Windy…Cooler Today with Cold Front flushing through by the end of the day….Upslope Snowshowers Thursday…Chilly weekend…..
Wednesday November 30, 2011
Posted at 9:39 am by Howard
New 12z EC run now follows the GFS lead by taking the 2nd short wave further east. So no strong reinforcing shot of cold air expected this weekend. However with that said, it will be plenty cold to make snow.
Just a quick update:
Cold Front moving very quickly southward. It passed Tahoe at 15z. It should clear the central sierra by early afternoon. Some showers possible this afternoon but far and few. Winds will highlight the day with gusts 30 to 40 in town today. Temps have already peaked for the day.
Expect some upslope developing after midnight then through Thursday. It will be cold Thursday with highs in the mid 20s….and Wind chills in town from 0 to 10 above at times.
The convective area of MJO is over the Indian ocean at about 70E. It is in a position that would be conducive to a negative PNA…however, as of late, the teleconnection has been weakly positive to neutral.
As you can see….The current forecast for the teleconnection is for a negitive PNA over the next week.
Furthermore…the dynamic MJO Forecast shows a strong progression into Phase 4.
Between 70E and 120E is where we would expect the negative phase of the PNA. IE West coast trofing associated with the MJO and -PNA.
So over the next few days….look for retrogression in the long wave high over the eastern pac, if the MJO is going to have an effect, as beyond 120E the PNA usually trends Positive again.
What are the models showing during week 2?
The latest deterministic 12z run of the GFS has the current position of the long wave ridge centered at 135W. By Dec 2nd it retrogrades to 140west. Further retrogression occures to 143W on the 6th of Dec which then retrogrades the short wave track westward back over California….. which is still over land. Further retrogression is suggested but not conclusive. So…..We are still waiting to see….
Reference Glossary of Weather Terms
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