Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 270506
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1106 PM MDT FRI SEP 26 2014

.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 344 PM MDT FRI SEP 26 2014

HIGH PRESSURE WAS ACROSS THE AREA TODAY. A FEW SHOWERS/THUNDERSTORMS
HAVE DEVELOPED OVER THE SRN SAN JUAN MTNS AT MID-AFTERNOON. A FEW
MORE STORMS ARE POSSIBLE OVER THE SAN JUANS AND UP THE CENTRAL
DIVIDE UNTIL SUNSET.

THE NEXT SIGNIFICANT WEATHERMAKER FOR ERN UT/WRN CO WAS ALONG THE
WEST COAST THIS AFTERNOON. THIS COOL PACIFIC TROUGH WAS IN THE
PROCESS OF SPLITTING AND DEVELOPING A CLOSED LOW ALONG THE CA COAST.
THIS UPPER LOW THEN MOVES TO THE CENTRAL CA/NV BORDER BY SAT
MORNING...AND SLOWLY TRUDGES EAST ACROSS NV SAT AND SAT NIGHT.
MODELS ALL IN GENERAL AGREEMENT ON STRENGTHENING SOUTHERLY FLOW
AHEAD OF IT PULLING ABUNDANT MOISTURE UP FROM NW MEXICO AND GULF OF
CA REGION ALONG A BAROCLINIC/FRONTAL BAND THAT HPC CURRENTLY HAS
SNAKING FROM SRN CA ACROSS NV AND WRN WY. SUBSEQUENTLY...TENDED TO
FOLLOW THE CONSENSUS MODEL WHICH SHOWS THIS MOISTURE PLUME MOVING
OVER OUR AREA SAT NIGHT INTO SUNDAY.

CLOUDS AND SHOWERS/THUNDERSTORMS WILL SPREAD IN FROM THE WEST SAT
AFTERNOON. DECENT CAPE PROJECTED SO SOME STORMS COULD BE STRONG WITH
GUSTY WINDS AND SMALL HAIL...ESPECIALLY ACROSS ERN UT WHERE BETTER
0-6KM VERTICAL SHEAR SHOULD EXIST.

RAIN WILL BECOME WIDESPREAD SAT NIGHT ACROSS ALL BUT THE FAR EASTERN
PORTION OF THE FORECAST AREA AS THE DEEPEST MOISTURE AND BEST
SYNOPTIC LIFT ARRIVE. SOME EMBEDDED THUNDERSTORMS WILL CONTINUE.
WITH PRECIPITABLE WATER VALUES OF 1 INCH OR MORE FORECAST ALONG THE
UT/CO SAT NIGHT...SUBSTANTIAL RAINFALL COULD ACCUMULATE OVER TIME
ESPECIALLY IF SHOWERS/STORMS REPEATEDLY MOVE OVER THE SAME AREAS.
PEOPLE OUTDOORS THIS WEEKEND SHOULD BE WARY IN CANYON AND SLICK ROCK
COUNTRY OF STORM DEVELOPMENT. IN OTHER AREAS...WHILE SOILS HAVE
DRIED SOME THIS WEEK...SOIL MOISTURE REMAINS ELEVATED IN MANY AREAS
FROM EARLIER THIS MONTH AND MAY RESPOND QUICKER TO ADDITIONAL
RAINFALL THIS WEEKEND.

WILL ISSUE A MULTI-MEDIA WEATHER BRIEFING VIDEO AND A SPECIAL
WEATHER STATEMENT TO HIGHLIGHT THIS CHANGE AND THE POTENTIAL FOR
SIGNIFICANT RAINFALL THIS WEEKEND...AND SHIFT TO MORE AUTUMN-LIKE
TEMPS NEXT WEEK. LATER SHIFTS CAN CONTEMPLATE A FLASH FLOOD WATCH AS
THE AREAS MOST LIKELY IMPACTED BECOME MORE DEFINED TEMPORALLY AND
A REALLY.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 344 PM MDT FRI SEP 26 2014

A 70KT JET STREAK WILL ROTATE INTO THE FORECAST AREA ON SUNDAY
MORNING...INCREASING LARGE SCALE ASCENT FOR EFFICIENT
PRECIPITATION DEVELOPMENT. EXPECTING WIDESPREAD PRECIPITATION
AHEAD OF THE APPROACHING COLD FRONT THROUGHOUT MUCH OF SUNDAY.
310K MOISTURE TRANSPORT IS STRONGEST ALONG THE UT/CO BORDER THEN
WEAKENS SLIGHTLY AS MOISTURE GETS SQUEEZED OUT AS IT REACHES THE
MOUNTAIN RANGES IN THE AREA. THERE IS SLIGHT POTENTIAL FOR
ISOLATED FLASH FLOOD EVENTS NEAR HEAVIER SHOWERS...AND IN AREAS
WHICH ARE ALREADY SATURATED FROM PREVIOUS STORMS ON SATURDAY.
HOWEVER...PRECIPITABLE WATER VALUES WILL NOT BE PARTICULARLY HIGH
ON SUNDAY SO MORE THAN LIKELY WE WILL END UP WITH STRATIFORM
PRECIPITATION WITH EMBEDDED CONVECTIVE SHOWERS AND THUNDERSTORMS.
THE STRONGER THUNDERSTORMS ON SUNDAY COULD POTENTIALLY CREATE
STRONG WINDS AND NEAR SEVERE SIZED HAIL...ESPECIALLY IN EASTERN
UTAH.

THE ASSOCIATED COLD FRONT WILL REACH EASTERN UTAH MONDAY MORNING
AND TREK EAST ACROSS WESTERN COLORADO DURING THE DAY MONDAY.
HAVE INCREASED WINDS AND WIND GUST GRIDS FOR THE ESTIMATED FRONTAL
PASSAGE TIMEFRAME ON MONDAY. SNOW LEVEL IS EXPECTED TO DROP TO
AROUND 10KFT BEHIND THE COLD FRONT DURING THE DAY ON
MONDAY...WHICH IS THE LOWEST IT WILL BE SO FAR THIS SEASON.
PRECIPITABLE WATER VALUES SUGGEST DRIER AIR FILTERING INTO THE
REGION RIGHT BEHIND THE COLD FRONT PASSAGE...SO KEPT SHOWERS
ISOLATED TO SCATTERED DURING THE DAY MONDAY. COULD SEE SOME LIGHT
ACCUMULATIONS...BUT WITH WARM SFC TEMPS...THINKING THERE IS
LITTLE CHANCE OF ACCUMULATIONS ON MOUNTAIN PASS ROADS.

DRIER AND COOLER AIR IN NORTHWEST FLOW WILL PERSIST THROUGHOUT
THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1057 PM MDT FRI SEP 26 2014

SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE ACROSS SOUTHEAST
UTAH AND SOUTHWEST COLORADO AFTER 18Z SATURDAY. STORMS WILL
CONTINUE MOVING NORTH AND EAST TO ENCOMPASS ALL OF EASTERN UTAH
AND WESTERN COLORADO BY SATURDAY EVENING. CIGS AND VSBYS WILL BE
DROPPING SATURDAY NIGHT AS PRECIPITATION BECOMES MORE STRATIFORM
IN NATURE. VFR CONDS EXPECTED TO PERSIST THROUGH 00Z SATURDAY
EVENING...THEN AREAS OF MVFR AND IFR CONDS ARE EXPECTED TO DEVELOP
WITH MOUNTAINS BECOMING FQTLY OBSCD.

&&

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

$$

SHORT TERM...JAD
LONG TERM...JAM
AVIATION...JDC


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