TROPICAL CYCLONE FORMATION: INVEST 97L (90%)
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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!
Based on information continued in the 8:00 a.m. EDT Tropical Weather Outlook from the NHC in Miami, recent satellite and ship observations indicate that a surface circulation is becoming better defined, and the NHC has increased the probability of Tropical Cyclone development during the next 5 days to HIGH (90%).
As of the 12Z ATCF BTK report, the following information was available on INVEST 97L:
8:00 PM EDT Mon…Aug 01
Location: 15.8°N 71.7°W
Moving: W at 22 mph
Min pressure: 1007 mb/29.74 in
Max sustained: 45 mph
Based on my analysis of recent satellite loop imagery of various channels, INVEST 97L is becoming better organized. It is noted in satellite imagery that convection has increased and become more consolidated, and water vapor imagery indicates an expansion in the moisture field. Visible and RGB satellite loop imagery shows a “fanning out” of the upper level cirrus cloud deck, which is indicative of upper level outflow becoming established over the system.
The most recent wind shear product from CIMSS does still indicate an upper level anticyclone over the system, albeit somewhat displaced. The most recent satellite derived upper level winds map does indicate that outflow channels may be becoming established over the system (follow the red arrows).
CIMSS WIND SHEAR PRODUCT
The disturbance is currently moving toward the west, and has slowed its forward speed slightly. The disturbance is located to the south of the subtropical ridge, traveling around the southern periphery. I expect this motion to continue during the next 72-96 hours, with a possible fluctuation in track to slightly north of due west during the early portion of the period, as the system may sense the weakness in the ridge currently situated over the GOMEX, and then back toward the west in the latter portion. Analysis of current forecast steering layers maps pretty much backs this up, and is currently in concurrence with the 12Z Dynamic Model track guidance. Based on this, and current global model analysis, this system is still targeted to come ashore over Mexico IVO 20N Latitude. One exception I do have to current track thinking…after analyzing satellite loop imagery, a partially exposed circulation was noted to the WSW of the main area of convection. My thinking at the moment, which is a possibility, is there could be a center reformation underneath the strong convection. SHOULD this occur, then model guidance would most likely show a north shift, regarding initial position. All that this would mean is, the projected track would be shifted somewhat north, and landfall would shift somewhat further north, but still have an imparted westerly track, as the steering forecast still indicates for ridging to be maintained over the Gulf Coast region in the latter part of the aforementioned period. Pretty much, if this does finally close off a surface circulation, track guidance will become more accurate.
Based on the mentioned satellite loop images, the slight slowing of forward motion, and analyzed upper pattern, and given the premise that a closed LLC may develop, I believe we could see Tropical Storm EARL sometime later this afternoon/early evening. Based on forecast motion, I believe 97L may slow even slightly further, once crossing 75W. Given the high SST’s and OHC in that area, this may be where we see 97L get its act together a little faster.
Analysis of the forecast wind shear map indicates the upper level anticyclone to remain with the system throughout the period, albeit displaced somewhat if a shift north in the center of 97L occurs. Further analysis of the NOAA RUC TC DIAGNOSTIC models indicate average wind shear for 97L to remain below 10 knots during the next 72 hours.
Based on analysis of all these items, I believe 97L could very well attain CAT 1 Hurricane status before it’s all said and done. The more accurate of the intensity models only bring this to strong Tropical Storm strength, however a CAT 1 Hurricane may not be ruled out if all forecast conditions pan out.
Based on these diagnostics, we could see Tropical Storm WARNINGS go up for Jamaica, and a possible Hurricane WATCH for areas of the Yucatan Peninsula either sometime this evening, or sometime tomorrow.
The following is from the NHC TWO at 8:00 a.m. EDT:
Regardless of development, locally heavy rainfall and gusty winds, perhaps to tropical storm force, are likely along the southern coast of the Dominican Republic and Haiti today. Tropical storm conditions are likely to occur over Jamaica by this afternoon or evening, and could reach the Cayman Islands overnight. Interests in these areas and elsewhere in the western Caribbean Sea should continue to monitor the progress of this disturbance. For additional information on this system, see High Seas Forecasts issued by the National Weather Service.
I will continue to monitor the progress of 97L, and depending on this progress, may update again late this evening.
Elsewhere, another Tropical Wave has just exited the African continent. Upper level winds are currently marginal for development, and convection at the moment is limited. However, there is plenty of TPW just ahead of this feature, which is clearing out the SAL to the north and ahead of this wave. The current wind shear forecast indicates upper level winds may become favorable for development within the next 24-36 hours, with another upper level anticyclone being shown in the possible path. This wave will need to be monitored over the next 72-96 hours for signs of development.
I may not be able to update tomorrow, as I possibly have jury duty.
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