TROPICAL CYCLONE FORMATION: INVEST 99L (50%) / T.S. GASTON / 91L (20%)
Disclaimer: This site is not affiliated with the National Hurricane Center, Storm Prediction Center, or National Weather Service. ALL forecasts herein are the result of my analysis, and I am solely responsible for the content.
(T. F. “Storm” Walsh III)
For those who have donated to my site, your help has been greatly appreciated. For those not aware, donations to my site help me offset my personal out of pocket expenses…such as some of the model maps you view on here, are only available due to my subscription to the corresponding site. The F5 Data maps I post, also another out of pocket expense (monthly subscription). Updates to software (weather related), and costs for my domain name are also out of pocket to me. To donate, please click the DONATE button to the right. Any help you provide is immensely appreciated! Although it may seem I am not here and working in support of your donation, I have to work my forecasting time around my ever changing work schedule.
CURRENT 2016 ATLANTIC TROPICAL CYCLONE TOTALS:
TOTAL STORMS: 7
INTENSE HURRICANES: 0
StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 13-15
INTENSE HURRICANES: 3-4
Good evening everyone!
I just wanted to give a quick shout out on INVEST 99L, so everyone wouldn’t be hanging, because I believe the last time I updated, we were looking at a hurricane in the GOMEX this coming week.
I already went over how quickly conditions can and do change in the tropics.
For the previous 3-4 days, everything I had analyzed pointed to development by now, which was pretty much backed up by the NHC with them holding it at a high probability for those few days (we both analyze the same stuff, except they have more access to all the good toys). For a little bit, 99L was taking in some drier air…however the high precipitable water content and higher OHC has apparently kept 99L for collapsing totally.
The NHC just recently lowered the probability over the next 5 day period, t0 MEDIUM (50%).
The following was available as of 8:00 P.M. EDT
8:00 PM AST Fri Aug 26
Location: 22.8°N 76.0°W
Moving: WNW 10mph
Min pressure: 1009 mb / 29.80 in
Max sustained: 30 mph
The biggest problem for the past 24-36 hours has been the presence of around 25-30 knots of shear over the NE portion of the system, blowing the thunderstorm activity away from where the vorticity cetner has been located. In addition to this, the shear spreads out the heat from the center (the warm, moist air that rises from the ocean, and the released latent heat). This robs the system of heat energy, not allowing for it to focus in more of a column, so convection is not able to grow, especially near the center. This shear was called for, however it occurred about 2 days earlier than forecast, but is only supposed to be brief.
In fact, wind shear values over 99L as of current, appear to be only 10-15 knots. On thing I have noticed is, the models have not been very accurate in the shear forecast with 99L as they were about 1 week ago. The current shear forecast still indicates for wind shear to relax with a semi diffluent flow being noted in about 42 – 48 hours, as 99L enters the FL. Straits and keys, with the re-establishment of the upper level anticyclone developing out over the eastern GOMEX. Albeit it doesn’t show too well in regular satellite loop imagery, IR2 loops still indicate some cyclonic turning, with some other vortices around 99L, mainly to the south and east. The system continues to move slowly WNW, and based on forecast steering, I expect this to continue for the next 48-72 hours, prior to making more of a NW motion in the eastern GOMEX. Though forecast steering indicates the Mid Atlantic ridge to still be in place, it weakens slightly. It is noted that a mid level feature either splitting from Gaston, or a portion of newly designated 91L, may undercut the ridge in about 3-4 days. The combination of these 2 factors may be what the guidance is seeing, hence the turn northward.
If the wind shear forecast is accurate this time, I believe we may see some improvement with 99L once it enters the FL. Straits, and then develop steady, but slowly upon engineering the eastern GOMEX.
Based on my very quick and breif analysis of things, I am concurring with the TVCN / TVCC guidance models at the moment (pointing toward FL. Panhandle). At the time of posting, I did not have the 00Z graphics, and the following is from 18Z.
Residents of the Bahamas, FL. Keys, and west coast of Florida through the Tampa Bay area should monitor this system, as heavy rains from this system, regardless of development, may cause urban flooding and flooding of low lying areas due to heavy rainfall and slow motion of the system. Florida west coast should begin seeing rainfall sometime on Sunday.
I will have a full update late on Sunday.
Have a blessed evening!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS