Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 301130
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
430 AM MST FRI JAN 30 2015

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 430 AM MST FRI JAN 30 2015

SURFACE OBSERVATIONS...WEB CAMS AND THE CHAIN LAW ON HIGHWAY 550
OVER THE SAN JUANS INDICATE THAT SNOW HAS BEEN ACCUMULATING OVER
THE SOUTHERN MOUNTAINS SINCE LAST EVENING AND THROUGH EARLY THIS
MORNING. DEEP MOISTURE HAS BEEN INVADING FROM THE SOUTH AND
SATELLITE IMAGES SHOW ITS SOURCE ORIGINATING IN THE TROPICAL
PACIFIC NEAR 10-15 DEGREES NORTH AND ROUGHLY AROUND 110 DEGREES
WEST. A LOW PRESSURE SYSTEM OFF THE COAST OF SOUTHERN CA/BAJA HAS
BEEN RESPONSIBLE FOR PUMPING THIS MOISTURE INTO THE REGION. AND AS
THE LOW SHIFTS INTO SOUTHERN CALIFORNIA TODAY...AND THEN OVER THE
NORTHERN SEA OF CORTEZ ON SATURDAY ABUNDANT MOISTURE WILL CONTINUE
OVER THE AREA. ISENTROPIC UPGLIDE OVER THE REGION HAS PROVIDED
SYNOPTIC SCALE LIFT WHICH WILL CONTINUE THROUGH TODAY...THEN
WEAKEN OVERNIGHT. THEN DURING THE DAY ON SATURDAY THE FLOW
GRADUALLY SWITCHES AROUND AS THE NORTHERN STREAM BECOMES MORE OF
A PLAYER FOR OUR AREA. A WAVE IS PROGGED TO DROP INTO MONTANA...
AND THE SOUTHERN LOW SLOWLY SHIFTS TO THE SOUTH-SOUTHEAST.
THROUGH THIS EVENT THE SOUTHERN PORTION OF THE FORECAST AREA WILL
BE FAVORED...BUT REALLY THE BEST ACTIVITY WILL STAY TO OUR SOUTH
OVER ARIZONA AND NEW MEXICO.

FOR TODAY...PRECIPITATION WILL CONTINUE TO INCREASE AND SPREAD
NORTH AS THE DEEPER MOISTURE PROGRESSES FROM SOUTH TO NORTH.
HOWEVER DUE TO THE TROPICAL ORIGIN OF THE AIR MASS...SNOW LEVELS
WILL STAY ON THE HIGH SIDE. IT APPEARS THAT THE SNOW LEVEL IS
AROUND 7000-7500 FEET EARLY THIS MORNING WITH SNOW REPORTED IN
PAGOSA SPRINGS...BUT RAIN IN DURANGO. EXPECT THE SNOW LEVELS WILL
RISE TODAY...BEFORE FALLING AGAIN TONIGHT. HOWEVER THERE JUST IS
NOT MUCH COOLING INDICATED THROUGH SATURDAY...SO SNOW LEVELS WILL
AGAIN RISE ON SATURDAY. GOOD PRECIPITATION WILL CONTINUE INTO
SATURDAY...GRADUALLY WINDING DOWN SOMEWHAT DURING THE AFTERNOON
AS A DRIER NORTHWEST FLOW MOVES DEVELOPS.

WENT AHEAD AND STARTED THE SNOW ADVISORIES FOR THE SOUTHERN
MOUNTAINS EARLIER SINCE SNOW HAD ALREADY STARTED ACCUMULATING.
OTHERWISE NO CHANGES IN THE COVERAGE. HOWEVER OTHER MOUNTAIN
AREAS THAT BEAR WATCHING INCLUDE THE GRAND MESA AND POSSIBLE THE
WEST ELKS.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 430 AM MST FRI JAN 30 2015

PRECIPITATION DIMINISHES SATURDAY NIGHT AS THE CLOSED LOW DRIFTS
SOUTHWARD IN RESPONSE TO A SHORTWAVE TROUGH SWEEPING SOUTHEASTWARD
ACROSS THE NORTHERN ROCKIES. QUIET...DRY WEATHER RETURNS SUNDAY
WITH TEMPERATURES RUNNING A BIT ABOVE NORMAL.

HOWEVER...BY LATE SUNDAY NIGHT...THE FIRST OF A SERIES OF SHORT
WAVE TROUGHS IN NORTHWEST FLOW WILL BEGIN TO GENERATE SNOW OVER
THE NORTHERN MOUNTAINS. MODELS WERE CONSISTENT IN DEPICTING SNOW
CONTINUING OFF AND ON OVER THE NORTHERN...AND PORTIONS OF THE
CENTRAL COLORADO MOUNTAINS...THROUGH MIDWEEK BEFORE THE RIDGE
OVER THE WEST FINALLY AMPLIFIES FORCING THE POLAR JET TO THE EAST.
ACCUMULATIONS NOT VERY IMPRESSIVE ACCORDING TO MODEL DATA...BUT
WILL HAVE TO MONITOR FOR POSSIBLE HIGHLIGHTS EARLY NEXT WEEK.

TEMPERATURES WILL CONTINUE TO MODERATE WITH READINGS RISING TO
LEVELS OF AROUND 10 DEGREES ABOVE NORMAL BY EARLY NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 430 AM MST FRI JAN 30 2015

A PACIFIC STORM TO THE SOUTHWEST WILL CONTINUE TO BRING
PRECIPITATION TO MUCH OF THE REGION DURING THE NEXT 24 HOURS.
GIVEN THE WARM NATURE OF THIS SYSTEM...SNOW LEVELS WILL HOVER
RIGHT AROUND THE 7500 FOOT MARK THROUGH THE PERIOD. AS A
RESULT...KDRO WILL CONTINUE TO EXPERIENCE RAIN OFF AND ON THROUGH
SATURDAY MORNING WITH MVFR CIGS AND VSBY. MEANWHILE...THE SOUTHERN
MOUNTAINS WILL FREQUENTLY BE OBSCURED DUE TO CLOUDS AND SNOW.
THERE IS A GOOD CHANCE THAT THE TAF SITES ALONG THE I-70 CORRIDOR
AS WELL AS A KMTJ FACE A GOOD CHANCE FOR RAIN SHOWERS THROUGHOUT
THE DAY WITH BETTER CHANCES TONIGHT. EXCEPT FOR KASE...
PRECIPITATION TYPE IS LIKELY TO BE RAIN. AS FOR KVEL...
PRECIPITATION CHANCES ARE SLIGHT GIVEN DISTANCE FROM THE STORM/S
CENTER.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 8 PM MST SATURDAY FOR COZ017>019.

UT...WINTER WEATHER ADVISORY UNTIL 8 PM MST SATURDAY FOR UTZ028.

&&

$$

SHORT TERM...EH
LONG TERM...NL
AVIATION...NL


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