Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 120154
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
754 PM MDT THU SEP 11 2014

.UPDATE...
ISSUED AT 754 PM MDT THU SEP 11 2014

COLD MOIST AIRMASS WILL REMAIN OVER NORTHEAST COLORADO TONIGHT AND
INTO FRIDAY AFTERNOON. NORTHEAST WINDS WILL CONTINUE TO USHER IN
COLDER AIR. TEMPERATURES LOOK TO STAY IN THE 33 TO 37 DEGREE RANGE
LATE TONIGHT ALONG THE FRONT RANGE...AS THE LATEST HRRR AND RAP
INDICATE. HOWEVER...AREAS ABOVE 6000 FEET WILL LIKELY REACH
AND DROP FREEZING.

FORECASTING PRECIPITATION TYPE REMAINS VERY CHALLENGING. AIRMASS
WILL REMAIN SATURATED UP TO 10000 TO 13000 FEET MSL. THIS WILL
CONTINUE TO SUPPORT DRIZZLE ALONG THE FRONT RANGE. THE SATURATED
LAYER GENERALLY STAYS WARMER THAN -4C...WHICH MEANS NO ICE IN THIS
LAYER. SO UNLESS SOME SHOWERS FORM IN COLDER AREAS ABOVE THIS
LAYER...PRECIPITATION SHOULD REMAIN DRIZZLE. THERE IS SOME LIFT
OVERHEAD DUE TO THE JET AND IS PRODUCING A FEW SHOWERS. THIS WOULD
SUPPORT SOME RAIN...AND LATER TONIGHT SNOW. SO THINKING DRIZZLE WILL
BE THE MAIN PRECIPITATION TYPE OVERNIGHT. HOWEVER...SOME RAIN THIS
EVENING AND SNOW AFTER MIDNIGHT WILL BE SCATTERED ABOUT. BEST CHANCE
FOR THE RAIN AND SNOW WILL BE OVER THE EASTERN PLAINS WHERE THE BEST
LIFT WILL OCCUR. NOT EXPECTING MUCH IF ANY SNOW ACCUMULATION ALONG
THE FRONT RANGE. HOWEVER...OVER WASHINGTON AND LINCOLN COUNTIES...A
COUPLE OF INCHES WILL BE POSSIBLE IF A HEAVY BAND FORMS.

WILL TWEAK THE FORECAST TO SAY FOG AND DRIZZLE WITH A CHANCE FOR
RAIN AND SNOW FOR THE FRONT RANGE. SNOW WILL BE LIKELY OVER THE
EASTERN PLAINS LATE TONIGHT AND EARLY FRIDAY MORNING.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH FRIDAY)
ISSUED AT 1107 AM MDT THU SEP 11 2014

EVENTS ARE UNFOLDING ABOUT AS PLANNED. STILL AREAS OF DRIZZLE ON
THE PLAINS WITH SUNSHINE AND MILD TEMPERATURES WEST OF THE FRONT
RANGE. EXPECTED AREA OF LIFT DEVELOPING ALONG THE COLORADO/WYOMING
BORDER WITH SHOWERS BREAKING OUT AROUND CHEYENNE. SECONDARY FRONT
STRENGTHENING NOW ACROSS SOUTHEAST WYOMING WITH PRESSURE RISES IN
WYOMING AND FALLS IN SOUTHWESTERN COLORADO. THIS WILL PUSH COLDER
LOW LEVEL AIR INTO NORTHERN COLORADO LATER THIS EVENING. WITH THIS
TIMING I BACKED OFF A LITTLE ON THE TIME THE SNOW WILL
BEGIN...KEEPING IT NORTH OF BOULDER AND GREELEY UNTIL AFTER 10 PM.
WITH THE FORECAST HINGING ON A COUPLE OF DEGREES WE WILL KEEP RAIN
AND SNOW WORDING...BUT SUSPECT IT WILL CHANGE OVER TO ALL SNOW IN
MOST AREAS IN THE EARLY MORNING HOURS. THE SNOW WILL PROBABLY BE
ALL SOUTH OF INTERSTATE 76 BY SUNRISE AND OUT OF OUR AREA BY LATE
MORNING. EVEN WITH SOME BANDING THAT COULD PRODUCE MODERATE
SNOWFALL...GROUND TEMPERATURES ARE VERY WARM AND THE AIR WILL
BARELY BE COLD ENOUGH FOR SNOW...SO MOST PLACES WILL LIKELY JUST
HAVE A DUSTING ON THE GRASS. HARDEST HIT SPOTS COULD HAVE AN INCH
OR TWO ON THE GRASS...BUT STILL NOT EXPECTING ANY TRAVEL
ISSUES...EVEN IN THE FOOTHILLS THE GROUND IS PRETTY WARM.

FOR FRIDAY STRATUS MAY HANG IN ON THE STRENGTHENING SOUTHEAST FLOW
MUCH OF THE DAY...BUT STILL EXPECTING CLEARING LATE IN THE DAY.
IT WILL BE WARMING ALOFT AND MOUNTAIN TEMPERATURES WILL LIKELY
RECOVER TO TODAYS LEVELS...FORECAST FOR THE PLAINS LOOKS GOOD WITH
HIGHS AROUND 50 UNDER THE INVERSION.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 1107 AM MDT THU SEP 11 2014

UPSLOPE WILL CONTINUE FRIDAY EVENING AS THE SURFACE HIGH PRESSURE
CONTINUES TO MAKE ITS WAY SOUTH AND EAST INTO KANSAS. A SURFACE
TROUGH WILL DROP DOWN FROM WYOMING AND HELP TO TRANSITION THE
WINDS TO A MORE NORTHWEST DIRECTION AND HELP TO CLEAR OUT THE LOW-LYING
CLOUDS. THIS WARMER AIR COMBINED WILL DOWNSLOPING WINDS STARTING
AROUND 06Z ACCORDING TO THE MODELS WILL AID IN RADIATION COOLING
AND ALLOW SOME AREAS TO FORM PATCHY FOG EARLY SATURDAY MORNING.
AREAS OUT IN THE NORTHEAST PORTIONS OF THE CWA COULD SEE SOME
PATCHY FROST WITH THE DEWPOINTS GETTING CLOSE TO FREEZING BY 12Z
SATURDAY.

A SURFACE HIGH WILL MOVE NORTH FROM THE SOUTHWEST AND COMBINE WITH
AN UPPER LEVEL RIDGE MOVING IN TO START THE DRYING OUT FOR THE
WEEKEND. SATURDAY WILL BEGIN THE WARM UP WITH TEMPERATURES
REACHING BACK INTO THE 70S AND LOWER 80S BY SUNDAY. WITH INCREASED
MOISTURE IN THE MOUNTAINS...THERE IS A SLIGHT CHANCE OF
THUNDERSTORMS IN THE AFTERNOON.

MODELS ARE PICKING UP ON A WEAK UPPER LEVEL TROUGH THAT WILL BRING
A SURFACE FRONT DOWN INTO NE COLORADO MONDAY AFTERNOON. AS THE
FRONT MOVES INTO THE CWA FLOW WILL CHANGE TO A MORE EASTERLY TO
NORTHEASTERLY DIRECTION BRINGING COLD AIR DOWN AND PUTTING A BREAK
ON THE WARM UP FOR THE START OF NEXT WEEK. SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE DURING THE MORNING INTO THE
AFTERNOON MONDAY.

FOR TUESDAY AND WEDNESDAY UPPER LEVEL RIDGING WILL RETURN WITH
INCREASING TEMPERATURES AND JUST A SLIGHT CHANCE OF SHOWERS OVER
THE MOUNTAINS IN THE AFTERNOON.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z FRIDAY EVENING)
ISSUED AT 754 PM MDT THU SEP 11 2014

LOW CLOUDS WITH CEILINGS MAINLY LESS THAN 500 ARE EXPECTED TO
PREVAIL THROUGH 15Z AND THEN SLOWLY LIFT THROUGH THE DAY FRIDAY.
VISIBILITY WILL FALL THROUGH THE NIGHT...BOTTOMING OUT AT A QUARTER
TO A HALF MILE. PRECIPITATION IS EXPECTED TO BE MAINLY DRIZZLE
OVERNIGHT WITH A FEW PERIODS RAIN THIS EVENING AND SNOW AFTER
MIDNIGHT POSSIBLE. IF SNOW FALLS...ANY ACCUMULATION WILL BE VERY
LIGHT.

&&

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

$$

UPDATE...MEIER
SHORT TERM...GIMMESTAD
LONG TERM...BOWEN
AVIATION...MEIER



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