598
FXUS65 KTWC 200809
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
109 AM MST WED MAY 20 2026
SYNOPSIS
A DRY WEATHER SYSTEM TO OUR NORTH WILL BRING
SOUTHWESTERLY BREEZES TODAY WITH SLIGHTLY LESS WIND THEREAFTER
INTO THE WEEKEND. TEMPERATURES WILL BE SLIGHTLY BELOW TO NEAR
NORMAL FOR THE REST OF THE WEEK WITH MINOR HEATRISK. ANOTHER
WEATHER SYSTEM WILL BE MOVING INTO THE REGION BY THE START OF
THE NEW WEEK, BRINGING SLIGHT CHANCES FOR RAIN SHOWERS AND
THUNDERSTORMS.
DISCUSSION
WATER VAPOR IMAGERY THIS MORNING CONTINUES TO SHOW
A BROAD TROUGH AXIS ACROSS UTAH TOWARDS BAJA CALIFORNIA. HIGH
LEVEL MOISTURE WILL CONTINUE TO EJECT INTO THE REGION IN A FORM
OF CLOUDY SKIES. THIS TROUGH WILL CONTINUE ANOTHER DAY OF
SOUTHWESTERLY BREEZES ACROSS THE REGION. AS A RESULT, ELEVATED
FIRE WEATHER CONDITIONS WILL EXIST FOR THE AREAS EAST AND SOUTH
OF TUCSON.
A SHOT OF ENERGY FROM THE PACIFIC NORTHWEST WILL PUSH THE UPPER
LEVEL TROUGH OFF TOMORROW, BUT IT WILL LEAVE BEHIND A WEAK LOW
CIRCULATION JUST EAST OF BAJA CALIFORNIA. THIS LOW WILL
TRANSITION TO OUR SOUTH THROUGHOUT THE WEEK. WINDS WILL START
LESSEN MORE ON THURSDAY THROUGH THE START OF THE WEEKEND. THE
WEAK LOW WILL BRING UPPER ATMOSPHERIC MOISTURE INTO THE REGION
BY THE END OF THE WEEK. CHANCES FOR RAIN SHOWERS WILL BE LESS
THAN 10% WITH THIS FORECAST PACKAGE AND MAINLY BE CLOUD BUILD
UPS AND VIRGA FOR FRIDAY AND SATURDAY AFTERNOON.
CHANCES FOR RAIN SHOWERS AND THUNDERSTORMS WILL BE INCREASING ON
SUNDAY THROUGH TUESDAY. A MINOR RIDGE WILL FORM TO OUR EAST WITH
ANOTHER LOW PRESSURE COMING FROM THE PACIFIC WHICH WILL BRING
BETTER MOISTURE INTO THE REGION. ENSEMBLE MODEL PRECIPITABLE
WATER CONTENT WILL INCREASE UP TO 0.61-0.78 INCHES; THE
25TH-75TH PERCENTILE AT TUCSON. LEADING TO 10-30% CHANCES FOR
RAIN SHOWERS AND THUNDERSTORMS ON MONDAY WITH THE HIGHER
CHANCES FOR AREAS EAST OF TUCSON. FORECASTED RAINFALL AMOUNTS
WILL BE ON THE LOW END, LESS THAN 0.1 INCHES FOR THIS EVENT
WHICH INDICATES A MORE OF A DRY THUNDERSTORM ENVIRONMENT FOR THE
SOUTHEAST ARIZONA.
AVIATION
VALID THROUGH 21/12Z.
SCT-BKN CLOUDS AOA 20K FEET AGL AND ANOTHER FEW-SCT LAYER AT OR
AROUND 15K FEET AGL THROUGH THE DAYTIME PERIOD. SKC CONDITIONS
WILL PREVAIL AFTER 21/03Z FROM THE WEST AND CLEARING EAST
THROUGH THE END OF THE FORECAST PERIOD. SFC WINDS THIS MORNING
LESS THAN 12 KTS AND SLY/SELY, AND AGAIN AFTER 21/04Z. BY
20/18Z, SFC WINDS SWLY/WLY AT 10-18 KTS WITH GUSTS UP HIGH AS 30
KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
DRY AND BREEZY CONDITIONS TODAY RESULTING IN ELEVATED FIRE
WEATHER CONDITIONS FOR AREAS EAST AND SOUTH OF TUCSON WITH
BRIEF LOCALLY NEAR CRITICAL CONDITIONS EXISTING IN THE
SOUTHEASTERN PORTION OF COCHISE COUNTY. FOR THURSDAY THROUGH
SUNDAY, WINDS WILL BE GENERALLY BE LESS THAN 15 MPH WITH MIN
RELATIVE HUMIDITIES SITTING IN THE TEENS TO THE MID-20S. MID TO
UPPER LEVEL MOISTURE WILL APPROACH AS EARLY AS THIS WEEKEND
SOUTH AND EAST OF TUCSON, BUT THE MORE IMPACTFUL MOISTURE WILL
LIKELY HOLD OFF UNTIL EARLY NEXT WEEK AS ANOTHER WEATHER SYSTEM
APPROACHES. THERE IS A 10 TO 30 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS MONDAY FOR MUCH OF SOUTHEAST ARIZONA, AND THESE
CHANCES WILL TREND TOWARDS THE NEW MEXICO BORDER TUESDAY,
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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