Archives 2000s >> 2013 Forecast Lounge

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cieldumort
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Tropical Storm Andrea Forecast Lounge
      #94351 - Mon Jun 03 2013 02:02 AM

In an interesting twist of the way weather can work, energies from former Hurricane Barbara, and the MJO pulse which helped spawn her, have sort of split in two, with a new dominant feature, a broad low pressure area, being tracked as Invest 91L.

Invest 90L, which was the remnant circulation of former Hurricane Barbara, is actually still being followed, as "Barbara."

To keep things simple, and in perspective, in the image below you can see the now teensy "Barbara" (formerly 90L) inland, or barely offshore along the extreme southwestern Gulf of Mexico, and large Invest 91L (the feature of some more interest now) centered a hop and skip to her northeast, around the northern Yucatan Peninsula.


Above: Barbara's remnant circulation (left) & Invest 91L (right)

Models have been percolating somewhat for several days, developing a tropical low of varying intensity this week in the general vicinity of either Barbara or 91L, and tracking it off to the northeast, across Florida, and generally up along, or either side, of the Gulf Stream.

The region is climatologically favored for development this time of the year, and the ways both x-Barbara and 91L have each been attempting to become something more are following a familiar, and sometimes successful pattern.

So far, it would appear that owing to 91L's much larger cyclonic envelope, Barbara may get completely absorbed within the next day or two. In the near term, the little bit of additional convection Barbara keeps blowing up seems to be acting to moisten the area around 91L somewhat, and thereby giving 91L some small shield from all of the dry air that has been pouring into the northern and western Gulf of Mexico.

Because there is still so much dry air in the Gulf, working in tandem with a considerable area of unfavorable upper-level winds, any tropical cyclone development of 91L will most likely be slow to occur, at least in the near term, as NHC has mentioned.

Regardless of further development, Invest 91L is and will continue to be a weather maker for Florida this week, increasing tropical weather related risks, as hours may turn to days of heavy rains with potentially strong winds and choppy waters.


Image credit: National Weather Service Tampa Bay

This is where to put mid to long range forecasts on 91L's potential for development, intensity, and forecast track. 91L-related longer range model output discussions are also appropriate here.

Edited to reflect upgrade to named storm status.

Edited by cieldumort (Wed Jun 05 2013 05:32 PM)


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MichaelA
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Re: Invest 91L Forecast Lounge [Re: cieldumort]
      #94352 - Mon Jun 03 2013 09:42 AM

I'm not seeing much support for significant development of this area/system due, mostly, to the upper level wind flow. Still, it's going to be a significant rain maker for peninsula Florida over the next few days. Still worthwhile to keep an eye on it, though. Strange things do happen from time to time.

--------------------
Michael

WU PWS

2020 “guess:” 15/8/3
2020 Actual 30/13/6


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doug
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Re: Invest 91L Forecast Lounge [Re: MichaelA]
      #94353 - Mon Jun 03 2013 11:40 AM

Agreed Michael. WV supports view that diffluence is the major contributor to the convection now occurring. That picture does not lead toward a conclusion that the system will be come tropical.

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doug


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GlenJohnson
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Re: Invest 91L Forecast Lounge [Re: doug]
      #94354 - Mon Jun 03 2013 12:21 PM

Let's hope this isn't the start of a strange year.

--------------------
Be civil to all; sociable to many; familiar with few; friend to one; enemy to none.
Benjamin Franklin
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JimB
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Re: Invest 91L Forecast Lounge [Re: GlenJohnson]
      #94355 - Mon Jun 03 2013 06:19 PM

Quote:

Let's hope this isn't the start of a strange year.




It was a strange winter and spring so if strange means less storms that would be sweet.


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MichaelA
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Re: Invest 91L Forecast Lounge [Re: doug]
      #94359 - Tue Jun 04 2013 11:49 AM

It looks to me that the shear may relax a bit today. Also, track guidance has shifted slightly westward with a possible landfall in the Big Bend region of Florida near St Marks in 48 - 72 hours. I also see that the intensity guidance has ramped up a bit indicating a TD or minimal TS in the same time frame. Only time and conditions will tell.

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Michael

WU PWS

2020 “guess:” 15/8/3
2020 Actual 30/13/6


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doug
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Re: Invest 91L Forecast Lounge [Re: MichaelA]
      #94360 - Tue Jun 04 2013 01:56 PM

I think the Sat. signature is better defined today with a broad exposed CoC and a consolidation of convection east of the center, which has temporarily pulled the rain away from the west coast of Florida. Earlier reports suggested that if the system was to organize it would be on Thursday; so, still plenty of time for more.

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doug


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MichaelA
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Re: Invest 91L Forecast Lounge [Re: doug]
      #94365 - Wed Jun 05 2013 10:18 AM

There appears to be a rather broad circulation centered near 25N - 88W on the Gulf RGB loop this morning that is West of the convection. That indicates that shear is still pretty much the dominate restriction for development of the system. It still looks like the shear might relax a bit today, though. The 50% chance for development seems to be accurate today.

--------------------
Michael

WU PWS

2020 “guess:” 15/8/3
2020 Actual 30/13/6


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cieldumort
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Re: Invest 91L Forecast Lounge [Re: cieldumort]
      #94380 - Wed Jun 05 2013 05:32 PM

Invest 91L is being upgraded this afternoon. Recon has found a reasonably well defined center of circulation, and maximum surface winds measured by the on board SFMR of at least 40 MPH, and we will have Tropical Storm Andrea.

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cieldumort
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Re: Tropical Storm Andrea Forecast Lounge [Re: cieldumort]
      #94381 - Wed Jun 05 2013 05:35 PM



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MikeCAdministrator
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Re: Tropical Storm Andrea Forecast Lounge [Re: cieldumort]
      #94383 - Wed Jun 05 2013 07:16 PM

Based on center relocation and the new model runs we may see the forecast track shifted a bit further east/south toward Citrus or Levy counties, which in the end doesn't mean much, since rain, the isolated tornado threat, and more rain will likely be the biggest impact. It could mean once over Florida the system has more time over water, however.

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doug
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Re: Tropical Storm Andrea Forecast Lounge [Re: MikeC]
      #94385 - Wed Jun 05 2013 08:36 PM

There is a large popup TStorm on the east side of the center and some other cells showing vertical development in other portions...is the shear lessening? If so intensity forecasts may have to be changed.

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doug


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cieldumort
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Re: Tropical Storm Andrea Forecast Lounge [Re: doug]
      #94395 - Thu Jun 06 2013 06:00 AM

What I like to call "net effective shear" has indeed been decreasing overnight.



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k___g
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Re: Tropical Storm Andrea Forecast Lounge [Re: cieldumort]
      #94406 - Thu Jun 06 2013 09:23 AM

Is the center beginning to wrap around and close off?

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cieldumort
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Re: Tropical Storm Andrea Forecast Lounge [Re: cieldumort]
      #94438 - Thu Jun 06 2013 07:01 PM

Tropical Storm Andrea made technical landfall in Dixie County, Fl. around 5:40 PM EDT today, June 6, with maximum sustained winds analyzed to be up to 65 MPH, and minimum pressure down to 993mb.

Andrea's strongest sustained winds were occurring in spots over water, but some strong gusts have been reported inland. Additionally, Andrea continues being a tornado maker.


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