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(T. F. “Storm” Walsh III)
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Good day everyone!
Just for a refresher, based on analysis of various parameters of climate models for the previous month, and based on the closest analog years matching the parameters, my forecast for this hurricane season is as follows. However, if conditions become forecast to improve over the summer months, I ma have to make a slight increase in these totals. Please note, the following totals DO NOT include T.S. Arlene from April.
TOTAL STORMS: 12-15
MAJ. HURRICANES: 3-4
The NHC has designated a HIGH (90%) probability of cyclone formation for INVEST 93L, and a MEDIUM (60%) probability of cyclone formation for INVEST 92L, during the next 5 days.
URGENT UPDATE: NHC issues advisory number ONE on potential Tropical Cyclone in the Atlantic. TROPICAL STORM WARNING ISSUED:
WTNT32 KNHC 182055
Potential Tropical Cyclone Two Advisory Number 1
NWS National Hurricane Center Miami FL AL022017
500 PM AST Sun Jun 18 2017
…TROPICAL STORM WARNING ISSUED FOR PORTIONS OF THE WINDWARD
SUMMARY OF 500 PM AST…2100 UTC…INFORMATION
ABOUT 815 MI…1310 KM ESE OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS…35 MPH…55 KM/H
PRESENT MOVEMENT…W OR 280 DEGREES AT 23 MPH…37 KM/H
MINIMUM CENTRAL PRESSURE…1008 MB…29.77 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The government of Barbados has issued a Tropical Storm Warning for
Barbados, St. Vincent, and the Grenadines.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for…
* St. Vincent and the Grenadines
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.
For storm information specific to your area, please monitor
products issued by your national meteorological service.
DISCUSSION AND 48-HOUR OUTLOOK
At 500 PM AST (2100 UTC), the disturbance was centered near latitude
7.5 North, longitude 50.4 West. The system is moving toward the
west near 23 mph (37 km/h). A fast motion toward the west-
northwest is expected to continue for the next 48 hours. On the
forecast track, the disturbance is expected to move through the
Windward Islands Monday night and Tuesday.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Some strengthening is forecast during the next 48 hours, and the
disturbance is expected to reach tropical storm intensity on Monday
before it reaches the Windward Islands.
Shower and thunderstorm activity associated with the disturbance
has become better organized since yesterday, and some additional
development is possible during the next couple of days before
conditions become less favorable for tropical cyclone formation
over the Caribbean Sea.
* Formation chance through 48 hours…high…70 percent
* Formation chance through 5 days…high…70 percent
The estimated minimum central pressure is 1008 mb (29.77 inches).
HAZARDS AFFECTING LAND
WIND: Tropical storm conditions are expected to first reach the
warning area overnight Monday and Tuesday morning, making outside
preparations difficult or dangerous.
RAINFALL: The disturbance is expected to produce total rain
accumulations of 2 to 4 inches over the Windward Islands Monday
Next intermediate advisory at 800 PM AST.
Next complete advisory at 1100 PM AST.
SPECIAL UPDATE FROM THE NHC…RECEIVED 4:30 P.M. EDT
NHC will be initiating advisories at 5 PM AST on Potential Tropical Cyclone Two, located east-southeast of the Windward Islands.
We’ll begin closer to home first.
INVEST 93L is an area of low pressure located or centered over the extreme Western portion of the Gulf of Honduras.
As of the 18Z ATCF BTK report, the following was available on INVEST 93L:
MAX SUSTAINED WIND: 40 mph
PRESSURE: 1006 mb / 29.71″
MOVEMENT: NW 4 mph
Analysis of satellite loop imagery indicates convection has increased over the past few hours, mainly east of the center, and has become better organized. However, based on my analysis of various satellite loop images, especially Shortwave IR channel IR2, the 18Z location may be a little inaccurate, as where the last position was was indicated, was just east of the Yucatan peninsula. That low appears to be over the peninsula at this time, and convection free. The convection and circulation to the east, appears as it may be mid level, however it is the more dominant feature. Usually when this occurs, chances are sometimes, that the Low Level Circulation will relocate, or regenerate under the convective swirl. This isn’t always the case, but I would not be surprised to see NHC relocate the center further east over the next 24 hours. Should this occur, it would have an impact on future track.
Based on the information contained in the ATCF BTK report above, should this become organized enough to be named, it would probably go straight to a T.S. or STS status, as the sustained winds are at 40 mph. This of course, is dependent upon whether or not it can sustain current conditions, and / or if the center relocates.
Based on my analysis of the current and forecast wind shear products, upper level winds have improved over the area, albeit not particularly optimal as convection is still being blown to the east. The wind shear forecast calls for a somewhat elongated upper level anticyclone to become further developed, and remain with the disturbance during the next 72 hours. Based on this, and current forecast track thinking, I cannot rule out the development of a tropical or sub-tropical storm within the next 36 – 48 hours. Some of the intensity guidance models indicate this, however the more accurate of the models only bring this to depression status.
CURRENT WIND SHEAR FROM CIMSS FOR 93L
GFS WIND SHEAR FORECAST
Based on analysis of the latest global models runs, ensemble runs, and current and forecast steering maps, I expect the disturbance to continue slowly toward the NW over the next 48 hours. After this system enters the GOMEX, forecast track is still somewhat up in the air, as there s still some discrepancies in the global models, albeit over all track has shifted more toward the west, and not over the Florida Panhandle. Based on a blend of the ECMWF EPS and ECMWF, CMC GGEM, and GFS Ensemble, and GFS models, and recent dynamic model track guidance (TVCN), given the large discrepancy in track, all I can go with at the moment is, residents from Mississippi to Texas should monitor the progress of this system. Not that I expect strong winds from this right now, but the fact it’s east weighted and will provided heavy rainfall. For now, I am expecting heavy rain over portions of Central America, the Yucatan Peninsula, Jamaica, the Cayman Islands, and western Cuba during the next few days.
INVEST 93L ATCF 18Z DYNAMIC GUIDANCE
Once again, as soon as we see what happens to the low level circulation, and once this becomes much better organized, guidance models should have a better handle on track. Again, since this won’t be close to the U.S. for another probably 60-72 hours. I work Wed., and have a pressing engagement right after, so IF this disturbance is still over water, I will try to have an update very late Thu. evening.
Elsewhere, the tropical wave INVEST 92L continues to move toward the west at a decent clip. As of the 18Z ATCF BTK report, the following was available on INVEST 92L:
MAX SUSTAINED WIND: 35 mph
PRESSURE: 1008 mb / 29.77″
MOVEMENT: W 20 mph
Analysis of satellite loop imagery this evening indicates INVEST 92L appears to be somewhat better organized than earlier today. Based on analysis of the current wind shear map from CIMSS, upper level winds seem to be gradually improving, with a hint that an upper level anticyclone is trying to develop. The current wind shear forecast from the GFS models indicates upper level wind should continue to become more favorable in about 24 hours, with a small upper level anticyclone, and remaining favorable through 42 hours. Thereafter, as the system enters the eastern Caribbean Sea, upper level winds are forecast to be unfavorable for further development, as wind shear increases. Based on this analysis, I expect some further slow development during the next 24-36 hours, and a tropical depression could form, prior to the onset of wind shear. Based on the quick forward motion, my thinking at the moment is this attaining T.S. status may be low, BUT, we’ll see what happens.
CURRENT WIND SHEAR FOR 92L FROM CIMSS
GFS WIND SHEAR FORECAST (ATLANTIC)
Analysis of current and forecast steering layers maps indicates this disturbance should continue to move in a general W to WNW direction, and enter the eastern Caribbean in about 48 hours Based on the ECMWF EPS forecast, and 18Z model guidance from the ATCF, I prefer the TVCA consensus model track. Regardless of development, I am expecting heavy rain over portions of the Windward Islands Monday night and
Tuesday. Residents of the Windward islands should continue to monitor the progress of this system.
Elsewhere, Tropical Storm formation is not expected during the next 7-10 days.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS