383
FXUS65 KBOU 180617
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1217 AM MDT FRI SEP 18 2026
KEY MESSAGES
- INCREASING COVERAGE AND INTENSITY OF AFTERNOON/EVENING SHOWERS
AND T-STORMS FOR THE LOWER ELEVATIONS, PEAKING SATURDAY WHEN
LOCALLY HEAVY RAINFALL CAN BE EXPECTED ACROSS THE PLAINS.
- WARM TEMPERATURES THROUGH SATURDAY TO GIVE WAY TO MORE SEASONAL
CONDITIONS SUNDAY ONWARDS.
- TRENDING DRIER SUNDAY INTO MONDAY, ALTHOUGH AT LEAST ISOLATED TO
SCATTERED SHOWERS WILL REMAIN EACH DAY.
DISCUSSION /THROUGH THURSDAY/
ISSUED AT 1144 PM MDT THU SEP 17 2026
THOUGH NOT AS CLIMATOLOGICALLY ANOMALOUS AS THE LAST COUPLE OF
DAYS, PRECIPITABLE WATER VALUES WILL REMAIN PLENTY ELEVATED TODAY,
COMBINING WITH A HAIR HIGHER INSTABILITY TO PROMOTE RENEWED
SCATTERED SHOWERS AND A FEW GENERALLY WEAK THUNDERSTORMS THIS
AFTERNOON THROUGH THE EVENING. AS WAS THE CASE OVER THE PAST FEW
DAYS, STEERING LEVEL FLOW SHOULD REMAIN ABOVE 20-25 KTS, THUS
KEEPING STORMS ON THE MOVE AND LIMITING OVERALL ACCUMULATIONS FOR
MOST AREAS (WITH SOME LOCATIONS, PER USUAL, REMAINING DRY).
TEMPERATURES WILL CONTINUE TO HOLD 5-10 DEGREES ABOVE NORMAL FOR
THE DATE.
SATURDAY REMAINS THE DAY TO WATCH IN TERMS OF BOTH SEVERE THREATS
AND LOCALIZED FLOODING POTENTIAL. DESPITE A SMALL DOWNTICK IN
AVAILABLE MOISTURE, PWS WILL REMAIN ELEVATED, WITH MODERATELY
DEEP WARM CLOUD DEPTHS AND INCREASED INSTABILITY AS COOL AIR
ADVECTION RETURNS ALOFT WITH THE APPROACHING UPPER-LEVEL LOW.
STEERING LEVEL FLOW WILL CONTINUE TO BE HEFTY, BUT IMPROVED SHEAR
AND HIGHER COVERAGE OF LATE DAY CONVECTION WILL LEAD TO A GREATER
POTENTIAL FOR HEAVY DOWNPOURS NAMELY OVER THE PLAINS. THE
EXCEPTION TO THE ABOVE TREND WILL BE THE HIGH COUNTRY, WHERE DRIER
AIR WILL STEADILY GAIN INFLUENCE THROUGH THE WEEKEND AND REDUCE
PRECIPITATION COVERAGE AND INTENSITY. SCATTERED AFTERNOON SHOWERS
AND THUNDERSTORMS LOOK TO CONTINUE INTO SUNDAY WITH THE PASSAGE OF
THE UPPER-LEVEL TROUGH AND SUFFICIENT SHEAR AND INSTABILITY,
HOWEVER A MORE NOTEWORTHY DECLINE IN PWS AND COOLER SURFACE
CONDITIONS WOULD SUGGEST A SLIGHT REDUCTION IN ACTIVITY COMPARED
TO SATURDAY.
TRANSIENT RIDGING EMERGES BY MONDAY, PROVIDING FOR A DRIER DAY
ACROSS MOST OF THE REGION WITH AFTERNOON SHOWERS BECOMING MUCH
MORE ISOLATED IN NATURE, ALBEIT NOT DISAPPEARING ENTIRELY.
TEMPERATURES WILL BE FAIRLY SEASONAL IF NOT A TOUCH BELOW AVERAGE,
WITH HIGHS IN THE MID 70'S MONDAY FOR THE LOWER ELEVATIONS.
SOUTHWEST FLOW ALOFT WILL DOMINATE PAST MONDAY, ALLOWING FOR THE
INTRUSION OF A FEW SHORTWAVES THROUGH THE WEEK AND KEEPING
OPPORTUNITIES FOR ADDITIONAL PRECIPITATION IN PLACE MOST DAYS,
WITH THE MOUNTAINS BEING BEST POSITIONED FOR THE BETTER COVERAGE GIVEN
THE FLOW PATTERN. BEYOND THAT, THERE'S STILL AMPLE VARIANCE IN
MODEL GUIDANCE, LIMITING HOW MUCH DETAIL WE CAN EXTRACT.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1217 AM MDT FRI SEP 18 2026
VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR ALL TERMINALS THROUGH
THE TAF PERIOD. THE CURRENT LIGHT/VRB WINDS WILL STEADILY MORPH
INTO A BETTER DEFINED (ALBEIT STILL WEAK...< 7 KT) DRAINAGE FLOW
PATTERN OVER THE NEXT COUPLE OF HOURS, WITH THE LATTER HOLDING
THROUGH MID-MORNING BEFORE WINDS RETURN TO A MORE VARIABLE REGIME.
SPEEDS WILL REMAIN LIGHT AND UNDER 10 KTS THROUGH EARLY/MID-
AFTERNOON.
SCATTERED SHRA/TSRA WILL REDEVELOP MID-AFTERNOON AND CARRY
POTENTIAL FOR GUSTY OUTFLOWS, MAINLY AFTER 22-23Z. COVERAGE
SHOULD DWINDLE MID-EVENING, BUT ISOLATED SHRA MAY LINGER THROUGH
MOST OF THE EVENING.
WINDS WILL FAVOR A RETURN TO DRAINAGE FLOW IN THE EVENING.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...BRQ
AVIATION...BRQ
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