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000
FXUS65 KBOU 250443
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
943 PM MST TUE FEB 24 2015

.UPDATE...
ISSUED AT 942 PM MST TUE FEB 24 2015

UPSTREAM WEATHER MAKER LOOKS RATHER DISORGANIZED ON SATELLITE
THIS EVENING AND QG FIELDS SUPPORT THAT. HAVE SOME DOUBTS THAT
MTN AREAS WILL SEE ANY SNOW ACCUMULATION BEFORE MORNING...BUT WITH
NORTHWEST FLOW AND WITH MID-LEVELS BECOMING INCREASINGLY MOIST
AND UNSTABLE WITH CAA...WILL HOLD ONTO THE LIKELY POPS LATE
TONIGHT AND THE LOW SNOW AMTS IN MTN ZONES 31...33 AND 34.
OTHERWISE...A CANADIAN COLD FRONT IS MAKING ITS WAY SOUTHWARD
ACROSS CENTRAL MONTANA AND AT ITS PRESENT SPEED...IT SHOULD
MANAGE TO REACH NORTHERN SECTIONS OF THE CWA BY 12Z...IF NOT A TAD
EARLIER THAN THAT. BASED ON LATEST SATELLITE IMAGERY...SPED UP THE
INCREASE IN CLOUD COVER OVERNIGHT...MOST OF WHICH WILL BE MID AND
HIGH CLOUDS OVER THE PLAINS. NO CHANGES TO THE WINTER STORM WATCH
IN THE FRONT RANGE FOOTHILLS ZONES 35-36 AT THIS TIME. AS NEW
MODEL DATA ROLLS IN...THE DECISION TO ADD MORE HIGHLIGHTS WILL
HOPEFULLY BECOME CLEARER OVERNIGHT. 00Z NAM CONTINUES TO INDICATE
A BULLSEYE OF 7-14 INCH SNOW ACCUM OVER THE NRN FTHLS BY MIDDAY
THURSDAY. HOWEVER SNOW AMOUNTS OFF THE 00Z GFS STILL MUCH LOWER
THAN THOSE OFF THE NAM. WILL REFRAIN FROM MAKING ANY MEANINGFUL
ADJUSTMENTS TO SNOW TOTALS AT THIS TIME.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 321 PM MST TUE FEB 24 2015

THERE ARE NO CLOUDS OVER THE CWA RIGHT NOW. THE NEXT STORM`S
INITIAL BATCH OF CLOUDINESS IS OVER NORTHERN WYOMING RIGHT NOW
HEADING SOUTH-SOUTHEASTWARD. MODELS HAVE WEAK NORTHEASTERLY...
THEN NORTHWESTERLY...THEN WEST-NORTHWESTERLY FLOW ALOFT FOR THE
CWA TONIGHT THROUGH WEDNESDAY AFTERNOON. SPEEDS INCREASE A BIT ON
WEDNESDAY. THERE IS WEAK QG ASCENT PROGGED FOR THE CWA TONIGHT AND
WEDNESDAY MORNING...GETTING A BIT STRONGER FOR THE CWA BY
AFTERNOON. THE BOUNDARY LAYER FLOW WILL BE NORMAL DRAINAGE
OVERNIGHT...WITH A COLD FRONT AND NORTH-NORTHEASTERLY UPSLOPE
BEHIND IT BY AFTERNOON. FOR MOISTURE...THERE IS NONE EARLY THIS
EVENING...THEN IT INCREASES FROM NORTHWEST TO SOUTHEAST OVERNIGHT
AND WEDNESDAY. MOISTURE INCREASES AND DEEPENS DRAMATICALLY
THROUGH THE DAY WEDNESDAY. THE QPF FIELDS SHOW NOTHING THIS
EVENING...THEN A TAD IN THE MOUNTAINS OVERNIGHT. THERE IS A TAD
FOR THE MOUNTAINS AND NORTHERN PLAINS WEDNESDAY MORNING...WITH
SOME PROGGED FOR ALL THE CWA BY 00Z LATE AFTERNOON. WILL START
SOME MOUNTAIN POPS IN EARNEST AFTER MIDNIGHT TONIGHT. WIDESPREAD
SNOW CAN BE EXPECTED OVER ALL THE CWA BY LATE WEDNESDAY AFTERNOON
...SO HIGH POPS BY THEN. AMOUNTS MAY BE HIGH ENOUGH IN THE FOOTHILLS
...SO "WATCH" HIGHLIGHTS THERE LOOK GOOD. FOR TEMPERATURES...
WEDNESDAY`S HIGHS SHOULD BE 0-3 C COLDER THAN CURRENT READINGS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 321 PM MST TUE FEB 24 2015

SHORTWAVE AND JET STREAK WILL DROP ACROSS THE AREA WEDNESDAY
NIGHT. GETTING MIXED SIGNALS AS FAR AS THE SNOW POTENTIAL...NAM
HAS INSISTED ON GREATER INSTABILITY AND GENERATES A QUICK SHOT OF
HEAVY SNOW...OVER A FOOT...IN THE FOOTHILLS OVERNIGHT. LIGHTER
AMOUNTS ON THE PLAINS BUT STILL AN ENHANCED AREA MOVING OFF THE
FOOTHILLS INTO DENVER CORRESPONDING TO THE PERIOD OF NORTHEAST
WINDS IN THE EVENING. GFS HAS LESS INSTABILITY BUT STILL HAS
DECENT LIFT WITH LITTLE RESISTANCE TO THE VERTICAL MOTION...IT
STILL GENERATES 4 TO 7 INCHES OF SNOW ACROSS THE DENVER METRO AREA
BY THURSDAY AFTERNOON. EVERYTHING IS LIGHTER ON THE PLAINS THOUGH
THERE SHOULD BE A PERIOD OF SNOW WITH THE SHORTWAVE WEDNESDAY
NIGHT...AND THE NAM DOES HINT AT SOME LIGHT BANDED PRECIP
CONTINUING THURSDAY AS WELL. ENOUGH OF A THREAT FOR A WINTER STORM
WATCH FOR THE FOOTHILLS AS UPSLOPE ENHANCEMENT SHOULD BE
PROLONGED AND THE SNOW COULD BE VERY HEAVY FOR A WHILE WEDNESDAY
NIGHT. FOR ADJACENT AREAS THERE WILL BE SUBSTANTIAL
ACCUMULATIONS...BUT THE THREAT OF HEAVY SNOWFALL LOOKS LOWER...WE
MAY WIND UP WITH ADVISORIES FOR DENVER FOR A FAIRLY PROLONGED
LIGHT TO MODERATE SNOW.

TRENDED THE REST OF THE FORECAST TOWARD CLOUDIER AND COLD
CONDITIONS WITH HIGHER POPS. THE TROUGH DIGS INTO THE SOUTHWEST
AND LEAVES US IN COLD LOW LEVEL AIR WITH MOISTURE COMING OVER US
AT TIMES. FIRST PERIOD OF WEAK LIFT FROM WARM ADVECTION WILL
SPREAD INTO THE CENTRAL PART OF THE STATE THURSDAY AFTERNOON AND
ACROSS OUR AREA THURSDAY NIGHT...DECENT CHANCE OF LIGHT SNOW IN
THIS TIME ESPECIALLY MOUNTAINS AND SOUTH OF INTERSTATE 70. THERE
IS DECENT AGREEMENT ON A BIT OF SHORTWAVE RIDGING FRIDAY INTO
EARLY SATURDAY...BUT THERE WILL STILL BE SOME MOISTURE AND WEAK
LIFT SO THE SNOW MAY NOT STOP ALTOGETHER.

THERE IS ALSO DECENT AGREEMENT ON SHORTWAVES ROTATING AROUND THE
SOUTHWEST TROUGH WITH ONE OR TWO KICKING OUT OVER OR SOUTH OF US
THIS WEEKEND AS MORE ENERGY DROPS INTO THE BACK OF THE TROUGH AND
HOLDS THE LARGER SCALE TROUGH AXIS WEST OF US. THIS WOULD PROVIDE
ONE OR TWO MORE PERIOD WHERE LIGHT SNOW IS LIKELY IN THE
SATURDAY/SUNDAY TIME FRAME...AND MAINTAIN THE LOW LEVEL COLD AIR
AND CLOUD COVER. THIS PATTERN CONTINUES INTO NEXT WEEK...AGAIN
VARYING TIMING BUT THE CONSENSUS IS FOR THE LARGER TROUGH TO
WEAKEN AND COME ACROSS US MONDAY OR TUESDAY...BUT THEN YET ANOTHER
WEAK TO MODERATE STRENGTH TROUGH ON WEDNESDAY OR THURSDAY. WITH
THE WEST COAST RIDGE/EASTERN TROUGH PATTERN CONTINUING...WE MAY
SEE SOME IMPROVEMENT AFTER THAT OR WE MAY REMAIN IN THE STORM
TRACK BEYOND THAT. WINTER IS NOT GOING TO GIVE UP JUST YET.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z WEDNESDAY LATE AFTERNOON)
ISSUED AT 942 PM MST TUE FEB 24 2015

SLY WINDS AND INCREASING HIGH CLOUDS FOR THE NEXT SEVERAL HOURS.
SPEEDS GENERALLY UNDER 12 KTS. COLD FRONT UP IN MONTANA AT THIS
TIME WILL RACE SOUTH AND BE THROUGH NORTHEAST COLORADO BY MID-
MORNING. NORTH-NORTHWESTERLY WINDS IN THE WAKE OF THIS FRONT WILL
TURN NORTHEASTERLY DURING THE AFTERNOON. SHOULD SEE CEILINGS
STEADILY FALLING WHEN THIS HAPPENS...AND LIGHT SNOW DEVELOPING
OVER AND AROUND DIA BETWEEN 3 AND 5 PM MST. MAY ALSO SEE CEILINGS
LOWERING BELOW OVC010 WITH 1-2SM -SN VSBYS BY EVENING.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
MORNING FOR COZ035-036.

&&

$$

UPDATE...BAKER
SHORT TERM...RJK
LONG TERM...GIMMESTAD
AVIATION...BAKER