514
FXUS65 KTWC 180754
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
1253 AM MST SUN JAN 18 2026
SYNOPSIS
HIGH PRESSURE ALONG THE WEST COAST WILL RESULT IN ABOVE
NORMAL HIGH TEMPERATURES AND DRY CONDITIONS THROUGH THE MIDDLE OF
THE WEEK. A LOW PRESSURE SYSTEM MOVING INTO SOUTHEAST ARIZONA FROM
THE EASTERN PACIFIC WILL RESULT IN A SLIGHT CHANCE OF VALLEY RAIN
AND MOUNTAIN SNOW ACROSS SOUTHEAST ARIZONA NEXT WEEKEND.
DISCUSSION
NO CHANGES IN THE NEAR TERM VERSUS 24 HOURS AGO, WITH
HIGH PRESSURE ALOFT IN CONTROL OF THE WEATHER ACROSS THE DESERT
SOUTHWEST THROUGH AT LEAST THE MIDDLE OF THE WEEK AND NO WEATHER
IMPACTS. ABOVE NORMAL HIGH TEMPERATURES WILL CONTINUE, ALONG WITH
PERIODS OF HIGH CLOUDS AND LIGHT WINDS THROUGH THE MIDDLE OF THE
WEEK.
LATE THIS WEEK, BOTH THE DETERMINISTIC GFS/ECMWF CONTINUE TO SHOW A
SOUTHERN STREAM UPPER LOW MOVING INTO THE DESERT SOUTHWEST FROM THE
EASTERN PACIFIC. CLUSTER ANALYSIS CONTINUES TO INDICATE THAT THIS
SOLUTION IS NOT A GIVEN, WITH A FEW MEMBERS HOLDING ONTO RIDGING
ACROSS THE AREA. BOTH THE GFS/ECMWF NOW DEPICT A SLOWER TIMING OF
THE SYSTEM, WITH THE UPPER LOW MOVING ACROSS THE REGION IN THE
SATURDAY/SUNDAY TIME FRAME. THIS SLOWER SOLUTION SEEMS REASONABLE
GIVEN THE CUT-OFF NATURE OF UPPER LOW AND TRAJECTORY OF THE LOW
UNDERCUTTING THE RIDGE. OUR CURRENT FORECAST REFLECTS THE SLIGHT
CHANCE OF VALLEY RAIN/MOUNTAIN SNOW AND COOLER TEMPERATURES FOR
FRIDAY NIGHT THROUGH SUNDAY OF THIS/NEXT WEEK.
AVIATION
VALID THROUGH 19/12Z.
INCREASING HIGH LEVEL CIRRUS CLOUDS THIS MORNING, WITH SCT-BKN
CLOUDS AOA 20K FT AGL BY 18/18Z AND CONTINUING THRU THE REMAINDER OF
THE FORECAST PERIOD. SFC WIND LESS THAN 10 KTS, FAVORING A NLY/NELY
DIRECTION DURING THE AFTERNOON/EARLY EVENING HOURS AND VARIABLE IN
DIRECTION AT OTHER TIMES. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.
FIRE WEATHER
HIGH PRESSURE ALOFT WILL RESULT IN ABOVE NORMAL HIGH
TEMPERATURES AND DRY CONDITIONS THROUGH AT LEAST THE MIDDLE OF THE
WEEK. 20-FOOT WINDS WILL BE LESS THAN 15 MPH AND TERRAIN DRIVEN.
MINIMUM RHS WILL BE IN THE 12-20 PERCENT AT ALL ELEVATIONS THROUGH
MONDAY, WITH AN INCREASE OF 5-10 PERCENT ACROSS THE EASTERN HALF OF
SOUTHEAST ARIZONA TUESDAY THROUGH THURSDAY OF NEXT WEEK. A LOW
PRESSURE SYSTEM MOVING INTO SOUTHEAST ARIZONA FROM THE EASTERN
PACIFIC WILL RESULT IN A SLIGHT CHANCE OF VALLEY RAIN AND MOUNTAIN
SNOW ACROSS SOUTHEAST ARIZONA NEXT WEEKEND, ALONG WITH INCREASING
MINIMUM RHS.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
ZELL
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