Tuesday, 15 January 2013

Eastern Storm Threat Possible Jan 23-27

I am watching a potential storm in the 7-12 day period for the eastern seaboard. This threat lines up with the current low pressure bomb in the west pacific which usually telleconnects with an east coast storm system 7-11 days later. Although this storm will not be nearly as strong in the u.s, a significant system is possible on the east side of the trough that will deepen after the 20th of janaury.
Heres our west pacific storm:

Lower heights to the west of japan telleconnect with a trough centered over the great lakes region around the 22nd. A storm should form on the southeast side of the trough but phasing of jet stream disturbances are very difficult to forecast this far out and will change on the models. Track of the storm will be hard to pin point for several more days as models have trouble handling these disturbances but I want to warn eveybody about this threat. The european model is showing this storm developing at hour 240. Important to note is the classic banana shaped high which will help keep the cold air in place. Also important is the lack of a well defined 50/50 low which will limit downstream ridging and speed up the system. These details will have to be ironed out over the next week and will be crucial to the track of this system.
With plenty of cold air available to the north this storm should track along the baroclinic boundary with the large thermal gradient setting up near the eastern seabord. To see where this might set up lets have a look at the h5 pattern predicted by the european ensembles. Notice the west based -NAO blocking which will allow the storm to track further east. A SE ridge is present although shifted further south which may allow this storm to track further NW.
To sum up here are some keys points that I want to mention:
1. A significant storm is possible for the eastern third of the nation between the 22-27 of Jan
2. Track and strength of this system is very unceratin until we get closer to the event
3. Pleny of cold air should be present NW of the storm center
4. Phasing of jet disturbances, 50/50 low and -NAO positioning will be key
If you have any question or comments feel free to ask as always!

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