Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 022006
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
106 PM MST MON MAR 2 2015

.UPDATE...
ISSUED AT 105 PM MST MON MAR 2 2015

HAVE UPDATED THE FORECAST FOR HIGHER TEMPERATURES THIS AFTERNOON.
OBSERVATIONS HAVE ALREADY SURPASSED THE FORECAST HIGHS AT MANY
LOCATIONS. THIS ALSO HAS RAMIFICATIONS ON SNOW LEVELS WHICH WILL
BE ON THE HIGH SIDE THIS AFTERNOON AND EARLY THIS EVENING IN THE
PREFRONTAL ENVIRONMENT. ON THE FLIP SIDE IS THAT THE AIR MASS IS
BECOMING MORE UNSTABLE AS THE FRONT APPROACHES... WHICH WILL PUSH
SNOW LEVEL MUCH LOWER IN ANY CONVECTIVE SHOWERS THAT DEVELOP. WILL
LEAVE THE HIGHLIGHTS UP FOR THE NORTHERN VALLEYS WHERE
PRECIPITATION TYPE MAY BE PREDOMINANTLY RAIN FOR A FEW MORE
HOURS...BEFORE SWITCHING TO ALL SNOW DURING THE EARLY TO MID
EVENING HOURS. ALSO 4 INCHES OF SNOW HAS BEEN REPORTED IN VERNAL
BY THE PUBLIC. THERE SEEMS TO BE SOME COLDER AIR TRAPPED IN THAT
VALLEY...WHERE THE TEMPERATURE CONTINUE TO BE JUST A FEW DEGREES
ABOVE FREEZING. HOWEVER...ROADS REMAIN CLEAR AND WEB CANS INDICATE
GOOD SETTLING...SO WILL NOT HOIST ANYTHING AT THIS TIME. WILL
CONTINUE TO ASSESS FOR THE AFTERNOON PACKAGE THOUGH.

UPDATE ISSUED AT 1111 AM MST MON MAR 2 2015

SURFACE TEMPERATURES ACROSS NORTHWEST COLORADO HAVE INCREASED
ENOUGH SO THAT FREEZING RAIN IS NO LONGER EXPECTED. AT 11AM RAIN
WAS REPORTED AT CRAIG AND MEEKER. HOWEVER WILL KEEP THE WINTER
HIGHLIGHTS FOR CO ZONES 1 AND 2 SINCE PRECIPITATION SHOULD CHANGE
TO...OR MIX WITH SNOW AT TIMES THIS AFTERNOON AS CONVECTION
PUSHES THE SNOW LEVELS LOWER. THEN BY MID EVENING...ALL SNOW IS
EXPECTED DUE TO NIGHTTIME COOLING AND ESPECIALLY THE FRONTAL
PASSAGE WHICH LOOKS TO OCCUR BETWEEN 5PM AND 8PM MST PER THE NAM
12 SOUNDING. OTHERWISE THE CURRENT FORECAST LOOKS ON TRACK EXCEPT
FOR A FEW MINOR ADJUSTMENTS.

UPDATE ISSUED AT 821 AM MST MON MAR 2 2015

RECEIVED SOME REPORTS OF PATCHY FREEZING RAIN IN AND AROUND THE
MEEKER AREA WITH A FEW ACCIDENTS BEING REPORTED BY THE SHERIFFS
DEPARTMENT. EXAMINATION OF THE SKEW-T DOES SHOW WARMER AIR ALOFT
WITH PRECIP FALLING INTO COOLER SFC TEMPS SO FREEZING RAIN LOOKS
POSSIBLE. DO ANTICIPATE VERY PATCHY FREEZING RAIN SO ISSUED
ADVISORY FOR NORTHERN ZONES THROUGH NOON WITH GOOD CHANCE IT WILL
COME DOWN EARLY AS TEMPS MODIFY. NO OTHER CHANGES AT THIS TIME.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 502 AM MST MON MAR 2 2015

IN THE UPPER ATMOSPHERE THIS MORNING THE COLDER NORTHERN TROUGH
WAS BEGINNING TO PHASE WITH THE CALIFORNIA LOW THAT WILL BEGIN ITS
PUSH EASTWARD. THIS WILL TIGHTEN THE GRADIENT THROUGH THE
ATMOSPHERE WITH THE JET INCREASING FROM 120KT TO AN IMPRESSIVE
150KT OVER THE CENTRAL FORECAST AREA THIS AFTERNOON.

AT THE SURFACE A WARM FRONT SLOWLY LIFTED INTO NE UTAH- NW
COLORADO OVERNIGHT AND HAS STALLED THERE UNTIL IT IS OVERRUN BY
THE COLD AIR MASS THIS AFTERNOON. THE SURFACE LOW UNDERNEATH THE
STRENGTHENING JET LIFTS INTO SE UTAH BY MIDDAY AND INTO NW CO IN
THE AFTERNOON DEEPENING AS IT GOES. 700MB WINDS OF 45KTS MAY BE
MIXED DOWN INTO THE VALLEYS AT TIMES NEAR THE FRONT. COORDINATED
WITH SLC FGZ ABQ FOR POTENTIAL WIND HIGHLIGHTS. BUT A SATURATED
BOUNDARY LAYER WOULD LIMIT GUST POTENTIAL. THE STRONGEST WINDS
ARE EXPECTED OVER HIGHER TERRAIN WITHIN THE EXISTING WINTER STORM
WARNINGS.

SNOW SOUTH OF I-70 WILL BE MORE OROGRAPHICALLY DRIVEN THIS
MORNING FAVORING SW-FACING SLOPES WITH BETTER ACCUMULATIONS ACROSS
THE NORTH. A RAIN SNOW MIX IS EXPECTED IN THE NORTHERN VALLEYS
THIS MORNING LIMITING ACCUMULATIONS. SNOW LEVELS IN THE SOUTH
WILL BE AROUND 8000FT UNTIL FRONTAL PASSAGE.

COLD AIR POURS IN TONIGHT THROUGH TUESDAY. SNOW LEVELS LOWER TO
VALLEY BOTTOMS AFTER MIDNIGHT TONIGHT. DYNAMICAL SUPPORT ENDS AS
THE JET LIFTS NE ON TUESDAY...BUT STRONG COLD ADVECTION WILL
CONTINUE TO BRING OROGRAPHIC SNOWFALL TO WEST AND NW-FACING
SLOPES. THE NEW AIR MASS WILL CONSIDERABLY DRIER AND SNOW WILL
BECOME MUCH LESS DENSE EVOLVING TO 15:1 OR 20:1 BY LATE TUESDAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 502 AM MST MON MAR 2 2015

THE LAST SIGNIFICANT TROUGH OF THIS SERIES OF SYSTEMS WILL TRAVEL
OVER THE AREA FROM NW TO SE TUE NIGHT...WITH MUCH DRIER AND COOLER
AIR MOVING IN BEHIND IT WED AND THU. A MINOR DISTURBANCE FROM THE
NW WILL MOVE THROUGH THU AND FRI EVENING...BUT THIS SHOULD PRODUCE
ONLY ISOLATED OROGRAPHIC SNOWFALL IN THE NORTHERN MOUNTAINS.

WENT BELOW GUIDANCE FOR MAX AND MIN TEMPS TUE THROUGH THU NIGHT AS
THE COOLER THAN NORMAL CONDITIONS WILL CONTINUE. A STRONG RIDGE
WILL DEVELOP OVER THE WESTERN U.S FRIDAY THROUGH THE WEEKEND...
WHICH WILL ALLOW A WARMING TREND THROUGH THE WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1029 AM MST MON MAR 2 2015

SCATTERED SHOWERS THIS MORNING FROM I-70 SOUTH WILL BECOME
NUMEROUS THIS AFTERNOON AS A COLD FRONT SWEEPS THE REGION. NORTH
OF I-70 SHOWERS WILL BE WIDESPREAD THROUGH THE DAY. RAIN/SNOW
LINE VARIES FROM 8000FT SOUTH TO 6500 NORTH. CIGS WILL TREND
LOWER WITH VFR BECOMING MVFR.

LOW LEVEL WIND SHEAR POSSIBLE ACROSS THE FORECAST AREA THIS
MORNING THAT WILL MIX DOWN THIS AFTERNOON. WIDESPREAD G25KT WITH
MORE LOCALIZED G40KT POSSIBLE EVEN INTO THE VALLEYS AS THE COLD
FRONT PASSES. MODERATE TO STRONG MECHANICAL TURBULENCE WILL OCCUR
WITH THE FRONT TIMED AT 18Z-21Z IN EASTERN UTAH TO 21-02Z ACROSS
WESTERN COLORADO. DURING THE FRONTAL PASSAGE...ALL TAF SITES WILL
HAVE VIS BLO 3SM BR IN RAIN OR SNOW (SNOW LEVEL LOWERING TO NEAR
THE VALLEY FLOORS) WITH CIGS BELOW ILS BREAKPOINTS.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL 5 PM MST TUESDAY FOR COZ001-002-009-
     010-012-017>019.

     WINTER STORM WARNING UNTIL 9 AM MST WEDNESDAY FOR COZ003>005-013.

UT...WINTER STORM WARNING UNTIL 5 PM MST TUESDAY FOR UTZ023-025-028.

&&

$$

UPDATE...EH
SHORT TERM...JOE
LONG TERM...CC
AVIATION...TGJT


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