Tropical Depression Two Discussion Number 1
Wiki-Hurricanes Forecast Center
5:00 AM AST Thu Jul 5 2018
The area of disturbed weather located about halfway between the Leeward Islands and Cabo Verde has acquired sufficient organization to be declared a tropical depression. A 2311Z ASCAT pass showed that, while the low-level circulation was not closed off, it was very close to doing so. More recently, enhanced shortwave imagery shows cyclonic low-level motion to the south and east of the suspected center, confirming that it is well defined. A series of microwave passes throughout the day shows that the system has a vigorous mid-level circulation, and conventional imagery depicts organized and persistent deep convection. Thus, advisories are being initiated on a tropical depression with winds of 30kt. It should be noted that the earlier ASCAT pass showed winds of tropical storm force; however, it is unknown how reliable these are.
The depression is moving swiftly west-northwest, steered by two mid-level ridges over the open Atlantic to its north. This motion should continue through the forecast period, steering the system near or through the northeastern Caribbean Islands by day 5, where enhanced precipitation will be possible. Significant impacts, however, are not expected.
Two is currently located in a marginally favorable environment. Anticyclonic flow is established aloft, keeping shear very low; the small size of the storm would make it even more susceptible to shear than average storms, and there is little evidence of that at the current time, confirming that upper-level winds nearby are indeed light. The storm is maintaining a healthy moisture pouch, with aid from the monsoon trough to its south and east. Water temperatures are around 26°C, slightly cooler than average for this time of the year. This environment should allow Two to persist or perhaps strengthen slightly over the next 36 hours. By Saturday, however, it should begin to interact with an anomalously strong TUTT near the Caribbean, and shear is expected to skyrocket to near 30kt. While waters will be warmer, mid-level relative humidity values are expected to fall to near 50 percent. Therefore, degeneration to a remnant low or trough is all but guaranteed.
FORECAST POSITIONS AND MAX WINDS
INIT 05/0900Z 30 KT 35 MPH
12H 05/1800Z 35 KT 40 MPH
24H 06/0600Z 35 KT 40 MPH
36H 06/1800Z 35 KT 40 MPH
48H 07/0600Z 30 KT 35 MPH