972  
FXUS65 KPUB 131021  
AFDPUB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PUEBLO CO  
421 AM MDT TUE APR 13 2021  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 420 AM MDT TUE APR 13 2021  
 
...MODERATE SNOW FOR THE CENTRAL MOUNTAINS THIS AFTERNOON AND  
TONIGHT WITH SOME SLUSHY ACCUMULATIONS DOWN TO 6000 FEET FOR THE  
ADJACENT LOWER ELEVATIONS ROUGHLY ALONG/NORTH OF HIGHWAY 50  
TONIGHT...  
 
UPPER LOW CARVING OUT AND DROPPING SOUTHWARD ACROSS THE PACIFIC  
NORTHWEST WILL SEND AN IMPULSE ACROSS CO AHEAD OF IT IN  
SOUTHWESTERLY FLOW ALOFT. THIS WILL SPREAD A ROUND OF SNOW INTO THE  
CENTRAL AND SOUTHEAST MOUNTAINS AND UPPER ARKANSAS RIVER VALLEY AS  
AREA OF WAA/OVERRUNNING SPREADS OVERTOP SHALLOW EASTERLY UPSLOPE  
FLOW. SNOW BEGINS ACROSS THE CENTRAL MOUNTAINS THIS MORNING, BUT  
PICKS UP IN EARNEST THIS AFTERNOON AS IT SPREADS SOUTHEASTWARD TO  
ENCOMPASS THE NORTHERN SANGRES/WETS AND PIKES PEAK REGION THIS  
EVENING. HEAVIEST ACCUMULATIONS STILL LOOK TO IMPACT THE SAWATCH AND  
MOSQUITO RANGES, INITIALLY ACROSS THE HIGHER ELEVATIONS BY EARLY  
AFTERNOON, THEN SPREADING INTO THE LOWER ELEVATIONS LATE THIS  
AFTERNOON AND EVENING AS SNOW LEVELS DROP. GETTING AROUND 4 TO 8  
INCHES OF ACCUMULATION ACROSS THIS AREA AS WELL AS THE NORTHERN  
SANGRE DE CRISTO MOUNTAINS, AND WILL HOIST ADVISORIES ACCORDINGLY  
WHICH WILL RUN THROUGH TONIGHT. GETTING LESSER AMOUNTS IN THE LOWER  
ARKANSAS RIVER VALLEY AND WITH RESIDUAL WARMTH IN THE GROUND  
CONTRIBUTING TO MELTING ON PAVEMENT SURFACES WILL REFRAIN FROM  
ADDING THESE AREAS IN AS THIS SHOULD MITIGATE ACCUMULATIONS SOME. IT  
IS A LITTLE TRICKIER PROPOSITION FOR THE LEADVILLE AREA WHERE WE  
COULD SEE A PERIOD OF MODERATE SNOW THIS EVENING WHICH COULD STACK  
UP TO LOW END ADVISORY VALUES. HAVE OPTED TO LEAVE THIS AREA OUT  
FOR NOW AS SNOWFALL AMOUNTS ARE COMING UP ON THE SHY SIDE WITH  
AROUND 2 TO 5 INCHES. IT APPEARS HEAVIER QPF STAYS TO THE SOUTH  
ACROSS CHAFFEE COUNTY WHERE UPSLOPE PENETRATING UP THE ARKANSAS  
RIVER VALLEY APPEARS TO ENHANCE PRECIPITATION TOTALS.  
 
SNOW WILL ALSO SPREAD INTO THE PIKES PEAK AND WET MOUNTAINS THIS  
EVENING WITH SNOW LEVELS DROPPING TO AROUND 6000 FEET BY MORNING.  
COULD SEE A SLUSHY INCH OR TWO ACROSS THE PALMER DIVIDE, BUT AGAIN  
THE WARM GROUND SHOULD MITIGATE IMPACTS TO TRAVEL. GETTING LESSER  
AMOUNTS FOR TELLER COUNTY THOUGH THE TOP OF PIKES PEAK COULD SEE  
AROUND 5 INCHES WITH A SIMILAR SCENARIO FOR THE WETS. THE SOUTHERN  
SANGRE DE CRISTO MOUNTAINS GET LESS FROM THIS EVENT WITH THE BEST  
LIFT/UPSLOPE COMBO STAYING FARTHER NORTH. EASTERN SAN JUANS AND LA  
GARITAS COULD SEE AROUND 1 TO 4 INCHES WITH A PERIOD OF UPSLOPE  
SPREADING IN LATE THIS AFTERNOON AND EVENING, BUT DRY SLOT CUTS BACK  
SNOW ACCUMULATION POTENTIAL PRETTY QUICKLY THIS EVENING. FOR THE  
SOUTHEAST PLAINS, SHOWERS WILL BE MORE ISOLATED IN COVERAGE WITH THE  
POTENTIAL FOR A RAIN/SNOW MIX DOWN TO 5000 FEET TOWARDS MORNING.  
LITTLE TO NO ACCUMULATION IS EXPECTED AND EVEN QPF AMOUNTS WILL BE  
LIGHT WITH GENERALLY A TRACE TO A HUNDREDTH OR TWO POSSIBLE.  
 
THERE IS STILL A LOW END POTENTIAL FOR FREEZING DRIZZLE TOWARDS 12Z  
WED AS THE DRY SLOT MOVES IN AND SHALLOW SATURATION CONTINUES ALONG  
THE SOUTHERN SLOPES OF THE PALMER DIVIDE IN SOUTHERLY UPSLOPE. STILL  
A VARIETY OF SOLUTIONS AS TO HOW QUICKLY SKIES CLEAR AND LOW LEVELS  
DRY OUT SO CONFIDENCE IS STILL LOW IN THIS OCCURING. IF IT DOES,  
IMPACTS SHOULD BE MINIMAL DUE TO RESIDUAL WARMTH OF THE GROUND.  
 
OTHERWISE, CONTINUED COOL TODAY WITH BELOW NORMAL TEMPERATURES FOR  
MOST OF THE AREA EXCEPT THE SAN LUIS VALLEY WHERE NEAR NORMAL  
TEMPERATURES ARE EXPECTED. -KT  
   
LONG TERM
 
(WEDNESDAY THROUGH MONDAY)  
ISSUED AT 420 AM MDT TUE APR 13 2021  
 
WEDNESDAY...  
 
AS THE UPPER WAVE EMBEDDED WITHIN THE SOUTHWEST FLOW ALOFT  
PROPAGATES TO THE NORTH AROUND THE MAIN UPPER LOW PARKED OVER THE  
GREAT BASIN, DRIER AIR IS ANTICIPATED TO INFILTRATE THE REGION.  
BECAUSE OF THE DRIER PUSH OF AIR INTO THE REGION, A LULL IN THE  
SHOWER ACTIVITY IS EXPECTED INTO THE AFTERNOON. THERE IS PRETTY GOOD  
AGREEMENT AMONGST THE MODEL GUIDANCE INDICATING THAT THE MAIN UPPER  
LOW BEGINS TO SLOWLY PUSH TO THE EAST, WHICH IS ANTICIPATED TO BRING  
AN UPTICK IN THE SHOWER ACTIVITY TO THE CENTRAL AND EASTERN  
MOUNTAINS, PALMER DIVIDE, AND TELLER COUNTY DURING THE AFTERNOON,  
WITH THE POTENTIAL FOR SOME ISOLATED TO SCATTERED SHOWERS REACHING  
THE I-25 CORRIDOR WEDNESDAY NIGHT. SNOW LEVELS LOOK TO BE RATHER  
HIGH IN THE 6500-7000 FEET RANGE IN THE AFTERNOON AND EVENING. SNOW  
AMOUNTS ARE GENERALLY EXPECTED TO BE RATHER LIGHT WITH THE CENTRAL  
MOUNTAINS POSSIBLY RECEIVING AN INCH OR SO OF ACCUMULATION, WHILE  
OTHER LOCATIONS ARE FORECAST TO SEE LESS THAN AN INCH AT THIS TIME.  
THEREFORE, IMPACTS ARE EXPECTED TO BE MINIMAL WITH THIS SHOT OF SNOW  
SHOWERS.  
 
ELSEWHERE, IN THE SAN LUIS VALLEY, RELATIVELY WARM TEMPERATURES,  
LOWER HUMIDITY VALUES AND GUSTY SOUTHWEST WINDS ARE ANTICIPATED TO  
CREATE NEAR CRITICAL FIRE WEATHER CONDITIONS IN THE AFTERNOON, WITH  
SOME SPOTTY CRITICAL CONDITIONS POSSIBLE WITHIN THE VALLEY. WITH THE  
SPOTTY NATURE OF THE CRITICAL FIRE WEATHER CONDITIONS, DECIDED NOT  
TO ISSUE ANY FIRE WEATHER WATCHES AT THIS TIME, BUT WILL CONTINUE TO  
MONITOR THE LATEST TRENDS FOR THE NEED OF ANY HIGHLIGHTS IN UPCOMING  
PACKAGES.  
 
THURSDAY AND FRIDAY...  
 
LATEST MODEL GUIDANCE CONTINUES TO INDICATE THAT THERE IS SOME  
UNCERTAINTY WITH HOW THE UPPER LOW TRACKS AS IT PROPAGATES EASTWARD.  
THE ECMWF SOLUTION CONTINUES TO TAKE IT ON A MORE NORTHERLY TRACK,  
WHILE THE NAM AND GFS TAKE IT A BIT FURTHER SOUTH. LOOKING AT SOME  
ENSEMBLE SOLUTIONS, THE EPS AND GEFS FOLLOW SIMILAR TRENDS AS THEIR  
DETERMINISTIC COUNTERPARTS, ECMWF AND GFS, RESPECTIVELY. A QUICK  
LOOK AT THE SREF OUTPUT SHOWS A NORTHERLY TRACK SIMILAR TO THE  
ECMWF AND EPS. THAT SAID, SCATTERED SHOWERS LOOK POSSIBLE ALONG AND  
EAST OF THE CENTRAL AND EASTERN MOUNTAINS THURSDAY INTO FRIDAY WITH  
THESE CHANCES SPREADING TO THE CONTINENTAL DIVIDE ON FRIDAY ON THE  
BACK SIDE OF THE SYSTEM. IF THE SYSTEM TAKES A MORE SOUTHERLY  
TRACK LIKE THE GFS AND NAM SUGGEST, A BETTER CHANCE FOR SHOWERS  
BECOMES POSSIBLE. SNOW LEVELS DO REMAIN RATHER HIGH ON THURSDAY, BUT  
THEN DROP TO AROUND 5000 FEET OR SO ON FRIDAY. MEANWHILE, ANOTHER  
DAY OF NEAR CRITICAL TO CRITICAL FIRE WEATHER CONDITONS ARE POSSIBLE  
OVER THE SAN LUIS VALLEY ON THURSDAY. MODELS DO AGREE THAT A COLD  
FRONT MOVES THROUGH THE AREA EARLY ON FRIDAY, WITH THE ECMWF MOVING  
IT THROUGH A BIT LATER THAN THE GFS, WHICH IS ANTICIPATED TO KEEP  
AFTERNOON HIGHS ON THE COOLER SIDE.  
 
SATURDAY INTO MONDAY...  
 
AS THE UPPER SYSTEM MOVES OUT OF THE AREA BY THE WEEKEND, A LAGGING  
TROUGH IS ANTICIPATED TO REMAIN OVER THE REGION FOR THE WEEKEND,  
BRINGING ADDITIONAL CHANCES FOR SHOWERS TO THE MOUNTAINS.  
HOWEVER, THERE IS QUITE A BIT OF UNCERTAINTY BETWEEN THE MODELS, SO  
CONFIDENCE REMAINS LOW ON THE FORECAST AT THIS TIME. OTHERWISE,  
DRIER AIR AND A WARMING TREND ARE ANTICIPATED TO MOVE BACK INTO THE  
AREA THROUGH THE WEEKEND INTO EARLY NEXT WEEK.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)  
ISSUED AT 420 AM MDT TUE APR 13 2021  
 
VFR CIGS WILL PERSIST THROUGH THE DAY AT ALL THREE TERMINALS WITH  
BREEZY EAST TO SOUTHEAST WINDS AT 10-20 KTS AT KCOS AND KPUB AND  
BREEZY SOUTHWESTERLY WINDS AROUND 10-20 KTS AT KALS DURING THE  
AFTERNOON. CEILINGS WILL DROP INTO THE MFVR TO IFR CATEGORY AT KCOS  
THIS EVENING AS SHOWERS SPREAD IN AFTER 00Z. COULD SEE A RAIN/SNOW  
MIX AT THE TERMINAL AROUND 03Z WITH UP TO AN INCH OF SLUSHY SNOW  
ACCUMULATION RESTRICTED TO THE GRASS POSSIBLE OVERNIGHT. KPUB IS  
MORE LIKELY TO STAY VFR TO MVFR WITH SOME BRIEF LIGHT -SHRA  
POSSIBLE. CEILINGS WILL LIFT INTO THE MVFR TO VFR CATEGORY FOR BOTH  
TERMINALS WED MORNING. KALS COULD SEE A BRIEF WINDOW OF MVFR CIGS  
WITH -SHRA THIS EVENING BEFORE RETURNING TO VFR. -KT  
 

 
   
PUB WATCHES/WARNINGS/ADVISORIES
 
 
WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 6 AM MDT  
WEDNESDAY FOR COZ060.  
 
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM MDT  
WEDNESDAY FOR COZ058-061-063-073.  
 

 
 

 
 
SHORT TERM...KT  
LONG TERM...CARLBERG  
AVIATION...KT  
 
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