TROPICAL DISTURBANCE INVEST 99L FORECAST SYNOPSIS…ISSUED AUG. 31, 2014…9:25 A.M. EDT…WEST CENTRAL FLORIDA HURRICANE AND SEVERE WEATHER FORECAST CENTER

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Good morning everyone!

Tropical Disturbance INVEST 99L remains disorganized this morning.  Based on the 06Z ATCF tracking update, the following information was available regarding INVEST 99L:

LOCATED: 17.6N…87.1 W
MOTION: WNW 12 MPH
MAX SUSTAINED: 30 MPH
PRESSURE: 1009 MB / 29.80 IN.

INVEST 99L FLOATER SATELLITE LOOPS

WATL SATELLITE LOOPS

Albeit this system is currently disorganized, the lower level circulation is a little easier to define in satellite loop imagery.

Based on analysis of the current wind shear product from CIMSS, INVEST 99L has been  under about 20 knots of northerly wind shear.  However, the disturbance is now moving into an area where shear has been on the decrease over the past 24 hours.

CIMSS WIND SHEAR MAP

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CIMSS 24 HOUR SHEAR TENDENCY

The most current wind shear forecast indicates zonal shear will begin to subside today as this disturbance begins to cross into the Yucatan Peninsula. Upper level winds are forecast to become more conducive for further development in about 12 hours.  Based on this analysis, some better organization should begin once 99L enters the BOC / SW GOMEX.  Once in the SW GOMEX, this system will have to be monitored closely.

Based mainly off analysis of current steering, INVEST 99L continues toward the WNW.  This motion is also noted in satellite loop imagery, although given the ambiguity near and around the “center”, satellite imagery may indicate just a slight more westward component.

CURRENT STEERING LAYER MEAN

The NHC has designated a MEDIUM (50%) probability of tropical cyclone formation with INVEST 99L during the next 5 days.

NHC GRAPHICAL 5 DAY TROPICAL WEATHER OUTLOOK

Based on analysis of the steering layers forecast maps from the PSU e-WALL tropical site, valid for 12Z today, I expect the WNW motion to continue today, with a slight bend toward the left as the disturbance enters the BOC, due to ridging being reinforced to the north over the Gulf coast states area at the moment.  For the most part, this should continue into Mexico as forecast.  However, in past experience as a forecaster, systems that enter into the BOC need to be monitored carefully, as in my past experience with these BOC systems, as the disturbance crosses the Yucatan Peninsula, the low level circulation will become somewhat disrupted, and as it enters the BOC, a center relocation/reformation will most likely occur.  Some of these systems in the past, have had center re-locations further north.  Generally, a center reformation will occur under where the heaviest convection develops.  The reason I say it will need to be monitored closely for this is, should the center relocate too far north, it could pickup the steering flow that is shown in the blue arrows, vice the flow it is in right now, shown by the pink arrows.

FORECAST STEERING
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Unfortunately, Dynamic Model guidance is scant at the moment.

12Z DYNAMIC MODEL TRACK GUIDANCE
99L DYNAMIC TREND

The second thing which needs to be monitored is, if the upper level winds are favorable, systems this time of year have a tendency to ramp up a little quicker in the BOC, due to the shape of the coastal land mass.  As air flows counter-clockwise around the disturbance, this area helps force air toward the center of the system…what we call forced convergence.  This aids in a steadier ramp up of these type of systems.

I will continue to monitor this area closely over the next 72 hours for any significant changes and may post an update sometime this afternoon.

Elsewhere, the area in the CATL I have been monitoring has lost much of its structure.  The culprit…DRY AIR!

CATL SATELLITE LOOP

Currently, upper level winds are conducive for development, and are forecast to remain conducive during the next 24 – 30 hours, when thereafter, this area will encounter some strong westerly shear.

I will continue to monitor this area, however development doesn’t seem likely at the moment, given the wind shear forecast.  In fact, anything coming off the coast of Africa over the next 5 – 7 days is going to have to remain at, or just below 10 degrees latitude to avoid wind shear.

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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
OFFICIAL SKYWARN SPOTTER (ADVANCED)

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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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15 Responses to TROPICAL DISTURBANCE INVEST 99L FORECAST SYNOPSIS…ISSUED AUG. 31, 2014…9:25 A.M. EDT…WEST CENTRAL FLORIDA HURRICANE AND SEVERE WEATHER FORECAST CENTER

  1. Monty says:

    Hmmm…looks like we have TD5…for a day or so anyways.

  2. originallt says:

    Morning Storm, Looks like 99L is trying to organize right over the Yucatan Peninsula itself!

  3. Greg Goodman says:

    Thanks for the update mr storm Rest tomorrow mr storm I am tomorrow is my birthday I turn 50.

  4. TexasHurricane says:

    I would say we are in those “blue arrows”….will keep an eye out just in case. Thanks Storm!

    • Monty says:

      Parents live in IAH TexasHurricane. I’m still trying to get back to either IAH or SAT.

      • TexasHurricane says:

        I know I will probably feel stupid after you answer this but what does IAH and SAT stand for? Since you responded to me and i live in TX, I assume the SAT stands for San Antonio Texas?

        • Monty says:

          Don’t feel stupid TexasHurricane. Storm dictates no stupid questions on this blog…believe me…I’ve asked my fair share. Regarding your question…not many people keep up with this…me being with aviation and Storm/Elliott being both Marine and Aviation…these are simply City Codes. Yes…you pegged it…SAT is San Antonio…IAH is Intercontinental Airport…Houston. Nice call Sir. A pleasure knowing you TexasHurricane!!

          • TexasHurricane says:

            Oh ok, I see. Houston is 2 hours from us. We are close to LA border. Hope you are able to get to where you want to go. By the way…I am not a Sir….lol 🙂

            • Monty says:

              I have friends/relatives stretching from MAF (Midland, TX) to MSY (New Orleans). I grew up in SAT…sure did love it!! You’re more of a Sir than you think TexasHurricane. 🙂

  5. Monty says:

    Thanks Storm. Another weird season…curious to see if BOC system heads further North. As you have predicted…dry air kicking everything’s butt in the Atlantic. There have been quite a few impressive systems…at least at the start.

  6. originallt says:

    Thanks, Storm. Have a great rest of the Holiday weekend!

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