Monthly Archives: October 2010

Dangerous Hurricane Tomas

Hurricane Tomas in the early morning hours was found to have winds of 100MPH and Tomas is now a category 2 hurricane. With data from the reconnaissance plane and satellite imagery, Tomas is better organized but it was noted that the vertical stack of the storm is tilted northeastward with height. The tilting is probably due to the Southwesterly shear that is beginning to impact Hurricane Tomas. The shear has been forecast and further intensification will stop for about 48- 72 hours. There is the possibility Tomas may lose some strength during that forecast period. After that period, the shear will relax and further strengthening is forecast. Intensity guidance in at least the LGEM model does have Tomas strengthening and possibly be a major hurricane of at least a category 3 storm.

Hurricane Tomas is currently located south of a mid-level trough that is over the southwestern Atlantic. As this trough continues to move eastward a mid level ridge will build just north of Tomas and this will turn Tomas on a westward track for the next 2 or 3 days. Later in the forecast period, that ridge breaks down as a very large deep layer trough moves into the eastern U.S. and also digs southward. This will slow the forward speed of Tomas and also allow Tomas to gain latitude. Model guidance at days 4 and 5 is poor as far as the timing and the the sharpness of the turn to the north but there is a consensus that there will be the northern turn as Tomas will be forced north by the trough.

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Hurricane Tomas

Tropical Storm Tomas has ben upgraded to Hurricane Tomas as of the 11am advisory from the NHC. Hurricane Tomas has had a very good presentation all morning. Hurricane Tomas is forecast to continue intensification and most models are forecasting that Tomas will be a major hurricane of at least category three.

The Mid-Layer trough that is taking Hurricane Shary rapidly to the NE is the same trough that is heading NE away from the Caribbean and the mid-level ridging north of Tomas has begun to build. Low to Mid level ridging is forecast by all the global models for at least the next 72-96 hours and building westward across Lesser and Greater Antilles. This will keep Tomas on a westward track for at least the next 2 days. A few days later, a broad mid-tropospheric trough that is currently located along the US west coast is forecast to move eastward into the Central US then it is forecast to dig southwestward into the Gulf of Mexico. This will erode the Western portion of the ridge and significantly weaken the steering currents in the western and central Caribbean Sea. This will force Tomas on a northward track. Exactly when the turn will happen is unclear. Some models want to wait then turn Tomas between Eastern Cuba and Haiti where other models want to turn Tomas earlier and have Tomas turn near Hispaniola.

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Tropical Storm Tomas

Invest 91L has been upgraded to Tropical Storm Tomas as of the 5PM advisory from the NHC. Earlier today, the reconnaissance plane had found that a closed surface circulation was forming and on the way to becoming a tropical storm. TS Tomas is expected to continue slow strengthening and may become a hurricane by Sunday. There is the possibility that TS Tomas may become a major hurricane later in the forecast period.

The models now are forecasting that TS Tomas will continue to head WNW for at least the next 72 hours. The broad trough over the US is now expected to pull out, and this will leave a ridge to build over Tomas and all the way to Florida. Later on, a second and much deeper trough will begin to dig southward into the Southeastern U.S. and this will cause the ridge and all the steering flow to weaken. This will cause Tomas to sharply decrease the forward speed in about 120 hours. It is too early to call whether Tomas will bypass the trough and continue heading WNW or whether the trough will begin to force TS Tomas to head NW then North or not.

NO MATTER where TS Tomas heads, all interests should keep advised of the location that Tomas is heading, especially if he becomes a major hurricane.

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Invest91L

Invest 91L located about 350 miles East – Southeast of the southern Windward Islands has been slowly getting better organized and is forecast to become a Tropical Depression or Tropical Storm in the next day or two. The overall environment and conditions are conducive for continuing development as the system heads W-WNW. A reconnaissance flight is scheduled later today (2pm). Most models are forecasting that Invest 91L will eventually turn N or NNE but the timing between the models makes things a little unclear. The latest models have it tracking between eastern Cuba and Hispaniola as a frontal system picks it up in a few days. Until we have the data from recon I would not begin to estimate what intensity will be.

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Tropical Storm Shary

Invest 92L was upgraded to Tropical Storm Shary as of the 11pm advisory last night. As of this morning, the center of TS Shary is exposed with convection to the west and south of the center. Shary has little chance to develop to hurricane status due to the forecast of cooler waters (SST’s) and in increasing vertical shear although the GFDL and HWRF want to forecast it to hurricane status. TS Shary is expected to become extratropical in 36 hours and it should dissipate as it is absorbed into a frontal boundary. Bermuda may be some effects from TS Shary in the next day or two.

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Invests 91L & 92L

Although the hurricane season is slowly winding down, there are three Invests in the Atlantic. 90L way out in the eastern Atlantic and is no threat.

Invest 91L is located 1200 miles E-SE of the Windward Islands. 91L is a vigorous wave and upper level winds will soon be conducive for possible slow development in the next few days. One possible problem for 91L that is very low in latitude and land interaction will hinder development as it heads W-WNW. One model (the Canadian) has it going right into South America where as the GFS model has it clipping the South American coastline.


Invest 92L is located about 650 miles East – Northeast of the Northern Leeward Islands. 92L has the potential in the next few days to become a tropical or sub tropical storm. There is no threat to the US mainland as the system will be forced to head N then NE due to the long wave trough (the Super Storm that is located along the Eastern Coast of the US).


I am posting an GOES13 Satellite image from earlier today showing the large “Super Storm”.

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Remnant Low Richard…

Tropical Depression Richard no longer has sufficient deep convection and has been downgraded to a Remnant Low. Although Richard is over water, dissipation if the system is forecast due to strong southwesterly shear along with dry air. The low is on a NNW track and is forecast to continue that track along the southwest periphery of a low-level subtropical anticyclone. Regeneration is highly unlikely.


Invest90L way out in the eastern Atlantic about 1150 miles NW of the Cape Verde Islands has continued to linger around for a while but it is headed NNW and away from any landmasses.

PGI66L which is SW of 90L is a an upper-level low system. Both 90L and PGI66L will be encountering some upper level winds which will inhibit further development, either tropical or sub-tropical.

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Zulu/UTC to Local Time

CONVERTING ZULU TIME TO LOCAL TIME

To make the conversion to your local time, see the chart below.

Find your local time in the first column. If you are on Eastern Daylight
Saving Time (EDT), you would use the second column to find your Zulu
Time/UTC.

For instance, if it’s 11 a.m. Eastern Daylight Saving Time
in Washington, D.C., it’s 1500 hours in Zulu time/UTC.

LOCAL
EDT
EST
CDT
CST
MDT
MST
PDT
PST
Midnight
0400
0500
0500
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1 a.m.
0500
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0600
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1000
3 a.m.
0700
0800
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1000
1000
1100
4 a.m.
0800
0900
0900
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1000
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5 a.m.
0900
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6 a.m.
1000
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7 a.m.
1100
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1500
8 a.m.
1200
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1600
9 a.m.
1300
1400
1400
1500
1500
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1600
1700
10 a.m.
1400
1500
1500
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11 a.m.
1500
1600
1600
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NOON
1600
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1 p.m.
1700
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2100
2 p.m.
1800
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2100
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3 p.m.
1900
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2100
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4 p.m.
2000
2100
2100
2200
2200
2300
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5 p.m.
2100
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0100
6 p.m.
2200
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0100
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7 p.m.
2300
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2400
0100
0100
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8 p.m.
2400
0100
0100
0200
0200
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9 p.m.
0100
0200
0200
0300
0300
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10 p.m.
0200
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0400
0500
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0600
11 p.m.
0300
0400
0400
0500
0500
0600
0600
0700
LOCAL
EDT
EST
CDT
CST
MDT
MST
PDT
PST
LEGEND:

EDT = Eastern Daylight Saving Time

EST = Eastern Standard Time

CDT = Central Daylight Saving Time

CST = Central Standard Time

MDT = Mountain Daylight Saving Time

MST = Mountain Standard Time

PDT = Pacific Daylight Saving Time

PST = Pacific Standard Time

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Tropical Storm Richard

Invest 99L has been upgraded to Tropical Depression Nineteen as of the 11PM advisory last night from the NHC. Strong upper level winds, shear, and dry air were inhibiting development and at times the “center” was reforming in different areas. After most of the day yesterday trying to develop, the system had headed east then southeast. Shear and the upper level winds were decreasing and the Recon plane found a closed circulation with enough winds to be classified as a tropical depression. The D-Max along with shear decrease at this time looks like it is on the edge of becoming Tropical Storm Richard if not already so. The last reconnaissance plane data before writing this blog found an SFMR (Stepped Frequency Microwave Radiometer – measures wave frequencies from the surface for wind direction/speed of systems) reading of 44kts, uncontaminated. If the data is correct then Tropical Depression Nineteen will be upgraded to Tropical Storm Richard, probably at the 11am advisory from the NHC.

This soon to be designated Tropical Storm now has a better chance of developing into a hurricane and many models are agreeing to that. A few days ago, I didn’t think the storm would possibly affect Florida because of all the different variables, but has been the case with so many storms, Mother Nature has her way and this may affect Florida. The GFDL and HWRF have been forecasting the way this storm has been developing and if this trend continues then everyone in the the Yucatan, Western Cuba and possibly Florida should keep tabs on this storm. Although, at least for the moment, I think the storm intensity might be a little too high as the two models are a little too aggressive so I would tend to dampen it to a more reasonable value. The GFS model wants to have landfall in the Yucatan, then have the system back over warm waters in the Southern GOM and possibly head to Texas or the Gulf States, Florida.

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Invest 99L – A Possible Florida Threat??

Invest 99L which has been lingering around the Southwestern Caribbean is finally beginning to move away from the coasts of Nicaragua & Honduras. With landfall interaction, it was impossible for 99L to even try to develop. Now that it has been been heading N or NNW it has a much better chance of developing. This is the time of the year where the models have problems and this may be the case with 99L. Many of the models at this time are not seeing any type development but the GFDL and HWRF does favor development. Whether 99L will be a Florida threat or not is a forecast that is so very difficult to answer, at least for the next few days. Hopefully, with a few hours or so we may have a better idea of what might happen as the reconnaissance flight is on it’s way. Just looking at the satellite presentation, it does look like there is circulation at the mid and upper levels but not yet at the surface. I am sure this is what recon will find.

Below are the two models GFDL & HWRF which develop 99L into a hurricane. Only if shear abates, the high pressure system that will build after the trough has gone through and the high heads east and 99L lingers into the Southern Gulf of Mexico, then the chances for 99L to head to Florida as a tropical cyclone may increase but I doubt this will happen as there a just too many variables that have to work in unison.

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