Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 302247
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
347 PM MST FRI JAN 30 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 347 PM MST FRI JAN 30 2015

LIGHT SNOW MAKING ITS WAY NORTHEASTWARD TO ABOUT THE EISENHOWER
TUNNEL AT THIS TIME WITH A LARGE AREA OF PRETTY LIGHT
PRECIPITATION OVER WEST CENTRAL COLORADO. MOST VALLEY LOCATIONS
ARE SEEING SOME RAIN OR SNOW THOUGH...SO I WILL HANG ON TO THE
CHANCES OF LIGHT RAIN OR SNOW WE HAVE OVERNIGHT FOR DENVERWHICH
ARE HIGHER THAN MODEL GUIDANCE. EXPECTATION IS ONLY A FEW
HUNDREDTHS OF AN INCH OF LIQUID THOUGH...DRIPPING RAIN AND MAYBE A
FRACTION OF AN INCH OF SNOW OVERNIGHT. TEMPERATURES WILL STRUGGLE
TO COOL WITH THE CLOUD COVER...BUT SOME EVAPORATIVE COOLING WILL
HELP...PROBABLY COLD ENOUGH FOR A CHANGEOVER TO SNOW IN MOST
PLACES BUT WITH THE PRECIP BEING LIGHT THERE COULD STILL BE SOME
RAIN. LEFT THE PREVIOUS FORECAST LOWS ALONE.

FOR SATURDAY...CURRENT BATCH OF LIFT SLIDES EAST OF US WITH SOME
DRYING...COULD SEE SOME BREAKS IN THE CLOUDS. THEN
ANOTHER...WEAKER...AREA OF WARM ADVECTION WILL PASS US BY TO THE
SOUTHEAST. PRECIPITATION WITH THIS WILL LIKELY STAY OVER SOUTHEAST
COLORADO INTO KANSAS...BUT I WILL KEEP SLIGHT CHANCES FOR OUR
AREA. I DID RAISE TEMPERATURES SLIGHTLY WITH A WARM START TO THE
DAY EXPECTED AND A LITTLE SUNSHINE OR AT LEAST THINNING OF THE
CLOUDS EXPECTED.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 347 PM MST FRI JAN 30 2015

|MODELS SHOW A SPLIT FLOW OVER THE WESTERN HALF OF THE UNITED STATES
SATURDAY NIGHT WITH A LARGE UPPER LOW OVER NORTHERN MEXICO AND A
DEVELOPING UPPER TROUGH OVER THE NORTHERN ROCKIES AND GREAT PLAINS
STATES. THIS TROUGH WILL SEND A SHORT WAVE AND ASSOCIATED COLD FRONT
INTO NORTHEASTERN COLORADO LATE SATURDAY EVENING. UPSLOPE FLOW
BEHIND THE FRONT COMBINED WITH SOME WEAK LIFT COULD PRODUCE SOME
SNOW SHOWERS ACROSS NORTHEASTERN COLORADO OVERNIGHT SUNDAY INTO
SUNDAY MORNING...WITH THE BEST CHANCE OVER THE PALMER DIVIDE AND
SOUTHERN FOOTHILLS. AT THIS TIME...SNOWFALL AMOUNTS WITH THIS SYSTEM
LOOK TO BE LIGHT WITH AMOUNTS FROM A TRACE TO ONE HALF INCH IN MOST
LOCATIONS.

BY MONDAY MORNING WIND AND SNOW INCREASE IN THE MOUNTAINS AS A MOIST
NORTHWESTERLY FLOW ALOFT DEVELOPS OVER COLORADO. THIS PATTERN SHOULD
BRING A GOOD CHANCE OF SNOW THROUGH WEDNESDAY. THERE ALSO LOOKS TO
BE THE POTENTIAL FOR HIGH WINDS IN THE MOUNTAINS AND FOOTHILLS ON
MONDAY AS A MOUNTAIN WAVE SETS UP. THE NAM CROSS SECTIONS SHOWS A
75+KTS CROSS MOUNTAIN FLOW JUST BELOW MOUNTAIN TOP LEVEL MONDAY
MORNING...WHICH WOULD KEEP THE STRONGEST WINDS OVER THE THE HIGHER
FOOTHILLS AND EASTERN SLOPES OF THE MOUNTAINS. IN ADDITION...THE
DOWNSLOPE FLOW SHOULD WARM TEMPERATURES TO ABOVE NORMAL VALUES ON
THE PLAINS...ESPECIALLY AREAS CLOSER TO THE FOOTHILLS.


BY WEDNESDAY...THERE IS SOME MODEL DIVERGENCE BETWEEN THE GFS AND
THE ECMWF. OVERALL THE PATTERN BETWEEN THE MODELS LOOK
SIMILAR...HOWEVER THE LOCATION OF THE UPPER LEVEL JET IS DIFFERENT.
AT 12Z WEDNESDAY...THE GFS HAS TWO JET STREAKS...ONE OVER NW
NEVADA...WITH ANOTHER STRETCHING FROM EASTERN WYOMING EASTWARD INTO
THE CENTRAL PLAINS. THIS PUTS NORTHERN COLORADO IN A FAVORABLE AREA
FOR LIFT. THIS LIFT COMBINED WITH PLENTY OF PLENTY OF MOISTURE AND
WEAK UPSLOPE WOULD PRODUCE PRECIPITATION FROM DENVER NORTH TO THE
WYOMING BORDER...WHICH IS DEPICTID BY THE MODEL. THE ECMWF SHOWS THE
JET OVER NORTHEAST WYOMING...WITH NOT MUCH LIFT OVER THE REGION AND
THE MAIN PRECIPITATION BAND FURTHER TO THE NORTH OVER WYOMING. FOR
NOW HAVE ONLY ADDED A CHANCE OF POPS IN THE NORTHERN MOUNTAINS AND A
SLIGHT CHANCE OVER THE PLAINS. WARMER AND DRIER WEATHER IS EXPECTED
ACROSS THE FRONT RANGE URBAN CORRIDOR LATE IN THE WORK WEEK AS UPPER
LEVEL HIGH PRESSURE COMBINES WITH DOWNSLOPE FLOW.|

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z SATURDAY LATE AFTERNOON)
ISSUED AT 347 PM MST FRI JAN 30 2015

CEILINGS WILL LOWER THIS EVENING...INSTRUMENT APPROACHES TO KDEN
MAY BE NEEDED AFTER 03Z. AREAS OF MVFR CEILINGS IN LIGHT SNOW WILL
DEVELOP BY 06Z WITH LOCALIZED IFR. CONDITIONS ARE EXPECTED TO
IMPROVE SATURDAY MORNING WITH SNOW OUT OF THE AREA AND VFR
CONDITIONS BY 16Z. ANY SNOW ACCUMULATION IS EXPECTED TO BE LESS
THAN AN INCH.

&&

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

$$

SHORT TERM...GIMMESTAD
LONG TERM...JK
AVIATION...GIMMESTAD


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