Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 251752
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1052 AM MST WED FEB 25 2015

.UPDATE...
ISSUED AT 1037 AM MST WED FEB 25 2015

ROBUST SHORTWAVE MOVING WESTERN COLORADO THIS MORNING BRINGING
SOME WIDESPREAD LIGHT SNOW SHOWERS WEST OF A TEX TO GJT TO VEL
LINE. SNOW IS MAKING IT TO THE NORTHERN VALLEYS FROM CRAIG
EASTWARD WITH A CONVERGENT LINE ALSO BRINGING SHOWERS OFF THE ROAN
PLATEAU TO THE RIFLE UP TO THE GLENWOOD SPRINGS AREA. SNOTELS NOT
SHOWING MUCH ACCUMULATION ATTM AND ROADWAYS ALL SEEM TO BE IN GOOD
SHAPE SO STILL NO PLANS FOR WINTER HEADLINES ATTM. OVERALL RAISED
POPS IN SOME AREAS INCLUDING THE NORTH FACING SAN JUANS WHERE
OURAY AND TEX ALL SHOWING SNOW. HAVE ALSO ADJUSTED SOME HIGH
TEMPERATURES ASSOCIATED WITH THE PRECIP AND CLOUD COVER.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM MST WED FEB 25 2015

UNSETTLED NORTHWEST FLOW WILL CONTINUE OVER THE NEXT COUPLE OF
DAYS WITH AN UNORGANIZED WEATHER DISTURBANCE AFFECTING
NORTHWESTERN COLORADO TODAY. THE BULK OF THIS SYSTEM WILL HEAVILY
OCCUR ON THE FRONT RANGE...BUT FORECAST H5 VORTICITY FIELDS PUSH
PULSES OF ENERGY THROUGH WESTERN COLORADO AS WELL TODAY. SATELLITE
IMAGERY NOT VERY IMPRESSIVE WITH THIS SYSTEM THOUGH CLOUD TOPS ARE
BEGINNING TO INCREASE OVER NORTHERN UTAH. WX MODELS THIS MORNING
NOT SUPPORTING SUBSTANTIAL SNOW IN THE NORTHCENTRAL COLORADO
MOUNTAINS BUT COULD POTENTIALLY SEE 5 INCHES IN ISOLATED HIGH
ELEVATIONS SPOTS OF THE NORTH CENTRAL MOUNTAINS. WILL CONTINUE
WITHOUT ANY HILIGHTS THIS MORNING WITH SUB-ADVISORY AMOUNTS
EXPECTED. EXPECT AN UPTICK IN ACTIVITY LATE THIS AFTERNOON AS THE
MAIN PUSH OF ENERGY MOVES THROUGH FROM THE NORTHWEST AND INSTABILITY
INCREASES. CONVECTIVE SHOWERS ARE LIKELY TO DEVELOP THIS
AFTERNOON SO NUDGED POPS UP FROM MODEL OUTPUT TO ACCOUNT FOR
SLIGHT CHANCE OF SHOWERS ACROSS A BROADER AREA.

A SHORT BREAK IN THE WEATHER LOOKS LIKELY THURSDAY MORNING BEFORE
A TROUGH AT THE 700MB LEVEL DROPS INTO THE EASTERN GREAT BASIN IN
THE AFTERNOON. THINKING THAT THE GFS/EC/SREF ARE A BIT TOO BROAD
WITH THEIR PRECIPITATION AND THAT THE NAM SOLUTION WHICH LOOKS
RATHER CONVECTIVE IS MORE LIKELY FOR THURSDAY AFTERNOON.

TEMPERATURES WILL REMAIN BELOW NORMAL OVER THE NEXT COUPLE OF DAYS
DUE TO COOL NORTHWEST FLOW.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 355 AM MST WED FEB 25 2015

THE SHORT WAVE TROUGH DESCRIBED ABOVE WILL CONTINUE TO SWEEP
ACROSS THE SOUTHERN HALF OF THE FORECAST AREA THURSDAY EVENING
THEN PUSH OFF TO THE EAST LATER IN THE NIGHT. MEANWHILE...A
SECOND SHORT WAVE TROUGH MOVES ACROSS NORTHEAST UTAH AND NORTHWEST
COLORADO DURING THE NIGHT. MODELS INDICATED INSTABILITY AND
OROGRAPHIC LIFT SHOULD KEEP SCATTERED SNOW SHOWERS GOING FRIDAY.
SNOWFALL FROM THESE DISTURBANCES WILL MAINLY IMPACT THE MOUNTAINS.
MOISTURE DEPTH NOT ALL THAT IMPRESSIVE SO ACCUMULATIONS EXPECTED
TO BE RELATIVELY LIGHT AND THEREFORE DO NOT ANTICIPATE HIGHLIGHTS
DURING THIS PERIOD.

IT APPEARS THIS WEEKEND WILL BE ANOTHER MATTER. THE LATEST MODELS
CONTINUED TO DEPICT A PATTERN NOT ENTIRELY DISSIMILAR TO THAT
ASSOCIATED WITH THE STORM WHICH DUMPED SIGNIFICANT SNOWFALL
ACROSS SOUTHEAST UTAH AND SOUTHWEST COLORADO THIS PAST WEEKEND.
SPECIFICALLY...MODELS SHOWED A LOW OVER THE PACIFIC NORTHWEST
DIGGING SOUTHWARD ACROSS THE GREAT BASIN TO NEAR SOUTHERN
CALIFORNIA THIS WEEKEND. AS THE PATTERN EVOLVES PACIFIC MOISTURE
BECOMES ENTRAINED CAUSING 7H SPECIFIC HUMIDITY TO RISE TO THE 3.5
TO 4.0 G/KG RANGE. THE COMBINATION OF DEEP MOISTURE...LARGE SCALE
ASCENT...AND OROGRAPHIC FLOW INTO THE SOUTHERN MOUNTAINS PORTENDS
SIGNIFICANT SNOWFALL. THE SAN JUANS COULD SEE ANOTHER 2 FEET OF
SNOW WITH NEAR A FOOT POSSIBLE IN THE FOOTHILL AREAS BY MIDNIGHT
MONDAY. START TIME OF THIS EVENT IS EITHER LATE 5TH PERIOD
ACCORDING TO THE ECMWF AND NAM AND EARLY 6TH PERIOD ACCORDING TO
THE GFS40 AND THUS A BIT FAR OUT TO HOIST A WATCH JUST YET AS
DETAILS STILL A BIT SKETCHY.

LITTLE BREAK IN THE ACTION INDICATED TUESDAY AS ANOTHER LOW
DEEPENS OVER THE GREAT BASIN AND PUSHES INTO THE AREA IMPACTING
THE REGION THROUGH MIDWEEK. THE UNSETTLED WEATHER WILL CONTINUE
TO INHIBIT TEMPERATURES THROUGH THE REMAINDER OF THE WEEK AND INTO
THIS WEEKEND KEEPING READINGS BELOW SEASONAL NORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1037 AM MST WED FEB 25 2015

PRECIPITATION BRINGING IFR CONDITIONS T0 ASE AND TEX TERMINALS
LATE THIS MORNING. SOME SLIGHT IMPROVEMENT TO MVFR WILL OCCUR AT
TIMES THIS AFTERNOON AND POSSIBLY EVEN SOME BRIEF VFR BUT
IMPROVEMENT ABOVE ILS MARKERS NOT HIGHLY PROBABLE.
MOIST...UNSTABLE NORTHWEST FLOW LIKELY TO KEEP SHOWERS IN THE
HILLS THROUGH MIDNIGHT WITH MODELS INDICATING A SECONDARY PUSH
THIS EVENING. THERE COULD BE AREAS OF VALLEY FOG IN THE WAKE OF
THE PRECIPITATION BUT CONFIDENCE NOT OVERLY HIGH ATTM AND THIS
REFLECTED IN UPCOMING FORECAST. A BRIEF BREAK BEFORE THE NEXT PUSH
OF MOISTURE MAY BRING IMPROVED VFR CONDITIONS TO ALL THE FORECAST
TERMINALS LATE THURSDAY MORNING.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&

$$

UPDATE...15
SHORT TERM...JAM
LONG TERM...NL
AVIATION...TGJT



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