TROPICAL STORM CHANTAL / POSSIBLE DEVELOPMENT NEAR THE WEEKEND…FORECAST SYNOPSIS…JULY 09, 2013..ISSUED 1:30 P.M. EDT…PHFC

Good afternoon everyone!
I had planned on having this out earlier, however my PC keeps freezing and running slow.

Tropical Storm Chantal has strengthened, albeit you’d never know by satellite imagery.  As of the 11;00 a.m. EDT Advisory from the NHC, the following was available on Chantal: 11:00 AM AST Tue Jul 9
Location: 14.4°N 61.5°W
Moving: WNW at 29 mph
Min pressure: 1006 mb
Max sustained: 60 mph

HURREVAC TROPICAL STORM CHANTAL TRACKING MAP CHANTAL TRACKING

NHC WATCHES AND WARNINGS MAP

NHC LOCAL STATEMENTS
http://www.nhc.noaa.gov/text/index_hls3.shtml

NHC FORECAST INTENSITY

FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 14.4N  61.5W   50 KT  60 MPH
 12H  10/0000Z 15.8N  65.0W   55 KT  65 MPH
 24H  10/1200Z 17.4N  68.5W   60 KT  70 MPH
 36H  11/0000Z 19.3N  71.5W   35 KT  40 MPH...INLAND
 48H  11/1200Z 21.3N  73.6W   35 KT  40 MPH
 72H  12/1200Z 24.5N  76.0W   45 KT  50 MPH
 96H  13/1200Z 26.5N  77.0W   45 KT  50 MPH
120H  14/1200Z 27.5N  78.0W   40 KT  45 MPH

Chantal continues to move very quickly toward the WNW.  I expect this motion to continue for the next 24-36 hours up until she reaches the Island of Hispaniola.  After this time, the western periphery should begin weaken as a break in the ridge is forecast by the steering forecast maps.  This will allow Chantal to take a track into the Bahamas.  As this weakness becomes stronger, steering flow will weaken, and Chantal should slow her forward speed.  Soon thereafter, a ridge builds back in to her NE, and a turn more to the Florida Coast should take place.  Based on the current steering layers map displaying a weakness over the Bahamas, and the current run of the forecast steering layers maps from the PSU e-WALL site, I concur with the current NHC forecast track up to day 4-5, however based on a blend of CMC and GFS track forecast, I prefer in between the NHC Official track, and the TVCC / TVCN consensus.  Based on this, the East Central Florida Coast, to possibly the Georgia border, could come under a Tropical Storm Watch / Warning in a few days.

12Z DYNAMIC MODEL GUIDANCE
12zatcfearlyinvest2bestCHANTAL

Looking at satellite loop imagery, I was rather surprised by Chantal hitting 60 mph.  Her signature is fairly ragged, however information passed about radar signature seems to indicate she has a tightly wound core.

CHANTAL SATELLITE FLOATER LOOP IMAGERY

Chantal is still battling with wind shear out of the NW at about 15-20 knots.  The most recent (I have no idea what is taking the update so long) Zonal Shear forecast map from the GFS does indicate Chantal may fall under the Zero zonal shear value sometime later this afternoon, so some further slow strengthening could occur over the next 24 hours, albeit her fast forward speed could become a hindrance.

CURRENT WIND SHEAR MAP FROM CIMSS

GFS ZONAL SHEAR FORECAST



Based on the current forecast track, in which most Dynamic Models and Ensembles are pretty much in agreement with, as Chantal feels the weakness in the ridge, she should slow her forward speed over the Bahamas.  The NHC indicates a weakening, however, I have to agree with one of my colleagues, meteorologist Bob Acanfrio, that Chantal will need to be monitored closely, as if she hangs around the area long enough and she is slow enough, the zonal shear indicates a substantial weakening in shear values, which could possibly allow her to try and build an upper level anticyclone, albeit brief in nature.

I will continue to monitor Chantal closely, and will try to have an earlier update tonight, provided my PC agrees with me.

Elsewhere, the GFS is still persistent in developing another Tropical Storm in the EATL/CATL in about 4 days from now.  Again, the entity that may be the trigger is just off the West African Coast.  Albeit none of the other models, especially the ECMWF (The EURO hasn’t even initialized Chantal yet), I will not rule this out right now, as according to the current wind shear forecast, this should have upper air support as it crosses the Atlantic.

GFS MODEL FORECAST
06zgfs500mbHGHTPMSLtropical060

06zgfs500mbHGHTPMSLtropical168

EUMETSAT SATELLITE IMAGERY

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 CHANTAL / POSSIBLE DEVELOPMENT NEAR THE WEEKEND…FORECAST SYNOPSIS…JULY 09, 2013..ISSUED 1:30 P.M. EDT…PHFC

  1. TexasHurricane says:

    Thanks storm…

  2. teammc01 says:

    Thank you, StormW

  3. Monty says:

    Thanks Storm. Do you think Chantal will stay together long enough to make it into the GOMEX…should it track that way?

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