ATL: HERMINE - Post-Tropical - Discussion

[Nimbus]

Classic reformation with the inflow pulling in through the Mona passage and Hispaniola disrupting the low level circulation. Land interaction delayed development at least a day, I'll take it!

The shear isn't that bad near the center of that stacked anticyclone and some models are closing off a low level center along the northern coast of Hispaniola fairly soon, others seem to be dragging a less organized mess all the way to the Florida straits. With all the vorticity in the area I doubt they have a good handle on the shear forecast beyond 48 hours. That could vary a lot depending on unknowns like storm strength.

[northjaxpro]

While that outflow channel is creating some impressive ventilation, its still seems clear that its getting suppressed on its north side. Frank, while this supressed appearance occuring along the northern quadrant of the LLC might be imparted by the blocking mid level ridge to its north, would'nt you guess that the same stacked upper level anticyclone might also be and continue to infringe some form of northerly shear as well?

Yes, I would I think that would be continuing out there as well.Just another variable tossed into this complex scenario.

[NDG]

One thing to watch out for is that 99L will be moving through the Bahama Islands which are flat and surrounded by very warm waters, forecasted by both the Euro and GFS to move very slowly starting tonight through Sunday night before reaching the Keys or SE FL coast. I estimated the forward speed at only 6.4 mph averaged in 3 days. Both the Euro and the latest GFS show it come to almost a crawl by Monday. All 99L has to do is find a sweet spot in the upper levels to strengthen fairly fast and we have seen this numerous times in this area before.

[Bad_Hurricane]

The NOAA43 aircraft is on the way into AL99. They'll be there about a half hour.



Flight track:

[Bad_Hurricane]

[NDG]

[Blown Away]

One thing to watch out for is that 99L will be moving through the Bahama Islands which are flat and surrounded by very warm waters, forecasted by both the Euro and GFS to move very slowly starting tonight through Sunday night before reaching the Keys or SE FL coast. I estimated the forward speed at only 6.4 mph averaged in 3 days. Both the Euro and the latest GFS show it come to almost a crawl by Monday. All 99L has to do is find a sweet spot in the upper levels to strengthen fairly fast and we have seen this numerous times in this area before.

The model slow down after day 3 is really tricky as 99L nears SFL... I guess the GFS gets some props, it has not waivered from a slow down... Looks like TAFB has 99L moving NW towards Upper Keys, do you think a stronger system will get more poleward at that point??

[NDG]

One thing to watch out for is that 99L will be moving through the Bahama Islands which are flat and surrounded by very warm waters, forecasted by both the Euro and GFS to move very slowly starting tonight through Sunday night before reaching the Keys or SE FL coast. I estimated the forward speed at only 6.4 mph averaged in 3 days. Both the Euro and the latest GFS show it come to almost a crawl by Monday. All 99L has to do is find a sweet spot in the upper levels to strengthen fairly fast and we have seen this numerous times in this area before.

The model slow down after day 3 is really tricky as 99L nears SFL... I guess the GFS gets some props, it has not waivered from a slow down... Looks like TAFB has 99L moving NW towards Upper Keys, do you think a stronger system will get more poleward at that point??

The weird thing is that the GFS shows it much weaker than the latest 0z Euro and still tracks it northward towards the Big Bend area of FL. At this point it wouldn't surprise me either way, something to keep in mind is that both the Euro and GFS have underestimated the ridge on their medium range from time to time so I wouldn't write it on stone that northward turn after S FL just yet.

[NDG]

URNT15 KWBC 250937
NOAA3 WAWXA AL99 HDOB 18 20160825
092800 2029N 06936W 6947 03232 0077 +118 +057 090020 020 025 000 00
092830 2029N 06934W 6946 03232 0076 +117 +066 093020 020 026 000 00
092900 2029N 06932W 6947 03230 0075 +116 +077 090019 019 029 000 00
092930 2029N 06930W 6945 03231 0073 +120 +046 086019 020 027 000 00
093000 2029N 06928W 6945 03231 0073 +121 +041 087020 020 030 000 00
093030 2029N 06925W 6946 03228 0072 +120 +046 086019 020 031 000 00
093100 2029N 06923W 6946 03228 0073 +117 +060 089016 017 031 000 00
093130 2029N 06921W 6947 03225 0072 +115 +071 091015 016 032 000 00
093200 2029N 06919W 6946 03228 0071 +117 +062 089016 017 030 000 00
093230 2029N 06917W 6945 03227 0067 +122 +048 087018 018 030 000 00
093300 2029N 06915W 6945 03228 0067 +121 +059 093018 018 031 000 00
093330 2029N 06913W 6947 03227 0069 +118 +076 100016 017 032 000 00
093400 2029N 06911W 6947 03227 0071 +117 +081 104015 016 032 000 00
093430 2030N 06908W 6946 03228 0076 +111 +091 104014 015 031 000 00
093500 2030N 06906W 6947 03227 0081 +107 +095 109013 013 031 000 00
093530 2030N 06904W 6946 03227 0084 +105 +083 118013 014 032 000 00
093600 2030N 06902W 6946 03226 0076 +113 +073 122014 016 031 000 00
093630 2030N 06900W 6946 03228 0078 +112 +068 127016 017 031 000 00
093700 2030N 06858W 6947 03227 0080 +110 +070 124016 017 030 000 00
093730 2030N 06856W 6947 03227 0081 +110 +070 119018 019 030 000 00

[NDG]

Based on the NOAA Recon this morning the low level vorticity appears to be near 20.5N & 69.5W

[jlauderdal]

One thing to watch out for is that 99L will be moving through the Bahama Islands which are flat and surrounded by very warm waters, forecasted by both the Euro and GFS to move very slowly starting tonight through Sunday night before reaching the Keys or SE FL coast. I estimated the forward speed at only 6.4 mph averaged in 3 days. Both the Euro and the latest GFS show it come to almost a crawl by Monday. All 99L has to do is find a sweet spot in the upper levels to strengthen fairly fast and we have seen this numerous times in this area before.

The model slow down after day 3 is really tricky as 99L nears SFL... I guess the GFS gets some props, it has not waivered from a slow down... Looks like TAFB has 99L moving NW towards Upper Keys, do you think a stronger system will get more poleward at that point??

the stronger systems tend to go poleward which is what made the gfs solution the last few days so troubling...weak system heading into a stout ridge albeit the gfs saw a weaker ridge than the euro but it was still a healthy ridge...track seems decent at this point...intensity completely different story, we could have a vigorous wave coming into the peninsula or a hurricane 1-2-3 who knows, there is plenty of potential but you dont take potential to the bank and right now one could say the system is weaker than 24 hours ago..saw people buying water and other supplies yesterday, thats a good thing because the florida hurricane season is just getting underway aug 15 to nov 1....i started the generator yesterday as did several others on the street...starting the generator to keep the hurricanes away has worked ever since Wilma so why stop now

side note: healthy train moving through palm beach county this morning on the easterly flow...been lightning in FLL since 3 am

another day of bantering of what might or might not be happening with this potential player

J

[NDG]

I bet we will see a naked swirl in the morning, convection north of Hispaniola is starting to collapse as the mountains of Hispaniola must be starting to cut off the inflow to those storms and the convergence starts shifting to the southern coast of the Island.

[CourierPR]

I bet we will see a naked swirl in the morning, convection north of Hispaniola is starting to collapse as the mountains of Hispaniola must be starting to cut off the inflow to those storms and the convergence starts shifting to the southern coast of the Island.

I would assume the system would improve later as it begins to pull away from the island.

[jlauderdal]

there is a plane out there now....i doubt they find much at this point..the Hispaniola effect is in force right now which is no surprise really

[CourierPR]

there is a plane out there now....i doubt they find much at this point..the Hispaniola effect is in force right now which is no surprise really

Well, apparently they have found lower pressures than yesterday.

[SouthFLTropics]

there is a plane out there now....i doubt they find much at this point..the Hispaniola effect is in force right now which is no surprise really

It would appear to my untrained eye that the frictional forces of the Hispaniola land mass might be pulling the LLC WSW and into the island. It's almost like the island reached out and grabbed it and sucked it in.

[BobHarlem]

http://www.ndbc.noaa.gov/radial_search. ... t=A&time=4

From overnight, only thing that stands out there is a 69/70 knot ship report with a falling 29.65 (1004mb) pressure 20.80N 69.30W from earlier this morning (this seems out there), some 35 knot ship reports though.

[jlauderdal]

there is a plane out there now....i doubt they find much at this point..the Hispaniola effect is in force right now which is no surprise really

It would appear to my untrained eye that the frictional forces of the Hispaniola land mass might be pulling the LLC WSW and into the island. It's almost like the island reached out and grabbed it and sucked it in.

its possible...these systems are usually good at finding open water but this thing is so weak and Hispaniola has a history of finding ways to destroy systems..there are multiple ways for Hispaniola to win

[Nederlander]

It would appear to my untrained eye that the frictional forces of the Hispaniola land mass might be pulling the LLC WSW and into the island. It's almost like the island reached out and grabbed it and sucked it in.

Vis will tell the tale shortly.. I feel like we will have a naked llc again and what you are seeing is mid level vort...

[Nederlander]

There appears to be some low level circulation north of DR and NW of the convection.. right around 20.6N 70.7W. Not sure if that's our LLC, but I see a swirl there..