[Martyn Wells]

Can I sugest we use this thread to disucss tropical model output, and to speculate on potential future cyclones?  This way we can keep the *potential* discussion away from the main storm threads.

To kick off with, the GFS suggests that the convective mass inland over western Africa at the moment will emerge from the coast as the next tropical wave following Bertha and quickly form into the next TS of the 2008 season.  Due to a strengthening ridge, forward speed of this feature is not exactly slow, and probably as a result, development is correspondingly slow.  This has been a feature of the lat 4 GFS runs; it shoudl be borne in mind that GFS had Bertha on 20 consecutive runs before she actually formed.

And you are all defintely right, I should get out more :)

Finally, as is with other areas of the UKWeatherworld forum, but more so the tropical forum, the contents of these threads are for discussional purposes only, and should not be used by anybody as a forecast of future events.  For detailed and accurate forecasts, consult with your local met office, who will provide you with forecasts specific to your area.

[EllyTech]

Is Bertha strengthening? ...

[EllyTech]

Thanks Martin.

I see the new 'low'. Will follow this one - to watch how the surrounding conditions affect it. To me, it seems that when flanked by high pressure zones, this affects its deepening somehow. Is that primarily due to warm water and not necessarily related to pressure or, have I got it all completely wrong - ?

[EllyTech]

That is a brand new thing I've learned today, Martin Thanks!

This must all become intuitive - when you know the factors to look out for. Sorry to bother you with another question but I need to understand (probably learn by heart) which altitude pertains to which pressure (eg 850 mb theta-E): What in the GFS runs am I to look at, to find sea temperatures?

[EllyTech]

Doh! Why did I not see that link after all the time I have been using that site?! Thanks again Martin - now I have a lot to go with.

[EllyTech]

Often wondered why they weaken shortly after landfall - totally explains it.

So, when trying to forecast Tropical storm development (or, indeed, hurricane), we look for a sudden anomaly 'low' moving, not stationary; warm seas then all the other types of factors that are associated with vortex creation - ? Though, as you say, there are many many factors involved. Not as 'simple' (I use that word only to place perspective on forecasting complexity) as spotting tornado potential, is it?

Praise should be given to GFS if it is able to spot potential before other models - checked most of the others and they do not show the new 'feature'.

[EllyTech]

Wiki - Fantastic read, Martin...very detailed. Still have some to read (especially some of the links) but it is answering a lot of the questions I have. As is always with me, I need to get to a point of 'visualization' of the mechanisms to be sure it has been digested and understood. :-)

[EllyTech]

GFS 06Z shows Bertha being absorbed into a low pressure system around Iceland then a development from that seems to generate a new ...'thing', to the West of the British Isles -

http://moe.met.fsu.e...sure&hour=168hr

[Halo]

Impressive wave with a large circulation. Do any of the models develop this? 

A VIGOROUS AND WELL-DEFINED TROPICAL WAVE IS LOCATED OVER WESTERN
AFRICA A COUPLE HUNDRED MILES EAST OF DAKAR SENEGAL.  THIS SYSTEM
HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE VERY QUICKLY AFTER
IT EMERGES INTO THE EASTERN ATLANTIC WITHIN THE NEXT DAY OR TWO.

[admin]

From http://www.nhc.noaa.gov/gtwo_atl.shtml

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM  
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT WED JUL 30 2008

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

1. A WELL-DEFINED AREA OF LOW PRESSURE IS LOCATED ABOUT MIDWAY BETWEEN
THE CAPE VERDE ISLANDS AND WESTERN AFRICA AND IS MOVING TO THE
NORTHWEST AT 10 TO 15 MPH.  THIS SYSTEM HAS THE POTENTIAL TO BECOME
A TROPICAL DEPRESSION TODAY BEFORE MOVING OVER COOLER WATERS
TOMORROW.   INTERESTS IN THE CAPE VERDE ISLANDS SHOULD MONITOR THE
PROGRESS OF THIS SYSTEM.  REGARDLESS OF DEVELOPMENT...HEAVY RAIN
AND GUSTY WINDS ARE POSSIBLE OVER THE CAPE VERDE ISLANDS LATER
TODAY AND TOMORROW.  

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$ 
FORECASTER BLAKE

 

[Cindy]

I was just checking this out on the NHC site Dave. They had it as a 'low' chance for development yesterday.