Wednesday, November 7, 2012

Thanksgiving Likely to be Cool, Wet as MJO Shifts

Forecasted MJO off the NCEP

Precipitation anomalies in Phase 1 of the MJO. Green is above normal,
brown is below normal.

Temperature anomalies in Phase 1 of the MJO. Blue is below normal,
orange is above normal.
The time period close to Thanksgiving is looking cool and wet after an expected warm-up in coming days as the Madden-Julian Oscillation, or MJO, cuts around to Phase 1 by the last 2 weeks of November.

The MJO involves convection in the Indian Ocean/Pacific Ocean. The phases are determined by placement of precipitation, and each phase has a different effect on the United States. Phase 1 is typically considered among the best phase for snow lovers in the winter, as it is known to incite below normal temperatures and above normal precipitation across the central and eastern regions of the Lower 48.

If you have been watching my posts recently, you may have heard me mention something called the Rossby Wave. It involves storm systems moving south from the North Pole over the general same area. This time, the Rossby Waves will be in place over the West US, which will likely bring about warm conditions in the East. However, the good thing about Rossby Waves is that they are not persistent storm systems, meaning they hit the area they are supposed to, and then leave before another one takes its place. This, in turn increases the storm activity over the nation in this scenario.

If I use the MJO, Rossby Waves and my LRC winter forecast, I find it possible for the Midwest, Ohio Valley and Northeast to be up against a fairly strong storm system on Thanksgiving.



KakHome said...

Andrew - What do you estimate for departure from normal for November in Cleveland?

Also though they are not cold, the models don't show truly warm air in the East once this weekend/early next week is done with. Do you expect another big Eastern ridge shortly behind the one about to come, or do you feel it is possible that this weekend/early next week will be the only truly *big* warmup?

Anonymous said...

Andrew-if the northeast is supposed to have a big storm during thamksgiving then why does it say that new york city and philly and going to have below normal precip. thanks

Anonymous said...

What would this mean for the central plains? I know its much too early to tell but could the plains possibly have the instability factor when this next system comes through around the 21st.?