Tropics Bursting With Life

By: MAweatherboy1 , 9:05 PM GMT on October 11, 2012

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Despite the peak of the season being past us, there is a lot of tropical activity in the Atlantic, and the world, this evening. The biggest feature in the Atlantic right now is newly named Tropical Storm Patty. Patty currently has maximum 1 minute sustained winds of 40mph and a minimum central pressure of 1007mb. Patty is currently located 255 miles NE of the central Bahamas and is stationary.

Forecast for Patty
Patty does not have a long life ahead of it. Upper level conditions over Patty right now are marginally favorable, and I would not be surprised to see her strengthen another 5mph or so in the next 12-24 hours. However, beyond 24 hours, the already moderate shear will increase and tear the system up. Dissipation should occur in no less than two days and it may happen before then. Patty is a very interesting system as practically no one, including myself, thought it had any real chance of developing when it was first classified, and even by last night when it had remained organized for a while, the prospects for classification still looked bleak. I am looking forward to Patty's Tropical Cyclone Report after the season ends, which will hopefully shed some light on exactly how she developed and what the NHC was thinking as they tracked her precursor disturbance, 97L.


Figure 1: Tropical Storm Patty.

98L Likely to Develop
Also in the Atlantic, large invest 98L has been slowly but steadily organizing as it approaches the Caribbean. The National Hurricane Center gives 98L a 50% chance of developing in the next 48 hours. I agree with this percentage, but give the system an 80% chance of developing at some point in its life. 98L is currently located near Barbados, and is moving slowly NW. This motion is expected to continue, and 98L will likely brush the NE islands of the Caribbean. It is unlikely to be a strong system as it does this, but it will provide locally heavy rain nonetheless as it is a large disturbance. Beyond this time I am thinking that 98L will strengthen more, and likely recurve well east of the US. It is possible Bermuda could eventually see impacts but it is too early to know for sure right now.


Figure 2: Invest 98L.

97E May Develop
In the East Pacific, an area of disturbed weather, invest 97E, is currently located about 550 miles S of Manzanillo, Mexico. 97E has slowly organized over the past couple days, and it is currently being given a 40% chance of developing in the next 48 hours by the NHC. I put these odds slightly higher at 50%, with a 70% chance 97E develops at some point in its life under fairly favorable upper level conditions. 97E is slowly drifting west, further away from the Mexican coast, so it should not be a threat to land.


Figure 3: Invest 97E.

Prapiroon A Threat To Japan
The main feature in the West Pacific right now is Typhoon Prapiroon. As of the latest advisory from the Joint Typhoon Warning Center, Prapiroon has maximum 1 minute sustained winds of 95kts, making it a high end Category 2 equivalent on the Saffir Simpson Scale. Prapiroon is currently located about 400 nautical miles south of Kadena Air Force Base, Okinawa, and is crawling NNW at 3kts. It is soon forecast to take a hard NE turn, but not accelerate significantly. Then, after about 3 days, it is actually expected to turn back to the north. This is extremely unusual as you almost never see storm recurving to the NE turn back after three days of NE movement. I have been warning for a while that the previous tracks that were showing no movement back north would be too far out to sea and it appears this is the case. It still does not appear a direct hit on Japan will occur. The GFS and Euro have come into pretty good agreement on a track just south of the country, with the GFS moving north some, and the Euro, which a couple times showed a direct hit, moving south some. As far as intensity, Prapiroon is forecast to intensify slightly to 100kts and then level off, with no change for a day or two, then steady weakening to 80kts by 5 days. Prapiroon has been interesting because unlike most West Pacific storms that have become typhoons this year, it didn't get there through rapid intensification. It has intensified at a rather climatological rate. I'd like some more microwave imagery to back this up, but I think the storm will soon enter into an eyewall replacement cycle, which should induce some short term weakening and long term strengthening. My forecast peak intensity of 110kts from a few days ago remains unchanged, and it should be reached in 24-36 hours. Beyond this time I think the official forecast shows too much weakening in later days. There remains a lot of time to watch this one and I'll provide more information as time goes on.


Figure 4: Typhoon Prapiroon. The small, ragged eye seems to indicate an impending EWRC.


Figure 5: Official JTWC track of Prapiroon.

91S Likely to Develop
A very interesting system continues to churn in the south Indian Ocean this evening, Invest 91S. Southern Indian Ocean cyclone season does not officially begin until November 15, but 91S may have other ideas. I'm lazy so I'll just paste in what the JTWC is saying about it:

(1) AN AREA OF CONVECTION HAS PERSISTED NEAR 5.8S 74.4E,
APPROXIMATELY 145 NM NORTHEAST OF DIEGO GARCIA. ANIMATED INFRARED
SATELLITE IMAGERY AND A 111300Z SSMIS SHOW A BROAD LOW LEVEL
CIRCULATION CENTER WITH FLARING DEEP CONVECTION ALONG THE SOUTHERN
AND WESTERN PERIPHERIES. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM
LIES FOUR DEGREES NORTH OF A RIDGE AXIS IN AN AREA OF MODERATE (15-
20 KT) VERTICAL WIND SHEAR AND GOOD POLEWARD OUTFLOW. SEA SURFACE
TEMPERATURES IN THE AREA ARE ESTIMATED TO BE FAVORABLE (>28 DEGREES
CELSIUS). MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO LOW.

I will add that both the GFS and Euro develop the disturbance, and it should continue to move SW for the duration of its life. This brings it in the general direction of northern Madagascar, but it is likely that if it does make it this far it will be in a much weakened state. Still, this will be quite the event if 91S does in fact develop over a month ahead of the scheduled start of the season.


Figure 6: Invest 91S, looking pretty good right now.

Latest Dvorak classifications of the systems I mentioned:

11/1800 UTC 6.1S 72.8E T1.0/1.0 91S -- Southwest Indian
11/1800 UTC 11.1N 104.2W T1.0/1.0 97E -- East Pacific
11/1745 UTC 26.0N 71.9W T3.0/3.0 16L -- Atlantic
11/1745 UTC 12.0N 58.3W TOO WEAK 98L -- Atlantic
11/1501 UTC 19.5N 128.5E T5.0/5.5 PRAPIROON -- West Pacific

Thank you for reading and have a great evening/night!

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1:45 AM GMT on November 09, 2012
MAweatherboy1 has created a new entry.
1. wxchaser97
11:06 PM GMT on October 11, 2012
Thanks MA!
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About MAweatherboy1

Average 18 year old weather nerd. Freshman at Plymouth State University, majoring in meteorology, with the goal of becoming a professional forecaster.

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