Tropical weather analysis - October 2, 2012

By: KoritheMan , 4:29 AM GMT on October 03, 2012

Share this Blog
4
+

Nadine

The eternal Nadine continues to move across the eastern Atlantic toward the Azores (again). As of the latest NHC advisory, the following information was available on the cyclone:

Wind: 50 mph, with higher gusts
Location: 34.4°N 35.7°W
Movement: E at 9 mph
Pressure: 996 mb

There is little I can say about a storm that has lasted for 82 advisories. The cyclone appears to be gradually losing organization. Strong northwesterly shear associated with a mid- to upper-level trough to the northwest has exposed the center to the western edge of the convection, although the convection still shows some banding.



Figure 1. Latest infrared satellite image of Tropical Storm Nadine. Image credit: RAMMB Colorado State University (CSU).

Sea surface temperature analyses indicate that Nadine is over SSTs of about 22 to 23C. While this is well below the threshold generally needed for tropical storm formation, AMSU temperature data suggests that the upper troposphere remains colder than normal, which has likely assisted the cyclone in lasting longer than would normally be expected for a tropical cyclone over cold water. Indeed, this is often the case with many high-latitude storms that traverse the subtropics. Unfortunately, these events are difficult to predict, which is why we usually don't incorporate them into our intensity forecasts.

In about 48 hours, a significant increase in southwesterly shear is forecast as a very strong baroclinic zone approaches Nadine. The tropical storm is forecast to respond by quickly weakening -- no matter how baroclinic an environment is, a system possessing any semblance of a warm core cannot survive in such ambience. Concurrent with its expected northeastward movement, water temperatures will cool even further, especially beyond 24 hours, when they will fall into the sub-20C range. Consequently, Nadine is forecast to lose tropical characteristics in about 48 hours. The global models suggest the cyclone will become absorbed just after 72 hours, so a day four forecast point will not be given.

Water vapor imagery shows that a deep-layer low pressure system is amplifying to the west of the tropical cyclone. Large-scale southwesterly flow is quickly approaching Nadine, and the storm is expected to soon turn northeastward as a result. Significant acceleration is forecast throughout the next three days. The model consensus remains tightly clustered as the synoptic pattern is straightforward. There is some suggestion that Nadine may move westward around the northern side of the north Atlantic low subsequent to being absorbed by it, but it would take a miracle for it to regenerate at that point.

I am in good agreement with the National Hurricane Center forecast track.

5-day intensity forecast

INITIAL 10/03 0300Z 45 KT 50 MPH
12 hour 10/03 1200Z 45 KT 50 MPH
24 hour 10/04 0000Z 45 KT 50 MPH...APPROACHING THE AZORES
36 hour 10/04 1200Z 45 KT 50 MPH
48 hour 10/05 0000Z 40 KT 45 MPH...POST-TROPICAL/EXTRATROPICAL
72 hour 10/06 0000Z 35 KT 40 MPH...POST-TROPICAL/EXTRATROPICAL
96 hour 10/07 0000Z...ABSORBED BY NORTH ATLANTIC LOW

5-day track forecast



Figure 2. My 5-day forecast track for Nadine.



Invest 96L

A vigorous tropical wave in the eastern Atlantic about 950 miles west of the Cape Verde Islands continues to show signs of organization. UW-CIMSS analysis suggests that an upper-level anticyclone is building over the disturbance, although earlier microwave data indicated that the circulation is not real well-defined. While the circulation seems to have become a little better defined since that time, it appears to be located along the far southern edge of the convection. Even that is hard to make out with nighttime imagery and a center that was not well-defined in the aforementioned microwave images.

Environmental conditions appear favorable for additional organization, and this system could become a tropical depression over the next day or two as it moves northwestward at 10 to 15 mph. Model guidance suggests this system will recurve well east of the Lesser Antilles due to the large-amplitude trough recurving Nadine. A weaker system would probably head more west and possibly threaten the northern Leeward Islands in the long-range. This appears unlikely given the current organization of the system and the favorable upper-level winds ahead of it.

Probability of development in 48 hours: 80%

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 3 - 1

Page: 1 — Blog Index

3. WunderAlertBot (Admin)
4:27 AM GMT on October 04, 2012
KoritheMan has created a new entry.
2. KoritheMan
6:25 AM GMT on October 03, 2012
Quoting LostTomorrows:
I will be sad to say goodbye to Nadine. She's like that annoying bratty sister that you never thought you'd ever miss until she gets kidnapped all of a sudden.

And I'm calling for a TD before noon tomorrow... could be 5 am, could be 11, but I doubt it'd take longer to be classified. Whereas Nadine will finally sing her swan song, Oscar will be going Wilde. Kinda poetic, I guess.


Liking the sister analogy. ;)
Member Since: March 7, 2007 Posts: 602 Comments: 21302
1. LostTomorrows
6:11 AM GMT on October 03, 2012
I will be sad to say goodbye to Nadine. She's like that annoying bratty sister that you never thought you'd ever miss until she gets kidnapped all of a sudden.

And I'm calling for a TD before noon tomorrow... could be 5 am, could be 11, but I doubt it'd take longer to be classified. Whereas Nadine will finally sing her swan song, Oscar will be going Wilde. Kinda poetic, I guess.
Member Since: August 26, 2008 Posts: 0 Comments: 617

Viewing: 3 - 1

Page: 1 — Blog Index

Top of Page

About KoritheMan

I'm just a 23 year old with an ardent passion for weather. I first became aware of this interest after Tropical Storm Isidore struck my area in 2002.

KoritheMan's Recent Photos

Porygon
Hurricane Keith
Another boring selfie.
Shugo Kunisaki