Early SIR/CIR influence?

[MinYoongi]

Hello.

We've jumped from Kp1 to Kp5 due to what I assume to be an CH HSS, with a SIR/CIR ahead of it. Of course the next hours will tell, but I'm famously inpatient and would love your opinions, since the next CH HSS wasnt expected until Friday. What couldve caused the enhancement?

[Sam Warfel]

It's definitely a CIR.  I thought I saw space weather.com noting a chance for G1 today (swpc's call, not sw), it seems to be a tad early.

[KW2P]

Interesting. I was surprised. Late last night I checked the NOAA Kp forecast and it showed 1 or 2 for today so I was expecting fairly good radio conditions. Pulled up conditions today and Kp=5.  Haha.  So even the experts were caught off guard, apparently.

[Drax Spacex]

I cast my write-in ballot vote for "Stealth CME".

[lightpanther]

So what is the likelihood for a nontrivial Kp in about 3 - 4 hours time? (in rough and ready guesstimation of course).

Edited April 27, 2022 by lightpanther

[Sam Warfel]

3 hours ago, lightpanther said:

So what is the likelihood for a nontrivial Kp in about 3 - 4 hours time? (in rough and ready guesstimation of course).

Low, maybe 20% chance for KP4 or 5 

(That’s a rough and ready guess)

[MinYoongi]

20 minutes ago, Orneno said:

Low, maybe 20% chance for KP4 or 5 

(That’s a rough and ready guess)

Aaaaaand we're in Kp5.  

[Solarflaretracker200]

If it goes it KP7 (which I very much doubt) then I will be disappointed

6 hours ago, Drax Spacex said:

I cast my write-in ballot vote for "Stealth CME".

May I ask why you think this? I am not disagreeing with you nor agreeing. 

[Sam Warfel]

6 hours ago, Drax Spacex said:

I cast my write-in ballot vote for "Stealth CME".

I agree the solar wind speed jump was immediate and sharp, more like a CME than a CIR. The density had a big spike and then back down, that’s very characteristic of a CIR, although, granted, a CME might produce that too. But then look at the Bt. It actually dropped in strength dramatically when it arrived, it does not look at all like a CME. 

There’s room for debate, but I personally think it was a CIR 

[KW2P]

2 hours ago, Orneno said:

I agree the solar wind speed jump was immediate and sharp, more like a CME than a CIR. The density had a big spike and then back down, that’s very characteristic of a CIR, although, granted, a CME might produce that too. But then look at the Bt. It actually dropped in strength dramatically when it arrived, it does not look at all like a CME. 

There’s room for debate, but I personally think it was a CIR 

What do the aurora observers say?  My understanding is that a CIR causes big magnetometer swings, is very dangerous to spacecraft, is not dangerous to assets on the ground (electrical grids), and produces weak or no aurora. (I'm not arguing one way or the other.)

[Drax Spacex]

9 hours ago, Drax Spacex said:

I cast my write-in ballot vote for "Stealth CME".

Mainly because the anticipated CH HSS was not expected for a few days yet - and to brainstorm an alternative to stimulate discussion to better understand the differences in solar wind signatures for CIR/SIR, CME, CH HSS, etc.   SWPC called it a "transient feature" -  which encompasses a number of possibilities I would imagine.

[Sam Warfel]

The solar wind speed remains quite elevated, that looks more like a HSS than a CME to me