Tropical Tidbits from the Tundra

TD #16 gaining strength

By: Levi32, 2:51 PM GMT on October 28, 2007

TD 16 formed last night south of the Dominican Republic, and has been organizing nicely during the night. Very deep convection has been persisting for almost 24 hours over and NE of the COC. This convection is becoming more centered over the COC as time goes on and shear slackens. Shear is now below 15 knots and should allow for more organization today. Based on satellite appearance this morning I have no doubt that the NHC will upgrade to a TS at the 11am advisory. The spin is clearly centered under the CDO on visible loop, and outflow is improving to the north, east, and south. The western semicircle needs some work, but it should fill out with time as TD 16 organizes today.

Models are still very divided on the future track. The GFS, GFDL, UKMET, and the HWRF want to take this north over Haiti and out into the Bahamas. The NOGAPS and BAMS take this a little more west between Jamaica and Cuba and stall it over the western Caribbean, which would favor much more intensification. I am tending to agree with Dr. Masters that the NOGAPS is more reasonable than the rest of the models in this situation. Unless the frictional effects of Haiti and Cuba reek havoc with TD 16, I don't see it being pulled that far north that fast. The trough forecasted to provide the weakness for TD 16 to go through will be moving out in a couple days, leaving the door for a hit on the US still open. The good news is that TD 16 will likely make a prolonged journey over Cuba at some time in its life, making the threat of a serious hurricane landfall on the US minimal. If the NOGAPS ends up being right and the storm spends time over the western Caribbean then we could be looking at a possibly major hurricane hanging around sometime next week. Currently I agree with the NHC forecast, which takes the average of all these scenarios, as the uncertainty is very high with this system.

We shall see what happens!
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SSD Dvorak Intensity Estimates

CIMSS Dvorak Intensity Estimates

SSD tropical formation probability and other maps

CIMSS satellite derived winds and analysis

Atlantic Models

Navy Tropical Cyclone Page

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CIMSS Saharan Air Layer Analysis

METEOSAT Satellite Imagery (Updated every hour)

North Atlantic WV Loop (The Big Picture)

Updated: 2:56 PM GMT on October 28, 2007

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"Calm" winter weather

By: Levi32, 5:16 PM GMT on October 15, 2007

After a whole inch of snow from our last storm, the temperatures warmed enough to melt most of it. Temperatures have dipped below freezing again with clear skies and light air flow. Several fronts draped across the north Pacific will be trying to edge north in the next few days, bringing scattered snow showers to most areas. Classic "calm" winter weather consisting of partly sunny skies with the scattered snow shower and biting cold. The storm tracks will continue to be into the gulf, which I suspect will be the dominant pattern through much of the winter with La Nina in place. Temperatures are slowly coming down and a permanent snow cover is only weeks away.

We shall see what happens!



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Winter Arrives in Alaska

By: Levi32, 6:06 PM GMT on October 12, 2007

Quick on the tropics:

TD #15 has formed and will move out to sea without being named in my opinion. Invest 97L has formed in a very interesting spot just off the NW African coast, and probably won't develop very much. The Caribbean and GOM need to be watched during the next couple weeks as waves continue to move through the area. Keep in mind this is also where the focus of activity shifts to late in the season.

For my first Alaska weather post in a long time, I am happy to report that it is snowing! :) Abnormally cold temperatures have been pouring in from the pole causing some early frost/freezes across the southern areas. Yesterday a weakening parent low over the Bering Sea brought a sluggish front over southwestern Alaska bringing rain/snow mix at higher elevations and rain at the surface. Today a triple-point low has formed just east of Kodiak and will strengthen today and tonight, moving slowly NNE. This new low is pulling more arctic air down into its back side, and snow showers have been spreading west this morning from the gulf as temperatures dip below freezing. The position and intensity of this new low will determine if anyone gets any accumulative snow out of this. The GFS is showing a classic deepening to 978mb and a curve up into Prince William Sound, which is always the best setup for snow in the southcentral area. The NAM is more conservative on deepening the low and tends to sluff it off to the east, sparing us the snow. I'm leaning more towards the GFS solution this morning with a 130kt jet-streak helping to deepen the triple-point low. This jet will sit over the SE panhandle for the next 3 days feeding warm moist air into the low, which, combined with arctic air on the back side, could result in some decent snows in some areas.

Winter is here early compared to the last 5 years, probably due to the La Nina pattern currently in place. If La Nina holds we could be looking at a more normal winter by Alaskan standards, which means colder and snowier :)

We shall see what happens!



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Updated: 6:07 PM GMT on October 12, 2007

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Fairly quiet tropics

By: Levi32, 4:21 PM GMT on October 08, 2007

Yes I know....I'm very inconsistent at writing blogs...and I admit it lol.

Invest 94L is not noticeably more organized this morning, and I don't believe we will see anything form fast out of this system. 94L is a broad area of low pressure just east of the Yucatan Peninsula, and will be drifting around for a couple days. The environment is fair for intensification, but like a lot of our latest disturbances this one could just fizzle without developing.

I believe this decline in named storms over the last week and a half is directly related to the MJO pulse currently over the western Atlantic basin. A pulse of downward atmospheric motion moved in a week ago and has refused to go away. Conditions are now close to neutral, but until we get the positive pulse back disturbances will have a hard time sustaining heavy and consolidated convection. We should be out of this downward pulse by the end of this week, and some late-season waves might finally have a chance to develop in the Caribbean as is typical for this time of year. The concern for a late-season major hurricane forming in the western Caribbean and recurving northeast over Florida is still valid. SSTs are very warm, and the NW Caribbean/SE GOM is still relatively untouched this season.

My take on 94L is that it needs to be watched, but chances are it will either fizzle or move over the Yucatan before it has a chance to develop into anything menacing. However, this is the time of year to start watching the Caribbean, just like in the spring-time. The upper-air patterns are very similar with upper troughs starting to dig into the GOM to fish out whatever tropical mischief might be waiting.

We shall see what happens!


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SSD Dvorak Intensity Estimates

CIMSS Dvorak Intensity Estimates

SSD tropical formation probability and other maps

CIMSS satellite derived winds and analysis

Atlantic Models

Navy Tropical Cyclone Page

National Hurricane Center


NASA High-resolution GOES Satellite Imagery


CIMSS Saharan Air Layer Analysis

METEOSAT Satellite Imagery (Updated every hour)

North Atlantic WV Loop (The Big Picture)

Updated: 4:24 PM GMT on October 08, 2007

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About Levi32

Levi Cowan has been tracking tropical systems since 2002, and is currently working on his bachelor's degree in physics at UAF.

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