Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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000
FXUS65 KBOU 011701
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1001 AM MST MON FEB 1 2016

.UPDATE...
ISSUED AT 1000 AM MST MON FEB 1 2016

RADAR AND SATELLITE TRENDS SHOW A SUDDEN BLOSSOM OF PRECIPITATION
AS EXPECTED THIS MORNING...RIGHT AS WIND PROFILE TURNS MORE
EASTERLY. SNOW INTENSITY WILL CONTINUE TO INCREASE THROUGH THE
AFTERNOON AS THE EASTERLY FLOW DEEPENS AND STRENGTHENS...AND AS
AIRMASS BECOMES A LITTLE LESS STABLE THROUGH 600 MB. THIS SHOULD
ALLOW FOR MORE EFFICIENT SNOW PRODUCTION AND HIGHER ACCUMULATION
RATES WITH FAVORABLE PROFILE FOR DENDRITIC CRYSTAL GROWTH. ROAD
CONDITIONS WILL LIKELY DETERIORATE RAPIDLY WITH THE ONSET OF
HEAVIER SNOWFALL MAKING FOR A DIFFICULT AFTERNOON AND EVENING
COMMUTE. TRAVEL CONDITIONS WILL REMAIN POOR THROUGH TUESDAY
MORNING WITH SNOW ONLY GRADUALLY TAPERING OFF IN INTENSITY AFTER
MIDNIGHT. STILL EXPECT SOME LIGHT SNOW IN THE AREA FOR THE TUESDAY
MORNING COMMUTE. TOTAL ACCUMULATIONS WERE ALREADY ADJUSTED FOR THE
LACK OF SNOW LAST NIGHT AND EARLIER THIS MORNING AND THAT SEEMS
FINE. FORECAST TOTALS WILL REMAIN RELATIVELY UNCHANGED. IN
FACT...SOME OF THE LATEST DATA SHOWS POTENTIAL FOR A BIT HEAVIER
SNOWFALL THIS AFTERNOON/EVENING AS THE STORM TRACK IS QUITE
FAVORABLE FOR HEAVY SNOW. THE UPPER LOW IS CURRENTLY LOCATED RIGHT
NEAR THE FOUR CORNERS AND SPINNING EASTWARD...EVENTUALLY EXPECTED
TO TRACK ACROSS THE SOUTHEAST TIP OF COLORADO INTO SOUTHWEST
KANSAS LATE TONIGHT. THERE MAY BE A PERIOD OF 1 INCH PER HOUR
SNOWFALL RATES ON THE PLAINS GIVEN THE STRONG EASTERLY FLOW AND
MID LEVEL SPEED CONVERGENCE AIDING VERTICAL MOTION.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM MST MON FEB 1 2016

CURRENT STORM HEADING TOWARDS COLORADO IS CENTERED OVER NORTHERN
ARIZONA AND SOUTHERN UTAH. MODELS ARE IN GOOD AGREEMENT WITH THIS
CURRENT CIRCULATION LIFTING NORTHWEST INTO NORTHWEST COLORADO BY
18Z. THE MAIN STORM REFORMS OVER SOUTHEAST COLORADO/NORTHEAST NEW
MEXICO THIS EVENING. THERE ARE SLIGHT DIFFERENCES AMONG THE MODELS
WITH THE 00Z GFS BEING SLIGHTLY MORE NORTH THAN THE REST OF THE
MODELS. AGREE WITH WPC`S THINKING OF BLENDING THE STORM TRACK WITH
THE GFS AND ECMWF WITH A PREFERENCE CLOSER TOWARDS THE ECMWF.

NOW FOR THE DETAILS...SURFACE OBSERVATIONS AND SATELLITE INDICATE
THE LOW OF OVER SOUTHEAST UTAH AND IS A LITTLE DEEPER THAN MODELS
ARE SHOWING. MODELS ARE IN GOOD AGREEMENT WITH THIS LOW LIFTING
INTO NORTHWEST COLORADO BY 18Z. SOUTHERLY WINDS JUST OFF THE
SURFACE OVER EASTERN COLORADO WILL TURN EASTERLY WITH AS LOW
REACHES COLORADO. ONCE WINDS TURN EASTERLY...EXPECT WIDESPREAD
SNOW TO FORM MID TO LATE MORNING. EASTERLY UPSLOPE WINDS COMBINED
WITH LARGE SCALE ASCENT FROM THE APPROACHING LOW WILL KEEP
WIDESPREAD SNOW GOING THROUGH THE AFTERNOON.

WINDS TURN NORTHEAST THEN NORTHERLY THIS EVENING AS THE MAIN LOW
FORMS OVER SOUTHEAST COLORADO/NORTHEAST NEW MEXICO. IT THEN LIFTS
INTO KANSAS OVERNIGHT. LARGE SCALE LIFT FROM THE LOW AND BEST
UPSLOPE WILL BE THIS EVENING. SNOW WILL GRADUALLY DECREASE LATE
THIS EVENING AND AFTER MIDNIGHT.

NOT MUCH CHANGE TO THE CURRENT SNOW FORECAST. TOTALS COME IN A
COUPLE INCHES LOWER DUE TO THE LACK OF SNOW THIS MORNING. THE BULK
OVER SNOW WILL OCCUR LATE THIS MORNING THROUGH THE EVENING.

DON`T BE FOOLED BY THE LACK OF SNOW THIS MORNING. SNOW WILL
INCREASE MID MORNING AND BY LATE MORNING SNOW WILL BE WIDESPREAD
ACROSS THE AREA. SNOW WILL CONTINUE THROUGH THE AFTERNOON AND
EVENING. ROADS CONDITIONS WILL DETERIORATE LATE THIS MORNING AND
AFTERNOON. IF COMMUTING THIS MORNING...EXPECT MUCH WORSE
CONDITIONS FOR YOUR RETURN TRIP HOME.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 350 AM MST MON FEB 1 2016

A NEARLY VERTICALLY STACKED LOW SPINNING OVER W-CNTRL/SWRN KANSAS
EARLY TUESDAY MORNING IS PROGGED BY THE NAM..GFS..ECMWF..UKMET..WRF
AND CANADIAN MODELS TO TRACK NORTHEAST REACHING IOWA BY LATE IN THE
DAY. BEFORE LOOSING ITS GRIP ON ERN COLORADO NORTHERLY 700-500MB
MEAN FLOW OF 30-45KTS ON THE BACK SIDE OF THIS LOW IS FORECAST TO
PRODUCE 20-30KT N-NELY SFC WINDS ACROSS EASTERN SECTIONS OF THE CWA
DURING THE MORNING HOURS. GUIDANCE INDICATES STRONGEST WIND SPEEDS
WITHIN OUR CWA ACRS WASHINGTON...ERN ELBERT AND LINCOLN COUNTIES
WHERE CONSIDERABLE BLOWING AND DRIFTING SNOW IS A GOOD BET. VERY LOW
VSBYS DUE TO BLOWING SNOW AND WND SPEEDS APPROACHING 40 MPH MAY
WARRANT THE ISSUANCE OF A SHORT FUSE BLIZZARD WARNING FOR THIS 3
COUNTY AREA SHOULD LATER GUIDANCE CONTINUE TO INDICATE THIS
OCCURRING. IN ADDITION...LIGHT SNOWFALL IS LIKELY TO CONTINUE IN THE
MTNS...OVER AND ALONG THE PALMER DIVIDE AND OUT ACRS FAR ERN
SECTIONS OF THE CWA TUESDAY MORNING WITH A FAIR AMOUNT OF LOW/MID-
LEVEL MOISTURE CONTINUING TO WRAP BACK INTO THE STATE. COULD SEE
ANOTHER COUPLE INCHES OF SNOW IN THE FRONT RANGE FOOTHILLS AND
PALMER DIVIDE BY MIDDAY...WITH UPWARDS OF ANOTHER INCH IN THE
GREATER DENVER METRO AREA...AND LIGHT AMOUNTS ELSEWHERE. SNOW
CHANCES ON THE PLAINS SHOULD THEN QUICKLY DECREASE FROM NORTH TO
SOUTH AS DRIER DRY SPREADS DOWN FROM WYOMING ON LIGHTER NORTH-
NORTHWESTERLY WINDS. FOR THE HIGH COUNTRY...A NORTHWESTERLY FLOW
SHOULD CONTINUE TO GENERATE LIGHT OROGRAPHICALLY ENHANCED SNOWFALL
INTO THE EVENING HOURS WITH NEW ACCUMULATIONS ON THE LIGHT SIDE.
WILL HOLD ONTO THE WINTER STORM WARNING FOR THE MTNS AND PLAINS
WHICH EXPIRES AT 19Z/TUESDAY FOR THE TIME BEING. ALTHOUGH IT MAY BE
PULLED SOONER SHOULD THE LOW LIFT OUT FASTER THAN EXPECTED.
TEMPERATURES ON TUESDAY COLDEST OF THE WEEK WITH HIGHS IN THE UPPER
TEENS/20S ON THE PLAINS AND SINGLE DIGITS/TEENS IN THE HIGH COUNTRY.

FOR THE REMAINDER OF THE WEEK...A SWIFT NORTHWEST FLOW ALOFT IS
EXPECTED TO PRODUCE WINDY PERIODS FOR AREAS IN AND NEAR THE NORTHERN
FRONT RANGE AND ALONG THE NORTHERN BORDER WEDNESDAY AND THURSDAY...
AND A SLIGHT CHANCE OF SNOW IN THE HIGH COUNTRY. SHOULD SEE LITTLE
MODERATION IN TEMPERATURE DURING THIS PERIOD WITH READINGS REMAINING
SEVERAL DEGS BELOW AVERAGE. LATER IN THE WEEK...SHORTWAVE RIDGING
OVER THE STATE ON THURSDAY WILL WARM TEMPS AND DECREASE WINDS. BY
FRIDAY...MODELS INDICATE A PROGRESSIVE SHORTWAVE SWINGING ACROSS THE
STATE. GFS SHOWS A WETTER AND FASTER SYSTEM. OTHER MODELS A DRIER
AND SLOWER WAVE. WILL GO WITH A COMPROMISE AND TREND TOWARDS MORE
CLOUDS AND INTRODUCE LOW POPS MAINLY FOR THE HIGH COUNTRY. SATURDAY
LOOKS DRY AND WARMER AND SUNDAY COLDER WITH AN ALBERTA CLIPPER
RACING ACRS THE STATE DURING THE DAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1000 AM MST MON FEB 1 2016

SNOW IS INCREASING AS EXPECTED AND WILL CONTINUE THROUGH THE
AFTERNOON AND TONIGHT. MODERATE SNOWFALL IS EXPECTED TO PREVAIL
FROM 19Z-06Z WITH SURFACE VISIBILITY AVERAGING AROUND 1/2SM AND
CEILINGS/VERTICAL VISIBILITY UNDER 600 FEET. THEN EXPECT A GRADUAL
DECREASE IN SNOW INTENSITY AND INCREASE IN VISIBILITY 06Z-
15Z...WITH SNOW ENDING TOWARD 18Z TUESDAY. TOTAL SNOW
ACCUMULATIONS STILL EXPECTED TO RANGE FROM 7 TO 12 INCHES AT MOST
AIRPORTS. EAST TO NORTHEAST WINDS WILL INCREASE TO 15 TO 25 MPH
AND TURN MORE NORTHERLY WITH A FEW GUSTS TO 30 MPH EAST OF I-25
INCLUDING KDEN THIS AFTERNOON AND TONIGHT. THIS WILL PRODUCE SOME
BLOWING/DRIFTING SNOW.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON MST TUESDAY FOR COZ033>051.

&&

$$

UPDATE...BARJENBRUCH
SHORT TERM...MEIER
LONG TERM...BAKER
AVIATION...BARJENBRUCH


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