859
FXUS65 KTWC 141711
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
1011 AM MST FRI AUG 14 2026
SYNOPSIS
EXPECT A DOWNTURN IN THUNDERSTORM ACTIVITY STARTING
TODAY AS DRIER AIR BEGINS TO PUSH INTO SOUTHEAST ARIZONA. HOT
CONDITIONS THEN RETURN LATE THIS WEEKEND WITH AN EXTREME HEAT
WATCH IN EFFECT FOR PORTIONS OF SOUTHEAST ARIZONA MONDAY THOUGH
WEDNESDAY OF NEXT WEEK. A MORE ACTIVE THUNDERSTORM PATTERN
RETURNS THE SECOND HALF OF NEXT WEEK.
UPDATE
A GRADUAL DOWNTURN IN THE COVERAGE AND RELATIVE INTENSITY OF SHOWER
AND THUNDERSTORM ACTIVITY IS ANTICIPATED OVER THE NEXT FEW DAYS
STARTING TODAY. HOWEVER, ANY STORMS THAT DO FORM WILL CONTINUE TO
PRESENT A CONCERN FOR HEAVY RAINFALL RATES (0.75 TO 1 INCH PER
HOUR), FREQUENT LIGHTNING, AND POSSIBLY EVEN GUSTY OUTFLOWS TO
AROUND 35 MPH. HIGH RESOLUTION GUIDANCE HAS POINTED TOWARD SHOWER
AND STORM DEVELOPMENT AS EARLY AS 10-11 AM THIS MORNING OVER HIGH
TERRAIN EAST OF TUCSON WHICH IS CONSISTENT TO WHAT IS ALREADY
ONGOING. THE LOWER PORTIONS OF THE ATMOSPHERE REMAIN SATURATED
DESPITE DRIER AIR PUNCHING IN ALOFT WITH PRECIPITABLE WATER BETWEEN
AROUND 1 TO 1.4 INCHES SUPPORTIVE OF HEAVIER DOWNPOURS. MODEST
INSTABILITY IS AVAILABLE TO TAP INTO ALREADY WITH ABOUT 500-1000
J/KG OF MLCAPE WITH CIN ERODING AWAY FROM EAST TO WEST ACROSS THE
AREA.
TOMORROW AND SATURDAY STORM CHANCES DECREASE WITH A SLIGHT CHANCE
(10-20%) MAINLY FOCUSED FROM THE TUCSON METRO EAST AND SOUTH AND
OVER THE HIGHER TERRAIN. DRIER AIR ALOFT COULD ACT TO SUPPRESS
COVERAGE AND INTENSITY OF STORMS ACROSS THE AREA, BUT SURFACE
MOISTURE WILL REMAIN IN PLAY. ALTHOUGH I ANTICIPATE THERE TO BE
NOTABLY LESS COVERAGE THAN TODAY, THE RESIDUAL LOW LEVEL MOISTURE
DOES ADD A LITTLE BIT OF UNCERTAINTY.
DISCUSSION
THE UPPER PATTERN THIS MORNING IS DEFINED BY A
TROUGH OF LOW PRESSURE EXTENDING ALONG THE WEST COAST AND THE
SUBTROPICAL HIGH POSITIONED OVER THE SOUTHEASTERN STATES. THE
DEEP MOIST AIRMASS THAT HAS BEEN BLANKETING SOUTHEAST ARIZONA
WILL BEGIN TO ERODE TODAY AS DRIER AIR (PWATS 1.00-1.25 INCHES
SEEN ON THE GOES PRECIPITABLE WATER IMAGERY) ACROSS NORTHERN
SONORA TRACKS INTO OUR NECK OF THE WOODS BEHIND THE SOUTHWESTERLY
FLOW. THIS SHOULD RESULT IN A SIGNIFICANT DOWNTURN IN THUNDERSTORM
ACTIVITY WITH A LOW-GRADE MONSOON DAY ON TAP. THE BIG QUESTION,
IS HOW MUCH WE CAN DRY OUT TODAY EVEN WITH THE H7 THETA-E RIDGE
NUDGING EAST INTO NM. GIVEN HOW SATURATED THE SOILS ARE ACROSS
THE ENTIRE FORECAST AREA, THIS SHOULD SLOW THE ANTICIPATED
DRYING WITH EASTERN AREAS HOLDING ON THEIR MOISTURE INTO THE
AFTERNOON. THERE SHOULD BE ENOUGH MOISTURE AROUND TODAY FOR
ISOLATED THUNDERSTORMS MAINLY OVER THE HIGHER TERRAIN BUT MAY
STRUGGLE TO SUPPORT THEMSELVES AS THEY MOVE ACROSS THE VALLEYS.
THE DRIER AIR IN THE LOWER-TO-MID LEVELS WILL INCREASE THE
POTENTIAL THAT DOWNDRAFTS WILL RESULT IN GUSTY AND ERRATIC
OUTFLOWS TODAY BUT THIS IMPACT SHOULD REMAIN LOCALIZED. THERE IS
STILL ENOUGH MOISTURE TO SUPPORT BRIEF HEAVY RAINFALL...WHICH
MAY END-UP BEING PROBLEMATIC IN THOSE AREAS WITH EXISTING
SATURATED SOILS FROM THE PAST FEW DAYS.
OTHERWISE, THE BIG STORY WILL BE THE INCREASING HEAT EARLY NEXT
WEEK. THE UPPER-HIGH CENTER ACROSS THE SERN STATES IS EXPECTED
TO MOVE WEST THE NEXT FEW DAYS. IN FACT, THE HIGH SHOULD BE
OVER ERN TX BY 16/00Z SATURDAY AFTERNOON, WRN TX BY 17/00Z
SUNDAY AFTERNOON, THEN OVERHEAD 18/06Z MONDAY EVENING...FINALLY
MAKING ITS WAY TO SOUTHERN CALIFORNIA BY TUESDAY. THE MODEL
850-700MB THICKNESSES INCREASE TO AROUND 1690M NEXT MONDAY AND
TUESDAY WHICH CORRELATES TO AFTERNOON HIGH TEMPERATURES NEAR
106 DEGREES IN TUCSON. THIS WILL ELEVATE THE OVERALL HEATRISK
TO MAJOR FOR THE LOWER DESERTS AND EXTREME FOR SOME LOCALES
INCLUDING TUCSON AND SAFFORD. AN EXTREME HEAT WATCH IS IN
EFFECT MONDAY THROUGH WEDNESDAY FOR A MAJORITY OF PIMA COUNTY,
PINAL COUNTY, SOUTHERN GRAHAM AND GREENLEE COUNTIES. THE UPPER
RIDGE THEN SHIFTS INTO THE GREAT BASIN LATE NEXT WEEK AND NEXT
WEEKEND, WHICH SHOULD OPEN US BACK-UP FOR A MORE ACTIVE THUNDERSTORM
PATTERN.
AVIATION /18Z FRIDAY THROUGH 18Z SATURDAY/
VALID THROUGH 15/12Z. SCT-BKN CLOUDS 12-15K FT AGL
THROUGH 14/19Z THEN SCT-BKN 8-12K FT AGL BKN-OVC 12-15K FT AGL
WITH A SLIGHT CHANCE OF THUNDERSTORMS THIS AFTERNOON INTO THE
EARLY EVENING. GUSTY ERRATIC WINDS OF 30-40 KTS WILL BE POSSIBLE
WITH ANY THUNDERSTORM NOW THROUGH 15/02Z. SFC WINDS TERRAIN
DRIVEN AND LESS THAN 10 KTS THROUGH MIDDAY TODAY, THEN SWLY/WLY
AT 8-12 KTS WITH OCNL GUSTS TO 20 KTS. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
A TROUGH OF LOW PRESSURE ALONG THE WEST COAST
WILL IMPORT DRIER AIR INTO SOUTHEAST ARIZONA STARTING TODAY,
RESULTING IN A LOW-GRADE MONSOON PATTERN WITH A SLIGHT CHANCE
OF STORMS THIS WEEKEND MAINLY SOUTH AND EAST OF TUCSON. A MORE
ACTIVE MONSOON PATTERN SETS IN NEXT WEEK. MINIMUM RELATIVE
HUMIDITY WILL BE 20-40 PERCENT TODAY LOWERING TO AROUND 15-30
PERCENT THEREAFTER. TEMPERATURES WILL BE BELOW NORMAL TODAY,
THEN WARM UP AGAIN TO ABOVE NORMAL LATE THIS WEEKEND AND
ESPECIALLY EARLY NEXT WEEK AS A RIDGE OF HIGH PRESSURE BUILDS
ACROSS THE AREA. OUTSIDE OF THUNDERSTORMS, WINDS WILL BE TERRAIN
DRIVEN AROUND 10 MPH WITH OCCASIONAL AFTERNOON GUSTS TO 20 MPH.
TWC WATCHES/WARNINGS/ADVISORIES
EXTREME HEAT WATCH FROM MONDAY MORNING THROUGH WEDNESDAY
EVENING FOR AZZ501-502-504>506-509.
UPDATE...DVS
VISIT US ON FACEBOOK, X, YOUTUBE, AND AT WEATHER.GOV/TUCSON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page