Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 231549
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
949 AM MDT TUE SEP 23 2014

.UPDATE...
ISSUED AT 927 AM MDT TUE SEP 23 2014

QUITE A BIT OF MID LEVEL MOISTURE OVER NORTHERN COLORADO WITH
TRAPPED MOUNTAIN WAVES. 12Z SOUNDING AT DENVER HAD STRONG
INVERSION AT 500MB WHICH WILL GRADUALLY WEAKEN WITH TIME. THERE
ARE STILL A FEW SHOWERS OVER NORTHERN MOUNTAINS AND FOOTHILLS BUT
SHOWERS ARE VERY LIGHT. WITH THE MOUNTAIN WAVE...STILL SOME GUSTY
WINDS OVER THE MOUNTAIN PASSES UP TO 45KT. ONLY VERY MARGINAL
INSTABILITY THIS AFTERNOON WITH ANY SFC BASED CAPES UNDER 500J/KG.
EVEN THUNDER MAY BE A STRETCH TODAY. WILL KEEP ANY SHOWERS MAINLY
CONFINED TO MOUNTAINS AND HIGHER TERRAIN AREAS AND OVER FAR NE
PLAINS.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 357 AM MDT TUE SEP 23 2014

SHALLOW MOIST LAYER CONTINUES TO STREAM ACROSS NORTHERN COLORADO
IN WESTERLY FLOW. THERE WILL BE SOME DRYING...INCREASED
SUBSIDENCE AND WARMING ALOFT TODAY BUT THIS WILL BE PRETTY
GRADUAL...SO THE CLEARING MAY BE SLOW. THERE MAY BE SOME
CONVECTIVE REDEVELOPMENT OF THIS LAYER IN THE AFTERNOON AS WELL.
BIGGEST CHANGE TODAY WAS TO INCREASE CLOUD COVER. GIVEN SLIGHT
DRYING AT THE SURFACE AND WARMING ALOFT INCLUDING THE DEVELOPMENT
OF A STABLE LAYER AROUND 500-600 MB I BACKED OFF A BIT MORE ON
THUNDERSTORM COVERAGE...LIMITING LOW POPS TO THE NORTHEAST CORNER
AND THE MOUNTAINS. IN THE MOUNTAINS STRONG WINDS APPEAR LIMITED TO
THE WINDIEST PLACES...WE HAVE HAD GUSTS TO 50 MPH ON MINES PEAK AT
13500 FEET...BUT NOT MUCH ANYWHERE ELSE. FLOW ALOFT WILL BE
DECREASING A BIT DURING THE DAY SO NOT EXPECTING THIS TO SPREAD
MUCH....MAYBE A LITTLE BREEZE DOWN INTO THE VALLEYS FROM MIXING
THIS AFTERNOON. HIGH TEMPERATURES STILL LOOK GOOD...I DROPPED
TONIGHTS LOWS A LITTLE BELOW GUIDANCE WITH GOOD CLEARING EXPECTED
AND LIGHT WINDS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM MDT TUE SEP 23 2014

A RIDGE OF HIGH PRESSURE WILL STRETCH FROM THE DESERT
SOUTHWEST...ACROSS COLORADO AND INTO THE NORTHERN GREAT PLAINS
THROUGH FRIDAY. AS A RESULT A DRY AND SUBSIDENT AIRMASS WILL BRING
ABOVE NORMAL TEMPERATURES BACK INTO THE CWFA. THE RIDGE AXIS WILL
SHIFT TO THE EAST BY THE WEEKEND...ALLOWING FOR A SOUTHWESTERLY
FLOW OVER COLORADO. SUBTROPICAL MOISTURE WILL BECOME ENTRAINED
INTO THE FLOW AND ADVECT INTO COLORADO. AS A RESULT...A CHANCE OF
SHOWERS AND THUNDERSTORMS WILL RETURN TO THE CWA. INITIALLY THE
FLOW ALOFT WILL BE FAIRLY WEAK...WITH INCREASING PRECIPITABLE
WATER VALUES. THE GFS FORECAST SOUNDINGS GENERATE PW VALUES AROUND
0.80 INCHES SATURDAY AFTN...TO 0.90 INCHES SUNDAY AFTN.  THE FLOW
ALOFT WILL INCREASE SUNDAY INTO MONDAY...AS THE NEXT UPPER TROUGH
MOVES INTO THE GREAT BASIN. THE STRONGER FLOW ALOFT SHOULD HELP
OFFSET THE HEAVY RAIN THREAT TO SOME DEGREE. TEMPERATURES WILL BE
COOLER AS WELL. THERE IS SOME DISAGREEMENT REGARDING THE STRENGTH
AND TRACK OF THE NEXT SYSTEM. THE GFS IN THE DEEPEST WHILE THE
ECMWF KEEPS THE SYSTEM FURTHER TO THE NORTH AND WEST. THE CANADIAN
MODELS IN MORE OF A TWEENER. WILL NOT CHANGE MUCH TO WHAT IS
ALREADY IN THE GRIDS. THE BEST CHANCE OF STORMS WILL BE OVER THE
HIGH COUNTRY...WITH A LESSER CHANCE OVER THE NORTHEAST PLAINS.
SUNDAY WOULD APPEAR TO BE THE WETTEST DAY OF THE EXTENDED
PERIOD...AT LEAST FOR NOW.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 927 AM MDT TUE SEP 23 2014

HINTS OF THE MID LEVEL DECK OF CLOUDS BEGINNING TO DISSIPATE JUST
A BIT SO SHOULD SEE CLOUDS BECOMING MORE SCATTERED TOWARDS 18Z.
NOT ENOUGH INSTABILITY FOR STORMS TODAY SO WILL LEAVE TERMINALS
DRY WITH GRADUAL CLEARING TONIGHT. SOUTHERLY WINDS WILL GRADUALLY
SHIFT NORTHWEST AS LOW LEVELS MIX OUT THIS AFTERNOON...GENERALLY
UNDER 15KT.

&&

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

$$

UPDATE...ENTREKIN
SHORT TERM...GIMMESTAD
LONG TERM...COOPER
AVIATION...ENTREKIN



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