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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: 0
U.S. LANDFALLS: 2
Good evening all!
The current GTWO from the NHC now designates only a LOW (20%) probability of cyclone formation during the next 5 days for INVEST 99L
INVEST 90L was upgraded to Tropical Storm FRANKLIN yesterday evening. As of the 5:00 p.m. advisory from the NHC, the following was available on FRANKLIN:
4:00 PM CDT Mon Aug 7
Location: 18.6°N 85.9°W
Moving: NW at 13 mph
Min pressure: 998 mb / 29.47 in
Max sustained: 60 mph
HURREVAC NHC FRANKLIN FORECAST MAPS
Satellite loop imagery indicates FRANKLIN continues to become better organized, and is displaying some stronger banding features, and appears to be developing heavier convection around the center, which may be trying to “ring” around the COC. Overshooting tops seem to have increased. ALL of these features indicate, at least to me, that FRANKLIN may be intensifying.
The current wind shear product from CIMSS indicates an upper level anticyclone is trying to develop near the storm. The upper level wind pattern does indicate an outflow pattern around FRANKLIN, with an outflow jet predominately around the NE semi-circle.
CIMSS UPPER LEVEL WINDS
Based on the current wind shear forecast, the upper level anticyclone should become established during the next 8-10 hours, or just prior to FRANKLIN making landfall over the Yucatan Peninsula. Based on this, current SST’s, OHC, and satellite representation, albeit I concur with the NHC intensity forecast, I cannot rule out FRANKLIN attaining Category ONE hurricane status prior to landfall.
WIND SHEAR FORECAST ECMWF AND GFS
NHC INTENSITY GUIDANCE
INIT 07/2100Z 18.6N 85.9W 50 KT 60 MPH
12H 08/0600Z 19.1N 87.6W 60 KT 70 MPH…INLAND
24H 08/1800Z 19.9N 89.9W 40 KT 45 MPH…INLAND
36H 09/0600Z 20.3N 91.9W 50 KT 60 MPH…OVER WATER
48H 09/1800Z 20.5N 94.0W 65 KT 75 MPH…OVER WATER
72H 10/1800Z 20.5N 98.5W 55 KT 65 MPH…INLAND
The current shear forecast indicates the upper level anticyclone to remain established with the storm, when it exits into the BOC. FRANKLIN will weaken as it crosses the Yucatan Peninsula, however once entering the BOC, given the forecast shear pattern, FRANKLIN could once again become a Category ONE hurricane, prior to landfall in Mexico.
The storm continues to move toward the NW, and I expect this NW to WNW motion to continue for the next 24-36 hours. Thereafter, ridging slowly noses west from the eastern GOMEX, and should impart a more WNW to west motion. Based on this analysis, I concur with the NHC forecast track, which is on the northern portion of the guidance envelope. This makes sense, given that the current motion of 310 deg. is being influenced by a weakness in the ridge, over Mexico. This should place landfall between Poza Rica and Jalapa, based on the forecast track and model guidance.
ATCF 18Z DYNAMIC GUIDANCE T.S. FRANKLIN
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Watch is in effect for…
* The coast of Mexico from Chetumal to Punta Allen
A Tropical Storm Warning is in effect for…
* Belize City northward to the border of Mexico
* The coast of Mexico from Chetumal to Campeche
A Tropical Storm Watch is in effect for…
* The coast of Mexico from Campeche to Sabancuy
A Hurricane Watch means that hurricane conditions are possible
within the watch area, in this case within the next 24 hours.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, in this case within
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area.
Interests elsewhere around the Bay of Campeche should monitor the
progress of this system. A Hurricane Watch may be required for a
portion of the southwestern Gulf coast of Mexico this evening.
For storm information specific to your area, please monitor
products issued by your national meteorological service.
DISCUSSION AND 48-HOUR OUTLOOK
At 400 PM CDT (2100 UTC), the center of Tropical Storm Franklin was
located near latitude 18.6 North, longitude 85.9 West. Franklin is
moving toward the northwest near 13 mph (20 km/h), and a
west-northwestward to westward motion is expected over the next 48
hours. On the forecast track, the center will be near the east
coast of the Yucatan Peninsula this evening or tonight. Franklin
is then expected to move across the Yucatan Peninsula on Tuesday,
and into the Bay of Campeche Tuesday evening or Tuesday night.
Maximum sustained winds are near 60 mph (95 km/h) with higher gusts.
Some strengthening is expected before the center reaches the
Yucatan Peninsula, and Franklin could be near hurricane intensity at
landfall on the east coast of the Yucatan Peninsula.
Tropical-storm-force winds extend outward up to 140 miles (220 km)
from the center.
The estimated minimum central pressure is 998 mb (29.47 inches).
HAZARDS AFFECTING LAND
RAINFALL: Rainfall amounts of 3 to 6 inches, with isolated amounts
of around 12 inches, are possible across the Yucatan Peninsula of
Mexico and Belize through Wednesday, with the highest amounts over
the Mexican state of Quintana Roo. These rains could produce
life-threatening flash floods.
WIND: Hurricane conditions are possible in the Hurricane Watch
area by this evening. Tropical storm conditions are expected to
begin in portions of the warning area this afternoon or evening.
Tropical storm conditions are possible in the watch area in Mexico
STORM SURGE: A dangerous storm surge will raise water levels by
as much as 2 to 4 feet above normal tide levels along the immediate
coast near and to the north of where the center makes landfall.
Near the coast, the surge will be accompanied by large and
Residents within the HURRICANE WATCH AREA should be making preparations for possible hurricane conditions, and should monitor their local NWS for further statements.
I will continue to monitor this situation for any significant changes.
Elsewhere, INVEST 99L continues to struggle with dry air. Based on the 18Z ATCF BTK product, the following was available on INVEST 99L:
2:00 PM EDT Mon Aug 7
Location: 15.5°N 45.3°W
Moving: WNW at 13 mph
Min pressure: 1010 mb / 29.83 in
Max sustained: 30 mph
Satellite imagery indicates a disorganized system, and water vapor imagery shows the dry air W and NW of the system.
Based on analysis of the global models, the ECMWF and GFS don’t really do much with INVEST 99L over the next 72-96 hours. Moderate wind shear is expected near the system over those few days. Based on the shear forecast, it appears zonal shear may weaken somewhat near and over the Bahamas. This, along with moderate OHC could be enough to allow 99L, should anything remain, a chance to grow vertically given the somewhat relaxing wind shear. Based on the ECMWF solution, there may be favorable RH values with the system. The ECMWF wants to develop this to a moderate T.S., while the GFS keeps it an open wave. Based on the marginal shear conditions that are forecast, I’m inclined at the moment, to split the difference, in that we COULD possibly see a tropical depression in about 5-7 days in the Bahamas area. I want to see how the wind shear forecast plays out over the next 48 hours, before going with the ECMWF solution, albeit the ECMWF has been decent thus far on formation and consistency during the past week.
ZONAL SHEAR FORECAST
INVEST 99L is currently moving WNW, and I expect this motion to continue for the next 72 -96 hours. Thereafter, a weakness in the ridge develops close to the Eastern Seaboard of the U.S. The GFS keeps an open wave, moving it into south FL., and the ECMWF brings it in close to the SEUS coastal area as a Tropical Storm. Given current strength and forecast conditions over the next 3-4 days, the system should remain a wave, and being weaker, will be steered by the low level steering flow. Based on this analysis, it should be allowed to move west further. Given the history of the ECMWF, I like the forecast track at the moment, however, given that we have a non organized feature, this will change again over the course of the next few days.
I will continue to monitor both features, however my work schedule has changed this week, so I don’t know when my next update will be posted.
Elsewhere…I am not expecting tropical storm development during the next 5-7days.
Have a blessed EVENING!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS