Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 300217
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
817 PM MDT FRI APR 29 2016

.UPDATE...
ISSUED AT 817 PM MDT FRI APR 29 2016

THE UPPER LEVEL LOW WILL BE MOVING OUT OF THE STATE TONIGHT AND
THE WEAK UPWARD FORCING OVER THE NORTHWEST QUADRANT OF THE LOW
WILL BE DIMINISHING. LIGHT SNOW CONTINUES OVER THE NORTHEAST
PLAINS...BUT ACCUMULATIONS HAVE BEEN LIGHT UP TO THIS POINT. AREAS
ALONG THE FRONT RANGE HAVE BEEN FREE OF PRECIPITATION OVER THE
PAST FEW HOURS...AND SNOW IN THE MOUNTAINS HAS BECOME
SPOTTY...BASED ON A REVIEW OF VARIOUS WEB CAMERAS. THE HRRR AND
RAP MODELS SHOW THAT SNOW WILL CONTINUE DECREASING THROUGH
TONIGHT...SO IT LOOKS LIKE THE ACCUMULATING PART OF THE STORM IS
OVER. WILL BE CANCELLING THE ADVISORIES IN THE MOUNTAINS AND THE
PALMER DIVIDE AS LITTLE MORE THAN 1 INCH OF ACCUMULATION IS
EXPECTED OVERNIGHT. WITH THE MOIST AIRMASS IN PLACE OVER THE
PLAINS AND LIGHT NORTHERLY FLOW EXPECTED TO CONTINUE
OVERNIGHT...HAVE BUMPED UP THE COVERAGE OF FOG WHICH IS EXPECTED
TO DEVELOP ACROSS NORTHEAST COLORADO. THE FORECAST AREA WILL BE
UNDER WEAK NORTHERLY RETURN FLOW THROUGH TOMORROW...AND DIURNAL
HEATING SHOULD LEAD TO RE-DEVELOPMENT OF RAIN/SNOW SHOWERS
TOMORROW. WILL NOT MAKE ANY CHANGES TO THE THAT FORECAST PERIOD
FOR NOW.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 415 PM MDT FRI APR 29 2016

NEGATIVE TILT UPPER TROUGH ANCHORED TO A CLOSED LOW PRESENTLY OVER
THE SAN JUAN MTNS IN SWRN COLORADO IS PROGGED TO SWING NORTHEASTWARD
OVER NORTHERN AND EASTERN COLORADO OVERNIGHT. A LIGHT TO MODERATE
SOUTHEASTERLY FLOW AHEAD OF THIS TROUGH CONTINUES TO PROVIDE AMPLE
MOISTURE AND LIFT NECESSARY TO GENERATE WIDESPREAD PRECIPITATION
OVER NORTHEAST COLORADO TODAY. PRECIPITATION HAS PRIMARILY BEEN SNOW
SINCE LATE THIS MORNING...ALTHOUGH THERE ARE STILL POCKETS OF
RAINFALL ACROSS FAR NORTHEAST COLORADO...SUCH AS THE MODERATE
RAINFALL AT STERLING. HOWEVER WITH TEMPERATURES JUST ABOVE FREEZING
AND ENOUGH SOLAR ENERGY FILTERING THROUGH THE OVERCAST...THERE HAS
NOT BEEN SNOW ACCUMULATION ON THE PLAINS...EXCEPT ALONG THE PALMER
DIVIDE IN DOUGLAS AND ELBERT COUNTIES. RECEIVED A SNOW DEPTH REPORT
OF 14 INCHES NEAR THE TOWN OF MATHESON SOUTHEAST CORNER OF ZONE 41.
THIS LOOKS VERY LOCALIZED. SNOW AMOUNTS ACROSS THIS ZONE GENERALLY
IN THE 3-8 INCH RANGE. AS FOR THE FRONT RANGE MTNS...FOOTHILLS AND
SOUTH PARK ZONES UNDER THE WINTER STORM WARNING...SNOW ACCUMS WITH
THIS STORM MARGINALLY REACHED WARNING CRITERIA. HIGH COUNTRY ROAD
WAYS ALSO SAW LITTLE IF ANY SNOW ACCUMULATION.

RADAR SHOWS A SHARP SOUTHERN EDGE TO THE PRECIP BAND LIFTING NORTH
OVER NERN COLORADO ATTM. THIS EDGE HAS REACHED SRN LINCOLN COUNTY.
AND IS EXPECTED TO THE INTERSTATE 70 CORRIDOR AROUND DENVER BY 02Z
THIS EVENING...AND MUCH SOONER THAN THAT FOR THE LIMON AREA. WITH
COOLING TEMPS AND A LOWERING SUN ANGLE...THERE`S A BETTER FOR SNOW
ACCUMULATION ON THE PLAINS...AS WELL AS THE EAST FACE OF THE FRONT
RANGE DURING THIS PERIOD. HOWEVER ADDITIONAL SNOW AMOUNTS ON THE
FRONT RANGE AND SOUTH PARK WOULD NOT WARRANT HOLDING ONTO THE WINTER
STORM WARNING. A WINTER WEATHER ADVISORY WOULD SUFFICE. IT`LL STILL
RUN UNTIL 06Z TONIGHT. LASTLY ADDED FOG TO THE PLAINS AND FOOTHILLS
FORECAST FOR THE REMAINDER OF THE NIGHT. VSBYS ANYWHERE FROM A
QUARTER MILE TO 4 MILES THROUGH THE EVENING.

ON SATURDAY...MODELS SHOW THE UPPER LOW STILL IMPACTING NORTHEAST
COLORADO FOR MOST OF THE DAY. MOISTURE WRAPPING AROUND THE BACK SIDE
OF THIS LOW AND A COOL N-NWLY WIND SHOULD KEEP THE FCST AREA
UNSEASONABLY COOL AND UNSETTLED. QG VV FIELDS SHOW A LOBE OF MID-
LEVEL LIFT SWINGING DOWN FROM SERN WYOMING DURING THE MORNING LIKELY
RESULTING IN AN UPTURN IN PRECIPITATION COVERAGE ACROSS THE NERN
PLAINS AND NRN FRONT RANGE. LIGHT SNOW ACCUMULATIONS A POSSIBILITY.
LATER IN THE DAY...THE CWA GRADUALLY COMES UNDER THE INFLUENCE OF
DRIER AIR AND SUBSIDENCE AS THE UPPER LOW CONTINUES TO PULL AWAY.
THERE PRECIP CHANCES SHOULD LIKEWISE DECREASE FROM SOUTHWEST TO
NORTHEAST DURING THE AFTERNOON. TEMPERATURES NEXT 24 HOURS WELL
BELOW AVERAGE WITH HIGH TEMPS ON SATURDAY GENERALLY 3-6 DEG F WARMER
THAN THOSE TODAY.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 415 PM MDT FRI APR 29 2016

THERE WILL BE A BREAK BETWEEN SYSTEMS SATURDAY NIGHT AND SUNDAY
MORNING. HOWEVER IT WILL REMAIN CLOUDY WITH LOTS OF MOISTURE AND A
SHALLOW UNSTABLE LAYER NEAR THE GROUND...SO A LOW CHANCE OF LIGHT
SHOWERS OR DRIZZLE IS IN ORDER. THERE MAY BE WIDESPREAD DRIPPINESS
BUT NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION. THERE WAS SOME
THOUGHT OF FREEZING DRIZZLE EARLIER...BUT IT APPEARS TEMPERATURES
WILL GENERALLY BE ABOVE FREEZING WITH WARM AND WET ROADS. IF THERE
WERE UPSLOPE WINDS I WOULD BE CONCERNED WITH A RIBBON OF
FOG/FREEZING DRIZZLE IN THE FOOTHILLS BUT IT LOOKS LIKE THIS WILL
NOT BE THE CASE.

THERE IS A LITTLE BETTER AGREEMENT AND DEFINITION OF A WAVE
PASSING OVER AND SOUTH OF US ON SUNDAY INTO MONDAY. THE BEST LIFT
SHOULD BE TO THE SOUTH...AND IS GENERALLY WEAK...BUT IT WILL BE
WORKING ON A PRETTY FAVORABLE ENVIRONMENT WITH PLENTY OF MOISTURE
AND A SHALLOW UNSTABLE LAYER. SO IT MAY NOT BE HARD TO GENERATE
WIDESPREAD LIGHT PRECIPITATION AGAIN. RAISED POPS FOR THIS
PERIOD...NOT READY TO COMMIT TO THE WIDESPREAD PRECIPITATION
EVERYWHERE YET. TEMPERATURES SHOULD BE A LITTLE WARMER THAN THEY
ARE NOW AND PRECIPITATION SHOULD BE LIGHTER...SO THERE SHOULD BE LESS
IMPACT THAN WHAT WE ARE SEEING TODAY. STILL PROBABLY SOME SNOW
THOUGH...AT LEAST ABOVE 5000 FEET. THERE ARE TIMING DIFFERENCES ON
THE CLEARING OF THIS SYSTEM ON MONDAY...TRENDS ARE TOWARD MOVING
THE HIGHER LEVEL LIFT OUT EARLY MONDAY BUT WITH LOW LEVEL MOISTURE
LINGERING MUCH OF THE DAY.

A RIDGE WILL BUILD OVER US FOR THE REST OF THE WEEK. A WRINKLE
THAT DEVELOPED IN LAST NIGHTS ECMWF IS PERSISTING TODAY...A LOW
THAT DEVELOPS OVER SASKATCHEWAN AND DROPS INTO THE WESTERN U.S.
IF THIS DOES OCCUR...AND IT IS A MINORITY OPINION...IT IS PROBABLY
NOT MUCH OF A WEATHER MAKER BUT COULD HOLD BACK THE WARMING AND
GENERATE SOME CLOUD COVER...MAINLY AFFECTING TUESDAY AND
WEDNESDAY. PRETTY WARM BY THE END OF THE WEEK...WE COULD BE BACK
NEAR 80. THERE IS INCREASING CONSENSUS ON A BIG LOW MOVING INTO
THE WEST FOR NEXT WEEKEND...SO WE COULD BE BACK TO COOL AND WET BY
SUNDAY. WAY TOO EARLY FOR ANY CONFIDENCE OR DETAILS YET...A
PACIFIC SYSTEM WOULD PROBABLY NOT BE REAL COLD...LIKELY WARMER
THAN THE CURRENT SYSTEM.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 817 PM MDT FRI APR 29 2016

SNOW APPEARS TO HAVE COME TO AN END OVER THE DENVER AREA
AIRPORTS FOR THE EVENING...BUT CONTINUING WEAK NORTHERLY FLOW AND
A VERY MOIST AIRMASS WILL LEAD TO THE FORMATION OF FOG DURING THE
OVERNIGHT HOURS. VISIBILITIES COULD DROP TO A HALF MILE OR LESS AT
TIMES. FOG IN THE MORNING WILL GIVE WAY TO SOME MORE RAIN OR SNOW
SHOWERS BY MIDDAY AS DAYTIME WARMING CAUSES THE AIRMASS TO BECOME
SLIGHTLY UNSTABLE.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...DANKERS
SHORT TERM...BAKER
LONG TERM...GIMMESTAD
AVIATION...DANKERS


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