TS Cosme forms, expected tor strengthen further, Atlantic invest was almost a TC

By: wxchaser97 , 1:49 AM GMT on June 25, 2013

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Atlantic Invest
While this system occurred a few days ago, it is something that I want to touch on. Off the SE US coast, an area of low pressure formed. This was from a trough split that happened with a dying front. It only had marginal conditions to develop in. Wind shear was pretty high and surrounding pressures were high too, but the system was located right over the warm gulf stream. Thunderstorms were able to fire up and a broad, but closed, center developed. This system was becoming a tropical cyclone. Surface observations and T numbers indicated that this was nearing tropical depression strength, but it made landfall before it met all the criteria. Had this been over water for another day, we would've saw a TD, maybe even a TS. It brought rain and wind to parts of the SE, especially North Carolina. North Carolina was already. and still is, saturated, and any rain only adds to flooding problems. I don't expect this to be designated to a depression or storm during a post-season analysis since it didn't met all the criteria for classification. However, it shows that anything can try to spin up at anytime. A satellite image of the invest can be seen below.

TS Cosme
Tropical Storm Cosme formed this morning with the 2am PDT advisory. I believed we had a tropical storm at around 12-1am PDT when I did my last blog update. That was based on a blend of satellite appearance, SAB/TAFB numbers, and ADT numbers. Of course, the NHC had the same thoughts and Cosme was named with 40mph winds. He has been steadily strengthening throughout the day. A CDO structure has formed over the center of circulation and has persisted for a while now, with deep convection blowing up as well. Curved bands are also becoming more pronounced around the center, indicating a strengthening storm. With the strengthening center and CDO forming, there is likely an eyewall starting to develop. A recent microwave pass shows an eyewall is developing. Looking at ADT analysis, it shows a 65mph tropical storm. This is something that I can agree with. The latest ATCF update on Cosme that just came out confirms my thinking of a 65mph storm. The latest NHC advisory info and satellite image can be found below.

2:00 PM PDT Mon Jun 24
Location: 15.0°N 107.1°W
Moving: NW at 14 mph
Min pressure: 995 mb
Max sustained: 60 mph

Forecast for Cosme
Cosme has been strengthening all day due to very favorable conditions for intensification. I expect these conditions to continue for the next 36-48hrs. Warm ocean waters with decent ocean heat content means more than enough fuel for intensification. However, after 48hrs TCHP drops to zero and SST's drop below the 26C isotherm. This means Cosme won't have the necessary fuel to maintain strength or intensify. The air around TS Cosme is very moist. SHIPS analysis shows 700-500mb relative humidity values between 80%-90% for the next few days. Cosme has built a big moister shield because of the high humidity values. Convection has been abundant and dry air can't get near the center. These very moist conditions are expected to persist for the next couple days, and the air remaining moist for the full period. This means Cosme shouldn't have dry air cause intensification issues. Finally, wind shear isn't a problem for Cosme. SHIPS analysis shows shear staying low to moderate for the whole forecast period. This is because an anticyclone is situated over Cosme protecting it from any outside shear. This means convection has an easy time organizing over the center and the storm remaining vertically aligned. All signs point to an intensifying storm for the next 36 hours or so, and beginning to weaken after that. Since the storm is in a favorable environment for strengthening and it's using those conditions pretty fully, I expect to see hurricane Cosme in the next day. My intensity forecast is a blend between the SHIPS and LGEM, but leaning toward the SHIPS. As conditions get harsher at the end of the forecast period, I expect Cosme to turn post-tropical or even degenerate to a remnant low. While the peak intensity did have a decent jump upward, the current organization trends support a higher peak than what I had yesterday.

The forecast track for Cosme hasn't changed much from my last update. As the CDO has become situated over Cosme's center, it has pulled the center a little to the north. Cosme is still feeling the weakness to its northwest, so movement remains northwest. Global, dynamical, and statistical models still show the same pattern and track that they have been. Still expecting the ridge to expand and close the weakening to Cosme's northwest. This means Cosme will turn WNW and then eventually to the W. The flow around the ridge will be directing Cosme to the WNW and W as the ridge amplifies. My track is pretty well unchanged, besides the short term track a little farther north. TS Cosme shouldn't have much of a direct impact on Mexico, but some rain, waves, and rip currents are likely. Hawaii may receive some impacts too, but it is too far out to make any definitive calls yet.

INIT 25/0100Z 50 KT 60 MPH
12H 25/1200Z 65 KT 75 MPH
24H 26/0000Z 75 KT 85 MPH
36H 26/1200Z 80 KT 90 MPH
48H 27/0000Z 70 KT 75 MPH
72H 28/0000Z 55 KT 60 MPH
96H 29/0000Z 35 KT 40 MPH...POST-TROP/REMNT LOW
120H 30/0000Z 25 KT 30 MPH...POST-TROP/REMNT LOW

I'll have a new update on TS Cosme sometime tomorrow and an update on Atlantic development. Have a great night.
It's good to re-read your blogs before you post them. You may realize that you used guidance that wasn't the latest updated, which will mess up your intensity some.

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I'm in high school and love meteorology and extreme weather. I've been fascinated by weather since I was 5, and I plan on becoming a meteorologist.

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