851  
FXUS65 KGJT 142347  
AFDGJT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND JUNCTION CO  
447 PM MST THU DEC 14 2017  
   
SHORT TERM
 
(TONIGHT THROUGH FRIDAY NIGHT)  
ISSUED AT 318 PM MST THU DEC 14 2017  
 
SOME LIGHT SNOW AND CLOUDS ARE STILL LINGERING ALONG THE DIVIDE  
WITH MOSTLY SUNNY SKIES TO THE WEST AND IMPROVING CONDITIONS IN  
MOST AREAS. EXPECT THIS LIGHT SNOW AND CLOUD COVER TO CLEAR LATE  
THIS AFTERNOON INTO THE EVENING AS A DRIER, NORTHERLY FLOW  
CONTINUES TO MOVE IN BEHIND THIS DISTURBANCE. THE RIDGE OF HIGH  
PRESSURE STILL SITS FIRMLY TO THE WEST BUT SHOWS SIGNS OF BREAKING  
DOWN THIS WEEKEND INTO THE COMING WEEK. MORE ON THAT IN THE LONG  
TERM SECTION. A TROUGH OF LOW PRESSURE CRASHES INTO THE RIDGE ON  
FRIDAY OVER THE PACIFIC NORTHWEST AND WILL CAUSE THE RIDGE TO  
SLIDE EASTWARD, AS THIS SYSTEM DIVES INTO THE GREAT BASIN.  
INVERSIONS ARE EXPECTED TO RETURN IN THE VALLEYS ON FRIDAY AS THIS  
RIDGE SLIDES BACK OVER THE AREA, RESULTING IN SLIGHTLY COOLER, YET  
STILL ABOVE NORMAL TEMPERATURES.  
   
LONG TERM
 
(SATURDAY THROUGH THURSDAY)  
ISSUED AT 318 PM MST THU DEC 14 2017  
 
THE AFOREMENTIONED TROUGH WILL MOVE THROUGH THE REGION SATURDAY  
EVENING THROUGH SUNDAY, WITH JET ENERGY DIVING SOUTH OF THE FOUR  
CORNERS. THIS WILL KEEP THE BETTER PRECIPITATION ACROSS ARIZONA  
AND NEW MEXICO, BUT THE MOUNTAINS AND HIGH VALLEYS OF EASTERN UTAH  
AND WESTERN COLORADO STILL STAND A CHANCE TO SEE SOME SNOWFALL IN  
THE REALM OF 2 TO 4 INCHES AS THIS SYSTEM MOVES THROUGH FAIRLY  
QUICK AND DOESN'T BRING A LOT OF MOISTURE WITH IT. THE NAM12  
APPEARS THE WETTEST SOLUTION, WHEREAS THE GFS, EC AND CANADIAN ARE  
A BIT DRIER. LEANING MORE TOWARDS THE DRIER AND MORE PROGRESSIVE  
SOLUTION. NORTHWEST FLOW BEHIND THIS SYSTEM LOOKS TO CONTINUE  
LIGHT OROGRAPHIC SNOW OVER THE ELKHEADS AND NORTHERN PARK RANGE  
MONDAY AND TUESDAY, SO KEPT SLIGHT CHANCE IN THERE.  
 
A MORE PROGRESSIVE PATTERN LOOKS TO FINALLY TAKE SHAPE AS YET  
ANOTHER TROUGH OF LOW PRESSURE MOVES INTO THE PACIFIC NORTHWEST  
LATE TUESDAY AND ACROSS THE NORTHERN ROCKIES BY WEDNESDAY. THE  
MODELS ARE IN GENERAL AGREEMENT ON TIMING WITH THIS SYSTEM MOVING  
THROUGH OUR AREA WEDNESDAY EVENING THROUGH THURSDAY. THE  
DIFFERENCES LIE IN THE DETAILS BEYOND THURSDAY MORNING, WHERE THE  
EC AND CANADIAN FAVOR A MORE PROGRESSIVE SOLUTION WITH A 110 KT  
JET ORIENTED NW TO SE, HELPING TO PUSH THIS SYSTEM THROUGH FAIRLY  
QUICKLY AND BRING MUCH DRIER AIR IN BY THURSDAY AFTERNOON,  
EFFECTIVELY SHUTTING DOWN PRECIPITATION. THE GFS SEEMS TO BE THE  
OUTLIER WITH THE JET ENERGY DIVING NORTH TO SOUTH DOWN TO MEXICO,  
WHICH CAUSES THE SYSTEM TO FORM A CLOSED LOW OVER SOUTHERN  
CALIFORNIA AND KEEP OUR AREA IN A DEFORMATION ZONE, WHICH KEEPS  
PRECIPITATION ONGOING THROUGH FRIDAY MORNING. DESPITE THESE  
DIFFERENCES, THE MODELS ARE IN AGREEMENT ON MUCH COLDER AIR  
ARRIVING WITH THIS SYSTEM, IN THE REALM OF -12C (SOUTH) TO -20C  
(NORTH)...COLD ENOUGH TO SNOW IN ALL AREAS. JUST HOW MUCH SNOW  
REMAINS TO BE SEEN DEPENDING ON HOW THE DETAILS WORK THEMSELVES  
OUT. HIGH CONFIDENCE REMAINS THROUGH WEDNESDAY BUT TAKES A  
NOSEDIVE TO LOW CONFIDENCE BY THURSDAY DUE TO MODEL  
DISCREPANCIES.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)  
ISSUED AT 439 PM MST THU DEC 14 2017  
 
POST FRONTAL AIRMASS WILL REMAIN QUITE MOIST IN A FEW SPOTS, MOST  
NOTABLY ASE, WHERE ILS BREAK POINTS HAVE BEEN REACHED WITH  
LINGERING STRATUS. THE REST OF THE AREA SHOULD SEE CLEARING  
THROUGH THE EVENING WITH ONLY SOME HIGH CIRRUS MOVING IN  
OVERNIGHT. WINDS WILL BE MOSTLY LIGHT AND TERRAIN DRIVEN WITH THE  
EXCEPTION OF SOME GUSTS AT TEX, WHICH SHOULD BEGIN TO DIE DOWN  
AFTER SUNSET. TEMPORARY HIGH PRESSURE BUILDING IN SHOULD ALLOW  
VFR CONDITIONS TO DEVELOP FOR ALL TERMINALS BY MID MORNING  
TOMORROW.  
 

 
   
GJT WATCHES/WARNINGS/ADVISORIES
 
 
CO...NONE.  
UT...NONE.  

 
 

 
 
SHORT TERM...MDA  
LONG TERM...MDA  
AVIATION...ADL  
 
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