TROPICAL STORM CHANTAL FORECAST SYNOPSIS…JULY 08, 2013…ISSUED 11:30 A.M. EDT…PHFC

I wanted to post this..it just came out from Dr. Masters at WU, referencing Dr. Klotzbach and Gray from Colorado State:

A statement from Dr. Masters this morning —

“Chantal’s formation on July 8 is an usually early date for formation of the season’s third storm, which usually occurs on August 13. A large number of early-season named storms is not necessarily a harbinger of an active season, unless one or more of these storms form in the deep tropics, south of 23.5°N. According to Phil Klotzbach and Bill Gray, leaders of Colorado State’s seasonal hurricane forecasting team,

“Most years do not have named storm formations in June and July in the tropical Atlantic (south of 23.5°N); however, if tropical formations do occur, it indicates that a very active hurricane season is likely. For example, the seven years with the most named storm days in the deep tropics in June and July (since 1949) are 1966, 1969, 1995, 1996, 1998, 2005, and 2008. All seven of these seasons were very active. When storms form in the deep tropics in the early part of the hurricane season, it indicates that conditions are already very favorable for TC development. In general, the start of the hurricane season is restricted by thermodynamics (warm SSTs, unstable lapse rates), and therefore deep tropical activity early in the hurricane season implies that the thermodynamics are already quite favorable for tropical cyclone (TC) development.”

Two of this season’s three storms have formed in the deep tropics–Tropical Storm Barry, which formed in the Gulf of Mexico’s Bay of Campeche at a latitude of 19.6°N, and now Tropical Storm Chantal, which formed at a latitude of 9.8°N. With recent runs of the GFS model predicting formation of yet another tropical storm southwest of the Cape Verde Islands early next week, it appears that the Atlantic is primed for an active hurricane season in 2013.”

Good day everyone!

This forecast is based on information from the 11:00 a.m. EDT Advisory, and the last updates received from model data.

At 11:00 p.m. EDT yesterday evening, INVEST 95L was upgraded to Tropical Storm Chantal.  As of the 11:00 a.m. EDT Advisory from the NHC, the following information was available on Chantal:
11:00 AM AST Mon Jul 8
Location: 10.9°N 51.7°W
Moving: WNW at 25 mph
Min pressure: 1005 mb / 29.68 in
Max sustained: 45 mph

NHC GRAPHICAL TROPICAL WEATHER OUTLOOK

NHC WATCHES AND WARNINGS


TROPICAL STORM CHANTAL SATELLITE LOOP IMAGERY

CARIBBEAN SATELLITE LOOP IMAGERY

As stated in the NHC Forecast Discussion, the motion of Chantal is to the WNW at 25 mph.  I expect this motion to continue for the next 12-18 hours, before a more prominent turn to the WNW takes place (285-290).  Analysis of current and forecast steering layers maps indicates this motion.  However, after careful analysis and consideration of current satellite loop imagery of various channels, combined with the steering forecast analysis, I do concur with the current NHC forecast track, however I am initially to the left for the next 12-24 hours, and just left of the TVCC / TVCN model consensus.  I do however agree with the overall track based on forecast steering, as a weakness in the subtropical ridge occurs within the next 48-60 hours off the SEUS coast.  This should draw Chantal, or what’s left of Chantal, on a more NW course in that time, and eventually bend back toward the U.S. coast.   Right now, not expecting anything strong, should she regenerate.  Again, this is based on current forecast parameters information of this morning.

CARIBBEAN DVORAK SATELLITE LOOP

CURRENT STEERING LAYER

12Z DYNAMIC MODEL GUIDANCE
12zatcfearlyinvest2bestCHANTAL

FORECAST STEERING (SHOWING WEAKNESS)
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Maximum sustained winds are 45 mph.  The NHC does indicate some further slow strengthening of Chantal, however based on the current wind shear map from CIMSS, and Zonal Shear forecast from the GFS 06Z run, Chantal may not see any change in strength until about sometime later this afternoon, as upper level winds become a little more conducive for development.  The problem then lies after she enters the Caribbean, where she begins to lose upper air support in about 48 hours.  As you can see by the current shear map, she is beginning to move into an area where shear increases.

CIMSS WIND SHEAR MAP

FORECAST ZONAL SHEAR 48 HOUR MAP
850200ushear8

Another factor that has come into play as I’ve been analyzing and typing…DRY AIR.  Analysis of VIS and RGB loop imagery indicates some slight ingestion of dry air, based on some small outflow boundaries noted in the imagery.  This indicates she may be jut starting to have to battle dry air, or it could be just a “hiccup” for the time being.  Based on these factors, I believe the NHC may come down slightly on their intensity forecast, and if not, I do not foresee an increase in the forecast.

I will continue to monitor Chantal throughout the day, and will have another update sometime this evening.

I will be open to questions after 1:00 p.m. today

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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13 Responses to TROPICAL STORM CHANTAL FORECAST SYNOPSIS…JULY 08, 2013…ISSUED 11:30 A.M. EDT…PHFC

  1. Monty says:

    Thanks Storm. It will be interesting to see what the Air Force Reserve Hurricane Hunter Aircraft finds.

  2. dellamom says:

    Storm, I don’t like the GFS track at all – it affects your area, Greg and Mikes, and mine! Now starts the time when a lot of Gulf area people are glued to your words, my friend. .

  3. TexasHurricane says:

    Thanks Storm….So much for the rain we were suppose to get. Maybe TX can get a good storm come through this year. I don’t mean a major one, just one that would give good rain.

  4. Shaun Boyce says:

    Your site is the best! I especially appreciate the various forecast models. They are very hard to get anywhere else and allow we amateur meteorologists a chance to see what the professional see. Thank you for your hard work.

  5. originallt says:

    Thanks Storm.

  6. Greg goodman says:

    Mr storm do you think if high pressure builds back in could that force it back west across central Florida and into the gulf.

  7. javier valdes says:

    what your thinking on new gfs run ? it dont weaking CHANTAL that much got as strong ts off fl moving tward Central fl

  8. Teresa says:

    Thanks Storm. Our son’s cutter is in the carribean . Mignt be a bumpy ride for them in a couple days!

  9. teammc01 says:

    Thank you, StormW

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