Flooding in California, June 24 to 30, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
245 AM PDT FRI JUN 24 2011

.SHORT TERM...

BROAD SCALE TROUGH ACROSS THE WEST TODAY WILL COOL HIGH
TEMPERATURES TO WITHIN A COUPLE DEGREES OF NORMAL. AIRMASS BEHIND
YESTERDAY'S COLD FRONT IS FAIRLY DRY WITH NO PRECIPITATION AND
LITTLE IN THE WAY OF CLOUDS EXPECTED TODAY. AFTERNOON THERMAL
TROUGH DEVELOPMENT WILL BRING TYPICAL AFTERNOON ZEPHYR WINDS TO
THE AREA WITH 20 TO 30 MPH GUSTS FRIDAY AND SATURDAY AFTERNOONS.
LAKES WILL BE CHOPPY BOTH THIS AFTERNOON AND SATURDAY
AFTERNOON...BUT WIND SPEEDS LOOK TO REMAIN BELOW LAKE WIND
ADVISORY CRITERIA.

A SHORTWAVE WILL MOVE THROUGH THE NORTHWEST SUNDAY...THOUGH NOT
MUCH MOISTURE OR INSTABILITY IS PRESENT AND THE MOST LIKELY IMPACT
WILL BE AFTERNOON CUMULUS DEVELOPMENT. THIS WAVE WILL NOT ALLOW
FOR THE THERMAL TROUGH TO BE AS STRONG AND THEREFORE AFTERNOON
WINDS WILL BE LIGHTER ON SUNDAY. DF

.LONG TERM...MONDAY THROUGH THURSDAY...

MEDIUM RANGE MODELS CONTINUE TO SHOW MORE AGREEMENT IN THE FIRST
HALF OF THE EXTENDED FORECAST PERIOD AS ALL DROP AN ANOMALOUSLY
COLD UPPER LOW TO JUST OFF THE COAST OF NRN CA BY EARLY WEDNESDAY.
THE MODELS DO START TO DIVERGE A BIT AFTER THAT AS THE GEM IS
SLOWER TO OPEN AND EJECT THE UPPER LOW THAN EITHER THE GFS OR
ECMWF OR MOST OF THE GEFS ENSEMBLE MEMBERS. SO BASICALLY THREW OUT
THE GEM AFTER WEDNESDAY MRNG AND TRENDED TOWARD THE GFS/ECMWF
CONSENSUS SOLUTIONS.

AHEAD OF THE TROF SHOULD SEE SLIGHTLY ABOVE AVERAGE TEMPS FOR MONDAY
THEN A COOL DOWN AS THE LOW NEARS WITH WEDNESDAY POSSIBLY 5 TO 10
DEGREES BELOW AVERAGE. BUMPED UP POPS A LITTLE FOR TUESDAY NIGHT
THROUGH WEDNESDAY NIGHT WITH MENTION OF THUNDER BOTH TUESDAY AND
WEDNESDAY. IF SYSTEM CONTINUES TO EVOLVE LIKE THIS WILL NEED TO
BUMP UP POPS EVEN MORE FOR WEDNESDAY. TROF DOES NOT APPEAR TO HAVE
MUCH OF A NEGATIVE TILT BUT WITH SOME INCREASING TURNING IN THE LOW
TO MID LVLS NOT OUT OF THE QUESTION TO DVLP SOME SUBSTANTIAL
THUNDERSTORMS BY LATE WEDNESDAY AFTN INTO THE WRN NV BASIN AND
RANGE. DID NOT MENTION THUNDER FOR WEDNESDAY NIGHT AS LOW LVL
INSTABILITY BEGINS TO DECREASE.

GFS HOLDS ON TO CYCLONIC FLOW ALOFT THURSDAY INTO THURSDAY NIGHT
WHILE ECMWF STARTS TO DVLP MORE RIDGING. FOR NOW WILL TREND DRY FOR
THURSDAY MORE IN LINE WITH THE ECMWF AS IT MORE RESEMBLES THE
TYPICAL PATTERN FOR LATE JUNE. MLF

&&

.AVIATION...

VFR CONDITIONS EXPECTED THROUGH THE NEXT 36 HOURS WITH TYPICAL
AFTERNOON WEST WINDS FOR WRN NV...ALTHOUGH NOT AS STRONG AS
YESTERDAY. DECREASING TEMPS TODAY COMPARED TO YESTERDAY WILL RESULT
IN LESS THERMAL GRADIENT FROM THE SIERRA TO THE WRN NV BASINS SO
WESTERLY GUSTS AT KRNO AND KTRK SHOULD REACH ONLY AROUND 20-25 KT IN
THE AFTERNOON. FOR KTVL SOUTHERLY WINDS LIKELY THROUGH THE DAY WITH
A BRIEF PERIOD BY EARLY AFTERNOON WHERE WINDS COULD SWITCH TO MORE
NNE OF THE LAKE. MLF

&&

.HYDROLOGY...

COOLER TEMPERATURES THIS WEEKEND WILL STABILIZE FLOWS ON AREA
RIVERS...CREEKS...AND STREAMS...EASING FLOOD CONCERNS.

THE WEST WALKER RIVER IS PEAKING EARLY THIS MORNING WITH THE GAGE
AT COLEVILLE REACHING ABOUT 6.52 FEET/3800 CFS...OR JUST A HAIR
ABOVE MODERATE FLOOD STAGE AND THE FLOOD WARNING CONTINUES
DOWNSTREAM TO JUST ABOVE TOPAZ LAKE. FURTHER DOWNSTREAM DIVERSIONS
INTO TOPAZ LAKE CONTINUE AND IT APPEARS THAT MUCH OF THE FLOOD
WAVE CAN BE CONTAINED AT TOPAZ. MAXIMUM RELEASES CONTINUE OUT OF
TOPAZ AS WELL. HOWEVER...IF FLOWS GET HIGHER ABOVE TOPAZ AND MORE
WATER NEEDS TO BE ALLOWED TO BYPASS TOPAZ LAKE...THEN MINOR
FLOODING WOULD STILL BE A CONCERN FOR THE SMITH VALLEY GOING INTO
THIS WEEKEND. THEREFORE...A FLOOD WATCH REMAINS IN EFFECT FOR THE
WEST WALKER BELOW TOPAZ LAKE.

FOR THE MAINSTEM WALKER...SNOWMELT RUNOFF COMBINED WITH RESERVOIR
RELEASES FROM BRIDGEPORT RESERVOIR AND TOPAZ LAKE ARE CONTRIBUTING
TO MODERATE TO POTENTIALLY MAJOR FLOODING FROM YERINGTON HEADING
DOWNSTREAM. A FLOOD WARNING REMAINS IN EFFECT FOR THE MAINSTEM
WALKER...SPECIFICALLY FOR MASON AND WABUSKA. INCREASED RELEASES
OUT OF WEBER DAM CONTINUE...BUT THE WALKER RIVER BELOW THE DAM IS
RUNNING BELOW BANKFULL. IT IS POSSIBLE THAT ADDITIONAL RELEASES
WILL BE NECESSARY AND SO A FLOOD WATCH REMAINS IN EFFECT FOR THE
MAINSTEM WALKER BELOW WEBER DAM.

OTHER MAINSTEM RIVERS ARE RUNNING HIGH...BUT NO FLOODING IS
EXPECTED AT THIS TIME.

FOR SMALLER CREEKS AND STREAMS IN THE SIERRA...

FOR THE TAHOE BASIN THE MAIN AREA OF CONCERN REMAINS TROUT CREEK
AS IT PASSES THROUGH SOUTH LAKE TAHOE. THE CREEK OVERRAN ITS
BANKS YESTERDAY MORNING...BUT IMPACTS WERE MINIMAL WITH ADDITIONAL
WATER RUNNING INTO NEARBY MEADOWS. THIS IS EXPECTED TO BE THE CASE
ONCE AGAIN THIS MORNING. THE AREAL FLOOD ADVISORY REMAINS IN
EFFECT. PEAK FLOWS IN THE SMALL STREAMS ALONG THE WEST SHORE ARE
LOWER THIS MORNING THAN YESTERDAY MORNING AND THIS TREND SHOULD
CONTINUE AS TEMPERATURES RETURN TO MORE AVERAGE READINGS.

FURTHER SOUTH IN MONO COUNTY STREAMS HAVE BEEN FLOWING AT BANKFULL
WITH LOCAL MINOR FLOODING REPORTED OVER THE PAST COUPLE OF DAYS
DURING THE EARLY MORNING HOURS....ESPECIALLY ABOVE BRIDGEPORT AND
IN THE LEE VINING AREA. THIS HAS AFFECTED SOME CAMPGROUNDS ALONG
LEE VINING CREEK WITH OTHER CAMPGROUNDS IN MONO COUNTY ALONG
WATERWAYS ALSO LIKELY IMPACTED. THE AREAL FLOOD WARNING WILL BE
CONTINUED FOR MONO COUNTY...GENERALLY FOR AREAS WEST OF HIGHWAY
395. DF/MLF

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

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