Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 190149
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
749 PM MDT SAT APR 18 2015

.UPDATE...
ISSUED AT 750 PM MDT SAT APR 18 2015

UPPER LEVEL LOW NOW OVER FAR EASTERN COLORADO AND WILL MOVE INTO
WESTERN KANSAS OVERNIGHT. THE SHOWERS AND THUNDERSTORMS HAVE
DECREASED THIS EVENING AS THE AIRMASS HAS STABILIZED SOME. STILL
EXPECT SHOWERS TO INCREASE OVERNIGHT ON THE BACKSIDE OF THE LOW.
WILL CONTINUE WITH HIGH POPS THIS EVENING AND OVERNIGHT. FOR THE
MOUNTAINS...FAVORED AREAS WILL SEE 3 TO 6 INCHES WITH LESS
ELSEWHERE. FOR THE FRONT RANGE AND EASTERN PLAINS...SNOW LEVEL
WILL START OFF ABOVE 6000 FEET...BUT LOWER OVERNIGHT AS THE
AIRMASS COOLS. COULD SEE AN INCH OR TWO OF SLUSHY ACCUMULATION
ALONG THE PALMER DIVIDE AND NEAR THE FOOTHILLS BY DAY BREAK. WINDS
WILL INCREASE TONIGHT AS THE LOW MOVES OFF. MAY SEE GUSTS OF 40 TO
50 MPH OVER THE PLAINS LATE TONIGHT AND EARLY SUNDAY. WILL
INCREASE WINDS IN THE FORECAST A LITTLE MORE. ON SUNDAY...EXPECT
DRIER AIR TO MOVE OVER THE PLAINS AND BRING THE SHOWERS TO AN END
DURING THE MORNING.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 322 PM MDT SAT APR 18 2015

UPPER LEVEL LOW HAS MADE VERY LITTLE EASTWARD PROGRESS TODAY AND
IS STILL LOCATED OVER SOUTHWEST WASHINGTON COUNTY...BASED ON THE
RECENT MOTION OF RADAR ECHOES. AFTERNOON HEATING AND COLD
TEMPERATURES ALOFT HAVE DE-STABILIZED THE AIRMASS ENOUGH FOR
EMBEDDED THUNDERSTORMS TO DEVELOP OVER THE FAR NORTHEAST PLAINS.
MOUNTAIN AREAS HAVE BEEN PICKING UP SCATTERED SNOW SHOWERS...BUT
NOT MUCH NEW SNOW ACCUMULATION...BASED ON WEB CAMERAS AND SNOTEL
DATA.

THE SHOWERS AND THUNDERSTORMS THIS EVENING SHOULD TAPER IN THE
EVENING...WITH THE LOSS OF DAYTIME HEATING. ADDITIONAL SHOWERS ARE
EXPECTED OVERNIGHT AS THE UPPER LOW MOVES EASTWARD AND THE RETURN
FLOW ON THE BACKSIDE OF THE LOW MOVES OUT OF THE MOUNTAINS AND
ACROSS THE PLAINS. THE NAM AND RAP FORECASTS HAVE RAIN OCCURRING
THROUGH MOST OF THE NIGHT AND THEN A DECREASE IN SHOWER ACTIVITY
BY MIDDAY SUNDAY. TEMPERATURES OVERNIGHT WILL DROP TO THE MID AND
UPPER 30S ON THE PLAINS WHICH MAY BE COOL ENOUGH FOR SOME SNOW TO
FALL. NO SIGNIFICANT ACCUMULATIONS ARE EXPECTED THOUGH. SUNDAY
WILL BE A MIX OF MORNING SHOWERS AND THEN DECREASING CLOUDS IN THE
AFTERNOON. STRONG INSOLATION SHOULD ALLOW AFTERNOON TEMPERATURES
TO CLIMB INTO THE LOWER 50S. MOUNTAIN AREAS COULD SEE SCATTERED
SNOW SHOWERS CONTINUE AS WE REMAIN UNDER MOIST NORTHWESTERLY FLOW.
SNOW ACCUMULATIONS SHOULD BE LESS THAN 3 OR 4 INCHES.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 322 PM MDT SAT APR 18 2015

A COLD NORTHWEST FLOW ON THE BACK SIDE OF EXITING
LONG WAY UPPER TROUGH DRIVES A CLIPPER TYPE DISTURBANCE SOUTHWARD
OUT OF WYOMING SUNDAY NIGHT AND MONDAY MORNING ACCORDING TO
DETERMINISTIC MODELS. SYSTEM APPEARS TO PACK ADJACENT COLD
AIR...MOISTURE AND OROGRAPHIC LIFT TO PRODUCE ANOTHER ROUND OF LIGHT
SNOW ACCUMULATION IN THE HIGHER MTN RANGES. MTN PASSES AND EXPOSED
NORTHWEST SLOPES COULD SEE ANYWHERE FROM 2-5 INCHES OF ADDITIONAL
SNOW ACCUMULATION BY MONDAY EVENING. WETBULB TEMP IS PROGGED TO BE
LOW ENOUGH FOR A RAIN/SNOW MIX ON THE NEAR BY PLAINS SUNDAY
EVENING...AND POSSIBLY ALL SNOW LATE SUNDAY NIGHT INTO MONDAY
MORNING. THIS SYSTEM DOES NOT LOOK LIKE A BIG PRECIP MAKER FOR THE
PLAINS AND ANY SNOW THAT FALLS AT LOWER ELEVATIONS SHOULD NOT
ACCUMULATE.

MODELS SHOW THIS DISTURBANCE QUICKLY MOVING OUT OF THE FCST AREA
DURING THE DAY MONDAY AND WITH LOW LEVEL WINDS TURNING WESTERLY...
TEMPS SHOULD MANAGE TO REACH THE 50S ON THE PLAINS WITH SUNSHINE
RETURNING LATE IN THE DAY.

MODELS SHOW A BREAK IN THE COOL AND WET NWLY FLOW PATTERN TUESDAY
INTO WEDNESDAY WHEN A DIRTY SHORTWAVE UPPER RIDGE OVER THE GREAT
BASIN WORKS ITS WAY ACROSS COLORADO. GFS AND NAM INDICATE A FAIR
AMOUNT OF MID AND HIGH LEVEL MOISTURE WITH THIS RIDGE...SUFFICIENT
TO WARRANT A CHANCE OF RAIN/SNOW SHOWERS IN THE HIGH COUNTRY ON
TUESDAY AND AGAIN BY WEDNESDAY AFTERNOON. LATE DAY SHOWERS ON
WEDNESDAY COULD BE ACCOMPANIED BY SOME THUNDER DURING THE WARMEST
TIME OF THE DAY. ON THE PLAINS...DRY CONDITIONS WILL PREVAIL WITH A
PREVAILING W-SWLY LOW LEVEL FLOW. AS A RESULT...TEMPS REBOUND WITH
AFTN READINGS 1-5 DEG F ABOVE AVERAGE ON TUES AND 5-10 DEG ABOVE
AVERAGE BY WED. LATE ON WEDNESDAY UPPER RIDGE OVER COLORADO APPEARS
TO FLATTEN OUT WITH MODELS SHOWING A WEAK SHORTWAVE TROUGH ZOOMING
UP FROM THE DESERT SOUTHWEST AND THEN ROUNDING THE TOP OF RIDGE.
SHOULD THIS HAPPEN...CAN SEE PRECIP CHANCES ON THE RISE AGAIN ACRS
THE CWA WITH RAIN/SNOW IN THE HIGH COUNTRY AND RAIN SHOWERS ON THE
PLAINS. THERE/S ALSO A SLIGHT CHANCE OF T-STORMS BY EVENING.

THURSDAY AND BEYOND...LARGE SCALE FLOW PATTERN OVER THE WESTERN
CONUS IS PROGGED TO BECOME MORE LIVELY WITH YET ANOTHER LARGE SCALE
UPPER TROUGH MAKING ITSELF FELT IN THE GREAT BASIN WEDNESDAY INTO
THURSDAY AND ACROSS THE NORTH CENTRAL AND NORTHEAST THURSDAY AND
FRIDAY. WITH AS MUCH MOISTURE AND COOL AIR WITH THIS SYSTEM...WILL
CONTINUE LOW POPS FOR ALL AREAS RIGHT THROUGH SATURDAY.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 750 PM MDT SAT APR 18 2015

SHOWERS AND THUNDERSTORMS HAVE DECREASED THIS EVENING AS THE
AIRMASS HAS STABILIZED. ADDITIONAL RAIN AND SNOW SHOWERS ARE
EXPECTED OVERNIGHT DUE TO LIFT FROM THE UPPER LEVEL LOW. LITTLE
TO NO SNOW ACCUMULATION IS EXPECTED. THE BEST CHANCE FOR SNOW
ACCUMULATION WILL BE AT KAPA. NORTHERLY WINDS WILL PREVAIL
THROUGH SUNDAY AND BE GUSTY AT TIMES WITH GUSTS TO 30 KNOTS
LATE TONIGHT AND SUNDAY. CEILINGS WILL FALL TO 1500 TO 3000 AS
THE SHOWER ACTIVITY PUSHES THROUGH. CEILINGS WILL THEN SLOWLY RISE
SUNDAY MORNING TO ABOVE 6000 FEET BY 20Z.

&&

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

$$

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


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