TROPICAL CYCLONE FORMATION: INVEST 97L (90%)
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(T. F. “Storm” Walsh III)
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CURRENT 2016 ATLANTIC TROPICAL CYCLONE TOTALS:
TOTAL STORMS: 12
MAJOR HURRICANES: 1
StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 13-15
INTENSE HURRICANES: 3-4
Good day everyone!
INVEST 97L continues to become better organized this morning. Satellite imagery this morning indicates a more tightly wound circulation, however some wind shear earlier has displaced the area of heavy convection to the NE of the center. As of the 12Z ATCF BTK product, the following information was available on INVEST 97L:
8:00 AM EDT Tue Sep 27
Location: 11.3°N 52.5°W
Moving: W at 17 mph
Min pressure: 1008 mb / 29.77 in
Max sustained: 35 mph
Based on the information, 97L has maintained a westerly, to just slightly north of due west, having traveled 0.5 deg north, and 2.9 deg. west over the past 12 hours, with forward speed averaged out to 17 mph.
While the satellite presentation has improved greatly, the system is tilted slightly to the ENE, based on recent vorticity maps. The latest wind shear product does indicate that wind shear has relaxed somewhat, and the upper level anticyclone which is forecast to move in tandem pretty much for the life of the system, may be trying to become established. The current upper level winds product does show an outflow channel established to the west, and clockwise to the north and NE. The NHC has designated a HIGH (90%) probability of cyclone development during the next 48 hours:
If this trend continues, the possibility exists we could have a tropical depression by late this evening, or sometime tomorrow morning.
Based on my analysis of the current wind shear forecast from both the GFS and ECMWF both in shear value and 200 mb streamline pattern, forecast SST’s, Ocean Heat Content, and PWAT values, I see nothing in the way at the moment, to prohibit further organization and strengthening of this system over the next 96-120 hours, except possible slight land interaction with the northern South American coast. Depending on actual track thereafter, there could be temporary weakening should the system cross over Hispaniola or Cuba later in the period. Regardless, in the short term, based on should the parameters mentioned come to fruition, I have very reason to believe we will see tropical storm Matthew in the Caribbean within the next 36-48 hours. Track will be discussed next, but I needed to mention, in addition to the above, the 200 mb streamline pattern and low shear values that are forecast, should provide a very favorable environment for intensification, especially when the system slows down. Also, the forecast is calling for the MJO to be in place during the latter part of the first week of Oct., through to almost the second week of Oct. The forecast also calls for favorable 200 mb velocity potential anomalies in the same time period. Put it all together if it all pans out, it doesn’t get much better than that for a conducive environment. What this is leading to is, SHOULD this system take a track further west (ECMWF), and all of these favorable parameters come together, this system could have the potential to become a category 4 to category 5 hurricane, based on the Maximum Potential Hurricane Intensity product, as this track would tend to place the system over some EXTREMELY high Ocean heat content. Even if this intensity does not occur, I am not ruling out a MAJOR HURRICANE with this.
Based on analysis of the current steering layers forecast maps, and having poured over every available model I have at my disposal, should the models remain consistent and the forecast pattern be accurate, I currently see 2 scenarios regarding this system. The global models which indicated this system recurving out to sea, making that quick turn north, have now come more toward the left, or west with the future track. The outlier, ECMWF has shifted more over Cuba, and closer to the Florida peninsula, and the majority of the ECMWF Ensemble members have shifted left over the past 24 hours, indicating a possible Gulf of Mexico threat. This is due to the models recently indicating the 500 mb trof slowing down, with a little more ridging remaining north of the system. Looking at the setup, the system would have a tendency to move more NW longer, before recurving. So at the moment, here’s what we are pretty much looking at right now. The future track, albeit a little more certain, but still uncertain due to these variables, will all be determined by the strength of the system, it’s forward sped, and actual timing of the ridge/trof pattern. Right now, based on my professional opinion, if future Matthew remains a weaker system in the Caribbean as it gets to the central Caribbean, then the most likely solution will be what the ECMWF model is showing. IF the system is stronger, then the chances of it feeling the ridge weakness becomes greater, and is more likely to take a track depicted by the GFS. Even with the GFS track, the model has shifted west quite a bit, and it is showing once the system begins to re-curve, it could make landfall around the Cape Cod area. The CMC GGEM has come left as well, and brings it to NC. The NAVGEM doesn’t go out as far in the forecast period, but shows a Hurricane Matthew over eastern Cuba.
The bottom line here…the U.S. may not be out of the woods anymore, but as I’ve stated time and again, the models will have better solutions, once 97L can close off a well defined surface low, and then base solutions on how fast or slow the system develops. We should also have better information later today as a Hurricane Hunter aircraft is scheduled to fly into the area later today. Regardless, (the following from the NHC) interests in the eastern and central Caribbean Sea, including the northern coast of South America, should monitor the progress of this disturbance, since warnings and watches could be required at any time. Regardless of whether the system is a tropical wave or tropical cyclone, heavy rains and wind gusts to tropical storm force are expected to spread over the Windward Islands and portions of the southern Lesser Antilles, beginning tonight and continuing into Wednesday.
I also strongly recommend given the uncertain variables affecting future track from the Caribbean, residents along the Gulf Coast states from MS, eastward to along the eastern seaboard closely monitor the progress of 97L, and as just a precaution, because it’s never too early to do so, review their hurricane preparedness plans. Again, I want to reiterate, this is not to scare people, or to even say there will be a definite hit on the U.S., but with the information this morning, the probability has increased.
Should this by chance become a threat for the U.S., I will most likely do special updates at such a time, after I arrive home from work, should the need arise. It may be later at night, but if God gives me the strength after working all day, I’ll try to keep you update
Elsewhere, Tropical Storm formation is not expected during the next 5-7 days.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS