Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 291533 AAA
AFDGJT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
933 AM MDT SUN MAR 29 2015

.UPDATE...
ISSUED AT 933 AM MDT SUN MAR 29 2015

AS MENTIONED EARLIER...A WEAK FRONTAL ZONE AND NARROW BAND OF
MODERATE MID TO UPPER LEVEL MOISTURE WILL BE OVER SE UT AND SRN CO
THIS AFTN. A WEATHER SPOTTER IN CORTEZ REPORTED ALTOCUMULUS
CASTELLANUS THIS MORNING...AN INDICATION OF MID LEVEL INSTABILITY. FORCING
IS WEAK...BUT LATEST MODEL SOUNDINGS FAVOR WEAK CAPE AND STRONG
MID TO UPPER LEVEL LAPSE RATES WHICH SHOULD BE ENOUGH TO SUPPORT
ISOLATED TO SCATTERED CONVECTION OVER THE ABAJOS AND SAN JUAN
MTNS...WITH ISOLATED THUNDER ALSO POSSIBLE THIS AFTERNOON AND
EARLY EVENING. HAVE UPDATED POPS AND WEATHER FORECAST FOR
SOUTHERN PORTIONS TO INCREASE CHANCE OF RAIN SLIGHTLY AND INCLUDE
POSSIBILITY FOR THUNDERSTORMS. A GENEARLLY WESTERLY STEERING FLOW
SHOULD KEEP ANY SHOWERS THAT DO DEVELOP OVER THE MOUNTAINS.
OTHERWISE...ANOTHER SUNNY AND NEAR RECORD WARM DAY IS EXPECTED
ACROSS THE REGION.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 335 AM MDT SUN MAR 29 2015

THE WEAK BAROCLINIC BAND...BEST SEEN IN 500-300 DEFORMATION...WAS
STRETCHED BETWEEN THE I-70 AND HIGHWAY 50 CORRIDORS THIS EARLY
MORNING. THE BEST FORCING THIS EARLY MORNING WAS IN THE ELK MTNS
WITH LIGHT SHOWERS FROM VAIL PASS SOUTH TO MONARCH PASS. SHOWERS
BRIEFLY DROVE SNOW LEVELS TO AROUND 10KFT FEET BUT CAMERAS SHOWED
ONLY WET ROADS OVER VAIL PASS.

TODAY AND TONIGHT...LIGHT MOUNTAIN SHOWERS ARE POSSIBLE THIS
EARLY MORNING UNDER THIS DEFORMATION/FRONTAL BAND. IT WILL WEAKEN
AS IT SAGS INTO THE SAN JUANS TODAY BUT PROVIDES A FOCUS FOR
AFTERNOON SHOWERS. MOISTURE REMAINS MARGINAL ACROSS THE SOUTH
WITH PRECIP WATER VALUES AT 0.4 INCH AND 700MB SPECIFIC HUMIDITY
AT 4 G/KG. AFTERNOON SHOWERS WILL BE ALL RAIN AT ALL ELEVATIONS
WITH 700MB TEMPS AT 8C. INSTABILITY LOOKS INSUFFICIENT TO PRODUCE
LIGHTNING THOUGH AN ISOLATED STRIKE IN THE EASTERN SAN JUANS IS
POSSIBLE. SOUTHERN BUILDUPS SHOULD COLLAPSE QUICKLY WITH SUNSET.
MEANWHILE DRIER AIR NORTH OF I-70 WILL BRING MOSTLY CLEAR SKIES
TODAY AND TONIGHT.

MONDAY...MOISTURE BEGINS TO RETURN TO THE GREATER REGION FROM THE
WEST FOR ISOLATED AFTERNOON BUILDUPS MAINLY OVER THE MOUNTAINS.
THESE WILL PRODUCE MORE VIRGA AND ERRATIC OUTFLOW WINDS THAN
SHOWERS.

TEMPERATURES REMAIN VERY WARM FOR LATE MARCH. NEAR RECORD HIGHS
ARE POSSIBLE ACROSS THE SOUTH THIS AFTERNOON WHILE THE REST OF
THE FORECAST AREA WILL BE AROUND 15 DEGREES ABOVE NORMAL.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 335 AM MDT SUN MAR 29 2015

MOISTURE AND CLOUDS WILL CONTINUE TO FEED INTO THE AREA FROM THE
SOUTHWEST...BEING FED NORTH OVER AZ AND NM AS AIR ROTATES AROUND
AN OLD UPPER LOW OVER THE BAJA. THE MAIN LONGWAVE ANCHORS OVER
NORTH AMERICA WILL REMAIN THE HUDSON`S BAY LOW...THE RIDGE OVER
THE CENTRAL AND NORTHERN ROCKIES...AND THE LARGE TROUGH OFF THE
PACNW COAST AND IN THE GULF OF ALASKA. IN THE GFS...MODERATELY
STRONG SHORTWAVE TROUGHS WILL ROUND THE BOTTOM OF THE TWO LONGWAVE
TROUGHS MONDAY NIGHT AND TUESDAY...WHICH WILL CAUSE THE OVERALL
PATTERN TO SLIDE EAST. THUS THE WESTERN RIDGE BECOMES FLATTENED
AND SLIDES EAST AS A COLD FRONT MOVES INTO GREAT BASIN TUE...AND
THROUGH EASTERN UT AND WESTERN CO TUE NIGHT AND WED. THIS SENDS
MAX AND MIN TEMPS DOWN FROM 5 TO 10 DEGREES WED AND THU. THE ECMWF
HAS LESS AMPLITUDE WITH THIS TROUGH AND IS ABOUT 24 HOURS FASTER
WITH IT...WITH THE COLD FRONT PUSHING THROUGH BY LATE MONDAY NIGHT
AND TUESDAY.

THE EC REBOUNDS THE RIDGE FRIDAY AND SATURDAY AND SHOWS A
SHORTWAVE RUNNING ALONG THE US/CAN BORDER. THE GFS BRINGS A
REINFORCING TROUGH AND COLD FRONT INTO THE AREA THURSDAY WHICH
DROPS TEMPS EVEN MORE. IF THE GFS COMES TRUE FRUIT TREES AND
TENDER VEGETATION MAY BE AT RISK OF A FREEZE EARLY THU...FRI...AND
SAT MORNINGS...WITH THE THU NGT/FRI MORNING LOW TEMPS BEING THE
COLDEST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 335 AM MDT SUN MAR 29 2015

VFR CONDITIONS DOMINATE FOR THE NEXT 24 HOURS. ISOLATED MOUNTAIN
SHOWERS ARE POSSIBLE OVER THE CENTRAL AND SOUTHERN COLORADO
MOUNTAINS UNTIL 03Z THIS EARLY EVENING. OUTFLOW WIND GUSTS TO 30
MPH ARE POSSIBLE NEAR BUILDUPS. SUSTAINED WINDS WILL BE LIGHTER.


&&

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

$$

UPDATE...BEN
SHORT TERM...JOE
LONG TERM...CC
AVIATION...JOE



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