big winds in the models

01B.2023 MOCHA

I just noticed the super Rapid Intensification (RI) of the first storm in the IO -- 01B.2023.

NB: I add the year of the season to the NNB ATCF ID because the 2023 SHEM season starts 1 July 2022. NN is the JTWC storm number and B is the subbasin id for the Bay of Bengal.

Here's a plot of the track from 01B.2023 origin as pTC (pre/potential TC) 91B from 2023050712-2023051012.  The first JTWC warning was issued on 2023051018 with an intensity of 30 kts -- what I define as genesis.  It is currently 14UTC 14 May 2023 (2023051414)...

01B.2023 MOCHA track 2023050712-2023051412.  The TC was a pTC (91B) from

The plot below comes from the site I set up for JTWC (and NHC) to visualize the 'diagnostic file' (input to the statistical-dynamical intensity prediction aids, e.g., SHIPS) https://jtdiag.wxmap2.com.  

The main purpose of the JTDIAG site was to move the model forecasts forward in time to the same time as the warning cycle, e.g., the 18 UTC 14 May 2023 (2023051418) warning will be issued around 20:30 UTC 14 May 2023 (+2:30 h after synoptic time).  The site also displays the sea-level pressure with a direct calculation of the ROCI (Radius of the Outermost Closed Isobar) from the lat/lon of the contour (a pretty slick GrADS trick).

What caught my attention was the 140 kt forecast of the Navy global model (NAVGEM)!  This is the first time I've seen such a big wind from a model tracker. 

plot of surface wind for the 72-h forecast from 2023051018

Focusing on the table with the max winds:

we see the 140 kts at tau 72 h for NAVGEM.

I've seen the ECMWF produce winds > super Typhoon (130 kts), but not other models.  Note that the GFS winds at 72 h are 102 kts...

Digging a little deeper, here is a plot of the operational trackers for 2023051018; the time of JTWC's first warning.  

NB: I am using the uninterpolated model trackers for HWRF/GFS/NAVGEM. The ECMWF forecast comes from local tracking using full-res ECMWF fields...

2023051018 model tracks for HWRF/GFS/NAVGEM/ECMWF

Both NAVGEM and HWRF correctly forecast the Rapid Intensification (RI).  The errors with GFS & ECMWF are not as good intensity wise -- slow and smaller -- but still forecasting the storm would become intense.

Going back 12 h...

2023051006 model tracks for HWRF/GFS/NAVGEM/ECWMF

NAVGEM made an even bigger forecast of 147 kts!!  And the 4-day HWRF forecast for both intensity and track are outstanding! Or as the British would say 'spot on.'

One of the benefits of this quick and dirty analysis is that I found some 'features' (i.e., bugs) in my codes (as Rosanne RosannaDana would say: "If it ain't one thing it's something else.").  

The original plots contained a 150 kt best track intensity for 2023051400 that was not consistent with the real-time intensity on other sites such as CIRA https://rammb-data.cira.colostate.edu/tc_realtime/index.asp. The reason for the difference is that the latest JTWC 'bdeck' (best track) has 150 kts for 2023051400 position and I had inadvertently used the bdeck (bio012023.dat) vice the 'adeck' (aio012023.dat) with the real-time positions used by the models (the so-called 'bogus' file)

01B.2023 is a remarkably TC especially in how well the models performed in directly forecasting the RI.

Other sites that might be of interest:

• weather maps
• TC genesis

Comments and questions always welcome.