271  
FXUS65 KGJT 170221  
AFDGJT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND JUNCTION CO  
821 PM MDT TUE JUL 16 2019  
   
UPDATE
 
 
ISSUED AT 817 PM MDT TUE JUL 16 2019  
 
UPDATED TO REMOVE EXPIRE RED FLAG HEADLINE. CRITICAL FIRE WEATHER  
CONDITIONS WILL REDEVELOP WEDNESDAY AFTERNOON AND EVENING ACROSS  
MOST OF EASTERN UT AND WESTERN CO.  
 

 
   
SHORT TERM
 
(TONIGHT THROUGH WEDNESDAY NIGHT)  
ISSUED AT 339 PM MDT TUE JUL 16 2019  
 
THUNDERSTORM COVERAGE WAS A BIT FURTHER WEST THAN MODELS INDICATED  
AS THE MODELS SEEM TO BE HAVING A TOUGH TIME HANDLING THE REMNANT  
MOISTURE AND DRYING THINGS OUT TOO QUICKLY. THE FOCUS FOR ACTIVITY  
APPEARS TO BE SHIFTING EASTWARD LATE THIS AFTERNOON WITH THE FOCUS  
SHIFTING TOWARDS THE SAN JUANS AND WEST ELKS BY THIS EVENING.  
EXPECT MOST ACTIVITY TO END AFTER SUNSET. THE HRRR AND TO SOME  
EXTENT NAMNEST IS SHOWING SOME ISOLATED THUNDERSTORMS MOVING IN  
FROM THE SOUTH ACROSS THE SOUTHERN VALLEYS AND SAN JUANS LATE THIS  
EVENING INTO THE EARLY MORNING HOURS ON WEDNESDAY. PRECIPITABLE  
WATER (PW) VALUES, ALTHOUGH THEY ARE DECREASING ACROSS MUCH OF THE  
AREA, DO SHOW A BUMP UP ABOVE 0.75 TOWARDS AN INCH IN THIS REGION  
OVERNIGHT. MODELS HAD A VERY HARD TIME PICKING UP ON THE OVERNIGHT  
CONVECTION LAST NIGHT, SO AM LEANING TOWARDS THIS OCCURRING.  
INCREASED POPS IN THIS AREA OVERNIGHT WITH ACTIVITY DISSIPATING  
BY SUNRISE.  
 
MUCH DRIER AIR MOVES IN FOR WEDNESDAY AS PW VALUES DROP BELOW 0.5.  
THE GRADIENT TIGHTENS A BIT WITH BETTER MIXING AS AN UPPER LEVEL  
TROUGH SWINGS ACROSS THE REGION. ENOUGH PW REMAINS NEAR THE FOUR  
CORNERS FOR ISOLATED STORMS POSSIBLE OVER THE SAN JUANS WEDNESDAY  
AFTERNOON, BUT FOR THE MOST PART, EXPECT ANOTHER HOT AND DRY DAY  
WITH CRITICAL FIRE WEATHER CONDITIONS EXPANDING TO INCLUDE ALL  
LOWER ELEVATIONS OF EASTERN UTAH AND WESTERN COLORADO. UPGRADED  
THE FIRE WEATHER WATCH FOR REMAINING VALLEY ZONES TO A RED FLAG  
WARNING FOR WEDNESDAY AND EXPANDED IT TO INCLUDE THE UINTA BASIN  
ZONE AS IT LOOKS CRITERIA WILL BE MET THERE AS WELL.  
   
LONG TERM
 
(THURSDAY THROUGH TUESDAY)  
ISSUED AT 339 PM MDT TUE JUL 16 2019  
 
A MUCH DRIER WESTERLY FLOW WILL FOLLOW BEHIND THE TROUGH PASSAGE  
WEDNESDAY, WITH WARM AND DRY CONDITIONS REMAINING THROUGH THE END  
OF THE WEEK. THINKING THIS TROUGH WILL ACT TO FINALLY PUSH THE  
LINGERING MOISTURE OUT OF THE REGION. SOME BREEZY CONDITIONS MAY  
OCCUR DURING THE AFTERNOONS WITH POTENTIAL FOR CRITICAL FIRE  
WEATHER CONDITIONS, ESPECIALLY ACROSS THE NORTHERN ZONES THAT  
REMAIN IN CLOSER PROXIMITY TO THE UPPER LEVEL JET. DECIDED NOT TO  
ISSUE ANY FIRE WEATHER WATCH FOR THURSDAY YET WITH THE RED FLAG  
WARNING ONGOING FOR BOTH TODAY AND WEDNESDAY, AS CONDITIONS APPEAR  
MARGINAL AT THIS TIME, BUT SOMETHING FOR LATER SHIFTS TO REASSESS.  
 
AN UPPER LEVEL TROUGH WILL MOVE ACROSS THE NORTHERN ROCKIES, NEAR  
CANADA ON FRIDAY, ALLOWING THE RIDGE OF HIGH PRESSURE TO BUILD  
BACK OVER THE REGION BY THE WEEKEND. THIS WILL ALSO ALLOW MORE  
MOISTURE TO ENTER THE REGION FROM THE SOUTHWEST AS PW VALUES  
INCREASE ABOVE 0.75 INCHES ON SATURDAY AND ABOVE AN INCH BY EARLY  
NEXT WEEK. THIS WILL INCREASE THUNDERSTORM POTENTIAL AND COVERAGE  
WITH BETTER CHANCES FOR WETTING RAIN BY EARLY NEXT WEEK. THE ONE  
CONCERN WITH THIS MOISTURE SURGE IS THE POSITION OF THE HIGH AS IT  
IS DIRECTLY OVERHEAD AS OPPOSED TO THE MORE FAVORABLE EAST OF THE  
DIVIDE POSITIONING. THE EC SEEMS TO HAVE COME AROUND TO AGREEMENT  
WITH THE GFS ON THE MORE WESTERLY POSITION. SO, THE MONSOONAL  
MOISTURE AXIS WILL BE FORCED THROUGH NEW MEXICO AND ARIZONA, INTO  
NEVADA AND WESTERN UTAH. WE WILL STILL SEE SOME MOISTURE INCREASE,  
BUT IT MAY NOT BE AS ROBUST OR WIDESPREAD WITH STORM COVERAGE AS  
REMNANTS OF THAT MOISTURE PLUME WILL GET ENTRAINED AND RECYCLED  
AROUND THE HIGH. REGARDLESS, LOOK FOR AN INCREASE IN SHOWERS AND  
THUNDERSTORMS THIS WEEKEND TOWARDS EARLY NEXT WEEK WITH CONTINUED  
ABOVE NORMAL TEMPERATURES.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)  
ISSUED AT 459 PM MDT TUE JUL 16 2019  
 
EXPECT BREEZY SOUTHWEST WINDS FROM 10 TO 15 MPH AT MOST TAF SITES  
THROUGH EARLY THIS EVENING WITH OCCASIONAL GUSTS AS HIGH AS 30 MPH.  
ISOLATED SHOWERS AND THUNDERSTORMS WILL OCCUR MAINLY OVER THE  
HIGHER TERRAIN WITH LITTLE CHANCE FOR TAF SITES TO BE IMPACTED BY  
RAIN, THOUGH STRONG AND UNPREDICTABLE OUTFLOW WINDS TO 40 MPH ARE  
POSSIBLE. SHOWERS AND THUNDERSTORMS WILL DIMINISH BEFORE MIDNIGHT.  
FEWER THUNDERSTORMS ARE EXPECTED WEDNESDAY AFTERNOON.  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 817 PM MDT TUE JUL 16 2019  
 
DRY, BREEZY AND HOT CONDITIONS ARE EXPECTED TO REDEVELOP WEDNESDAY  
AFTERNOON AND BRING A REPEAT OF CRITICAL FIRE WEATHER CONDITIONS  
OVER MUCH OF EASTERN UT AND WESTERN CO. HOT AND DRY CONDITIONS  
WILL CONTINUE THROUGH THE END OF THE WEEK WITH SOME BREEZES DURING  
THE AFTERNOONS. SUNDAY BRINGS THE FIRST CHANCE OF RAIN WITH  
CHANCES INCREASING A BIT EACH DAY NEXT WEEK.  
 

 
   
GJT WATCHES/WARNINGS/ADVISORIES
 
 
CO...RED FLAG WARNING FROM NOON TO 8 PM MDT WEDNESDAY FOR COZ200-202-  
203-207-290-292.  
 
UT...RED FLAG WARNING FROM NOON TO 8 PM MDT WEDNESDAY FOR UTZ486-487-  
490-491.  
 

 
 

 
 
UPDATE...CC  
SHORT TERM...MDA  
LONG TERM...MDA  
AVIATION...CC  
FIRE WEATHER...CC  
 
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