Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 271139
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
439 AM MST FRI FEB 27 2015

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 437 AM MST FRI FEB 27 2015

H5 VORT MAX OVER EASTERN UTAH THIS MORNING HAS INITIATED SOME
LIGHT SNOW SHOWERS FROM LOW STRATUS ALONG THE I-70 CORRIDOR. THIS
LINE OF SHOWERS IS MOVING TO THE SOUTHEAST AND IS AHEAD OF THE
BIGGER MOISTURE SOURCE AND ENERGY WHICH WILL MOVE INTO THE REGION
THIS AFTERNOON. THE SHOWERS THIS MORNING WILL NOT COMPLETELY MOVE
OUT OF EASTERN UTAH AND WESTERN COLORADO TODAY BUT SLOWLY
PROGRESS SOUTH AND EAST THROUGH THE EARLY AFTERNOON.

AN UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST WILL DROP SOUTH
TODAY ALONG THE CALIFORNIA COAST AND OPEN THE PACIFIC MOISTURE TAP
FROM THE WEST. SPECIFIC HUMIDITY VALUES PROGRESSIVELY INCREASE
OVER THE NEXT 36 HOURS...ESPECIALLY OVER THE FOUR CORNERS WHERE
VALUES ARE PROGGED TO REACH 4 G/KG OVER THE SOUTHERN COLORADO
VALLEYS BY SATURDAY EVENING. AS THIS TROUGH REACHES CENTRAL
CALIFORNIA BY SATURDAY AFTERNOON...A LOW CLOSES OFF AND LEAVES THE
GREAT BASIN IN WEST SOUTHWESTERLY FLOW WHICH WILL STREAM ENERGY
AND MOISTURE INTO EASTERN UT AND WESTERN CO OVER THE NEXT FEW
DAYS. THE FIRST BOUT OF HEAVY SNOW WILL BE TONIGHT OVER THE FOUR
CORNERS AREA. SHOWERS WILL BECOME MORE WIDESPREAD FROM SOUTHWEST
TO NORTHEAST ON SATURDAY AS THE TROUGH ELONGATES ACROSS THE
REGION.

KEPT ISO TSTORMS IN FOR LARGE SWATH OF EASTERN UT AND WESTERN CO
FOR THIS AFTERNOON AND SATURDAY AFTERNOON WITH INSTABILITY AND
STEEP LAPSE RATES IN PLACE AHEAD OF THE LOW PRESSURE CENTER. NOT
EXPECTING WIDESPREAD LIGHTNING BUT A FEW STRIKES ARE DEFINITELY
POSSIBLE OVER THE NEXT COUPLE OF DAYS.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 437 AM MST FRI FEB 27 2015

MODELS REMAIN IN EXCELLENT AGREEMENT FOR THE NEXT STORM WITH
COPIOUS AMOUNTS OF SNOWFALL FOR THE SRN MTNS AND TO A LESSER
EXTENT THE CENTRAL MTNS. BY COPIOUS...WE`RE TALKING ANYWHERE FROM
3 TO 4 FEET OF SNOW...A REMARKABLE AMOUNT THAT CERTAINLY LOOKS
REASONABLE.

STARTING SATURDAY NIGHT...THE JET STREAM WILL HAVE ROUNDED AN
UPPER LEVEL TROUGH LOCATED OVER THE GREAT BASIN AND WILL LIE
DIRECTLY ACROSS SERN UT AND COLORADO. THE LOCATION OF THE JET WILL
ALSO ALLOW PACIFIC MOISTURE TO STREAM UP FROM THE SOUTHWEST. THIS
JET STAYS OVER US THROUGH TUESDAY UNTIL SHIFTING EAST WHICH WILL
KEEP MOISTURE IN PLAY FOR MUCH OF THE PERIOD. GFS SHOWS WHAT LOOKS
LIKE THREE FAIRLY DISTINCT WAVES WITH THE FIRST MOVING OVERHEAD
SATURDAY NIGHT THROUGH SUNDAY MORNING. THE SECOND WAVE...ALSO THE
STRONGEST...IS PROGGED TO MOVE OVER SUNDAY NIGHT THROUGH MONDAY
NIGHT AND THE FINAL WAVE WILL MOVE ACROSS THE REGION TUESDAY
MORNING THROUGH WEDNESDAY MORNING. THE SECOND WAVE WILL LIKELY
PRODUCE SNOWFALL RATES EASILY OVER AN INCH AN HOUR FOR THE SAN
JUANS WHERE AGAIN...3 TO 4 FEET OF SNOWFALL CAN`T BE RULED OUT.
THE CENTRAL MTNS WILL LIKELY SEE 1 TO 2 FEET OF SNOW WITH SOUTH
FACING SLOPES BEING FAVORED. DECIDED TO INCLUDE ZONE 10 TO GOING
WARNINGS STARTING SATURDAY MORNING AS THE SECOND WAVE MOVES
OVERHEAD. NRN MTNS MAY ALSO SEE SOME ACCUMULATION BUT SW FLOW DOES
NOT FAVOR THAT AREA SO MAYBE 8 TO 12 INCHES THERE. DID NOT RAISE
ANY HIGHLIGHTS FOR AREAS ALONG AND NORTH OF I-70 TO ALLOW A FEW
MORE MODEL RUNS TO GET THE FINER DETAILS THERE. IMPORTANT TO
MENTION THAT THROUGH THIS ENTIRE PERIOD...SATURDAY NIGHT THROUGH
WEDNESDAY MORNING...THERE WILL BE LULLS IN PRECIPITATION AS ONE
WAVE MOVES OFF AND ANOTHER APPROACHES. THE `LUCKY` AREAS...THINK
WOLF CREEK PASS...MAY SEE CONTINUOUS SNOW THROUGH THE ENTIRE
PERIOD.

AS FAR AS SRN VALLEYS ARE CONCERNED...TEMPS WILL BE HOVERING NEAR
FREEZING BUT STILL EXPECT PLENTY OF SNOW FOR THOSE AREAS THOUGH
THERE MAY BE A RAIN/SNOW MIX AT TIMES. MODEL GUIDANCE STILL
SUGGESTING TOO WARM FOR ACCUMULATING SNOW FOR SERN UT AND ALSO THE
PARADOX VALLEY/LOWER DOLORES RIVER AREAS. OF COURSE...THE LAST
STORM LOOKED TOO WARM FOR THOSE AREAS AND ENDED UP DROPPING ABOUT
A FOOT OF SNOW SO THE POSSIBILITY DOES EXIST.

IF TRAVELLING THIS WEEKEND...ESPECIALLY OVER ANY MTN
PASSES...PLEASE PAY PARTICULAR ATTENTION TO THE LATEST WEATHER
FORECAST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 437 AM MST FRI FEB 27 2015

MANY SITES REPORTING IFR TO MVFR THIS MORNING AS SNOW...FOG...AND
LOW CIGS MOVE ACROSS THE AREA. A BREAK IS EXPECTED TODAY BEFORE
PRECIP INCREASES FROM THE SOUTH AFTER 00Z. EVEN SO...OCCNL
MVFR/IFR IS STILL POSSIBLE THROUGH THE DAY AS WEAK BANDS OF PRECIP
PERSIST. AFTER 00Z...FLIGHT CONDITIONS WILL DETERIORATE FROM
SOUTH TO NORTH DROPPING STEADILY. THESE CONDITIONS WILL PERSIST
FOR QUITE SOME TIME. MTNS WILL BE OBSCURED TODAY AND INTO THE
WEEKEND.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 8 PM MST
     MONDAY FOR COZ014-021.

     WINTER STORM WARNING FROM NOON TODAY TO 8 PM MST MONDAY FOR
     COZ009-012-017>019.

     WINTER WEATHER ADVISORY UNTIL 8 AM MST THIS MORNING FOR COZ008.

     WINTER STORM WARNING FROM 6 PM THIS EVENING TO 8 PM MST MONDAY
     FOR COZ022-023.

     WINTER STORM WARNING FROM 11 AM SATURDAY TO 8 PM MST MONDAY FOR
     COZ010.

UT...WINTER STORM WARNING FROM NOON TODAY TO 8 PM MST MONDAY FOR
     UTZ028.

&&

$$

SHORT TERM...JAM
LONG TERM...TGR
AVIATION...TGR


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