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Tropical Global Model Runs Discussion 2017

Another area out in the middle of nowhere popped up.

An area of low pressure is forecast to form on a frontal boundary in
a few days about 900 miles southwest of the Azores. This low
could acquire some subtropical or tropical characteristics early
next week while it remains nearly stationary over the northeastern
Atlantic Ocean.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.
 
GFS brings something that forms between Bermuda and Puerto Rico into Florida from the east next weekend
 
Brent said:
GFS brings something that forms between Bermuda and Puerto Rico into Florida from the east next weekend
Click to expand...

This area has its genesis per the JMA (I know it isn't one of the more accurate models...so this is more for the record and being mentioned due to some other models having had similar features) on Tue between Bermuda and P.R. and hits S FL from the east as what looks like a TD next Sat AM followed by a slow move further west into the Gulf. This may turn out to be the next area to watch for US interests in this continuing Augustlike pattern.
 
^Have there been any TCs hit FL from the Atlantic side traveling largely east to west in mid Oct or later? Actually yes though not many. But there just having been some is enough to believe something similar would have a slight chance to happen in about a week due to the persistent ridging to the north along with the model hints.

Past occurrences on record of TC hits on FL from east (not either a Caribbean or Gulf origin) mid Oct or later since 1851: 7 times or about once every 24 years on average meaning not so rare that this possibility shouldn't be considered. (Also, a few weak hits may not be on record, especially pre-1900). Here are the 7 on record:

1. 1859: TS landfall Oct 17 http://weather.unisys.com/hurricane/atlantic/1859/7/track.gif

2. 1906: TD near landfall Oct 17
http://weather.unisys.com/hurricane/atlantic/1906/9/track.gif

3. 1935: cat 2 H landfall Nov 4
http://weather.unisys.com/hurricane/atlantic/1935/7/track.gif

4. 1941: TS indirect hit Keys Oct 17 (and later landfall W FL)
http://weather.unisys.com/hurricane/atlantic/1941/6/track.gif

5. 1946: TS landfall Nov 1
http://weather.unisys.com/hurricane/atlantic/1946/7/track.gif

6. 1984: TD landfall Oct 26
http://weather.unisys.com/hurricane/atlantic/1984/17/track.gif

7. 1985: Kate cat 2 H indirect hit Keys Nov 19 (and later landfall W FL)
http://weather.unisys.com/hurricane/atlantic/1985/KATE/track.gif
 
About to have TD 17 out by the azores doesn't seem to have much of a future it's not the storm talked about above

Or not, the best track says so but nothing at 11 lol
 
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GaWx said:
This area has its genesis per the JMA (I know it isn't one of the more accurate models...so this is more for the record and being mentioned due to some other models having had similar features) on Tue between Bermuda and P.R. and hits S FL from the east as what looks like a TD next Sat AM followed by a slow move further west into the Gulf. This may turn out to be the next area to watch for US interests in this continuing Augustlike pattern.
Click to expand...

^This entity, on the higher res 6Z GFS, develops Monday night and at hour 66 (Tue evening) it is already a compact 1008 mb low only 750 miles SSW of a 1023 Bermuda high. It appears to already be either a STD or a TD by then. The run doesn't show strengthening but it moves steadily westward underneath a persistent strong 500 mb high and maintains itself as a compact surface low that reaches Melbourne amidst light 200 mb winds north of a shear zone as what looks like a 1013 mb TD at hour 174 (Sunday AM 10/15).

6Z GEFS: strongest signal of any GEFS yet with almost all members forming a surface low Mon night that moves steadily WNW to W and makes it to just a few hundred miles E of the N Bahamas Wed night. Considering that the lower resolution members are in many cases then down to 1002-6 mb not much more than 1,000 miles S of a 1030 NE US surface high, a good number of these members are quite possibly at TS strength. Some of these members stall while others come into the SE US, mainly FL, between Fri and the subsequent Tue (10/13-17).

Edit: I expect this potential to start getting mentioned in the TWO by tomorrow assuming continued model support.
 
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The 12Z GFS higher resolution has its strongest run by far so far with a 1000 mb low Tue night (hour 66 for 6Z Wed) 500 miles N of the Lesser Antilles. I'm assuming this higher res GFS run is overstrengthening it but the comparison to earlier runs is interesting nonetheless. This run is further north than the 6Z GFS and weakens it next weekend NE of the N Bahamas. Meanwhile, the often crazy/unreliable CMC has a 1004 mb TC hit on SE FL on Saturday (10/14).
 
12Z GEFS: 5 members hit FL Fri-Sat, including one at 1001 mb (likely a TS) and another 3 hit Monday for a total of 8 of 20 (40%). Folks, keep in mind that the members are run at a lower resolution than the operational.

The 12Z GEPS also hits FL with about 1/3 of its members (~7) between Fri and Sun.

The 12Z Euro is again relatively quiet and well south with a highly sheared weak low near the N coast of Cuba though it is slightly stronger than its prior run. Keep in mind that sometimes the Euro misses geneses. Remember that it was very late to the GFS party of developing the noname near the FL Keys just a few days ago. Then again, the GFS and especially the CMC often overdo geneses. So, we'll see.

Edit: Today's 12Z JMA day 6 is much weaker and further SW than yesterday's 12Z JMA day 7, which had what appeared to me to be a TD over S FL.

Edit #2: The 12Z EPS is also pretty quiet though not quite as quiet as the 0Z EPS. I do see one sub 1004 member on this run vs none on the 0Z. But there are 50 members.
 
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GaWx said:
What in the wide, wide world of sports is a going on here? Today's 18Z GEFS is the 3rd 18Z GEFS in a row showing numerous members with western Caribbean TC genesis in the first week of October!! No other GEFS run in between these 3 runs has had much of anything! That is really, really strange.
Click to expand...

I'm bumping this because of deja vu from just over 3 weeks ago. The season may not be done just yet for the Conus. For those who want to see modeled action, the 18Z GEFS once more did not disappoint as it went batshoot crazy! This run is even more active than yesterday's Happy Hour GEFS, which itself had been the most active by far for late month.

Out of 20 members, I counted a whopping 12 Hs. Most members have a TS+. This run is reminiscent of the GEFS/EPS runs leading up to Nate that had numerous members hitting FL with a TC during 10/7-10. It turned out that the 10/7-10 timeframe was dead on but Nate went ~400 miles west of the consensus of these FL pen. hitting members.

This run has member geneses mainly within 10/25-8. One H hits W FL 10/28, another hits Keys/S FL 10/29, and a 3rd one hits Keys/SW FL 10/31 before then hitting the Panhandle 11/1. In addition, there are FIVE Hs at the end of the run on 11/1 in the NW Caribbean moving in a direction that could later lead to a FL hit.

The only thing keeping me from considering this as a very strong signal is that it is an 18Z GEFS run, which was the most active by a good margin around Nate's time and is doing it again. Especially when this far out, the predictable pattern is for 18Z to be the most active, 6Z least active, and 0Z/12Z in between. As it turned out, those active 18Z GEFS were onto something. Are they this time?

I think I need a drink after this run.
icon_wink.gif
 
The threat for a TC genesis during 10/24-29 in/near the NW Caribbean continues to increase. There are no fewer than 7 of 20 members of the 0Z GEFS with a H and most members with a TS+. One H hits S FL 10/30. Several TSs hit FL and several Hs lurk in the NW Caribbean at the end of the run. No, this isn't quite as active as the often most active 18Z GEFS but it is much more active than any non-18Z GEFS run has been for late Oct.
 
Ahh, the Happy Hour GEFS, everyone's favorite GEFS run and the run that inspired the expression, "we toss". Well, it didn't overdo the drinking this time. I notice that it has slipped since yesterday as regards most members' genesis times to 10/28-31 vs yesterday's 18Z GEFS being mainly 10/25-8. Also, there are not as many TS+ or Hs. In addition, whereas yesterday's had 3 H hits on FL along with 5 member Hs lurking in the NW Caribbean at the end of the run, this had zero direct TC hits on FL because they mainly move ENE over central or E Cuba south of FL. Apparently, they are assuming a deeper trough/cold front vs yesterday. In summary, much less threatening for FL vs yesterday.

Any opinions as to this having the right idea?
 
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Son of a gun, the 0Z GEFS brought back the FL threat that the two prior runs had taken away! SW or W FL is hit by three strong TSs or Hs with W Caribbean geneses (out of 20 members) on these days: 10/29, 10/30, and 11/1. Also, one is threatening to hit as of the end of the run on 11/3. A total of ~7 Hs form from the 20 members. Many members do stay south of FL still. Per history, FL has been hit by a TC with W. Caribbean or GOM genesis 8 times during 10/26-11/5 since 1851. After 11/5, the threat from the WC/GOM goes way down per history.

The 0Z Euro has basically nothing.
 
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Don't look now but the 0Z Euro has a strong TS (999 mb) in the NW Caribbean at hour 192!

This becomes a H soon afterward in a very low shear environment and is moving NE day 10 still in the NW Caribbean. It is hard to say if that would later hit the Keys/S FL. It could still pass south of there from this position.

Edit: The 0Z EPS has 2 members which directly hit FL 11/1-2, one Keys and S peninsula and other Big Bend.
 
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The relative rise in surface pressures over the contiguous US in response to the infiltration of large Cp air masses, in combination w/ the forthcoming passage of a CCKW favor some tropical cyclogenesis in the western Caribbean after this week...
ecmwf_mslpaMean_us_1.png

ecmwf_mslpaMean_us_6.png

Screen Shot 2017-10-22 at 9.55.51 AM.png
 
1. A non-tropical area of low pressure is forecast to form during the
next couple of days a few hundred miles south-southwest of the
Azores. This low could acquire some subtropical characteristics
by the middle of next week while it moves generally northeastward.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.
 
The CMC is playing with this one.
1. An elongated area of low pressure that extends from southwest to
northeast across the central Caribbean Sea is producing a large area
of disorganized shower and thunderstorm activity. While strong
upper-level winds are expected to prevent any significant
development, heavy rainfall is possible over portions of the
northwestern coast of Colombia, Hispaniola, and Puerto Rico during
the next few days while the low meanders over the central Caribbean
Sea and interacts with an upper-level trough.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...10 percent.
 
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