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(T. F. “Storm” Walsh III)
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STORM W’s SEASONAL HURRICANE FORECAST
TOTAL STORMS: 14-16
MAJ. HURRICANES: 3-4
MAJ. HURRICANES: 6
U.S. LANDFALLS: 5
Good evening everyone!
I am posting this update, as I will not be updating Saturday, and this system may make landfall early Sunday morning. I am posting the link for local statements regarding the system, as well as the NWS Hazards and Warnings map, so you may access up to date information on your area. I will most likely be posting on Sunday evening. On a side note, no local statement links are available at this time. The following map will send you to the NHC website, which will contain these links as local statements are issued.
Tropical Disturbance INVEST 90L had become better organized this morning. and is located east of Nicaragua as Tropical Depression 16. As of the 5:00 p.m. EDT advisory from the NHC, the following was available on T.D. 16:
5:00 PM EDT Wed Oct 4
Location: 12.5°N 82.5°W
Moving: NW at 7 mph
Min pressure: 1005 mb / 29.68 in
Max sustained: 35 mph
HURREVAC T.D 16 NHC TRACKING AND WIND RADII MAPS
Based on my analysis of the current wind shear forecast from the GFS model, indications are that upper level winds improve during the next 24 hours, with the development of an upper level anti-cyclone. An upper level anti-cyclone is what evacuates the warm air that comes up through the center of the system, as it exits the top of the system. This is where the strengthening process occurs, as the more air that is evacuated away from the center in the upper atmosphere, the more of a quantity of warm, moist air can be drawn in at the surface.
GFS WIND SHEAR FORECAST (CIRCLED AREA INDICATES UPPER ANTI-CYCLONE)
The depression is currently over an area where SST’s are 31C, or 88 degrees F. Analysis of the current OHC indicates OHC values are extremely high in and north of the area, all the way up to or near the Yucatan Channel.
90L OHC VALUES
Based on the above factors, and depending on proximity to land, I believe Nate should develop within the next 12-18 hours. I feel there could be a good chance for R.I. (Rapid Intensification) once the system reaches the W. Caribbean, and up through the Yucatan Channel. Also based on these factors, IF Nate can avoid more of land, and if the wind shear forecast pans out, I cannot rule out a Category ONE or Category TWO hurricane prior to PROBABLE U.S. landfall. However, I cannot rule out the possibility of a major hurricane at some point in its travel based on the Maximum Potential Hurricane Intensity Modeling. The ECMWF now indicates a possible CAT 2 to low end CAT3 hurricane at landfall over the Florida Panhandle. The GFS indicates a moderate to strong T.S. near New Orleans. While I concur with the NHC intensity forecast at the moment, I feel it may be a little conservative for where the system will be located on Fri.
MAXIMUM POTENTIAL HURRICANE INTENSITY
NHC INTENSITY FORECAST
INIT 04/2100Z 12.5N 82.5W 30 KT 35 MPH
12H 05/0600Z 13.2N 83.1W 40 KT 45 MPH
24H 05/1800Z 14.6N 83.8W 40 KT 45 MPH…INLAND
36H 06/0600Z 16.7N 84.6W 50 KT 60 MPH
48H 06/1800Z 19.5N 85.8W 60 KT 70 MPH
72H 07/1800Z 25.0N 88.0W 75 KT 85 MPH
96H 08/1800Z 30.5N 86.0W 65 KT 75 MPH…INLAND
120H 09/1800Z 35.5N 82.0W 30 KT 35 MPH…POST-TROP/INLAND
Based on motion over the past 12 hours, TD 16 is moving very slowly to the NW. Based on analysis of forecast steering maps, I expect this motion to continue for the next 48 hours, with a turn more toward the north thereafter. There is discrepancy in the global models and track guidance, and this is expected and should be considered preliminary. However, based on analysis of the 18Z dynamic guidance models, there has been a shift to the left in the guidance. As of the 5:00 p.m. updated map, the NHC track has shifted slightly left as well. Based on this, my conclusion is, the Florida Panhandle and/or big bend area may still be in the highest probability, however until things become more clear in forecast steering, and dynamic guidance, residents from LA to the Florida Big Bend area should monitor the progress of this system closley. The NHC has tasked a G4 flight for tomorrow, as well as special soundings for Florida. This should allow for models to correct and come closer together on track guidance.
18Z TRACK GUIDANCE
I will try to have another update late on Sunday.
Elsewhere, I do not expect any Tropical Storm development during the next 7 days.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS