Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 160435
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1035 PM MDT TUE APR 15 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 329 PM MDT TUE APR 15 2014

A BATCH OF HIGH LEVEL MOISTURE IS MOVING ACROSS EASTERN UTAH AND
WESTERN COLORADO IN THE FORM OF HIGH CLOUDINESS THIS AFTERNOON AND
WITH MINIMAL ASCENT MOST OF THIS WILL SKIP US AND MOVE OFF TO THE
PLAINS. THIS BIGGEST ROLE THIS MOISTURE IS HAVING IS TO BUST MY
AFTERNOON HIGH FORECAST...LIMITING MIXING JUST ENOUGH THAT THE
COOLER PBL IS WINNING OUT AND TEMPS STRUGGLING. THE MAIN CHALLENGE
IN THE SHORT TERM LIES UPSTREAM. WATER VAPOR CLEARLY SHOWING A
DIGGING WAVE MOVING ACROSS THE NORTHERN HIGH ROCKIES THIS
AFTERNOON...WITH A JET DRIVEN SYSTEM ON IT/S HEELS IN THE
NORTHEAST PACIFIC.

THIS FIRST SYSTEM TAKES THE STRONGEST LIFT TO OUR NORTH BUT DROPS A
TRAILING FRONT THROUGH OUR CWA OVERNIGHT...SETTLING OVER THE
SOUTHERN MOUNTAINS BY SUNRISE. AN INSTABILITY AXIS WILL STRETCH FROM
SOUTHEAST UTAH TO THE NORTHERN MOUNTAINS LATE THIS EVENING. ASCENT
FROM THE PASSING WAVE...FRONTAL FORCING AND INSTABILITY WILL COMBINE
OVER THE NORTHERN COLORADO MOUNTAINS AND EXPECT SNOW TO BE FOCUSED
MAINLY NORTH OF INTERSTATE 70. THE MOISTURE LOOKS TO OUTRUN THE
COLDER AIR SO EXPECT AMOUNTS TO BE IN THE 1 TO 3 INCH RANGE ABOVE
7500 FEET. THE FRONT WILL BE LOOSING DEFINITION AS IT DRIFTS FARTHER
SOUTH AND LARGE SCALE DYNAMICS MOVE ONTO THE PLAINS. DEFINITELY
LOOKS LIKE A DOWNTURN ON PRECIPITATION TOWARD THE EARLY TO MID
MORNING HOURS ON WEDNESDAY. THE INFLUX OF MOISTURE AND CLOUDINESS
WILL KEEP LOWS A BIT MORE MILD THAN THE PAST FEW MORNINGS AND
FREEZING TEMPERATURES IN THE LOWER VALLEYS SHOULD BE HELD AT BAY.

LARGE SCALE ASCENT WILL BE INCREASING SIGNIFICANTLY BY EARLY
TOMORROW AFTERNOON OVER WESTERN COLORADO AS THE UPSTREAM WAVE AND
JET CORE ARRIVE IN UNISON. THE WAA AHEAD OF THIS WAVE LOOKS TO PUSH
SNOW LEVEL BACK UP AND THE STALLED BOUNDARY OVER THE SOUTH LOOKS TO
LIFT BACK TOWARD THE CENTRAL MOUNTAINS. INSTABILITY NOT OUT OF THE
QUESTION BUT THETA-E PROFILES SUGGEST THAT IF ANY IS RELEASED IT
WILL SLANTWISE RATHER THAN UPRIGHT. PWATS MAX OUT AT AROUND 0.40
INCHES AS THE LIFT ARRIVES...JUST ABOVE NORMAL. THE CHALLENGE IS
TIMING OF MAX LIFT/PRECIPITATION BEING IN THE AFTERNOON WHEN ACCUMS
BELOW 9000 FEET LOOK DIFFICULT. MODEL TRENDS STILL PLACE THE HIGHEST
QPF OVER THE ELKS/NORTHERN SAWATCH AND THE HIGHEST POINTS ON THE
NORTHEAST SAN JUAN RANGE. SOME SNOW AMOUNTS ABOVE 10000 FEET MAY BE
OVER THE 5 INCH RANGE IN THESE AREAS. HOWEVER CONFIDENCE IN
WIDESPREAD SNOW AMOUNTS CAUSING IMPACTS TO TRAVEL OR MOUNTAIN
VALLEYS ARE TOO LOW TO PLACE IN HEADLINES ATTM. SNOW/GRAUPEL WILL
FALL IN MANY AREAS OF THE HIGH COUNTRY BUT EXPECT AMOUNTS TO
GENERALLY BE LIGHT. THE BULK OF THE FORCING AND MOISTURE WILL BE
REFOCUSING EAST OF THE DIVIDE BY WEDNESDAY EVENING WITH A QUICK
DOWNTURN IN PRECIPITATION EXPECTED AFTER SUNSET. SOME HIGH LEVEL
MOISTURE REMAINS...OVERNIGHT AND LOWS ATTM LOOK TO REMAIN JUST ABOVE
THE FREEZING MARK IN THE FRUIT BEARING VALLEYS.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 329 PM MDT TUE APR 15 2014

A PROGRESSIVE SPLIT FLOW WILL BRING TWO STORM SYSTEMS OVER THE NEXT
7-8 DAYS WITH SHORT LIVED RIDGES IN BETWEEN. MODELS ARE SHOWING
SIGNIFICANT VARIATION WITH DETAILS AS EARLY AS THIS WEEKEND...THOUGH
IT SEEMS SO FAR THIS SPRING THE FASTER GFS HAS BEEN VERIFYING WELL.

RIDGING BUILDS IN ON THURSDAY AND PASSES THURSDAY NIGHT. THEN THE
SUBTROPICAL JET STREAM USHERS IN A RELATIVELY MILD BUT MOIST OPEN
TROUGH FROM THE SW. LIGHT MOUNTAIN SHOWERS BEGIN FRIDAY AND BECOME
LIKELY ON SATURDAY ACROSS THE SOUTHERN MTNS. SNOW LEVELS REMAIN HIGH
AROUND 9KFT BUT WITH SIGNIFICANT ACCUMULATIONS ABOVE 10-11KFT.
THUNDERSTORMS ARE POSSIBLE SATURDAY AFTERNOON. SHOWERS DIMINISH
SATURDAY NIGHT AS THE NEXT RIDGE BUILDS INTO THE REGION. BUT THERE
IS ENOUGH AFTERNOON HEATING AND RESIDUAL MOISTURE FOR CONVECTIVE
SHOWERS TO FORM SUNDAY AND MONDAY AFTERNOONS...MAINLY OVER THE
COLORADO MTNS. TEMPERATURES ARE EXPECTED TO BE AT OR ABOVE NORMAL
EXCEPT PERHAPS OVER THE WEEKEND WHEN CLOUDS AND SHOWERS PRODUCE
COOLER AFTERNOONS.

THE NEXT MORE ORGANIZED PACIFIC TROUGH COMES ONSHORE NEXT TUESDAY.
THE GFS IS MUCH STRONGER AND FURTHER SOUTH THREATENING WIDESPREAD
MOUNTAIN SNOW AND VALLEY RAIN BY MID WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1034 PM MDT TUE APR 15 2014

A COLD FRONT PUSHES INTO NW CO/NE IS EXPECTED TO REACH THE I-70
CORRIDOR ABOUT 09Z-10Z...THEN LOSES DEFINITION AS IT CONTINUES TO
SLIP SOUTH. SCT TO NMRS -SHSN WITH OCNL MOUNTAIN TOP OBSCURATIONS
ARE EXPECTED OVER THE NRN AND CENTRAL MTNS WITH THE FRONT...BUT
LITTLE IF ANY PRECIPIATION WILL REACH THE VALLEYS. CIGS WILL BE
LOWERING BUT TAF SITES SHOULD REMAIN VFR THROUGH WED MORNING. A
SECOND DISTURBANCE WILL SWING ACROSS THE FORECAST AREA WED
AFTERNOON FOR A RESURGENCE OF SCT TO NMRS -SHSNRA MAINLY OVER THE
MOUNTAINS...AND ISOLD -SHRA FOR THE CENTRAL AND SOUTHERN CO
VALLEYS.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&

$$

SHORT TERM...15
LONG TERM...JOE
AVIATION...JAD



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