ideas on why eastern heat ridges keep going to canada?

[HeatMiser]

I've noticed over the past couple weeks, the model runs will suggest an eastern US ridge developing, and then as we get closer it continues to move further north and up into Canada. Given southeast drought conditions and the warmer SSTs off the coast right now, I would think that would help keep the heat further south along the coast.

Any thoughts or ideas on this? Seems the heat we get now is either in canada, or upper midwest near the great lakes.

[isohume]

It's a dynamical response to the persistent north atl anomalous low or -NAO, which has maintained a general blocking low pressure trof across the ern CONuS. Meanwhile...NW CONUS heights continue to periodically drop (normal Rosby wave propagation) and impinge upon the mid-continent ridge. Thus, the ridge has had nowhere to go but north into Canada.

The models can have a hard time breaking down blocking patterns such as the one in place now. Back on my last operational shift, ~2 weeks ago, the models where breaking down the north atl block and moving things along in a few days...when in fact the atmosphere has been reloading the same pattern at the higher latitudes the whole time since.

[HeatMiser]

So, essentially the ridge is getting squeezed from both sides. And while the models are not picking up the -nao blocking in the longer term, it is seeing the western trough, am I understanding that correctly?

Thanks for the help.

[isohume]

Yep. that's essentially it. The ridge is being dynamically forced northward. The models generally don't "like" stagnant situations in the mid-latitude westerlies. Models are time derivative, which means they change things with time (ie: delta-T in the denominator). Therefore, moving Rosby waves are usually handled more accurately than blocking features.

[Sunny and Warm]

It should also be noted that the SE USA has seen copious amount of rain lately, thus negating some of the base conditions in your original statement. In fact, June looks to be cloudy, damp, and cooler than average in these parts.

[HeatMiser]

good point on the rain front. Looks like this sunday through next week will be quite wet as well in the southeast which will improve drought conditions.

[NJwinter23]

Great stuff isohume...sure enough, the trends today have been to slip an ULL under ridging that shoots north and across the Davis Straights/Greenland region for the 6-10 day average...this is making the end of next week look a lot cooler for the east coast/Midwest than thought in recent days..and in my opinion it is legitimate when considering the MJO going into phases 6-7 (correlates well to nao blocking in june)

[Sunny and Warm]

Great stuff isohume...sure enough, the trends today have been to slip an ULL under ridging that shoots north and across the Davis Straights/Greenland region for the 6-10 day average...this is making the end of next week look a lot cooler for the east coast/Midwest than thought in recent days..and in my opinion it is legitimate when considering the MJO going into phases 6-7 (correlates well to nao blocking in june)

Wondering if this becomes the predominate regime this summer (NAO blocking). Isn't that a tendency while still under the waning influence of a Nina?