436  
FXUS65 KBOU 272207  
AFDBOU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DENVER/BOULDER CO  
407 PM MDT MON MAR 27 2017  
   
SHORT TERM
 
(THIS EVENING THROUGH TUESDAY)  
ISSUED AT 407 PM MDT MON MAR 27 2017  
 
SOUTHWEST FLOW ALOFT WILL BE OVER THE AREA THROUGH TOMORROW  
MORNING WITH THE INCOMING TROUGH CONTINUING TO PROGRESS SE OVER  
THE GREAT BASIN. BY 12Z TOMORROW BOTH THE GFS AND EC HAVE THE LOW  
CENTER PROGRESSIVELY FURTHER SOUTH ALONG WITH THE THE CANADIAN AND  
NAM SOLUTIONS. AHEAD OF THE MAIN TROUGH THE MOISTURE WILL CONTINUE  
TO INCREASE OVER THE WESTERN PORTIONS OF THE STATE AND INTO THE  
HIGHER TERRAIN BRINGING RAIN AND SNOW STARTING THIS EVENING.  
COOLER AIR WILL MOVE INTO THE MOUNTAINS ALONG WITH DECENT QG LIFT  
THAT WILL ALLOW FOR THE SNOW LEVEL TO DROP DOWN TO 8500 FT BY  
TUESDAY MORNING AND CONTINUE TO LOWER THROUGH WEDNESDAY MORNING.  
CURRENT FORECAST ACCUMULATIONS HAVE POSSIBLE 6 TO 12 INCHES FOR  
THE HIGHER TERRAIN WITH THE MOST ABOVE 7000 FT AND OVER THE  
CENTRAL MOUNTAINS SOUTH OF I-70. BY TUESDAY MORNING THE MODELS  
SHOW THE UPPER LOW MOVING EASTWARD ACROSS NEW MEXICO INCREASING  
SSE FLOW ON THE PLAINS TURNING MORE EASTERLY BY TUESDAY AFTERNOON  
AND EVENING. THIS INITIAL SE FLOW AND INCREASING LEE TROUGH WILL  
DRY SLOT CLOSER TO THE FOOTHILLS DELAYING THE ONSET OF  
PRECIPITATION UNTIL LATER IN THE AFTERNOON/EVENING TUESDAY FOR  
AREAS WEST OF I-25. BY LATE TUESDAY MODELS HAVE SURFACE WINDS  
SWITCHING TO A MORE NE DIRECTION AS THE LOW MOVES SOUTH.  
TEMPERATURES WILL COOL TOMORROW WITH HIGHS IN THE UPPER 40S TO  
LOWER 50S WITH SOME AREAS DROPPING INTO THE 30S AS PRECIPITATION  
DEVELOPS.  
   
LONG TERM
 
(TUESDAY NIGHT THROUGH MONDAY)  
ISSUED AT 407 PM MDT MON MAR 27 2017  
 
DEEP MOISTURE AND LIFT WILL MOVE OVER TUESDAY NIGHT INTO  
WEDNESDAY. MODELS HAVE CONSOLIDATED ON A TRACK THAT KEEPS THE  
BEST LIFT WILL BE ACROSS SOUTHERN COLORADO, WITH MODERATE LIFT AS  
FAR NORTH AS INTERSTATE 76, AND LESS FURTHER NORTH. BLENDED MODEL  
QPF LOOKS REASONABLE WITH AMOUNTS OF ONE- HALF TO ONE INCH PLUS A  
BIT MORE FOR MODEST UPSLOPE ENHANCEMENT IN THE SOUTHERN FOOTHILLS.  
BIG QUESTION REMAINS THE TEMPERATURES. TREND HERE IS ALSO  
RELATIVELY WARM, SUGGESTING A SHARP GRADIENT IN SNOWFALL AT AROUND  
6000 FEET. IT MAY BE COLD ENOUGH FOR SOME SNOW IN DENVER WEDNESDAY  
MORNING, BUT AT ELEVATIONS BETWEEN 5 AND 6 THOUSAND FEET THERE  
SHOULD BE A MIX OF RAIN AND SNOW AND AIR AND GROUND TEMPERATURES  
STAYING ABOVE FREEZING WILL LIMIT THE IMPACT. WOULD NOT BE  
SURPRISED TO SEE SOME OF THESE AREAS GET A COUPLE INCHES OF SNOW  
ON THE GRASS AND MAYBE A LITTLE SLUSH ON THE ROADS AT RUSH HOUR,  
BUT PROBABLY NOT ENOUGH FOR BIG PROBLEMS. HIGHER ELEVATIONS SHOULD  
SEE A PERIOD OF HEAVIER SNOW DURING THE LATE NIGHT UNTIL ABOUT  
RUSH HOUR. PUTTING TOGETHER THE PRECIPITATION AND TEMPERATURE  
PATTERNS LEAVES US WITH NEEDING A WINTER STORM WATCH FOR AREAS  
WEST AND SOUTH OF DENVER, WHILE OTHER AREAS ARE EXPECTING MUCH  
LESS OR NO SNOWFALL. WE MAY NEED TO LOOK AT AN ADVISORY FOR OTHER  
MOUNTAIN AREAS, BUT THE UPSLOPE ENHANCEMENT SHOULD LIMIT THE HEAVY  
SNOW TO THE WATCH AREAS.  
 
THIS STORM WILL BE MOVING OUT SLOWLY ON WEDNESDAY, WITH  
TEMPERATURES RECOVERING FAIRLY WELL AS THERE IS NO COLD AIR MASS  
COMING IN ITS WAKE. THERE WILL BE A BREAK THURSDAY WITH WARMING  
SOUTHERLY LOW LEVEL FLOW ON THE PLAINS, THEN A LITTLE MOISTURE AND  
INSTABILITY ARRIVES AHEAD OF THE NEXT SYSTEM THAT COULD BRING SOME  
LIGHT SHOWERS TO THE MOUNTAINS LATE THURSDAY.  
 
THERE IS REASONABLE AGREEMENT ON THE NEXT SYSTEM FOR FRIDAY AND  
SATURDAY. AGAIN THE DETAILS OF PLACEMENT AND TEMPERATURE WILL BE  
IMPORTANT, BUT IT DOES LOOK LIKE A PRETTY GOOD CHANCE OF  
SIGNIFICANT PRECIPITATION AGAIN, AND WITH TEMPERATURES SIMILAR TO  
THE TUESDAY NIGHT/WEDNESDAY STORM. THERE ARE SOME MODEL RUNS THAT  
ARE A FEW DEGREES COOLER, WHICH COULD MAKE A DIFFERENCE FOR  
DENVER, BUT THERE ISN'T ANYTHING TO POINT AT A MORE WIDESPREAD  
SIGNIFICANT SNOW. CONSENSUS NOW SEEMS TO BE ABOUT THE SAME WITH  
TEMPERATURES DROPPING INTO THE LOWER 30S IN DENVER AND SIGNIFICANT  
SNOW STARTING SOMEWHERE BETWEEN 5,000 AND 6,500 FEET.  
 
ONCE AGAIN, THERE IS NO COLD AIR BEHIND THE FRIDAY/SATURDAY SYSTEM  
SO WE SHOULD WARM RIGHT BACK UP AGAIN. THERE IS SOME DIVERGENCE IN  
THE MODELS AFTER THIS. MOST KEEP A STRING OF STRONG SYSTEMS MOVING  
THROUGH EVERY TWO OR THREE DAYS. AGAIN, MOSTLY WARM, THOUGH A FEW  
DEW TAP SOME SLIGHTLY COLDER AIR AND COULD POSE A THREAT OF SNOW  
IN THE MIDDLE OF NEXT WEEK. THE LATEST OPERATIONAL ECMWF IS AN  
OUTLIER BUILDING A BROADER RIDGE FOR MILD AND DRY WEATHER IN THE  
EARLY PART OF NEXT WEEK. IN ANY EVENT, THAT NEXT SYSTEM DOES NOT  
APPEAR TO COME BEFORE NEXT MONDAY NIGHT, SO MILD AND DRIER IN THE  
MEANTIME.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)  
ISSUED AT 407 PM MDT MON MAR 27 2017  
 
VFR CONDITIONS ARE EXPECTED THROUGH 11Z TOMORROW AS THE NEXT  
WEATHER DISTURBANCE MOVES INTO THE AREA. MID LEVEL MOISTURE WILL  
INCREASE BY THIS EVENING DROPPING THE CEILING TO 060 WITH LIGHT  
RAIN POSSIBLE BETWEEN 01 AND 05Z. THE PROGRESS OF THE LOW WILL  
ALLOW FOR A DRY SLOT TO SET UP HELPING TO DECREASE PRECIPITATION  
CHANCES BETWEEN 11 AND 20Z...HOWEVER LOW LEVEL MOISTURE WILL MOVE  
IN AS WINDS TRANSITION TO WESTERLY THEN NORTH BRINGING IN IFR  
CEILINGS BY 11Z. RAIN WILL PICK UP SHORTLY AFTER THE ONSET OF THE  
NORTHERLY WINDS BY 21Z WITH SOME GUSTING UP TO 20 MPH. HAVE HIGH  
CONFIDENCE THAT THE PRECIPITATION WILL REMAIN LIQUID AT THE DENVER  
TERMINAL THROUGH TUESDAY EVENING WITH TEMPERATURES BEING TOO HIGH  
FOR SNOW.  
 

 
   
BOU WATCHES/WARNINGS/ADVISORIES
 
 
WINTER STORM WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY  
MORNING FOR COZ036.  
 
WINTER STORM WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY  
MORNING FOR COZ041.  
 

 
 

 
 
SHORT TERM...BOWEN  
LONG TERM...GIMMESTAD  
AVIATION...BOWEN  
 
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