620
FXUS65 KBOU 211113
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
513 AM MDT WED OCT 21 2026
KEY MESSAGES
- WARM AND DRY CONDITIONS CONTINUE ACROSS THE LOWER ELEVATIONS FOR
THE NEXT FEW DAYS, WITH SCATTERED LIGHT RAIN AND SNOW SHOWERS
ACROSS THE HIGHER ELEVATIONS.
- COOLER, UNSETTLED WEATHER POTENTIALLY RETURNS THIS WEEKEND
ACROSS THE FORECAST AREA, INCLUDING THE FRONT RANGE/I-25
CORRIDOR.
- AT LEAST A BRIEF WARM-UP LIKELY SOMETIME EARLY OR MID-WEEK NEXT
WEEK.
DISCUSSION /THROUGH TUESDAY/
ISSUED AT 1142 PM MDT TUE OCT 20 2026
THE NEXT COUPLE OF DAYS WILL BE DOMINATED BY BROAD SOUTH-
SOUTHWESTERLY FLOW ALOFT, AS A STRONG TROUGH TO THE WEST SLOWLY
DRIFTS OFF TO THE NORTHEAST, WHILE A RIDGE SLOWLY BUILDS JUST TO
THE EAST OF OUR FORECAST AREA. EMBEDDED IN THE FLOW IS SOME
EXTREMELY IMPRESSIVE MOISTURE. FORECAST PW AND 500/700MB SPECIFIC
HUMIDITY INCREASES SIGNIFICANTLY OVER THE NEXT 24 HOURS OR SO,
WITH MOST OF THESE VALUES REACHING STANDARDIZED ANOMALIES OF 4-6
SIGMA... WELL OUTSIDE CLIMATOLOGY FOR THIS TIME OF YEAR. OF
COURSE, THE FLOW ALOFT IS RATHER UNFAVORABLE FOR SIGNIFICANT
OROGRAPHIC PRECIPITATION HERE. WE SHOULD STILL MANAGE SCATTERED
RAIN AND SNOW SHOWERS BOTH WEDNESDAY AND THURSDAY, BUT THE MORE
IMPRESSIVE RAINFALL TOTALS WILL BE CONFINED TO SOUTHWEST COLORADO.
THE PATTERN WILL ALSO FAVOR ABOVE NORMAL TEMPERATURES ACROSS THE
REGION, WITH SNOW LEVELS SITTING AROUND 12-14KFT, AND HIGHS IN THE
70S ACROSS MOST OF THE PLAINS.
THE MID-LEVEL FLOW STRENGTHENS A BIT ON FRIDAY AS A SHORTWAVE
ROTATES AROUND THE PARENT TROUGH AXIS FROM SOUTHEASTERN UTAH INTO
WESTERN WYOMING. 700-500MB FLOW APPROACHES 30-40KT FRIDAY
AFTERNOON WITH A GENERALLY DRY/SUBSIDENT AIRMASS... WHICH SHOULD
ALLOW FOR A FEW GUSTS OF 30-40 MPH ACROSS THE EASTERN PLAINS. A
FAIRLY STRONG LEE CYCLONE OVER NORTHERN COLORADO WOULD LIKELY
LIMIT WIND GUSTS ALONG AND NORTH OF I-76, MEANING THAT THE
NORTHWEST DENVER METRO COULD SEE A FAIRLY CALM DAY WHILE THE
SOUTHEAST METRO ENDS UP RATHER BREEZY. THESE DETAILS ARE HARD TO
PINPOINT BUT SHOULD BECOME MORE CLEAR OVER THE NEXT COUPLE DAYS
WHERE CAMS WILL BE AVAILABLE. ACROSS THE MOUNTAINS, THERE COULD BE
A FEW SHOWERS DURING THE DAY BUT MOST OF THE MOISTURE EXITS THE
AREA PRETTY QUICKLY.
WHILE THE MAIN TROUGH EJECTS OUT OF THE REGION ON FRIDAY,
GUIDANCE IS INSISTENT THAT AT LEAST ONE PIECE OF THIS TROUGH WILL
BE LEFT OVER THE DESERT SOUTHWEST. THERE'S STILL CONSIDERABLE
SPREAD ACROSS BOTH THE PHYSICS AND AI-BASED FORECAST GUIDANCE IN
THIS PERIOD, THOUGH IT APPEARS WE ARE STARTING TO SEE A GRADUAL
CONVERGENCE TOWARDS A SINGLE SOLUTION, WHERE THE LEFTOVER PIECE OF
THE TROUGH DRIFTS NORTHWARD AND CLOSES OFF SOMETIME ON SATURDAY.
THAT CLOSED LOW THEN LIFTS NORTHEASTWARD AND EVENTUALLY INTERACTS
WITH A RELATIVELY CONFLUENT NORTHERN JETSTREAM... LEADING TO THE
UPPER LOW SHEARING OUT SUNDAY INTO MONDAY. THE 700MB LOW, THOUGH
WEAKER THROUGHOUT THE PERIOD, FOLLOWS A SIMILAR TRACK, WITH THE
FLOW BRIEFLY ALIGNED TO ADVECT SOME DEEPER MOISTURE INTO EASTERN
COLORADO SATURDAY NIGHT THROUGH SUNDAY.
WE'LL SEE QUITE THE CHANGE FROM FRIDAY TO SATURDAY ACROSS MOST OF
THE LOWER ELEVATIONS, AS A COLD FRONT PUSHES INTO THE REGION.
WHILE TEMPERATURES ON FRIDAY MAY HIT 80F, MOST OF THE LOWER
ELEVATIONS WILL STRUGGLE TO REACH 60F ON SATURDAY. SIMILAR OR EVEN
COOLER TEMPERATURES ARE EXPECTED BY SUNDAY WITH COOLING MID-LEVEL
TEMPERATURES AND INCREASED CLOUD COVER. THE GFS REMAINS ON THE
WARMER SIDE OF GUIDANCE THIS EVENING, WITH THE ECMWF AND THE AI
GEFS/ECMWF ENSEMBLE ARE ~10-15F COOLER. EITHER WAY, HIGHS WILL
RETURN TO NEAR OR SLIGHTLY BELOW NORMAL VALUES, ALONG WITH
INCREASING CLOUD COVER AND PRECIPITATION CHANCES BY SATURDAY
NIGHT. GIVEN THE LARGE SPREAD ACROSS CURRENT GUIDANCE IT'S
DIFFICULT TO SAY TOO MUCH MORE THAN THAT. CURRENT TRENDS CONTINUE
TO PUSH MORE SIGNIFICANT MOISTURE INTO THE REGION FOR SUNDAY,
THOUGH OUR NEW POP FORECAST ISN'T TOO MUCH HIGHER THAN PREVIOUS
FORECAST CYCLES. THERE IS AT LEAST SOME REASON FOR OPTIMISM IF
YOU'RE HOPING FOR MEANINGFUL PRECIPITATION.
BEYOND THIS WEEKEND, MOST GUIDANCE DOES (AT LEAST BRIEFLY)
SUGGEST THAT TEMPERATURES WILL WARM BACK INTO THE 60S ACROSS THE
PLAINS, WITH GENERALLY DRY CONDITIONS. HOWEVER, IT'S DIFFICULT TO
READ TOO MUCH INTO THIS GIVEN THE UNCERTAINTY WITH THE THE
NORTHERN JETSTREAM BEYOND ROUGHLY DAYS 4-5. THE MULTI-MODEL MEAN
WOULD BE WARM AND DRY THROUGH THE END OF THE FORECAST PERIOD, WITH
A MORE ACTIVE FORECAST PATTERN CLOSER TO THE END OF THE MONTH.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 510 AM MDT WED OCT 21 2026
WINDS WERE LIGHT SSW EARLY THIS MORNING AND WILL BECOME LIGHT AND
VARIABLE BY 15Z. BY 19Z, WINDS WILL BECOME SE AND THEN SLOWLY
INCREASE THRU THE AFTN. FOR THIS EVENING, EXPECT WINDS TO BECOME
MORE SOUTHERLY BY 03Z AND THEN TURN MORE SSW BY 07Z.
VFR CONDITIONS WILL BE IN PLACE THRU THE PERIOD ALTHOUGH THERE
WILL BE A GRADUALY INCREASE IN MID CLOUDS ABOVE 12000 FT BY LATE
AFTERNOON.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HIRIS
AVIATION...RPK
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