TROPICAL CYCLONE FORMATION: NONE
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: 5
INTENSE HURRICANES: 0
StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 13-15
INTENSE HURRICANES: 3-4
Good day everyone!
The associated convection and thunderstorm activity with the low that moved into the FL. Panhandle, continues to remain quasi-stationary, with a possible very slow drift in a general westward motion. Based on satellite loop images, and information contained in the NHC Tropical Weather Discussion, a 1010 mb low was situated early this morning near 31.0N;88.0W which is located just on the extreme western portion of the FL. Panhandle.
You’ll note in satellite loop imagery there is some banding features associated with this area. I am attributing this to the low center being very close to the coastal area, being able to draw in moisture from the Gulf. There is in fact, based on the upper level wind pattern from CIMSS, a definite outflow channel over the eastern portion of this low, circling clockwise around to the NW of the low..hence the fanning out of the cloud pattern. Seeing how the actual low center is inland, I am not looking for development.
Based on current steering, this low is in a weak to non existent steering pattern at the moment. Based on analysis of the forecast steering layers maps, this could remain stalled for the next 24-36 hours, and then begin to move off to the west or WNW.
Residents of the Gulf Coast States should monitor the progress of this low, and local NWS Office statements and warnings, regarding the possibility of flooding and flash flooding due to copious accumulations of rainfall during the next 36 hours.
The following NWS map is interactive…click on your area, or area of interest for the latest warnings and advisories from your local NWS office.
Elsewhere, the wave approaching the SEUS continues to show waxing and waning convection. I am not too concerned with this feature developing, however the current wind shear forecast does indicate upper level winds may remain marginally favorable for some possible slow organization during the next 24 hours. This feature is also embedded within weak steering at this time, and is drifting toward the NNW. This motion should continue during the next 24 to possibly 36 hours, before forecast steering shows more of a track toward the U.S. coast, possibly affecting the GA to southern NC area.
A small area of convection is noted within the ITCZ in the eastern Atlantic, however I am not expecting development of this feature, given the very narrow band of TPW associated with it.
MIMIC TPW LOOP
Looking at the overall picture, it is fairly quite as we enter the portion of the season where the “ramp up”‘ climatologically begins, as the period from Aug. 10 to Oct 10 is considered the busiest portion of the season. Again, we have had seasons in the past, where tropical storm activity did not begin until near the very end of Aug. The 1967 season did not see it’s first storm until 28 Aug., with the season ending with a total of 8 storms. Should this lull continue and we don’t see anything until months end, bear in mind we have 5 storms under our belt already. The season of 1984 saw a sub-tropical system beginning on AUG. 18. The first NAMED system did not appear until 28 AUG. This season went on to have a total of 13 storms, counting the sub-tropical formation. So what I’m pointing out is, don’t let your guard down due to the lack of activity, as based on analysis of various entities affecting the Tropical Atlantic at the moment, we could very well remain in a lull, pretty close to months end.
Right now, the Atlantic is still being plagued by African dust or the SAL. The dust and warm SAL create an inversion near the mid and upper levels of the atmosphere, pretty much creating a “cap” on convective growth. The problem is twofold at the moment. First, the Atlantic sub-tropical ridge has once again strengthened and positioned itself further to the NE, which allows for the eastern periphery to be closer to Africa. This eastern portion, because it extends itself to over the Sahara, it is coined the “Sahara High”. This lifts the dust and of course, transports it out over the Atlantic. Of course, with the strengthening of the ridge comes subsidence, or sinking air (dries out the atmosphere). This is also being reinforced at the moment, twofold. You heard us weather guys speak of the MJO/200 mb vertical velocity potentials a few times. Again, the MJO signal plays the biggest factor in June – July, then again Oct0ber-November. Tropical systems during August and September can still be separate entities from the MJO, not to say that a favorable MJO pattern is not a plus. You can see in the following graphics of 3 of our busy seasons, that the MJO for JUL-SEP was pretty much either over the WPAC and Maritime Continent within the peak of the season. However, at the moment, we have a large scale, and forecast large scale Walker Circulation pattern based on the 200 mb Vertical Velocity Potential anomalies. I borrowed a graphic, courtesy of my colleague Levi Cowan (Tropical Tidbits site) showing a recent update to the 200 mb velocity potential forecast. Albeit tropical systems can still develop with positive velocity potentials present, although difficult, these anomalies are stronger than what we would expect for this time of year. So in effect, the sinking air from the 200 mb level, is reinforcing the subsidence created by the stronger Azores/Bermuda high. This condition, looking at the 200 mb velocity potential forecast could last until very close to, or until months end.
However, analysis of the GFS and ECMWF seems to indicate lowering of 500 mb anomalies over the Yucatan Channel in the 5-7 day period (GFS), and a small, closed feature over the Cape Verde islands by day 10 (ECMWF) This COULD occur, based on some things I noted in analysis of the MSLP forecast (NASA and ECMWF), as well as the dust and TPW forecast.
Beginning in about 5 days from now, the subtropical ridge is forecast to slide back south and to the west, become centered just west of the CATL. As this happens, the ridge is also forecast to weaken, which again should allow for the slowing of easterly winds off Africa, allowing for surface convergence. The ECMWF does back up the NASA forecast, and is only 1 mb higher in pressure than the NASA model.
Although dust is forecast to remain somewhat prevalent, the TPW forecast still calls for an increase in TPW throughout days 5-10. Having put this model into motion during analysis, it is noted a large area of TPW over the Caribbean does acquire rotation, which would tend to indicate a strong tropical wave or tropical system. Similar motion was noted in the TPW animation with TPW off the African coast in about 8-10 days. My only reservation is, will the amount of TPW be enough to overcome the African dust and dry air. Bear in mind, that Earl, prior to becoming a named system, was barely a discernible feature, until coming under the area of high TPW. So, it appears as if it is going to be a wait and see situation, to see how all of the factors evolve and play out.
0.50 inches or less = very low moisture content
0.50 to 1.25 inches = low moisture content
1.25 to 1.75 inches = moderate moisture content
1.75 to 2.00 inches = high moisture content
2.00 inches or above = very high moisture content
Elsewhere, Tropical Storm formation is not expected during the next 5-7 days
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS