209  
FXUS65 KPUB 180527  
AFDPUB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PUEBLO CO  
1027 PM MST SAT FEB 17 2018  
   
UPDATE
 
 
ISSUED AT 840 PM MST SAT FEB 17 2018  
 
WINDS A LITTLE SLOW TO INCREASE THIS EVENING, THOUGH HIGH MOUNTAIN  
PASS OBS WERE FINALLY BEGINNING TO TREND UPWARD AT 03Z. LATEST FEW  
RUNS OF THE HRRR SUGGEST STRONGEST WINDS MAY NOT OCCUR UNTIL AFTER  
SUNRISE ON SUN, WITH A PEAK IN MID TO LATE MORNING. WON'T CHANGE  
ANY HIGHLIGHTS AT THIS POINT, THOUGH MAY NEED TO DECREASE WIND  
SPEEDS SOMEWHAT OVERNIGHT IN THE NEXT UPDATE IF DOWNSLOPE FLOW  
CONTINUES TO BE SLOW TO DEVELOP.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH SUNDAY)  
ISSUED AT 353 PM MST SAT FEB 17 2018  
 
...HIGH WINDS TO RETURN FOR THE SOUTHEAST MOUNTAINS AND ADJACENT  
EASTERN SLOPES MAINLY WEST OF I-25...  
...CRITICAL FIRE WEATHER CONDITIONS EXPECTED FOR THE SOUTHEAST  
PLAINS AND LOWER SLOPES OF THE SOUTHEAST MOUNTAINS ON SUNDAY...  
 
CHALLENGE IN SHORT TERM IS HOW FAR DOWN THE SLOPES HIGH WINDS WILL  
PROGRESS AGAIN OVERNIGHT. WITH UPPER LOW DIGGING SOUTHWARD INTO THE  
PACIFIC NW TONIGHT, FLOW ALOFT SHIFTS TO A MORE WEST SOUTHWESTERLY  
COMPONENT. THIS IS A MORE FAVORABLE CROSS BARRIER FLOW FOR MUCH OF  
THE SOUTHEASTERN MOUNTAINS. HOWEVER VARIOUS HIGH RES MODELS HAVE  
DIFFERING SOLUTIONS ON THE DEVELOPMENT OF A MOUNTAIN WAVE AND HOW  
FAR DOWN THE SLOPES IT PROGRESSES. THE LOCAL 4 KM WRF AND 3KM NAM  
NEST SUGGESTS STRONG DOWNSLOPE WINDS WILL SPREAD FROM THE HIGHER  
PEAKS INTO PORTIONS OF THE I-25 CORRIDOR FROM LATE TONIGHT THROUGH  
SUNDAY MORNING...WHILE HRRR IS MORE CONSERVATIVE AND KEEPS WINDS  
CONFINED TO THE HIGHER PEAKS. MODEL CROSS-SECTIONS LOOK BEST ACROSS  
NORTHERN AREAS (EL PASO COUNTY) WITH A GOOD AMOUNT OF REVERSE SHEAR  
DEVELOPING TOWARDS MORNING THOUGH THERE ISN'T MUCH OF A MOUNTAIN TOP  
INVERSION. HOWEVER THERE DOESN'T NECESSARILY HAVE TO BE AS WE SAW  
LAST NIGHT AND MODELS ARE NOT GOOD AT HANDLING THESE DETAILS ANYWAY.  
LEANING ON VARIOUS HIGH RES MODELS HAVE UPGRADED THE HIGH WIND  
WATCH TO A WARNING, THOUGH WASN'T GETTING ENOUGH COVERAGE IN THE  
WEST CENTRAL PORTIONS OF LAS ANIMAS COUNTY TO WARRANT AN UPGRADE  
THERE. IN THE EL PASO COUNTY AREA...THINK FOCUS WILL SHIFT TO THE  
SOUTHWEST SIDE OF COLORADO SPRINGS AND FORT CARSON AREA TOWARDS DAWN  
GIVEN THE MORE SOUTHWESTERLY COMPONENT ALOFT. ANOTHER AREA TO WATCH  
WILL BE THE I-25 CORRIDOR SOUTH OF COLORADO CITY. THE WEST SIDE OF  
CUSTER COUNTY INTO THE WET MOUNTAIN VALLEY COULD ALSO SEE A PERIOD  
OF DAMAGING WINDS OVERNIGHT ACCORDING TO WRF AND NAMNEST. WILL KEEP  
OVERNIGHT LOWS ON THE WARM SIDE TO ACCOUNT FOR DOWNSLOPE WINDS WHICH  
ARE LIKELY TO CONTINUE OVERNIGHT TO AT LEAST SOME DEGREE ALONG/WEST  
OF I-25.  
 
FOR SUNDAY LOOKS LIKE MOUNTAIN WAVE PARAMETERS SHOULD BREAK DOWN BY  
LATE MORNING...THOUGH WINDS WILL REMAIN STRONG AS UPPER JET  
TRANSLATES IN ALOFT. SHOULD START TO SEE MOISTURE INCREASE ALONG  
THE CONTINENTAL DIVIDE DURING THE AFTERNOON WITH SNOW DEVELOPING  
DURING THE LATE AFTERNOON. MAIN BRUNT OF THE ACCUMULATIONS HOLDS  
OFF UNTIL LATER SUNDAY NIGHT. MEANWHILE...GUSTY WINDS WILL SPREAD  
INTO THE PLAINS DURING THE AFTERNOON. TEMPERATURES ACROSS THE  
PLAINS WILL WARM INTO THE 70S...WELL ABOVE NORMAL FOR THIS TIME OF  
YEAR, AND COMBINED WITH DRY SURFACE DEW POINTS WILL LEAD TO  
WIDESPREAD CRITICAL FIRE WEATHER CONDITIONS. HAVE UPGRADED THE FIRE  
WEATHER WATCHES TO RED FLAG WARNINGS. HAVE ADDED ZONE 225 TO  
ACCOUNT FOR THE LOWER EASTERN SLOPES ALONG THE I-25 INTERFACE AS  
WINDS WILL BE PARTICULARLY STRONG IN THIS AREA. -KT  
   
LONG TERM
 
(SUNDAY NIGHT THROUGH SATURDAY)  
ISSUED AT 353 PM MST SAT FEB 17 2018  
   
..WINDY WITH SNOW AND BLOWING SNOW ACROSS THE CONTDVD MONDAY
 
 
 
SUNDAY NIGHT-TUESDAY...CURRENT MODELS CONTINUE TO DIG THE PAC  
NORTHWEST SYSTEM INTO THE GREAT BASIN AND LIFT IT OUT ACROSS ROCKIES  
IN THE LATE SUNDAY NIGHT THROUGH TUESDAY TIMEFRAME, WITH ONLY SLIGHT  
DIFFERENCES IN TIMING. THE ECMWF STILL IS A TAD SLOWER WITH THIS  
SYSTEM, WHICH ALLOWS FOR SHALLOW COOL AIRMASS TO FILTER ACROSS THE  
EASTERN PLAINS THROUGH THE DAY MONDAY, WHERE AS THE GFS AND THE NAM  
SOLUTIONS KEEP THE COOLER AIR NORTH OF THE THE AREA WITH STRONG WEST  
TO SOUTHWEST FLOW IN PLACE ACROSS THE SOUTHEAST PLAINS.  
 
ALL SOLUTIONS POINT TO INCREASING SNOW ALONG AND WEST OF THE CONTDVD  
SUNDAY NIGHT, WITH SNOW LIKELY ACROSS THE CONTDVD MONDAY AND MONDAY  
NIGHT. WITH STRONG OROGRAPHIC SOUTHWEST WINDS OF 25 TO 50 MPH, HAVE  
UPGRADED WINTER STORM WATCH FOR THE EASTERN SAN JUAN MOUNTAINS TO A  
WARNING FROM 06Z MONDAY THROUGH 12Z TUESDAY. SNOW AMOUNT OF 8 TO 14  
INCHES ARE EXPECTED, WITH LOCALIZED AMOUNTS UP TO 20 INCHES POSSIBLE  
ON FAVORED SOUTHWEST PEAKS. WE HAVE ALSO ISSUED WINTER WEATHER  
ADVISORIES FOR LOWER RIO GRANDE VALLEY (3 TO 6 INCHES) AND FOR THE  
SAWATCH AND MOSQUITO RANGES (4 TO 8 INCHES, LOCALLY UP TO A FOOT)  
FOR THE SAME TIMEFRAME. STRONG AND GUSTY SOUTHWEST WINDS THROUGH THE  
DAY MONDAY BECOMES MORE WESTERLY MONDAY NIGHT AND TUESDAY, WITH  
DIFFICULT TRAVEL EXPECTED ACROSS THE HIGHER MOUNTAIN PASSES IN SNOW  
AND BLOWING SNOW.  
 
FURTHER EAST, THE INCREASING SOUTHWEST FLOW ALOFT WILL AGAIN LEAD TO  
POTENTIAL FOR STRONG DOWNSLOPE WINDS ACROSS THE SOUTHERN MOUNTAINS  
AND LOWER EASTERN SLOPES SUNDAY NIGHT INTO EARLY MONDAY MORNING,  
WITH MODEL CROSS-SECTIONS INDICATING A MEAN CRITICAL LAYER MAINLY  
ACROSS THE SOUTHERN SANGRE DE CRISTO MOUNTAINS. CURRENT GRIDS  
INDICATING GUSTS IN THE 60 TO 70 MPH RANGE ACROSS THIS AREA, AND  
LATER SHIFTS MAY NEED TO GO WITH WIND HIGHTLIGHTS. MONDAY  
TEMPERATURES AND WINDS ACROSS THE PLAINS ARE TRICKY AT THIS TIME,  
WITH ANOTHER BIG BUST POTENTIAL WITH A SHALLOW COLD AIRMASS MOVING  
ACROSS THE PLAINS. AS MENTIONED EARLIER, THE FASTER GFS AND NAM HAVE  
AN INDUCED SURFACE LOW ACROSS THE SOUTHEAST PLAINS MONDAY, KEEPING  
STRONG AND GUSTY WEST TO SOUTHWEST WINDS ACROSS THE I-25 CORRIDOR  
AND GUSTY SOUTHERLY WINDS ACROSS THE FAR EASTERN PLAINS, WHERE AS  
THE SLOWER EC SOLUTION HAS A WEAKER LOW NEAR TAD MONDAY MORNING,  
WHICH ALLOWS FOR SHALLOW COLD AIRMASS TO FILTER ACROSS THE PLAINS  
THROUGH THE DAY. HAVE TRIED TO BLEND TOWARDS THIS COOLER SOLUTION,  
WITH TEMPS IN THE 40S AND 50S ALONG AND NORTH OF THE HIGHWAY 50  
CORRIDOR MONDAY MORNING, WITH TEMPS THEN COOLING INTO THE AFTERNOON.  
IF THE GFS AND NAM SOLUTIONS ARE MORE CORRECT, THERE WILL BE  
POSSIBLE CRITICAL FIRE WEATHER CONDITIONS ACROSS MOST OF THE PLAINS  
ON MONDAY, WITH CURRENT GRIDS INDICATING POSSIBLE FIRE WEATHER  
HIGHLIGHTS FOR LAS ANIMAS COUNTY AND POSSIBLY SOUTHERN PORTIONS OF  
BACA COUNTY.  
 
BY MONDAY NIGHT, SNOW SPREADS ACROSS THE HIGH MOUNTAIN VALLEY AND  
INTO THE EASTERN MOUNTAINS, WITH GENERALLY LIGHT ACCUMULATIONS  
EXPECTED. SHALLOW COLD AIRMASS SPREADS ACROSS ALL OF THE SOUTHEAST  
PLAINS WITH STRATUS BANKED UP ACROSS THE LOWER EASTERN SLOPES,  
LEADING TO CHANCES OF LIGHT SNOW ACROSS THE I-25 CORRIDOR AND THE  
EASTERN PLAINS THROUGH THE DAY TUESDAY, WITH THE OVERRUNNING  
PATTERN. COOL UPSLOPE FLOW ACROSS THE PLAINS ON TUESDAY WILL KEEP  
HIGHS IN THE 20S AND 30S AREAWIDE.  
 
WEDNESDAY-SATURDAY...CONTINUED WEST TO SOUTHWEST FLOW ALOFT WILL  
LEAD TO A SLOW WARMING TREND ACROSS THE AREA THROUGH THE END OF THE  
WORK WEEK. DRY CONDITIONS LOOK TO RETURN TO EASTERN COLORADO, WITH  
LIGHT SNOW POSSIBLE ACROSS THE CONTDVD THROUGH THE PERIOD.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)  
ISSUED AT 1021 PM MST SAT FEB 17 2018  
 
VFR AT ALL TAF SITES THE NEXT 24 HRS. KCOS WILL SEE A RISK OF LLWS  
OVERNIGHT AS WINDS ALOFT INCREASE, BEFORE SURFACE WINDS INCREASE  
AND BECOME GUSTY BY MID-MORNING. ALL TERMINALS WILL SEE STRONG  
W-SW WINDS DURING THE DAY SUN, WITH GUSTS OVER 30 KTS LIKELY.  
 

 
   
PUB WATCHES/WARNINGS/ADVISORIES
 
 
RED FLAG WARNING FROM 10 AM TO 6 PM MST SUNDAY FOR COZ222-  
225>237.  
 
HIGH WIND WARNING UNTIL NOON MST SUNDAY FOR COZ072>075-078>082-  
084-085-087.  
 
WINTER WEATHER ADVISORY FROM 11 PM SUNDAY TO 5 AM MST TUESDAY  
FOR COZ058-060-061-065>067.  
 
WINTER STORM WARNING FROM 11 PM SUNDAY TO 5 AM MST TUESDAY FOR  
COZ068.  
 

 
 

 
 
UPDATE...EP  
SHORT TERM...KT  
LONG TERM...MW  
AVIATION...PETERSEN  
 
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