National Weather Service Forecast Discussion

000
FXUS65 KBOU 201010
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
410 AM MDT MON MAY 20 2013

.SHORT TERM...BAND OF SHOWERS WRAPPING AROUND THE NORTHERN PLAINS
LOW WILL COME ACROSS NORTHEASTERN COLORADO TODAY. THE ATMOSPHERE
IS A BIT COOLER WITH A LITTLE MORE MOISTURE THAN YESTERDAY...AND
THE NORTHWEST WINDS WILL ALSO BE STRONGER. THE FIRST BAND WILL
MOVE THROUGH DENVER AROUND SUNRISE WITH A BREAK BEHIND IT. ANOTHER
BAND LOOKS TIMED FOR LATE AFTERNOON OR EARLY EVENING...ALTHOUGH
THERE IS A GOOD CHANCE THAT ADDITIONAL CONVECTION WILL DEVELOP
WITH THE DIURNAL HEATING AS WELL. THERE SHOULD BE SOME DRYING
OVERNIGHT...BUT NOT ENOUGH TO PREVENT ALL SHOWER ACTIVITY. IN THE
MOUNTAINS THE SNOW LEVEL LOOKS TO BE BETWEEN 8 AND 9 THOUSAND FEET
AND THIS SHOULD RISE SLIGHTLY DURING THE DAY. BEST ACCUMULATION
MAY TURN OUT TO BE DUE TO THE SHOWER BANDS VERSUS OROGRAPHIC
EFFECTS...BUT IN ANY EVENT SEVERAL INCHES OF ACCUMULATION IN
HIGHER AREAS. IMPACT ON HIGHWAYS SHOULD BE LIMITED...BUT SOME
SLUSH IN THE SNOW BANDS DUE TO THE INTENSITY. OVERALL ONLY MINOR
CHANGES...MAINLY TO RAISE POPS AND MAKE SOME TIMING ADJUSTMENTS.

.LONG TERM...MODELS HAVE THE UPPER TROUGH AXIS OVER THE EASTERN
BORDER OF THE CWA AT 12Z TUESDAY MORNING. WEAK NORTH-
NORTHWESTERLY FLOW ALOFT IS PROGGED ON TUESDAY. AN UPPER RIDGE IS
PROGGED TO MOVE ACROSS COLORADO WEDNESDAY AND WEDNESDAY NIGHT
...WITH WEAK WESTERLY FLOW ALOFT. DOWNWARD SYNOPTIC SCALE ENERGY
IS EXPECTED FOR THE CWA TUESDAY THROUGH WEDNESDAY. UPWARD
VERTICAL VELOCITY IS PROGGED WEDNESDAY NIGHT. THE BOUNDARY LAYER
FLOW IS NORTHWESTERLY EARLY TUESDAY...THEN NORTHEASTERLY INTO
TUESDAY EVENING. SOUTHEASTERLY FLOW IS PROGGED THE REST OF THE
TUESDAY NIGHT CONTINUING THROUGH WEDNESDAY NIGHT. FOR MOISTURE...
IT IS LIMITED TUESDAY THROUGH WEDNESDAY EVENING. THERE IS SOME LOW
LEVEL MOISTURE TO ADVECT INTO THE PLAINS LATER WEDNESDAY NIGHT
WITH THE SOUTHEASTERLY LOW LEVEL FLOW. THERE IS A TINY BIT OF
CAPE PROGGED FOR THE WESTERN CWA LATE DAY TUESDAY. THERE IS
CONSIDERABLY MORE PROGGED OVER MUCH OF THE CWA LATE DAY WEDNESDAY.
THE BETTER AREAS...EASTERN MOUNTAINS...FOOTHILLS AND ADJACENT
PLAINS HAVE 500-1000 J/KG. AS FAR AS LAPSE RATES GO...THERE IS A
FAIR CAP IN PLACE FOR LATER DAY TUESDAY...LESS OF ONE LATE DAY
WEDNESDAY. THE QPF FIELDS SHOW A TAD OF MEASURABLE PRECIPITATION
OVER THE MOUNTAINS AND FOOTHILLS ON TUESDAY. TUESDAY NIGHT INTO
WEDNESDAY MORNING ARE DRY. THERE IS HIGHER AMOUNTS OF RAINFALL
PROGGED LATE DAY WEDNESDAY AND THAT IS OVER THE MOUNTAINS...
FOOTHILLS AND ADJACENT PLAINS. FOR POPS...WILL GO WITH 10-20%S FOR
THE MOUNTAINS AND FOOTHILLS LATE DAY TUESDAY...THEN 20-40%S FOR
ALL AREAS LATE DAY WEDNESDAY. FOR TEMPERATURES...TUESDAY`S HIGHS
ARE 2-4 C WARMER THAN MONDAY`S. WEDNESDAY`S HIGHS WARM UP ANOTHER
2-4 C FROM TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH
SUNDAY...MODELS KEEP A STRONG UPPER TROUGH/CLOSED LOW OVER THE
NORTHWESTERN UNITED STATES AND SOUTHWESTERLY FLOW ALOFT OVER THE
CWA ALL FOUR DAYS. MOISTURE IS FAIR AT BEST AND TEMPERATURES ARE
ABOVE SEASONAL NORMALS.

&&

.AVIATION...AN AREA OF RAIN SHOWERS WILL MOVE THROUGH DENVER
THIS MORNING. INSTRUMENT APPROACHES WILL BE NEEDED TO KDEN AND
THERE MAY BE SOME AREAS OF MVFR CEILINGS/VISIBILITIES. THERE
SHOULD BE A BREAK IN THE MIDDLE OF THE DAY AND CEILINGS MAY
IMPROVE...BUT SCATTERED SHOWERS ARE EXPECTED TO REDEVELOP WHICH
MAY LOWER CEILINGS AGAIN LATER IN THE AFTERNOON AND EVENING. NORTH
WINDS WILL GUST IN THE 20 TO 30 KNOT RANGE AT TIMES.

&&

.HYDROLOGY...RAIN SHOWERS ARE EXPECTED TO BE TOO LIGHT TO CAUSE A
FLOODING THREAT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR COZ031-
033.

&&

$$

SHORT TERM...GIMMESTAD
LONG TERM....RJK
AVIATION...GIMMESTAD

NWS BOU Office Area Forecast Discussion