Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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 160155
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
755 PM MDT WED APR 15 2015

.UPDATE...
ISSUED AT 749 PM MDT WED APR 15 2015

LOOKING THE AT WRF FM THIS AFTN...LOOKS LIKE ENOUGH INSTABILITY
WILL BE AROUND TO PRODUCE MORE THUNDERSTORMS OVER THE NORTHEAST
PLAINS...MAINLY EAST OF A LINE FROM STERLING TO CASTLE ROCK SO
ADDED A SLGT CHC OF THUNDERSTORMS TO THOSE AREAS THURSDAY AFTN.
SEE FIRE WEATHER DISCUSSION BELOW.

UPDATE ISSUED AT 628 PM MDT WED APR 15 2015

HAVE UPDATED TO BACK OFF THE POPS ESPECIALLY OVER THE SRN HALF OF
THE CWFA THIS EVENING. THE RUC AND THE HRRR SHIFT MUCH OF THE
PCPN NORTH OF THE CWFA THIS EVENING THEN BRING IT BACK TOWARDS 12Z
THURSDAY MORNING. HAVE ALSO INCREASED THE WINDS OVER THE NORTHEAST
PLAINS THIS EVENING.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 238 PM MDT WED APR 15 2015

A SURFACE LOW OVER NORTHEAST COLORADO WILL MOVE EASTWARD OVERNIGHT
PULLING A COLD FRONT THROUGH EASTERN COLORADO THIS EVENING. LOW
LEVEL MOISTURE WILL INCREASE BEHIND IT. EXPECT SOME SHOWERS AND
PERHAPS A FEW THUNDERSTORMS TO FORM. BEST LIFT IS CURRENTLY OVER
LARIMER COUNTY AND INTO WYOMING AND WILL SHIFT NORTH THIS EVENING.
THEREFORE WILL KEEP POPS MAINLY IN TO 20 TO 60 PERCENT RANGE. THE
LOWER POPS WILL BE OVER LINCOLN COUNTY WHERE DRY AIR RESIDES NOW.
OVER THE NORTHEAST CORNER OF THE STATE...THERE MAY BE ENOUGH SHEAR
AND INSTABILITY TO PRODUCE A BRIEF SEVERE THUNDERSTORM.

EXPECT SHOWERS TO DECREASE LATE THIS EVENING AS SUBSIDENCE MOVES
OVER NORTHEAST COLORADO. STILL PLENTY OF MOISTURE IN PLACE BEHIND
THE FRONT...THUS WILL KEEP LOW CHANCES IN THE FORECAST THROUGH THE
NIGHT. ACTIVITY IS EXPECTED TO INCREASE THURSDAY MORNING AS UPPER
LEVEL LOW REACHES THE FOUR CORNERS AND AN EASTERLY UPSLOPE FLOW
INCREASES. BY LATE AFTERNOON EASTERLY UPSLOPE WINDS UP TO 30 KNOTS
WILL PREVAIL. THIS COMBINED WITH THE LIFT FROM THE LOW IS EXPECTED
TO PRODUCE WIDESPREAD RAIN AND SNOW BY LATE AFTERNOON. WITH THIS
SYSTEM LOOKING MORE CERTAIN WITH A GOOD CHANCE FOR HEAVY
SNOW...UPGRADED THE WINTER STORM WATCH TO A WARNING. WITH SNOW
EXPECTED TO BEGIN THURSDAY AFTERNOON MOVED UP THE TIME OF THE
WATCH.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 238 PM MDT WED APR 15 2015

MODELS STILL SHOW DECENT AGREEMENT WITH UPPER LEVEL CLOSED LOW
OVER THE FOUR CORNERS REGION THURSDAY NIGHT UNTIL ABOUT 12Z ON
FRIDAY. DYNAMICS ARE PROMISING WITH FAVORABLE MID LEVEL LAPSE
RATES AND QG BETWEEN -30 AND -35 MB/HR AT BOTH THE 500 AND 700 MB
LEVELS. SURFACE LOW WILL STRENGTHEN OVER THE EASTERN PORTION OF
THE STATE INCREASING MOISTURE ALONG THE FOOTHILLS WITH ONGOING
UPSLOPE EASTERLY FLOW THROUGH 00Z SATURDAY. THIS WILL HELP TO KEEP
PRECIPITATION OVER THE REGION THROUGH THE DAY FRIDAY. THE BIG
QUESTION STILL REMAINS ON WHERE THE SNOW WILL FALL VS RAIN/SNOW VS
RAIN. CURRENTLY MODELS ARE STILL INDICATING A RAIN AND SNOW
MIXTURE OVER MUCH OF THE FRONT RANGE URBAN CORRIDOR AND OUT TO DIA
WITH PREDOMINATELY RAIN FURTHER EAST OVER THE PLAINS. WITH PROFILE
TEMPERATURES COOLING CLOSER TO THE FOOTHILLS SNOW WILL DOMINATE
WITH INCREASING FROZEN PRECIPITATION ACCUMULATION ALONG THE
FOOTHILLS...MOUNTAINS AND PALMER DIVIDE AREA. WE COULD SEE
RAIN/SNOW TURNING MORE TO SNOW FRIDAY MORNING AS THE ATMOSPHERE
COOLS...INCREASING SNOWFALL AMOUNTS OVER DENVER INTO THE 1-4 INCH
RANGE. IF A BATCH OF COOLER AIR DOES MAKE ITS WAY INTO THE REGION
SNOW FALL AMOUNTS COULD GO UP FROM THESE VALUES.

FRIDAY NIGHT INTO SATURDAY THERE IS STILL SOME CONTENTION AMONGST
THE MODELS IN REGARDS TO THE UPPER LOWS PATH. THE 12Z GFS BRINGS
THE UPPER LOW CENTER NORTH TOWARD THE WY BORDER. THE NAM AND 00Z
EC KEEPS THE LOW CENTERED MORE SOUTH OVER THE SOUTHERN CO AND NM
BORDER. THE LATTER SET UP WILL ALLOW FOR PRECIPITATION TO LINGER
OVER THE PLAINS THROUGH SATURDAY WITH THE FORMER GFS ROUTE TO END
IT EARLIER SATURDAY MORNING. TEMPERATURES ON FRIDAY WILL BE COOL
OVERNIGHT WITH LOWS AROUND FREEZING AND HIGH TEMPERATURES IN THE
LOWER 50S WITH 20S AND 30S FOR THE MOUNTAINS.

PRECIPITATION WILL REMAIN A THREAT IN THE FOOTHILLS AND MOUNTAINS
THROUGH FRIDAY WITH OVER A FOOT POSSIBLE AND UP TO 2 FEET IN SOME
AREAS. WILL MAINTAIN CURRENT WATCH BUT WILL LOOK AT STARTING A BIT
EARLIER...POSSIBLY BY THURSDAY AFTERNOON AS MODELS INDICATE
SIGNIFICANT PRECIPITATION BY THIS TIME. MODELS ARE STILL
INDICATING INCREASED QPF AMOUNTS OF UP TO 2 INCHES OVER THE PLAINS
WITH SOME AREAS CLOSER TO THE FOOTHILLS RECEIVING UP TO 3
INCHES...MOST LIKELY A MIXTURE OF RAIN AND VERY WET SNOW.

BY SATURDAY NIGHT INTO SUNDAY THE UPPER LEVEL LOW IS PROGGED TO
MOVE OFF TO THE EAST OF THE REGION. THERE IS LITTLE RELIEF AS A
SECONDARY PUSH OF COOLER AIR MOVES INTO NORTHERN CO FROM THE NW.
EC HAS FAVORABLE QG ASCENT FOR SUNDAY WITH INCREASED MOISTURE IN
THE MORNING. WITH THE MOISTURE AND DYNAMICS IT WILL BE POSSIBLE TO
SEE ANOTHER ROUND OF PRECIPITATION ON SUNDAY. 700MB MODEL TEMPS
INDICATE A POSSIBLE CHANCE OF SNOW BY THE AFTERNOON WITH THE
AIRMASS COOLING IN THE LOWER LEVELS. TEMPERATURES ON SUNDAY WILL
BE IN THE UPPER 40S TO LOWER 50S WITH OVERNIGHT TEMPS AROUND
FREEZING ONCE AGAIN FOR THE DENVER AREA.

SUNDAY NIGHT INTO MONDAY ANOTHER DISTURBANCE IN THE UPPER LEVEL
FLOW WILL CONTINUE TO KEEP NE CO UNDER A SLIGHT CHANCE OF
PRECIPITATION WITH ANOTHER FRONT. HIGH TEMPERATURES WILL REMAIN IN
THE LOWER 50S. ON TUESDAY THE PATTERN WILL STAY ACTIVE WITH
ANOTHER DISTURBANCE MOVING THROUGH IN NORTHWESTERLY FLOW ALOFT.
THE MODELS DIVERGE THIS LATE IN THE FORECAST PERIOD SO WILL KEEP
POPS MODEST UNTIL LATER MODEL RUNS.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z THURSDAY EVENING)
ISSUED AT 628 PM MDT WED APR 15 2015

CEILINGS WILL LOWER TO 3000 TO 6000 FEET LATER THIS EVENING
BEHIND A COLD FRONT. GUSTS OF 30-35 KTS STILL POSSIBLE OVER THE
NEXT HOUR OR SO THEN THEY SHOULD DECREASE. NORTHERLY WINDS ARE
EXPECTED TO CONTINUE THROUGH TONIGHT AND INTO THURSDAY. WITH THE
STORM SYSTEM APPROACHING...EXPECT CEILINGS TO REMAIN BELOW 3000
FEET LATE TONIGHT AND THURSDAY. CEILINGS BELOW 1000 FEET WILL BE
POSSIBLE THURSDAY. BEST CHANCE FOR SHOWERS WILL BE LATE TONIGHT
AFTER 09Z...WITH SNOW IN THE 12-15Z TIME FRAME THURSDAY MORNING.
NO SNOW ACCUMULATION IS EXPECTED. RAIN IS EXPECTED TO BECOME
PERSISTENT LATE THURSDAY MORNING OR EARLY AFTERNOON. RIGHT NOW
LOOKS TOO WARM FOR SNOW THURSDAY AFTERNOON. HOWEVER SNOW WILL BE
POSSIBLE THURSDAY NIGHT AND FRIDAY WITH UP TO 6 INCHES POSSIBLE AT
KAPA AND KBJC...LIGHTER AMOUNTS ARE EXPECTED AT KDEN.


&&

.FIRE WEATHER...
ISSUED AT 749 PM MDT WED APR 15 2015

ALTHOUGH THE AMS OVER SOUTHERN LINCOLN COUNTY IS STILL QUITE DRY
...IT WILL CHANGE QUICKLY WITH THE PASSAGE OF THE COLD FRONT. THE
FRONT WILL BE MOVING THROUGH THE AREA IN THE NEXT HOUR OR SO.
DEWPOINTS IN THE LOWER 30S BEHIND THE FRONT ALLOWED THE RELATIVE
HUMIDITIES TO JUMP FOR THE SINGLE DIGITS AT LIMON AND HUGO...TO
AROUND 50 PERCENT IN 15 MINUTES. WITH THIS IN MIND...WL ALLOW THE
RED FLAG WARNING FOR FIRE WEATHER ZONE 247 TO EXPIRE AT 8 PM MDT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...

WINTER STORM WARNING FROM NOON THURSDAY TO 6 AM MDT SATURDAY FOR
COZ033>036.

&&

$$

UPDATE...COOPER
SHORT TERM...MEIER
LONG TERM...BOWEN
AVIATION...COOPER/MEIER
FIRE WEATHER...COOPER



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