Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 260546
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1046 PM MST WED FEB 25 2015

.UPDATE...
ISSUED AT 646 PM MST WED FEB 25 2015

SCATTERED SNOW SHOWERS HAVE BEEN SPILLING INTO THE WEST CENTRAL
VALLEYS. HRRR MODEL SHOWING SNOW SHOWER ACTIVITY MOVING INTO
MONTROSE LATER THIS EVENING. BOOSTED VALLEY POPS THIS EVENING TO
REFLECT CURRENT SHORT TERM TRENDS.

&&

.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 330 PM MST WED FEB 25 2015

MOIST...UNSTABLE CONDITIONS HAVE KEPT SNOW SHOWERS GOING ALL DAY
ACROSS WESTERN COLORADO AND THIS WILL CONTINUE INTO THE LATE
EVENING HOURS. THE COOL ADVECTIVE NORTHWEST FLOW IS FAVORING MANY
NORTH AND WEST FACING ASPECTS FROM THE FLAT TOPS AND NORTHERN
PLATEAUS TO THE NORTHERN SAN JUANS. WEBCAMS SHOW THE INTENSITY OF
THE CONVECTIVE SNOW SHOWERS WITH VISIBILITIES DROPPING QUICKLY AS
SNOW RATES INCREASE. HOWEVER LOOKING AT AREA WEB CAMS ROADWAYS ARE
STAYING IN FAIRLY GOOD SHAPE...EVEN OVER THE HIGHER PASSES.
SNOTELS HAVE PICKED UP THIS AFTERNOON WITH THE ADDED OCTANE BUT
STILL THE MAJORITY ARE IN THE 2 TO 4 INCH RANGE. SNOW STAKES SHOW
THE SAME AT LOCAL SKI AREAS. WATER VAPOR IMAGERY INDICATES THE
WAVE DRIVING THESE SHOWERS IS DROPPING ACROSS SOUTHWEST WYOMING
LATE THIS AFTERNOON AND WILL BE SHEARING ACROSS THE COLORADO UTAH
BORDER THROUGH THE EVENING. THOUGH SOME BOOST WILL BE LOST AT
SUNSET SHOWERS SHOULD CONTINUE ACROSS THE CENTRAL AND SOUTHERN
MOUNTAINS THROUGH LATE EVENING...ENDING OVERNIGHT. SOME SHOWERS
ARE LIKELY TO LEAK INTO THE LOWER VALLEYS OF WESTERN COLORADO
ALONG I-70 AND NORTHWARD AS WELL BUT LITTLE ACCUMULATION IS
EXPECTED. SUBSIDENCE AND INCREASING STABILITY IN THE TRANSITION
AREA BETWEEN THE DEPARTING WAVE AND THE NEXT ENERGY DIGGING TO OUR
WEST LOOKS TO BRING A RATHER SIGNIFICANT BREAK THURSDAY MORNING
FOR OUR CWA. LIGHT OROGRAPHIC SNOW SHOWERS COULD REMAIN OVER THE
DIVIDE MOUNTAINS OVER THE NEXT 24 HOURS AS DENDRITIC TEMPERATURES
AT MOUNTAIN TOP LEVEL WILL BE IN THE SWEET SPOT. ADDITIONAL LIGHT
ACCUMULATIONS WILL BE POSSIBLE BUT SNOW RATES NOT EXCESSIVE. HIGH
LEVEL MOISTURE WILL BEGIN TO MAKE IT/S WAY BACK INTO THE GREAT
BASIN THROUGH THE DAY AS ANOTHER UPSTREAM WAVE MOVES THROUGH THE
NORTHWEST FLOW INTO THE GREAT BASIN. INSTABILITY WILL BE PRESENT
BUT NOT QUITE AS ROBUST AS THIS AFTERNOON AND JET SUPPORT RETREATS
TO THE WEST. EXPECT INCREASING POPS MAINLY ON THE TERRAIN ON
THURSDAY AFTERNOON WITH SOME DECREASE IN ACTIVITY AT SUNSET.
THURSDAY NIGHT THE WAVE TAKES A TIGHTER CYCLONIC CURVE ACROSS THE
4 CORNERS AS THE UPPER JET BEGINS TO CURVE ALOFT. THIS WILL LIKELY
KEEP SOME SNOW GOING IN THE HILLS FAVORING THE SOUTHERN CWA
THROUGH THE NIGHT BUT AGAIN ONLY LIGHT ACCUMULATIONS ARE EXPECTED.
UPSTREAM ACROSS THE LEFT COAST FROM SO.CAL NORTHWARD...300K
SURFACES SHOW A HEALTHY SURGE OF PACIFIC MOISTURE BEING
TRANSPORTED INLAND AS OUR WEATHER MAKER FOR THE WEEKEND DROPS
ACROSS THE PACIFIC NORTHWEST.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 330 PM MST WED FEB 25 2015

WELCOME TO WEEKEND STORM NUMBER TWO UNDER THIS NEW IMPROVED
WEATHER PATTERN. THIS STORM IS NOTABLE FOR ITS EXTENDED PERIOD OF
PERSISTENT SHOWERS...PERHAPS THROUGH NEXT WEDNESDAY.

THE FIRST OF TWO PACIFIC TROUGHS SLIDES DOWN THE WEST COAST
EVENTUALLY CLOSING OFF ALONG THE SOUTHERN CALIFORNIA COAST BY
SUNDAY. DESCENT MOISTURE AND GOOD OROGRAPHICS WITH PERIODS OF
UPPER LEVEL SUPPORT SHOULD PRODUCE GOOD SNOWFALL FROM THE FOUR
CORNERS NE TO THE WEST ELK MOUNTAINS. A WINTER STORM WATCH HAS
BEEN ISSUED FOR THESE ZONES.

FRIDAY-FRIDAY NIGHT...IN MILD WARM MOIST ADVECTION...SHOWERS WILL
INCREASE ACROSS THE SOUTH. OROGRAPHICS WILL FAVOR SW-FACING
SLOPES.

SATURDAY-SATURDAY NIGHT THE PATTERN AMPLIFIES AS THE LOW DIGS
DOWN THE COAST. THE 120KT JET OVER NEW MEXICO LIFTS ACROSS THE SAN
JUAN MTNS INTO THE WEST ELKS. 700MB WINDS INCREASE TO 40KTS UNDER
THE JET. A SURFACE-700MB LOW DEEPENS IN SE UTAH ADDING TO THE
OROGRAPHIC COMPONENT INTO THE SOUTHERN MOUNTAIN SLOPES. 700MB
TEMPERATURES AROUND -4C WOULD PRODUCE AFTERNOON SNOW LEVELS
AROUND 7KFT. THE JET SHIFTS EAST ON SUNDAY FOR SOME DIMINISHING OF
THE MOUNTAIN WINDS BUT MOIST OROGRAPHIC SNOW REMAINS IN PLACE.

FOR MONDAY THE 18Z GFS HAS SLOWED DOWN TO MATCH THE EC TIMING WITH
THE PROGRESSION OF THIS FIRST LOW OFF TO THE SE. THE SFC LOW
LIFTS THROUGH THE SOUTH THRU THE DAY. A DOWN TURN OF SHOWERS IS
EXPECTED MONDAY NIGHT AND WE HAVE ENDED THE WINTER STORM WATCH
HERE.

BUT ALREADY BY TUESDAY A COLDER TROUGH HAS DIVED DOWN THE COAST
SETTLING OVER THE GREAT BASIN. A STRONG COLD FRONT PASSES ON
TUESDAY DRIVING SNOW LEVELS TO THE LOWEST ELEVATIONS AND
EFFICIENTLY TURNING ANY AVAILABLE MOISTURE TO SNOW. TUESDAY NIGHT
INTO WEDNESDAY THE FLOW TURNS TO COLD ADVECTIVE NORTH WITH SNOW
LINGERING ALONG THE NORTH-FACING SLOPES BUT STILL FAVORING THE
SOUTH WHERE MOISTURE IS DEEPEST. HIGHLIGHTS ARE EXPECTED WITH THIS
SECOND LOW ALSO.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1042 PM MST WED FEB 25 2015

SCATTERED SHOWERS CONTINUE ACROSS WEST CENTRAL COLORADO AND THE
SOUTHWESTERN COLORADO MOUNTAINS. SHOWERS ARE EXPECTED TO TAPER OFF
BY 12Z THURSDAY MORNING. VFR CONDITIONS EXPECTED BETWEEN 12Z AND
18Z THURSDAY...BUT MORE SNOW WILL DEVELOP OVER WESTERN COLORADO
(MAINLY IN THE MOUNTAINS) AFTER 18Z INCLUDING KASE...KEGE...AND
KTEX. ALL TAF SITES HAVE A CHANCE OF RECEIVING PRECIPITATION AFTER
00Z THURSDAY EVENING.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WATCH FROM FRIDAY MORNING THROUGH MONDAY EVENING
     FOR COZ012-014-018-019-022-023.

UT...NONE.
&&

$$

UPDATE...PF
SHORT TERM...15
LONG TERM...JOE
AVIATION...JAM



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