Flash Flood Warning 48, NWS Grand Junction, CO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
320 PM MDT SAT SEP 14 2013

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 320 PM MDT SAT SEP 14 2013

UPPER LOW CIRCULATION THAT IS CURRENTLY OVER NRN UTAH WILL BE
SENDING MOIST SHORT WAVES ACROSS THROUGH SUNDAY EVENING. MORNING
SOUNDING AT KGJT SHOW A MOIST ADIABATIC LAPSE RATE. CLOUD BASES
ARE RELATIVELY LOW PER VISUAL AND WEB PICTURE POSTINGS. SLOW
MOVING UPPER LOW SHOW A NEGATIVE TILT ORIENTATION WITH UPPER
DIVERGENCE ACROSS THE FORECAST AREA. THIS FEATURE IS PROGGED TO
REACH WEST CENTRAL COLORADO BY SUNDAY AFTERNOON...THEN APPROACHING
THE DIVIDE BY LATE SUNDAY EVENING. STORM DEVELOPMENT MORE
DEPENDENT ON SURFACE HEATING AND DYNAMICAL LIFT ASSOCIATED WITH
THE UPPER LOW...NOT SO DEPENDENT ON THE TERRAIN.  WITH COLD CORE
UPPER LOW TRACKING OVERHEAD ON SUNDAY...AREAL COVERAGE OF SHOWERS
WITH EMBEDDED THUNDERSTORMS WILL BE NUMEROUS. WITH NORMALLY DRY
WASHES RESPONDING MUCH FASTER TO HEAVY SHOWERS...ELECTED TO HOIST
FLASH FLOOD WASH FOR RED ROCK AND CANYON COUNTRY PORTION OF THE
FORECAST AREA.

IN THE HIGH COUNTRY...NIGHTTIME SNOW LEVELS HAVE LOWERED TO ABOUT
12K FEET. THIS IS ABOVE MOUNTAIN PASS LEVEL...EXCEPT FOR
BACKCOUNTRY DIRT OR JEEP ROADS. SOME SNOW ACCUMULATIONS OF 1 TO
2 INCHES ABOVE 12K COULD OCCUR AGAIN TONIGHT.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 PM MDT SAT SEP 14 2013

WESTERLY FLOW WILL DEVELOP MONDAY AS THE UPPER LEVEL SYSTEM
WEAKENS AND MOVES EAST. A SHORTWAVE RIDGE WILL BUILD OVER THE
GREAT BASIN AND THE CENTRAL ROCKIES BY MONDAY NIGHT...BEGINNING A
DRYING TREND FROM WEST TO EAST. ISOLATED TO SCATTERED SHOWERS ARE
STILL EXPECTED TO DEVELOP MAINLY OVER HIGHER TERRAIN FROM
LINGERING MOISTURE AROUND THE REGION...BUT WILL LESSEN AS THE WEEK
GOES ON.

AN UPPER LEVEL TROUGH EJECTING FROM A STRONG PACIFIC NORTHWEST
LOW IS FORECAST TO DROP INTO THE NORTHERN PART OF THE AREA
WEDNESDAY BEFORE PROGRESSING TO THE EAST THURSDAY. THIS WILL HELP TO
PROVIDE DYNAMICS WEDNESDAY TO HELP FUEL SHOWERS AND THUNDERSTORMS
DESPITE A DRYING AIRMASS. AS THIS TROUGH PASSES ACROSS THE
INTERMOUNTAIN WEST WED...GRADIENT WEST TO SOUTHWEST WINDS WILL
INCREASE ACROSS WESTERN CO AND EASTERN UT. FRIDAY AND SATURDAY SHOULD
REMAIN DRY WITH RIDGING CONTINUING.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY AFTERNOON)
ISSUED AT 320 PM MDT SAT SEP 14 2013

A SLOW MOVING SYSTEM WILL BE CROSSING EASTERN UTAH AND WESTERN
COLORADO OVER THE NEXT 24 TO 36 HOURS KEEPING A THREAT OF SHOWERS
AND THUNDERSTORMS ACROSS THE AREA THROUGH THIS TIME. THOUGH VFR
CONDITIONS ARE LIKELY TO PREVAIL THROUGH MUCH OF THIS FORECAST
PERIOD...LOWERED FLIGHT CONDITIONS MAY QUICKLY MOVE NEAR THE SHOWERS
AND STORMS WITH MODERATE TO HEAVY RAINFALL MAY TEMPORARILY INHIBIT
BOTH VSBY AND CIGS. MOUNTAIN OBSCURATIONS WILL BE WIDESPREAD AND
AREAS OF PATCHY FOG AND LOW CLOUDS MAY DEVELOP DURING THE EARLY
MORNING AREAS AS WELL.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...FLASH FLOOD WATCH THROUGH SUNDAY EVENING FOR COZ003-006-011-
     017>023.

UT...FLASH FLOOD WATCH THROUGH SUNDAY EVENING FOR UTZ022-025-027>029.

&&

SHORT TERM...PF
LONG TERM...JAM
AVIATION...15

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
350 AM MDT SAT SEP 14 2013

COZ001>014-017>023-UTZ022>025-027>029-151000-
LOWER YAMPA RIVER BASIN-CENTRAL YAMPA RIVER BASIN-
ROAN AND TAVAPUTS PLATEAUS-ELKHEAD AND PARK MOUNTAINS-
UPPER YAMPA RIVER BASIN-GRAND VALLEY-DEBEQUE TO SILT CORRIDOR-
CENTRAL COLORADO RIVER BASIN-GRAND AND BATTLEMENT MESAS-
GORE AND ELK MOUNTAINS/CENTRAL MOUNTAIN VALLEYS-
CENTRAL GUNNISON AND UNCOMPAHGRE RIVER BASIN-
WEST ELK AND SAWATCH MOUNTAINS-FLATTOPS-
UPPER GUNNISON RIVER VALLEY-UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE-
NORTHWEST SAN JUAN MOUNTAINS-SOUTHWEST SAN JUAN MOUNTAINS-
PARADOX VALLEY/LOWER DOLORES RIVER-
FOUR CORNERS/UPPER DOLORES RIVER-ANIMAS RIVER BASIN-
SAN JUAN RIVER BASIN-SOUTHEAST UTAH-EASTERN UINTA MOUNTAINS-
EASTERN UINTA BASIN-TAVAPUTS PLATEAU-ARCHES/GRAND FLAT-
LA SAL AND ABAJO MOUNTAINS-CANYONLANDS/NATURAL BRIDGES-
350 AM MDT SAT SEP 14 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN
COLORADO.

.DAY ONE...TODAY AND TONIGHT

SCATTERED TO NUMEROUS SHOWERS WITH EMBEDDED THUNDERSTORMS WILL
CONTINUE TODAY AND THIS EVENING...FAVORING HIGHER TERRAIN. SOME
STORMS WILL PRODUCE BRIEF HEAVY RAIN.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

EXPECT A SLOW DECREASE IN AREAL COVERAGE OF SHOWERS AND
THUNDERSTORMS THROUGH EARLY NEXT WEEK. GENERALLY...SCATTERED SHOWERS
AND THUNDERSTORMS ARE EXPECTED WITH PRECIPITATION FAVORING HIGHER
TERRAIN. THE THREAT OF BRIEF HEAVY RAIN WILL CONTINUE WITH STORMS
BUT THIS WILL BECOME MORE ISOLATED.

TUESDAY THROUGH FRIDAY...MUCH DRIER AIR WILL MOVE INTO THE AREA
WITH ONLY A SLIGHT CHANCE OF AFTERNOON AND EARLY EVENING SHOWERS
AND THUNDERSTORMS...MAINLY OVER THE MOUNTAINS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED TODAY OR TONIGHT...HOWEVER
SPOTTERS ARE ENCOURAGED TO RELAY RAINFALL AMOUNTS OR ANY OBSERVED
FLOODING TO THE GRAND JUNCTION FORECAST OFFICE.

CJC/ELH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
305 PM MDT SAT SEP 14 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0303 PM     FLASH FLOOD      CANYONLANDS NP - NEEDLE 38.15N 109.78W
09/14/2013                   SAN JUAN           UT   CO-OP OBSERVER

            ALL FOUR WHEEL DRIVE ROADS HAVE BEEN CLOSED AND ACCESS
            ROAD TO ELEPHANT HILL HAS WATER RUNNING OVER IT.

&&

EVENT NUMBER GJT1301509

15

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
330 PM MDT SAT SEP 14 2013

COZ004-010-012-013-018-019-150930-
ELKHEAD AND PARK MOUNTAINS-
GORE AND ELK MOUNTAINS/CENTRAL MOUNTAIN VALLEYS-
WEST ELK AND SAWATCH MOUNTAINS-FLATTOPS-
NORTHWEST SAN JUAN MOUNTAINS-SOUTHWEST SAN JUAN MOUNTAINS-
INCLUDING THE CITIES OF...COLUMBINE...TOPONAS...ASPEN...VAIL...
SNOWMASS...CRESTED BUTTE...TAYLOR PARK...MARBLE...BUFORD...
TRAPPERS LAKE...OURAY...TELLURIDE...LAKE CITY...SILVERTON...
RICO...HESPERUS
330 PM MDT SAT SEP 14 2013

...SOME LIGHT SNOW ACCUMULATION ABOVE 12,000 FEET TONIGHT AND
EARLY SUNDAY MORNING...

LIGHT SNOW ACCUMULATIONS ARE EXPECTED IN THE HIGH COUNTRY ABOVE
12,000 FEET. POSSIBLE ACCUMULATIONS OVERNIGHT MAY RANGE FROM 1 TO
2 INCHES. PEOPLE TRAVELING ON BACKCOUNTRY ROADS AND HIKERS MAY BE
AFFECTED BY FRESH SNOW ABOVE 12,000 FEET TONIGHT AND SUNDAY MORNING.

GIVEN THE RECENT RAINFALL DURING THE PAST WEEK...MANY BACKCOUNTRY
ROADS MAY EXPERIENCE MUD DEBRIS FLOW OR ROCKSLIDES. BACKCOUNTRY
TRAVEL INTO THE HIGH COUNTRY MAY BE DIFFICULT REGARDLESS OF
ELEVATION.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
355 PM MDT SAT SEP 14 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 PM     FLASH FLOOD      11 NW SUMMIT PT         38.15N 109.28W
09/13/2013                   SAN JUAN           UT   TRAINED SPOTTER

            NO WATER TO KNEE DEPTH WATER FLOW IN ELEPHANT CANYON

&&

EVENT NUMBER GJT1301510

PF

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
523 PM MDT SAT SEP 14 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0456 PM     FLASH FLOOD      NUCLA                   38.27N 108.55W
09/14/2013                   MONTROSE           CO   DEPT OF HIGHWAYS

            FOLLOW UP CALL TO CDOT. HWY 90 MM 25 IN PARADOX VALLEY
            FLOODING WITH 6 INCHES OVER THE ROAD. NUCLA... SMALL
            HAIL TO DEPTH OF ONE INCH. MUD SLIDE BEING CLEANED UP ON
            HWY 141 MM 63 TO MM 68.

&&

EVENT NUMBER GJT1301513

BK