000
FXUS65 KGJT 181702
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1102 AM MDT SAT MAY 18 2013

.UPDATE...
ISSUED AT 1102 AM MDT SAT MAY 18 2013

THE UPPER TROUGH AXIS WAS OVER CENTRAL UTAH THIS MORNING AND WILL BE
ROTATING TO THE EAST AND NORTHEAST TODAY/TONIGHT. SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS WERE DEVELOPING AHEAD OF IT...WITH
COVERAGE EXPECTED TO INCREASE THIS AFTERNOON. PEA-SIZED OR A BIT
SMALLER HAIL WAS REPORTED FROM STORM OVER ORCHARD MESA (NEAR GRAND
JCT) AND ANOTHER NEAR MONTROSE EARLIER...AND THIS POSSIBILITY
SHOULD PERSIST THROUGH THE AFTERNOON. FREEZING LEVEL ON THIS
MORNING/S GJT SOUNDING WAS AROUND 11500 FT MSL. CURRENT FORECAST
LOOKS ON TRACK.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 314 AM MDT SAT MAY 18 2013

LIGHT SHOWERS QUICKLY DEVELOPING ACROSS EASTERN UTAH AND EXTREME
WESTERN COLORADO THIS MORNING IN DIFLUENT PATTERN OUT AHEAD OF
THE NEXT SHRTWV AND ASSOCIATED SFC FRONT. THIS SYSTEM WILL
PROGRESS SLOWLY EAST THROUGH THE FORECAST AREA TODAY...WITH
SHOWERS AND THUNDERSTORMS BECOMING FAIRLY WIDESPREAD BY THIS
AFTERNOON. HAVE BOOSTED POPS CONSIDERABLE ACROSS THE BOARD AND
ADJUSTED TIMING TO FIT WITH THE LATEST SHORT TERM MODELS. LOW
LEVELS WILL TAKE A BIT TO SATURATE...SO EARLY SHOWERS WILL BE A
BIT GUSTY...BUT EFFICIENT RAIN PRODUCERS WITH PRECIPITABLE WATER
VALUES IN EXCESS OF 0.50 INCH. SNOW LEVELS LOOK TO BE AROUND 10K
TODAY...ALTHOUGH CONVECTION WILL DRIVE IT DOWN TO NEAR THE 9K
LEVEL AT TIMES. NO SIGNIFICANT DAYTIME ACCUMULATIONS ANTICIPATED.
TEMPERATURES WILL BE MUCH COOLER TODAY WITH CLOUD COVER AND
FRONTAL PASSAGE EXPECTED THIS AFTERNOON.

UPPER LEVEL TROUGH PASSAGE OCCURS TONIGHT WITH THE 85KT JET CURVED
SOUTH OF THE FOUR CORNERS. WEAK COLD ADVECTION...CYCLONIC
FLOW...AND NW SLOPE OROGRAPHICS ALL INDICATE SHOWERS WILL CONTINUE
MAINLY OVER THE NORTH AND INTO THE CENTRAL MOUNTAINS. SNOW LEVELS
DROP TO AROUND 7500FT NORTH TO 10000FT SOUTH WITH 1-3 INCH
ACCUMULATIONS POSSIBLE OVER THE NORTHERN MTNS.

NW FLOW CONTINUES THROUGH MONDAY NIGHT BRINGING A COOL AND UNSETTLED
PERIOD. SUNDAY A SECOND OPEN WAVE DROPS THROUGH THE GREAT BASIN.
THIS BUILDS A BRIEF RIDGE OVER THE REGION THAT WILL DIMINISH POPS
BUT AFTERNOON CONVECTIVE SHOWERS REMAIN POSSIBLE. SNOW LEVELS RISE
TO ABOVE 10KFT MELTING MUCH OF THE SNOW THAT FELL IN THE HIGH
COUNTRY THE NIGHT BEFORE.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 314 AM MDT SAT MAY 18 2013

SUNDAY NIGHT-MONDAY...THE SECOND WAVE WORKS ACROSS THE REGION EARLY
MONDAY WITH THE BEST QG FORCING PROGGED TO PASS THROUGH THE SOUTHERN
PORTION OF THE FORECAST AREA. DIVERGENCE ALOFT IS CENTERED OVER THE
NORTH THROUGH THE AFTERNOON THAT MAY PROVIDE MORE CONVECTIVE
POTENTIAL. SNOW LEVELS LOWER TO AROUND 8KFT OVERNIGHT BUT RISE CLOSE
TO 10KFT THROUGH THE DAY. NIGHTTIME SNOW ACCUMULATIONS WILL MOSTLY
MELT AWAY THROUGH THE DAYTIME.

MONDAY NIGHT...THE TROUGH EXITS EAST AS A RIDGE BUILDS INTO THE
GREAT BASIN. SHOWERS WILL END QUICKLY WEST TO EAST THROUGH THE
EVENING.

RIDGING BUILDS IN TUESDAY AND WEDNESDAY WITH ONLY A FEW HIGH
MOUNTAIN SHOWERS EXPECTED DURING THE AFTERNOON AND EVENING HOURS
AS WE WORK OUT ANY LINGERING MOISTURE. DRY SOUTHWEST FLOW THEN
SETS IN THURSDAY AND WILL CONTINUE INTO THE WEEKEND WITH
TEMPERATURES RETURNING TO ABOVE SEASONAL NORMS AS WE CLOSE OUT
THE WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1102 AM MDT SAT MAY 18 2013

SCATTERED TO NUMEROUS -SHRA/-TSRA ARE EXPECTED THIS AFTERNOON
THROUGH 03Z THIS EVENING BEFORE DECREASING AND BECOMING MORE FOCUSED
ON THE NORTHERN AND CENTRAL MOUNTAINS IN WESTERN COLORADO AFTER 03Z.
SMALL HAIL AND GUSTY WINDS ARE POSSIBLE FROM SOME THUNDERSTORMS THIS
AFTERNOON. SNOW LEVEL AS LOW AS 8500 TO 9000 FT MSL IN CONVECTIVE
SHOWERS. EXPECT MOUNTAIN OBSCURATIONS AS CIGS LOWER IN THE VICINITY
OF SHOWERS WITH AREAS OF MVFR AND EVEN IFR CONDS EXPECTED. AT THE
TAF SITES...VFR CONDITIONS SHOULD BE THE RULE THOUGH A BRIEF PERIOD
OF MVFR CIGS IS POSSIBLE IN A THUNDERSTORM.

&&

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

$$

UPDATE...JAD
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...JAD