We will get this out of the way now. Don’t ask about snow. JOESTRADAMUS recognizes that the first flakes of the season will soon fall somewhere and we will leave it at that. However JOESTRADAMUS also has been watching developments carefully. All indications are that we are about to go into some sort of blocking pattern with a cool down beginning later this week as chilly air begins to advance from Canada. More than likely the first frosts of the season may be possible toward the end of next week given the set up aloft with the jet stream and the likelihood of troughing developing in the east. The map that follows is the upper flow for Wednesday.
To get a grasp of what is happening winds in the upper atomosphere blow from west to east but not all the time. When we get a set up like this where you see mountains (ridges) and valleys (troughs) in the pattern then the winds aloft blow from other directions. The black arrows show that the flow is northwest out of Canada so that is where our air is going to be coming from. If the winds were west to east the our air would becoming from the Pacific and across the United States which is a warmer flow. This is for Wednesday after another cold front moves through here late Tuesday which will begin the chill down.
By next FRIDAY. The northwest flow aloft is strong and still holding in place which will carry even colder air into the East for next weekend. Now on both the Wednesday and the Friday map I have singled out the low in the Eastern Atlantic that is pretty much in the same spot. This is very important to the overall long range pattern.
Now lets jump to day 10. This is important to the overall long range pattern. The GFS wants to go nuts developing a big blocking ridge just east of Greenland with the North Atlantic low pinned underneath. The ridge in the west is still there. The trough in the east is still there. Nothing really has moved. If anything the blocking has strengthened. Our air continues to flow out of Canada.
The implications here can go in a number of directions however this is what I think we can say at this point. After Tuesday of this week expect a cool down in temperatures with shot of cold air Friday into next weekend that is likely to bring the first frosts of the season to many areas. As far as storminess goes it does not appear that at least through the 10 day stretch that we could have an major events. Beyond day 10 is going to ultimately depend on the strength of that block and what it does. Usually the blocking highs migrate westward forcing the vortex in Canada further south. IF (and its a big IF) that happens then this could produce colder than normal temperatures for quiet awhile. As far as storm goes I would simply say that with blocking usually there is an opening for something storm wise to happen. But as always at this point everything is speculative. We can say that the pattern of the ridge of the east which was around through much of September is done with and that the weather is going to turn far more interesting over the next several weeks. In the meantime enjoy the holiday weekend which will finish warm with temps back in the 70s on Monday. It might be the last time we see 70 for awhile.
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