River Flood Advisory 2, NWS Reno, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
252 AM PDT TUE JUN 8 2010

.SHORT TERM...
ANOTHER SUNNY DAY IS IN ORDER WITH ABOVE NORMAL TEMPERATURES
ACROSS THE REGION AS ZONAL FLOW CONTINUES THROUGH THIS EVENING.
TOMORROW WILL SEE A PATTERN CHANGE AS A LOW PRESSURE SYSTEM
APPROACHES FROM THE NORTHWEST INTRODUCING COOLER AND BREEZY
CONDITIONS INTO THIS WEEKEND.

THE UPPER JET ASSOCIATED WITH THE TROUGH WILL DIP SOUTH ON WEDNESDAY
WHICH WILL INCREASE SOUTHWEST WINDS OVER THE SIERRA CREST AND
WESTERN NV WEDNESDAY INTO WEDNESDAY EVENING. THE ORIENTATION OF
THE JET IN THE GFS AND NAM SOLUTIONS FAVOR A BRIEF DOWNSLOPE WIND
EVENT DURING THE DAY WEDNESDAY WHILE THE ECMWF DOES NOT...AS IT
PUSHES THE JET FARTHER SOUTH. SUSTAINED WINDSPEEDS COULD BE AROUND
30 MPH WITH GUSTS AS HIGH AS 45 MPH IF THE DOWNSLOPE WINDS OCCUR.
STILL ONLY MODERATE CONFIDENCE DUE TO LACK OF MODEL AGREEMENT.
HOWEVER...EVEN IF THE DOWNSLOPE EVENT DOES NOT MATERIALIZE...GUSTY
CONDITIONS ARE STILL EXPECTED AHEAD OF THE COLD FRONT WEDNESDAY.

IN ADDITION TO BEING WINDY...TEMPERATURES WILL COOL CONSIDERABLY
WITH THIS SYSTEM. AFTERNOON HIGH TEMPERATURES WILL DROP AROUND 10
DEGREES ON WEDNESDAY AND ANOTHER 5 DEGREES ON THURSDAY IN THE COLD
POOL BEHIND THE FRONT. REGARDING TIMING OF THE FRONTAL PASSAGE...
IT LOOKS TO MOVE SOUTH THROUGH NORTHERN CA/NV EARLY THURSDAY
MORNING...SHIFTING WINDS TO THE NORTHWEST IN ITS WAKE.

AS FOR PRECIP...THIS LOOKS TO BE A RATHER DRY SYSTEM WITH
SHOWERS...IF ANY...AFFECTING ONLY THE SIERRA CREST AND NORTHERN
LASSEN AND WASHOE COUNTIES. PRECIPITABLE WATER ESTIMATES ARE UNDER
AN INCH WITH THIS SYSTEM SO QPF LOOKS TO BE NEGLIGIBLE WITH THE
EXCEPTION OF A FEW TENTHS IN SHOWERS OVER EXTREME NORTHERN WASHOE
COUNTY WEDNESDAY AND THURSDAY. LABELLE

.LONG TERM...FRIDAY THROUGH MONDAY...
MEDIUM RANGE MODELS APPEAR TO BE STUCK IN THE SAME SITUATION AS LAST
FEW DAYS WHERE OPERATIONAL GFS TRENDS TOWARD THE ECMWF/CANADIAN
SOLUTION EARLY IN THE EXTENDED FORECAST PERIOD THEN BEGINS TO VEER
QUITE A BIT BY THE LAST TWO DAYS OF THE PERIOD. TODAY THE GEFS
ENSEMBLE MEMBERS ARE AGAIN IN GOOD AGREEMENT WITH THE OPERATIONAL
ECMWF THROUGH DAY 5. BUT NOW THEY ARE SHOWING MUCH GREATER SPREAD IN
THEIR SOLUTIONS BY DAYS 6 AND 7. THIS IS LENDING EVEN LESS
CONFIDENCE TO THE FORECAST BEYOND SATURDAY.

UPPER LOW IS ENTRENCHED OVER THE AREA EARLY FRIDAY AND REMAINS SO
THROUGH SATURDAY. THIS PROVIDES A COOL COUPLE OF DAYS WITH TEMPS
WELL BELOW AVERAGE. BUMPED UP POPS JUST A BIT FOR SATURDAY AS WELL.
WITH OVERLAND TRAJECTORY OF THE UPPER LOW DO NOT THINK MSTR WILL BE
OVERLY ABUNDANT BUT COLD POOL ALOFT SHOULD HELP DEVELOP SHOWERS BOTH
DAYS WITH BEST COVERAGE OVER THE ERN CWA.

OPERATIONAL GFS IS STILL TRYING TO LIFT THE LOW OUT MUCH FASTER THAN
THE ECMWF AND MOST OF THE GEFS ENSEMBLE MEMBERS SUNDAY. DIFFERENCES
IN THE MODELS LEAD TO BIG DIFFERENCES IN THE FORECAST HIGHS. HAVE
OPTED TO TREND CLOSER TO THE ECMWF/GEFS ENSEMBLE COMPROMISE SOLUTION
AND HOLD A FEW MORE CLOUDS INTO THE RGN AND KEEP TEMPS BELOW MOS
GUIDANCE. ALL MODELS BUILD RIDGE BY MONDAY WITH GFS STRONGER. ECMWF
AND SOME GEFS ENSEMBLE MEMBERS ARE TRYING TO DEVELOP ANOTHER TROF IN
THE PAC NW BY LATE MONDAY WITH A SRN EXTENSION INTO THE NRN PORTIONS
OF OUR CWA. THIS WOULD RESULT IN GUSTY WINDS BY MONDAY AND MAYBE
BETTER MIXING. MONDAY SHOULD BE THE WARMEST DAY WITH TEMPS BACK
ABOVE AVERAGE. WILL HOLD PCPN OUT OF THE SUNDAY/MONDAY TIME FRAME
FOR NOW. MLF
&&

.AVIATION...
VFR THROUGH EARLY WEDNESDAY FOR ALL TAF SITES. GUSTY WINDS AGAIN
THIS AFTERNOON FROM THE WEST AT KTRK AND KRNO AND SOUTH AT KTVL.
GENERALLY GUSTS WILL APPROACH 20-25 KTS BUT SOME NEAR 30 KTS
POSSIBLE FOR KRNO AFTER 8/21 UTC.

WINDS WILL GUSTS HIGHER FOR WEDNESDAY AHEAD OF THE NEXT COLD FRONT.
WILL LIKELY SEE GUSTS AT KRNO IN THE 35-40 KT RANGE AFTER 9/20
UTC WHILE GUSTS AT KTRK AND KTVL WILL BE IN THE 25-30 KT RANGE.
MLF &&

.HYDROLOGY...
DAYTIME HIGHS WILL BE RATHER WARM AGAIN TODAY AND SHOULD RESULT IN
ANOTHER DAY OF GOOD MELTING. BUT THEN THE MELT WILL SLOW AS TEMPS
FALL 10 TO 15 DEGREES BY WEDNESDAY IN THE WAKE OF A COLD FRONT.
MANY STREAMS HAVE SEEN THEIR PEAKS ALREADY OR ARE EXPERIENCING
THEM RIGHT NOW...BASED ON MOST RECENT OBSERVATIONS FROM STREAM
GAGES AROUND THE AREA. THIS INCLUDES MANY STREAMS ON THE WEST SIDE
OF TAHOE AND IN THE UPPER REACHES OF THE CARSON BASIN. THE WEST
FORK OF THE WALKER ALSO APPEARS TO BE PEAKING WHILE THE EAST FORK
MAY HAVE ANOTHER NIGHT TO GO. ONE EXCEPTION IN THE TAHOE BASIN IS
TROUT CREEK...WHERE THE PEAKS ARE THE HIGHEST RIGHT NOW THAT HAVE
THUS FAR OCCURRED. THESE MAY CLIMB JUST A BIT MORE TONIGHT WITH
MORE GOOD DAY OF MELTING IN THE UPPER REACHES OF CREEK ABOVE SOUTH
LAKE.THE LOWER HIGH TEMPS LATER THIS WEEK WILL RESULT IN
SIGNIFICANTLY REDUCED FLOWS IN MOST SIERRA STREAMS. BUT FARTHER
DOWNSTREAM IN WRN NV THE PEAK MAY OCCUR EITHER WEDNESDAY OR THURSDAY.

EXPECT HIGH FLOWS AGAIN EARLY THIS MORNING IN THE TAHOE BASIN...THE
UPPER REACHES OF THE CARSON BASIN...THE WALKER BASIN AND THE SMALL
STREAMS THAT FLOW INTO MONO LAKE. WILL CONTINUE RIVER STATEMENT
FOR HIGH FLOWS IN PARTS OF THE TAHOE BASIN AND THE UPPER REACHES
OF THE CARSON. MEANWHILE A FLOOD WARNING REMAINS IN EFFECT FOR THE
WEST FORK OF THE WALKER RIVER DOWNSTREAM TO TOPAZ LAKE. THE
HIGHEST FLOWS AROUND WALKER AND COLEVILLE WILL BE THIS MORNING
WITH LESSER FLOWS WEDNESDAY MORNING. MAY DROP THE WARNING LATER
TODAY AND OPT FOR A FLOOD ADVISORY FOR LATE TONIGHT AND EARLY
WEDNESDAY. FLOW THIS MORNING SHOULD BE AROUND 3600 CFS BUT THEN
DROP TO AROUND 3200 CFS BY WEDNESDAY MORNING. MINOR LOW LAND
FLOODING WILL CONTINUE THIS MORNING WITH A DECREASE IN THE FLOW
BY AFTERNOON. THERE IS NO FLOODING EXPECTED DOWNSTREAM OF TOPAZ
LAKE ALONG THE WALKER RIVER IN NEVADA. ADDITIONAL DETAILS CAN BE
FOUND IN THE TOP NEWS SECTION OF OUR HOMEPAGE WEATHER.GOV/RENO AND
IN THE FOLLOWING PRODUCTS: RNOFLSREV...RNORVSREV AND RNOESFREV. DF/MLF
&&

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

HTTP://WEATHER.GOV/RENO