Long Range Brings Another Arctic Front & Another Wave Snow Rain Next Week
You have heard me say very often that when you are in a weather pattern, weather events tend to repeat. Though they never repeat exactly they do have a tendency to rhyme. Since the beginning of the month we have been under the influence of a very strong negative East Pacific Oscillation.
What does this mean? This creates a jet stream pattern favoring cold air coming into the United States and in this case the cold air spreads into the east. You can thank the strong Pacific North America index pattern for that which makes a ridge in the Western Part of the US and a trough in the east.
These indices measure pressure change differences and are used to measure the strength of a certain pattern that sets up. In this case the large changes create a pattern that drive very cold air into the East. The negative pattern remains into next week though it does come off the lows.
Weather systems have been in the form of cold fronts coming through with cold air coming in behind it. The key to snow in the east is for cold air to arrive BEFORE the precipiation arrives with any developing wave. In today’s case the cold air arrives to late.
Monday we have another such “rhyming” system only this time, ate least according to the GFS model today, the front arrives first and the cold air builds in. When a wave develops on the front the cold air would be already in place and as the wave goes by on Tuesday we see snow all the way down the coast.
Would that it would be so simple! Weather models are struggling with this system (again). The European has been going back and forth on whether the the cold air gets in before the wave. Last night’s European model run suggested it would. Today’s suggest that it would be too late and most of the snow will be well to the north and west of the coast with the very cold air coming in behind it. Thanks to Pivotal Weather for use of the maps
Whether the wave is to far west or further east hinges on the upper trough. Both models are similar but the difference is the GFS is flatter and a little more progressive while the European is much deeper and less progressive and as a result further to the left.
We are likely to see models continue to move around for another couple of days so this is a long way from being resolved. Either way it turns very cold as polar air from Canada will spread into the Eastern US regardless. We still have lots to watch in the coming days.
MANY THANKS TO TROPICAL TIDBITS FOR THE USE OF MAPS
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