| dem05 |
| (User) |
| Sat Aug 18 2007 11:12 AM |
| Attachment |
Dean and the Upper Level Pattern
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I’ve attached an image I created that depicts the upper level features over the CONUS and Atlantic Basin. You may want to make a copy to follow along in the discussion. I hope it helps in depicting some of what I am seeing.
I’d also like to repost the Water Vapor Links:
Pacific NW Water Vapor Loop: http://www.goes.noaa.gov/GSSLOOPS/wcwv.html
Atlantic Wide Water Vapor: http://www.ssd.noaa.gov/goes/east/tatl/loop-wv.html
NW Atlantic Water Vapor: http://www.ssd.noaa.gov/goes/east/nwatl/loop-wv.html
CONUS Water Vapor: http://www.goes.noaa.gov/GSSLOOPS/ecwv.html
Well, I have a bag full of wrenches, so I may as well start throwing. Before I do however, I do want to caution that I will not be delving into the models or basing my statements on much of what the models have to say. Traditionally, this is a dangerous game, but with indication that the models are having a tough time in initializing storm intensity, the intensity of the upper level features, and problems with the models racing Dean off probably a bit too fast, I’ve decided not to go much farther in my discussion of them than this. With that said, the models very well may have the correct solution albeit they are not performing as well as one would hope.
The breakdown:
The Florida Upper Level Low is on the move again. From my best estimate, the center is probably right about above my head here in SW FL as I type. It does look like it is now trying to tuck south of the High Pressure Ridge. At some point, I will imagine that the Upper Low will have to either stall or phase out. At this point, it shows no evidence of phasing out, but that may happen in a couple days. Earlier, someone asked about Dean’s forward speed slowdown and how the interaction will affect track. If the Upper Level low had been stationary right now, we would likely expect that Dean would be turning North at some point. However, The Upper Level Low is also moving westward, so I would expect it’s overall influences to resulting a general WNW motion for the next 2-3 days. Dean is probably close enough to feel some of these effects now, but it is also far enough away that I would expect to see subtle fluctuations in forward speed and direction. In other words, Dean slows down a bit, the ULL moves a bit further away, the ridge builds backing a bit and Dean will move slightly faster and a little more westerly…Then Dean will catch up again, slow down and move a bit more WNWerly. In general though, I would not dismiss the Idea that Dean may get closer to Haiti than anticipated. Later on down the road, if the Upper Level low does not phase out and it stalls between 90-95W…I would say that chances for problems in the Eastern Gulf would really increase…Otherwise, the further west it can move before stalling or dissipating will result in problems points west.
Side note/disclaimer: The yellow arrows do not show a forecasted track. They are just there to show the upper air flow ahead of Dean.
Looking at the mid latitude weather systems and the jet stream, there are some other considerations to make. The jet stream over the CONUSis not zonal like it was a few days ago. (The jet stream is identified in the pink, the movement of the jet stream is outlined with Green Arrows). The trough over the Northeast US is moving out and being replaced by a ridge. The ridge is highlighted in Blue and this is the feature that the Florida ULL will sweep under. With that said, the ridge IS moving east, and may continue to do so through this evolution. There is a pretty darn good trough entering the Pacific. This trough is probably starting to move the US weather patterns along. At this time, I know the $64,000 question would be…Will that trough get into the Gulf area. Unfortunately, I don’t have an answer for that or if it would have a direct affect on Dean…But it is something to watch, and I have included a link to the Pacific NW Water Vapor Loop. With that said, it is not impossible to assume that the Florida ULL may stall in a couple days as the High Pressure ridge moves east and the Upper Level Low moves around to the SW Side of the ridge. For an additional quirk that may be another wildcard factor…It does appear that the remnants of Erin may also be evolving into a weak upper level low feature. I really can’t say that this would have any ramifications on the overall upper level pattern, but over time, it will be interesting to see if anything unfolds with that.
So that’s basically the way I see it right now…Unfortunately there are more questions than answers, but it is still to early to Pinpoint specific threats and/or dismiss any Gulf Coast possibilities at this point. Keep on tracking…