Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 301642
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1042 AM MDT THU APR 30 2015

.UPDATE...
ISSUED AT 1042 AM MDT THU APR 30 2015

NO CHANGES TO THE FORECAST NEEDED AT THIS TIME. MODEL QPF FIELDS
CONTINUE TO SHOW CONVECTIVE SHOWERS DEVELOPING OVER THE MOUNTAINS
THIS AFTERNOON AND SPREADING ONTO THE PLAINS. MODEL SOUNDINGS FROM
THE NAM SHOW MODEST AMOUNTS OF CONVECTIVE AVAILABLE POTENTIAL
ENERGY AROUND 700-1000 J/KG. TEMPERATURES ON THE PLAINS ARE
ALREADY INTO THE LOWER 70S...SO THE FORECAST FOR UPPER 70S AND
AROUND 80 LOOKS GOOD. WITH THE MODEST AMOUNTS OF CAPE AND WEAK
WIND FLOW...THE THUNDERSTORMS THAT DEVELOP WILL BE WEAKLY
ORGANIZED...MEANING THAT BRIEF HEAVY RAIN...SMALL HAIL AND GUSTY
WINDS WILL BE THE MAIN THREAT. THE SURFACE COLD FRONT IS STILL NOT
EXPECTED TO ARRIVE UNTIL AFTER 6 PM.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 335 AM MDT THU APR 30 2015

HIGH PRESSURE RIDGE ALOFT STILL IN CONTROL OVER COLORADO EARLY
THIS MORNING BUT WE ARE LOOKING FOR A CHANGE IN THE WEATHER BY
LATER THIS AFTERNOON AND TONIGHT. WE WILL STILL HAVE A WARM
AFTERNOON BEFORE THE FRONT AS TEMPERATURES CLIMB IN THE THE UPPER
70S AND NEAR 80 OVER THE PLAINS. AN UPPER LEVEL TROF AND COLD
FRONT WILL MOVE ACROSS NORTHERN COLORADO LATER THIS AFTERNOON AND
NIGHT WITH AN INCREASE CHANCE FOR SHOWERS AND THUNDERSTORMS.
INITIAL DEVELOPMENT WILL BE OVER MOUNTAINS AND HIGHER TERRAIN
EARLY AFTERNOON BEFORE SPREADING OVER THE PLAINS BY THIS EVENING.
BEST CHANCE FOR STORMS WILL BE THIS EVENING OVER THE FRONT RANGE
DUE TO FRONTAL INTERACTION WITH CONVECTION AND THEN SHIFTING EAST
AND SOUTH OVER THE PLAINS LATE EVENING AND TOWARDS MIDNIGHT.
EXPECT MOST OF THE STORMS TO BE UNDER SEVERE LIMITS DUE TO
MARGINAL WIND PROFILE ALOFT. THERE IS SOME DECENT CAPE OF 800 TO
1200 J/KG SO CERTAINLY COULD SEE SOME SMALL HAIL AND HEAVY RAIN
WITH THE STORMS.

BEHIND THE FRONT...LOW LEVEL MOISTURE INCREASES WITH SHALLOW
UPSLOPE...SO EXPECT SOME STRATUS/PATCHY FOG DEVELOP LATER TONIGHT
ESPECIALLY OVER THE FRONT RANGE. EXPECT MUCH OF THE SHOWERS WILL
HAVE DISSIPATED BEFORE SUNRISE FRIDAY AS SUBSIDENCE AND DRYING
FILTER IN FROM THE NORTHWEST.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 335 AM MDT THU APR 30 2015

WESTERLY FLOW ALOFT WILL REMAIN FRIDAY WHILE A SURFACE HIGH PUSHES
DOWN FROM GREAT PLAINS CAUSING UPSLOPE FLOW. THIS WILL LIKELY
LEAD TO SOME LOW CLOUDS AND POSSIBLE FOG ALONG AND ADJACENT TO THE
FRONT RANGE FOOTHILLS. EXPECTING THE CLOUDS TO STICK AROUND FOR
MOST OF THE DAY TO PRODUCE A COOLER DAY...WITH HIGHS IN THE UPPER
60S FOR THE PLAINS AND IN THE 50S AND 60S FOR THE MOUNTAINS.
SHOULD SEE SHOWERS DEVELOP MAINLY IN THE FRONT RANGE MOUNTAINS
LATE MORNING...THEN SPREAD ACROSS THE PLAINS IN THE EARLY TO MID
AFTERNOON. NAM SHOWING CAPES OF 750 TO 1000 J/KG OVER THE FRONT
RANGE AREA EARLY AFTERNOON WHILE THE GFS SHOWS 500-750 J/KG. WILL
LEAN TOWARD THE DRIER GFS AS NAM IS CURRENTLY TOO WET FOR INITIAL
CONDITIONS. SOME DIFFERENCES IN THE MODELS ALSO WHERE STORM
ACTION WILL MOVE TO IN THE EVENING...EITHER SOUTHEAST OR
NORTHEAST. WILL FOLLOW THE NAM`S LEAD WITH STORM MOTION TO THE
SOUTHEAST AND POSITION OF THE UPPER JET. WITH THESE CAPES...COULD
SEE SLIGHTLY STRONGER STORMS OVER THE METRO AREAS. HOWEVER WITH
PW VALUES AROUND 0.7 INCHES AND LIMITED SURFACE HEATING...WOULD
NOT COUNT ON SEVERE STRENGTH STORMS AT THIS TIME.

EXPECT DRYING AND WARMING SATURDAY AS SHORTWAVE RIDGE PASSES
OVERHEAD. STILL EXPECT SOME ISOLATED TO SCATTERED AFTERNOON AND
EVENING SHOWERS AND STORMS. TEMPERATURES WILL BE ABOUT 10 DEGREES
WARMER THAN FRIDAY OVER THE PLAINS WITH THE ABSENCE OF UPSLOPE
FLOW AND CLOUDS...AND JUST A FEW DEGREES WARMER IN THE MOUNTAINS.
SUNDAY WILL BE SIMILAR IN TEMPERATURES HOWEVER SHOULD SEE AN
INCREASE IN SHOWER AND STORM COVERAGE WITH AN ENERGY RIPPLE IN
THE SOUTHWEST FLOW ALOFT.

FOCUS THEN SHIFTS TO THE UPPER LOW TO MOVE ONSHORE OVER THE BAJA
PENINSULA MONDAY. THIS LOW IS PROGGED TO MOVE NORTHEAST OVER THE
AREA BY WEDNESDAY AS IT`S CAUGHT IN THE FLOW OF A LARGER LOW
PUSHING ONSHORE OVER THE PACIFIC NORTHWEST. GFS AND ECMWF
CONTINUING TO BE RELATIVELY CONSISTENT WITH THEIR SOLUTIONS. HAVE
INCREASED CHANCE OF PRECIPITATION SLIGHTLY OVER THE MON-WED TIME
FRAME INTO THE HIGH CHANCE CATEGORIES. HIGH TEMPERATURES WILL
BEGIN TO COOL WHILE LOW TEMPERATURE LEVEL OFF OR EVEN WARM DUE TO
THE EXPECTED CLOUD COVER. NO BIG COLD POOL EXPECTED WITH THIS
SYSTEM AS IT PUSHES IN FROM THE SOUTHWEST...THEREFORE SNOW LEVELS
ARE EXPECTED TO STAY AROUND 10KFT THROUGH WED.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z FRIDAY MORNING)
ISSUED AT 1042 AM MDT THU APR 30 2015

NO BIG CHANGES TO THE TAFS FORTHCOMING WITH THE NEW PACKAGE.
EVENING THUNDERSTORMS ARE STILL EXPECTED WITH GUSTY WINDS AND
BRIEF HEAVY RAIN. LATER TONIGHT...AREAS OF STRATUS OR FOG ARE
EXPECTED AFTER THE EVENING FRONTAL PASSAGE. ON FRIDAY
AFTERNOON...MODEL SOUNDINGS SHOW A MORE UNSTABLE AIRMASS WHICH
WILL NECESSITATE HAVING THUNDER DEVELOP BETWEEN 3 PM AND 6 PM.

&&

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

$$

UPDATE...DANKERS
SHORT TERM...ENTREKIN
LONG TERM...KRIEDERMAN
AVIATION...DANKERS



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