078
FXUS65 KBOU 051805
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1205 PM MDT MON MAY 5 2025
KEY MESSAGES
- SPRING STORM STARTS TODAY, WITH MAIN PEAK TUESDAY - TUESDAY
NIGHT, WINDING DOWN BY WEDNESDAY. HEAVY SNOW FOR THE FRONT RANGE
MOUNTAINS AND HIGHER FOOTHILLS ALMOST CERTAIN (80+% CHANCE).
SOAKING RAINS FOR LOWER ELEVATIONS, BUT UNCERTAINTY AS TO HOW
MUCH.
- WARMER WEATHER MOVES INTO THE FORECAST AREA ON THURSDAY AND
CONTINUES INTO THE WEEKEND. STILL A FEW LATE DAY SHOWERS AND
STORMS MOST DAYS.
PREVIOUS DISCUSSION THROUGH SUNDAY/
ISSUED AT 336 AM MDT MON MAY 5 2025
MAIN UPDATES IN THE SHORT TERM WERE FOR TIMING THE WAVES OF
PRECIPITATION. THE ONE FOR TODAY LOOKS SLIGHTLY DELAYED, AND
OVERALL IS NOT THAT IMPRESSIVE. THERE SHOULD STILL BE ENOUGH LIFT
IN THE LEFT EXIT REGION OF THE UPPER JET FOR MOST PLACES TO SEE
SHOWERS THIS AFTERNOON WITH A COUPLE EMBEDDED THUNDERSTORMS
(MLCAPE <300 J/KG), BUT QPF AMOUNTS OUTSIDE OF THE MOUNTAINS DON'T
LOOK THAT HIGH. WE'VE GENERALLY GONE WITH THE MODEL AVERAGES WITH
AROUND A TENTH OF AN INCH ON THE PLAINS, AND UPWARDS OF 0.25 TO
0.50 INCH FOR THE MOUNTAINS AND HIGHER FOOTHILLS THROUGH THIS
EVENING. WE THINK THERE WILL THEN BE A FAIR BREAK STARTING THIS
EVENING AND CONTINUING MOST OF THE NIGHT WITH LACK OF FORCING AND
DOWNSLOPE SOUTHERLY FLOW OFF THE PALMER DIVIDE. SPEAKING OF WHICH,
ANOTHER BREEZY/WINDY DAY FOR MOST OF THE PLAINS WITH
SOUTH/SOUTHEAST WINDS GUSTING TO 30-40 MPH.
THE MAIN STORM IS STILL ADVERTISED TO IMPACT OUR FORECAST AREA
STARTING TUESDAY MORNING AND CONTINUING THROUGH TUESDAY NIGHT.
THERE IS VERY GOOD AGREEMENT THAT WE'LL BE GETTING INTO MUCH
STRONGER LIFT AS ANOTHER PIECE OF ENERGY ROTATES OUT FROM THE
UPPER LEVEL LOW AS IT TRACKS NORTHEAST ACROSS NEW MEXICO TUESDAY
AND INTO THE OKLAHOMA PANHANDLE REGION BY TUESDAY NIGHT. WHILE
THERE'S GOOD AGREEMENT ON THIS TRACK, UPSLOPE, AND ADVECTION OF
GULF MOISTURE INTO THE FRONT RANGE, LATENT HEAT RELEASE FROM
CONVECTION IN TEXAS COULD STILL BE A WILDCARD THAT AFFECTS THE
TRACK AND AMOUNT OF SYNOPTIC SCALE LIFT. IT WAS INTERESTING TO
NOTE YESTERDAY'S 12Z ENSEMBLES ALL BEEFED UP QPF NUMBERS FOR THE
FRONT RANGE, WHILE THE MOST RECENT 00Z DROPPED IT A BIT AGAIN. WE
STILL THINK WE'LL HAVE A GOOD SHOT OF 1.25-1.5+" OF RAIN ACROSS
THE I-25 CORRIDOR, AND LOCALLY 2+" LIQUID EQUIVALENT IN THE
FOOTHILLS AND HIGHER EAST FACING SLOPES OF THE FRONT RANGE GIVEN
THE HIGH IVT, DEEP UPSLOPE COMPONENT, AND ANOMALOUSLY HIGH PW.
THAT MEANS HIGH CONFIDENCE WE'LL SEE WINTER STORM CRITERIA HIT IN
THE HIGHER FRONT RANGE MOUNTAINS LIKE THE INDIAN PEAKS, ROCKY
MOUNTAIN NATIONAL PARK, AND I-70 LEADING UP TO THE EISENHOWER
TUNNEL. WE DID SHAVE BACK THE START TIME OF THE WINTER STORM WATCH
TO TUESDAY MORNING, AS TODAY'S SNOW WILL BE MOSTLY AT OR ABOVE
PASS LEVEL WITH CONSIDERABLE MELTING ON HIGHER ELEVATION ROADS
WHERE IT DOES SNOW. THAT WILL CHANGE TOMORROW.
WE ARE ALSO CONCERNED ABOUT POTENTIALLY HEAVIER SNOW IN THE
FOOTHILLS ABOVE 7,500-8,000 FEET TUESDAY AFTERNOON AND NIGHT GIVEN
THE RECENT COOLING IN THE GEFS AND NAM GUIDANCE. HOWEVER, THE EPS
HAS REMAINED FAIRLY STEADY. IN ANY CASE, WE THINK SNOW LEVELS BY
TUESDAY AFTERNOON COULD BE DROPPING TO ~7,500 FEET, AND A LITTLE
LOWER THAN THAT TUESDAY NIGHT. AS A RESULT, WE HAVE COOLED
TEMPERATURES, LOWERED SNOW LEVELS A BIT MORE, AND BEEFED UP SNOW
TOTALS IN THE HIGHER FOOTHILLS WITH MOST PLACES ABOVE 8,000 FEET
EXPECTED TO SEE 8-12" OF SNOW. DESPITE WARM ROAD TEMPERATURES,
TRAVEL IMPACTS WILL ALSO BE POSSIBLE DOWN TO ABOUT THAT LEVEL OR
EVEN LOWER SHOULD SOME OF THE COLDER SOLUTIONS VERIFY, AS HEAVIER
SNOW WITH HIGH LIQUID WATER CONTENT MEANS ROAD TEMPS MAY NOT KEEP
UP WITH MELTING. WE THINK THE FOOTHILLS COULD VERY EASILY END UP
WITH A WINTER WEATHER ADVISORY FOR THIS EVENT TUESDAY THROUGH
TUESDAY NIGHT, WITH SOME POTENTIAL FOR WARNING (30-40%) SHOULD
SOME OF THE HIGHER QPF AND COLDER SOLUTIONS BECOME MORE LIKELY.
NO SIGNIFICANT CHANGES MADE BEYOND WEDNESDAY, WITH GENERALLY
WARMER AND DRIER WEATHER EXPECTED. WE STILL EXPECT ISOLATED TO
SCATTERED LATE DAY SHOWERS AND STORMS, WITH THE HIGHEST COVERAGE
OVER THE MOUNTAINS.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1200 PM MDT MON MAY 5 2025
MODELS HAVE SOUTH-SOUTHEASTERLY WINDS FOR DIA FROM 20-35 KNOTS
THROUGH THE AFTERNOON HOURS. THE SOUTHEASTERLIES LOOK TO CONTINUE
OVERNIGHT INTO TUESDAY, BUT AT LOWER SPEEDS. CURRENT RADAR &
SATELLITE PICTURES, ALONG WITH MODEL DATA POINT TO A CHANCE OF MID
AFTERNOON TO EARLY EVENING -TSRA. WILL GO WITH A PROB30 FOR NOW
AS MODELS SEEM TO BE TRENDING A BIT DRIER IN THE SHORT TERM. WILL
KEEP THINGS PRETTY DRY OVERNIGHT. CEILINGS ARE EXPECTED TO BE IN
THE BKN-OVC012-030 RANGE ALL NIGHT. WILL BRING IN THE WIDESPREAD
RAIN AFTER DAWN TUESDAY MORNING ALONG WITH IFR CONDITIONS.
BOU WATCHES/WARNINGS/ADVISORIES
WINTER STORM WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
NIGHT FOR COZ033-034.
PREVIUOS...BARJENBRUCH
AVIATION...RJK
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page