TROPICAL CYCLONE FORMATION: INVEST 99L: MEDIUM (60%)
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(T. F. “Storm” Walsh III)
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CURRENT 2016 ATLANTIC TROPICAL CYCLONE TOTALS:
TOTAL STORMS: 14
MAJOR HURRICANES: 3
StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 13-15
INTENSE HURRICANES: 3-4
Good day everyone!
The area of cloudiness and showers over the northern Bahamas, which is associated with a broad surface low, has not changed much since yesterday. The NHC states that upper level winds could become a little more conducive by Wednesday, and have now designated a MEDIUM (60%) probability of development during the next 5 days.
At the time of analysis, the area of disturbed weather was designated INVEST 99L at 2:00 p.m. EDT. The following information was available on INVEST 99L in the ATCF BTK 18Z product:
2:00 PM EDT Mon Oct 17
Location: 22.0°N 72.5°W
Moving: ESE at 10 mph
Min pressure: 1008 mb / 29.76 in
Max sustained: 30 mph
The 12 hour averaged motion yielded a 10 mph ESE direction.
Based on analysis of satellite loop imagery, the broad surface circulation has shown better definition. Analysis of the 850 mb vorticity product from CIMSS indicated vorticity has increased at the 850 mb level. Vorticity at the 925 mb level is still somewhat weak.
Based on my analysis of the current wind shear forecast from the GFS model, the forecast is now showing upper level winds may begin to become more conducive for slow development by possibly Wed. evening, and become a little more favorable by Friday morning, with the sheared flow reversing to a small upper level anticyclone over the path the models indicate at the moment, albeit not optimal as far as upper level winds for significant development. 99L at the moment, is under some 40-50 kts of westerly shear.
Based on analysis of the GFS and ECMWF MSLP Normalized Anomaly maps, both are in good agreement of 99L continuing more toward the east, then beginning slow development. The models then begin to move it N to NNW, and still insist on the system phasing with the approaching 500 mb trof. This could start out as tropical in nature, however looking at the forecast upper pattern, I’m leaning toward sub-tropical at the moment. If it phases with the 500 mb trof later on, it would become an extra-tropical feature (more of a baroclinic feature).
Based on the current GFS solution, some effects may be felt along the Tidewater area, with the brunt over New England and NE U.S. area. The ECMWF takes the system away from the U.S. At the moment, forecast track based on the global pressure models should be considered preliminary until a definitive system becomes established.
I will continue to monitor this situation, but will not have another update until sometime on Wed.
Elsewhere, the disturbed weather I ave been monitoring in the extreme SW Caribbean Sea has diminished. However, some convective activity remains over the area, and upper level winds are slightly conducive for development, should activity show an increase. The GFS wind shear forecast indicates upper level winds may remain conducive over the area for the next 4-5 days. I am going to monitor the area, for any significant changes.
Elsewhere, Tropical Storm formation is not expected during the next 7-10 days.
Have a blessed evening!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS