Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 112136
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
336 PM MDT FRI APR 11 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 336 PM MDT FRI APR 11 2014

AN UPPER LEVEL LOW CENTER OFF THE SRN CA COAST THIS EVENING WILL
CONTINUE TO WEAKEN...OPEN UP...AND MOVE EASTWARD OVER NM BY
SATURDAY NIGHT. IT SCOOTS BY TO OUR SOUTH JUST AHEAD OF A STRONG
SHORTWAVE TROUGH DROPPING SOUTHEAST FROM BRITISH COLUMBIA.
MOISTURE WITH THE SRN TROUGH IS LIMITED TO THE MID AND UPPER
LEVELS. WITH DAYTIME HEATING...THOUGH TEMPERED BY VEIL OF HIGHER
CLOUDS SATURDAY...EXPECT CONVECTIVE CLOUDS TO DEVELOP...ESPECIALLY
OVER THE HIGHER TERRAIN. ISOLATED TO SCATTERED SHOWERS CAN BE
EXPECTED OVER THE NORTHERN HALF SATURDAY AFTN AND EVENING...WITH
BETTER COVERAGE OVER THE SAN JUAN MOUNTAINS CLOSER TO THE SRN
TROUGHS PASSAGE. ISOLATED THUNDERSTORMS ALSO POSSIBLE. HARD TO SEE
MUCH IF ANY RAIN FALLING OVER THE LOWER VALLEYS WITH SUCH DRY AIR
BELOW 600 MB. SNOW LEVELS SATURDAY WILL BE ABOVE 8500 FEET...BUT
CONVECTION WILL DROP THE SNOW LEVEL LOCALLY LOWER. IN ANY
EVENT...WITH TEMPS IN THE 40S FOR HIGHER ELEVATIONS...HARD TO
IMAGINE LASTING ACCUMULATIONS. LOWER ELEVATIONS WILL HAVE ONE MORE
MILD DAY AHEAD OF THE COLD FRONT THAT WILL PASS SUNDAY.

SATURDAY NIGHT...THE AREA IS ESSENTIALLY IN BETWEEN THE DEPARTING
SRN TROUGH AND THE APPROACHING NRN TROUGH. WILL KEEP SCATTERED TO
NUMEROUS SHOWERS IN FORECAST FOR THE MOUNTAINS...WITH GREATEST
COVERAGE TRANSITIONING TO THE CENTRAL AND NORTHERN MOUNTAINS IN
THE SW FLOW AHEAD OF THE TROUGH. SNOW LEVELS WILL DROP TO AROUND
7000 FEET NORTH TO 8000 FEET SOUTH BY SUNDAY MORNING...WITH SOME
LIGHT ACCUMULATIONS OF 2 INCHES OR LESS.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 336 PM MDT FRI APR 11 2014

THE FIRST MORE SOUTHERLY WAVE WILL HAVE SHIFTED EAST OF THE AREA
BY THE START OF THE DAY SUNDAY....WITH THE SECOND AND STRONGER
UPPER TROUGH...AND ITS VIGOROUS COLD FRONT FAST APPROACHING. THE
COLD FRONT WILL BE ALONG OUR NORTHERN BORDER AT DAYLIGHT
SUN...THEN WILL PUSH ACROSS THE NORTHERN HALF OF THE FORECAST AREA
BY AROUND MIDDAY. IN ADDITION...A 700MB LOW WILL CLIP OUR
NORTHEAST CORNER LATE MORNING TO EARLY AFTERNOON. THE FRONT WILL
CONTINUE ACROSS THE REMAINDER OF THE FORECAST AREA THROUGH THE
AFTERNOON. THE UPPER TROUGH WILL FOLLOW WITH ENERGY DROPPING
SOUTHWARD ACROSS THE 4-CORNERS LATE IN THE AFTERNOON AND INTO THE
EVENING. THE TROUGH AXIS IS THEN PROGGED TO PASS EAST OF THE
CONTINENTAL DIVIDE BY AROUND MIDNIGHT...WITH SOME DIFFERENCES IN
MODEL TIMING. THIS FAST MOVING STORM SYSTEM SHOULD BRING A GOOD
ROUND OF MOUNTAIN SNOW TO THE AREA...WITH SNOW LEVELS FALLING INTO
THE HIGHER VALLEYS AS THE COLD FRONT PASSES. AIDED BY A DIURNAL
BOOST...AND INSTABILITY AS COLDER AIR ALOFT MOVES OVERHEAD...FEEL
THAT THUNDERSTORMS ARE AGAIN A POSSIBILITY. ANYWAY THE SEASON HAS
REACHED THE POINT WHERE THESE SYSTEMS HAVE BECOME MUCH MORE
CONVECTIVE. THIS CONVECTIVE NATURE WILL ALSO PRODUCE HEAVIER SNOW
BURSTS IN THE MOUNTAINS...AND HELP PUSH SNOW LEVELS LOWER. GRAUPEL
OR SNOW PELLETS WILL EXPECTED AT TIMES EVEN IN SOME OF THE LOWER
VALLEYS. EARLY IN THE DAY...SNOW WILL BE HEAVIEST OVER THE
NORTH...THEN SPREAD SOUTH WITH THE FRONT. BY LATE AFTERNOON THE
SOUTH WILL BECOME FAVORED AS ENERGY DROPS ACROSS THE SAN JUANS.
ALSO THE NORTH...ESPECIALLY THE PARK RANGE MAY SEE A MARKED
DOWNTURN AS AN EASTERLY FLOW DEVELOPS BEHIND THE 700MB LOW. SNOW
WILL DIMINISH FROM THE WEST DURING THE EVENING...LINGERING LONGEST
OVER THE CENTRAL AND SOUTHERN DIVIDE. FOR THE VALLEYS THE BEST
CHANCE OF SHOWERS WILL BE ON SUN AS THE FRONT PASSES.

FOR THIS PACKAGE HAVE ISSUED A WINTER WEATHER WATCH FOR THE
NORTHERN AND CENTRAL COLORADO MOUNTAINS WITH A FOOT OF SNOW
POSSIBLE. WHILE AMOUNTS ARE SOMEWHAT BORDERLINE...FEEL THAT THE
IMPACT WILL BE SIGNIFICANT DUE TO THE SUNDAY DAYTIME TIMING...THE
HEAVY CONVECTIVE SHOWERS...AND THE RECENT WARM APRIL CONDITIONS.

TEMPERATURES IN THE LOWER VALLEYS WHERE THE GROWING SEASON HAS
BEGUN WILL HAVE TO BE WATCHED FOR SUNDAY NIGHT. GUIDANCE NUMBERS
ARE QUITE MIXED...WITH MET GUIDANCE SHOWING 25 DEGREES AT GRAND
JUNCTION. THE TIMING OF THE CLEARING WILL BE IMPORTANT BEHIND
SUNDAY/S COLD FRONT.

DRIER CONDITIONS FOLLOW ON MONDAY...WITH WARMING ON TUESDAY. THE
NEXT WAVE IS SCHEDULED FOR WEDNESDAY. HOWEVER EACH MODEL RUN
TRACKS THIS SYSTEM ON A MORE NORTHERLY PATH...KEEPING US MOSTLY
DRY...BUT POSSIBLY WINDY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1143 AM MDT FRI APR 11 2014

VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD WITH TYPICAL
DIURNAL WIND CYCLE. UPVALLEY WINDS WILL GUST 20-25KT THIS AFTN BUT
DROP OFF WITH SUNSET. MID AND HIGH LEVEL CLOUDS WILL INCREASE
OVERNIGHT. ISOL SHOWERS AND MTN OBSCURATIONS ARE POSSIBLE OVER
THE HIGHER TERRAIN BY MID TO LATE MORNING SATURDAY.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
     EVENING FOR COZ004-009-010-012-013.

UT...NONE.
&&

$$

SHORT TERM...EH
LONG TERM...BEN
AVIATION...BEN



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