Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 191646
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1046 AM MDT FRI SEP 19 2014

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 359 AM MDT FRI SEP 19 2014

SPLITTING PACIFIC TROUGH SPARKING A LINE OF CONVECTION ACROSS
NORTHERN UTAH UP INTO WYOMING EARLY THIS MORNING. THIS ACTIVITY
ASSOCIATED WITH NORTHERN STREAM ENERGY THAT WILL DRAG ACROSS OUR
NORTHERN ZONES TODAY. THIS WILL BRING A SUBTLE INCREASE IN
CONVECTIVE COVERAGE BEGINNING LATE THIS MORNING ACROSS NORTHEAST
UTAH WITH ACTIVITY SLIDING EAST INTO NORTHWEST COLORADO THIS
AFTERNOON. IN ADDITION...DIURNALLY DRIVE SHOWERS AND STORMS WILL
DEVELOP OVER THE HIGHER MOUNTAINS NEAR PEAK HEATING. STEERING
FLOW SLACKS OFF THIS AFTERNOON...SO STORMS WILL HUG THE HIGHER
TERRAIN AND VALLEY DRIFTING STORMS APPEAR UNLIKELY ATTM. TEMPS
WILL REMAIN ABOVE NORMAL FOR YET ANOTHER DAY.

DAYTIME CONVECTION DIMINISHES THIS EVENING WITH MOSTLY CLEAR SKIES
EXPECTED AFTER MIDNIGHT. THE NORTHERN PORTION OF THE SPLIT TROUGH
SLIDES INTO THE NORTHERN PLAINS TONIGHT AS THE SOUTHERN PART REMAINS
JUST OFF THE SRN CA COAST AS A CUT-OFF LOW THROUGH SATURDAY. A WEAK
SHEAR BETWEEN THE TWO DISSIPATES ACROSS NW CO ON SAT AS THE UPPER
HIGH STRENGTHENS OVER THE CENTRAL ROCKIES. ISOLATED TO SCATTERED
STORMS ARE POSSIBLE OVER THE CO MTNS SAT AFTERNOON IN LIMITED
MOISTURE WITH DAYTIME HEATING...BUT MUCH OF THE FORECAST AREA WILL
EXPERIENCE WARM AND DRY CONDITIONS. MADE LITTLE CHANGE TO THE
CURRENT FORECAST FOR THESE PERIODS.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 359 AM MDT FRI SEP 19 2014

THE SRN CA LOW WORKS INLAND SAT NIGHT AND LIFTS NORTHEAST ACROSS NV
ON SUNDAY AS IT ENCOUNTERS THE MID-LEVEL LONGWAVE RIDGE OVER THE
WESTERN STATES. PRECIPITABLE WATER INCREASES TO AROUND 1 INCH IN THE
FOUR CORNERS AREA IN STRENGTHENING SOUTHERLY FLOW ALOFT. CLOUDS AND
THE CHANCE OF SHOWERS/THUNDERSTORMS INCREASE SUNDAY.

INCREASING SPEED AND DIRECTION SHEAR ARRIVES LATE SUNDAY AND
MONDAY AS THE LOW ACCELERATES ACROSS THE GREAT BASIN AND INTO
WYOMING. HAVE INCREASED POPS SIGNIFICANTLY SUNDAY NIGHT AS SHRTWV
ENERGY ROTATES THROUGH ON NOSE OF 50 KT JET MAX IN INCREASINGLY
DIFLUENT FLOW. SHEAR VALUES EXCEEDING 30KTS ACROSS THE EASTERN
UINTA BASIN AND INTO NORTHWEST COLORADO COULD ALSO LEAD TO A FEW
SPINNING CELLS INCREASING THE POTENTIAL FOR STRONG OUTFLOW WINDS
AND POTENTIALLY SEVERE HAIL. TIMING SUGGESTS THE BEST LIFT
ARRIVES DURING THE OVERNIGHT HOURS WHICH WOULD DAMPEN SEVERE
POTENTIAL A BIT...BUT SOMETHING TO WATCH AS WE HEAD INTO OUR
LIMITED WINDOW SEVERE WEATHER SEASON IN WESTERN COLORADO AND
EASTERN UTAH...OR EARLY FALL.

FLOW SWINGS TO MORE WESTERLY COMPONENT BY MONDAY AFTERNOON WHICH
WILL SHUT DOWN NORTHERN PROGRESS OF DEEPER MOISTURE AND IN TURN
DIMINISH CONVECTIVE POTENTIAL RATHER QUICKLY MONDAY EVENING AS THE
MAIN TROUGH AXIS SLIDES THROUGH. RIDGING BUILDS BACK IN TUESDAY
AND LOOKS TO HANG AROUND THROUGH THURSDAY BEFORE INFLUENCE OF
STRONG WESTERN TROUGH ARRIVES WITH STRENGTHENING SOUTHWEST FLOW
AND NORTHERN ADVECTION OF MOISTURE ON FRIDAY. VERY INTERESTING
PATTERN LATE IN THE WEEK AS STRONG CLOSED LOW DROPS INTO THE GREAT
BASIN WITH MUCH COOLER WEATHER ON TAP AS WE MOVE INTO THE FIRST
WEEK OF OCTOBER. MORE ON THAT LATER.

TEMPERATURES ARE EXPECTED TO REMAIN ABOVE NORMAL THROUGH THE
WEEKEND WITH MOS NUMBERS A GOOD START. COOLER WEATHER ARRIVES BY
THE BEGINNING OF THE WEEK WITH THE LOW DRIVING A SFC FRONT THROUGH
THE FORECAST AREA MONDAY NIGHT. TEMPS THEN EXPECTED TO HOLD AROUND
NORMAL FOR THE REMAINDER OF THE WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1046 AM MDT FRI SEP 19 2014

ISOLATED SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER THE MOUNTAINS
OF NORTHEAST UTAH AND WESTERN COLORADO THIS AFTERNOON. ACTIVITY
IS EXPECTED TO REMAIN ALONG THE HIGHEST RIDGES WITH LITTLE IMPACT
EXPECTED FOR VALLEY LOCATIONS TODAY. HOWEVER...GUSTY OUTFLOW WINDS
WILL OCCUR NEAR STORMS WITH SOME INCREASE IN SPEEDS EXPECTED AT
LOWER ELEVATIONS AS STORMS COLLAPSE LATE THIS AFTERNOON AND
EVENING. CONVECTION DIMINISHES AFTER 03Z THIS EVENING.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...NONE.
UT...NONE.

&&

$$

SHORT TERM...JDC/JAD
LONG TERM...JAD/JDC
AVIATION...NL


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