High Wind in Nevada, April 7, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
920 PM PDT WED APR 6 2005

.UPDATE...
A WIND ADVISORY WAS ISSUED FOR ALL ZONES FOR LATE TONIGHT THRU A
PORTION OF THURSDAY. THE TROUGH APPROACHING THE CA COAST WILL SWING
NEWD WITH A TIGHT PRESSURE AND TEMPERATURE GRADIENT SETTING UP EAST
OF THE SIERRA AHEAD OF THE ASSOCIATED COLD FRONT. SOUTH AND
SOUTHWEST WINDS WILL INCREASE LATER TONIGHT AHEAD OF THE FRONT. THE
REASONING FOR THE ADVISORY IS BASED ON THE SLOWER NAM MODEL WHICH
HAS BEEN PERFORMING BETTER WITH THE RECENT SHORTWAVE PASSAGES IN
DELAYING ONSET OF PRECIP...RESULTING IN A GREATER WINDOW OF
OPPORTUNITY FOR WINDS TO INCREASE BEFORE PRECIP SPREADS OVER THE
SIERRA CREST BY MIDDAY FRIDAY. THE 700 MB FLOW AND TIME OF MAX WIND
IS NOT OPTIMAL FOR HIGH WIND CRITERIA...EXCEPT FOR LOCAL GUSTS IN
WIND PRONE AREAS.

LITTLE OR NO PRECIP IS EXPECTED IN THE LEE SIDE ZONES AND THE WINDS
WILL DECREASE SLIGHTLY BY LATER FRIDAY AFTERNOON AFTER THE FRONT
PASSES AND WINDS SHIFT TO THE WEST. IN ADDITION...ONSET OF PRECIP
WILL BE DELAYED IN THE CA ZONES UNTIL THURSDAY. MJD

&&

.PREV DISCUSSION...
.SHORT TERM...
WARM HIGH PRESSURE RIDGE MOVES EAST THIS EVENING AS PACIFIC TROUGH
APPROACHES THE COAST. 140+ KT JET CONTINUES TO PUSH THIS TROUGH
EASTWARD AT A STEADY PACE. THERE WILL BE A NARROW WINDOW FOR
ACCUMULATING PRECIPITATION WITH THIS SYSTEM. AHEAD OF THIS SYSTEM
CLOUDS WILL CONTINUE TO INCREASE TODAY AND LOWER TONIGHT. WINDS WILL
ALSO INCREASE MAKING FOR A BREEZY AFTERNOON AND EVENING. 700MB FLOW
INCREASES TO 40-50KTS FROM LATE TONIGHT THROUGH FRIDAY MORNING.
WINDS WILL LIKELY INCREASE TO NEAR ADVISORY LEVELS DURING THAT TIME
FROM TAHOE NORTH IN THE SIERRA...AND ACROSS WRN NV FROM RENO NORTH.
DUE TO OVERNIGHT PERIOD...DECIDED NOT TO ISSUE A WIND ADVISORY
THINKING ADVISORY LEVEL WINDS WILL NOT MIX DOWN...BUT IT WILL BE
CLOSE. PRECIP ASSOCIATED WITH SYSTEM WILL MOVE INTO LASSEN COUNTY
AND THE TAHOE AREA OVERNIGHT. SNOW LEVELS WILL INITIALLY BE FAIRLY
HIGH...ABOVE 7000 FEET AT THE ONSET OF THE PRECIPITATION. SNOW
LEVELS WILL QUICKLY FALL TO VALLEY FLOORS ACROSS THE SIERRA AS COLD
FRONT MOVES THROUGH FROM WEST TO EAST DURING THE MORNING TOMORROW.
THE HEAVIEST PRECIP WILL FALL FROM THE EARLY MORNING HOURS UNTIL
NOON THURSDAY WITH UP TO 4-6 INCHES OF NEW SNOW ACCUMULATION
POSSIBLE AT THE HIGHEST ELEVATIONS. ONLY AN INCH OR TWO IS POSSIBLE
NEAR LAKE LEVEL WHERE THE SNOW WILL HAVE LESS TIME TO ACCUMULATE.
THEREFORE NO WINTER WEATHER STATEMENTS ARE ANTICIPATED AT THIS TIME.
LAKE WIND ADVISORIES WILL CONTINUE THROUGH THIS EVENING...BUT WILL
LIKELY BE NEEDED ONCE AGAIN ON THURSDAY.

THIS FIRST SYSTEM MOVES EASTWARD INTO UTAH BY FRIDAY MORNING WITH
NEXT SYSTEM CLOSE BEHIND. NEXT TROUGH TO DROP DOWN FROM THE
NORTHWEST ON FRIDAY AFTERNOON. THIS SYSTEM IS A LITTLE COLDER THAN
THURSDAYS SYSTEM AND WILL ALSO HAVE GOOD JET DYNAMICS TO WORK WITH.
120+ JET STREAM WILL NOSE INTO THE TAHOE AREA FRIDAY MORNING THEN
PARALLEL THE SIERRA FURTHER SOUTH AS SYSTEM DROPS DOWN. THESE
SYSTEMS TEND TO BE UNDERESTIMATED BY THE MODELS AS FAR AS HOW FAR
SOUTH THEY WILL MOVE. THEREFORE POPS WERE INCREASED ALONG THE SIERRA
AND EXTENDED FURTHER SOUTH INTO MONO COUNTY. A SNOW ADVISORY MAY
NEED TO BE ISSUED FOR FRIDAY AFTERNOON AND EVENING FOR THE SIERRA
FOR THIS SYSTEM. BUT ADDITIONAL MODEL DATA WILL ALLOW FUTURE SHIFTS
TO MAKE THIS CALL. MAX TEMPERATURES 10-15 DEGREES ABOVE NORMAL WILL
END TODAY...SUCCESSIVE TROUGH PASSAGES WILL KEEP HIGH TEMPS UP TO 10
DEGREES BELOW NORMAL THURSDAY THROUGH SATURDAY BEFORE ANOTHER WARM
UP BY THE END OF THE WEEKEND. BENINATO

.LONG TERM...SUNDAY THROUGH WEDNESDAY
PROGRESSIVE PATTERN SHOULD CONTINUE WITH FAVORED POSITION OF
POSITIVE ANOMALY SOUTH OF HUDSON BAY AND NEGATIVE ANOMALY GULF OF
ALASKA. THIS WOULD PROVIDE SOME SUPPORT FOR TROF INDICATED BY
GFS/ECMWF TO MOVE INTO PAC NW TUESDAY INTO WED. UNTIL THEN AREA
UNDER RIDGE FOR SUNDAY AND EARLY PART OF WEEK WITH TEMPERATURES
HEADING ABOVE NORMAL AGAIN. GFS IS THE MOST AMPLIFIED OF THE MEDIUM
RANGE MODELS WITH THE TROUGH LATE TUESDAY INTO WEDNESDAY SWEEPING
ACROSS THE GREAT BASIN. WILL THEREFORE STICK WITH CURRENT FORECAST
INDICATING WINDY CONDITIONS ON TUESDAY AND COOLER TEMPS WEDNESDAY
INTO THURS. PREVIOUS FORECAST HAD A SLIGHT CHANCE OF SHOWERS WITH
THIS TROUGH FAR NORTH PORTION OF NW NV AND NE CALIF AND WILL KEEP
THAT IN FORECAST AS THIS STILL LOOKS REASONABLE. HOLLINGSWORTH

&&

.REV WATCHES/WARNINGS/ADVISORIES...
.NV...WIND ADVISORY 4 AM TO 2 PM ZONES 1 3 4 AND 5.
      WIND ADVISORY 2 AM TO 11 AM ZONE 2.
.CA...WIND ADVISORY 4 AM TO 2 PM ZONE 70.
      WIND ADVISORY 2 AM TO 11 AM ZONES 71 72 AND 73.

&&