Debris Flow and Heavy Rain in Colorado, July 26, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
109 PM MDT SAT JUL 26 2008

.SHORT TERM (TONIGHT THROUGH MONDAY)...
CONVECTION HAS BEEN SLOW TO FIRE THIS AFTERNOON AS BLANKET OF MID
AND HIGH LEVEL CLOUDS HAS SLOWED SFC HEATING ACROSS THE FORECAST
AREA. A FEW STORMS HAVE FIRED ALONG THE PERIPHERY EDGES OF THE CLOUD
SHIELD IN NORTHEAST UTAH AND IN AREAS WHERE THE SHIELD IS THINNING
IN SOUTHEAST UTAH. DENSER CLOUD COVER IS ALSO PUTTING THE 90 PLUS
HIGH TEMPERATURE STRING IN JEOPARDY...ALTHOUGH ANY LATE AFTERNOON
THINNING OF THE CLOUD DECK WILL ALLOW THE VALLEY TO JUMP INTO THE
90S RATHER QUICKLY. CURRENT 90 PLUS DAYS STAND AT 41...WHICH IS
THIRD PLACE ALL TIME...THE RECORD IS 51 SET IN 1901.

A FEW DISTURBANCES LIFTING SLOWLY NORTH ACROSS ARIZONA AND UTAH WILL
BE PASSING THROUGH THE FORECAST AREA THIS EVENING...WHICH SHOULD BE
ENOUGH TO GET CONVECTION ROLLING FOR A FEW HOURS...BEFORE SHUTTING
DOWN AFTER MIDNIGHT. WILL MAINTAIN THE HIGH CHANCE POPS FOR THE
EVENING HOURS WITH INCREASING INSTABILITY EXPECTED WITH SHOT OF
COOLER AIR ALOFT MOVING OVER ASSOCIATED WITH THE WEAK WAVES. MORE
INTERESTING DEVELOPMENTS ARE ON SUNDAY AS THE REMNANTS OF HURRICANE
DOLLY LOOM TO OUR SOUTH.  THE SHORT-TERM MODELS ARE STRUGGLING WITH
THE EVOLUTION OF DOLLY TRACKING NORTH AND NORTHEAST ACROSS NEW
MEXICO...WITH THE HPC DISCUSSIONS FAVORING A GENERAL NWD TRACK INTO
CENTRAL NEW MEXICO...LIFTING NORTHEAST IN THE PLAINS BY LATE MONDAY.
THIS WILL PUT OUR SOUTHERN ZONES ON THE EDGE OF DEEPER SUB-TROPICAL
AIRMASS...WITH POTENTIAL FOR HEAVY RAINS ONCE AGAIN SUNDAY
AFTERNOON AND EVENING AS STORMS FIRE ON THE EDGE OF THE DEEPER
MOISTURE. NUDGED POPS UP A BIT FOR SUNDAY AFTERNOON TO ACCOUNT FOR
THIS ACTIVITY. CONVECTION LINGERS SUNDAY NIGHT...WITH ANOTHER ROUND
DUE ON MONDAY AS MONSOONAL FLOW PERSISTS FOR YET ANOTHER DAY.

TEMPERATURES WILL REMAIN NEAR SEASONAL NORMS FOR THE NORTHERN HALF OF
THE FORECAST AREA...WITH COOLER READINGS IN DEEPER MOISTURE AND
DENSER CLOUD COVER ACROSS THE SOUTH.

.LONG TERM (MONDAY NIGHT THROUGH SATURDAY)...

DRIER WEATHER INDICATED FOR MUCH OF THIS PERIOD AS THE MONSOONAL
MOISTURE PLUME AND REMNANTS OF DOLLY EXPECTED TO SLIDE TO THE EAST
MON NIGHT. PAC SHORTWAVE MOVES ACROSS THE NRN TIER OF STATES THAT
MODELS SHOW SUPPRESSES THE SWRN RIDGE AND MOISTURE AS WELL. NOT READY
TO COMPLETELY BUY OFF ON THE QUICKNESS AND EXTENT OF DRYING INDICATED
BY THE GFS AND ECWMF RUNS...BUT DID TREND THE CHANCE OF PRECIP DOWN
SOMEWHAT. STILL BELIEVE THERE WILL BE ENOUGH MOISTURE AND WARM TEMPS
FOR SCATTERED AFTERNOON/EVENING THUNDERSTORMS OVER THE CENTRAL AND
SRN MTNS.

&&

.AVIATION...ISOLATED TO SCATTERED THUNDERSTORMS CONTINUES THROUGH
TONIGHT WITH AN INCREASE IN COVERAGE EXPECTED ON SUNDAY...ESPECIALLY
ACROSS SOUTHERN COLORADO. LOCALLY HEAVY RAINFALL WILL OCCUR WITH SOME
STORMS...RESULTING IN MOUNTAIN OBSCURATION AND LOCALIZED MVFR AND IFR
CIGS AND VSBYS...ESPECIALLY SOUTH OF INTERSTATE 70.

&&

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

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
545 AM MDT SAT JUL 26 2008

COZ001>014-017>023-UTZ022>025-027>029-271200-
ANIMAS RIVER BASIN-ARCHES/GRAND FLAT-CANYONLANDS/NATURAL BRIDGES-
CENTRAL COLORADO RIVER BASIN-
CENTRAL GUNNISON AND UNCOMPAHGRE RIVER BASIN-
CENTRAL YAMPA RIVER BASIN-DEBEQUE TO SILT CORRIDOR-
EASTERN UINTA BASIN-EASTERN UINTA MOUNTAINS-
ELKHEAD AND PARK MOUNTAINS-FLAT TOPS-
FOUR CORNERS/UPPER DOLORES RIVER-
GORE AND ELK MOUNTAINS/CENTRAL MOUNTAINS-GRAND AND BATTLEMENT MESAS-
GRAND VALLEY-LA SAL AND ABAJO MOUNTAINS-LOWER YAMPA RIVER BASIN-
NORTHWEST SAN JUAN MOUNTAINS-PARADOX VALLEY/LOWER DOLORES RIVER-
ROAN AND TAVAPUTS PLATEAUS-SAN JUAN RIVER BASIN-SOUTHEAST UTAH-
SOUTHWEST SAN JUAN MOUNTAINS-TAVAPUTS PLATEAU-
UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE-UPPER GUNNISON RIVER VALLEY-
UPPER YAMPA RIVER BASIN-WEST ELK AND SAWATCH MOUNTAINS-
545 AM MDT SAT JUL 26 2008

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

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON EXCEPT ACROSS THE
NORTHERN VALLEYS WHERE ISOLATED STORMS ARE EXPECTED. LOCALLY HEAVY
RAIN WILL BE POSSIBLE...ALONG WITH SMALL HAIL AND VERY GUSTY WINDS.
RUNOFF FROM HEAVY RAIN MAY CAUSE SMALL CREEKS AND STREAMS TO RUN.
HEAVY RAIN MAY ALSO PRODUCE DEBRIS OR MUD FLOWS...AND CAUSE ARROYOS
TO QUICKLY FILL WITH WATER. THUNDERSTORMS WILL DECREASE AFTER
SUNSET...BUT ISOLATED SHOWERS OR STORMS WILL LAST BEYOND MIDNIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL
OCCUR EACH DAY SUNDAY THROUGH THURSDAY...WITH THE BEST CHANCE
OVER SOUTHEAST UTAH AND SOUTHWEST COLORADO. FEWER THUNDERSTORMS ARE
EXPECTED FRIDAY. LOCALLY HEAVY RAINFALL...GUSTY WINDS...AND SMALL
HAIL WILL BE POSSIBLE WITH THE THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED TODAY OR TONIGHT.

TAL/CJC