Above: In their 8 am Monday Tropical Weather Outlook, NHC gave 2-day and 5-day odds of tropical cyclone development in the Western Caribbean of 0% and 40%, respectively. |
An area of low pressure with the potential to develop into a tropical depression is expected to form in the Western Caribbean off the coast of Nicaragua by mid-week and move slowly northward, bringing heavy rains to Cuba by the weekend. The system may also bring heavy rains to South Florida and the Bahamas by the weekend, but due to the uncertain nature of the formation location and track of the storm, it is uncertain which region might be at most risk.
Satellite loops on Monday morning showed a large “gyre” of low pressure over Central America, with a modest amount of heavy thunderstorm activity that was disorganized. Conditions were favorable for development over the Caribbean waters off the coast of Nicaragua, with moderate wind shear of 5 – 20 knots, ocean temperatures a very warm 30°C (86°F), and high moisture at mid-levels of the atmosphere. All that is needed for a tropical depression to form is an atmospheric disturbance to get the air spinning.
8/ But what about #TCG? Uncertain b/c only ~50% of #CAG events have TCs & global models poorly handle which vort maxes become dominant. pic.twitter.com/AOWwWvE6iT
— Philippe Papin (@pppapin) October 22, 2017
Forecast
The 0Z and 6Z Monday runs of our top three models for predicting tropical cyclone genesis--the European, UKMET and GFS models--had two of them, the European and UKMET models, predict development in the Western Caribbean by Friday. Approximately 30% of the 70 members of the 0Z Monday GFS and European model ensemble forecasts also showed development. Model predictions of tropical cyclone formation from Central American Gyres (CAGs) are not very reliable, though, due to the uncertainty in where the center of spin associated with the Gyre will be (see the tweet above from Philippe Papin, showing three areas of spin, called vorticity maxes, or vort maxes, embedded within the Gyre). In their 8 am Monday Tropical Weather Outlook, NHC gave the future low 2-day and 5-day odds of development of 0% and 40%, respectively.
We'll have a post on Tuesday about the heat wave in Los Angeles. Monday's and Tuesday's highs in the city are expected to be 101°F, which would be the hottest temperature ever measured so late in the year. Will Tuesday be the hottest World Series game in history?
