TROPICAL CYCLONE FORMATION: NONE
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(T. F. “Storm” Walsh III)
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CURRENT 2016 TROPICAL CYCLONE TALLY:
TOTAL STORMS: 2
INTENSE HURRICANES: 0
Good day everyone!
The NHC in Miami declared BONNIE a post tropical cyclone this morning, and has issued it’s last public advisory. The following information was available on BONNIE in the 11:00 a.m. EDT advisory from the NHC:
11:00 AM EDT Mon May 30
Location: 33.4°N 79.8°W
Moving: ENE at 2 mph
Min pressure: 1012 mb / 29.88 in
Max sustained: 30 mph
Based on information contained in the NHC discussion, deep convection associated with BONNIE dissipated around 11:00 p.m. last night. Based on the lack of convection, and rising pressures, BONNIE has been designated post tropical. Based on analysis of the 12Z dynamic guidance, forecast steering layers maps, and out of respect, the ECMWF, I have to concur at the moment with the NHC forecast track, which appears to be a blend of the above, and in the middle of the consensus models.
The remnants of BONNIE are forecast to become and extra-tropical cyclone (mid latitude cyclone) as it becomes part of an approaching front in about 72-96 hours. Regeneration into a tropical cyclone is not forecast. In the meantime, the potential for heavy rain and flooding exists over portions of the Carolinas during the next 2-3 days.
This will be my last update on BONNIE.
Elsewhere, analysis of the global models indicates the models are split, and appears “they are not sure” on tropical development in about 7-10 days. The ECMWF and GGEM indicate low pressure over the extreme eastern GOMEX in around 7-10 days. I don’t usually bring up the NAVGEM (former NOGAPS) model, as it hasn’t been correct in the past 3-4 seasons. However, it wants to develop a large, weak area of low pressure (1006 mb) in the western Caribbean, east of Honduras in about 6-7 days. The GFS kind of hints at a broad area of low pressure near the same area (Gulf of Honduras), along with the FIM 8 and FIM 9, which indicate the start of development by day 5.
ECMWF 240 HOURS
GGEM 162 AND 168 HOURS
NAVGEM 144 HOURS
GFS 168 HOURS
Given the models are split, it’s difficult right now to determine which ones are correct. The GFS, ECMWF and ESRL PSD modeling indicate a lowering of pressure at 500 mb in about 48 hours around FL. After this, it appears the models introduce another trof split at approximately days 7-8, with one piece moving to the NE, and the other, well, that’s the question. Does the energy split and remain mainly over the GOMEX? Or is the split strong enough to send energy down as far as the Caribbean Sea? My thought on this is, and as I’ve stated before, the global models are NOT HURRICANE FORECAST MODELS, but models that take the information fed them, and produce a mathematical solution indicating what they THINK the state of the atmosphere is going to be at any certain time. Based on this, my thought is to handle this as I did Bonnie, in that the models indicated 500 mb pressure height falls 7-10 days out, but were from the E. GOMEX, to S. of Cuba, and over the Bahamas. I believe the global models did get initialization of the surface low correct, out to 7 days. So, near real time forecasting I believe, is going to be prudent on this. The models are evidently “sniffing out” and “hinting” at the possibility of development. What this should do, is give the forecaster a “heads up” in the sense of starting to pay attention around the GOMEX and W. Caribbean, say within the next 7 days. The models by nature, are not designed to “pinpoint” development of tropical storms and hurricanes.
Now, is development possible? Well, even thought the ECMWF and CMC indicate it in the GOMEX, unless the wind shear pattern takes a change (as we saw with Bonnie), the probability there is slim. However, wind shear is forecast to relax over the W. Caribbean by days 6-7, with a very favorable upper level 200 mb streamline pattern, indicating a rather large upper level anti-cyclone.
Analysis of the MJO Phase Diagrams today still seem to indicate a weak upward motion MJO signal to enter Octants or Phase 8 and 1 during the first week of June. This may become a little more likely, as the ECMF model seems to have trended toward the GFS solution, but a much weaker signal.
ECMF MJO PHASE DIAGRAM FORECAST
So the bottom line is, I will continue to monitor further model runs for any significant changes to pressure height falls and locations, wind shear, and the other parameters mentioned.
I will not have an update tomorrow, as I have to work. I intend on having an update on Wed.
Elsewhere, Tropical Storm formation is not expected during the next 7-10 days.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS