974
FXUS65 KBOU 140530
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1130 PM MDT SUN APR 13 2025
KEY MESSAGES
- SCATTERED RAIN AND SNOW SHOWERS OVERNIGHT. WATCHING THE
POTENTIAL FOR A SHORT-LIVED BAND OF SNOW LATER TONIGHT ACROSS
THE DENVER METRO.
- TEMPERATURES COOL MORE FOR MONDAY.
- WARMER TEMPERATURES EXPECTED TUESDAY THROUGH MIDWEEK.
- ACTIVE WEATHER PATTERN ON TRACK TO END THE WEEK, WITH POTENTIAL FOR
MOUNTAIN SNOW AND WIDESPREAD LOWER ELEVATION PRECIPITATION.
UPDATE
ISSUED AT 854 PM MDT SUN APR 13 2025
SHOWERS THIS EVENING HAVE BEEN A LITTLE BIT NORTH OF EXPECTED...
CLOSER TO A FNL-GXY-FMM LINE... WITH GENERALLY DRY CONDITIONS
ACROSS THE DENVER METRO. THESE SHOWERS APPEAR TO BE PRIMARILY
DRIVEN BY THE NOW-DEPARTING UPPER LEVEL JET STREAK OVER FAR
NORTHEAST COLORADO, AND IT WOULDN'T BE SURPRISING TO SEE A FEW
HOUR LONG BREAK ACROSS MOST OF THE I-25 CORRIDOR THROUGH THE REST
OF THE EVENING HOURS.
HOWEVER, THERE STILL LOOKS TO BE A GOOD CHANCE OF PRECIPITATION
OVERNIGHT, AS THE SECOND JET STREAK DEVELOPS ACROSS CENTRAL
COLORADO, PLACING THE DENVER METRO BACK IN THE FAVORABLE LEFT EXIT
REGION. EARLY 00Z GUIDANCE IS IN GOOD AGREEMENT DEVELOPING A
NARROW BAND OF PRECIPITATION - INITIALLY RAIN AND SNOW, TURNING TO
ALL SNOW - FROM A LITTLE AFTER MIDNIGHT TOWARDS SUNRISE TOMORROW
MORNING. THIS APPEARS TO BE A REASONABLE SOLUTION, AND HAVE
ADJUSTED POPS/QPF ACCORDINGLY THROUGH TOMORROW MORNING. DESPITE
THE INCREASING CHANCES OF RAIN/SNOW, ANY ACCUMULATION ACROSS THE
LOWER ELEVATIONS LOOKS TO BE MINIMAL, WITH SOME LIGHT TO MODERATE
ACCUMULATION ACROSS THE HIGHER ELEVATIONS OF THE FRONT RANGE.
SHORT TERM /THROUGH MONDAY/
ISSUED AT 241 PM MDT SUN APR 13 2025
SHOWERS CONTINUE TO GRADUALLY DEVELOP NEAR THE NORTHERN BORDER AT
THIS HOUR. THERE'S A SECONDARY FRONT WITH ABOUT A 10 DEGREE
TEMPERATURE DROP AND 10 MPH INCREASE IN THE NORTH WINDS THAT'S
WORKING SOUTH THROUGH WELD COUNTY. THIS WILL ENHANCE CONVERGENCE
ALONG THE FOOTHILLS AS THE QG FORCING ARRIVES AROUND DENVER ABOUT
5-6 PM, SO WE SHOULD SEE INCREASING SHOWER COVERAGE THEN. THE
MODELS HAVE BEEN FAIRLY CONSISTENT IN SHOWING TWO MAIN BATCHES OF
SHOWERS ASSOCIATED WITH DIFFERENT JET STREAKS, OR THE FRONT AND
BACK PARTS OF THE TROUGH IF YOU'D PREFER THAT WAY OF THINKING
ABOUT IT. THEY'VE ALSO BEEN REMARKABLY CONSISTENT IN FAVORING THE
LATITUDE OF ROUGHLY BOULDER COUNTY AND DIA FOR THE AREA WHERE THE
SHOWERS MOVE EAST FROM THE FOOTHILLS. THERE'S NOT A LOT OF
MOISTURE AND OUTSIDE OF THE AREA OF LIFT IT'S QUITE DRY. BUT THE
MID LEVEL LAPSE RATES ARE STEEP ENOUGH TO SUSTAIN THE CONVECTION
WITH THE LOW-LEVEL AND UPPER-LEVEL FORCING FOR LIFT. THE
TEMPERATURE FORECAST LOOKS PRETTY GOOD, THE SNOW LEVEL SHOULD STAY
ABOVE 6,000 FEET THIS EVENING, THEN DESCEND IN THE MIDDLE OF THE
NIGHT TO AROUND 5,000 FEET BY MORNING. BY THAT TIME, THE SHOWERS
SHOULD BE EXITING.
ALL OF THIS LOOKS PRETTY WELL COVERED IN THE GOING FORECAST. WE
DELAYED THE ONSET OF THE SHOWERS AN HOUR.
THERE SHOULD BE PRETTY SHARP CLEARING FROM NORTH TO SOUTH STARTING
AROUND SUNRISE AND THROUGH DENVER BY LATE MORNING.
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/
ISSUED AT 241 PM MDT SUN APR 13 2025
DRY CONDITIONS AND CHILLY TEMPERATURES ARE EXPECTED MONDAY NIGHT BEHIND
THE OUTGOING WEATHER SYSTEM, BRINGING US BACK TO NEAR NORMAL TEMPERATURE
VALUES FOR THIS TIME OF YEAR ACROSS THE FORECAST AREA. WNW FLOW ALOFT
WILL DECREASE AS THE UPPER LEVEL JET MOVES EASTWARD OVERNIGHT.
TUESDAY WILL SEE A RETURN OF WARMER TEMPERATURES AS A RIDGE BUILDS
OVER THE REGION AND FLOW ALOFT REVERTS BACK TO A WESTERLY REGIME.
700 MB TEMPERATURES WILL BE ROUGHLY 5 TO 10C WARMER THAN MONDAY'S,
WHICH WOULD SUPPORT AFTERNOON HIGH TEMPERATURES IN THE 70S ACROSS
THE LOWER ELEVATIONS, 50S TO LOW 60S FOR THE MOUNTAIN VALLEYS.
CLOUDS WILL INCREASE BEGINNING OVER THE CENTRAL PORTION OF THE
ROCKIES AND SPREAD NORTH AND EASTWARD AS A SHORTWAVE MOVING THROUGH
THE RIDGE BRINGS PACIFIC MOISTURE INTO THE REGION BY LATE
AFTERNOON/EARLY EVENING. THIS WILL BRING A CHANCE FOR SOME AFTERNOON
AND EVENING SHOWERS TO DEVELOP OVER THE MOUNTAINS, WITH A FEW ABLE
TO PUSH EAST OVER THE LOWER ELEVATIONS. CROSS-SECTIONS SHOW DRY MID
AND LOW LEVELS EAST OF THE MOUNTAINS, BUT SOME VIRGA SHOWERS WILL BE
POSSIBLE, MAINLY FOR AREAS SOUTH OF I-76 AND WEST OF I-25.
ENSEMBLES CONTINUE TO SLIGHTLY DIFFER IN SOLUTIONS, BUT DO SHOW
POTENTIAL FOR AN UPPER-LEVEL CLOSED LOW OFF THE COAST OF SOUTHERN
CALIFORNIA MOVE INLAND ON WEDNESDAY. WHILE THE CMCE KEEPS THE LOW
CLOSED OFF IN THE SUBTROPICAL FLOW AS IT ENTERS CALIFORNIA, THE EPS
AND GEFS TRANSITION TO AN OPEN TROUGH AND ALLOW FOR A MERGER WITH AN
UPPER TROUGH WITHIN THE POLAR JET OVER THE PACIFIC NORTHWEST. WITHIN
ALL OF THE SOLUTIONS IS A TRANSITION TO SOUTHWESTERLY FLOW ALOFT
OVER COLORADO BY MID WEEK, WITH INCREASING MOISTURE AND CHANCES FOR
MOUNTAIN SNOWFALL AND WIDESPREAD PRECIPITATION FOR THE FORECAST
AREA. ADDITIONALLY, ALL ENSEMBLES AGREE THAT A SURFACE LOW WILL FORM
SOMEWHERE ALONG THE LEE OF THE ROCKIES, BUT PLACEMENT VARIES PRETTY
SIGNIFICANTLY AT THIS POINT. WILL PROCEED WITH LITTLE ADJUSTMENTS
TO THE NBM AFTER WEDNESDAY AS IT SHOWS A DECENT REPRESENTATION OF
THE ACTIVE WEATHER PATTERN PICKING UP MIDWEEK AND INTO THE
WEEKEND, BUT EXPECT ADJUSTMENTS IN THE COMING DAYS AS GUIDANCE
GETS A BETTER GRASP ON THE SPECIFICS.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1130 PM MDT SUN APR 13 2025
NEXT BATCH OF SHOWERS ARE MOVING IN AND FORMING ACROSS THE DENVER
AREA. THESE SHOWERS WILL START OFF AS RAIN, BUT AS THE AIRMASS
COOLS WE'LL SEE A CHANGE TO SNOW AROUND 08Z. DUE TO WARM PAVEMENT
TEMPERATURES AND AIR TEMPERATURES STAYING NEAR THE FREEZING POINT,
ONLY A LIGHT ACCUMULATION ON GRASSY AND ELEVATED SURFACES. VERY
DRY AIR IS SITTING TO THE NORTH OVER WYOMING AND MOVES IN MONDAY
MORNING. THE SNOW ENDS 11-13Z, WITH LOWER CLOUDS (4000-6000 FEET)
LINGERING. SKIES THEN CLEAR FOR THE REST OF MONDAY AND MONDAY
NIGHT.
AS FAR AS WINDS GO, NORTH TO NORTHEAST WINDS WILL SLOWLY TURN
CLOCKWISE THOUGH THE NIGHT, BECOMING EASTERLY AROUND 12Z AND
SOUTHEASTERLY ~15Z. AFTER A PERIOD OF LIGHT SOUTHEAST WINDS, THE
WINDS SLOWLY TURN BACK TO THE NORTHEAST 20-21Z AT SPEEDS LESS THAN
15 KNOTS.
FIRE WEATHER
ISSUED AT 241 PM MDT SUN APR 13 2025
RED FLAG CONDITIONS CONTINUE ACROSS SOUTH PARK AND A FEW AREAS IN
FAR SOUTHERN JEFFERSON AND DOUGLAS COUNTIES. THESE WILL EASE BY
EARLY EVENING WITH UPSLOPE WINDS IN THE FOOTHILLS AND LIGHTER
WINDS AND COOLER TEMPERATURES IN SOUTH PARK.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...HIRIS
SHORT TERM...GIMMESTAD
LONG TERM...BONNER
AVIATION...MEIER
FIRE WEATHER...GIMMESTAD
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