190
FXUS65 KBOU 042059
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
259 PM MDT SUN MAY 4 2025
KEY MESSAGES
- SCATTERED SHOWERS AND A FEW THUNDERSTORMS OVER THE WESTERN HALF OF
THE CWA, MAINLY THIS EVENING.
- SPRING STORM FROM MONDAY AFTERNOON WELL INTO WEDNESDAY, WITH HEAVY
MOUNTAIN SNOWFALL POSSIBLE.
- UPPER RIDGING MOVES INTO THE FORECAST AREA ON THURSDAY AND
CONTINUE INTO THE WEEKEND.
SHORT TERM /THROUGH MONDAY/
ISSUED AT 213 PM MDT SUN MAY 4 2025
SATELLITE AND RADAR PICTURES ARE SHOWING DEVELOPING CONVECTION
MAINLY OVER THE MOUNTAINS AT THIS TIME. THERE IS EVEN A BIT OF
LIGHTNING. CELLS ARE MOVING TO THE NORTH-NORTHWESTWARD TODAY. THERE
IS 10 TO 25 KNOT SOUTHEASTERLY FLOW ACROSS THE PLAINS INTO THE LOWER
FOOTHILLS AT THIS TIME. WATER VAPOR SATELLITE PICTURES ARE SHOWING
AND UPPER CLOSED LOW OVER THE SOUTHERN CALIFORNIA BORDER WITH
MEXICO.
MODELS SHOW THE UPPER CLOSED LOW TO MOVE NORTHEASTWARD ACROSS
ARIZONA OVERNIGHT AND MONDAY TO BE OVER THE FOUR CORNERS BY 00Z LATE
MONDAY AFTERNOON. THE QG OMEGA FIELDS SHOW WEAK UPWARD VERTICAL
VELOCITY OVER THE CWA STARTING LATER TONIGHT CONTINUING THROUGH
MONDAY. MODEL CROSS SECTIONS AND SOUNDINGS SHOW A SIGNIFICANT
INCREASE IN MOISTURE FOR MOST THE CWA BY MONDAY AFTERNOON. THE QPF
FIELDS SHOW LIMITED PRECIPITATION THIS EVENING IN THE MOUNTAINS,
MORE SO SOUTH OF I-70. IT TAPPERS OFF AFTER 06Z. ON MONDAY, ALL
THE MODELS SHOW DECENT PRECIPITATION BY AFTERNOON ACROSS MUCH OF THE
CWA, THE MOST AFTER 21Z. THERE IS LIMITED CAPE PROGGED, MOSTLY OVER
THE WESTERN HALF OF THE CWA IN THE AFTERNOON. SNOW LEVEL ARE STILL
PRETTY HIGH MONDAY AFTERNOON; 10,000 FEET AT THE LOWEST. FOR
TEMPERATURES, MONDAY'S HIGHS LOOK ABOUT 10-15 DEGREES COOLER THAN
THIS AFTERNOON'S READINGS WITH THE INCREASED MOISTURE AND CLOUD
COVER EXPECTED.
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/
ISSUED AT 213 PM MDT SUN MAY 4 2025
GUIDANCE IS STILL IN GOOD AGREEMENT THAT THE BULK OF THE
PRECIPITATION FROM THIS INCOMING SYSTEM WILL FALL ON TUESDAY AND
TUESDAY NIGHT. HOWEVER, THERE ARE STILL A LOT OF INCONSISTENCIES
BETWEEN MODELS AND MODEL RUNS ON EXACT AMOUNT OF PRECIPITATION AND
PRECIP TYPE.
ENSEMBLE RUNS HAVE NOW HONED IN ON A MORE NORTHERLY TRACK OF THE
SYSTEM, WITH THE UPPER LEVEL CLOSED LOW REACHING NORTHERN NEW MEXICO
BY TUESDAY MORNING. AT THE SURFACE, THERE WILL BE CONSISTENT
SOUTHEASTERLY FLOW ADVECTING AMPLE MOISTURE INTO THE AREA, WITH
WIDESPREAD AND HEAVIER PRECIPITATION THROUGHOUT THE DAY. THE URBAN
CORRIDOR AND EASTERN SLOPES OF THE FRONT RANGE ARE STILL LIKELY TO
RECEIVE THE MOST PRECIPITATION (1-2" OF QPF), DUE TO THIS EVENT
BEING DRIVEN BY UPSLOPE FORCING. HOWEVER, RECENT RUNS HAVE TRENDED
TOWARDS HIGHER AMOUNTS, WITH THE CMCE AND EPS HINTING AT OVER 2" OF
QPF FOR THE HIGH COUNTRY. IN ADDITION, THERE ARE HUGE
INCONSISTENCIES WITH QPF AMOUNTS IN THE PLAINS WITH ENSEMBLE
GUIDANCE RANGING ANYWHERE FROM 0.5-1.5". AT THIS POINT, IT IS TOO
EARLY TO TELL EXACTLY WHERE THE GRADIENT OF MOISTURE WILL DROP OFF
FOR THE PLAINS. HOWEVER, WE ARE CERTAIN THAT THE EASTERN PLAINS WILL
RECEIVE LESS AMOUNTS THAN THE WESTERN PARTS.
IN TERMS OF PRECIPITATION TYPE, CONFIDENCE IS HIGH THAT AREAS ABOVE
9,000 FT. WILL RECEIVE ALMOST A FOOT OF SNOW, WITH THE HIGHEST
ELEVATIONS POSSIBLY SEEING CLOSE TO 2 FT. OF SNOW BY WEDNESDAY
MORNING. BECAUSE OF THIS, WE HAVE ISSUED A WINTER STORM WATCH FOR
THE FRONT RANGE MOUNTAINS MONDAY EVENING THROUGH WEDNESDAY MORNING.
IT IS MORE UNCLEAR IF THE ELEVATIONS BETWEEN 6,500-8,000 FT. WILL BE
DOMINATED BY RAIN OR SNOW, AS MODELS ARE STRUGGLING TO GRASP HOW
COLD TEMPERATURES WILL GET. SOME HIGHER RESOLUTION MODELS INDICATE
THE LOW PRESSURE SYSTEM PULLING IN COLDER 850-MB TEMPS FROM THE
NORTH, WHICH WOULD MEAN MORE SNOWFALL FOR THE FOOTHILLS AND PALMER
DIVIDE. HOWEVER, CONFIDENCE IS NOT HIGH ENOUGH THAT THIS WILL
VERIFY, SO HAVE HELD OFF ON ANY WINTER HIGHLIGHTS FOR THE LOWER
ELEVATIONS FOR NOW.
PRECIPITATION ACROSS THE REGION SHOULD LINGER THROUGH WEDNESDAY AS
THIS SYSTEM TRAVELS EAST. AN UPPER LEVEL RIDGE IS EXPECTED TO START
BUILDING OVER WESTERN UNITED STATES, WHICH WILL BRING ABOVE NORMAL
TEMPERATURES TOWARDS THE END OF THE WEEK AND INTO THE WEEKEND. ASIDE
FROM DAILY CHANCES FOR DIURNAL CONVECTIVE SHOWERS IN THE MOUNTAINS,
DRY CONDITIONS SHOULD PREVAIL.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1144 AM MDT SUN MAY 4 2025
WINDS ARE EXPECTED TO CONSISTENTLY COME FROM THE SOUTH/SOUTHEAST
THROUGH THE TAF PERIOD FOR KDEN AND KAPA WITH GUSTS UP TO 25-30 KTS
LIKELY INTO TOMORROW. VCSH OR VIRGA SHOWERS ARE POSSIBLE AROUND 02Z
WHICH COULD CAUSE STRONGER SOUTHERLY OUTFLOWS OF UP TO 35 KTS.
CEILINGS WILL START LOWERING TOMORROW AROUND 10Z WITH MVFR/IMC AND
SHOWERS DEVELOPING IN THE AREA AROUND 18Z.
BOU WATCHES/WARNINGS/ADVISORIES
WINTER STORM WATCH FROM MONDAY EVENING THROUGH LATE TUESDAY
NIGHT FOR COZ033-034.
SHORT TERM...RJK
LONG TERM....IDEKER
AVIATION.....IDEKER
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