Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 301658
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1058 AM MDT TUE SEP 30 2014

.UPDATE...
ISSUED AT 1057 AM MDT TUE SEP 30 2014

FORECAST ON TRACK WITH GUSTY WINDS IN/NEAR THE FRONT RANGE
MOUNTAINS AND FOOTHILLS...AS WELL AS THE NORTHERN BORDER AREA. THE
STRONGEST WINDS WILL BE CONFINED TO THOSE AREAS THROUGH THE
AFTERNOON. GUSTS TO 50 MPH EXPECTED ABOVE TIMBERLINE WITH 30 TO 40
MPH GUSTS NEAR THE WYOMING BORDER. HOWEVER...THEY WILL GRADUALLY
WEAKEN THROUGH THE COURSE OF THE AFTERNOON AS CROSS MOUNTAIN
COMPONENT EASES. MEANWHILE...WITH INCREASED MIXING WE DO EXPECT
CHANNELS OF WESTERLY WINDS TO SPREAD ONTO THE PLAINS. AT THE SAME
TIME SOME LOCATIONS COULD REMAIN EASTERLY IN THIS CURRENT WEATHER
SCENARIO SINCE STRONGEST DOWNWARD FORCING IS PUSHING EAST OF THE
FORECAST AREA.

MAIN CHANGE WAS TO ADD SOME LOW POPS ON THE PLAINS BY THIS EVENING
AS LATEST MODEL RUNS ARE SHOWING A BIT OF CAPE AND ENOUGH HEATING
TODAY TO SUFFICIENTLY MIX OUT STABLE LAYER. IN ADDITION...THE WEAK
WAVE MOVING ACROSS UTAH MAY PROVIDE SUFFICIENT COOLING TO ALLOW A
FEW SHOWERS TO SPREAD ONTO THE PLAINS. ALSO BUMPED UP POPS IN THE
MOUNTAINS FOR OROGRAPHICS COMBINING WITH WEAK LIFT THROUGH
TONIGHT.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 400 AM MDT TUE SEP 30 2014

DEEP UPPER AIR CYCLONE CENTERED OVER EXTREME NWRN NEBRASKA AT
THIS HOUR WILL CONTINUE TO QUICKLY TRACK NORTH-NORTHEASTWARD ACRS
NORTH DAKOTA THIS MORNING AND THEN UP OVER MANITOBA LATER TODAY.
STRONG MID-LEVEL SUBSIDENCE ON THE BACK SIDE OF THIS DEPARTING LOW
PRES SYSTEM WAS NOW OVER COLORADO. NAM AND RAP QG VERT VELOCITY
FIELDS AND ON H2O VAPOR SAT IMAGERY NICELY REVEAL THIS SINKING.
STABILIZATION OF THE MTN TOP LAYER PAST FEW HOURS HAS PRODUCE A
STANDING MTN WAVE ALONG THE FRONT RANGE...RESULTING IN GUSTY
WEST-NORTHWEST WINDS AT HIGHER ELEVATIONS OF THE FRONT RANGE. NAM
AND RAP CROSS SECTIONS INDICATE CROSS BARRIER WINDS IN THE
45-55KT RANGE BY AROUND 12Z THIS MORNING...THEN ONLY SLIGHTLY
WEAKER AT 15Z. WIND SENSORS ATOP THE HIGH RIDGES WERE ALREADY
INDICATING GUSTS IN THE 45-55 MPH RANGE. COULD SEE SOME OF THIS
MOMENTUM SPREADING TO LOWER EAST SLOPES OF THE FRONT RANGE DURING
THE NEXT FEW HOURS. DO NOT SEE WINDS REACHING HIGH WIND CRITERIA
AT THIS TIME. FURTHERMORE...DO NOT ANTICIPATE THESE STRONG WINDS
WILL SPREAD OUT ONTO THE NEARBY THE PLAINS. ALTHOUGH THE
NORTHEAST CORNER OF THE CWA COULD SEE W-NWLY WIND GUSTS TO 40 MPH
LATE THIS MORNING AND EARLY THIS EVENING WITH MOMENTUM MIXING DOWN
FROM ALOFT.

CLEARING EARLY THIS MORNING WILL GIVE WAY TO INCREASING MID AND
HIGH CLOUDS EAST OF THE MTNS LATER TODAY. CLOUDY SKIES WILL ALSO
RETURN TO AREAS ALONG AND WEST OF THE CONTINENTAL DIVIDE WITH A
WEATHER DISTURBANCE RACING IN FROM THE NORTHWEST. QG VV REVERSE
AND GO POSITIVE THIS AFTERNOON AS THIS NEXT WAVE OF MOISTURE AND
ENERGY NEARS. COULD SEE SCATTERED SHOWERS AND ISOLATED T-STORMS
IN THE MTNS AND HIGH VALLEYS BY MID- TO LATE AFTERNOON. SNOW LEVEL
WILL HOOVER AROUND 11 THSND FT TODAY...AND DROP TO AROUND 9500 FT
THIS EVENING. HOWEVER ANY SNOW ACCUMULATION SHOULD BE MINIMAL.
BY EVENING SKIES SHOULD ALSO FILL WITH CLOUDS EAST OF THE MTNS AS
THIS WEAK PERTABATION PASSES BY...THEN PARTIAL CLEARING LATE
WITH ITS DEPARTURE. PCPN IS NOT ANTICIPATED THRU 12Z/WED EAST OF
THE MTNS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 400 AM MDT TUE SEP 30 2014

THE NEXT UPPER LEVEL TROF WILL MOVE ACROSS COLORADO ON WEDNESDAY
AFTERNOON AND NIGHT. AN ASSOCIATED COLD FRONT WILL MOVE ACROSS
NORTHEAST COLORADO DURING THE AFTERNOON HOURS WITH INCREASING
NORTHERLY FLOW AT LOW LEVELS. QG FIELDS SHOWING INCREASING ASCENT
DURING THE DAY WEDNESDAY...PEAKING OVER THE FRONT RANGE IN THE
AFTERNOON AND FURTHER EAST ON THE PLAINS DURING THE EARLY EVENING.
SHORT RANGE MODELS ARE FAIRLY CONSISTENT ON TIMING WITH THIS TROF. GIVEN
THE FRONT AND FORCING ALOFT WILL BUMP POPS UP FURTHER TO LIKELY
OVER MOST SECTIONS DURING WEDNESDAY AFTERNOON AND EVENING. THE
TROF IS QUITE PROGRESSIVE SO SHOWERS WILL END FROM NORTHWEST TO
SOUTHEAST WEDNESDAY NIGHT AS PRECIP DURATION WILL BE IN THE 3-6
HOUR RANGE. THE AIRMASS WILL BE COLD ENOUGH TO SUPPORT SOME SNOW
ACCUMULATION IN THE MOUNTAINS.

FOR THURSDAY AND BEYOND...THERE WILL BE A DRYING AND WARMING TREND
AS COLORADO WILL BE UNDER A MODERATE...NORTHWEST FLOW PATTERN.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 1057 AM MDT TUE SEP 30 2014

WIND DIRECTION FORECAST WILL BE A CHALLENGE THROUGH THE AFTERNOON
WITH POTENTIAL FOR CHANNELS OF WESTERLY WINDS TO MOVE OFF THE
FOOTHILLS. AT THE SAME TIME...THERE WILL BE SOME DIURNAL
EASTERLIES THAT THE WESTERLY WINDS WILL BE BATTLING THROUGH 00Z.
WEST WINDS COULD GUST TO AROUND 18 KTS WHILE ANY EASTERLIES WILL
BE LIGHTER AROUND 5-10 KTS. AFTER 00Z...WINDS ARE EXPECTED TO
TRANSITION TO NORMAL DIURNAL SOUTH/SOUTHEWESTERLIES NEAR 10 KTS.
LOW CHANCE OF A LIGHT RAIN SHOWER 00Z-05Z BUT CEILINGS WILL REMAIN
HIGH ENOUGH FOR VISUAL LANDING CONDITIONS.

&&

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

$$

UPDATE...BARJENBRUCH
SHORT TERM...BAKER
LONG TERM...ENTREKIN
AVIATION...BARJENBRUCH



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