WunderBlog Archive » Category 6™
Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.A quiet Monday in the tropics
The tropics are quiet again today. The low pressure system we've been watching the past week over the Bahamas moved inland over central Florida yesterday, and is not a threat to develop into a tropical storm today. However, if the center of this system can emerge over water, we might get some development. Some models are indicating the possibility of a center of circulation forming south of the Carolinas on Tuesday, then tracking northward. The Hurricane Center has a Hurricane Hunter aircraft ready to investigate anything that might pop up Tuesday. Regardless, this low pressure system will bring heavy rain and gusty winds to Florida and the Southeast U.S. over the next two days.
Figure 1. Preliminary model tracks for the low over Florida.
The well-defined area of low pressure far out in the Atlantic about 550 miles east-northeast of Bermuda we were watching over the weekend lost all its deep thunderstorm activity, and is also no longer worthy of discussion. The system that was forecast to develop north of Puerto Rico on Tuesday is now no longer being forecast to develop by the models. Wind shear is forecast to be quite high in this region over the coming week. In fact, wind shear is quite high over the entire Main Development Region (MDR) for hurricanes right now, as seen in the GFS model's wind shear forecast for 8 pm EDT tonight (00Z 27 June) plotted in Figure 2.
Figure 2. Forecast wind shear between 200 mb and 850 mb for 8pm EDT tonight. 850 mb is the typical pressure at about 5,000 feet in altitude, and 200 mb is the pressure at about 40,000 feet in altitude. The difference in wind speed between these two altitudes is a usually a good measure of the wind shear that affects tropical storm formation. Wind shear values less than 16 knots (8 m/s, the lightest two red colors) are typically needed for tropical storm formation.
New threat area east of the Windward Islands
A new area worth watching has cropped up near 7N 47W, about 1050 miles east-southeast of the southern Windward Islands. There is some heavy thunderstorm activity here and a 1012 mb low pressure area has developed. This low is moving west towards an area of higher wind shear, and is not expected to develop. Wind shear over most of the Atlantic is expected to remain seasonably high over the next week, making it difficult for tropical storm formation.
Figure 3. Preliminary model tracks for the low east of the Windward Islands.
I'll be back with up update on Tuesday.
Jeff Masters
Figure 1. Preliminary model tracks for the low over Florida.
The well-defined area of low pressure far out in the Atlantic about 550 miles east-northeast of Bermuda we were watching over the weekend lost all its deep thunderstorm activity, and is also no longer worthy of discussion. The system that was forecast to develop north of Puerto Rico on Tuesday is now no longer being forecast to develop by the models. Wind shear is forecast to be quite high in this region over the coming week. In fact, wind shear is quite high over the entire Main Development Region (MDR) for hurricanes right now, as seen in the GFS model's wind shear forecast for 8 pm EDT tonight (00Z 27 June) plotted in Figure 2.
Figure 2. Forecast wind shear between 200 mb and 850 mb for 8pm EDT tonight. 850 mb is the typical pressure at about 5,000 feet in altitude, and 200 mb is the pressure at about 40,000 feet in altitude. The difference in wind speed between these two altitudes is a usually a good measure of the wind shear that affects tropical storm formation. Wind shear values less than 16 knots (8 m/s, the lightest two red colors) are typically needed for tropical storm formation.
New threat area east of the Windward Islands
A new area worth watching has cropped up near 7N 47W, about 1050 miles east-southeast of the southern Windward Islands. There is some heavy thunderstorm activity here and a 1012 mb low pressure area has developed. This low is moving west towards an area of higher wind shear, and is not expected to develop. Wind shear over most of the Atlantic is expected to remain seasonably high over the next week, making it difficult for tropical storm formation.
Figure 3. Preliminary model tracks for the low east of the Windward Islands.
I'll be back with up update on Tuesday.
Jeff Masters
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.