184
FXUS65 KTWC 241709
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
1009 AM MST FRI JUL 24 2026
SYNOPSIS
EXPECT ISOLATED THUNDERSTORM ACTIVITY SOUTH AND WEST
OF TUCSON TODAY AS THE COMBINATION OF DRIER AIR AND A RIDGE OF
HIGH PRESSURE ALOFT MOVE INTO THE REGION. HIGH TEMPERATURES
WILL BE 8 TO 12 DEGREES ABOVE NORMAL AND AS A RESULT AN EXTREME
HEAT WARNING IS IN EFFECT TODAY AND SATURDAY. THE UPPER LEVEL
PATTERN WILL THEN BECOME MORE FAVORABLE FOR MORE WIDESPREAD
THUNDERSTORM ACTIVITY SATURDAY INTO NEXT WEEK.
UPDATE
17Z SATELLITE IMAGERY SHOWED BUBBLING CUMULUS OVER THE SKY
ISLANDS WITH A MORNING OF STRONG SURFACE HEATING AND 60+ DEGREE
DEW POINTS. THE RIDGE CENTER REMAINS CLOSE ENOUGH TO
SOUTHEASTERN ARIZONA TO SUPPRESS MORE WIDESPREAD CHANCES FOR
THUNDERSTORM DEVELOPMENT TODAY, HOWEVER THE HOT SURFACE
TEMPERATURES AND DEW POINTS (WHICH SHOULD LAND IN THE UPPER 50S
TODAY AFTER BOUNDARY LAYER MIXING) WILL ALLOW FOR ISOLATED
THUNDERSTORMS THIS AFTERNOON AND EVENING. STEEP LOW LEVEL LAPSE
RATES SHOWN ON THE INVERTED-V FORECAST SOUNDINGS TODAY AND
AROUND 20 KTS OF EFFECTIVE SHEAR WILL PRODUCE A SEVERE WIND
THREAT WITH ANY THUNDERSTORM THAT DOES DEVELOP. AS PREVIOUSLY
DISCUSSED RECENT HIGH-RESOLUTION GUIDANCE GENERALLY FAVORS
CONVECTION COMING OFF THE WHITE MOUNTAINS INTO GRAHAM AND
GREENLEE COUNTIES AS WELL AS FROM SANTA CRUZ COUNTY WEST/NORTH
THROUGH CENTRAL PIMA, THOUGH MUST OF SOUTHEASTERN ARIZONA HAS A
NON-ZERO CHANCE OF A THUNDERSTORM TODAY. ACTIVITY SHOULD WANE
WITH THE LOSS OF SURFACE HEATING THIS EVENING WITH A VERY
ISOLATED CHANCE OF OVERNIGHT ACTIVITY NEAR THE INTERNATIONAL
BORDER.
DISCUSSION
HIGH PRESSURE IS CURRENTLY CENTERED JUST TO THE
EAST OVER SOUTHERN NEW MEXICO WITH PWAT VALUES RIGHT AROUND
NORMAL FOR THIS TIME OF YEAR. THUNDERSTORM ACTIVITY WILL BE
SUBDUED AGAIN TODAY THANKS TO THE PROXIMITY OF THE RIDGE. HI-RES
GUIDANCE SHOWS ISOLATED ACTIVITY MOSTLY SOUTH AND WEST OF
TUCSON AS WELL AS THE WHITE MOUNTAINS. THE MAIN THREAT WILL BE
OUTFLOW WINDS TO 40 MPH WITH MAYBE A COUPLE GUSTS TO 50 MPH IN
THE STRONGER STORMS AND LOCALLY HEAVY RAINFALL.
WITH THE RIDGE ALMOST DIRECTLY OVERHEAD TEMPERATURES WARM
FURTHER TODAY AND SATURDAY WITH HIGHS RUNNING 8-12 DEGREES ABOVE
NORMAL. THE TUCSON METRO AREA HAS A 30-70 PERCENT CHANCE TO HIT
110 DEGREES BOTH FRIDAY AND SATURDAY WITH AREAS FURTHER WEST
LIKE AJO AND ORGAN PIPE NATIONAL MONUMENT SEEING 15-30 PERCENT
CHANCES TO HIT 115 DEGREES SATURDAY. AREAS SOUTH AND EAST OF
TUCSON WILL SEE HIGHS 100-105 DEGREES. LOW TEMPERATURES WILL
ALSO BE ON THE WARMER SIDE GENERALLY ABOVE 80 DEGREES FROM
TUCSON WESTWARD THANKS IN PART TO DEWPOINTS AROUND 60 DEGREES.
THIS WILL LEAD TO WIDESPREAD AREAS OF MAJOR HEATRISK AND AREAS
OF EXTREME HEATRISK IN THE SAFFORD AREA, TUCSON METRO, AND
WESTERN/CENTRAL PIMA COUNTY. BECAUSE OF THIS AN EXTREME HEAT
WARNING IS IN EFFECT FRIDAY AND SATURDAY.
SATURDAY EXPECT AN UPTICK IN THUNDERSTORM CHANCES AND COVERAGE
AS THE RIDGE MOVES NORTHWARD AND BECOMES CENTERED NEAR THE FOUR
CORNERS. PWAT VALUES WILL RANGE FROM 1.2"-1.5" WITH PLENTY OF
INSTABILITY IN THE AFTERNOON AND EVENING. MODELS ALSO SHOW
MODEST MID LEVEL FLOW OF 15-20 KNOTS AT 500 MB. STORMS LIKELY
FORM FIRST OVER THE HIGHER TERRAIN AND SKY ISLANDS DURING THE
FIRST PART OF THE AFTERNOON THEN MOVE INTO THE LOWER DESERTS
WITH STORM COVERAGE INCREASING LATE AFTERNOON INTO THE EVENING
FROM CENTRAL PIMA COUNTY EASTWARD. STORMS WILL BE CAPABLE OF
STRONG TO SEVERE WIND GUSTS WITH BLOWING DUST A POSSIBLE ISSUE
ALONG I-10 IN PINAL COUNTY. SPC HAS MOST OF SOUTHEAST ARIZONA
UNDER A MARGINAL RISK FOR SEVERE WIND GUSTS SATURDAY. HEAVY
RAINFALL WILL ALSO BE A THREAT WITH LOCALIZED FLASH FLOODING
POSSIBLE.
MID-LEVEL WINDS WEAKEN SOME SUNDAY INTO MONDAY, BUT STILL EXPECT
DAILY THUNDERSTORM ACTIVITY WITH THE HIGH CENTERED OVER THE FOUR
CORNERS. EXPECT NORMAL MONSOON HAZARDS FROM STORMS WITH STRONG
GUSTY OUTFLOW WINDS AND LOCALLY HEAVY RAINFALL. HIGH
TEMPERATURES ALSO BEGIN TO DECREASE SUNDAY FALLING TO AROUND
NORMAL MONDAY INTO WEDNESDAY. ENSEMBLES SHOW A MODEST INCREASE
IN MID-LEVEL FLOW TUESDAY AND WEDNESDAY WHICH COULD LEAD TO AN
INCREASED THREAT OF STRONG TO SEVERE THUNDERSTORMS. REGARDLESS
FROM SATURDAY INTO NEXT WEEK EXPECT DAILY MONSOON THUNDERSTORM
ACTIVITY WITH NORMAL VARYING DEGREES OF COVERAGE AND INTENSITY
EACH DAY.
AVIATION
VALID THROUGH 24/12Z. FEW-SCT CLOUDS AOA 15K FT
AGL THIS MORNING THEN FEW-SCT 8K-12K FT AGL THIS AFTERNOON AND
EVENING. ISOLATED TSRA WILL BE POSSIBLE SOUTH AND WEST OF TUCSON
THIS AFTERNOON AND EVENING WITH THE LIKELIHOOD OF STORMS
IMPACTING A TERMINAL LOW (10-20 PERCENT). SURFACE WINDS LIGHT
AND TERRAIN UNDER 8 KTS THIS MORNING BECOMING NORTHWEST 5-10 KTS
THIS AFTERNOON. ANY THUNDERSTORM IN THE VICNITY MAY PRODUCE A
WIND GUST UP TO 35 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.
FIRE WEATHER
A RIDGE OF HIGH PRESSURE ALOFT WILL RAISE
TEMPERATURES 8 TO 12 DEGREES ABOVE NORMAL TODAY AND SATURDAY.
THIS TREND WILL ALSO REDUCE THUNDERSTORM CHANCES ON FRIDAY TO
JUST ISOLATED COVERAGE IN THE AFTERNOON AND EVENING MAINLY SOUTH
AND WEST OF TUCSON AND IN THE WHITE MOUNTAINS. MINIMUM RELATIVE
HUMIDITY VALUES FRIDAY AND SATURDAY FALL TO 15-20 PERCENT IN
DESERT LOCATIONS WHILE WINDS OVERALL WILL BE LIGHT AND UNDER 12
MPH. DEEPER MOISTURE IS EXPECTED TO RETURN THROUGH THE WEEKEND
WITH INCREASING THUNDERSTORM CHANCES LATE SATURDAY AFTERNOON
THROUGH THE EVENING. ANY THUNDERSTORM MAY COME WITH THE THREAT
OF STRONG GUSTY WINDS AND HEAVY RAIN. DAILY CHANCES FOR
THUNDERSTORMS RETURN IN THE FOLLOWING DAYS INTO NEXT WEEK.
MINIMUM RELATIVE HUMIDITY VALUES SHOULD RISE AS WELL SUNDAY
THROUGH THE FIRST HALF OF NEXT WEEK.
TWC WATCHES/WARNINGS/ADVISORIES
AIR QUALITY ALERT UNTIL 9 PM MST THIS EVENING FOR AZZ504.
EXTREME HEAT WARNING UNTIL 8 PM MST SATURDAY FOR AZZ501>509.
UPDATE...EDWARDS
DISCUSSION...HARDIN
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