Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 250334
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
834 PM MST MON NOV 24 2014

.UPDATE...
ISSUED AT 830 PM MST MON NOV 24 2014

MAIN CHANGE TO EVENING FORECAST WAS TO DELAY THE HIGH WIND WARNING
A BIT UNTIL 10Z(3 AM). CROSS SECTIONS AND FORECAST SOUNDINGS DON`T
SHOW THESE STRONGER WINDS DEVELOPING UNTIL LATER TNT WHEN THE
STRONGER WARMING AND MOUNTAIN TOP INVERSION BEGINS TO STRENGTHEN.
HIGH WINDS WILL FIRST DEVELOP IN THE FOOTHILLS LATER TONIGHT AND
THEN SPREAD TO THE BASE OF THE FOOTHILLS AFTER DAYBREAK. APPEARS
THE STRONGEST WINDS CAN BE EXPECTED BETWEEN 15Z-00Z DURING THE
DAY ON TUESDAY AS JET CORE SHIFTS EAST OF THE MOUNTAINS ALONG WITH
INCREASING SURFACE GRADIENT WHICH PEAKS AT AROUND 15MB FROM GJT-
DEN. AS A COUNTER NOTE TO THE HIGH WINDS...AS DEEPER MOISTURE
MOVES INTO THE MOUNTAINS AGAIN LATER TUESDAY MORNING IT COULD
START TO DEAMPLIFY THE WAVE AND RESULTING IN WEAKER WINDS. JUST
SOMETHING TO WATCH AS WE GO INTO THIS EVENT.

THE OTHER FEATURE IS THE BANDED PRECIP WHICH IS BEING FORECAST BY
SOME OF THE MODELS TUESDAY NIGHT ACROSS THE PLAINS. PRECIP IS
ORIENTED WITH THE JET SO AT SOME POINT MAY NEED HIGHER POPS ON THE
PLAINS AND QUESTION WILL BE HOW FAR WEST WILL THE BANDS MAKE IT?
MORE QUESTIONS FOR LATER SHIFTS.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 320 PM MST MON NOV 24 2014

BEST LIFT WITH TODAYS SHORTWAVE IS MOVING OUT OF THE MOUNTAINS AND
ACROSS THE PLAINS AT THIS TIME. THERE WOUND UP BEING A NICE LITTLE
LOW LEVEL FRONT WITH THIS WAVE WITH A QUICK BIT OF WIND AND
COOLING ALONG WITH THE SHOWERS. SKIES ALREADY STARTING TO CLEAR
WEST OF THE FRONT RANGE AND ALONG THE NORTHERN BORDER...AND THE
SHOWERS SHOULD MAKE THEIR WAY OUT OF OUR AREA ON SCHEDULE THIS
EVENING. IT LOOKS LIKE THERE WILL BE A FAIRLY GOOD BREAK WITH
CLEARING TONIGHT...THOUGH THERE WILL STILL BE SOME SHALLOW
CONVECTION UPSTREAM OF THE FRONT RANGE.

THERE WILL BE STRONG WARM ADVECTION ALOFT OVERNIGHT AS THE 130
KNOT JET CORE MOVES OVER US. NEARLY IDEAL PROFILE FOR AN AMPLIFIED
MOUNTAIN WAVE BY TUESDAY MORNING WITH THE STRONG
INVERSION...STRONG NORTHERLY JET...AND NORTHWEST WINDS AROUND 50
KNOTS JUST ABOVE THE MOUNTAINS. DURING THE DAY THE INVERSION WILL
LOWER AND WEAKEN...THE FLOW ALOFT WILL BECOME MORE NW AND
WEAKEN...WHILE THE FLOW AT MOUNTAINTOP WILL INCREASE A BIT MORE.
THIS SHOULD LEAD TO MORE OF A JUMP THAN A STANDING WAVE BY LATE IN
THE DAY...SO BETTER CHANCE OF GETTING EAST OF THE FOOTHILLS BUT
LESS AMPLIFICATION. WITH NO COLD AIR ON THE PLAINS AND A GREAT
AMPLIFICATION PROFILE...AND THEN THE MORE MIXED WAVE LATER
ON...INCLUDING THE NEAR FOOTHILLS ZONES LOOKS LIKE A GOOD CALL.
WOULD NOT BE SURPRISED TO SEE 100 MPH WINDS SOMEWHERE ON
TUESDAY...MOST LIKELY THE HIGHER WIND PRONE AREAS BUT NOT OUT OF
THE QUESTION FOR THE LOWER BOULDER FOOTHILLS DURING THE BEST WAVE
TUESDAY MORNING. I WILL GO WITH A WARNING AND EXTEND THE VALID
TIME TO START AT MIDNIGHT TONIGHT AND GO THROUGH TUESDAY NIGHT.
LOWER THREAT OF HIGH WINDS TUESDAY NIGHT BUT IT WILL BE PLENTY
WINDY AND MORE WIDESPREAD.

FINALLY...MOISTURE WILL COME BACK IN DURING THE DAY TUESDAY.
INITIALLY THE LOW LEVELS ARE UNDER THE INVERSION...BUT THERE WILL
BE A PERIOD WITH SOME HIGHER LEVEL MOISTURE FROM THE WARM
ADVECTION...ENOUGH TO MAKE SOME LIGHT SNOW FROM ABOVE. IN ADDITION
WITH THE STRONG WINDS THE RISING PART OF THE MOUNTAIN WAVE COULD
BE A SIGNIFICANT SNOW PRODUCER. AND PLENTY OF WIND TO BLOW AROUND
WHATEVER IS THERE...SO WE WILL HAVE A WINTER WEATHER ADVISORY
STARTING AT 11 AM AND GOING THROUGH TUESDAY NIGHT.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 320 PM MST MON NOV 24 2014

A STRONG NORTHWESTERLY FLOW ALOFT WILL REMAIN IN PLACE OVER
COLORADO TUESDAY NIGHT AND WEDNESDAY. SUFFICIENT MOISTURE COUPLED
WITH STRONG OROGRAPHIC COMPONENT TO ALLOW FOR ADDITIONAL  SNOWFALL
TUESDAY NIGHT. THE COMBINATION OF SNOW/BLOWING SNOW ENOUGH TO
CONTINUE THE WINTER WEATHER ADVISORY THROUGH 12Z WEDNESDAY
MORNING. ACROSS THE NORTHEAST PLAINS...MDLS CONTINUE TO BRING SNOW
SHOWERS INTO THE NORTHEAST PLAINS OVERNIGHT. STRONG DOWNSLOPE NEAR
THE FOOTHILLS SHOULD NEGATE MOST OF THE SHOWER ACTIVITY IN THE
URBAN CORRIDOR FROM AROUND LONGMONT SOUTHWARD. NORTH AND EAST WL
GO WITH SCT POPS THROUGH TUESDAY EVENING. NOT BIG CHANGES IN THE
GRIDS FOR WEDNESDAY THROUGH SATURDAY. THE UPPER RIDGE AXIS WILL
SHIFT EASTWARD AND THE RIDGE WILL DEAMPLIFY ALLOWING THE FLOW
ALOFT TO BE MORE ZONAL. AS A RESULT...IT WILL BE DRY AND WARMER
THROUGH THE PERIOD. THE STORM TRACK WILL SHIFT TO THE NORTH WITH
PLENTY OF PACIFIC MOISTURE MOVING ACROSS THE NORTHERN ROCKIES AND
INTO THE DAKOTAS. A COLD FRONT IS PROGGED TO SLIP INTO NORTHEAST
COLORADO SATURDAY NIGHT...ALLOWING FOR COOLER TEMPERATURES ON
SUNDAY. OVERALL HOWEVER...IT SHOULD REMAIN DRY THROUGH MONDAY.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z TUESDAY EVENING)
ISSUED AT 808 PM MST MON NOV 24 2014

SURFACE WINDS STILL NORTHWEST AT KDEN BUT EXPECTED TO SHIFT WEST
AND SOUTHWEST OVERNIGHT. WINDS AT APA/BJC HAVE ALREADY DIMINISHED
TO A LIGHT WESTERLY. WINDS WILL FIRST INCREASE AGAIN AT BJC
TOWARDS 12Z WITH PEAK WINDS EXPECTED BETWEEN 15-22Z. WINDS WILL
INCREASE AT APA/DEN AS WELL...BUT A BIT LATER AS WAITING FOR LOW
LEVELS TO MIX OUT A BIT WHILE SURFACE GRADIENT INTENSIFIES AND
PEAKS AROUND 18Z. PEAK WINDS AT KDEN BY MIDDAY TUESDAY LIKELY
AROUND 30KT...APA...20KT AND BJC CLOSE TO 50KT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 3 AM TUESDAY TO 5 AM MST WEDNESDAY FOR
COZ035-036-038-039.

WINTER WEATHER ADVISORY FROM 11 AM TUESDAY TO 5 AM MST WEDNESDAY
FOR COZ031-033-034.

&&

$$

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



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