222
FXUS65 KTWC 070959
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
259 AM MST WED JAN 7 2026
SYNOPSIS
A WINTER WEATHER SYSTEM WILL MOVE ACROSS ACROSS
SOUTHEAST ARIZONA TODAY...RESULTING IN NUMEROUS VALLEY RAIN AND
MOUNTAIN SNOW SHOWERS. THIS SYSTEM WILL BE FOLLOWED BY ANOTHER
COOLER WEATHER SYSTEM THURSDAY RESULTING IN SCATTERED VALLEY RAIN
AND MOUNTAIN SNOW. THIS SECOND SYSTEM WILL ALSO USHER IN UNSEASONABLY
COOL TEMPERATURES TO THE AREA, WITH FREEZING MORNING LOW TEMPERATURES
POSSIBLE ACROSS THE TUCSON METRO AREA FRIDAY AND SATURDAY MORNINGS.
KEY MESSAGES
A SERIES OF WINTER WEATHER SYSTEMS WILL IMPACT SOUTHEAST ARIZONA LATE
THIS MORNING THROUGH THURSDAY NIGHT.
1. WINTER WEATHER ADVISORIES:
A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE MOUNTAINOUS AREAS
INCLUDING THE WHITE MOUNTAINS, GALIURO, PINALENO, CATALINA, AND
RINCON MOUNTAINS FROM 11 AM MST THIS MORNING THROUGH 11 PM MST
THURSDAY EVENING.
2. MOUNTAIN SNOW ACCUMULATIONS:
THE BULK OF THE PRECIPITATION IS EXPECTED TO OCCUR THIS AFTERNOON
INTO THIS EVENING WITH THE SNOW LEVELS AROUND 7000 TO 7500 FEET.
GIVEN THE HIGH MOISTURE CONTENT OF THIS FIRST SYSTEM, SNOWFALL
ACCUMULATIONS WILL BE LIMITED TO 2 TO 6 INCHES DESPITE THE HEAVIER
PRECIPITATION.
THE SECOND PART OF THE STORM SYSTEM WILL RESULT IN ADDITIONAL
WIDESPREAD SNOW DEVELOPING THURSDAY THROUGH THURSDAY EVENING. SNOW
LEVELS WILL DROP TO AROUND 5000 FEET BY THURSDAY EVENING. THIS
SYSTEM IS COLDER AND WILL BE MORE EFFICIENT IN PRODUCING SNOWFALL.
EXPECT AN ADDITIONAL 4 TO 8 INCHES OF SNOWFALL ABOVE 6000 FEET.
TOTAL STORM TOTAL SNOW ACCUMULATIONS TODAY THROUGH THURSDAY WILL
BE 8 TO 12 INCHES ABOVE 8000 FEET WITH LOCALLY HIGHER AMOUNTS AT
THE MOUNTAIN PEAKS. ELEVATIONS BETWEEN 6000 AND 8000 FEET WILL SEE
2 TO 8 INCHES OF SNOW.
2. VALLEY RAINFALL:
WIDESPREAD RAIN SHOWERS FOR THE VALLEYS OF SOUTHEAST ARIZONA TODAY
THROUGH THURSDAY NIGHT. THE HEAVIEST (MODERATE-INTENSITY) RAINFALL
WILL OCCUR THIS AFTERNOON INTO THIS EVENING. RAINFALL RUNOFF MAY
RESULT IN SIGNIFICANT PONDING OF WATER IN NORMALLY DRY WASHES,
ROADWAY DIPS AND OTHER LOW-LYING AREAS. STORM-TOTAL RAINFALL AMOUNTS
BETWEEN 0.25-0.75 INCHES WITH LOCALLY HIGHER AMOUNTS ARE
ANTICIPATED.
3. VERY COLD TO FREEZING TEMPERATURES ARE EXPECTED BOTH FRIDAY AND
SATURDAY MORNING FOR THE VALLEYS FROM TUCSON EAST.
DISCUSSION
THE UPPER PATTERN THIS MORNING IS DEFINED BY A
STRONG UPPER-LOW SPINNING OFF THE COAST OF SRN CALIFORNIA/NRN
BAJA MEXICO AND ANOTHER UPPER-LOW OFF THE COAST OF BRITISH
COLUMBIA CANADA MAKING ITS WAY SE TOWARD THE PACIFIC NORTHWEST.
THE LATEST SATELLITE IMAGERY INDICATED AN ENHANCED PLUME OF
MOISTURE EXTENDING FROM SW OF THE BAJA SPUR, TOWARD THE NE INTO
NW SONORA MEXICO/EXTREME SOUTHERN ARIZONA.
AS THE UPPER-LOW OFF THE COAST OF CANADA MOVES SE TODAY INTO THE
MEAN TROUGH SETUP ACROSS THE WEST COAST, IT WILL FORCE THE STRONG
UPPER-LOW TO OUR WEST TO EJECT EAST...ACROSS NORTHERN SONORA
MEXICO AND SOUTHERN ARIZONA TODAY. THE NOSE OF THAT DEEP MOISTURE
PLUME IS CURRENTLY SOUTH OF THE INTERNATIONAL BORDER OF SOUTHWEST
ARIZONA THIS MORNING, AND WILL CONTINUE TO SHIFT EAST ALONG WITH
THE UPPER-LOW, EVENTUALLY EXPANDING INTO THE CENTRAL PORTIONS OF
OUR CWA BY MID-DAY TODAY...THEN ACROSS THE SOUTHEAST HALF OF THE
CWA BY THIS AFTERNOON. ENSEMBLE MEANS STILL BULLISH WITH THE
MAGNITUDE OF THIS MOISTURE, DEPICTING PRECIPITABLE WATER VALUES
BETWEEN 200-300 PERCENT OF NORMAL FOR THIS TIME OF YEAR. STRONG
LOWER-LEVEL MOISTURE CONVERGENCE WILL 'PRIME THE PUMP' FOR THE
PASSAGE OF THE UPPER TROUGH AXIS TRACKING ACROSS OUR NECK OF THE
WOODS THIS AFTERNOON INTO THIS EVENING. MODERATE MID-LEVEL LIFT/
DEFORMATION AHEAD OF THE TROUGH IN THE DENDRITIC GROWTH ZONE
SHOULD INCREASE THE OVERALL PRECIPITATION EFFICIENCY OF THE SYSTEM.
EXPECT THIS SYSTEM TO INITIALLY PRODUCE LIGHT-INTENSITY PRECIPITATION
AS THE PLUME SPREADS OUT ACROSS THE AREA THIS MORNING INTO THE
EARLY AFTERNOON, THEN INCREASE IN COVERAGE AND INTENSITY TO MORE
MODERATE-INTENSITY PRECIPITATION THIS AFTERNOON AND THIS EVENING.
OVERALL QPF AMOUNTS WITH THIS FIRST SYSTEM SHOULD PRODUCE BETWEEN
0.25-0.75 INCHES IN THE VALLEYS, AND 1.00 TO 1.25 INCHES OF WATER
EQUIVALENT ON THE MOUNTAIN TOPS. THIS WILL RESULT IN 2-6 INCHES
OF SNOWFALL ACCUMULATION ABOVE 7500-8000 FEET TODAY AND TONIGHT.
DESPITE THE HEAVIER QPF EXPECTED, THE HIGH MOISTURE CONTENT OF THE
MOISTURE PLUME WILL KEEP SNOWFALL RATIOS VERY LOW FOR THIS FIRST
SYSTEM...THUS MAKING SNOWFALL ACCUMULATIONS STRUGGLE. THE MOST
IMPACTFUL ASPECT OF THIS FIRST SYSTEM WILL BE THE MODERATE-
INTENSITY RAINFALL IN THE VALLEYS THIS AFTERNOON/EVENING. RAINFALL
RUNOFF FROM THESE STORMS MAY RESULT IN SIGNIFICANT PONDING OF
WATER IN NORMALLY DRY WASHES, ROADWAY DIPS AND OTHER LOW-LYING
AREAS.
THE UPPER-LOW RESPONSIBLE FOR KICKING THIS FIRST FEATURE ACROSS
US TODAY WILL CONTINUE TO DIVE INTO THE GREAT BASIN TONIGHT AND
EVENTUALLY INTO NORTHEAST ARIZONA THURSDAY. THIS SYSTEM IS MUCH
COLDER, BUT ARRIVES A LITTLE TOO LATE TO WORK WITH THE AVAILABLE
MOISTURE WITH THE FIRST SYSTEM. IT WILL, HOWEVER, BE COLD ENOUGH
TO WRING OUT THE RESIDUAL MOISTURE TO SUPPORT SCATTERED VALLEY
RAIN AND MOUNTAIN SNOW THURSDAY. THE SYSTEM WILL HAVE BETTER
DYNAMICS ASSOCIATED WITH IT, ESPECIALLY ACROSS THE NORTHERN
PORTIONS OF GRAHAM AND GREENLEE COUNTY THURSDAY EVENING. QPF
AMOUNTS FOR THIS SECOND SYSTEM SHOULD BE AROUND A QUARTER INCH IN
THE VALLEYS TO 0.75-1.00 INCHES IN THE MOUNATINS. DESPITE THE
LOWER QPF AMOUNTS, I WOULD EXPECT THIS SYSTEM TO BE MORE
EFFICIENT THAN THE FIRST SYSTEM IN PRODUCING SNOWFALL. EXPECT THIS
SECOND SYSTEM TO BRING AN ADDITIONAL 4-8 INCHES OF SNOWFALL ABOVE
6000 FEET, ESPECIALLY ACROSS THE PINALENO AND WHITE MOUNTAINS. STORM
TOTAL SNOWFALL ACCUMULATIONS TODAY THROUGH THURSDAY WILL BE 8 TO
12 INCHES ABOVE 8000 FEET WITH LOCALLY HIGHER AMOUNTS AT THE
MOUNTAIN PEAKS. ELEVATIONS BETWEEN 6000 AND 8000 FEET WILL SEE 2
TO 8 INCHES OF SNOW. THE SNOWFALL ACCUMULATIONS IN THE MOUNTAINS
WILL BE THE MORE IMPACTFUL ELEMENT OF THE SECOND WEATHER SYSTEM
THURSDAY. WE HAVE A WINTER WEATHER ADVISORY IN EFFECT FOR THE
MOUNTAINOUS AREAS INCLUDING THE WHITE MOUNTAINS, GALIURO,
PINALENO, CATALINA, AND RINCON MOUNTAINS FROM 11 AM MST THIS
MORNING THROUGH 11 PM MST THURSDAY EVENING.
OTHERWISE, COLD AIR IN THE WAKE OF THIS SECOND SYSTEM WILL USHER
IN UNSEASONABLY COOL MORNING LOW TEMPERATURES TO THE AREA, WITH
FREEZING TEMPERATURES ACROSS THE VALLEYS FROM TUCSON EAST FRIDAY
AND SATURDAY MORNINGS. THE 07/09Z NBM PROBABILITY FOR MINIMUM
TEMPERATURES AT THE TUCSON INTERNATIONAL AIRPORT (KTUS) AT OR
BELOW FREEZING (32 DEGREE F) IS 26% FRIDAY MORNING, INCREASING TO
82% SATURDAY MORNING. OTHERWISE, AFTERNOON TEMPERATURES ARE
FORECAST TO FALL BELOW NORMAL WILL THIS SYSTEM THURSDAY INTO THE
WEEKEND.
AVIATION
VALID THROUGH 08/12Z. SCT-BKN 12-15K FT AGL BKN-OVC
AOA 20K FT AGL THRU 07/17Z, THEN SCT-BKN 6-10K FT AGL BKN-OVC
12-15K FT AGL WITH SCT -SHRA. AFT 07/22Z, SCT-BKN 4-8K FT AGL
BKN-OVC 8-10K FT AGL WITH SCATTERED TO NUMEROUS -SHRA THRU THE
END OF THE PERIOD. CIGS 2-5K FT AGL DURING THE LATE AFTERNOON AND
EARLY EVENING WITH MTN OBSCURATIONS POSSIBLE. A FEW EMBEDDED
-TSRA ARE POSSIBLE. SFC WINDS LIGHT AND TERRAIN DRIVEN THIS
MORNING, THEN SLY/SWLY 10-12 KTS AFT 07/17Z. GUSTS TO 25 KTS WILL
BE POSSIBLE NEAR THE STRONGER SHOWERS THIS AFTERNOON AND THIS
EVENING. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
A SERIES OF WINTER WEATHER SYSTEMS WILL IMPACT
SOUTHEAST ARIZONA LATE THIS MORNING THROUGH THURSDAY NIGHT,
RESULTING IN NUMEROUS VALLEY RAIN AND MOUNTAIN SNOW SHOWERS. THE
HEAVIEST (MODERATE-INTENSITY) PRECIPITATION WILL OCCUR THIS
AFTERNOON INTO THIS EVENING. ANOTHER COOLER WEATHER SYSTEM WILL
THEN MOVE ACROSS THE AREA THURSDAY, RESULTING IN SCATTERED VALLEY
RAIN AND MOUNTAIN SNOW.
THE SECOND SYSTEM WILL BE MORE EFFICIENT AT PRODUCING ACCUMULATING
MOUNTAIN SNOWFALL THAN THE FIRST SYSTEM. A WINTER WEATHER ADVISORY
IS IN EFFECT FOR THE WHITE MOUNTAINS, CATALINA AND PINALENO MOUNTAINS
LATE THIS MORNING THROUGH LATE THURSDAY NIGHT. THIS SECOND SYSTEM
WILL ALSO USHER IN UNSEASONABLY COOL MORNING LOW TEMPERATURES TO
THE AREA, WITH FREEZING TEMPERATURES ACROSS THE VALLEYS FROM
TUCSON EAST FRIDAY AND SATURDAY MORNINGS. OTHERWISE, AFTERNOON
TEMPERATURES ARE FORECAST TO FALL BELOW NORMAL WILL THIS SYSTEM
THURSDAY INTO THE WEEKEND. MINIMUM RHS TODAY AND THURSDAY BETWEEN
50-60 PCT IN THE VALLEYS AND 75-90 PCT IN THE MOUNATINS, LOWERING
TO 25-35 PCT IN THE VALLEYS AND 35-45 PCT IN THE MOUNATINS TODAY
FRIDAY INTO THE WEEKEND. GUSTY EAST TO SOUTHEAST WINDS WILL
DEVELOP LATE THIS WEEKEND.
TWC WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 11 PM MST
THURSDAY FOR AZZ510-511-514.
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