364
FXUS65 KTWC 220848
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
149 AM MST MON DEC 22 2025
SYNOPSIS
DRY AND WARM WEATHER CONTINUES THROUGH TUESDAY, WITH
THE POTENTIAL FOR RECORD HIGH TEMPERATURES AT A FEW LOCATIONS. AN
APPROACHING PACIFIC STORM SYNTO THE UPCOMING WEEKEND, CONFIDENCE
STARTS TO LOWER ON THE EASTWARD PROGRESSION OF THE TROUGH WITH VERY
SIGNIFICANT DIFFERENCES BY AROUND SUNDAY WITH THE GFS/GEFS
MAINTAINING A STRONGER UPPER LOW TO OUR WEST COMPARED TO THE
ECMWF/EPS/CMCE WHICH WEAKEN THE SYSTEM WITH RIDGING EVENTUALLY
TAKING OVER. GIVEN THIS UNCERTAINTY, THE NBM POPS (~5%-20%) FRIDAY
THROUGH SUNDAY ARE REASONABLE. TEMPERATURES THIS WEEKEND WILL COOL
TO ABOUT 3 TO 6 DEGREES ABOVE NORMAL. STEM WILL RESULT IN A CHANCE
OF RAIN SHOWERS TUESDAY NIGHT INTO NEXT WEEKEND. THIS SYSTEM WILL
BRING COOLER BUT STILL ABOVE NORMAL HIGH TEMPERATURES.
DISCUSSION
SOUTHEAST ARIZONA CONTINUES TO BE DOMINATED BY STRONG
RIDGING CENTERED TO OUT SOUTHEAST ACROSS NORTHERN MEXICO WITH
ELEVATED HEIGHTS AND THICKNESSES RESULTING IN TEMPERATURES DURING
THIS WARM STRETCH TO PEAK TODAY. HIGHS TODAY WILL BE 15 TO 20
DEGREES ABOVE NORMAL ACROSS THE FORECAST AREA WITH MORE RECORD HIGHS
EXPECTED.
THE AFOREMENTIONED RIDGE WILL CONTINUE TO DRIFT SOUTH AND EAST ON
TUESDAY WITH DEEPER SOUTH TO SOUTHWESTERLY FLOW ESTABLISHING ITSELF
ACROSS AZ AHEAD OF A LONGWAVE TROUGH OFF THE PACIFIC COAST. TUESDAY
WILL CONTINUE TO BE QUITE WARM WITH INCREASING/THICKENING MID AND
HIGH LEVEL CLOUDS.
THE MODELS ARE SHOWING THE FIRST IN A SERIES OF DISTURBANCES MOVING
THROUGH TUESDAY NIGHT INTO WEDNESDAY IN THE SOUTH TO SOUTHWEST FLOW,
WITH THE MAIN FOCUS ON LOCALES FROM TUCSON NORTH AND WESTWARD. WHILE
ANOMALOUSLY HIGH PWATS ARE EXPECTED, AMPLIFIED BY THE ABNORMALLY WARM
TEMPERATURES FOR THIS TIME OF YEAR, THE FORCING/DYNAMICS WILL BE
FAIRLY MEAGER. THEREFORE WITH THE 20%-50% PRECIPITATION CHANCES, QPF
WILL GENERALLY BE LESS THAN 0.10" AND NOT IMPACTFUL. SNOW LEVELS
DURING THIS TIME REMAIN WELL ABOVE MOUNTAIN TOPS GIVEN THE VERY WARM
AIRMASS.
FOR THE DAY WEDNESDAY, SLIGHT CHANCE TO LOW END PRECIPITATION
CHANCES CONTINUE (10%-40%) BUT ANY SHOWER ACTIVITY LOOKS TO BE QUITE
LIGHT WITH ONLY UP TO A FEW HUNDREDTHS OF AN INCH OF PRECIPITATION AS
THE REGION SHOULD GENERALLY BE BETWEEN MORE NOTABLE DISTURBANCES
ALOFT. SOME BREEZES WILL OCCUR WEDNESDAY AFTERNOON WITH SLIGHTLY
COOLER TEMPERATURES AS HIGHS DROP TO ABOUT 10 DEGREES ABOVE NORMAL.
WE SHOULD ALSO NOTE THAT MORNING LOW TEMPERATURES WILL BE ABOUT 15
TO 20 DEGREES ABOVE NORMAL WEDNESDAY AND CHRISTMAS MORNING.
BOTH THE DETERMINISTIC AND ENSEMBLE MODELS ARE TRYING TO FOCUS THE
PERIOD FROM CHRISTMAS EVE INTO CHRISTMAS DAY AS A MORE ACTIVE PERIOD
AS ANOTHER DISTURBANCE PROPAGATES NORTHWARD ON THE SOUTHEAST FLANK
OF THE BROADER TROUGHING TO OUR WEST. OUR AREA WILL ONCE AGAIN BE ON
THE SOUTHERN AND EASTERN EDGE OF THIS SYSTEM BUT WITH CONTINUED
ANOMALOUSLY HIGH PWAT AND ELEVATED IVT VALUES COINCIDING WITH THE
INCREASED LIFT, THERE WILL BE BETTER PRECIPITATION POTENTIAL DURING
THIS PERIOD (30%-70%, HIGHER VALUES NORTH AND WEST OF TUCSON AND
LOWER SOUTH AND EAST). QPF VALUES STILL REMAIN ON THE LIGHT SIDE
RANGING FROM LESS THAN 0.05" ACROSS COCHISE COUNTY UPWARDS TO AROUND
0.25" ACROSS PORTIONS OF PINAL COUNTY AND THE WESTERN DESERTS. WE'LL
CONTINUE TO FINE TUNE THIS OVER THE NEXT COUPLE OF DAYS. SNOW LEVELS
WILL CONTINUE TO REMAIN AT OR ABOVE MOUNTAIN TOP LEVELS THROUGH
CHRISTMAS DAY. TEMPERATURES ON CHRISTMAS WILL REMAIN ABOUT 10
DEGREES ABOVE NORMAL WITH ONCE AGAIN A FEW BREEZES.
FROM FRIDAY INTO THE UPCOMING WEEKEND, CONFIDENCE STARTS TO LOWER ON
THE EASTWARD PROGRESSION OF THE TROUGH WITH VERY SIGNIFICANT
DIFFERENCES BY AROUND SUNDAY WITH THE GFS/GEFS MAINTAINING A
STRONGER UPPER LOW TO OUR WEST COMPARED TO THE ECMWF/EPS/CMCE WHICH
WEAKEN THE SYSTEM WITH RIDGING EVENTUALLY TAKING OVER. GIVEN THIS
UNCERTAINTY, THE NBM POPS (~5%-20%) FRIDAY THROUGH SUNDAY ARE
REASONABLE. TEMPERATURES THIS WEEKEND WILL COOL TO ABOUT 3 TO 6
DEGREES ABOVE NORMAL.
AVIATION
VALID THROUGH 23/12Z.
GENERALLY CLEAR SKIES/SKC CONDIITONS THRU 22/18Z, THEN INCREASING
HIGH CIRRUS CLOUDS WITH SCT-BKN CLOUDS AOA 20K FT AGL BY 23/00Z AND
CONTINUING THROUGH THE END OF THE VALID PERIOD. SFC WIND 10 KNOTS OR
LESS, FAVORING A WLY/NWLY DIRECTION IN THE AFTERNOON/EARLY EVENING
AND VARIABLE IN DIRECTION AT OTHER TIMES. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
WARM AND DRY CONDITIONS CONTINUE THROUGH TUESDAY,
WITH HIGHS 15-20 DEGREES ABOVE NORMAL. A COOLING TREND STARTS ON
WEDNESDAY INTO NEXT WEEKEND, BUT HIGHS WILL STILL BE 5-10 DEGREES
ABOVE NORMAL. TROPICAL MOISTURE WILL STREAM NORTHWARD AHEAD OF A
PACIFIC STORM SYSTEM, RESULTING IN A CHANCE OF LIGHT PRECIPITATION
TUESDAY NIGHT INTO THURSDAY. SLIGHT CHANCES OF PRECIPITATION LINGER
INTO THE WEEKEND BUT CONFIDENCE IS LOW. 20-FOOT WINDS WILL BE 15 MPH
OR LESS AND TERRAIN DRIVEN INTO NEXT WEEKEND. MIN RELATIVE HUMIDITY
VALUES AT ALL ELEVATIONS WILL BE IN THE 10-20 PERCENT RANGE THROUGH
TUESDAY, INCREASING TO 30-45 PERCENT (AND HIGHER IN THE MOUNTAINS)
WEDNESDAY INTO THE WEEKEND.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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