Global model runs discussion

[blp]

00z GFS out 192hrs high res portion and so far has nothing. No longer even develops the CV wave that it showed for several days. Looks like June out there. Absolutely perplexed by what is going on. . Just when we think we know all there is about storms we get a season like this to humble everyone.

http://www.tropicaltidbits.com/analysis/models/gfsfull/2013082900/gfsfull_pres_pcpn_atl_63.png

[South Texas Storms]

We FINALLY have a GOM fantasy land storm! Tonight's 0z GFS 384 hr forecast: http://www.tropicaltidbits.com/analysis ... atl_79.png

[Riptide]

Makes sense after a massive period of active years, regardless if there were no major landfalls. 2010,2011, and 2012 all had 19-20 named storms if I recall. The pattern may be in "recharge" mode.

[Alyono]

for more entertainment... at day 16... GFS has a cold front dropping through the Gulf... the modelcane then starts moving NE into the CGOM

[blp]

We FINALLY have a GOM fantasy land storm! Tonight's 0z GFS 384 hr forecast: http://www.tropicaltidbits.com/analysis ... atl_79.png

In a typical year we would have had 20 GFS fantasy runs like that by now with the system taking up half the GOM. maybe there is hope now.

[South Texas Storms]

We FINALLY have a GOM fantasy land storm! Tonight's 0z GFS 384 hr forecast: http://www.tropicaltidbits.com/analysis ... atl_79.png

In a typical year we would have had 20 GFS fantasy runs like that by now with the system taking up half the GOM. maybe there is hope now.

Yeah I know! I'm so surprised we haven't had many at all this year. It's good to see a fantasy GOM storm again

[ninel conde]

best looking wave of the season over africa now. somewhat surprised no model does anything with it.

[Blown Away]

GFS seems to continue developing a few waves coming off Africa and recurving them immediately with most runs not even taking these areas past 30W...Very weird season so far...IMO this will be a season the experts will have lots of discussions on what happened...

[South Texas Storms]

The 6z GFS still has the GOM fantasy storm in 384 hours. Maybe it's a sign the Gulf will be favorable for development in about 2 weeks.
http://www.tropicaltidbits.com/analysis ... atl_79.png

[PTrackerLA]

Looks like development of that GOM system starts about 11 days out. Something to keep an eye on as I have a feeling any US threats will come from in-close development this year IMO.

[blp]

Great blog today by Dr. Masters about research done by FSU researchers that classified the models by ability to predict genesis and false alarms. UKMET is one of the best at genesis prediction.

http://www.wunderground.com/blog/JeffMasters/show.html

[tolakram]

Great blog today by Dr. Masters about research done by FSU researchers that classified the models by ability to predict genesis and false alarms. UKMET is one of the best at genesis prediction.

http://www.wunderground.com/blog/JeffMasters/show.html

Wow, I would have never guessed. I'm taking a snippet out which I think is critical.

... The models have improved greatly in making genesis forecasts in recent years; back in 2007, when our top three models made a 4-day genesis forecast, these verified only 17 - 28% of the time. By 2011, the hit rate had increased to 45 - 50%. However, the models still miss most genesis events. In 2011, the probability of detection of a tropical cyclone genesis event was only 9% - 23%, meaning that 77 - 91% of time, a tropical depression or tropical storm formed without the model predicting that it would form. The best model to use for looking at Atlantic tropical cyclone genesis in 2011 was the UKMET model, which combined a relatively high probability of detection rate with a low false alarm rate.

...

Here's a direct link to that blog entry: http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2504


European ECMWF model: The model is reluctant to predict genesis, and misses many genesis events (it had only an 8% probability of detection in 2011.) However, when it does predict genesis, it usually happens, with only a 16% false alarm percentage in 2011.

American GFS model: The GFS model improved substantially in its genesis forecasts beginning in 2010, most likely due to a major model upgrade in 2010. The GFS is more aggressive at predicting genesis than the European model, and is less likely to miss a genesis event (22% probability of detection in 2011.) However, the incidence of false alarms was 32% in 2011

UKMET model: The UKMET is more aggressive at predicting genesis than the European model, and is less likely to miss a genesis event (20% probability of detection in 2011.) The incidence of false alarms was 18% in 2011

[CalmBeforeStorm]

Great blog today by Dr. Masters about research done by FSU researchers that classified the models by ability to predict genesis and false alarms. UKMET is one of the best at genesis prediction.

http://www.wunderground.com/blog/JeffMasters/show.html

From Masters' post.....

The study only looked at forecasts made up to four days in advance. While there have been cases where I've seen genesis predictions made 7 - 10 days in advance come true, these are rare, and the "hit" rate of successful genesis forecasts even four days in advance is low.

[tolakram]

From that article I visited the Tcgen page. Good stuff for short term tracking.

http://ruc.noaa.gov/hfip/tcgen/

For the area soon to emerge from Africa, the Euro has the longest plot.

[supercane4867]

952mb

http://www.tropicaltidbits.com/analysis/models/gem/2013082912/gem_mslp_pcpn_watl_38.png

[Riptide]

According that tropical genesis prediction study, one is more likely to witness a failed prediction of genesis than a successful prediction for all models; and by a large margin. More reason not to discount the central atlantic disturbance. The CMC (Canadian) had the highest rate of successful prediction but also the highest rate of false alarms.

[wxman57]

The NAVGEM was not included in the study, which only went through 2011 (no NAVGEM by then). Dr. Masters said that since the NAVGEM was based on the NOGAPS model that we might assume it may have some of the same problems.

[tolakram]

I just read through their docs (button on the top of the page). It's a slide show from a few years back prior to at least one upgrade. I'm not sure if the green dots and lines is a determination that a model is predicting cyclogenesis, or not. I assume it is, what else would it be there for, but not 100% sure.

[Riptide]

The NAVGEM was not included in the study, which only went through 2011 (no NAVGEM by then). Dr. Masters said that since the NAVGEM was based on the NOGAPS model that we might assume it may have some of the same problems.

Yeah, I got NAVGEM confused with the Canadian model, apologies.

[tolakram]

12Z Euro now to 240 not showing anything that really stands out, but it looks to be trying to develop another wave off of Africa in 9 to 10 days (fantasy range) as well as increasing the vorticity of what may be Pouch 25 near the Bahamas.