362  
FXUS65 KBOU 260020  
AFDBOU  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DENVER/BOULDER CO  
620 PM MDT THU APR 25 2019  
   
UPDATE
 
 
ISSUED AT 619 PM MDT THU APR 25 2019  
 
MADE MINOR ISSUES TO TIMING OF TOMORROW'S SHOWERS/STORMS FORMING  
OVER THE HIGHER TERRAIN AND PUSHING OFF OVER THE PLAINS. MAY NEED  
TO BUMP UP WINDSPEEDS MOVING OFF THE FOOTHILLS TOMORROW LATE  
AFTERNOON AS THE CONVECTION PUSHES OVER THE URBAN CORRIDOR IN THE  
DRY ENVIRONMENT. CURRENT FORECAST HAS GUSTS IN THE 15-20 MPH  
RANGE, HOWEVER LOOKING AT THE INVERTED-V FORECAST SOUNDINGS AND  
THE SHORT RANGE HI RES MODELED WIND GUSTS, MAY SEE CLOSER TO 30-40  
MPH. WILL MONITOR MODEL CONSISTENCY AND CONFIDENCE.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY)  
ISSUED AT 119 PM MDT THU APR 25 2019  
 
A STRONG FRONTAL PUSH EARLY THIS MORNING BROUGHT MORNING CLOUDS THAT  
DISSIPATED INTO MOSTLY SUNNY SKIES ACROSS THE REGION. OVERALL,  
CONDITIONS REMAIN TOO STABLE OVER THE PLAINS FOR ANY CONVECTION  
TODAY, HOWEVER, SATELLITE SHOWS SOME CU DEVELOPING OVER THE HIGHER  
TERRAIN AS LAPS CAPE VALUES INCREASE INTO THE 200 TO 500 J/KG RANGE.  
THIS WILL HELP TO BRING ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS  
TO THE MOUNTAINS INTO THE LATE AFTERNOON HOURS. MAIN HAZARDS WILL BE  
LIGHT RAIN AND GUSTY WINDS. AT LOWER ELEVATIONS, SOME GUSTING WILL  
CONTINUE OVER THE FAR EASTERN PLAINS THROUGH INTO THE EARLY EVENING  
WITH GUSTS UP TO 25 MPH. FOR THIS EVENING, TEMPERATURES WILL DROP  
INTO THE LOWER TO MID 40S ACROSS THE PLAINS AND 20S TO 30S OVER THE  
MOUNTAINS AND FOOTHILLS.  
 
FOR FRIDAY, UPPER LEVEL FLOW WILL BE FROM THE WNW WITH A SURFACE LOW  
IN PLACE OVER THE NORTHERN FOOTHILLS. THIS SURFACE LOW WILL TRACK SE  
ACROSS THE NORTHERN PLAINS THROUGH THE AFTERNOON HOURS PULLING SW  
WINDS OVER THE PLAINS. THIS INITIAL NW FLOW AT THE SURFACE WILL  
INTRODUCE DRYING IN THE LOWER LEVELS ACROSS THE PLAINS. LATER INTO  
THE AFTERNOON MODELS ARE SHOWING INCREASED INSTABILITY WITH CAPE  
VALUES RANGING FROM 200 TO 800 J/KG. THIS WILL BE ENOUGH FOR  
SCATTERED THUNDERSTORMS, BUT WITH DRY LOW LEVELS EXPECT SOME  
LIGHT RAIN BUT MOSTLY GUSTY WINDS TO ACCOMPANY THE STORMS.  
COVERAGE FOR STORMS WILL BE HIGHER OVER THE MOUNTAINS ON FRIDAY  
WITH SHOWERS, GUSTY WINDS AND SOME LIGHTNING POSSIBLE.  
TEMPERATURES WILL REBOUND FROM THE FRONTAL PASSAGE TODAY WITH  
HIGHS BACK INTO THE 70S OVER THE PLAINS AND 50S IN THE MOUNTAINS.  
   
LONG TERM
 
(FRIDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 119 PM MDT THU APR 25 2019  
 
FRIDAY NIGHT, THERE WILL BE WEAK MID LEVEL QG ASCENT OVER  
THE AREA IN THE EVENING THEN STRONG SUBSIDENCE DEVELOPS AS A  
STORM SYSTEM EXITS INTO THE FROM WYOMING INTO NEBRASKA. THE MODELS  
SHOW A STRONG WEST/NORTHWEST WIND COMPONENT 50-60 KTS FRIDAY  
NIGHT. MOISTURE DEPTH WILL BE DECREASING AFTER 06Z UNDER  
INCREASING SUBSIDENCE. MOUNTAINS SHOULD SEE SOME LIGHT SNOW  
ACCUMULATIONS OF 2 TO 5 INCHES ABOVE TIMBERLINE. ACROSS THE  
NORTHEAST PLAINS, ISOLATED TO SCATTERED HIGH BASED THUNDERSTORMS  
IN THE EVENING, THEN JUST ISOLATED SHOWERS. STRONG OUTFLOW WINDS  
WOULD BE THE BIGGEST THREAT FROM THE STORMS.  
 
SATURDAY AND SATURDAY NIGHT, A DRIER BUT FAIRLY BRISK NORTHWESTERLY  
FLOW ALOFT WILL REMAIN OVER THE AREA. GUSTY WINDS WILL CONTINUE IN  
THE MOUNTAINS WITH JUST SOME LINGERING SHOWERS IN THE MORNING.  
ACROSS THE NORTHEAST PLAINS, NOT AS WARM AS FRIDAY BUT STILL ABOVE  
NORMAL. THE MODELS SHOW GUSTY SOUTH/SOUTHEAST WINDS DEVELOPING  
LATE IN THE DAY. BY 00Z SUNDAY, THERE MAY BE MUST ENOUGH CAPE  
(200-400 J/KG) OVER THE PALMER DIVIDE TO POP A BRIEF THUNDERSTORM  
BUT THAT MAY BE IT.  
 
SUNDAY AND SUNDAY NIGHT, AN INCREASING ZONAL FLOW ALOFT AS A  
SYSTEM PASSES WELL TO THE NORTH THROUGH MONTANA. ENOUGH MID LEVEL  
MOISTURE AROUND COUPLED WITH DAYTIME HEATING FOR SCATTERED SHOWERS  
AND THUNDERSTORMS IN THE MOUNTAINS, WITH THE SNOW LEVEL JUST  
ABOVE 10 THOUSAND FEET, WITH ISOLATED TO SCATTERED SHOWERS AND  
THUNDERSTORMS OVER THE PLAINS IN THE AFTERNOON AND EVENING. A COLD  
FRONT DOES PUSH INTO NORTHEAST COLORADO FROM THE NORTH IN THE  
EVENING, WHICH WILL HELP ACT AS A FOCUSING MECHANISM FOR THE  
THUNDERSTORMS. IN ADDITION, THE RIGHT ENTRANCE REGION OF JET MAX  
PASSING THROUGH WYOMING AROUND 06Z SUNDAY NIGHT, WHICH WOULD HELP  
ENHANCE THE PRECIPITATION ESPECIALLY IN THE MOUNTAINS, MAYBE  
ENOUGH TO PRODUCE A FEW INCHES OF SNOW IN THE HIGHER MOUNTAINS.  
BY 12Z MONDAY, A SUBTROPICAL JET WILL SPREAD FROM THE DESERT  
SOUTHWEST INTO CENTRAL COLORADO AHEAD OF THE NEXT SYSTEM.  
 
MONDAY AND TUESDAY WILL BE COOLER AND MORE UNSETTLED WITH A BETTER  
CHANCE OF PRECIPITATION ACROSS THE CWA. UNCERTAINTY STILL EXISTS  
IN REGARDS TO THE TIMING, WITH THE GFS FASTER VS THE ECMWF WITH  
THE NEXT SYSTEM. OVERALL, IT APPEARS TO BE FAIRLY WET DURING THIS  
PERIOD. THE GFS IS STILL GENERATING HIGHER QPF THAN THE ECMWF. IN  
TERMS OF PRECIPITATION TYPE, SNOW SHOWERS IN THE MOUNTAINS, MORE  
OF A MIX IN THE FOOTHILLS AND PALMER DIVIDE. ACROSS THE PLAINS,  
PRECIPITATION TYPE MAY BE MORE OF A MIX IN THE MORNING WITH RAIN  
SHOWERS IN THE AFTERNOON. STILL NOT SURE WHEN THE BEST PERIOD FOR  
PRECIPITATION WOULD BE, BUT MONDAY AFTERNOON INTO TUESDAY MORNING  
LOOKS LIKE BEST COMPROMISE AT THIS POINT AS THE UPPER TROUGH  
LIFTS OUT OF THE DESERT SOUTHWEST AND ACROSS COLORADO. WEDNESDAY  
WILL BE A LITTLE WARMER, BUT STILL UNSETTLED WITH A CHANCE OF  
SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND EVENING.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY AFTERNOON)  
ISSUED AT 619 PM MDT THU APR 25 2019  
 
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. EASTERLY WINDS  
ARE EXPECTED TO VEER TO DRAINAGE BY LATE THIS EVENING WITH SPEEDS  
STAYING BETWEEN 6 TO 12 KTS. ISOLATED TO SCATTERED AFTERNOON  
CONVECTION TOMORROW AFTERNOON TO MOVE EAST OFF THE HIGHER TERRAIN  
AFTER 19Z, WITH CONDITIONS MORE FAVORABLE AFTER 21Z AT KDEN. WITH  
A DRY ENVIRONMENT AND STRONG WINDS ALOFT, THE CONVECTION MAY BE  
ACCOMPANIED WITH GUSTS IN THE 25 TO 35 KT RANGE.  
 

 
   
BOU WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
UPDATE...KRIEDERMAN  
SHORT TERM...BOWEN  
LONG TERM...COOPER  
AVIATION...KRIEDERMAN  
 
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