Masters student in tropical meteorology at FSU. Raised in Alaskan blizzards, but drawn toward tropical cyclones by their superior PGF.
By: Levi32 , 5:16 PM GMT on June 22, 2009
Andres Update 5:30pm eastern time:
High-resolution visible loop of Andres and BOC system
Andres doesn't seem to have changed much since this morning. Estimated overall forward motion is towards the NW at 4kts, but motion has been erratic since this morning due to weak steering currents between the upper high over the southern US and the upper trough over California. Andres has been trying to form an eye structure throughout the afternoon with little success, but the system exhibits a nice CDO with tight curved convective banding. Upper-level outflow remains well-established in the SW quadrant, and also in the SE quadrant with outflow being enhanced by the upper trough in the western Caribbean. Outflow is severely limited to the north due to Andres' proximity to an upper-level low over central Mexico. Andres is not over an area of particularly high ocean heat content and SSTs drop off rapidly west of 105W on Andres' current trajectory.
Due to these factors and Andres' forecasted proximity to the Mexican coast over the next 2 days, I don't expect more than a minimal Cat 1 hurricane at peak intensity. Hurricane warnings have been posted for portions of the Mexican coastline. A hurricane warning means hurricane conditions are expected within 24 hours.
Tropical Tidbit from 1:30pm EDT Monday, June 22, 2009:
Here's my 3rd video:
Turn up the volume, and click HD if the quality is too low:
Tropical Storm Andres:
The east Pacific finally has its first named storm of the season. Andres is sitting just SW of Guerrero, Mexico, and if he gets any closer to the coast it could limit his intensification. This would be good for Mexico as Andres is in an environment favorable for intensification into a Cat 1 hurricane. Andres is embedded in a weak steering flow on the SW side of the upper high sitting over Louisiana. This flow will take Andres slowly towards the NW and likely very close to the Mexican coast of Colima and Jalisco through Wednesday. This slow motion will mean lots of rainfall along the coastline, with the GFS forecasting a total of 6-10 inches as a general rule for these areas. The NHC forecasts Andres to become a minimal hurricane just off the coast of Jalisco in 36 hours before land interaction weakens it back to a tropical storm. I have doubts about this forecast if the track is as close to land as the NHC is forecasting. Regardless, rain will be the primary issue with this system, and for mountainous countries like Mexico slow-moving tropical cyclones near the coast can be nightmares.
It's still pretty quiet in the Atlantic which is typical for June. Andres' competing circulation from last night has moved into the Bay of Campeche, and looks impressive for the moment but I doubt it will amount to much. When you have a strong system just to the SW of Mexico like Andres it's hard to get anything going near the Yucatan or BOC because the east Pacific system takes most of the energy. However, it is a fairly small system and wouldn't require very much energy to get a closed circulation going. If I were the NHC I would be mentioning this in the TWO today. I will be keeping a close eye on it.
I've seen some talk of a system near the Bahamas developing along the cold front east of Florida. A low will probably form, but it will not be tropical. Why? Because there's too much of a baroclinic zone, meaning that heat is being transported not consolidated. That is the basis of a cold-core system. There is no leeway for sub-tropical development either. For that you need a symmetric system, but this will be asymmetric.
The tail-end of the same front mentioned above is forecast to spawn an area of low pressure over the northern gulf coast during the next couple days, and as this happens the trough off the US east coast will be splitting, leaving a piece behind in the central Gulf of Mexico. This will try to pull the surface low SW over the gulf and we'll have to watch this to see if it tries to get something going. The GFS is still trying to bring a low NW out of the Caribbean in 4-5 days but as usual is too fast with it. We will have to watch for activity there though as the upper anticyclone builds over top of the area in 4-6 days. If anything these invasions into the GOM and Caribbean are signifying the northward push of moisture from the eastern Pacific in association with the MJO pulse that I've been talking about for several weeks, and if you remember I said there was a strong possibility of a tropical disturbance in the Bay of Campeche during this time, and today we have one =)
We shall see what happens!
Caribbean Visible Satellite: (click image for loop)
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