794  
FXUS65 KTWC 240404  
AFDTWC  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TUCSON AZ  
904 PM MST MON OCT 23 2017  
   
SYNOPSIS
 
THE HEAT CONTINUES WITH NEAR RECORD HIGH TEMPERATURES  
WEST OF TUCSON ON TUESDAY. TEMPERATURES THEN GRADUALLY DECREASE THE  
REST OF THE WEEK, BUT REMAIN ABOVE AVERAGE FOR LATE OCTOBER. DRY  
CONDITIONS ALSO PREVAIL, WITH A PERIOD OF STRONG EASTERLY WINDS ON  
TUESDAY INTO EARLY WEDNESDAY.  
 

 
   
DISCUSSION
 
STRONG UPPER-LEVEL RIDGING PROVIDED A HOT AND CLEAR  
DAY ACROSS SOUTHEASTERN ARIZONA THIS AFTERNOON. RECORD HIGH  
TEMPERATURES WERE RECORDED IN BOTH TUCSON (96F) AND DOUGLAS (91F).  
TEMPS HAVE SINCE DECREASED QUICKLY IN THIS VERY DRY REGIME, AS  
EVIDENT IN THE 24/00Z SOUNDING THAT SHOWED 0.26" OF PRECIPITABLE  
WATER. NOTHING OF GREAT SIGNIFICANCE IS EXPECTED THROUGH THE  
REMAINDER OF TONIGHT--CLEAR SKIES AND LIGHT TERRAIN DRIVEN WINDS.  
 
THE SURFACE GRADIENT TIGHTENS SIGNIFICANTLY ON TUESDAY PRODUCING  
STRONG EAST TO SOUTHEASTERLY FLOW. BREEZES PICK UP SHORTLY BEFORE  
SUNRISE ALONG THE NEW MEXICO BORDER, EXPANDING WESTWARD ACROSS THE  
FORECAST AREA DURING THE MORNING. CONDITIONS MAY APPROACH WIND  
ADVISORY CRITERIA IN SOME LOCALES FOR A BRIEF PERIOD OF TIME,  
ESPECIALLY IN THE TUCSON METRO AREA, BUT WILL NOT BE WIDESPREAD  
ENOUGH TO JUSTIFY ANY FURTHER ACTIONS.  
 
A FEW SLIGHT TWEAKS WERE MADE TO THE FORECAST THIS EVENING BASED ON  
THE LATEST GUIDANCE. HIGH TEMPERATURES WERE DROPPED 2-5 DEGREES FROM  
TUCSON EAST AND WINDS WERE BROUGHT UP A COUPLE KNOTS IN THE TUCSON  
METRO AREA. FOR DETAILS ON THE REMAINDER OF THE WEEK, PLEASE SEE THE  
PREVIOUS DISCUSSION BELOW.  
 

 
   
AVIATION
 
VALID THRU 25/06Z.  
CLEAR SKIES INTO TUESDAY EVENING. SURFACE WIND VARIABLE IN DIRECTION  
MAINLY LESS THAN 10 KTS THROUGH THE NIGHT, INCREASING ELY/SELY 10-25  
KTS WITH GUSTS TO 35 KTS BY AROUND 24/15Z, CONTINUING INTO TUESDAY  
EVENING. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.  
 

 
   
FIRE WEATHER
 
DRY CONDITIONS CONTINUE INTO EARLY NEXT WEEK.  
20-FOOT SUSTAINED WINDS TUESDAY MORNING INTO WEDNESDAY MORNING EAST  
TO SOUTHEAST 10-25 MPH WITH GUSTS TO NEAR 35 MPH. A FEW LOCATIONS IN  
FIRE WEATHER ZONE 151 MAY BRIEFLY REACH CRITICAL FIRE WEATHER  
THRESHOLDS LATE TUESDAY MORNING AND EARLY TUESDAY AFTERNOON. THE  
GUSTY EAST WINDS WILL DECREASE WEDNESDAY AFTERNOON. WINDS TURN WEST  
TO NORTHWEST THURSDAY AND FRIDAY AND BECOME BREEZY AGAIN, ESPECIALLY  
FOR AREAS EAST OF TUCSON.  
 

 
   
PREV DISCUSSION /227 PM MST/
 
AN UNSEASONABLY STRONG RIDGE OF HIGH  
PRESSURE WILL BRING RECORD HIGH TEMPERATURES TO THE AREA TODAY, WITH  
NEAR RECORD VALUES TUESDAY. WE'RE ON THE EASTERN FLANK OF THE RIDGE  
WITH A STRONG TROUGH DIGGING INTO MOST OF THE COUNTRY DOWNSTREAM.  
 
DRY CONDITIONS IN THE FLOW AROUND THE RIDGE WITH PRECIPITABLE WATER  
BETWEEN .2 AND .3 INCHES. SURFACE DEW POINTS ARE DOWN 8 TO 10  
DEGREES OVER THE PAST 24 HOURS, GENERALLY IN THE TEENS AND 20S.  
WE'LL SEE GUSTY EASTERLY WINDS DEVELOP TUESDAY AS A SURFACE HIGH  
BUILDS DOWN THE FRONT RANGE OF THE ROCKIES, BUT STILL NOT MUCH  
MOISTURE.  
 
HIGH PRESSURE WILL RETREAT INTO THE EASTERN PACIFIC AS THE TROUGH  
DEEPENS THROUGH MUCH OF THE REST OF THE COUNTRY. AS A RESULT OUR  
TEMPERATURES WILL GRADUALLY MODERATE OVER THE NEXT SEVERAL DAYS, BUT  
STILL REMAIN ABOVE AVERAGE. GUSTY WINDS DEVELOPING FRIDAY AS THE  
RIDGE TRIES TO NUDGE BACK IN FROM THE WEST AND A STUBBORN MEAN  
TROUGH POSITION REMAINS IMMEDIATELY DOWNSTREAM.  
 
NO PRECIP UNTIL FURTHER NOTICE.  
 

 
   
TWC WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
HOWLETT  
PREV DISCUSSION...MEYER  
 
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON  
 
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