TROPICAL STORM FORMATION: T.D. ELEVEN, 99L (30%)
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*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, for 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!
One depression gone…another one develops. INVEST 98L has been upgraded to a Tropical Depression…designated T.D. ELEVEN late yesterday evening. As of the 11:00 a.m advisory from the NHC, the following was available on T.D. ELEVEN
11:00 AM AST Mon Sep 28
Location: 27.8°N 69.6°W
Moving: WNW at 5 mph
Min pressure: 1006 mb / 2971 in
Max sustained: 35 mph
The depression has been undergoing 20-25 knots of wind shear, which has left the LLC exposed just on the NNW edge of the convection and slight banding features, based on current satellite loop imagery. Based on the current winds shear forecast 200 mb streamline product, and the GFS / UKMET shear prognosis from the HFIP modeling, I’m forecasting upper level winds to become somewhat ore favorable in about 36 – 42 hours from 06Z, based on the 200 mb streamline forecast showing an improvement in upper level outflow, albeit marginal, and reduction in shear magnitude averaging 15-16 knots. Based on this premise, if the modeling is accurate, I agree with the NHC intensity forecast, and the depression could be upgraded to Tropical Storm Joaquin. Shear magnitude at the moment is forecast to remain somewhat favorable up to approximately 72 from 06Z this morning, so this is a short window of opportunity for this scenario to occur. Thereafter, the system will become sheared once again, and other environmental factors would preclude further intensification.
RGB satellite loop imagery displays the LLC very well, and analysis reveals the WNW motion in the NHC advisory. Based on forecast steering layers analysis, I expect this motion to continue for the next 36-42 hours, prior to moving more toward the NW. This is reflected in the NHC forecast track, and is inline with the ATCF 12Z dynamic guidance.
Elsewhere, INVEST 99L remains a sheared system this morning. In fact, latest satellite loop imagery seems t0 indicate the LLC has become much less defined than it was a few hours ago.
The area is still under 20-30 knots of wind shear, and the current wind shear forecast indicates shear to remain in place. I do not foresee this becoming a depression.
INVEST 99L SHEAR MAP
The INVEST is moving toward the NNE at around 8-10 mph, and I expect this motion to continue during the next 72 hours. This is indicated in the 12Z dynamic guidance. However, based on recent satellite motion, I prefer a track just right of the TVCN/TVCC consensus.
The main hazard appears to be the possibility of heavy rainfall over portions of the west Florida coastline during the next 48 hours. Current Doppler radar information indicates total storm precipitation values of 2-4 inches in the heaviest rain areas.
The following is the 72 hour precipitation totals forecast from the NAM and GFS models
Elsewhere, a large tropical wave is located in the central Atlantic. Upper level winds are currently somewhat favorable over the area, however the current wind shear forecast indicates upper level winds to become unfavorable during the next 24-36 hours. I am not expecting development of this area.
Global models continue to hint at a weak coastal storm developing off the eastern seaboard in about 3-5 days. Analysis suggests that the remnant of T.D. ELEVEN, along with energy from INVEST 99L will trigger this. I will continue to monitor the area during the next 72 hours.
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