WunderBlog Archive » Category 6™

Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.

Tropical wave has potential to develop into tropical depression

By: Dr. Jeff Masters, 2:09 PM GMT on August 07, 2006

A tropical wave over the mid-Atlantic near 12N 42W, about 1300 miles east of Barbados, has the potential to develop into a tropical depression. However, the long-term survival of this system is questionable. The wave has a well defined surface circulation, and is currently under about 10-15 knots of wind shear, due to upper level winds from the east. As the wave moves westward over the next 36 hours, it should encounter an area of lower wind shear where these upper level winds will relax, and I believe a tropical depression will probably develop by Tuesday night. However, as the wave continues westward at 15-20 mph, it is forecast to encounter strong upper-level westerly winds associated with the counter-clockwise flow of air around an upper-level low pressure system northeast of Puerto Rico (Figure 1). This strong wind shear should weaken or destroy the wave. This is shown well by the GFDL model, which intensifies the wave into a weak tropical storm by Wednesday, then dissipates it later in the week. None of the other computer models develop the wave at all.


Figure 1. Water Vapor satellite image from 8:45am EDT August 7. Note the substantial dry air (brown colors) to the northwest of the tropical wave we're watching, and the upper level low to the northwest of the wave that is expected to bring strong westerly wind shear later this week.

Intense thunderstorm activity associated with the wave is mostly on the west side of the circulation, due to the strong upper-level winds from the east pushing all the convection over to that side. There is a substantial amount of dry air to the northwest of the wave, as seen in the water vapor image from this morning (Figure 1.) This dry air has resulted in a decrease in the intensity and areal coverage of the wave's thunderstorm activity this morning. If we do get the expected decrease in wind shear later today and tomorrow, this should allow the thunderstorm activity to build back in over the circulation center.


Figure 2. Preliminary model tracks for the mid-Atlantic tropical wave.

For today, it does not appear that this tropical wave is going to be a major threat. I'll be back with an update on Tuesday. Elsewhere in the tropical Atlantic, there are no threat areas to talk about.

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.

Reader Comments

00
ABNT20 KNHC 081502
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1130 AM EDT TUE AUG 8 2006

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A SMALL AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE IS
CENTERED ABOUT 825 MILES EAST OF THE WINDWARD ISLANDS...AND IS
MOVING WESTWARD 15 TO 20 MPH. ALTHOUGH THUNDERSTORM ACTIVITY IS
MINIMAL AND UPPER-LEVEL WINDS ARE ONLY MARGINALLY CONDUCIVE FOR
DEVELOPMENT...THIS SYSTEM STILL HAS SOME POTENTIAL TO BECOME A
TROPICAL DEPRESSION DURING THE NEXT DAY OR SO.

LOL, ya beat me
With the peak of the Atlantic hurricane season upon us, experts from NOAA are reiterating their prediction for an above-normal number of storms. NOAA scientists warn this year's relatively quiet start is not an indication of what the remainder of the season has in store. "This year's three named storms may pale in comparison to the record nine storms that formed through early August 2005, but conditions will be favorable for above-normal activity for the rest of this seasonso we are not off the hook by any means," said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. For the entire 2006 season, which ends November 30, NOAA is projecting a total of 12 to 15 named storms of which seven to nine will intensify to hurricanes, including three or four becoming major hurricanesrated at Category 3 or higher.
Here is the text of the outlook...

CLICK HERE








been blob watchin this mornning.... certainly not tropical... but interesting none the less.... perhaps due to its close proximity.... :)
Hey Jp, I new blog is up
turtle when are we officially starting the cape verdes season this year...i cant see anything developing this month and we may not see our first hurricane until labor day ...now that is kind of strange..the african dust which i said all along will stop any thing that comes off the coast from developing...gents we are in for one boaring season until mid september and october seems to be a very active month..so you can throw the cape verdes season in the toilet like everyones predictions on here this year...weatherguy03 needs to study a little more and lighten up with his b/s he is giving you..he never commits to anything he wont give you a srraight answer when you ask him a question...like i said people this hurricane season is in the books and by the way IT IS WRITTEN IN STONE!!!!!!!!!!!!!!!!!!!StormTop
hey guys accuwweather dropped 91L HA wouldnt it be funy if it devoloped!!LOL:)