Monday, October 5, 2009

Weather, El Nino Update, & Water Year Re-Cap.........

Now that the snow is starting to fall in the Tahoe area this blog will become more Northstar specific.  Please visit the Tahoe Weather Home Page for a general discussion.

It was a cold & snowy Sunday in the Lake Tahoe area.  From the webcams it appears that Northstar got a few inches on top & a coating at the bottom.  One band of snow came thru in the early morning hours Sunday & another in the evening.  It will stay cold today as the storm heads into the Rockies.  Temps will slowly warm each day this week as we head towards the weekend.  A ridge will be building off the coast all week warming temps into the 60's by midweek.

Models continued to suggest over the weekend that the ridge might flatten & retrograde towards the Central Pacific next week.  This would allow a strong Pacific jet to come into the Pac NW possibly bringing storm activity as far South as Tahoe.  These storms would bring more significant precip than the past 2 storms.  The ridge will quickly try to rebuild off the coast by the weekend of the 17th.

In today's El Nino update from the NWS Sea Surface temps continued to cool.  Region 1+2 dropped to -0.3, region 3 to 0.6, region 3/4 to 0.7, & region 4 stayed steady at 0.8.  ONI which is the 3 month running avg. went up a tenth in Sept. to 0.8.  That is the 3rd straight month of El Nino conditions with temps 0.5 or higher.  2 more months for an official full-fledged El Nino.  SOI 30 & 90 day avg. is still positive.  SOI should be negative in a developing El Nino & always have in Sept. going into an El Nino winter.  The fact that this September they were positive is another reason to make it hard to believe that this El Nino will get very strong.  This weaks models continue to predict a moderate El Nino of 1.25 peaking by Dec.  I'm waiting for the Sea Surface temps to go up instead of down before I believe the El Nino will get even that strong.

The month of September had the temps in Truckee at 0.8 above avg.  That is only the 4th month of the last 26 months above avg.  September was a very dry month.  Only a few of the reporting stations have reported but so far the Lake Tahoe Basin is only 4% of avg. precip & the Truckee River Basin 1% of avg. precip.  September ended the 2009 water year.  As of right now the Lake Tahoe Basin ended the water year at 53% of avg. & the Truckee River Basin at 83% of avg. precip on the year.  This difference may be due to the storms coming into the PacNW this past winter & the areas North of the Lake getting more snow than South.  I should have the updated Donner Summit Snowfall chart that includes this past winter posted soon.  BA


Anonymous said...

hey, thanks for the update. Ive been reading this website for a while now. I appreciatte the information even though i dont completely understand the technical terms. keep it up! please give a summary of your predications at the end in like nontechnical terms though if you can thanks! :)

BA said...

I'll try to do that, thanks for the input. Also, on the new Home website I have a tools page if you want to try & look at what i'm looking at so it makes a little more sense.