Weather Update

[Digger]

There's an opening in the storm door. Check the spinup just NW. of Hawaii
http://sat.wrh.noaa.gov/satellite/satloop.php?wfo=mtr&type=ir&size=16

Mammoth Weather cast
"SHORT AND SWEET.....MILD AND DRY WEEKEND EXTENDING INTO TUESDAY...THEN FIRST OF SERIES OF STORMS TO EFFECT THE HIGH COUNTRY AS EARLY AS WEDNESDAY......NEXT WEEKEND'S SYSTEM LOOKS LOWER IN LATITUDE AND THUS WETTER/STRONGER"

WARMER THAN NORMAL TEMPS WILL CONTINUE THROUGH NEXT TUESDAY. NIGHT TIME LOWS IN THE TEENS WILL WARM INTO THE LOWER 30S BY MONDAY AM.

AGAIN....WET WEATHER LOOKS PROBABLE TO DEVELOP BY WEDNESDAY OR WEDNESDAY NIGHT AS UNDERCUTTING OF THE WESTERLIES STILL FORECASTED BY ALL MODELS.

AT THE MOMENT, IT IS STILL TOO SOON TO PREDICT HOW MUCH SNOW WILL FALL OVER MAMMOTH MT. HOWEVER, THE PATTERN SUGGESTS THAT SNOW LEVELS WILL BE INITIALLY ON THE HIGHER SIDE.....THEN FALLING THROUGH WEEKS END......THERE IS THE POTENTIAL FOR SEVERAL FEET OF FRESH SNOW WITH AN EVEN LARGER STORM POSSIBLE FOR THE WEEKEND OF THE 10TH

H. Scheckter

[Digger]

THE PERSISTENT RIDGE OF HIGH PRESSURE OVER THE REGION WILL BREAK DOWN STARTING ON WEDNESDAY. THE FIRST STORM SYSTEM WILL MOVE INTO THE AREA ON WEDNESDAY AFTERNOON AND WILL LIKELY BRING SEVERAL INCHES OF SNOW TO THE SIERRA ABOVE 7000 FEET...WITH RAIN AT LOWER ELEVATIONS OF THE SIERRA AND WESTERN NEVADA.

DEEPER SUBTROPICAL MOISTURE WILL MOVE INTO THE SIERRA BY THURSDAY WITH SEVERAL WAVES OF HEAVY PRECIPITATION EXPECTED THROUGH THE WEEKEND. SEVERAL INCHES OF LIQUID PRECIPITATION ARE EXPECTED IN THE SIERRA THROUGH SUNDAY...WITH 1 TO 3 INCHES OF RAIN POSSIBLE IN THE LOWER ELEVATIONS OF NORTHEAST CALIFORNIA AND WESTERN NEVADA. SNOW LEVELS ARE EXPECTED TO RISE TO 7000 TO 8000 FEET IN THE NORTHERN SIERRA THURSDAY NIGHT AND FRIDAY.

PERIODS OF HEAVY PRECIPITATION AND RELATIVELY HIGH SNOW LEVELS BRINGS THE THREAT OF FLOODING TO THE SIERRA AND WESTERN NEVADA THROUGH SUNDAY. AT THIS POINT IT IS VERY DIFFICULT TO DETERMINE IF ANY FLOODING WILL OCCUR...AND TO WHAT EXTENT. IT WILL TAKE TIME TO MOISTEN SOME DRY SOILS...SO THAT MAY LIMIT PROBLEMS TO INCREASED RIVER LEVELS. HOWEVER AREAS THAT ARE MOIST FROM SNOWMELT...SMALL CREEKS AND STREAMS IN THE HIGHER ELEVATIONS...SMALL BASINS LIKE THE SUSAN RIVER...HAVE THE HIGHEST POTENTIAL FOR FLOODING. PERSONS ALSO NEED TO BE WARY OF STEEP SLOPES FOR ROCK AND MUD SLIDES.

SIGNIFICANT SNOW AMOUNTS ARE ALSO EXPECTED IN THE HIGH SIERRA...WITH SEVERAL FEET OF SNOW POSSIBLE ABOVE 7000 TO 7500 FEET BY SUNDAY.

THE MAIN UNCERTAINTIES IN THE FORECAST FOR THE WEEKEND ARE SNOW LEVELS...LIQUID PRECIPITATION AMOUNTS AND IF ANY FLOODING WILL OCCUR. THESE FORECAST ELEMENTS WILL BECOME MORE CLEAR IN THE NEXT COUPLE OF DAYS. PERSONS WITH INTERESTS IN THE HIGH SIERRA...AS WELL AS DOWN TO VALLEY FLOORS NEED TO KEEP A CLOSE EYE ON THE WEATHER AND ANY UPDATES OR CHANGES TO THE FORECAST IN THIS POTENTIALLY SIGNIFICANT SITUATION

[Digger]

Posted : Tue, February 20, 2007 at 10:30 AM

"MAJOR STORM ON THE WAY BEGINNING LATE WEDNESDAY NIGHT.....FULL ON WINTER STORM CONDITIONS LIKELY THURSDAY....A PROGRESSIVE PATTERN NOW ALLOWS A SERIES OF STORMS TO MARCH ACROSS THE HIGH COUNTRY...ONE ABOUT EVERY THREE DAYS, NOW THAT HUDSON BAY LOW IS GONE.....A RAPIDLY DEVELOPING LA NINA IS NOW OCCURING OVER THE EAST-CENTRAL TROPICAL PACIFIC AND SPREADING EAST-WEST......SETTING THE STAGE FOR AN EARLY, HOT SUMMER WITH LOTS OF HIGH BASED THUNDERSTORMS FOR THE HIGH COUNTRY....NO DOUBT THAT THIS UP-COMING SUMMER AFTER THE DRY WINTER WILL BE A NIGHTMARE FOR FIRE CREWS LATER THIS YEAR"

CONFIDENCE INCREASING AGAIN FOR THE WEDNESDAY NIGHT THROUGH FRIDAY STORM.....STILL THE ECMWF HAS SYSTEM SPLITTING A BIT...CURRENT AMERICAN GFS HAS POWERHOUSE JET AND VERY STRONG DIVERGENCE ALOFT WITH MID WEEK SYSTEM.....-32 AT 500MB FRIDAY TELLS ME THAT THERE IS A LOT OF POTENTIAL WITH THIS STORM...HOWEVER AGAIN....IT IS COMING IN A BIT NEGITIVE TILT AND WITH THE STRONG DIGGING JET AND ALL THAT COLD AIR...IT VERY WELL COULD SPLIT! .... IF IT DOES COME IN IN ONE PIECE, IT WILL BE A POWDER-KEG..WITH A GOOD TWO FEET TO THREE FEET OF POWDER OVER THE HIGHER ELEVATIONS.

H. Scheckter

[lee s.]

Thanks Digger,
Was wondering.....
Looks like we have time for one more load from Alturas before it gets nasty.......nasty for driving/BEAUTIFUL for the fishes. 8)
.....lee s.

[Digger]

Ridge building will be pronounced across the Great Basin over the weekend, resulting in warming temperatures aloft and dry, offshore-directed flow descending the western slopes of the Sierras. Hence, surface temperatures across the ARB will also warm noticeably (perhaps to above normal by Sat.) with no chance of significant precipitation.

We should see little more than thickening cirrus/altostratus across the ARB on Sunday. Decreasing clouds will follow the passage of the short wave Sunday night into Monday.

A much more substantial storm may be on the horizon for the late Mon. to Wed. timeframe. The GFS has been consistent in bringing a significant atmospheric river event ashore in northern CA with high snow levels during this period. Given the new snow that has accumulated to quite low altitudes in the ARB recently, this storm could pose hydro problems. Interestingly, the EC model has consistently kept most of the wave energy and moisture with this pending storm to the north of the ARB, as does the new Canadian spectral solution. All long-range models are suggesting a prolonged juicy atmospheric-river event somewhere in the northern half of the U.S. West Coast during the lattertwo-thirds of next week. This potentially significant West Coast storm should be interesting to watch unfold.

Paul Neiman

[bigtj]

Weather forecasts this time of year are a real crapshoot. Looks like we've got some good weather this weekend, which is nice though which is good to see.