Dr. Jeff Masters' WunderBlog |
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| Posted by: Dr. Jeff Masters, 3:08 PM GMT on March 19, 2010 | +2 |



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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
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LOL!! :)
Lol, yeah I bet. The NHC is probably just like no way it's March, a month early, but the AEJ is further north than normal so it's possible. I don't know as much about analyzing tropical waves as weather456 does, and he's not here to help. From what I can tell it is definitely a weak surface trough, and it's in the right position south of the AEJ core, but it has a very weak signature, so I'm not sure what to make of it.
Oh you're right...didn't notice it was only the 6z discussion. Can't wait to see what the 12z says.
The NAM AND GFS differ on the amount of precipitation that will fall but they agree on surface temperatures generally slightly above freezing in the Fort Worth and Dallas areas during the event. The NAM shows weak lifting and lack of moisture in the dendritic growth zone to support anything more than trace amounts. The GFS shows the snow growth zone up around 7,000-8,000ft and the saturation in the mid levels and a dewpoint depression from 900mb to the surface. This should allow for evaporative cooling to the freezing wetbulb temperature. Up to a 1/2in of snow for Fort Worth and Dallas possible with areas further north can expect 1-3 inches especially those areas close the Texas/Oklahoma Border.
Nice. Hmm...
But check the water vapour image for the Atl.
It will get swallowed up whether its a wave or something else LOL.
Well yeah it's not going anywhere lol.
Me too. It's so low, ~5N. The ITCZ dives south as you go west. Not sure how much persistence we may see.
RGB loop..
Thanks Drak! We have had 1.05" of rain at the Dallas-Ft Worth Int'l AP here in N TX already today! And I saw a few light snow flurries flying around at about 12:10PM CDT!
Yeah. I'm actually really impressed with the AEJ right now. It's not even supposed to fully develop or be north of the equator during March, and yet it's up between 5N and 10N with stronger winds than normal right now. That's the only reason this could actually be a wave. I need to find 456's list of dates over the past 5 years when the first tropical wave formed. I believe they were all in late April and early May.
My vote: Surface Trough
Date of first tropical wave since 2004:
Note: after he made this list, the first 2009 tropical wave rolled off Africa on May 13th.
He decided to leave WU last December. He has new things to do in life. We all hope somehow he might come back but we can't count on it. He will be missed.
The thing that's confusing about it is a surface trough in the ITCZ actually IS a tropical wave, if it's during the summer. That's what a tropical wave is by definition, an inverted trough. If the NHC calls it just a trough then it would be because they don't think Africa is capable of producing a "real" tropical wave this early. That's because "real" tropical waves are created by the AEJ (African Easterly Jet). But that's why this could be so impressive because the AEJ actually is there, much further north and stronger than it should be this early in the year. Based on the trough's position, it actually could be a real tropical wave, if the signature is strong enough.
The thing is there really is no difference between a surface trough embedded in the ITCZ and a tropical wave. The only real difference is their methods of formation. You usually don't get a trough in the ITCZ if it's not a tropical wave or a monsoon trough.
What's The AEJ?
[Edit-Nevermind, I know now.]
African Easterly Jet, a belt of winds strongest at the 650mb level that travels across west Africa during the summer. Tropical waves form baroclinically and barotropically within and just south of this jet.
so surface trough or tropical wave
We'll see which one the NHC calls it at 18z.
EQUATOR NEAR 43W AND INTO NE BRAZIL NEAR 1S47W. CLUSTERS OF
SCATTERED MODERATE/STRONG CONVECTION ARE FROM THE EQUATOR TO 7N
E OF 07W. A SURFACE TROUGH IS EMBEDDED WITHIN THE AXIS FROM
2N-8N ALONG 24W. SCATTERED MODERATE CONVECTION IS FROM 2N-8N
BETWEEN 19W-28W. THE CONVECTION ASSOCIATED WITH THE SURFACE
TROUGH CONTINUES TO BE ENHANCED EAST OF AN UPPER LEVEL LOW
CENTERED OVER THE TROPICAL ATLC NEAR 6N34W.
Link
...ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N11W 5N23W 4N25W CROSSING THE
EQUATOR NEAR 43W AND INTO NE BRAZIL NEAR 1S47W. CLUSTERS OF
SCATTERED MODERATE/STRONG CONVECTION ARE FROM THE EQUATOR TO 7N
E OF 07W. A SURFACE TROUGH IS EMBEDDED WITHIN THE AXIS FROM
2N-8N ALONG 24W. SCATTERED MODERATE CONVECTION IS FROM 2N-8N
BETWEEN 19W-28W. THE CONVECTION ASSOCIATED WITH THE SURFACE
TROUGH CONTINUES TO BE ENHANCED EAST OF AN UPPER LEVEL LOW
CENTERED OVER THE TROPICAL ATLC NEAR 6N34W.
Vote? It's an election day?
K there we go. As I figured most of the convection is being enhanced by the large upper low to the west. It is an interesting feature to have this early in the year though. The AEJ is still quite impressive for March.
dev.gale centre
Boing!
High in the 50s tomorrow in SE LA...
Low 40s here :/
128 km Bowen Radar Loop
The Flying V? lol
a trough
not sure a backward tropical wave
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