388
FXUS65 KBOU 171138
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
538 AM MDT THU APR 17 2025
KEY MESSAGES
- TRANSITION DAY TODAY WITH GUSTY WINDS AND ARRIVAL OF A
SIGNIFICANT COLD FRONT.
- CRITICAL FIRE WEATHER CONDITIONS EXPECTED LATE THURSDAY MORNING
THROUGH THE AFTERNOON ALONG AND SOUTH OF I-70.
- COLDER WITH SNOW FOR MUCH OF THE FORECAST AREA FRIDAY AND FRIDAY
NIGHT. WINTER TRAVEL IMPACTS MAINLY FOR THE HIGH COUNTRY.
- STILL BELOW NORMAL TEMPERATURES ON SATURDAY, THEN WARMING TO
NEAR NORMAL SUNDAY AND ABOVE EARLY NEXT WEEK.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 348 AM MDT THU APR 17 2025
SOUTHWEST FLOW ALOFT WILL PREVAIL ACROSS COLORADO TODAY AND
TONIGHT AS AN UPPER LEVEL TROUGH DIGS STRAIGHT SOUTH ACROSS THE
NORTHERN ROCKIES AND INTO THE GREAT BASIN. THIS WILL BRING ONE
MORE MILD DAY TO THE AREA. AT THE SURFACE, BROAD LOW PRESSURE
DEEPENS ROUGHLY ALONG I-70. THERE IS A WEAK SURGE OF NORTHERLY
WINDS OVER SOUTHERN WYOMING THAT WILL PUSH SOUTH INTO NORTHEAST
COLORADO THIS MORNING. IT ENDS UP STALLING NEAR I-70, AND THEN
MOST MODELS SHOW IT RETREATING BACK NORTH LATER THIS MORNING.
USUALLY THIS ISN'T THE CASE AND THE COLDER AIR REMAINS STATIONARY
OR RETREATS JUST A LITTLE. BELIEVE THIS IS THE CASE TODAY,
ESPECIALLY WITH THE SURFACE TROUGH BEING ALONG OR JUST SOUTH OF
I-70. ALSO OF NOTE, THE ECMWF AIFS (ARTIFICIAL
INTELLIGENCE/INTEGRATED FORECAST SYSTEM) SHOWS THE FRONT STALLING
AND NOT RETREATING AS WELL. BECAUSE OF THIS, DECIDED TO CANCEL THE
FIRE WEATHER WATCH FOR THE DENVER METRO AREA. SEE FIRE WEATHER
SECTION BELOW FOR MORE DETAILS.
THE MAIN COLD FRONT BLASTS INTO NORTHERN COLORADO MID AFTERNOON
AND THEN RACES SOUTHWARD PUSHING ACROSS THE PALMER DIVIDE AND INTO
SOUTHERN COLORADO EARLY TO MID EVENING. GUSTS WITH THE FRONT WILL
BE AROUND 45 MPH. WINDS THEN DECREASE AFTER AN HOUR OR TWO TO 15
TO 25 MPH.
AS FAR AS PRECIPITATION GOES, SCATTERED SHOWERS WILL LINGER OVER
THE MOUNTAINS THIS MORNING BEFORE A DRY SLOT MOVES OVER THIS
AFTERNOON. THE MOUNTAINS COULD SEE A COULD A COUPLE INCHES OF SNOW
THIS MORNING BEFORE THERE'S A BREAK. THE AIR MOISTENS BEHIND THE
COLD FRONT LATER TODAY WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING BEHIND IT. QG ASCENT AND LIFT FROM THE
JET BRING WIDESPREAD SNOW TO THE MOUNTAINS TONIGHT. IT TAKES SOME
TIME FOR THE BEST LIFT AND MOISTURE ALOFT TO SHIFT EAST OVER THE
PLAINS. MEANWHILE WHILE THE LOWER AIRMASS BECOMES SATURATED. THIS
COULD LEAD TO A BRIEF PERIOD OF DRIZZLE/FREEZING DRIZZLE AFTER
MIDNIGHT. DEEP MOISTURE SPREADS EASTWARD PRIOR TO SUNRISE. OUTSIDE
OF ANY DRIZZLE, IT WILL BECOMES COLD ENOUGH FOR ALL SNOW ACROSS
THE LOWER ELEVATIONS BY MIDNIGHT.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
ISSUED AT 412 AM MDT THU APR 17 2025
AN UPPER LOW OVER NORTHERN UTAH FRIDAY MORNING, WILL MOVE
SOUTHWARD DOWN INTO THE FOUR CORNERS BY 12Z SATURDAY MORNING. IT
THEN MOVES INTO CENTRAL NEW MEXICO BY 00Z SATURDAY LATE AFTERNOON
AND INTO THE TEXAS PANHANDLE BY 12Z SUNDAY MORNING. UPPER
TROUGHING IS OVER THE CWA SATURDAY AND SATURDAY NIGHT WITH. THE
UPPER LEVEL FLOW WILL BE SOUTHWESTERLY FRIDAY INTO SATURDAY
MORNING, THEN EVENTUALLY WEAK NORTHWESTERLY BY 12Z SUNDAY MORNING.
THERE IS WEAK UPWARD VERTICAL VELOCITY NOTED ON THE QG OMEGA
FIELDS FRIDAY WELL INTO SATURDAY FOR ALL THE CWA, WITH THE
STRONGEST SYNOPTIC SCALE ENERGY TO THE SOUTH OF COLORADO. THE LOW
LEVEL PRESSURE AND WIND FIELDS KEEP UPSLOPE FLOW GOING FRIDAY AND
FRIDAY NIGHT, WITH CROSS SECTIONS SHOWING THE UPSLOPE TO GET UP
AND OVER THE DIVIDE FRIDAY AFTERNOON AND FRIDAY NIGHT. SURFACE
HIGH PRESSURE WILL BE IN PLACE SATURDAY AND SATURDAY NIGHT WITH A
WEAK GRADIENT AND MAINLY WEAK NORMAL DIURNAL WIND PATTERNS BOTH
PERIODS.
CROSS SECTIONS SHOW MOISTURE TO BE DEEP FRIDAY WELL INTO SATURDAY
BEFORE DECREASING LATER SATURDAY AFTERNOON AND EVENING. SATURDAY
OVERNIGHT LOOKS PRETTY DRY. QPF FIELDS SHOW WIDESPREAD LIGHT
PRECIPITATION, MAINLY SNOW FOR THE CWA FRIDAY AND MUCH OF FRIDAY
NIGHT. THERE COULD BE SOME RAIN MIXED IN OVER THE EASTERN PLAINS ON
FRIDAY. AFTER 06Z FRIDAY NIGHT, MEASURABLE PRECIPITATION DECREASES
AND MOVES SOUTH OUT OF THE CWA. THERE IS LIMITED MEASURABLE
PRECIPITATION SATURDAY AFTERNOON AND EARLY EVENING, MAINLY OVER
THE SOUTHWESTERN QUARTER OF THE CWA.
MODELS CONTINUE TO REFRAIN FROM SIGNIFICANT PRECIPITATION FOR THE
CWA, SO WINTER WEATHER ADVISORIES WILL SUFFICE FOR THE MOUNTAINS,
FOOTHILLS AND PARK COUNTY FRIDAY AND FRIDAY NIGHT. FOR TEMPERATURES,
FRIDAY'S HIGHS WILL BE 12-17 C COLDER THAN TODAY'S READINGS
BEFORE THE COLD FRONT MOVES IN WITH WIDESPREAD 30S F FOR ALL OF THE
PLAINS. FRIDAY NIGHT'S LOWS WILL BE COLD WITH UPPER TEEN TO MID
20S FOR THE PLAINS. READINGS WARM A LITTLE ON SATURDAY BUT ARE
STILL BELOW SEASONAL NORMALS.
FOR THE LATER DAYS, SUNDAY THROUGH WEDNESDAY, MODELS SHOW
NORTHWESTERLY FLOW ALOFT SUNDAY BECOMING ZONAL BY MONDAY AND
CONTINUING THROUGH MID WEEK. THERE IS WEAK UPPER TROUGHING LATE
MONDAY NIGHT INTO TUESDAY. THE SYNOPTIC SCALE ENERGY ISN'T MUCH
THROUGH THE FOUR DAY PERIOD. THERE WILL BE ENOUGH MOISTURE FOR 30-
60% CHANCES OF MAINLY LATE DAY ALPINE SHOWERS MONDAY, TUESDAY AND
WEDNESDAY. THE PLAINS COULD SEE 10-30% POPS LATE DAY MONDAY, AND
20-50% POPS LATE DAY TUESDAY AND WEDNESDAY. IT WILL BE A BIT
UNSETTLED BUT SIGNIFICANT PRECIPITATION IS NOT EXPECTED.
TEMPERATURES WILL CONTINUE TO WARM ON SUNDAY WITH HIGHS OVER THE
PLAINS GETTING TO NEAR 60 DEGREES. HIGHS FOR MONDAY THROUGH
WEDNESDAY WILL BE IN THE UPPER 60S TO LOWER 70S FOR MOST OF THE
PLAINS.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 538 AM MDT THU APR 17 2025
SOUTHWEST WINDS TO PREVAIL UNTIL 15-16Z, THEN A WEAK PUSH/COLD
FRONT BRINGS NORTH TO NORTHEAST WINDS. THE WIND FORECAST BECOMES
VERY UNCERTAIN AROUND AND AFTER 18Z. SOME MODELS SHOW THIS FRONT
STALLING OUT WITH VARIABLE WINDS INTO THURSDAY AFTERNOON. OTHER
MODELS SHOW THE NORTH TO NORTHEAST WINDS RETREAT DUE TO GUSTY
WEST TO SOUTHWEST WINDS. USUALLY THESE FRONTS ARE SLOW OR DON'T
RETREAT, SO WENT WITH THE LIGHTER VARIABLE WINDS AT 18Z AND THEN
ADDED A TEMPO FOR THE GUSTY WEST-SOUTHWEST WINDS. THE MAIN COLD
FRONT PLOWS SOUTH THROUGH THE DENVER AREA BRINGING NORTHEAST
WINDS TO 40 KNOTS LATE THIS AFTERNOON 22-23Z. NORTHEAST WINDS
CONTINUE THROUGH TONIGHT AND SLOWLY DECREASING AFTER 00Z FRIDAY.
VFR WILL PREVAIL THROUGH THIS AFTERNOON 00Z FRIDAY, THEN CLOUDS
START TO LOWER. SHOWERS AND POSSIBLY A THUNDERSTORMS (10% CHANCE)
WILL BE POSSIBLE BEHIND THE COLD FRONT, MAINLY AFTER 00Z FRIDAY.
IT BECOMES COLD ENOUGH FOR ALL SNOW AFTER 06Z FRIDAY. HOWEVER,
CROSS SECTIONS ONLY SHOW THE AIRMASS SATURATED UP TO 700MB UNTIL
09-12Z FRIDAY. IF THIS HAPPENS, WE COULD SEE A BRIEF PERIOD OF
FREEZING DRIZZLE. AIR TEMPERATURES WILL BE IN THE UPPER 20S DURING
THIS TIME. THIS WOULD LIMIT IMPACTS TO ELEVATED SURFACES. SNOW IS
EXPECTED TO INCREASE FRIDAY MORNING, BUT LIGHT TO BRIEFLY
MODERATE INTENSITY IS EXPECTED MAKE IT DIFFICULT FOR SNOW TO
ACCUMULATE ON PAVED SURFACES UNTIL FRIDAY EVENING.
FIRE WEATHER
ISSUED AT 348 AM MDT THU APR 17 2025
IT WILL BE WARM, DRY, AND WINDY AHEAD OF A COLD FRONT TODAY ALONG
AND SOUTH OF I-70 WHERE THERE IS A RED FLAG WARNING IN EFFECT.
WINDS TO 45 MPH AND RELATIVE HUMIDITIES DOWN 10 PERCENT ARE
EXPECTED THIS AFTERNOON. TRICKY FORECAST REGARDING THE FIRE
WEATHER WATCH FOR DENVER AND NEARBY PLAINS WITH SOME MODELS
SHOWING STRONG WEST WINDS AND SOME NOT. TYPICALLY, THE MODELS
OVERDUE THE AMOUNT WESTERLY MIXING IN THESE CASES AND THUS DECIDED
TO CANCEL THE FIRE WEATHER WATCH. A STRONG COLD FRONT DROPS SOUTH
INTO NORTHEAST COLORADO MID AFTERNOON AND PUSHES SOUTH ACROSS
I-70 AND THE PALMER DIVIDE BY EARLY EVENING. THIS WILL BRING A
WIND SHIFT TO THE NORTHEAST WITH GUSTS TO 45 MPH. TEMPERATURES
DROP RAPIDLY (20F OR SO) AND RELATIVE HUMIDITIES INCREASE.
BOU WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM MDT
SATURDAY FOR COZ031-033-034.
WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 6 AM MDT SATURDAY
FOR COZ035-036.
RED FLAG WARNING FROM 10 AM THIS MORNING TO 7 PM MDT THIS
EVENING FOR COZ214-216-241-246-247.
WINTER WEATHER ADVISORY FROM 9 AM FRIDAY TO 6 AM MDT SATURDAY
FOR COZ037.
SHORT TERM.....MEIER
LONG TERM......RJK
AVIATION...MEIER
FIRE WEATHER...MEIER
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