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Chasing RINA


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You learned an important lesson with Rina. When dealing with Tropical systems, the low level remnants can still produce sensible weather. The low level vorticity can generate low topped and medium topped convection which can give rainfall through the warm rain process (which is how you can get rain in the Tropics without any freezing in the clouds). The still present gradient plus the downdrafts from the warm convection can still generate 20-25 kt sustained winds and gusts in the 30-35 kt range-nothing spectacular but still a TC experience. We saw this with Ismael in 1995 and Isis in 1998 (q: why name an EPAC storm after an Egyptian Goddess?). The low level circulations sheared apart from the mid level as the storms moved inland with the LLCCs moving into AZ and the mid levels into NM where they got a sh**tload of rain. Yet the LLCCs still generated rain (Ismael especially in Cochise County which surprised the NWS in Tucson where they had nothing). The fine droplets common to warm rain but heavy enough to bring notiiceable amounts. The attached video frame capture shows the cloud cover from Ismael with a rainband to the north that was approaching us as the LLCC passed east of us.

post-92-0-19236400-1319844731.jpg

Steve

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You learned an important lesson with Rina. When dealing with Tropical systems, the low level remnants can still produce sensible weather. The low level vorticity can generate low topped and medium topped convection which can give rainfall through the warm rain process (which is how you can get rain in the Tropics without any freezing in the clouds). The still present gradient plus the downdrafts from the warm convection can still generate 20-25 kt sustained winds and gusts in the 30-35 kt range-nothing spectacular but still a TC experience. We saw this with Ismael in 1995 and Isis in 1998 (q: why name an EPAC storm after an Egyptian Goddess?). The low level circulations sheared apart from the mid level as the storms moved inland with the LLCCs moving into AZ and the mid levels into NM where they got a sh**tload of rain. Yet the LLCCs still generated rain (Ismael especially in Cochise County which surprised the NWS in Tucson where they had nothing). The fine droplets common to warm rain but heavy enough to bring notiiceable amounts. The attached video frame capture shows the cloud cover from Ismael with a rainband to the north that was approaching us as the LLCC passed east of us.

Steve

Hey, Steve!

Yeah, it was actually a cool learning experience. I was quite surprised at what a solid, vigorous cyclone structure remained at the surface-- especially those backside winds. (As you know, people tend to overestimate the winds they experience, and I think a lot of folks don't realize how strong a steady 25 kt is.)

Thanks for explaining the physics behind it. It's good for me to understand a little bit of the dynamics with this-- even if the whole idea of decoupling vortices is disturbing and unpleasant to me. :D

P.S. You guys had a lot of Desert-SW tropical action in the 1990s, it seems like.

P.P.S. Yeah, I've wondered about Isis, too. :lol: Such a totally random name for a cyclone basin that almost exclusively impacts Spanish-speaking countries.

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Well, I live in L.A., which is very Mexican, and I don't know any. :P

How do you pronounce it-- "EE-siss"? (It wouldn't be "EYE-siss" like we say it, I wouldn't think...)

Yep, it's pronounced Isis as it is spelled ;) .... (EE-siss). Probably the sample of mexicans i know is greater than yours....just maybe :P

There's an easy experiment... google Isis and whatever hispanic popular last name you know (Gonzalez, Rodriguez, Perez, Hernandez, etc)...there should be an Isis for all of them.

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WRT Josh's PS-yes we did get a lot of remnants (and actual storms) in AZ in the 1990's-actually starting in 1986. A partial though nearly complete list follows

1986: Newton-NHC finalled this one as soon as it made landfall near Los Mochis but the remnant was at least TD and possibly TS when it passed over Douglas. Gusts to 64 mph were recorded near the Huachuca Mountains-NM got dumped on.

1989: Raymond was a Minimal TS or strong TD when it passed over FHU 3-6 inches of rain in Sierra Vista and 60 mph gusts off the mountains

1992: Lester: Defintely a TS as it passed 20 NW FHU gusts to 78 mph near the mountains, 60-70 mph gusts in the valley and 56+mph gusts east of Benson 3-8 inches of rain

1993: Hilary: TD into SW AZ Tornadoes in SE AZ

1995 Ismael: As described above gusts to 40 mph near the mountains around 30 elsewhere

1997 Nora: TS near Yuma gusts to 60 mph and 12+ inches of rain in Mountains causing flooding.

1998 Isis: Mentioned above LLCC passed south of FHU over TUS and into NW AZ moderate rains southern AZ heavy rains northern AZ

2000: Olivia: Mid level remnant passed through Cochise County and western NM HEAVY rains in mountains and gusts over 30 mph in squalls.

2001 Juliette: Dissipating TD heavy rains in western Pima County gusts to 30+ mph Sierra Vista and 51 mph near Tucson

2003 Marty: Dissipating TD heavy rains southern AZ

2004 Javier: LLCC passed over Sierra Vista moderate to heavy rain

2007 Henriette: Mid level remnant in eastern Cochise County and western NM heavy rains and flooding at least one fatality

In 1995, the post trop remnant low of Juliette was picked up by a ULL off the CA coast, as the system tracked into the Sea of Cortez it tried to redevelop but merged with a front as it entered AZ. a massive severe weather outbreak occurred in AZ with confirmed baseball hail near Tucson (unconfirmed softball hail and possible tornadoes) and tennis ball hail and gusts to 84 mph causing widespread damage on FHU. This happened on the night of my Birthday and was my last storm on Post as I retired three days later.

Yes a sustained 25 kt wind is rather breezy when one consider that it's just shy of 30 mph.

Steve

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WRT Josh's PS-yes we did get a lot of remnants (and actual storms) in AZ in the 1990's-actually starting in 1986. A partial though nearly complete list follows

1986: Newton-NHC finalled this one as soon as it made landfall near Los Mochis but the remnant was at least TD and possibly TS when it passed over Douglas. Gusts to 64 mph were recorded near the Huachuca Mountains-NM got dumped on.

1989: Raymond was a Minimal TS or strong TD when it passed over FHU 3-6 inches of rain in Sierra Vista and 60 mph gusts off the mountains

1992: Lester: Defintely a TS as it passed 20 NW FHU gusts to 78 mph near the mountains, 60-70 mph gusts in the valley and 56+mph gusts east of Benson 3-8 inches of rain

1993: Hilary: TD into SW AZ Tornadoes in SE AZ

1995 Ismael: As described above gusts to 40 mph near the mountains around 30 elsewhere

1997 Nora: TS near Yuma gusts to 60 mph and 12+ inches of rain in Mountains causing flooding.

1998 Isis: Mentioned above LLCC passed south of FHU over TUS and into NW AZ moderate rains southern AZ heavy rains northern AZ

2000: Olivia: Mid level remnant passed through Cochise County and western NM HEAVY rains in mountains and gusts over 30 mph in squalls.

2001 Juliette: Dissipating TD heavy rains in western Pima County gusts to 30+ mph Sierra Vista and 51 mph near Tucson

2003 Marty: Dissipating TD heavy rains southern AZ

2004 Javier: LLCC passed over Sierra Vista moderate to heavy rain

2007 Henriette: Mid level remnant in eastern Cochise County and western NM heavy rains and flooding at least one fatality

In 1995, the post trop remnant low of Juliette was picked up by a ULL off the CA coast, as the system tracked into the Sea of Cortez it tried to redevelop but merged with a front as it entered AZ. a massive severe weather outbreak occurred in AZ with confirmed baseball hail near Tucson (unconfirmed softball hail and possible tornadoes) and tennis ball hail and gusts to 84 mph causing widespread damage on FHU. This happened on the night of my Birthday and was my last storm on Post as I retired three days later.

Yes a sustained 25 kt wind is rather breezy when one consider that it's just shy of 30 mph.

Steve

AZ has had a little more action than I realized. OK, I have new respect for these dying systems in AZ. I have to admit, I've often dismissed them. :) So Raymond, Lester, and Nora sound like the best ones for AZ-- however, your birthday storm sounded particularly awesome-- like a retirement gift. :wub:

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Here's a chase map and two graphs of my data:

*A barogram from the time I was at a fixed location (in Palmul). The NHC indicated the center was near this location at 10 pm CDT, but according to these data, it passed through around 9 pm. The lowest pressure (996.5 mb) corresponds nicely with the recon value of 996 mb.

* A wind trace for the hour that I took measurements-- from ~10 pm to ~11 pm CDT. This was a period of suddenly vigorous winds-- blowing from the SW-- after the center/lull passed. During this time, I stood on the beachfront patio holding the Kestrel over my head (yes, continuously for an hour-- my arms were aching from it). The sample rate was 30 secs, which is very low-res for wind data-- a lot is missed. The patio was slightly elevated, so the height of the instrument was ~4 m; the winds were of course higher at the standard 10 m. These winds are nothing to write home about, but they show that Rina still had tight, vigorous surface circulation at this time. The highest winds at landfall occurred not where I was, but E of the center, in the vicinity of Cozumel.

Don't try to match the two graphs vertically-- they're showing very different sample periods! The barogram is a ~3.5-hr period, whereas the wind trace is just for ~1 hr within that time.

post-19-0-43312900-1320035987.png

post-19-0-74921300-1320006768.png

post-19-0-87178800-1320006778.png

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AZ has had a little more action than I realized. OK, I have new respect for these dying systems in AZ. I have to admit, I've often dismissed them. :) So Raymond, Lester, and Nora sound like the best ones for AZ-- however, your birthday storm sounded particularly awesome-- like a retirement gift. :wub:

BTW, I didn't list the ATLANTIC basin remnants from storms in the western GOM some of which were really wet.

Steve

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  • 2 months later...

The NHC released the Rina report: http://www.nhc.noaa....182011_Rina.pdf

Well, the chase was a bust but it's cool that my data had some value in postanalysis. They actually adjusted the landfall time one hour earlier-- from the operational 0300Z to 0200Z-- to match the time of my lowest pressure at the landfall point in Paamul (see the second-to-last paragraph in Meteorological Statistics and Table 2). My low pressure (996.5 mb at 0212Z) corresponded with the recon quite nicely.

That almost makes the the chase worth it. :D

An interesting tidbit about the report: Rina was upgraded to Cat 3 in postanalysis.

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