Parker Area Weather Forecasts

Area Forecast Discussion (National Weather Service)

     



AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
312 PM MST MON JAN 5 2009

.SHORT TERM...REAL DATA INDICATING MIDDLE AND HIGH CLOUDINESS MOVING
ACROSS THE FORECAST AREA AT THIS TIME.  RADAR INDICATING LITTLE OR
NO PRECIPITATION OVER THE FORECAST AREA RIGHT NOW...BUT A DECENT
WIND SIGNATURE CAME UP JUST EAST OF THE DIVIDE IN BOULDER COUNTY
SINCE AROUND 1 PM MDT.  WIND GUSTS ARE MAINLY IN THE 30 TO 50 MPH
RANGE RIGHT NOW OVER THE FOOTHILLS AND IMMEDIATE PLAINS.  THERE WERE
A COUPLE 60 MPH PLUS GUSTS AT ROCKY FLATS AND THE NCAR MESA LAB.
AREA PROFILERS ARE CURRENTLY SHOWING A PERFECT DIRECTION ON THE
CROSS-BARRIER FLOW...AS WELL AS LITTLE DIRECTION OR SPEED SHEAR WITH
HEIGHT.  OVERALL A DECENT WIND SET UP FOR THE FOOTHILLS AND
IMMEDIATE PLAINS.  MODELS DO NOT HAVE THE UPPER TROUGH AXIS THROUGH
THE FORECAST AREA UNTIL 12Z TUESDAY MORNING...SOMEWHAT SLOWER THEN
YESTERDAY`S RUNS INDICATED.  THERE IS WEAK UPWARD MOTION PROGGED FOR
THE FORECAST AREA FROM NOW THROUGH ABOUT 12Z TUESDAY MORNING...THEN
DOWNWARD SYNOPTIC SCALE ENERGY ON TUESDAY.  THE LOW LEVEL PRESSURE
GRADIENT IS PROGGED TO DECREASE A BIT FROM ITS CURRENT CONDITION.
ALTHOUGH IT WILL STAY FAIRLY DECENT OVERNIGHT AND TUESDAY...ENOUGH
SO TO INSURE A DOWNSLOPING COMPONENT TO THE BOUNDARY LAYER FLOW FOR
MUCH OF THE FORECAST AREA.  FOR MOISTURE...BOTH MODELS HAVE DEEP
MOISTURE OVER THE MOUNTAINS ALL NIGHT INTO TUESDAY MORNING...THEN A
DECREASE SOMEWHAT.  THE EAST WILL JUST HAVE MAINLY UPPER LEVEL
MOISTURE MOVING OVER THROUGH THE TWO PERIODS.  THE QPF FIELDS DO
SHOW SOME MEASURABLE SNOWFALL FOR THE MOUNTAINS TONIGHT AND
TUESDAY.  FOR POPS...NONE FOR THE PLAINS.  IN THE MOUNTAINS...WILL
KEEP THE HIGH POPS GOING INTO TUESDAY MORNING...WITH THE MOISTURE
AND OROGRAPHIC ENHANCEMENT EXPECTED.  THERE IS NO APPRECIABLE COLD
AIR ADVECTION ...THE LAPSE RATES ARE POOR AND THE SYNOPTIC SCALE
ENERGY IS PRETTY WEAK.  AMOUNTS WILL BE UNDER ADVISORY NUMBER FOR
SURE.  ON TUESDAY WILL REDUCE THEM TO 60%S WITH THE MOISTURE
DECREASE.  AMOUNTS WILL BE LIGHT.  FOR WINDS...IT LOOKS LIKE THE
BEST HIGH WIND SET-UP GOES AWAY BY EARLY/MID EVENING.  NO
HIGHLIGHTS.  IT SHOULD STAY FAIRLY WINDY OVERNIGHT AND
TUESDAY...WILL MAKE SURE BLOWING SNOW IS MENTIONED IN THE HIGH
MOUNTAINS.  FOR TEMPERATURES...TUESDAY HIGHS LOOK TO BE 1-3 C COOLER
THAN THIS AFTERNOON`S READINGS.

.LONG TERM...JET CORE SHIFTS OVER THE AREA TUESDAY NIGHT WITH WINDS
ALSO INCREASING AT MOUNTAIN TOP LEVEL. WARM ADVECTION INTENSIFIES IN
THIS PERIOD...KEEPING FAIRLY STABLE AIR ABOVE THE MOUNTAINS. THERE
LOOKS TO BE A BIT LESS FLOW ALOFT THAN IN THE DECEMBER 29-30 EVENT
BUT THERE WILL BE A LITTLE STABLE LAYER AND POSSIBLY A CRITICAL
LAYER OR CLOSE TO IT UP HIGH WITH THE NORTHERLY JET. RAN THE BROWN-
WEAVER LOCAL WIND GUIDANCE AND GOT FAIRLY HIGH NUMBERS FOR
WEDNESDAY...A 40 PERCENT CHANCE OF 60 MPH IN BOULDER AND GUSTS TO 68
KNOTS IN FORT COLLINS...ABOUT AS HIGH AS THIS GUIDANCE GOES. DESPITE
WHAT IS AT FIRST A MARGINAL APPEARANCE...THERE MAY BE THE RIGHT
COMBINATION OF FACTORS FOR A STRONGER HIGH WIND EVENT. THREAT SHOULD
BEGIN WITH THE PASSAGE OF THE JET CORE...WHICH LOOKS TO BE AFTER 06Z
SO I WILL BEGIN A HIGH WIND WATCH AT MIDNIGHT TUESDAY NIGHT. IF THE
TIMING OF THE JET SPEEDS UP THIS MAY NEED TO BE ADJUSTED. EXPECT THE
THREAT WILL INITIALLY BE CONFINED TO THE IMMEDIATE VICINITY OF THE
FOOTHILLS...BUT WE ARE LACKING COLD AIR AT THE SURFACE ON THE PLAINS
SO IT COULD SPREAD EASTWARD BEHIND THE SHORTWAVE...ESPECIALLY DURING
THE DAY WEDNESDAY.

AS FOR SNOW...STABILITY WILL LIMIT ACCUMULATIONS. WNW DIRECTION WITH
SPEEDS OF 40 KNOTS IS FAVORABLE FOR THE RABBIT EARS PASS AREA...SO
WE WILL HAVE A WINTER STORM WATCH FOR THE SLOPOVER INTO ZONE 31. PUT
THE OTHER MOUNTAINS INTO THE HIGH WIND WATCH AS THE WIND SHOULD BE
THE MAIN FACTOR THERE.

SHORTWAVE RIDGE MOVES OVER THURSDAY WITH WARM TEMPERATURES...EVEN IN
THE MOUNTAINS WHERE THERE COULD BE SOME 40S IN PLACES THAT DO NOT
USUALLY SEE THEM IN MIDWINTER. STILL PRETTY GOOD AGREEMENT ON A
SHEARING SHORTWAVE ABOUT FRIDAY NIGHT...WITHOUT A LOT OF WIND OR
MOISTURE. MORE DISCREPANCIES AFTER THAT WITH SOME MODEL RUNS SHOWING
A RETURN OF THE NORTHWEST JET WITH DECENT COLD ADVECTION AND
MOISTURE ON SUNDAY OR MONDAY...OTHERS WITH THE BAGGY TROUGH SHIFTING
EASTWARD BUT A LESS DYNAMIC NORTHWEST FLOW BEHIND IT. FOR NOW WILL
SHOW SOME MOUNTAIN POPS AND A LITTLE COOLING...BUT IT COULD BE MORE.

&&

.AVIATION...VFR CONDITIONS EXPECTED FOR THE NEXT 12 HOURS.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...HIGH WIND WATCH MIDNIGHT TUESDAY
      NIGHT TO MIDNIGHT WEDNESDAY NIGHT FRONT RANGE MOUNTAINS/
      FOOTHILLS/ADJACENT PLAINS...ZONES 33..34>36..38..39.
     WINTER STORM WATCH TUESDAY NIGHT AND WEDNESDAY ZONE 31.

$$
RJK/CMG