Weather

Tropical storm Don headed for the Caribbean - "Talking the Tropics With Mike" - July 18th

July 18, 2017 — Tropical storm Don is moving swiftly westward & will enter the SE Caribbean by early Wed.  The storm continues to organize but has an intense battle ahead with an abundance of dry air as well as increasing wind shear - especially be late Wed. through the end of the week.  So "Don" is expected to weaken & eventually degnerate into an open tropical wave but not before hitting the Southern Windward Islands late Tue. through early Wed. with strong winds & very heavy rain.

An interesting sidenote from Dr. Phil Klotzbach, CSU: "Don is the 2nd deep tropical system of the season (Bret was the first) - to develop south of 23.5 degrees N & east of 27 degrees W.  This is only the 12 hurricane season during which two or more of these occurrences have happened before Aug. 1 & each year most of those seasons have been active over the Atlantic Basin".

The Bermuda high over the Atlantic remains expansive so "Don" & a strong tropical wave to its east are likely to move on a pretty straight west heading into the Caribbean.

Spaghetti plots for "Don":

Spaghetti plots for the wave - '96L' - that trails "Don".  More of a northwest movement is expected into a pretty hostile environment of very dry & stable air.  More models will be added to the plot below once the system is detected by more of the models....

Imagery below courtesy CIMMS continues to show a well established "blob" of African Saharan dust (orange & red) continues over the Central & E. Atlantic - an indication of dry air.  In fact, the most recent surge west of dry air is moving in on the Caribbean & some of this dust will likely be over parts of Florida by late week.  "Don" has is just on the edge of this dry & stable air.

Water vapor imagery shows that "Don" will also be moving into some dry mid & upper level air over the Caribbean....

Surface analysis centered on the tropical Atlantic shows the strong Bermuda high anchored over the Central & Eastern Atlantic which is helping to guide "Don" just about due west...

Surface analysis of the Gulf:

Caribbean:

0

Wind shear analysis - pretty harsh across the Central Atlantic & much of the Caribbean (typical for July) as "Don" exits a relative lull in shear moving into a high shear "zone"....

1

Tropical waves are moving off the coast of Africa. The area is largely being held in check by the Saharan dust plume alluded to earlier.... & the "popcorn" type cloud cover from 10 to 30 degrees N (also visible in the 6th image from the top) is indicative of stable air.

In the E. Pacific.... once powerful "Fernanda" is over open water & will bend more west with a weakening trend well before reaching Hawaii.  A couple areas of disturbed weather follow with "Greg" farthest to the right (east) & closer to Mexico... could have "Hilary" also develop between the two systems.

"Fernanda":

"Greg":

"Greg":

"Fernanda":