Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 280317
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
917 PM MDT FRI MAR 27 2015

.UPDATE...
ISSUED AT 917 PM MDT FRI MAR 27 2015

ISOLATED CONVECTIVE LIGHT SHOWERS HAVE MOSTLY ENDED LATE THIS
EVENING. SKIES WILL CLEAR OVERNIGHT BUT LIGHT DOWNSLOPE COMPONENT
AND WARM ADVECTION WILL KEEP TEMPS QUITE MILD ALONG THE FRONT
RANGE.

UPDATE ISSUED AT 722 PM MDT FRI MAR 27 2015

ISOLATED SHOWERS HAD DEVELOPED IN A NARROW AREA FROM THE NORTHERN
MOUNTAINS AND FOOTHILLS TO AROUND FORT COLLINS/LOVELAND AND THEN
TO NEAR AND JUST EAST OF DIA. THEY APPEAR TO HAVE DEVELOPED ON
WEAK BOUNDARY LAYER CONVERGENCE AREA...WITH MORE WESTERLY FLOW TO
THE WEST OF THE SHOWERS AND MORE NORTHERLY FLOW TO THE EAST. 00Z
DENVER SOUNDING SHOWS 100-200 J/KG OF CAPE. IN ANY CASE...THERE IS
LITTLE IN THE WAY OF SYNOPTIC SCALE LIFT SO EXPECT THESE LIGHT
SHOWERS TO GRADUALLY DISSIPATE AFTER DARK AND COME TO AN END BY
9-10 PM.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 208 PM MDT FRI MAR 27 2055

AN UPPER LEVEL RIDGE WILL PREVAIL OVER THE REGION TONIGHT AND
SATURDAY. THIS WILL BRING DRY AND MILD CONDITIONS. THERE MAY BE A
FEW CLOUDS EARLY THIS EVENING OVER THE HIGHER TERRAIN AND FAR
NORTHEAST COLORADO...BUT THEY WILL DISSIPATE AS DRIER MOVES INTO THE
AREA. AIRMASS WILL CONTINUE THE WARM THE NEXT 24 HOURS. MOST
LOCATIONS WILL SEE LOWS TONIGHT ABOVE FREEZING ACROSS NORTHEAST
COLORADO. HIGH WILL BE WELL INTO THE 70S TOMORROW WITH 40S AND 50S
FOR THE MOUNTAINS. A SHORT WAVE TROUGH WILL MOVE ACROSS THE NORTHERN
ROCKIES SATURDAY. THIS SYSTEM WILL CAUSE WESTERLY WINDS TO INCREASE
DURING LATE IN THE DAY. ALONG THE WYOMING BORDER...GUSTS TO 30 MPH.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 208 PM MDT FRI MAR 27 2055

FOR THE SUNDAY-MONDAY TIME PERIOD...A SPLIT FLOW PATTERN POSITIONS
NERN COLORADO UNDER A WARM/DRY NWLY FLOW WITH DAY AND NIGHT TEMPS
RUNNING SEVERAL DEGREES ABOVE AVERAGE. ALTHOUGH THE PASSAGE OF A
WEAK SFC COLD FRONT DURING THE PRE-DAWN HOURS ON SUNDAY WILL LOWER
MAX TEMPS ON THE PLAINS BY 8-11 DEG F. COOLING WILL BE LESS
EVIDENT IN THE HIGH COUNTRY ESPLY WEST OF THE CONTINENTAL DVD WITH
A PREVAILING W-SWLY LOW-LEVEL FLOW. FOR MONDAY...SHOULD SEE TEMPS
REBOUND MAINLY EAST OF THE MTNS WHERE A WLY DOWNSLOPE FLOW AND
AMPLE SUNSHINE WILL LIKELY PUSH TEMPS BACK INTO THE LOW/MID 70S.
HIGH COUNTRY TEMPS WILL BE LITTLE CHANGED BUT STILL QUITE WARM FOR
THIS TIME OF YEAR...ONLY TO FURTHER ENHANCE SNOW MELT ON SOUTH
FACING SLOPES...AND POSSIBLY MAKE FOR SOME SLOPPY SKIING
CONDITIONS ON LOWER SLOPES.

ONLY GLITCH TO MONDAY`S FORECAST MAY COME IN THE FORM OF ISOLATED
LATE DAY CONVECTION OVER THE HIGHER TERRAIN ROUGHLY SOUTH OF I-70
WHICH THE LATEST GFS AND TO A LESSER DEGREE THE NAM NOW INDICATE AS
A RESPONSE TO MODERATELY UNSTABLE LAPSE RATES AND LOCAL OROGRAPHIC
FORCING IN THAT AREA. WHEREAS THE EURO MODEL KEEPS ANY QPF/PCPN WELL
SOUTH OF THE FCST AREA. THE PRESENT WEATHER/POP FCST GRIDS ALREADY
HAVE A SLIGHT CHANCE OF SHOWERS IN THE CNTRL MTN ZONE 34 AND SOUTH
PARK ZONE 37 MONDAY EVENING. BELIEVE I`LL ADD A SLIGHT CHANCE OF
SHOWERS IN THIS SAME AREA FOR LATE MON AFTERNOON. OTHERWISE DRY
EVERYWHERE ELSE.

LATER IN THE WEEK...MID-LEVEL SHORTWAVE RIDGE BUILDING OVER THE
INTER-MOUNTAIN WEST WILL KEEP LIGHT-MODERATE NWLY FLOW ALOFT OVER
THE FCST AREA MONDAY NIGHT THRU TUESDAY EVENING. MAX TEMPS ON
TUESDAY APPEAR SLIGHTLY WARMER THAN THE DAY BEFORE WITH EVEN MORE
SUNSHINE AND A DOWNSLOPE FLOW GRADIENT EAST OF THE MTNS. MODEL
GUIDANCE IS GIVING MAX TEMPS IN THE 70S ON THE PLAINS AND UPPER
40S/50S IN THE HIGH COUNTRY...THAT`S ROUGHLY 15-20 DEG F ABOVE
AVERAGE. REALLY CAN`T ARGUE WITH THAT. THEN CHANGES COME LATE ON
TUESDAY AND WEDNESDAY WHEN THE GFS...ECMWF...DGEX AND CANADIAN
MODELS SHOW A SHARPLY CURVED SHORTWAVE TROUGH RACING EASTWARD OVER
THE NRN ROCKIES. THIS TRACK PROJECTION IS FARTHER NORTH THAN WHAT
MODELS INDICATED YESTERDAY AT THIS TIME...BUT PROBABLY STILL CLOSE
ENOUGH TO COOL TEMPS...GENERATE CLOUDS AND PRODUCE SOME SHOWERS IN
THE HIGH COUNTRY AND A PERHAPS A GUSTY...MOSTLY DRY HIGH BASED
SHOWER OR TWO ON THE NEARBY PLAINS DURING THE AFTERNOON ON
WEDNESDAY. HOWEVER WHILE THE ECMWF ALSO INDICATES SLIGHT COOLING...
IT DOES NOT INDICATE ANY QPF/PCPN IN OUR AREA...PRETTY MUCH LIKE
YESTERDAY/S RUN INDICATED. FOR NOW WILL HOLD ONTO A SLIGHT CHANCE OF
SHOWERS IN THE HIGH COUNTRY TUESDAY NIGHT-WEDNESDAY NIGHT AND
NOTHING AT LOWER ELEVATIONS. WITH THE WAY THE MODELS HAVE BEEN
BEHAVING LATELY...THAT MAY CHANGE AS TIME GOES ON.

BY THE END OF THE WEEK...THE OVERALL TREND IN THE MODELS IS FOR
TROUGHING ROUGHLY OVER THE ROCKY MTN AND GREAT PLAINS REGIONS
THURSDAY INTO FRIDAY. THE EURO MODELS INDICATES THE LOWEST HEIGHTS
OVER THE PLAINS WHICH PLACES NERN COLORADO UNDER A SWIFT...
RELATIVELY COOL AND MOIST NWLY FLOW MAINLY ON THURSDAY. WHEREAS THE
GFS SHOW THIS TROUGH DEEPENING UPSTREAM OF COLORADO WHICH WOULD
DELAY ANY COOLING OR PRECIP TIL THURSDAY NIGHT OR FRIDAY WHEN THE
MODEL SHOWS THE UPPER TROUGH AND STG SFC COLD FRONT PASSING THROUGH
THE AREA. DUE TO SO MUCH UNCERTAINTY IN THE MODELS BEYOND
WEDNESDAY...WILL GO WITH LOW POPS AND A GENERAL DOWNWARD TREND IN
TEMPS. THAT SAID...CLIMATOLOGY TELLS US THAT ITS STILL CERTAINLY
POSSIBLE THAT SUCH A STORM COULD BRING SIGNIFICANT SNOWFALL TO THE
FRONT RANGE AND ADJACENT PLAINS.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z SATURDAY EVENING)
ISSUED AT 917 PM MDT FRI MAR 27 2015

WINDS WILL GRADUALLY TRANSITION TO DRAINAGE 04Z-06Z WITH END OF
SHOWER ACTIVITY. WINDS ARE EXPECTED TO TURN MORE WESTERLY AGAIN BY
18Z-20Z SATURDAY AND INCREASE TO AROUND 12-15 KNOTS WITH PEAK
HEATING. VFR CONDITIONS WILL PERSIST.

&&

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

$$

UPDATE...BARJENBRUCH
SHORT TERM...MEIER
LONG TERM...BAKER
AVIATION...BARJENBRUCH


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