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Tropical weather analysis - October 23, 2013

By: KoritheMan , 6:10 AM GMT on October 25, 2013


Tropical Storm Raymond is intensifying again. As of the latest NHC advisory, the following information was posted on the storm:

Wind: 60 mph, with higher gusts
Location: 14.6°N 107.7°W
Movement: W at 10 mph
Pressure: 998 mb

After its rather abrupt weakening episode the other day, Raymond has made a significant comeback this evening. Although the cloud pattern is still a little ragged, there is a somewhat broken curved band to the west. Satellite estimates range from 3.5 from TAFB to 3.0 with SAB, and an objective UW-CIMSS ADT estimate gave 55 kt. Based on the cloud pattern and the lack of a distinct inner core in the latest microwave images, I prefer the lower end of the satellite estimates.

Figure 1. Latest infrared satellite image of Tropical Storm Raymond. Image credit: NOAA's Satellite Services Division (SSD).

Upper-level outflow has expanded significantly to the west, indicating that the upper flow has transitioned from southwesterly to a more favorable southeasterly. While the upper air environment seen on the GFS model is not the most anticyclonic I've seen, it does appear to at least be diffluent and of fairly light shear. This pattern should allow Raymond to reintensify, and my forecast calls for the cyclone to regain hurricane strength in about 48 hours, although there is a chance it could occur a little sooner. By day four, southerly shear is forecast to increase ahead of a large upper-level trough digging over the eastern Pacific west of Baja California, and Raymond is anticipated to respond by weakening; the environmental airmass will also become drier at that point as sea surface temperatures begin to cool.

Raymond's center has been very difficult to find, and my personal position (shown below) was based heavily on extrapolation of the position given from the 0300Z NHC advisory. It has been equally hard to determine which direction Raymond is moving, but based on the environmental steering flow seen on UW-CIMSS steering data, a south of west motion may be the best estimate. The global models show the rather strong subtropical ridge anchored to the north of Raymond expanding westward ahead of the storm over the next few days, which should cause Raymond to move west-southwestward and then westward as the ridge stabilizes. Guidance is in good agreement on the track out to three days. While there remains some divergence thereafter, in general the guidance continues to trend toward the trough being strong enough to capture Raymond. My forecast will do the same, although will be a little more conservative in pulling Raymond up into the southwesterly flow connected to that trough until I can more confidently determine how strong the trough is going to be at those large timeframes.

It is unlikely Raymond will be a tropical cyclone of any kind if the trough somehow captures it and sends it to Baja.

Intensity forecast and positions

INITIAL 10/25 0600Z 14.5°N 107.8°W 50 KT 60 MPH
12 hour 10/25 1800Z 14.3°N 109.6°W 50 KT 60 MPH
24 hour 10/26 0600Z 14.1°N 111.1°W 55 KT 65 MPH
36 hour 10/26 1800Z 13.8°N 112.8°W 60 KT 70 MPH
48 hour 10/27 0600Z 13.6°N 115.2°W 65 KT 75 MPH
72 hour 10/28 0600Z 13.9°N 118.3°W 75 KT 85 MPH
96 hour 10/29 0600Z 14.7°N 119.7°W 75 KT 85 MPH
120hour 10/30 0600Z 16.3°N 119.9°W 60 KT 70 MPH

Track forecast

Figure 2. My forecast track for Raymond.

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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3. WunderAlertBot (Admin)
4:59 AM GMT on October 26, 2013
KoritheMan has created a new entry.
2. KoritheMan
6:22 AM GMT on October 25, 2013
Quoting 1. Astrometeor:
Lee Grenci all but called the rapid weakening of Raymond due to upwelling of cold waters. And I thought Raymond was on the verge of having an early death at one point.

Thanks for the update!

I had anticipated upwelling would be a factor about a day before it was explicitly considered by the NHC, but I still didn't expect the extreme weakening that followed.
Member Since: December 31, 1969 Posts: Comments:
1. Astrometeor
6:15 AM GMT on October 25, 2013
Lee Grenci all but called the rapid weakening of Raymond due to upwelling of cold waters. And I thought Raymond was on the verge of having an early death at one point.

Thanks for the update!
Member Since: December 31, 1969 Posts: Comments:

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Basement-dwelling pseudo-otaku with a thrill for forecasting on the side.

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