIDAY
THROUGH SATURDAY BRINGING ANOTHER ROUND OF SHOWERS AND HIGH
ELEVATION MOUNTAIN SNOW. CHANCES FOR SHOWERS REMAIN WEST OF TUCSON
THROUGH SATURDAY MORNING, THEN SPREAD EAST SATURDAY AFTERNOON AND
EVENING LINGERING SUNDAY. TEMPERATURES RISE TO NEAR NORMAL BY THE
MIDDLE OF NEXT WEEK.
TWC WATCHES/WARNINGS/ADVISORIES
FREEZE WARNING FROM 2 AM TO 9 AM MST FRIDAY FOR AZZ503-507>509.
PUBLIC...EDWARDS
AVIATION...EDWARDS
FIRE WEATHER....EDWARDS
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