High Wind in Colorado, March 24, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
400 AM MDT TUE MAR 24 2009

.SHORT TERM...WARM ADVECTION WRAPPING BACK AROUND THE SOUTH DAKOTA
LOW WITH LIGHT SNOW SPREADING BACK INTO NORTHEASTERN COLORADO EARLY
THIS MORNING. THE SNOW IS FIGHTING SOME PRETTY FIERCE DOWNSLOPE OFF
THE FOOTHILLS AND CHEYENNE RIDGE HOWEVER...AS WELL AS GRADUAL
ENTRAINMENT OF DRIER AIR. SO SNOW RATES WILL REMAIN QUITE LIGHT. IN
ADDITION...WARM GROUND WILL LIMIT ANY ACCUMULATION. MAIN BAND OF
LIFT APPEARS TO ALREADY BE PASSING OVER OUR AREA WITH A NICE DRY
SLOT ON THE SOUTH SIDE OF THE CHEYENNE RIDGE...AND LIFT SHOULD
DECREASE THIS MORNING. HOWEVER...THE WIND WILL CONTINUE AS THE TIGHT
MIDLEVEL HEIGHT GRADIENT PASSES BY DURING THE DAY. WE HAVE ALREADY
BEEN GETTING GUSTS TO AROUND 60 MPH IN BETWEEN SNOW BANDS ON THE
PLAINS...MODELS SHOW THE LOW LEVEL WINDS PEAKING THIS MORNING BUT
MIXING WILL BE DEEPER THIS AFTERNOON...WILL LET THE CURRENT WARNING
RUN ALL DAY. ONE OTHER CHANGE WAS TO INCREASE POPS IN THE MOUNTAINS
THROUGH TONIGHT. THERE APPEARS TO BE ENOUGH MOISTURE TO KEEP SOME
HIGH POPS WITH LOW AMOUNTS...MOISTURE NEVER REALLY GOES AWAY BEFORE
WEAK LIFT COMES BACK IN FROM THE WEST LATE TONIGHT.

.LONG TERM...MODELS GOT IN LINE BETTER WITH ONE ANOTHER CONCERNING
WEDNESDAYS WEAK UPPER TROUGH.  IT MOVES ACROSS THROUGH ALL THE
FORECAST AREA BY 00Z LATE WEDNESDAY AFTERNOON.  FAIRLY STRONG
NORTHWESTERLY FLOW ALOFT WEDNESDAY EVENING WEAKENS AND BECOMES ZONAL
BY 12Z THURSDAY MORNING...THEN SOUTHWESTERLY BY THURSDAY AFTERNOON
AS THE NEXT UPPER TROUGH DEVELOPS NORTH AND NORTHWEST OF COLORADO.
BY THURSDAY AFTERNOON...ALL THREE MODELS SHOW THE UPPER CIRCULATION
AROUND THE FOUR CORNERS AREA.  AT 12Z FRIDAY MORNING...THE ECMWF HAS
IT OVER THE TEXAS PANHANDLE...THE NAM OVER NORTH CENTRAL NEW MEXICO
AND THE GFS IN BETWEEN THE TWO.  THE GFS BARELY HAS A CLOSED
CIRCULATION AT THIS TIME.  THE QG VERTICAL VELOCITY FIELDS HAVE WEAK
UPWARD MOTION FOR THE FORECAST AREA FOR THE FIRST HALF OF
WEDNESDAY...THEN A BRIEF SHOT OF DOWNWARD MOTION INTO THE EARLY
EVENING.  BY MID EVENING WEDNESDAY NIGHT...UPWARD MOTION IS ON THE
INCREASE WITH THE NEXT STORM.  THE UPWARD MOTION CONTINUES THROUGH
ALL OF THURSDAY NIGHT.  THE STRONGEST VERTICAL VELOCITY STAYS JUST
WEST...AND THEN JUST SOUTH OF THE FORECAST AREA WITH THIS SYSTEM.
THE LOW LEVEL PRESSURE AND WIND FIELDS HAVE WEAK TROUGHING EAST OF
THE MOUNTAINS WEDNESDAY AND WEDNESDAY EVENING.  BY WEDNESDAY
NIGHT...THE MODELS DIFFER ON THE LOCATION OF SURFACE FEATURES.  THE
COLD AND UPSLOPE SURGE GET IN HERE BY 12Z THURSDAY MORNING ON THE
GFS...BUT ON THE NAM...ITS NOT UNTIL 18Z-21Z THURSDAY AFTERNOON.
BY 00Z THURSDAY AFTERNOON...BOTH MODELS HAVE PRETTY DEEP
UPSLOPE...ABOVE 600 MB ANYWAY.  THE NAM KEEPS THAT GOING THROUGH AT
LEAST 12Z FRIDAY MORNING...THE GFS STARTS DOWNSLOPING AND DRYING
THINGS OUT BY 06Z-12Z LATE THURSDAY NIGHT.  FOR MOISTURE...THE
MOUNTAINS ARE DEEPLY SATURATED FROM WEDNESDAY MORNING THROUGH MUCH
OF THURSDAY NIGHT.  THE GFS STARTS DRYING THEM OUT AFTER 06Z
THURSDAY NIGHT...THE NAM DOES NOT.  OVER THE PLAINS...THERE IS
PLENTY OF MOISTURE IN THE MID AND UPPER LEVELS ON BOTH MODELS
WEDNESDAY.  THE WESTERN PLAINS HAVE MORE DRYING IN THE LOWER AND MID
LEVELS... COMPARED TO THE EASTERN PLAINS.  THE PLAINS STAY FAIRLY
DRY WEDNESDAY NIGHT ON THE NAM...BUT HAVE DEEP MOISTURE IN PLACE
AFTER 06Z ON THE GFS.  THE GFS HAS DEEP MOISTURE OVER THE PLAINS ALL
DAY THURSDAY...THE NAM DOESNT SHOW THIS UNTIL WELL INTO THURSDAY
AFTERNOON.  THE NAM KEEPS ALL THE PLAINS IN DEEP MOISTURE ALL
THURSDAY NIGHT...THE GFS STARTS SIGNIFICANT DRYING BY 06Z THURSDAY
NIGHT.  THE QPF FIELDS KEEP MEASURABLE SNOW GOING IN THE MOUNTAINS
WEDNESDAY THROUGH THURSDAY NIGHT.  OVER THE PLAINS...PRECIPITATION
IS NOTED FROM LATE WEDNESDAY NIGHT INTO EARLY FRIDAY MORNING.  THE
NAM HAS CONSIDERABLY MORE THAN THE GFS.  THE LOOK OF THE JET MAXIMUM
ON THE BACK SIDE OF TROUGH MAKES ME WONDER IF THE CIRCULATION MIGHT
END UP FURTHER SOUTH ON FUTURE RUNS?  ALTHOUGH THE LAST FEW RUNS
HAVE KEPT THE CENTER PRETTY MUCH CONSISTENT CONCERNING LOCATION AND
TIMING.  ALSO...THE ANTI-CYCLONIC UPSLOPE IS A GOOD BET...EVEN IF
THE UPPER SYSTEM ENDS UP TO BE AN OPEN WAVE WITH ITS BOTTOM EVEN
FURTHER SOUTH THEN WHAT IT SHOWS NOW.  MOST OF THE FORECAST AREA
SHOULD SEE SOME MEASURABLE SNOW NO MATTER HOW THE VARIOUS PARAMETERS
CONTINUE TO DIFFER.  WILL EDGE POPS UP A BIT OVER THE PLAINS...WITH
MOST ZONES HAVING LIKELY POPS.  TIMING ISSUES PRECLUDE ANY
HIGHLIGHTS RIGHT NOW.  IN THE MOUNTAINS...WILL GO LIKELY POPS ON
WEDNESDAY WITH THE MOISTURE...LAPSE RATES...ARE OROGRAPHICS HELP IN
MIND.  BY WEDNESDAY NIGHT...THE UPPER TROUGH/CLOSED LOWS INFLUENCE
WILL KEEP POPS LIKELY AND THAT SHOULD CONTINUE THROUGH THURSDAY
NIGHT.  FOR TEMPERATURES...WEDNESDAYS HIGHS ARE CLOSE TO...OR
SLIGHT SLIGHTLY COOLER THAN TODAYS HIGHS.  ON THURSDAY...THE NAM
BRINGS THE FRONT DOWN IN THE AFTERNOON...THE GFS HAS IT THROUGH BY
MORNING.  WILL COOL OFF HIGHS FROM WEDNESDAYS AND GO SOMEWHERE IN
BETWEEN THE TWO MODELS.  FOR THE LATER DAYS...FRIDAY THROUGH
MONDAY...THE GFS AND ECMWF PUSH THE UPPER TROUGH/CLOSED LOW EAST.
THE DGEX KEEPS IT OVER NEW MEXICO INTO SATURDAY.  BY SATURDAY...
UPPER RIDGING TAKES OVER...ZONAL FLOW SATURDAY NIGHT INTO SUNDAY...
THEN A BROAD UPPER TROUGH ON THE GFS INTO MONDAY.  THERE IS A CLOSED
LOW MOVING ACROSS COLORADO ON THE ECMWF FOR THIS SAME TIME FRAME.
THE TYPICAL DAY 6 THROUGH 8 MESS.   WILL LEAVE SOME MINIMAL POPS IN
THE HIGH MOUNTAINS THROUGH MUCH OF THE PERIOD.  DRY ON THE PLAINS
FOR NOW.  TEMPERATURES GETTING AT OR SLIGHTLY ABOVE NORMALS ON
SATURDAY AND SUNDAY.

&&

.AVIATION...SNOW SHOWERS IN THE DENVER AREA SHOULD END BY 13Z...WITH
VFR CONDITIONS AFTER THAT AND CEILINGS GENERALLY ABOVE 6000 FT.
NORTHWEST WINDS WILL INCREASE TODAY WITH GUSTS IN THE 30 TO 40 KNOT
RANGE BY MIDDAY. WINDS WILL DECREASE AND BECOME SOUTHERLY BY MID
EVENING.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...HIGH WIND WARNING UNTIL 6 PM
      NORTHEAST PLAINS...ZONES 42..44..48>51.

GIMMESTAD/RJK

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE DENVER CO
1121 AM MDT MON MAR 23 2009

COZ030>051-241200-
JACKSON COUNTY BELOW 9000 FEET-WEST JACKSON AND WEST GRAND
COUNTIES ABOVE 9000 FEET-GRAND AND SUMMIT COUNTIES BELOW 9000
FEET-SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/
NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET-SOUTH AND SOUTHEAST
GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/GILPIN/CLEAR CREEK/
SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE 9000 FEET-LARIMER AND
BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-JEFFERSON AND WEST
DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR CREEK/NORTHEAST PARK
COUNTIES BELOW 9000 FEET-CENTRAL AND SOUTHEAST PARK COUNTY-LARIMER
COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY-BOULDER AND JEFFERSON
COUNTIES BELOW 6000 FEET/WEST BROOMFIELD COUNTY-NORTH DOUGLAS
COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND ARAPAHOE COUNTIES/
EAST BROOMFIELD COUNTY-ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES
ABOVE 6000 FEET-NORTHEAST WELD COUNTY-CENTRAL AND SOUTH WELD
COUNTY-MORGAN COUNTY-CENTRAL AND EAST ADAMS AND ARAPAHOE COUNTIES-
NORTH AND NORTHEAST ELBERT COUNTY BELOW 6000 FEET/NORTH LINCOLN
COUNTY-SOUTHEAST ELBERT COUNTY BELOW 6000 FEET/SOUTH LINCOLN
COUNTY-LOGAN COUNTY-WASHINGTON COUNTY-SEDGWICK COUNTY-PHILLIPS
COUNTY-
1121 AM MDT MON MAR 23 2009

...WINTER STORM WARNING NORTH CENTRAL MOUNTAINS MIDNIGHT TODAY
THROUGH 6 AM TUESDAY...
...WINTER WEATHER ADVISORY FOR LOWER ELEVATIONS OF GRAND AND JACKSON
COUNTIES FOR SNOW AND BLOWING SNOW TODAY THROUGH 6 AM
TUESDAY...
...WINTER WEATHER ADVISORY FOR THE NORTHERN FRONT RANGE FOOTHILLS
TODAY THRU MIDNIGHT TONIGHT.
...WINTER WEATHER ADVISORY FOR THE NORTHEAST PLAINS TODAY THROUGH
6 AM MDT TUESDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL
COLORADO.

.DAY ONE...TODAY AND TONIGHT

A STRONG STORM SYSTEM OVER NORTHEAST COLORADO WILL MOVE INTO
SOUTHWEST NEBRASKA BY TONIGHT.  THIS SYSTEM WILL PRODUCE SNOW IN THE
MOUNTAINS AND HIGHER VALLEYS WHICH WILL BE HEAVY AT TIMES THROUGH
TONIGHT.  TOTAL ACCUMULATIONS WILL RANGE FROM 8 TO 20 INCHES IN THE
MOUNTAINS WITH 5 TO 10 INCHES IN THE HIGHER VALLEYS.

OVER NORTHEAST COLORADO EXPECT A MIXTURE OF RAIN AND SNOW WHICH WILL
CHANGE OVER TO ALL SNOW BY EARLY AFTERNOON AND CONTINUE INTO THE
OVERNIGHT HOURS. SNOW ACCUMULATIONS OF 2 TO 4 INCHES WILL BE
POSSIBLE NORTHEAST OF A LINE FROM FORT COLLINS TO WIGGINS TO LAST
CHANCE. NORTHWEST WINDS OF 20 TO 35 MPH WITH GUSTS TO 55 MPH WILL
PRODUCE AREAS OF BLOWING SNOW WITH NEAR BLIZZARD CONDITIONS POSSIBLE
ALONG THE WYOMING...NEBRASKA BORDER THIS AFTERNOON AND EVENING. IN
THOSE AREAS THAT RECEIVED LITTLE SNOWFALL OVER THE PLAINS...AREAS OF
BLOWING DUST WILL POSSIBLY REDUCE VISIBILITIES TO UNDER A MILE AT
TIMES.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

ON TUESDAY LOOK FOR SNOWFALL IN THE MOUNTAINS AND THE RAIN AND SNOW
ON THE HIGH PLAINS TO DIMINISH DURING THE DAY. THE HIGH COUNTRY
COULD STILL SEE A FEW MORE INCHES OF SNOW BY THE AFTERNOON. IN
ADDITION EXPECT GUSTY NORTHWEST WINDS TO CONTINUE PARTICULARLY ON
THE FAR NORTHEAST PLAINS WHERE GUSTS MAY APPROACH 50 MPH.

THERE WILL BE ANOTHER CHANCE FOR SNOW...GUSTY WINDS AND COLDER
TEMPERATURES ON THURSDAY AND FRIDAY AS ANOTHER POTENTIALLY STRONGER
PACIFIC STORM SYSTEM DROPS SOUTH OVER THE FOUR CORNERS REGION.
SHOULD THIS STORM TAKE AN EASTWARD TRACK ACROSS SOUTHERN COLORADO AS
SOME FORECAST MODELS INDICATE...AREAS EAST OF THE CONTINENTAL DIVIDE
COULD SEE SIGNIFICANT SNOWFALL DURING THE DAY THURSDAY AND THURSDAY
NIGHT.  HOWEVER...AT THIS TIME THE EXACT TRACK AND STRENGTH OF THIS
STORM REMAINS QUITE UNCERTAIN.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT.

MEIER/BAKER