194  
FXUS65 KTWC 182019  
AFDTWC  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TUCSON AZ  
119 PM MST SAT OCT 18 2025  
   
SYNOPSIS  
ONE MORE AFTERNOON OF BELOW NORMAL TEMPERATURES THEN  
TEMPERATURES WARM TO NORMAL TO A FEW DEGREES ABOVE NORMAL TOMORROW  
INTO THE MIDDLE OF NEXT WEEK. DRY CONDITIONS WILL ALSO PREVAIL  
THROUGH TUESDAY WITH A SLIGHT CHANCE OF RAIN FOR MOUNTAIN AREAS EAST  
OF TUCSON WEDNESDAY.  
 
 
   
DISCUSSION  
THIS AFTERNOON SOUTHEAST ARIZONA WAS SITUATED  
BETWEEN A WEAK CLOSED UPPER LOW OFF THE COAST OF CALIFORNIA AND  
BAJA CALIFORNIA AND A RIDGE OF HIGH PRESSURE BUILDING OVER CENTRAL  
MEXICO. FEW TO SCATTERED HIGH CLOUDS EXPECTED THIS AFTERNOON WITH  
HIGH TEMPERATURES RUNNING BELOW NORMAL BY AROUND 4 TO 8 DEGREES.  
AS THE RIDGE OF HIGH PRESSURE CONTINUES TO BUILD, EXPECT  
TEMPERATURES TO RISE ABOVE NORMAL INTO THE UPPER 80S TO AROUND 90  
DEGREES TOMORROW RESULTING IN MINOR HEATRISK TO RETURN FOR VALLEY  
LOCATIONS. CURRENT NBM PROBABILITIES FOR 90 DEGREES OR GREATER IN  
TUCSON ARE 10 PERCENT SUNDAY AND MONDAY, 60 PERCENT ON TUESDAY,  
50 PERCENT WEDNESDAY, AND DECREASING TO 5 PERCENT THURSDAY.  
OTHERWISE, LITTLE TO NO WEATHER RELATED IMPACTS EXPECTED THIS  
WEEKEND.  
 
THE NEXT POTENTIAL FOR MINOR/NUISANCE IMPACTS WILL BE WEDNESDAY  
AS THE AFOREMENTIONED UPPER LOW OPENS INTO A TROF AND PASSES OVER  
CENTRAL ARIZONA. A MODEST INCREASE IN MID-LEVEL MOISTURE AND  
FORCING FOR ASCENT AIDED BY TERRAIN WILL BRING SCATTERED TO BROKEN  
CLOUDS TUESDAY THROUGH THURSDAY AND SLIGHT CHANCES (10-25%) FOR  
SHOWERS MAINLY IN THE WHITE MOUNTAINS, CHIRICAHUA MOUNTAINS, AND  
SKY ISLANDS WEDNESDAY. NOT MUCH IN THE WAY OF MEASURABLE RAINFALL  
IS CURRENTLY ANTICIPATED WITH NBM QPF REMAINING UNDER 0.05".  
LOCALLY BREEZY/GUSTY WINDS ARE POSSIBLE WITH THE PASSAGE OF THIS  
SYSTEM PRIMARILY FOR WIND PRONE VALLEY LOCATIONS WEDNESDAY  
AFTERNOON. ONLY LOCALIZED MINOR/NUISANCE IMPACTS ARE CURRENTLY  
EXPECTED AS NBM PROBABILITIES FOR GUSTS OVER 25 MPH ARE LOW  
(10-30%). THE TROF WILL EXIT THE AREA THURSDAY LEAVING SLIGHTLY  
COOLER TEMPERATURES IN ITS WAKE.  
 
LOOKING AHEAD AT THE EXTENDED FORECAST, THE CLIMATE PREDICTION  
CENTER (CPC) DEPICTS TEMPERATURES TO LEAN ABOVE NORMAL AND  
PRECIPITATION TO BE BELOW NORMAL FOR SOUTHEAST ARIZONA. ENSEMBLES  
CURRENTLY AGREE THAT POSITIVE HEIGHT ANOMALIES WILL BE IN PLACE  
THROUGH THE LAST WEEK OF OCTOBER WITH A RIDGE OF HIGH PRESSURE  
BUILDING AND REMAINING IN PLACE OVER THE DESERT SOUTHWEST. THIS  
SOLUTION WOULD SUPPORT CONTINUED WARM AND DRY CONDITIONS TO CLOSE  
OUT OCTOBER.  
 
 
   
AVIATION  
VALID THROUGH 20/12/00Z.  
FEW-SCT CLOUDS AOA 20K FT AGL. SFC WINDS WLY/NWLY AT 6-9 KTS THROUGH  
19/03Z AND AGAIN AFTER 19/20Z. OTHERWISE, SFC WINDS LIGHT AND VRBL.  
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.  
 
 
   
FIRE WEATHER  
MINIMUM RH VALUES WILL BE IN THE 15-25 PERCENT  
RANGE IN THE VALLEYS INTO NEXT WEEK. 20-FOOT WINDS MAINLY 15 MPH OR  
LESS, WITH OCCASIONAL GUSTS TO 20-25 MPH. CHANCE FOR BREEZY WINDS  
WEDNESDAY AS A WEATHER SYSTEM MOVES THROUGH. HIGH TEMPERATURES WILL  
BE BELOW NORMAL THIS AFTERNOON, WARMING TO NORMAL OR JUST ABOVE  
NORMAL LEVELS TOMORROW INTO NEXT WEEK. EXPECT DRY CONDITIONS OVER  
THE NEXT 7 DAYS WITH THE EXCEPTION OF THE WHITE MOUNTAINS WEDNESDAY,  
WHICH WILL SEE A 20 PERCENT CHANCE FOR SHOWERS.  
 
 
   
TWC WATCHES/WARNINGS/ADVISORIES  
NONE.  
 
 
 
 
 
DVS  
 
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