TROPICAL STORM FORMATION: DANNY, LOW (10%), MEDIUM (60%), MEDIUM (40%)
*SPECIAL NOTE: AT A LITTLE AFTER 9:00 P.M. THE ATCF AND NHC DESIGNATED THE WAVE WEST OF AFRICA INVEST 98L, LOCATED NEAR 13.3N;29.5W
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.
Please refer to the link for the Storm Prediction Center in the box at the top of the page, just below the Hurricane Hunter graphics.
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Current Storm Total for 2015:
TOTAL STORMS: 4
INTENSE HURRICANES: 1
U.S. LANDFALLS: 2
StormW Seasonal Forecast:
TOTAL STORMS: 8
INTENSE HURRICANES: 1
Good evening everyone!
Danny has been downgraded to a Tropical Storm. As of the 8:00 p.m. Intermediate Advisory, the following information was available on Danny:
Location: 15.6°N 54.1°W
Moving: W at 14 mph
Min pressure: 997 mb/29.44 in
Max sustained: 65 mph
NHC TRACKING MAP 5 DAY
The initial motion provided from a Hurricane Hunter aircraft earlier was 285 degrees, or WNW, however the storms LLC has been moving west over the past couple of hours. Based on current and forecast steering layers maps, I concur with the NHC, and I expect this motion to continue during the next 60-72 hours. Thereafter, as I have been forecasting for the past 2 days, a strong weakness in the subtropical ridge develops in the mid and upper levels, and a little weaker in the low level steering. Based on this, what may remain of Danny, should be drawn into a more NW motion, which is shown in the 5 day forecast track, and is also reflected in the dynamic track guidance models.
Based on my analysis of the forecast steering maps, this trof is a gradual development. However, either the remnant or depression Danny, will be steered in the lower levels. Given this, and with the look of the current forecast track from the NHC, whatever feature is left should mover over the northern Bahamas area, or slightly west of the northern Bahamas, in between the Florida peninsula, and the Bahamas, before being turned north then NE. Again, this is based on the CURRENT run of the steering forecast, which is valid for 00Z this evening. There is always the chance for subtle changes, if steering fluctuates between now and then. However, at the moment, this seems to be the most plausible scenario at the moment.
Satellite loop images indicate that the LLC (Low Level Circulation) of Danny has become exposed to the SW of the mid and upper level circulation. This is being caused by SWLY wind shear on the order of 20-25 knots over Danny.
Water vapor loop imagery indicates a vast amount of dry air ahead of Danny, and outflow boundaries noted in RGB satellite loop imagery that Danny is beginning to ingest this dry air. Based on the current wind shear forecast, upper level winds are forecast to remain unfavorable for any recovery. Based on these factors, I concur with the NHC intensity forecast, which calls for Danny to continue gradual weakening. By the end of the 5 day forecast period, Danny is forecast to be downgraded to a depression.
Currently, Tropical Storm Watches are in effect for portions of the northern islands.
From the NHC in Miami:
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Watch is in effect for…
* Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and Anguilla
* Saba and St. Eustatius
* St. Maarten
* Guadeloupe, St. Barthelemy, and St. Martin
A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.
Interests elsewhere in the U. S. and British Virgin Islands, Puerto Rico, and the Dominican Republic should monitor the progress of Danny. Additional watches or warnings may be required for portions of these areas tonight or Sunday.
I will continue to monitor Danny during the next 72-96 hours for any significant changes to the steering pattern, and will try to have an update sometime tomorrow. If not, my next update will be sometime on Tuesday.
Elsewhere, the NHC still indicates 3 areas of interest in the 5 day Graphical TWO.
The area north of Bermuda was designated INVEST 97L yesterday evening. The NHC has lowered the probability of development during the next 5 days to LOW (10%). Upper level winds are not conducive for development at this time. Although the NHC indicates there is some potential, this area is still associated with an upper level low, and is taking in dry air, which is plainly noted in water vapor imagery. Based on this, I believe chances will be lowered again within the next couple of days. This area should move to the north, then NE as it becomes merged with a front.
A Tropical Wave located near 14.5N;28.0W has become slightly better organized today. This wave is moving toward a westerly direction at around 25 mph. Based on my analysis of the steering layers forecast, I expect this motion to continue during the next 72-96 hours, and coincides the the current NHC projected motion in the 5 day Tropical Weather Outlook. Thereafter, the steering forecast will have to be reanalyzed to detect any changes that may occur. As a general rule, I do not go out beyond 72-96 hours, as steering sometimes can change rapidly.
The current wind shear map of the EATL indicates a small, elongated upper level anticyclone over the wave, and the shear forecast calls for this feature to move in tandem, not unlike what we just saw with the development of Danny.
Some dry air is note IVO of the wave, however conditions appear pretty similar to when we saw Danny develop. IF convection can increase, the now warmer SST anomalies in the path may aid the wave in mixing out the dry air.
Based on these parameters and the fast forward speed of the wave, development should be slow to occur. I will continue to monitor this feature during the next 72-96 hours for any significant changes.
Another wave is forecast to move off the African coast in the next few days. The NHC has designated a MEDIUM (40%) probability for development during the next 5 days. Upper level winds are forecast to become favorable for this area to slowly develop. Development if any should be slow, due to drier air around this. This feature should move toward the WNW initially, and based on my analysis of forecast steering, a sharp weakness develops in the subtropical ridge, and is forecast to steer this feature to the NNW in about 96 hours, then out to sea. I will be monitoring this for any changes.
Have a blessed evening!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST / SEVERE WEATHER SPECIALIST MEMBER WEST CENTRAL FLORIDA AMS