458 
FXUS65 KBOU 190333
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
933 PM MDT MON MAR 18 2013

.UPDATE...


&&

.SHORT TERM...CLOUDS AND SNOW ARE LINGERING LONGER THEN EXPECTED
ALONG THE DIVIDE IN ZONES 33 AND 34 SO WILL TEND TO THAT IN THIS
UPDATE. WINDS RELAXING SIGNIFICANTLY OVER THE PLAINS.

.AVIATION...WINDS DECREASING AT DIA AT THIS TIME AND STILL THINK
THEY SHOULD GO TO NEAR NORMAL DRAINAGE DIRECTION SOONER RATHER
THAN LATER.      RJK

&&

.PREV DISCUSSION... /ISSUED 343 PM MDT MON MAR 18 2013/ 

SHORT TERM...WEB CAMS CONTINUE TO SHOW AREAS OF LIGHT SNOW ALONG
THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES...MAINLY WEST
AND NORTH FACING SLOPES. SOME SNOW ALSO OCCURRING OVER THE PARK
AND GORE RANGES OF WESTERN JACKSON COUNTY. THE SNOW HAS BEEN
SHOWING SOME SIGNS OF DECREASING. IN ADDITION...GUSTY WINDS WERE
OCCURRING ALONG THE FOOTHILLS AND ACROSS THE PLAINS WITH SOME
GUSTS AROUND 40 MPH. FOR TONIGHT...STRONG NORTHWEST FLOW ALOFT TO
CONTINUE. MODEL CROSS SECTIONS SHOW DRIER AIR MOVING INTO THE
MOUNTAINS THIS EVENING...SHOULD SEE SNOW CONTINUE TO DECREASE AND
COME TO AN END BY MIDNIGHT. MODELS CONTINUE TO INDICATE THE
DEVELOPMENT OF A STABLE LAYER NEAR MOUNTAIN TOP OVERNIGHT WHICH
WILL HELP WITH THE DEVELOPMENT OF A MOUNTAIN WAVE. THUS...WINDS TO
INCREASE IN AND NEAR FOOTHILLS AFTER MIDNIGHT. LATEST RAP CROSS
SECTIONS SHOWING CROSS MOUNTAIN FLOW INCREASING TO AROUND 50 KTS
AT MOUNTAIN TOP. SOME GUSTS AROUND 60 MPH A POSSIBILITY IN THE
WINDY LOCATIONS. ACROSS PLAINS...WINDS TO DECREASE DURING THE
EVENING ONCE THE AIRMASS STABILIZES. ON TUESDAY...A WEAKER
NORTHWEST FLOW ALOFT WILL BE OVER THE REGION. WINDS SHOULD
DECREASE THOUGH WILL BE A BIT GUSTY AT TIMES ACROSS THE RIDGES AND
ALONG THE FOOTHILLS. MIXING WILL ALSO ALLOW GUSTY WINDS TO OCCUR
NEAR THE WYOMING AND NEBRASKA BORDERS DURING THE AFTERNOON.
AIRMASS TO BE DRIER AND SLIGHTLY WARMER WITH ANY MOISTURE ABOVE
MOUNTAIN TOP. TEMPERATURES SHOULD WARM INTO THE 50S ACROSS THE
PLAINS. SOME AREAS MAY BE SLIGHTLY COOLER DUE TO LESS WIND.

LONG TERM...UPPER LEVEL RIDGE WILL BUILD EASTWARD ACROSS THE
CENTRAL ROCKIES TUESDAY NIGHT AND WEDNESDAY WITH DRY CONDITIONS.
HOWEVER...BY LATE WEDNESDAY...ENOUGH MOISTURE AND INSTABILITY
SHOULD BE ENOUGH TO PRODUCE SHOWERS IN THE MOUNTAINS. THE MAIN
SHOT OF Q-G LIFT AND MOISTURE INCREASE IS STILL SLATED TO HOLD OFF
UNTIL THURSDAY INTO THURSDAY EVENING. AT THIS TIME...THE
COMBINATION OF LIFT AND INSTABILITY SHOULD PRODUCE NUMEROUS
SHOWERS IN THE HIGH COUNTRY WITH LIGHT TO MODERATE SNOW
ACCUMULATIONS. ON THE PLAINS...RAIN SHOWERS ARE EXPECTED TO
DEVELOP BY THURSDAY AFTERNOON AND SPREAD EAST ACROSS THE PLAINS IN
THE EVENING WITH THE BEST LIFT. TEMPERATURES TURN COLD ENOUGH TO
HELP CHANGE RAIN SHOWERS OVER TO SNOW SHOWERS...BUT ANY
ACCUMULATION ON THE PLAINS MAY BE LIMITED OR NIL IF THE COLD AIR
LAGS SLIGHTLY BEHIND THE BETTER PRECIPITION AS CURRENTLY INDICATED
BY MOST MODEL RUNS.  

BY FRIDAY INTO SATURDAY...COLD AIR BECOMES MORE FIRMLY ENTRENCHED
ACROSS THE FORECAST AREA. MODELS HAVE SEEM TO COME AROUND TO A
FAIRLY UNIFORM SOLUTION BRINGING ANOTHER UPPER LEVEL DISTURBANCE
AROUND THE BASE OF THE TROUGH FOR FRIDAY NIGHT INTO SATURDAY.
HOWEVER...JUST 24 HOURS AGO WE WERE LOOKING AT A DRY FORECAST FOR
THAT TIME FRAME SO CONFIDENCE ON ANY TIMING HAS TO BE QUITE LOW.
ANOTHER DISTURBANCE IS LIKELY LATE IN THE WEEKEND OR EARLY NEXT
WEEK. THE MAIN POINT OF THIS FORECAST WILL BE TO HAVE AN EXTENDED
PERIOD OF COOLER AND UNSETTLED WEATHER. THERE WILL BE A THREAT OF
ACCUMULATING SNOWFALL WITH ANY OF THE DISTURBANCES THAT MOVE
THROUGH.

AVIATION...WINDS HAVE BEEN MORE WESTERLY AT KDEN AND KBJC WITH
NORTHWESTERLY AT KAPA. LATEST RAP AND HRRR CONTINUE TO INDICATE
NORTHWEST WINDS ACROSS THE AREA AIRPORTS THROUGH 01Z...STILL
EXPECTING WINDS TO BECOME A BIT MORE NORTHWEST AS MIXING
CONTINUES WITH SOME GUSTS AROUND 35 KTS. WINDS TO WEAKEN AFTER 01Z
AND BECOMING SOUTHERLY BY 03Z AS DRAINAGE PATTERN DEVELOPS. WINDS
TO BE MORE WESTERLY AT BJC DUE TO THE LOCAL DOWNSLOPE WITH
OCCASIONAL GUSTS TO 30 KTS POSSIBLE. ON TUESDAY...WINDS TO SHIFT
TO THE NORTHWEST BY 15Z WITH SPEEDS LESS THAN 10 KTS. WINDS COULD
BECOME NORTHEAST OR EAST AT DEN DURING THE AFTERNOON AS MODELS
SHOW WEAK SURFACE HIGH DEVELOPING IN THE DENVER AREA. VFR TO
CONTINUE.

&&

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

$$

SHORT TERM...BARJENBRUCH
LONG TERM....D-L
AVIATION...BARJENBRUCH