TROPICAL STORM FORMATION: IDA, AOI 20%
ALL forecasts contained on this site, are based on my analysis and knowledge of various forecast tools, including information contained in NHC products, and are not copies from any other entity.
*NOTE: In the TROPICAL STORM FORMATION line above, probabilities are for during the next 5 day period. My personal probability will be listed as either NONE, MONITORING or PROBABLE. This does not necessarily mean something will develop, but that certain forecast conditions are likely to be present, favoring development. Once NHC products become available, then the appropriate probability and percentage will be used.
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Current Storm Total for 2015:
TOTAL STORMS: 9
INTENSE HURRICANES: 1
U.S. LANDFALLS: 2
StormW’s Seasonal Forecast:
TOTAL STORMS: 8
INTENSE HURRICANES: 1
Good day everyone!
Tropical Storm IDA has been downgraded to a Tropical Depression. As of the 11:00 a.m. advisory from the NHC, the following information was available on the depression:
11:00 AM AST Thu Sep 24
Location: 20.2°N 44.9°W
Moving: NNE at 5 mph
Min pressure: 1005 mb
Max sustained: 35 mph
Based on my analysis of satellite loop imagery, the LLC still remains exposed 1-2 degrees west of the convective cloud deck. The LLC had been moving slowly to the NNE, however the most recent loop images indicate the center to be almost stationary, and may even be in the beginning of it moving toward the west once again. Or, this may be a semi loop, given that based on information in the NHC discussion, and analysis of forecast steering layers maps, the trof steering her NNE, is forecast to weaken, in which IDA will detach from its influence, with ridging forecast to build in once again for a brief time. Based on these products, this is supposed to occur within the next 12 -24 hours, and it is unknown to me at this period, whether this current motion will constitute a semi- cyclonic loop to a stationary motion, or if this is in fact, the forecast turn toward the west. In either case, based on the current steering layers forecast, IDA should follow the official forecast track, pretty much inline with the dynamic guidance consensus modeling.
12Z DYNAMIC MODEL GUIDANCE
Based on analysis of the recent shear product from CIMSS, the depression is undergoing approximately 30 knots of westerly shear. Analysis of the current wind shear forecast maps, and shear product from the HFIP model page, modeling appears in agreement that wind shear should decrease within the next 48 hours, to below 15 kts. Based on this premise, I have to concur with the NHC intensity forecast, in that IDA could again intensify to Tropical Storm status. The only item I can see that would not allow for this to occur, would be the massive amount of dry air that is over the system at the moment.
I will continue to monitor IDA during the next 48-72 hours for any significant changes.
Elsewhere, the NHC has added the forecast suspect area for the GOMEX into the 5 day Graphical Tropical Weather Outlook.
Global models have been hinting at this over the past few days, and I am currently monitoring the area near Honduras/Nicaragua. The area of interest is displaying some lower level cyclonic turning. Based on my analysis, this appears as if it may be associated with the system in the EPAC, located near the southern coast of central America. The current area of interest is forecast to move toward the NW during the next 72 hours, before entering the extreme southern GOMEX, just north of the NW tip of the Yucatan Peninsula.
Based on analysis of the global models, there is slight difference in timing as to when this develops, however the consensus appears to be around 120 hours in the forecast period from 12Z this morning. There is some discrepancy as far as location in the next 5 days with the global models, in which location may be just slightly further north than shown in the NHC graphic. Based on this, I am going to go with an average at the moment, and look for development in the mid Gulf, around 23N Latitude.
Analysis of the current wind shear product indicates upper level winds are not favorable for development at this time. However, based on analysis of the current 200 mb streamline forecast, this weather will be located in close proximity to an upper level anticyclone, but under the NE flowing streamlines. This pattern is forecast to remain over the Gulf of Mexico from the time this disturbed area enters the GOMEX, until either time of dissipation or landfall. Based on analysis of the global models, all of the models initiated should development occur, that said low may come ashore in an area between extreme western Louisiana coast, to western Mississippi coast. The outlier is the ECMWF which indicates the low opening to a wave, and affecting the central Texas coast. Based on analysis of the steering layers forecast maps, I have to discount the ECMWF track solution, as the steering layers forecast maps indicate a solution closer to the other global models.
Based on the shear forecast, the 200 mb streamline pattern will not be optimal for development, however based on the premise this should remain pretty much subtropical (based on the current forecast wind field, with maximum winds away from the center, and located to the NE of the low), the pattern may not be too detrimental for a subtropical system. The streamline pattern and 200 mb velocity values would tend to indicate an upper level outflow jet (RED ARROWS) to the NNE of the low, which would evacuate air away from the low to it’s NNE and NE. Based on this analysis, the pattern COULD be just favorable enough to possibly support a minimal, subtropical storm, however the majority of the models are indicating a tropical depression.
GFS 10M WIND FORECAST
This analysis is just a PRELIMINARY solution, given there is no organized system to analyze at this time. I will continue to monitor this area of interest during the next 72 hours for any significant changes.
I am not sure when I will have another update. It may not be until sometime late Sun.
Elsewhere, Tropical Storm formation is not expected during the next 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