TROPICAL CYCLONE FORMATION: INVEST 97L (70%)
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(T. F. “Storm” Walsh III)
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CURRENT 2016 TROPICAL CYCLONE TOTALS:
TOTAL STORMS: 4
INTENSE HURRICANES: 0
StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 14-16
INTENSE HURRICANES: 3-4
Good day everyone!
The NHC has dropped INVEST 96L from the data base. The last model and BTK information was run at 06Z this morning.
Tropical Disturbance INVEST 97L has seen convection waxing and waning throughout the day. Recent satellite loop imagery indicates a slight increase in convection over the past few hours, and the disturbance appears to have become sightly more symmetric.
As of the 18Z ATCF BTK report, the following information was available on INVEST 97L:
2:00 PM EDT Sun Jul 31
Location: 14.8°N 64.8°W
Moving: W at 25mph
Min pressure: 1010 mb/29.83 in
Max sustained: 35 mph
Based on the information in the BTK product, 97L continues to move quickly to the west. Analysis of current and forecast steering layers maps indicates 97L should continue pretty much on a westerly track during the next 72 hours. The system is located to the south of the subtropical ridge, almost due south of the center of the ridge, as seen in the layer mean steering product. There is a strong flow from east to west at the current position of the system, and this flow extends out to around 75W. Once the disturbance enters the western Caribbean, we may see steering relax, and the disturbance could very well slow its forward motion. Thereafter, forecast steering maps indicate the other ridge center in the GOMEX will become centered near LA/TX in about 72-96 hours, which would allow for the disturbance to continue westward. However, given a slight weakness forecast over the SE TX area, there could be a slight gain in latitude. Based on this analysis, and analyzing recent runs of the global modeling, the system may very well come into the southern portion of Mexico in about 5 days, near latitude 20N. This seems to be the consensus at the moment, based on the 18Z Dynamic Model guidance, and in line with ECMWF, GFS and CMC GGEM models. Unless the current and forecast steering forecasts show any dramatic change over the next few days, even if this becomes a hurricane, the steering forecast shows only subtle differences between low layer and deep layer steering. The possibility does exist, based on the global models, the system could stall briefly along the coast of Mexico. Again, forecast steering will be reanalyzed on a daily basis over the next 3 days.
Currently, there is still a lack of a LLC, which may make intensity forecasts a little trickier. However, looking at satellite loop imagery, 97L appears to be getting “that look”. Although buoy data around the area does not indicate falling pressures at the moment, analysis of the 850 mb vorticity map indicates vorticity has become stronger at that level, and the area has become more compact. These two items combined COULD indicate the system may be trying to develop a LLC. This is only speculation at the moment on my part. Based on forecast motion, and current OHC, I do believe INVEST 97L may begin to show a little quicker structure improvement, and could begin to begin a LLC once it gets to around Longitude 75W.
OCEAN HEAT CONTENT
Analysis of the current wind shear product still indicates an upper level anticyclone over the system. The current shear forecast calls for this feature to remain over the system for the remainder of the forecast period (next 96-120 hours). Based on the SST’s and OHC, INVEST 97L COULD have the possibility of becoming a CAT 1 hurricane prior to moving over land. This is currently the thinking of the 3 accurate intensity models (SHIP, DSHIP, and LGEM. IF 97L can acquire a closed LLC within the specified time frame, I cannot rule this out at the moment. The NHC has increased the probability of cyclone development during the next 5 days to HIGH (70%) in the current Tropical Weather Outlook.
97L has excellent TPW surrounding it, which should aid in fighting off any surrounding dry air.
I will continue to monitor 97L for any significant changes, and I will try to update on a regular basis over the next 3 days.
Another large tropical wave should enter the east Atlantic tomorrow. At the moment, upper level winds are only marginal for development, however upper level winds are forecast to become a little more conducive during the next 2 days. Current and forecast steering at this particular time, indicate it may gain some latitude, and then be pushed back toward the west…not unlike what we saw with 96L. I will be monitoring this closely once it enters the eastern Atlantic.
Elsewhere, Tropical Storm formation is not expected during the next 5-7 days
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS