June 03, 2013…BRIEF UPDATE INVEST 91L…EXTREME SOUTHERN GOMEX:
The NHC has recently increased the probability of INVEST 91L becoming a Tropical Cyclone during the next 48 hours to MEDIUM (30%).
Information contained in the NHC Tropical Weather Outlook at 8:00 p.m., and satellite imagery suggests the circulation associated with this low has become slightly better defined.
Current products from the CIMSS site indicate an outflow channel on the northern semi-circle has become well established again.
The latest run of the GFS and CMC wind shear forecast products indicates upper level winds may become more conducive for development of 91L over the next 42-48 hours. Wind shear over the area has been slowly decreasing over the past 24 hours, based on CIMSS Wind Shear tendency information. Should this trend continue, we could see some better, but slow development of 91L. At this time, I cannot speculate as to whether 91L will attain depression status over the next 42 hours, until I see conditions over the area improve more.
Given that 91L is still in a slow development stage, Model Guidance is not really useful, however based on analysis of forecast steering layers maps, a track toward the western Florida Panhandle to the Big Bend area cannot be ruled out right now. Based on what Dynamic Model Guidance we have, I am leaning toward the CMCI track, and left of the GFS Ensemble suite.
18Z DYNAMIC MODEL GUIDANCE (COURTESY AMERICANWX.COM)
GFS ENSEMBLE GUIDANCE
I will have a full update in the a.m.
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Good day everyone!
Yesterday evening, the area of disturbed weather over the Yucatan area was designated as INVEST 91L.
The NHC has designated a 20% (Low) chance of this disturbance becoming a tropical cyclone during the next 48 hours.
Satellite loop imagery this morning shows a very disorganized area of showers and thunderstorms, as the area continues to be under 30 knots of wind shear at the moment.
Analysis of the floater imagery of 91L indicates a very elongated trof of low pressure, and a familiar scenario we’ve seen in the past…multiple vortices. It appears there may be a relocation of the dominant center trying to reform over the Peninsula itself, however a large turning in the cloud shield is centered near 22.7N;90.0W. Convection has increased again east of the Peninsula, just south of Cozumel.
Overall analysis of the current posted location per ATCF and NHC, current and forecast steering layers maps, current and forecast wind shear products, I am providing 2 possible scenarios on this:
1.) Should 91L continue to drift NNW, and the true center is located NNE of the Yucatan Peninsula, forecast steering is now indicating a track more toward the Big Bend area to the Panhandle of Florida in about 48-72 hours as the steering flow changes to the NNE. If this occurs, 91L will not be able to take advantage of more favorable conditions in about 60-72 hours from now, and could very well dissipate. Regardless of development, residents along the west coast of Florida should be prepared to deal with large amounts of rain from this over the next few days when it moves closer to the Florida Peninsula.
2.) Should the center of 91L relocate to over the Yucatan Peninsula and remain at a drift or Quasi Stationary, the current wind shear forecast from both the GFS and CMC indicate an upper level anticyclone to develop, and relaxing wind shear in about 60-84 hours. In fact, the GFS indicates pretty favorable conditions from that point, remaining for about a 4-5 day stretch over the channel and Florida Straits area. If this scenario pans out, 91L would encounter a more favorable environment, and I would expect to see a little better development.
I will continue to monitor 91L throughout the day for any significant changes.
Elsewhere, 2 Tropical Waves are noted in the NHC 06Z Surface Analysis map. The wave furthest east is also noted in Satellite imagery with a cyclonic signature noted.
Tropical Storm formation is not expected through the next 5-7 days.
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)