Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KBOU 211648
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1048 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 1048 AM MDT THU MAY 21 2015

MADE A FEW ADJUSTMENTS TO TIMING OF THE ONSET OF PRECIPITATION
THIS EVENING. PRECIPITATION EPISODE IS STILL EXPECTED...BUT NOT
UNTIL AFTER 8 OR 9 PM ACROSS THE PLAINS.

THIS MORNING...ADDED PATCHY FOG AND DRIZZLE TO THE FOOTHILL ZONES
WHERE WEB CAMS INDICATE POOR VISIBILITY ALONG THE I-70 CORRIDOR.
ALSO DECREASED SKY COVER OVER THE MOUNTAINS THIS MORNING...WHERE
SKIES ARE CURRENTLY SUNNY. HOWEVER...CLOUDS WILL BE INCREASING BY
EARLY AFTERNOON AND POPS WILL BE ON THEIR WAY UP.

WILL KEEP THE WINTER WEATHER ADVISORY IN ZONE 34 FOR TONIGHT AS
SNOW IS STILL EXPECTED...ESPECIALLY ABOVE 10 THOUSAND FEET.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 420 AM MDT THU MAY 21 2015

ANOTHER NIGHT OF STRATUS ON THE NORTHEAST PLAINS ALONG WITH PATCHY
FOG AND DRIZZLE ALONG THE FRONT RANGE. MOISTURE DEPTH BECOMES MORE
SHALLOW WITH TIME SO COULD SEE SOME PARTIAL CLEARING ON THE
PLAINS BY LATE MORNING. ALONG THE FRONT RANGE...DENVER CYCLONE
EXPECTED TO DEVELOP THIS AM WITH THE SOUTHEAST FLOW WHICH MAY HOLD
CLOUDS/FOG IN A BIT LONGER FOR LOCATIONS NORTH AND WEST OF
DENVER...PENDING EXACT LOCATION OF CONVERGENCE ZONE. GIVEN
ABUNDANT CLOUD COVER HAVE DROPPED HIGH TEMPERATURES A FEW DEGREES
ON THE PLAINS.

MAIN EVENT FOR NEXT 24 HOURS IS NEXT WAVE WHICH WILL EJECT
TOWARDS COLORADO LATER THIS AFTERNOON FROM THE PARENT LOW ACROSS
SOUTHERN CALIFORNIA. INCREASING QG ASCENT WITH STRONGEST FORCING
FROM THIS EVENING THROUGH 12Z FRIDAY. LATEST QPF FROM MODELS
INDICATE ANYWHERE FROM .25 TO .75 ON THE PLAINS AND UPWARDS OF AN
INCH IN THE MOUNTAINS. WILL CONTINUE TO INCREASE POPS ACROSS THE
BOARD. FOR THE MOUNTAINS...SNOW LEVEL WILL BE QUITE HIGH BUT
POTENTIAL FOR DECENT SNOWFALL OVER THE MOUNTAIN PASSES ABOVE 10500
FEET. HAVE OPTED TO ISSUE A WINTER WEATHER ADVISORY FOR 4-8 INCHES
OF SNOW FOR ZONE 34 WITH MAIN IMPACT OVER THE MOUNTAIN PASSES AND
VERY LITTLE SNOWFALL OVER VALLEY FLOORS. DECENT SOUTHEAST FLOW
WILL ENHANCE SNOWFALL ACROSS NORTHERN PARK COUNTY. HEAVIEST
SNOWFALL WILL BE FROM LATE AFTERNOON THROUGH TONIGHT.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 420 AM MDT THU MAY 21 2015

ON FRIDAY...BLOCKING LONGWAVE TROUGH WILL STILL BE OVER THE
INTERMOUNTAIN WEST WITH THE 500 MB LOW VICINITY OF LAS VEGAS AROUND
MIDDAY. STRONG SWLY FLOW ALOFT ROUNDING THE BOTTOM OF THE TROUGH IS
PROGGED TO BE CROSSING THE 4-CORNERS AND SRN COLORADO DURING THE
DAY. EMBEDDED IN THIS FLOW WAS A SHORTWAVE TROUGH WHICH MODELS SHOW
PASSING OVER NERN COLORADO EARLY IN THE MORNING. BEST MOISTURE AND
LIFT AHEAD OF THIS S/W SHOULD EXIT THE CWA AREA AS THE MORNING
PROGRESSES. HIGHER MTN PASSES COULD STILL PICK UP A COUPLE MORE
INCHES OF SNOW BY NOON. SHOULD ALSO SEE BACK EDGE OF SHOWERS ON THE
PLAINS EXITING THE AREA TO THE NORTHEAST WITH DRYING AND SUBSIDENCE
IN THE WAKE OF THE SHORTWAVE. HOWEVER...BY AFTERNOON WITH STRONG
SOLAR HEATING...INCREASING UPPER AIR DIFFLUENCE AND WET SOILS...
SHOULD SEE ANOTHER ROUND OF SHOWERS AND T-STORMS FORMING IN THE HIGH
COUNTRY AND ON THE ADJACENT HIGH PLAINS DURING THE AFTERNOON. WILL
STICK WITH 30-50 PCT PRECIP CHANCES ALREADY IN THE FCST FOR MOST
AREAS FRIDAY AFTERNOON. MOST OF THIS ACTIVITY SHOULD END DURING THE
EVENING. TEMPS ON FRIDAY LOOK TO BE 3-4 DEG C WARMER THAN THOSE ON
THURSDAY.

BY SATURDAY...THE MAIN UPPER TROUGH CONTINUES ITS SLOW EASTWARD
PROGRESSION WITH A MAJORITY OF THE DETERMINISTIC MODELS AND ENSEMBLE
MEMBERS SHOWING THE 500 MB LOW POSITIONED JUST NORTH OF THE 4-
CORNERS BY LATE AFTERNOON. SATURDAY LOOKS DRIER AND WARMER
PARTICULARLY EAST OF THE MTNS WITH MODELS SHOWING A DRY SOUTH-
SOUTHWESTERLY FLOW ALOFT OVER THE AREA. THEREFORE PRECIP CHANCES NOT
AS GREAT ON SATURDAY...ALTHOUGH STRONG DAYTIME HEATING AND MOIST
SOILS SHOULD AGAIN BE SUFFICIENT TO FUEL ISOLATED TO SCATTERED
SHOWERS AND ISOLATED TO SCATTERED T-STORMS MAINLY IN THE HIGH
COUNTRY AND ALONG THE NORTHERN AND EASTERN BORDERS OF THE CWA. THE
PROSPECT FOR SEVERE STORMS APPEARS LOW AT THIS TIME.

BY SUNDAY...MODELS SHOW THE UPPER TROUGH FINALLY MAKING ITS WAY
ACROSS THE THE REGION WHICH WILL INCREASE THE CHANCE FOR SHOWERS AND
T-STORMS FOR ALL AREAS BY MIDDAY IN THE HIGH COUNTRY AND BY LATER IN
THE AFTERNOON ON THE PLAINS AS IT LOOKS NOW. SFC CYCLOGENESIS UP NEAR
THE WY BORDER IN WELD COUNTY COULD ACT AS A FOCUS FOR A FEW STRONG
STORMS LATE AFTERNOON AND AND/OR EARLY IN THE EVENING. LOCALLY HEAVY
RAINFALL AND HAIL APPEARS TO BE THE MAIN THREATS. COULD SEE SHOWERS
LINGERING ALL NIGHT MAINLY EAST OF THE MTNS AS THE UPPER TROUGH
PASSES SLOWLY OVER THE AREA.

MEMORIAL DAY THROUGH WEDNESDAY...WILL REMAIN UNSETTLED AS A SERIES
OF WEAK SHORTWAVE DISTURBANCES IN A MOIST W-SWLY FLOW ALOFT MAKE
THEIR WAY ACRS THE REGION...APPROXIMATELY ONE A DAY. WILL KEEP DAILY
SHOWERS AND T-STORMS IN THE FCST THROUGH MID-WEEK AND TEMPERATURES
NEAR SEASONAL NORMS.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z FRIDAY MORNING)
ISSUED AT 1048 AM MDT THU MAY 21 2015

MOIST AIRMASS REMAINS ENTRENCHED OVER THE DENVER METRO AREA WITH
LOW CEILINGS AND AREAS OF FOG...DRIZZLE AND TERRAIN OBSCURATIONS
OVER THE FOOTHILLS. MINOR AND BRIEF IMPROVEMENT IS EXPECTED DURING
THE AFTERNOON HOURS AS SOME MID-LEVEL DRYING ADVECTS OVER THE I-25
CORRIDOR FROM THE MOUNTAINS. HOWEVER...ADDITIONAL UPPER LEVEL
MOISTURE WILL BE ARRIVING FROM THE SOUTHWEST BY LATE AFTERNOON AS
TONIGHTS UPPER LEVEL DISTURBANCE APPROACHES. AT LOW LEVELS HIGH
PRESSURE OVER KANSAS AND OKLAHOMA WITH LOWER PRESSURE OVER
COLORADOS WESTERN SLOPE WILL PRODUCE PERSISTENT AND MOIST
SOUTHEASTERLY FLOW ACROSS THE PLAINS. THIS WILL KEEP SKIES
OVERCAST FOR THE MOST PART WITH SOME IMPROVEMENT TO MVFR OR LOW
VFR CONDITIONS DURING THE AFTERNOON. CELINGS WILL LOWER AGAIN THIS
EVENING AS PRECIPITATION DEVELOPS DUE TO TONIGHTS PASSING UPPER
LEVEL DISTURBANCE. IFR AND MVFR WILL PREVAIL DURING THE OVERNIGHT
HOURS.

&&

.HYDROLOGY...
ISSUED AT 1048 AM MDT THU MAY 21 2015

HAVE DROPPED THE FLOOD WARNINGS ON THE SOUTH PLATTE DOWNSTREAM
FROM FORT MORGAN AS THE LEADING FLOOD CREST IS ATTENUATING. FLOOD
WARNINGS CONTINUE FOR THE SOUTH PLATTE FROM CENTRAL WELD COUNTY
INTO WESTERN MORGAN COUNTY. AT THIS TIME...GENERALLY MINOR
FLOODING IS ANTICIPATED WITH WATER LEVELS BELOW LAST WEEKS CREST.
CONITNUED MINOR FLOODING IS STILL ANTICIPATED ON THE CACHE LA
POUDRE IN WESTERN WELD COUNTY. THE FLOOD WARNING FOR THAT STRETCH
OF THE CACHE LA POUDRE NOW GOES UNTIL MONDAY.

ANOTHER ORGANIZED SHORTWAVE WILL MOVE THROUGH THE REGION TONIGHT
WITH MORE LIGHT TO MODERATE RAIN AND SOME EMBEDDED
THUNDERSHOWERS. TOTAL LIQUID PRECIPITATION IS EXPECTED TO RANGE
FROM .25 TO .75 INCHES ON THE PLAINS WITH UPWARDS OF AN INCH OVER
THE MOUNTAINS AND HIGHER FOOTHILLS. ALTHOUGH THESE ARE NOT
EXCEPTIONAL NUMBERS...THE SATURATED GROUND CONDITIONS SHOULD
RESULT IN EFFICIENT RUNOFF. EXPECT THE CONTINUATION OF HIGH FLOWS
IN RIVERS AND STREAMS THAT ARE ALREADY HIGH... AND POSSIBLY THE
DEVELOPMENT OF BANKFULL OR MINOR FLOODING IN OTHER STREAMS AND
RIVERS.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM MDT
FRIDAY FOR COZ034.

&&

$$

UPDATE...DANKERS
SHORT TERM...ENTREKIN
LONG TERM...BAKER
AVIATION...DANKERS
HYDROLOGY...ENTREKIN/DANKERS


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.