TROPICAL DISTURBANCE INVEST 99L…SPECIAL FORECAST SYNOPSIS…ISSUED AUG. 27, 2016…7:20 P.M. EDT

TROPICAL CYCLONE FORMATION: INVEST 99L (40%) / T.S. GASTON / 91L (30%)

Disclaimer:  This site is not affiliated with the National Hurricane Center, Storm Prediction Center, or National Weather Service.  ALL forecasts herein are the result of my analysis, and I am solely responsible for the content.
(T. F. “Storm” Walsh III)

For those who have donated to my site, your help has been greatly appreciated.  For those not aware, donations to my site help me offset my personal out of pocket expenses…such as some of the model maps you view on here, are only available due to my subscription to the corresponding site.  The F5 Data maps I post, also another out of pocket expense (monthly subscription).  Updates to software (weather related), and costs for my domain name are also out of pocket to me.  To donate, please click the DONATE button to the right.  Any help you provide is immensely appreciated!  Although it may seem I am not here and working in support of your donation, I have to work my forecasting time around my ever changing work schedule.

CURRENT 2016 ATLANTIC TROPICAL CYCLONE TOTALS:

TOTAL STORMS: 7
HURRICANES: 3
INTENSE HURRICANES: 0
U.S.LANDFALLS: 2

StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 13-15
HURRICANES: 6-7
INTENSE HURRICANES: 3-4

Good evening everyone!

Tropical disturbance INVEST 99L continues to move slowly through the southern Bahamas..Based on the ATCF BTK information, the disturbance may be moving slightly north of due west.  However the bulk of the system may be moving to the WNW.  As of the 18Z ATCF BTK update, the following was available on INVEST 99L:

2:00 PM AST Sat Aug 27
Location: 23.4°N 78.7°W
Moving: WNW 10mph
Min pressure: 1009 mb / 29.80 in
Max sustained: 30 mph

NHC 5 DAY TROPICAL OUTLOOK (LINKED)
two_atl_5d0

Recent satellite loop imagery indicates a still disorganized system.  Although the last few frames indicated the mid level circulation may be consolidating.  I have spent a good amount of time following the IR2 floater channel, which acts as night time visible.  I did notice the surface center earlier at around 1400Z in the loop imagery, however it has since become discernible.  It is unknown whether it is now obscured by cloud cover, or if the mid level rotation may be becoming the more dominant center, which may be almost caught up to the lower level circulation.  In any case, there appears to be some slight fanning out of the cloud cover, and the upper level wind pattern has improved slightly over the past 6 hours.

INVEST 99L SATELLITE LOOP IMAGES FROM NOAA AND RAMSDIS
avn0-lalo99L

tropical_ge_4km_visir2_floater_2.99L

Wind shear has fluctuated today, and is currently stronger than earlier today.  This is due to an upper level low to the north of the INVEST, which was fairly strong earlier.  The combination of the flow around this upper low, and the ridge over the Yucatan peninsula tip, is providing 20-25 knots of NW shear over a small portion of INVEST 99L.  However, going back in time in the images, the upper low has weakened substantially.  This could lead to wind shear relaxing once again.

RECENT WIND SHEAR PRODUCT FROM CIMSS
wg8shr

In fact, this is what the most recent wind shear forecast indicates.  IF the shear forecast is correct, 6 global models from the NOAA RUC HFIP diagnostic site, ALL relax shear to favorable levels within the next 24- hours.  Analysis of the GFS and ECMWF deep layer shear forecast indicates this as well, with both the GFS and ECMWF in almost remarkable agreement of re-establishing an upper level anticyclone over 99L, after it passes through the FL. Straits.  Both models are in agreement of the upper level anticyclone developing just south of the FL. keys, to just WSW of the Keys, in approximately 24-36 hours, and pretty much maintaining this feature in the path projected, whether you’re looking at the GFS track, or ECMWF track.

GFS WIND SHEAR FORECAST (note upper level anticyclone west of FL. Keys)
gfs_dl_shear_gulf_5

Based on this, I do believe we should still begin to see better development of this system, once it enters the GOMEX south or WSW of the Florida Keys.  Depending exactly on upper level conditions, and exact track, 99L may have the potential to attain hurricane strength in approximately 4 – 5 days.  IF the favorable conditions do pan out…I cannot rule this out at the moment.

INVEST 99L continues W to WNW, and I expect this motion to continue during the next 48 hours, with a possible northward turn shortly thereafter.  Based on the updated forecast steering layers maps, this seems plausible, and may be inline with the 18Z Dynamic model guidance.  However, I must reiterate, track guidance is still not to be considered to reliable at the moment, until IF and WHEN 99L becomes better organized with a solid closed low level circulation to track.  I believe the guidance at the moment may be working off the overall system.  Forecast steering indicates that a portion of the ridge over the NE United States may begin to weaken, and retrograde toward the west closer to the central portion of the U.S.  In addition, it appears as if INVEST 91L currently near Bermuda, may impart a weakness just to the NE  of the Florida peninsula by 48-72 hours.  Models vary on strength and track with this, with the ECMWF being a little more centered in the GOMEX, then curving it toward the FL. Panhandle as a 90-95 kt hurricane, with other models remaining closer to FL with a weaker system.  The CMC GGEM indicates a CAT 1 in the eastern FL. panhandle near 82-83W, and GFS further east toward the Big Bend area with a Tropical Depression.  Latest ECMWF EPS members are in between these scenarios, from the extreme western tip of the FL. Panhandle, to the Big Bend area.

At the moment, I know EVERYONE will want to ask where is it going to go, and should I prepare.  I am not going to lie or hype this, and the BEST thing I can tell you right now is, I CANNOT tell you for sure, exactly where this is going over the next 24-48 hours.  Again, steering on this should be considered preliminary until IF and WHEN it becomes developed.  As we have seen in the past 3-4 days, the modeling has shifted pretty much from TX, to FL, to LA, to FL., to MS, to FL. (get my drift).  So, I caution you, everybody and their brother is going to try their hand at telling you they know where it will go and it’s going to be speculation at best.  It is recommended that residents from AL. to the Tampa Bay area closely monitor this system, until I can get a better handle on it if and when development takes place.  For right now, I have to side with the 18Z Dynamic guidance consensus models TVCC / TVCN, however a blend of these and the ECMWF solution may be in order.

ATCF 99L 18Z DYNAMIC GUIDANCE
99L 18Z DYNAMIC GUIDANCE

ECMWF 168 HOURS
ECMWF.99L

Regardless, residents of the Bahamas and the Florida Peninsula, especially areas of S. Florida and central Florida should be prepared for some heavy rainfall over the next few days, which could cause flooding on lower areas, and some Urban flooding.  From the NHC in Miami:

Gusty winds and locally heavy rainfall are likely over portions of the Bahamas, and will spread into parts of southern Florida and the Florida Keys by Sunday. Interests elsewhere in Florida and the eastern Gulf of Mexico should continue to monitor the progress of this disturbance.

I don’t have time this evening to spend on 91L, but will try and touch on it tomorrow.  Another wave is expected to exit Africa around Tues, and definitely may bear watching.

I do intend on having an update probably closer to early evening tomorrow.

Have a blessed evening!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER

Advertisements

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.
Image | This entry was posted in Tropical Synopsis. Bookmark the permalink.

7 Responses to TROPICAL DISTURBANCE INVEST 99L…SPECIAL FORECAST SYNOPSIS…ISSUED AUG. 27, 2016…7:20 P.M. EDT

  1. Monty says:

    Thanks Storm. All eyes on 99L.

  2. dellamom says:

    Thank you, Storm.

  3. Donna McClain says:

    Thank you!

  4. CHARLES O says:

    Thank you Storm . Been following you since be fore Ike ! Going with your forecasting of Ike is what had me more prepared for the eventual track than many others who were certain that Ike was a Fla event . Your insight is always appreciated .

  5. Bob says:

    Excellent analysis, as usual Storm. Thank you.

    Bob

  6. Mike Doll says:

    Thanks Storm. Tested the generator today and getting fuel
    Tomorrow.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s