Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 010322
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
922 PM MDT TUE MAR 31 2015

.UPDATE...
ISSUED AT 922 PM MDT TUE MAR 31 2015

QUICK LOOK AT NEW MODELS AS THEY COME IN SHOWS THAT THE EVENT FOR
THURSDAY IS STILL ON TRACK. THE OPEN TROUGH IS FORECAST TO SWING
ACROSS THE STATE WITH GOOD COLD AIR ADVECTION AND FALLING
TEMPERATURES AT ALL LEVELS. THE POSITIONING OF THE STRONG UPPER
JET IS STILL FAVORABLE...ACROSS THE SOUTHERN HALF OF THE STATE.
NORTHEAST COLORADO WILL BE UNDER THE LEFT EXIT REGION OF THE
JET...FAVORABLE FOR RISING MOTIONS OVER THE FORECAST AREA. BANDS
OF PRECIPITATION ARE GOING TO BE A STRONG POSSIBILITY...GIVEN THE
UNI-DIRECTIONAL VERTICAL SHEAR PROFILE. MODEL SOUNDINGS SHOW
TEMPERATURES IN THE DENVER AREA DROPPING BELOW THE FREEZING POINT
LATE THURSDAY AFTERNOON. OH YEAH...AND GOOD UPSLOPE FLOW AT LOW
LEVELS IS GOING TO BE IN PLACE TOO. NO NEED TO MAKE ANY CHANGES TO
THE FORECAST AT THIS POINT.

IN THE SHORTER TERM...MOSTLY CLEAR SKIES THIS EVENING WILL GIVE
WAY TO GRADUALLY INCREASING MOISTURE ALOFT AND PARTLY CLOUDY SKIES
BY SUNRISE. NO CHANGES ARE NEEDED IN THE SHORT TERM EITHER AS
INCREASING CLOUDINESS SHOULD HELP TEMPERATURES TO REMAIN MILD
OVERNIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 320 PM MDT TUE MAR 31 2015

VERY DRY AIRMASS IN PLACE THIS AFTERNOON WITH WARM TEMPERATURES IN
THE MID 70S TO LOWER 80S. LOOKS TOO DRY FOR THUNDERSTORMS TODAY
SO WILL LEAVE FORECAST DRY. STRONGER SOUTH TO SOUTHWEST WINDS WILL
DEVELOP ON THE PLAINS TONIGHT BUT SHOULD BE ENOUGH HUMIDITY
RECOVERY TO NOT NEED ANY FIRE HILITES ACROSS THE PLAINS.

THE HIGH PRESSURE RIDGE AXIS ALOFT IS ACROSS COLORADO THIS
AFTERNOON AND WILL BE SHIFTING EAST INTO THE CENTRAL PLAINS
TONIGHT AND WEDNESDAY. THIS WILL BE REPLACED WITH STRONGER
WESTERLY FLOW ALOFT TONIGHT ALONG WITH INCREASING MIDDLE AND HIGH
LEVEL MOISTURE. CROSS SECTIONS ALSO SHOW INCREASING WINDS IN THE
MOUNTAINS TONIGHT. ALREADY SEEING SOME GUSTS IN THE 30-40 MPH
RANGE OVER MOUNTAIN PASSES THIS AFTERNOON.

A FRONTAL BOUNDARY WILL BEGIN TO MOVE ACROSS NORTHEAST COLORADO
WEDNESDAY AFTERNOON AS WINDS SHIFT NORTH AND NORTHEAST. THIS
COMBINED WITH SOME INCREASE IN MOISTURE AND MARGINAL INSTABILITY
WILL BRING A THREAT OF SHOWERS AND EVEN A FEW THUNDERSTORMS TO THE
AREA. WITH APPROACHING JET ALOFT INTO WESTERN COLORADO BY LATE
AFTERNOON AND WEAK UPWARD ASCENT WILL BUMP POPS UP A BIT MOST
AREAS BY LATE WEDNESDAY AFTERNOON.

THERE IS SOME MARGINAL FIRE WEATHER CONCERNS ACROSS SOUTHERN
LINCOLN COUNTY WEDNESDAY AFTERNOON WITH SOME GUSTS AROUND 20 MPH
AND LOW HUMIDITIES. THE AREAL AND TIME EXTEND LOOK TOO SMALL FOR
A FIRE WEATHER HILITE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 320 PM MDT TUE MAR 31 2015

BEING UNDER THE LEFT EXIT REGION OF THE JET ALONG WITH CAPES
AROUND 200-400 J/KG...EXPECT SHOWERS AND A FEW THUNDERSTORMS TO
CONTINUE WEDNESDAY EVENING...ESPECIALLY OVER THE NORTHEASTERN
PLAINS. THE SIMULATED NAM IR IMAGERY NICELY SHOWS A FEW STORMS
HEADING EAST-NORTHEAST ACROSS THE PLAINS. THE SURFACE FLOW BEHIND
THE AFTERNOON`S COLD FRONT WILL TURN MORE UPSLOPE THROUGH THE
NIGHT WHILE COLD AIR PUSHES SOUTH INTO THE AREA. THE EASTERN FRONT
RANGE MOUNTAINS AND FOOTHILLS WILL START TO SEE THE TRANSITION
FROM SHOWERS TO MORE STRATIFORM PRECIP WEDNESDAY EVENING...WITH
SNOW LEVELS BEGINNING AROUND 9500 FT MSL AND DROPPING TO NEAR 6000
FT BY SUNRISE. UPWARD QG VERTICAL VELOCITY WILL START INCREASING
AFTER MIDNIGHT TO SPREAD RAIN OVER THE URBAN CORRIDOR AND ADJACENT
PLAINS. ACCORDING TO FORECAST SOUNDINGS...SHOULDN`T SEE ANY
SNOWFLAKES MIX IN OVER THE PLAINS UNTIL NEAR SUNRISE OR SO.

UPWARD QG VERTICAL VELOCITY REALLY INCREASES THURSDAY...AND THE
AIRMASS BECOMES POTENTIALLY UNSTABLE AND WILL ALLOW FOR THE
POTENTIAL OF BANDING. THE JET WILL BE OVER SOUTHERN COLORADO...NOT
THE BEST POSITION...HOWEVER ENOUGH VERTICAL SHEAR AND QG SHOULD
NEGATE THAT. THERE ARE HINTS OF THIS IN THE MODEL PRECIP PATTERNS
AS WELL. RAIN AND SNOW WILL INCREASE DURING THE SNOW...WITH SNOW
LEVELS WAVERING BETWEEN 5000 AND 6000 FT. IF BANDING OR CONVECTION
DOES OCCUR...THIS COULD PRODUCE EXTRA COOLING TO CHANGE RAIN OVER
TO SNOW...BUT LIKELY IN NARROW BANDS OVER THE PLAINS. LOWERED MAX
TEMPERATURES THURSDAY DUE TO MODEL TRENDS...WHICH MAY HELP THE
POSSIBILITY OF MORE SNOW TO RAIN. THE UPPER TROUGH WILL BEGIN
MOVING OUT OF THE AREA THURSDAY EVENING SLOWLY...WITH COLDER
TEMPERATURES PUSHING SOUTH INTO THE STATE. LOOK FOR RAIN TO CHANGE
OVER TO ALL SNOW FOR THE EVENING AND NIGHT...TO DIMINISH FRIDAY
LATE MORNING. CURRENT THINKING FOR SNOWFALL TOTALS WILL BE LESS
THAN 2 INCHES OVER THE EASTERN PLAINS...2 TO 4 INCHES FOR AREAS
CLOSER TO THE FOOTHILLS AND PALMER DIVIDE...3 TO 6 INCHES FOR THE
FOOTHILLS...AND 5 TO 10 INCHES FOR THE MOUNTAINS. THIS IS A VERY
EARLY BROAD FORECAST AS THE POTENTIAL BANDING WILL VARY THIS QUITE
A BIT...AND RECENT WARM TEMPERATURES WILL MELT QUITE A LOT OF THE
SNOW THAT FALLS INITIALLY...AND POSSIBLY THROUGH THE STORM.
TEMPERATURES BELOW FREEZING FRIDAY NIGHT MAY ALLOW FOR SOME ROADS
TO HAVE ICE FORM.

FRIDAY WILL REMAIN COOL BUT WILL DRY OUT WITH SKIES CLEARING. LOOK
FOR TEMPERATURES TO REMAIN COOLER THAN AVERAGE FOR THE DAY.
SATURDAY THROUGH MONDAY WILL RETURN TO WARM AND DRY WEATHER.
TUESDAY WILL SEE ANOTHER PACIFIC SYSTEM APPROACH FOR A SLIGHT
CHANCE OF SHOWERS IN THE MOUNTAINS.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z WEDNESDAY EVENING)
ISSUED AT 922 PM MDT TUE MAR 31 2015

CLOUDINESS WILL GRADUALLY INCREASE OVERNIGHT AS MOISTURE ALOFT
MOVES IN. WINDS WILL BE OUT OF THE SOUTH THE REST OF THE NIGHT. A
WEAK DISTURBANCE ALOFT WILL BE MOVING ACROSS THE FRONT RANGE
THROUGH THE DAY...CAUSING THE AIRMASS TO DE-STABILIZE IN THE
AFTERNOON. ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP AS MODEL
SOUNDINGS INDICATE CAPE VALUES IN EXCESS OF 500 J/KG DURING THE
LATE AFTERNOON HOURS. SHOWERS AND THUNDERSTORMS WILL BE HIGH
BASED...MEANING THE PRIMARY THREAT FROM SHOWERS WILL BE GUSTY
DOWNBURST WINDS.

&&

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

$$

UPDATE...DANKERS
SHORT TERM...ENTREKIN
LONG TERM...KRIEDERMAN
AVIATION...DANKERS


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