Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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000
FXUS65 KBOU 211849
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1249 PM MDT TUE OCT 21 2014

.UPDATE...
ISSUED AT 958 AM MDT TUE OCT 21 2014

HAVE UPDATED GRIDDED FORECAST TO ALIGN BETTER WITH CURRENT
CONDITIONS...WHICH INCLUDED PUTTING IN ISOLATED SHOWERS ALREADY IN
THE MOUNTAINS THAT ARRIVED SLIGHTLY EARLIER THAN EXPECTED. LOOKS
LIKE THE FOG OVER LINCOLN COUNTY WAS VERY LOCALIZED AND DID NOT
LAST LONG AS INCOMING MIDLAYER CLOUD COVER LIKELY HELPED
DISSIPATE IT. OTHERWISE...FORECAST IS ON TRACK.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 325 AM MDT TUE OCT 21 2014

UPPER LEVEL TROUGH IS CURRENTLY OVER NORTHWEST NEVADA AND WILL LIFT
INTO MONTANA BY THIS EVENING. THIS WILL TAKE THE MAJORITY OF LIFT
AND MOISTURE WITH IT. EXPECT WEAK LIFT TO MOVE ACROSS COLORADO THIS
AFTERNOON AND TONIGHT...MAINLY FROM QG ASCENT AND A PACIFIC COLD
FRONT. AIRMASS WILL ALSO BE SLIGHTLY UNSTABLE WITH CAPES MAINLY
UNDER 300 J/KG. ALSO...LAPSE RATES WILL BE STEEPER THAN 7 J/KG FROM
THE SURFACE TO 400MB. NOTHING GREAT BUT ENOUGH FOR SCATTERED SHOWERS
AND PERHAPS A FEW WEAK THUNDERSTORMS.

PACIFIC MOISTURE WILL INCREASE THIS AFTERNOON OVER THE MOUNTAINS.
THIS COMBINED WITH THE LIFT AND INSTABILITY SHOULD PRODUCE SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS THIS AFTERNOON. MEANWHILE FOR THE
FRONT RANGE AND EASTERN PLAINS...IT WILL BE MOSTLY SUNNY AND WARM
THROUGH MID AFTERNOON WITH HIGHS IN THE 70S. THE CLOUDS AND
CONVECTION WILL SPREAD EAST ONTO THE FRONT RANGE LATE THIS AFTERNOON
AND THIS EVENING. MOISTURE AND LIFT IS LIMITED WITH THIS SYSTEM SO
WILL KEEP POPS GENERALLY SCATTERED OR LESS ACROSS EASTERN COLORADO.
THE MOUNTAINS WILL HAVE THE BEST CHANCE AT RECEIVING PRECIPITATION
WITH POPS IN THE 40 TO 70 PERCENT RANGE. THIS SYSTEM WILL CONTINUE
TO MOVE EASTWARD TONIGHT. THE BEST CHANCE FOR RAIN OVER THE
NORTHEAST CORNER WILL OCCUR AFTER MIDNIGHT. DUE TO CLOUDY SKIES
TONIGHT...EXPECT MILD OVERNIGHT LOWS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 325 AM MDT TUE OCT 21 2014

A WK UPPER LEVEL TROUGH WILL MOVE EAST OF THE AREA ON WED WITH WLY
FLOW ALOFT.  THERE IS SOME WK MID LVL QG ASCENT IN THE MORNING OVER
THE PLAINS WHICH MAY PRODUCE A CHC OF SHOWERS.  IN THE MTNS WK
OROGRAPHICS COMBINED WITH SOME LINGERING MOISTURE WILL LEAD TO A CHC
OF SHOWERS AS WELL THRU THE AFTN HOURS.  BY AFTN THERE MAY BE ENOUGH
INSTABILITY OVER NERN CO FOR A SLIGHT CHC OF SHOWERS/TSTMS.  AS FOR
HIGHS WILL KEEP READINGS IN THE UPPER 60S TO NEAR 70 OVER THE PLAINS.

BY THU AN UPPER LEVEL RIDGE WILL BEGIN TO BUILD ACROSS THE SRN
ROCKIES AND THEN EXPAND NORTHWARD INTO THE AREA ON FRI.  THIS WILL
LEAD TO A DRY WX PATTERN WITH A WARMING TREND. HIGHS ON THU WILL
RISE INTO THE MID TO UPPER 70S OVER NERN CO WITH UPPER 70S TO
LOWER 80S POSSIBLE ON FRI.

ON SAT THE UPPER LEVEL RIDGE WILL SHIFT A BIT FURTHER EAST WITH
INCREASING SWLY FLOW ALOFT.  THIS WILL LEAD TO ANOTHER DRY DAY WITH
ABV NORMAL TEMPS CONTINUING AS READINGS ONCE AGAIN RISE INTO THE
UPPER 70S TO LOWER 80S ACROSS NERN CO.  FOR SUN INTO SUN NIGHT BOTH
THE ECMWF AND GFS SHOW AN UPPER LEVEL TROUGH MAY AFFECT THE AREA.
THE ECMWF IS STRONGER WITH THIS FEATURE VS THE GFS.  FOR NOW WILL
MENTION A CHC OF PCPN IN THE MTNS WITH A SLIGHT CHC OVER THE REST OF
THE AREA WITH THE MAIN FOCUS LATE SUN AFTN THRU SUN NIGHT.  A WEAK
FNT MAY MOVE INTO NERN CO ON SUN WHICH MAY DROP TEMPS BACK INTO THE
UPPER 60S TO LOWER 70S.

FOR MON THE ECMWF STILL HAS THE UPPER LEVEL TROUGH AFFECTING THE
AREA WHILE THE GFS MOVES IT EAST OF THE AREA.  FOR NOW WILL JUST
MENTION SOME LOW POPS.  MEANWHILE BOTH MODELS DO SHOW ANOTHER SHOT
OF COOLER AIR WHICH WOULD DROP HIGHS BACK TO OR SLIGHTLY BLO NORMAL
OVER NERN CO.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z WEDNESDAY LATE AFTERNOON)
ISSUED AT 1249 PM MDT TUE OCT 21 2014

A WEAK DENVER CYCLONE HAS FORMED EARLY THIS AFTERNOON NEAR OR JUST
SOUTHWEST OF KDEN...MAKING WIND DIRECTION FORECASTING
CHALLENGING FOR THE NEXT FEW HOURS. IT APPEARS AS IT WILL HANG
AROUND FOR AT LEAST THROUGH 20Z BEFORE THE CONVECTIVE SHOWERS
ALREADY FORMING OVER THE MOUNTAINS AND FOOTHILLS PUSH OFF ENOUGH
TO SWITCH ALL THE LIGHT AND VARIABLE WINDS TO BE
WEST...POTENTIALLY GUSTY FROM OUTFLOW. THIS PUSH IS STILL DEPICTED
IN HIRES MODELS AROUND 21-23Z. WESTERLY WINDS SHOULD DECREASE
SLIGHTLY BEFORE ANOTHER NORTHERLY PUSH COMES AFTER 09Z FROM MAIN
ASSOCIATED COLD FRONT. WINDS SHOULD END UP UPSLOPE BY THE LATE
MORNING TO AFTERNOON.

CLOUDS WILL CONTINUE TO INCREASE AS A PACIFIC SYSTEM MOVES INTO
COLORADO. THIS SYSTEM WILL BRING MOSTLY CLOUDY SKIES AND SCATTERED
SHOWERS AFTER 22Z AND INTO TUESDAY. NOT MUCH LOW LEVEL MOISTURE
WITH THIS SYSTEM...SO EXPECT CEILINGS TO REMAIN ABOVE 6000 FEET
THROUGH TONIGHT. A FEW SHOWERS MAY CONTINUE OVERNIGHT THEN AGAIN WEDNESDAY
AFTERNOON AS UPSLOPE FLOW IS EXPECTED TO DEVELOP. CEILINGS SHOULD
STAY ABOVE 6000FT.

&&

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

$$

UPDATE...KRIEDERMAN
SHORT TERM...MEIER
LONG TERM...RPK
AVIATION...KRIEDERMAN



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