966  
FXUS65 KGJT 172345  
AFDGJT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND JUNCTION CO  
445 PM MST SUN FEB 17 2019  
   
SHORT TERM
 
(TONIGHT THROUGH MONDAY NIGHT)  
ISSUED AT 1237 PM MST SUN FEB 17 2019  
 
CONVECTIVE CLOUD COVER HAS DEVELOPED OVER MUCH OF SOUTHWEST  
COLORADO AND SOUTHEAST UTAH THIS AFTERNOON AHEAD OF OUR NEXT STORM  
SYSTEM. GOES SATELLITE IMAGERY DEPICTS THE FIRST PIECE OF THIS  
SYSTEM WELL - A TROUGH WITH COOLER CLOUD TOPS DRAPED FROM  
NORTHWEST TO SOUTHEAST OVER UTAH. THE MAIN EVENT WITH THIS SYSTEM  
STILL REMAINS WELL TO THE WEST, CURRENTLY LOCATED OVER CENTRAL  
CALIFORNIA AND MOVING TO THE EAST INTO THE GREAT BASIN. WHILE A  
FEW ISOLATED SNOW SHOWERS MAY FALL IN THE HIGHER TERRAIN OF THE  
SAN JUANS THIS AFTERNOON, ANY PRECIPITATION WILL REMAIN LIGHT AND  
ACCUMULATIONS ARE NOT EXPECTED UNTIL AFTER 6PM.  
 
FORECAST GUIDANCE REMAINS ON TRACK THROUGHOUT THE SHORT TERM AND  
FORECAST CONFIDENCE IS HIGH. A LONG-DURATION, LIGHT TO MODERATE  
SNOWFALL RATE EVENT IS IN THE WORKS FOR CENTRAL AND SOUTHERN  
COLORADO AND UTAH. WHILE FIRST WAVE OF THIS SYSTEM IS NOT  
EXPECTED TO PRODUCE HEAVY SNOWFALL TONIGHT INTO MONDAY MORNING,  
THE STORY CHANGES A BIT ON MONDAY AFTERNOON. AS THE SECOND, MAIN  
TROUGH SPIRALS INTO THE FOUR CORNERS REGION, DIFFLUENT FLOW ALOFT  
WILL SUPPORT A PERIOD OF BETTER SNOWFALL RATES, ARRIVING AROUND  
3PM MONDAY IN SOUTHWEST COLORADO. UNLIKE SOME OF OUR RECENT  
STORMS, THIS EVENT LACKS A STRONG PACIFIC MOISTURE  
CONNECTION...HOWEVER A PERIOD OF FAVORABLE DYNAMICS ALOFT COMBINED  
WITH UPSLOPE FLOW WILL OVERCOME THE LACKLUSTER MOISTURE FEED.  
ADDITIONALLY, COLD TEMPERATURES IN PLACE THROUGHOUT THE ENTIRE  
FOUR CORNERS REGION WILL SUPPORT AN ALL-SNOW EVENT IN ALL  
LOCATIONS. SNOW-TO-LIQUID RATIOS ARE EXPECTED TO BE NEARLY DOUBLE  
WHAT WAS SEEN IN THE LAST EVENT, SOMEWHERE IN THE 15:1 RANGE OR  
HIGHER, ESPECIALLY ABOVE 8000 FEET. WITH ALL THAT BEING SAID, NO  
CHANGES WERE MADE TO EXPECTED SNOWFALL ACCUMULATIONS OR CURRENT  
HEADLINES THIS AFTERNOON. A FOOT OR MORE OF SNOW IS EXPECTED IN  
THE SAN JUANS, WITH 6-12 INCHES LIKELY IN THE SOUTHERN VALLEYS  
FORM DURANGO TO PAGOSA SPRINGS. THE LA SAL AND ABAJO RANGES IN  
SOUTHEAST UTAH SHOULD SEE 10 OR MORE INCHES AS WELL - ESPECIALLY  
GIVEN THE COMPARATIVELY LIGHTER SOUTHWEST FLOW ALOFT THAT USUALLY  
RESULTS IN BETTER TOTALS IN THESE RANGES. FARTHER NORTH, THERE IS  
SLIGHTLY LESS CONFIDENCE IN THE SNOWFALL FORECAST. THE GRAND MESA,  
ELK, SAWATCH AND GORE RANGES WILL BE DOWNRANGE OF THE SAN JUANS  
FOR MUCH OF THE EVENT WITH REGARD TO WIND AND MOISTURE FLOW. THE  
SAN JUANS WILL LIKELY RING OUT MUCH OF THE AVAILABLE LIQUID, AND  
KEEP SNOW TOTALS AROUND 6 INCHES OR LESS ON AVERAGE IN THESE  
CENTRAL MOUNTAIN ZONES. THEREFORE, HIGHLIGHTS WERE NOT ISSUED FOR  
THIS EVENT HERE.  
 
BY MONDAY NIGHT INTO TUESDAY MORNING, THE BEST SUPPORT FOR LIFT  
AND HIGHER SNOW RATES MOVES EAST OF THE CONTINENTAL DIVIDE. SNOW  
WILL BEGIN TO TAPER OFF IN INTENSITY AFTER MIDNIGHT, HOWEVER LIGHT  
SNOW ACCUMULATIONS WILL STILL BE SEEN THROUGHOUT WESTERN COLORADO.  
   
LONG TERM
 
(TUESDAY THROUGH SUNDAY)  
ISSUED AT 1237 PM MST SUN FEB 17 2019  
 
THE ONGOING WINTER STORM WILL SLOWLY MOVE EAST OF THE ROCKIES ON  
TUESDAY. LIGHT UPSLOPE WESTERLY FLOW WILL RESULT IN CONTINUED SNOW  
SHOWERS THROUGHOUT THE DAY, AND WITH COLD AIR IN PLACE (700MB  
TEMPS IN THE -14 TO -16 RANGE), EXCELLENT DENDRITIC GROWTH WILL  
LIKELY RESULT IN ADDITIONAL ACCUMULATIONS. THIS WILL BE ESPECIALLY  
TRUE WHERE CLOUD COVER REMAINS THICKER AND SURFACES CAN AVOID  
HEATING FROM THE MID-FEBRUARY SUN ANGLE. HOWEVER BY 6PM, THE  
ATMOSPHERIC COLUMN REALLY DRIES OUT FROM TOP TO BOTTOM AND SNOW  
SHOWERS ARE EXPECTED TO DIMINISH THROUGH THE EVENING.  
 
THE ACTIVE WEATHER PATTERN THAT HAS CHARACTERIZED THIS WINTER  
SEASON WILL CONTINUE THROUGH THE END OF THE LONG TERM. ANOTHER  
WINTER STORM WILL MOVE IN FROM WEDNESDAY NIGHT THROUGH FRIDAY.  
SOME DIFFERENCES IN FORECAST GUIDANCE REMAIN WITH THIS EVENT, WITH  
THE GFS FAVORING A MORE CUT-OFF AND FARTHER SOUTH LOW PRESSURE  
SYSTEM ON THURSDAY AND FRIDAY. THE ECMWF IS FARTHER NORTH  
INITIALLY, BUT EVENTUALLY COMES INTO LINE WITH THE GFS BY EARLY  
FRIDAY MORNING. TEMPERATURES LOOK TO REMAIN QUITE COLD WITH THIS  
SYSTEM, AND ANOTHER HEALTHY DUMP OF SNOW IS BECOMING MORE LIKELY  
FOR THE MOUNTAINS. THE SAN JUANS APPEAR FAVORED ONCE AGAIN WITH  
THIS SYSTEM, AND CURRENT GUIDANCE AVERAGES WOULD LIKELY SUPPORT  
ANOTHER FOOT OF SNOW HERE.  
 
BY FRIDAY EVENING, THIS SYSTEM WINDS DOWN AND HEADS EAST. AN EARLY  
LOOK AT THE WEEKEND REVEALS FAIRLY DRY WEATHER AND WESTERLY FLOW.  
HOWEVER, BY SUNDAY NIGHT FASTER WESTERLY FLOW IN THE PACIFIC  
NORTHWEST WILL DIP SOUTHWARD. MOISTURE ASSOCIATED WITH THIS  
FASTER FLOW CURRENTLY APPEARS TOO FAR NORTH TO IMPACT THE UINTA  
AND PARK RANGES. WE WILL SEE IF THIS SYSTEM TRENDS SOUTHWARD WITH  
TIME.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)  
ISSUED AT 445 PM MST SUN FEB 17 2019  
 
A DISTURBANCE IN SOUTHWEST SNOW WAS BRINGING SCATTERED SNOW  
SHOWERS TO AREAS OF SOUTHEAST UTAH WITH MORE SCATTERED ACTIVITY  
OVER SOUTHWEST AND PORTIONS OF CENTRAL COLORADO. THIS DISTURBANCE  
BRINGS A GOOD CHANCE FOR BRIEF MVFR CONDITIONS AT KCNY, KGJT AND  
KMTJ THIS EVENING. KTEX AND KDRO HAVE BETTER CHANCES FOR SNOW  
SHOWERS WITH SIMILAR CONDITIONS. AFTER A LULL LATER TONIGHT, SNOW  
IS EXPECTED TO BECOME WIDESPREAD OVER SOUTHWEST COLORADO WITH MVFR  
AND PERIODS OF IFR CONDITIONS LIKELY AT KDRO AND KTEX. ELSEWHERE,  
KRIL, KEGE AND KASE WILL EXPERIENCE PROLONGED PERIODS WITH CIGS  
BELOW ILS BREAKPOINTS WITH LOW END CHANCES FOR LIGHT SNOW.  
 

 
   
GJT WATCHES/WARNINGS/ADVISORIES
 
 
CO...WINTER STORM WARNING UNTIL 6 PM MST TUESDAY FOR COZ018-019.  
 
WINTER WEATHER ADVISORY UNTIL 6 PM MST TUESDAY FOR COZ017-020-  
021.  
 
WINTER STORM WARNING UNTIL 6 PM MST TUESDAY FOR COZ022-023.  
 
UT...WINTER STORM WARNING UNTIL 6 PM MST TUESDAY FOR UTZ028.  
 

 
 

 
 
SHORT TERM...MAC  
LONG TERM...MAC  
AVIATION...NL  
 
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