Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 212219
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
319 PM MST FRI NOV 21 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 318 PM MST FRI NOV 21 2014

THE CLOUDINESS IS QUITE MINIMAL OVER THE FORECAST AREA AT THIS
TIME. WINDS AR PRETTY LIGHT AS WELL. THERE ARE FEW GUSTS TO 20
KNOTS ALONG THE DIVIDE ONLY. MODELS HAVE A WEAK UPPER TROUGH AXIS
TO MOVE ACROSS THE CWA LATE THIS EVENING THROUGH PRE DAWN SATURDAY
MORNING. THE WINDS ALOFT ARE PROGGED TO BE WEAK AND WESTERLY THIS
EVENING...THEN NORTHWESTERLY AND WEAK AFTER THE AXIS MOVES ACROSS.
WINDS ALOFT ARE BACK TO NEAR WESTERLY BY 00Z LATE SATURDAY
AFTERNOON BUT SPEEDS ARE ON THE INCREASE. THE SYNOPTIC SCALE
ENERGY IS WEAK AND DOWNWARD IN NATURE OVERNIGHT AND SATURDAY
MORNING. THERE IS WEAK UPWARD QG VERTICAL VELOCITY PROGGED FOR
SATURDAY AFTERNOON IN ADVANCE OF THE NEXT UPPER TROUGH. THE
BOUNDARY LAYER FLOW WILL BE DOMINATED BY SOUTHWESTERLY DOWNSLOPING
WITH A LOW LEVEL TROUGH OVER EASTERN COLORADO. THE MODELS AND
SATELLITE PICTURES POINT TO LITTLE CLOUDINESS OVERNIGHT INTO
SATURDAY MORNING. UPPER LEVEL CLOUDINESS MOVES IN SATURDAY
MORNING..AND THE WESTERN CWA HAS PRETTY DEEP MOISTURE IN PLACE BY
00Z SATURDAY AFTERNOON LATE. THE QPF FIELDS HAVE ZERO
PRECIPITATION FOR THE CWA TONIGHT THROUGH 18Z SATURDAY MORNING.
ALL MODELS HAVE SOME MEASURABLE SNOW FOR THE MOUNTAINS SATURDAY
AFTERNOON. THE INCOMING TROUGH BRINGS IN UPWARD MOTION...GOOD
MOISTURE...AND INCREASED MOUNTAIN TOP WINDS FOR OROGRAPHICS. WILL
GO WITH SIGNIFICANTLY INCREASING POPS SATURDAY AFTERNOON IN THE
MOUNTAINS. NO POPS ELSEWHERE. FOR TEMPERATURES...SATURDAY`S HIGHS
ARE 1.0-3.5 C WARMER THAN TODAY`S HIGHS.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 318 PM
MST FRI NOV 21 2014

A SERIES OF SMALL TROUGHS WILL MOVE OVER COLORADO IN THE STRONG
NORTHWEST FLOW ALOFT BEGINNING SATURDAY NIGHT. AT THIS POINT THE
BEST LIFT APPEARS TO BE SATURDAY EVENING AT THE NOSE OF THE
JET...BUT THERE IS DEEP MOISTURE AND STRONG WINDS INTO SUNDAY.
ANOTHER WAVE MONDAY COULD BRING AN UPSWING IN SNOW AGAIN...THOUGH
IT LOOKS LIKE THE WINDS WILL NOT BE AS STRONG. WINTER STORM WATCH
LOOKS GOOD FOR THIS PERIOD AS THE SUSTAINED OROGRAPHIC SNOW WITH A
FEW PERIODS OF DYNAMIC ENHANCEMENT SHOULD PRODUCE HEAVY SNOWFALL.
PLENTY OF WIND TO EXACERBATE THE SITUATION AS WELL. I DID BUMP UP
THE SNOWFALL AMOUNTS FOR THE FIRST PART OF THE PERIOD WITH
INCREASING CONFIDENCE. WE COULD NEED MORE FOR MONDAY AS WELL. FOR
THE PLAINS THERE COULD BE A FEW SHOWERS DURING THE PERIODS OF QG
FORCING...MAINLY SATURDAY NIGHT...BUT DOWNSLOPE DRYING WILL
SEVERELY LIMIT THE CHANCE OF RAIN OR SNOW. THERE MAY BE A HIGH
WIND THREAT IN THE FOOTHILLS...BUT JUST A BRUTE FORCE EVENT FROM
MIXING OF THE STRONG WINDS ALOFT. PLAINS ALSO NEEDED A BIT MORE
WIND...PROBABLY NOT MUCH OF A HIGH WIND THREAT BUT COULD SEE GUSTS
TO 50 MPH ON SUNDAY AND MONDAY AFTERNOONS.

BY TUESDAY THE FLOW WILL BE DIMINISHING AND THERE SHOULD BE LESS
MOISTURE...BUT MODELS DO HAVE ANOTHER SHORTWAVE TO KEEP CLOUDS AND
SOME MOUNTAIN SNOW. THERE WILL BE A WINDOW OF WARMER AND DRIER
CONDITIONS ABOUT WEDNESDAY...WHICH COULD LAST INTO THURSDAY AND
WARMING ALONG THE FRONT RANGE COULD BE CONSIDERABLE AS THERE WILL
STILL BE ENOUGH WIND FOR SOME DOWNSLOPING AND A LEE TROUGH.
DESPITE BETTER AGREEMENT ON A BROAD RIDGE UPSTREAM FOR
THURSDAY...THERE ARE DIFFERING DETAILS ON POSSIBLE SHORTWAVE
ENERGY AND ANOTHER COLD FRONT COMING DOWN THE PLAINS. MOST MODEL
SOLUTIONS HAVE THURSDAY WARM AND DRY WITH JUST A MINOR NORTHERLY
SURGE WEDNESDAY AFTERNOON OR EVENING...BUT THERE IS STILL SOME
UNCERTAINTY THERE. BETTER AGREEMENT ON ANOTHER TROUGH AND FRONT
LATER...EITHER FRIDAY OR SATURDAY...THAT MAY BRING MORE
SIGNIFICANT SNOW AND COOLING. LEFT SOME LOW POPS IN TO ACCOUNT FOR
THE REMAINING UNCERTAINTY. MODELS THAT FLIP CAN FLOP...NOT TOO
TRUSTING OF RESOLVING SHORTWAVES IN STRONG NW FLOW. HOWEVER...IT
LOOKS LIKE CHANCE OF ANY SUBSTANTIAL WINTER WEATHER IN THE WED-
FRI PERIOD ARE SLIM AT BEST.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z SATURDAY LATE AFTERNOON)
ISSUED AT 318 PM MST FRI NOV 21 2014

A WEAK PRESSURE GRADIENT WILL KEEP WINDS WEAK AT DIA. NORMAL
DRAINAGE PATTERNS SHOULD KICK IN THIS EVENING...BY 03Z...BUT
SPEEDS SHOULD BE UNDER 12 KNOTS. SOUTHWESTERLIES SHOULD PREVAIL
ALL DAY SATURDAY...BUT NO SIGNIFICANT SPEEDS. THERE SHOULD BE NO
CEILING ISSUES THE NEXT 24 HOURS.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY
AFTERNOON FOR COZ031-033-034.

&&

$$

SHORT TERM...RJK
LONG TERM...GIMMESTAD
AVIATION...RJK



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