bdgwx

NCAR reanalysis is running warm too. In fact as of the 18th it is warmer than both Oct and Sep. It could be a photo finish on whether 2020 beats out 2016 on the GISTEMP record even despite the ongoing La Nina.

0Z SHIPS RI probability for 65 kts in 72 hours is 55%

I will say that GISTEMP came in at +0.90C for October which is 0.09C cooler than September. This lowers the odds of 2020 being the warmest. It's probably below 50% now.

HWRF, HMON, COAMPS, and experimental HAFS all have 98L attaining cat 4 intensity.

Hmm...maybe you're seeing something I'm not or perhaps your objection was regarding the method as opposed to the results but GISTEMP (which the Brown and Caldeira method is based) stands a reasonable chance of beating out 2016 still. We don't have the October value in yet but data from reanalysis leads me to believe that it could be elevated like the September value. And so far preliminary data for November is even warmer than October. Despite the La Nina I don't think we can confidently eliminate 2020 as being the warmest on the GISTEMP record yet. In fact, I'd say the odds are about 50/50 right now. Dr. Huasfather's analysis gives it an even higher 83% chance.

Yeah. It's something that is counter intuitive at first, but once you understand exactly how the GHE works and the fact that Antarctica has a unique vertical temperature profile it's pretty obvious it has to be this way. Unfortunately the negative GHE in this isolated region has its limits and will likely turn positive in the future here as well. Here is an interesting study that quantifies the effect. According to the authors most of the effect is actually attributed to water vapor which is a potent GHG itself. And it is the non-condensing GHGs (like CO2) that provide the secular nudge upward for water vapor concentration via the well known Clausius-Clapeyron lapse-rate feedback. https://www.nature.com/articles/s41612-018-0031-y Of course I don't mean to imply that the negative GHE is the sole or even dominant reason for the SH's weak polar amplification. Obviously many other factors are involved here with the most obvious being the larger percentage of ocean coverage relative to the NH.

Wow. Eta is definitely highlighting the problem with the CI number needing to be spooled in. ADTv9 has it clamped at 1.3T/6hr so it can't catch up with the raw value quickly enough.

A raw T# > 8.0 suggests a sub 900mb cyclone. I'll go 895 mb 150 kts.

ADT continues to show intensification. ADTv9 is at 5.4 at 21:20Z ADTv8 is at 5.8 at 21:00Z And based on the satellite presentation in the last hour I would not be surprised to see another tick up on these T numbers with the next update.

According to the best estimate from this study anthropogenic manipulation of the climate made the 2020 Siberean Heat Wave 100,000x more likely as compared to a purely natural evolution of the climate.

It's complicated. First understand that this is not entirely unexpected. In fact, the IPCC AR5 WG1 prediction for SH sea ice, although significantly more uncertain than predictions for the NH, shows a slight preference for increases through about 2030 with the possibility of record highs persisting even through 2060 before things turn south (pun intended) down there too. I must caveat that by saying the uncertainty envelope does include the possibility of the secular decline starting around 2020 as well. The unfortunate state of affairs with SH sea ice is that our understanding of its behavior in a warming world is still quite nebulous compared to our understanding of NH sea ice behavior. Second understand that the see-sawing of temperatures and sea ice between hemisphere has been shown to occur during previous significant climatic change events so it is not unprecedented nor is it inconsistent with climatic shifts. Anyway here are some things to consider... The NH is characterized by ocean surrounded by land whereas the SH is land surrounded by ocean. This trivial fact accounts for the bulk of the differences between NH and SH sea ice behavior. The consequences of this can be quite dramatic and contradictory between the NH vs. SH. A positive phase of the Southern Annular Mode (SAM) is associated with increasing SH sea ice. Global warming tips the SAM toward a positive phase. ENSO negative/positive phases reinforce positive/negative SAM phases. The Montreal Protocol through its ban of CFCs, repair of stratospheric ozone, associated cooling tendencies and other effects on weather patterns has been linked to SH sea ice increases. Increasing GHGs actually have a cooling effect on the Antarctica continent itself especially during the SH winter when the upper atmosphere is often warmer than the surface. Remember, GHGs act like a thermal barrier preventing IR radiation from passing through. This causes the warm/cool side of the barrier to warm/cool further. Positive/negative lapse rates get more positive/negative. Antarctica often has a negative lapse rate during the winter so GHGs cause cooling at the surface and warming in the upper atmosphere. This effect (among others) suppresses polar amplification in the SH. Disclaimer...I'm not well informed regarding SH sea ice so hopefully others who know more about the behavior down there can chime in on points I've missed or mischaracterized. The main take away here is that sea ice is mainly a NH issue right now. Most scientists do not expect NH-style declines in sea ice down in the SH anytime soon. And the fact that the SH responds differently than the NH is probably more the rule than the exception.

HWRF gets this down to 937mb at landfall near the Nicaragua/Honduras border...nearly the same spot as HMON.

Using a simple extrapolation I'm going to guess 10.18e6 km^2 for the 2020 annual mean. This would be 2nd lowest between 10.163 in 2016 and 10.201 in 2019. The current 3rd lowest figure is 10.335 so I still feel pretty confident that 2020 will end at least in the bottom 3. In fact, even if 2020's freeze trajectory catches up to the 1981-2010 mean by year end we'd still see a finish in the bottom 3. And if freeze rates continue to stay muted then a new record low for the annual mean extent is a definite possibility.

As of 10/20 the NSIDC extent YtD mean is 10.26. This is a tad higher than the current record holder set all the way back in 2019 at 10.23.. The gap is closing though. I think there is a good chance that 2020 will at least end in the bottom 3 in terms of annual mean extent. A new record is certainly a possibility as well.

As of October 13th the 5 day NSIDC average extent is at a record low again beating out 2012.