920  
FXUS65 KTWC 062110  
AFDTWC  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TUCSON AZ  
210 PM MST MON OCT 6 2025  
   
SYNOPSIS  
EXPECT A WARMING TREND THIS WEEK AS HIGH TEMPERATURES  
RISE ABOVE NORMAL THROUGH THE WORK WEEK. MOISTURE RETURNS LATE  
THIS WEEK, INITIALLY PROVIDING INCREASED CLOUD COVER AND VERY  
SLIGHT CHANCES FOR SHOWERS WEDNESDAY WITH CHANCES INCREASING LATE  
THIS WEEKEND INTO THE WEEKEND. BEST CHANCES FOR WIDESPREAD RAIN  
LOOK TO BE THIS WEEKEND.  
 
 
   
DISCUSSION  
SKIES ARE CLEAR ACROSS THE CWA UNDER SOUTHWEST FLOW  
ALOFT THANKS TO TROUGHING OVER THE WESTERN U.S. AND A LARGE HIGH  
OVER THE SOUTHEAST. OVER THE NEXT COUPLE OF DAYS THE RIDGE WILL  
EXPAND WESTWARD BECOMING CENTERED OVER TEXAS AND NORTHERN MEXICO  
BY THE MIDDLE OF THE WEEK AND A CLOSED LOW WILL BE MOVING INTO THE  
PACIFIC NORTHWEST. IN THE TROPICS HURRICANE PRISCILLA IS CENTERED  
ABOUT 370 MILES SOUTH OF CABO AND IS FORECASTED TO TRAVEL NORTH  
NORTHWEST DURING THE WEEK PARALLELING THE WEST COAST OF BAJA.  
 
THE POSITIONING OF THE HIGH AND PACIFIC LOW WILL ALLOW  
SOUTHWESTERLY/SOUTHERLY FLOW TO ADVECT TROPICAL MOISTURE FROM  
PRISCILLA INTO THE REGION BEGINNING WEDNESDAY. THURSDAY INTO THE  
WEEKEND PWAT VALUES ARE EXPECTED TO BE 200-250 PERCENT OF NORMAL  
WHICH TRANSLATE TO VALUES AROUND 1.3" AT THE AZ/NM BORDER  
INCREASING TO 1.5" IN TUCSON AND 1.8" IN FAR WESTERN PIMA COUNTY.  
NBM POPS HAVE INCREASED COMPARED TO PREVIOUS FORECASTS, ESPECIALLY  
THURSDAY AND FRIDAY. SLIGHT RAIN CHANCES (15-25 PERCENT) BEGIN  
WEDNESDAY ALONG THE AZ/NM BORDER THEN INCREASE IN COVERAGE THURSDAY  
AND FRIDAY WITH AREA WIDE CHANCES BY THIS WEEKEND GENERALLY 25-45  
PERCENT. LOOKING INCREASINGLY LIKELY FOR MODERATE SHOWERS EACH  
DAY LATE THIS WEEK INTO THE WEEKEND, BUT THE QUESTION STILL  
REMAINS ON COVERAGE OF THUNDERSTORMS AND INTENSITY OF THE RAIN.  
ENSEMBLES PLACE THE PACIFIC LOW OFF THE COAST OF OREGON AND  
WASHINGTON THURSDAY AND FRIDAY WITH HIGH PRESSURE CENTERED OVER  
WEST TEXAS. SYNOPTIC SCALE FORCING WILL BE VERY LIMITED DURING  
THIS TIME WITH HOW FAR AWAY THE LOW IS AND THE PROXIMITY OF THE  
RIDGE. THICK MID-LEVEL CLOUD COVER COULD ALSO HINDER STORM  
INTENSITY WITHOUT THE EXTRA UPPER LEVEL SUPPORT. SO WHILE THERE  
WILL LIKELY BE SHOWER ACTIVITY THANKS TO THE ANOMALOUS MOISTURE,  
AT THIS TIME DON'T EXPECT MORE THAN ISOLATED THUNDERSTORMS AND  
LIMITED HEAVY RAINFALL POTENTIAL. HOWEVER THERE IS STILL SOME  
UNCERTAINTY WITH THE EAST/WEST POSITIONING OF THE TROUGH WHICH  
WILL INFLUENCE RAIN AMOUNTS.  
 
THIS WEEKEND THE LOW OPENS UP AND MOVES INLAND THROUGH THE GREAT  
BASIN AND THE HIGH SHIFTS A LITTLE FURTHER SOUTH INTO MEXICO. THE  
LATEST ENSEMBLE RUNS BRING THE TROUGH FURTHER SOUTH THAN PREVIOUS  
RUNS WHICH HAS RESULTED IN POPS INCREASING THIS WEEKEND. THE BEST  
SYNOPTIC SCALE LIFT WILL STILL BE TO THE NORTH OF THE AREA, BUT  
WITH THE HIGH POSSIBLY MOVING FURTHER SOUTH STORMS WILL HAVE A  
BETTER CHANCE OF PRODUCING HEAVY RAINFALL. STILL A LOT OF  
UNCERTAINTY IN RAIN AMOUNTS WITH FRIDAY-SUNDAY RAIN TOTAL SPREAD  
BETWEEN THE 25TH AND 75TH PERCENTILE GENERALLY 0.5"-1.5" AND  
1.5"-3.0" BETWEEN 10TH AND 90TH. STILL A LOT OF DETAILS TO WORK  
OUT BUT HIGHER CONFIDENCE IN A WET END OF THE WEEK AND WEEKEND,  
AND LOWER CONFIDENCE ON THE HEAVY RAINFALL THREAT. THE HEAVY  
RAINFALL WILL DEPEND ON HOW FAR SOUTH THE LOW ENDS UP. RAIN  
CHANCES CONTINUE INTO EARLY NEXT WEEK AS THE MOISTURE STICKS  
AROUND AND ANOTHER TROUGH MOVES THROUGH THE REGION.  
 
 
   
AVIATION  
VALID THROUGH 08/00Z.  
SCT-BKN CLOUDS AOA 20K FEET IN THE VICINITY OF KOLS AND KDUG  
BEGINNING THIS EVENING THROUGH THE END OF THE PERIOD AND SKC  
ELSEWHERE. SURFACE WINDS BECOMING SOUTHERLY 5-10 KNOTS THROUGH  
THE EARLY EVENING THEN LIGHT AND TERRAIN DRIVEN OVERNIGHT. TUESDAY  
AFTERNOON WINDS BECOME SOUTHERLY 5-10 KTS AGAIN. AVIATION  
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.  
 
 
   
FIRE WEATHER  
MINIMUM RELATIVE HUMIDITIES MAINLY 12-20 PERCENT  
THROUGH TUESDAY. WINDS ON THE LIGHTER SIDE TO START THE WORK  
WEEK, WITH GUSTY SOUTHEASTERLY WINDS IN THE GILA RIVER VALLEY  
WEDNESDAY THROUGH FRIDAY. A PUSH OF MOISTURE SHOULD BEGIN TO BRING  
UP MINIMUM RELATIVE HUMIDITIES THROUGH THE SECOND HALF OF THE  
WEEK. THIS WILL ALSO INCREASE RAIN CHANCES BEGINNING WEDNESDAY  
ALONG THE AZ/NM BORDER THEN OVER MOST OF SOUTHEAST ARIZONA  
THURSDAY INTO THE WEEKEND WITH THE BEST CHANCES THIS WEEKEND.  
 
 
   
TWC WATCHES/WARNINGS/ADVISORIES  
 
NONE.  
 
 
 
 
HARDIN  
 
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