TROPICAL STORM GABRIELLE / INVEST 99L / INVEST 98L FORECAST SYNOPSIS…SEP. 05, 2013…ISSUED 10:20 A.M. EDT…PHFC

Full plate today…Good day to everyone!

Tropical Depression SEVEN was upgraded to Tropical Storm GABRIELLE yesterday evening by the NHC.  As of the 8:00 a.m. EDT Intermediate advisory from the NHC, the following information was available, and is posted on the Global Tracks map:

NHC GRAPHICAL TROPICAL WEATHER OUTLOOK (CLICK MAP FOR FULL OUTLOOK)

GLOBAL TRACKS 7 TROPICAL STORM GABRIELLE FORECAST TRACK
GABRIELLE

GABRIELLE FORECAST ERROR CONE
GABRIELLE ERROR

NHC WATCH / WARNING MAP (CLICK ON MAP FOR HURRICANE LOCAL STATEMENTS)


The latest motion reported was to the NW, which would tend to make sense, albeit a slight shift to WNW is plausible, based on analysis of the current low level steering mean.

700 – 850 MB STEERING LAYER

Analysis of IR2 Shortwave satellite loop imagery, indicates GABRIELLE may have become almost stationary again, and indications of a possible center reformation to the east, or SE of Puerto Rico may be occurring.

GABRIELLE SATELLITE LOOP IMAGERY

NWS DOPPLER RADAR LOOP SAN JUAN
http://radar.weather.gov/radar.php?rid=JUA&product=N0Z&overlay=11101111&loop=yes

Based on this, combined with the forecast steering layers maps run, valid for 12Z, the forecast track for GABRIELLE may not be concrete at the moment.  Should a center reformation occur in the areas mentioned, model guidance for one, would have to shift back to the right, and depending on how far the center may possibly reform, could change the guidance track, especially if Gabrielle slows or even stalls for a time.  Albeit this could occur, I prefer the overall look of the track, with the exception of a possible more WNW track for a brief period, bringing GABRIELLE closer to the SE Bahamas, before the approaching trof has a greater affect on her.  Even with this current uncertainty, satellite imagery indicates the trof is approaching at a decent pace, and appears to have deepened somewhat.  Based on this, I don’t feel at the moment there will be too much deviation from the possible track I just mentioned.  However, let’s see what happens over the next few hours, and what consecutive guidance runs indicate.

12Z DYNAMIC MODEL GUIDANCE
12zatcfearlyinvest2bestGABRIELLE

WATER VAPOR LOOP SHOWING APPROACHING TROF

Based on either scenario, the current wind shear forecast shows upper level winds to become more favorable over the next 12-18 hours, and remain somewhat favorable through 42-48 hours.  If GABRIELLE takes the forecast track, she will encounter some shear not too long after.

I will continue to monitor GABRIELLE for any significant changes throughout the day.

Residents in the SE Bahamas should monitor the progress of this system for any significant changes.

The  trof of low pressure in the BOC has been designated INVEST 99L.  Satellite loop imagery indicates this area may be trying to consolidate a Low Level Circulation (LLC) albeit weak at the moment.  An increase and consolidation of convection is also noted.

INVEST 99L SATELLITE LOOP IMAGE

This trof is moving toward the west, and I expect this motion to continue for the next 48 hours.  Based on the current wind shear map from CIMSS, upper level winds are marginal for development, but are forecast to become conducive during the next 24-36 hours.

Based on this, 99L may become better organized, and I won’t rule out the probability of seeing a depression prior to landfall in Mexico.

I will continue to monitor this area throughout the day for any significant changes.

The Tropical Wave in the CATL has been designated INVEST 98L.  Albeit there seems to be a slight organization, dry air will most likely inhibit any quick development of this.  Upper level winds are marginal at the moment, and based on a possible WNW to NW track, wind shear will increase in about 60-72 hours.

INVEST 98L SATELLITE LOOP IMAGE

I will continue to monitor this wave over the next 72 hours for any significant changes.

The area of disturbed weather NE of GABRIELLE, which was circled earlier in the NHC Tropical Weather outlook appears to have been pretty much absorbed by Gabrielle.

Tropical Storm formation is not expected during the next 48 hours.

Have a blessed day!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST
MEMBER WEST CENTRAL FL AMS 
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced)
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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5 Responses to TROPICAL STORM GABRIELLE / INVEST 99L / INVEST 98L FORECAST SYNOPSIS…SEP. 05, 2013…ISSUED 10:20 A.M. EDT…PHFC

  1. TexasHurricane says:

    So what happened to storm getting pulled north? Guess the storms in the BOC don’t do that…..Go figure….

  2. Monty says:

    Thanks Storm…echoing Dellamom. I guess an AF Reserve Hurricane Hunter Aircraft found TD Gabrielle all messed up. Let the wackadoo season continue.

  3. dellamom says:

    But, um, well, wasn’t this season supposed to be over?! Seriously, I am so glad those idiots are not on this site. Of course, if they were, they’d know what Storm has to say and they’d know what to expect. Thanks Storm for keeping it real for us and for the hard work you are facing now. God Bless You Storm. Prayers to all in Gabrielle’s path. Even a little bad weather is not good when it follows other bad weather.

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