Ups and Downs with 94L

Just an overview for tonight, but an important one nonetheless. Our invest 94L has gotten organized enough that it has both moderate convection and organization. Obvious banding and a mid-level center appeared on satellite today. The comma shape commonly seen with organizing systems also appeared today with excellent outflow rotating clockwise away from the system. This is the upper level anticyclone that helps cyclones breathe.

That was the good news, but the bad news is that the low-level center continues to move well ahead of the well-defined mid-level center. Bad stacking of cyclones is like putting a large pile of pancakes on top of each other except each one is slightly off of the one above it. Eventually the stack of pancakes is gonna fall over. In this case, 94L is leaning to the right. Mild shear often causes this as it has in 94L, and that shear can kill low-level centers. When this happens that bottom pancake disappears and the pancake above it spins down to replace it. A new low-level center may rebuild over night.

The mid-level center continues to impress me tonight. Generally with systems in the early stages such as this one, they often impulse during each 24-hour day. As explained in the Meteorology Mumbo, this is called diurnal variability. 94L has surprises in store however. Storms tend to weaken right around sunset and in the hours after, which 94L did at first. Since around 10pm ET, storms have been firing over the mid-level center. This is important because it may signal that 94L has gotten past the diurnal stages of growth, and may be able to convect at all hours of the day. We’ll see tomorrow if it can sustain itself without losing all of its thunderstorms.

Also of note is that there is a chance that the Hurricane Hunters may fly into 94L during the afternoon Monday. I believe this is the best chance of them flying this week, as they have turned down all opportunities thus far.

It is also important to note that time is running out on 94L. As 94L continues to move every so slowly toward the Yucatan, the conditions (primarily shear) will begin to deteriorate for the system. I expect to see exactly what June systems generally look like after 94L begins hitting moderate shear: ragged. We will talk about this in the coming days as we get closer. Until then we will watch. If the hurricane hunters make a flight later today (Monday), I will be tweeting their findings and will make a post after the flight is over. Good night!


Posted on Monday, June 6th, 2011, in Tropical Weather and tagged , , . Bookmark the permalink. Leave a comment.

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