National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KBOU 211626
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1026 AM MDT MON APR 21 2014

.UPDATE...
ISSUED AT 1025 AM MDT MON APR 21 2014

CURRENT FORECASTS LOOK ON TRACK...ONLY MINOR CHANGES TO SKY AND
WIND GRIDS BASED ON CURRENT CONDITIONS. WEAK SURGE ASSOCIATED
WITH SURFACE PRESSURE IN EASTERN WYOMING PUSHED ACROSS PLAINS THIS
MORNING. AIRMASS SLIGHTLY COOLER AND MORE STABLE WITH SOUNDINGS
INDICATING WEAK MID LEVEL CAP IN PLACE OVER MUCH OF PLAINS.
AIRMASS TO BECOME A BIT UNSTABLE ACROSS THE ELEVATED TERRAIN THIS
AFTERNOON WITH DAYTIME HEATING...FORECAST SOUNDINGS INDICATING
CAPE VALUES AROUND 200 J/KG. ENOUGH MOISTURE TO GENERATE A FEW
THUNDERSTORMS ACROSS THE MOUNTAINS AND FOOTHILLS...LOOK TO BE
CONCENTRATED ALONG THE EAST SLOPES WITH HELP OF WEAK UPSLOPE.
PLAINS STILL APPEAR BIT TOO STABLE FOR ANY CONVECTION. EXCEPTION
MAY BE ALONG THE ELEVATED TERRAIN OF THE PALMER DIVIDE LATE IN THE
AFTERNOON. IT IS POSSIBLE A DYING STORM OR TWO COULD MAKE THEIR
WAY ONTO THE URBAN CORRIDOR LATE THIS AFTERNOON OR EARLY EVENING...MAY
WELL END UP JUST BEING AN BRIEF INCREASE IN CLOUD COVER. ONLY
LIGHT RAINFALL EXPECTED FROM THE STORMS WITH LOCALLY GUSTY WINDS.
LOW LEVEL JET STILL EXPECTED TO DEVELOP NEAR THE COLORADO KANSAS
BORDER THIS EVENING...COULD GENERATE GUSTY SOUTHERLY WINDS ACROSS
PORTIONS OF THE PLAINS.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 401 AM MDT MON APR 21 2014

SLIGHTLY COOLER AND MORE HUMID LOW-LEVEL AIR HAS PUSHED UP
AGAINST THE FRONT RANGE IN THE PAST COUPLE OF HOURS. NORTHEAST
SFC-700MB FLOW OVER NORTHEAST COLORADO EARLY THIS MORNING WAS THE
RESULT OF A TIGHT PRES GRADIENT CREATED BY A FAIRLY STRONG SFC
HIGH IN ERN WYOMING AND A SFC LOW IN WRN KANSAS. MODELS SHOW THIS
UPSLOPE FLOW ADVECTING HIGHER DEWPT AIR UP AGAINST THE FOOTHILLS
DURING THE NEXT FEW HOURS. HAVE SEEN AN INCREASE IN CLOUD COVER
ALONG AND EAST OF THE FRONT RANGE THIS INFLUX OF HUMIDITY...
ALTHOUGH CLOUDS WERE FORMING MAINLY AT MID-LEVELS WITH CURRENT
SFC DEWPOINT SPREADS IN EXCESS OF 5 DEG C. LATER THIS MORNING LOOK
FOR THIS UPSLOPE FLOW TO WEAKEN AS WINDS ON THE PLAINS SHIFT TO A
SOUTHEASTERLY COMPONENT WITH THE SFC HIGH SLIPPING INTO ERN
COLORADO. THE COOLER BOUNDARY LAYER AIR AND EARLY MORNING CLOUD
COVER SHOULD LIKELY INHIBIT CONVECTION ON THE PLAINS UNTIL LATE
THIS AFTERNOON. HOWEVER IT APPEARS MOST OF THE SHOWER DEVELOPMENT
TODAY WILL BE CONFINED TO THE FRONT RANGE AND HIGHER TERRAIN OF
THE CHEYENNE RIDGE WHERE STEEPER LAPSE RATES WILL EXIST. UPDRAFTS
TODAY WILL BE WEAK DUE IN LARGE PART TO A STRONG CAP UP AROUND
650 MBS...A PRODUCT OF STRONG WARMING ALOFT ASSOCIATED WITH AN
APPROACHING UPPER LEVEL RIDGE. SHOWERS THAT MANAGE TO FORM WILL
BE SPOTTY AND SHORT-LIVED. HIGH TEMPERATURES TODAY SLIGHTLY
COOLER THAN YESTERDAY BUT NEAR STILL SEASONAL NORMS. TONIGHT...
SKIES CLEAR WITH THE UPPER RIDGE MOVING OVER THE STATE. ON THE
PLAINS COULD SEE GUSTY SOUTH-SOUTHWESTERLY WINDS DEVELOPING MID TO
LATE EVENING...MAINLY EAST OF THE I-25 CORRIDOR. PRESSURE FALLS TO
OUR NORTH AND THE PRESENCE OF A LOW-LEVEL JET ALONG THE
COLORADO/KANSAS BORDER MAY RESULT IN GUSTS IN THE 20-25KT RANGE
OVER OPEN RANGELAND. THE GUSTY WINDS WILL RESULT MILD OVERNIGHT
TEMPERATURES.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 401 AM MDT MON APR 21 2014

THE NEXT UPPER TROF SHIFTS INTO THE NORTHERN GREAT BASIN ON
TUESDAY WITH INCREASING SOUTHWEST FLOW ALOFT OVER COLORADO.  AT
THE SURFACE THERE WILL BE A SURFACE LEE TROF DEVELOPING OVER
EASTERN COLORADO WITH INCREASING LOW LEVEL SOUTHERLY FLOW AND
HIGHER DEWPOINTS OVER THE COLORADO AND KANSAS BORDER AREAS. THIS
WOULD FOCUS POSSIBLE THUNDERSTORM DEVELOPMENT OVER FAR EASTERN
ZONES. AT THIS TIME LOOKS LIKE THE BEST CHANCE WOULD BE IN KANSAS.
CURRENT FORECASTS ALREADY SHOWING THESE AREAS AS FOCUS FOR
STORMS.  ELEVATED FIRE DANGER EXPECTED OVER PORTIONS OF THE
PLAINS TUESDAY AND WEDNESDAY AFTERNOON AS GUSTY WINDS DEVELOP BUT
THERE IS SOME QUESTION ON HOW LOW HUMIDITY LEVELS DROP. FOR
NOW...HUMIDITY LEVELS ARE NOT LOW ENOUGH TO JUSTIFY ANY FIRE
WEATHER WATCHES.

THE OTHER CHANCES OF PRECIP WOULD BE FURTHER WEST OVER THE
MOUNTAINS WHERE THERE IS SOME MOISTURE TO WORK WITH WITH APPROACH
OF TROF. THE BROAD UPPER TROF AND ASSOCIATED COLD FRONT WILL
SWEEP ACROSS THE REGION ON WEDNESDAY AND WEDNESDAY NIGHT WITH
AGAIN THE BEST CHANCES OF PRECIP OVER THE MOUNTAINS AND FAR
NORTHEAST COLORADO. OVERALL THE BRUNT OF THIS STORM WILL BE NORTH
OF COLORADO AS MOISTURE IS RATHER SCARCE AND QG FORCING IS
MINIMAL. THURSDAY AND FRIDAY WILL BE DRY AS WEAK RIDGING ALOFT
MOVES OVER THE AREA WITH SEASONAL TEMPERATURES.

THE WEEKEND LOOKS INTERESTING AS THE GFS SHOWING A RATHER STRONG
UPPER TROF WHICH CLOSES OFF OVER SOUTHEAST COLORADO ON SUNDAY.
STRONG AND MOIST SOUTHEAST LOW LEVEL FLOW DEVELOPS AHEAD OF THE
LOW. HOWEVER...NOT PUTTING A LOT OF FAITH IN ANY ONE SCENARIO AT
THIS POINT. GFS ENSEMBLE MEMBERS HAVE THE LOW VARYING FROM ARIZONA TO
SOUTH DAKOTA. THE EUROPEAN SOLUTION IS NOT NEARLY AS DEEP WITH
THE LOW FURTHER NORTH OF COLORADO. WILL ONLY MAKE SLIGHT CHANGES
TO THE WEEKEND FORECAST WITH SLIGHTLY HIGHER POPS AND LOWER
TEMPERATURES. IF THE GFS WOULD TO VERIFY IT WOULD BE A SIGNIFICANT
PRECIP EVENT OVER CWA WITH SNOW IN THE MOUNTAINS AND RAIN AND SNOW
ACROSS LOWER ELEVATIONS.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z TUESDAY AFTERNOON)
ISSUED AT 1025 AM MDT MON APR 21 2014

OVERALL CURRENT TAF TRENDS LOOK REASONABLE. WINDS BECOMING MORE
EAST SOUTHEAST ACROSS THE AREA AIRPORTS AS SURFACE HIGH MOVES INTO
NORTHEAST COLORADO. TAFS HAVE BEEN ADJUSTED TO INDICATE THIS
TREND. THE EAST TO SOUTHEAST WINDS STILL EXPECTED TO CONTINUE
THROUGH MUCH OF THE AFTERNOON...BECOMING MORE SOUTHEAST 01Z...THEN
SOUTHERLY AROUND 06Z. COULD SEE SOME GUSTS TO 20 KTS AT KDEN AND
KAPA BETWEEN 22Z AND 06Z. A FEW THUNDERSTORMS COULD DEVELOP ALONG
THE FOOTHILLS AND PALMER DIVIDE WEST AND SOUTH OF THE DENVER AREA
BETWEEN 20Z AND 02Z. SHOULD NOT AFFECT THE AREA AIRPORTS...BUT
WILL INCLUDE A VCTS AT KBJC AND KAPA.

&&

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

$$

UPDATE...D-L
SHORT TERM...BAKER
LONG TERM...ENTREKIN
AVIATION...D-L