TROPICAL DEPRESSION IDA / INVEST 98L / INVEST 99L FORECAST SYNOPSIS…ISSUED 11:15 A.M. EDT…SEP. 27, 2015

TROPICAL STORM FORMATION: IDA, 98L (50%), 99L (30%)

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, for 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: 9
HURRICANES: 2
INTENSE HURRICANES: 1
U.S. LANDFALLS: 2

StormW’s Seasonal Forecast:

TOTAL STORMS:             8
HURRICANES:                   3
INTENSE HURRICANES: 1

Good day everyone!

The NHC is still following Tropical Depression IDA.  The following information was in the 5:00 a.m. advisory:

5:00 AM AST Sun Sep 27
Location: 24.3°N 48.0°W
Moving: W at 5 mph
Min pressure: 1007 mb
Max sustained: 30 mph

IDA is now moving west, and I expect this motion to continue for the next 72-96 hours.

NHC TRACKING MAP
084402W_sm

Very briefly, satellite imagery shows that the LLC of the depression is exposed and now elongated.  Upper level winds are forecast to increase.  I pretty much still expect the depression to degenerate within this time period, if not sooner, in agreement with the NHC forecast discussion.

IDA FLOATER SATELLITE LOOP IMAGERY
avn0IDA-lalo

Elsewhere, INVEST 98L has become a little better looking in satellite imagery today.  A LLC did develop yesterday evening, and albeit not well defined on satellite loop imagery, it is in close proximity to the convection to the east.  This area of disturbed weather is located approximately 425 miles SSW of Bermuda.  Upper level winds are marginal at the moment, at least at the time of analysis, and further development should be slow to occur.  The NHC has designated a MEDIUM (50%) probability of cyclone formation over the next 5 days.  Based on current and forecast steering, this area should continue on a NW motion for the next 2-3 days, before a more northward motion takes place. 

INVEST 98L SATELLITE LOOP IMAGERY
avn098L-lalo

INVEST 98L 12Z DYNAMIC GUIDANCE
98L 12Z DYNAMIC GUIDANCE

During analysis of the global model solutions, it appears this may travel close enough to the U.S., to help trigger a possible coastal development next week, which I will touch on at the end of this synopsis.

INVEST 99L was located SOMEWHERE near the NE tip of the Yucatan Peninsula.  The following information was available from the ATCF FTP product:

8:00 am EDT Sat Sep 26
Location: 19.0°N 88.2°W
Moving: NNE at 5 mph
Min pressure: 1008 mb / 29.77 in
Max sustained: 30 mph

I threw in SOMEWHERE, as based on close analysis of various satellite loop channels, it is extremely difficult to pinpoint any type of circulation center.  However the given location does appear to have a weak circulation present.

INVEST 99L SATELLITE LOOP IMAGERY
avn099L-lalo

rgb099L-lalo

SSEC GEOSTATIONARY VISIBLE SATELLITE LOOP
latest_east_vis_conus

Looking at the current wind shear product, the situation has changed, in that this system is still being blasted by 30-35 knots of SWLY wind shear.  This change is being produced by the ULL that is over Texas, which has dug in a little deeper, and is moving slowly toward the NE in tandem with 99L, keeping shear in place.  NHC has lowered the probability of cyclone formation during the next 5 days to LOW (30%)

The recent wind shear forecast is not as promising as it was 12 hours ago.  So, this INVEST may remain under SW shear for the remainder of the forecast period.  Based on this, I do not foresee any type of significant organization at the moment, unless there is an abrupt change in the shear forecast.  This area could however, bring some significant amounts of rain to coastal areas of the eastern GOMEX over the next 72 hours.

GFS 72 HOUR PRECIPITATION FORECAST
GFS 72 HOUR PRECIP

The INVEST is moving to the north near 10 mph, and I expect this motion through today.  A turn toward the NNE is expected after that, based on analysis of current forecast steering solutions.  This is shown in the 12Z dynamic guidance, to which I prefer the TVCN/TVCC tracks.

ATCF INVEST 99L 12Z DYNAMIC GUIDANCE
99L 12Z DYNAMIC GUIDANCE

I will continue to monitor this INVEST for any significant changes.

As I mentioned previously 98L and 99L may play a role in some type of coastal storm near the end of next week, off the eastern seaboard.  Some of the global models indicate this, with the remnant of 98L being the trigger, with left over energy from 99L.  This in turn supposedly creates a small coastal storm, which phased with a 500 mb trof.

GFS
GFS
ECMWF
ECMWF
CMC
CMC

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
CoCoRAHS OBSERVER  

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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2 Responses to TROPICAL DEPRESSION IDA / INVEST 98L / INVEST 99L FORECAST SYNOPSIS…ISSUED 11:15 A.M. EDT…SEP. 27, 2015

  1. Monty says:

    Thanks Storm. Really watching 99L

  2. dellamom says:

    Thank you, Storm. Extreme southeastern Louisiana is under a tornado warning. Lots of rain around. Fortunately for land interests most lightening is offshore.

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