Severe Weather In Trouble as Guidance Backs off!

You read that headline correctly. Models are beginning to back off on the threat of a severe weather outbreak! CAPE that at one point and time was showing some astounding #s is now not at the same level.

If you remember we talked about the question of whether or not the CAP would be able to be broken. It appears as if the answer to that is most likely not and if and when it does break it appears it would be on Wednesday-another thing we mentioned. This does not mean that severe weather will not happen prior to then it just means its going to be limited to a smaller area and slow to occur.

So lets begin this update by looking at the teleconnections which are in place and being projected out in time.

North American Oscillation

You can see the the NAO is negative and pretty much expected to stay negative to neutral negative at the very best.

Arctic Oscillation is neutral negative and you can see is relatively expected to stay negative and some members of the means are even showing it to start to bottom out. Now understand this if this was still winter time we would be looking at much below normal temperatures with these two connections showing the way they are.

The Pacific North American Index or the PNA. Members are divided here as some are showing negative (which it is currently) and some are showing it going positive. A positive PNA would indicate a trough on the east coast and a ridge out to the west.

So what does this all mean in relation to the sensible weather? Essentially it would mean that any ridge attempting to build into the Northeast is going to be met with resistance. Why? Negative NAO and a negative AO and a Positive or at the very least Neutral PNA (cause members are divided on that) would indicate that a trough is going to be hanging tough over the Northeast part of the region and help to keep things on the cooler side of the equation.

Now lets turn to the models and see what is happening..

This is the European Computer model for 72 hrs out. Couple things i pointed out on the image. One you see the ridge and the warm southerly flow trying to push northeast. Two , you see the trough over the NE and a area of low pressure off the Northeast coast. Cooler air flowing down from the North into the Northeast. Now lets watch what happens..

Now, we are out 120 hours. Notice how the ridge really has not made any progress towards the NE? Notice how the trough is still lingering over the NE?

Now at this point above some headway is being made. We are now up to 144 hrs. However, notice the low pressure to the west? Watch what happens.

That low pressure to the west reforms another low off the coast and right back into the trough along the east coast and the ridge never is allowed to build into the region. Is it correct? A little to early to say. Does it make sense teleconnections wise? Completely. Now watch what happens with the new low in the midwest!

Last image had some kind of malfunction but that area of low pressure sinks south and becomes cut off and forms a HUGE trough over the east and central part of the states. High temperatures on the 15th and 16th of May are shown to be only in the 50s in the Northern Mid Atlantic region and Northeast.

While there is some minor details mainly with Shortwave placements etc you will see that the GFS essentially agrees and never really gets the warm air into the NE or Northern Mid Atlantic (the exception being W PA due to over strengthening the first low pressure that cuts west)

So, what does this mean as far as the severe weather is concerned? With the CAP in place this means that any severe weather before wednesday is going to be limited and slow to occur. Then when some more favorable dynamics come into play it will keep the severe weather off to the south and the west of the Mid Atlantic region and likely to be further north then last time around.

It also means that Flooding potential increases where ever the cut off low decides to set up shop which ATM looks to be over the Southeast and cooler weather looks to pretty much dominate the pattern over the next 10 days.

Stay tuned for more information including an updated outlook for severe chances tomorrow!