Wednesday, 10 October 2012

Long Ranger: MJO says wet pattern for Great Lakes

The MJO will be headed away from the COD and into a high amplitude phases eight and one. Here are  various forecasts from a few models.



If we look at phase 8 and 1 in october we can see a very wet pattern across the great lakes, ohio valley and the northeast. In phase 8 the wetness will be further west across the upper great lakes and parts of the midwest. In phase one the wetness spreads further south and east into most of the eastern two thirds of the u.s. B.C and the pacific northwest will get in on some enhanced precipitation as well as the northern jet supplies some precipitation and more systems barrel into Alaska(-PNA pattern develops).

There is support on most of the modelling for a strong system in this time period with warm air advection out in front of it and a SW flow of air bringing above normal temperatures for the east. Less cold air will penetrate the east as this system moves out because the source region will be a pacific airmass instead of an arctic airmass like we are experiencing with our current trough. Notice the very strong cold front associated with this and the potential for a severe weather outbreak. In my opinion it will be a small outbreak and lower then current expectations by some. The pre-existent cold air mass will limit a large temperature gradient from setting up and lower dew points will develop in front of the cold front. Nonetheless, any October severe weather outbreak is impressive as we are in between the two main severe weather seasons.

Going further down the road, Phase 8 MJO precipitation correlates well with the impressive precipitation field and a classic comma shape configuration shown on the 18z GFS at hour 192. The look of this system reminds me of what the groundhog day blizzard looked like on february 2nd 2011 except it is 2 months early. If this were to occur in december then we are in business for big snows in the east. This may be a sign of a more inland track this winter as well as the classic east coast phaser with a ridge axis centred over the rockies.

 Another interesting thing to take note of is a more active northern jet in the long range with more arctic air masses available and small pieces of the main western trough breaking off and moving eastwards getting departures down and setting up a very active and interesting pattern for the east.

No comments:

Post a Comment