"Talking the Tropics With Mike": Long range potential - June 22nd

June 22, 2016 — A surface low continues over the W. Atlantic between the Mid Atlantic & Bermuda. Some slow subtropical development remains possible but no significant impacts to the U.S. as the low eventually gets swept out to sea by an approaching upper level trough.

Meanwhile... a pretty active tropical wave over the Western Caribbean has combined with an upper level low to produce quite a bit of convection. Shear is strong + there will be interaction with Central America so short term development is unlikely.

Thunderstorms over the Bahamas are associated with a decaying frontal boundary/surface trough - no organization indicated but an area to watch if the convection has any staying power.

SOME forecasters have been jumping on model development over the Gulf of Mexico by the July 4th weekend. I'm not quite ready to get on that bandwagon yet & have had to calm viewers that have seen other "outlets" jump on long term modeling that lacks any kind of consistency not to mention much backing from other models (that's why consensus forecasting is often a helpful tool). The American GFS model has been the most emphatic while some other models indicate little or nothing at all. Recent model runs of the GFS have backed off a good deal on intensity... delayed development until after the 4th... & shifted west over the Gulf. This back & forth at such a long range is why it's prudent & more responsible to observe & try to make sense of a situation vs. hyping something that is 7-10 days away. Yes - it's a big holiday weekend, but there still is plenty of time to diagnose the situation & to come up with a helpful & accurate forecast for you - the "clients".

* So let's take a look at the water temps. Plenty warm over the Gulf - well into the 80s.

* satellite imagery shows a nearly cloudfree Gulf while a tropical wave quickly moves into the Western Caribbean - this won't be an issue.

* shear is quite strong (20-30+ mph) - a negative for development

* one of my favorite - though not perfect - long range tools: velocity potential anomalies. In simplest terms, the green lines correlate to rising air which induces convection & can make for more favorable conditions for tropical cyclone development. The brown lines are the opposite - sinking air which has a tendency to limit convection. It's worth noting that "Danielle" developed within a vast basin of sinking air, so it's not impossible to have tropical development in such an environment but conditions are far more favorable when the overall atmosphere is unstable (air is rising) & moist. The rising air is related to the Madden-Julian Oscillation (MJO) & one can see a massive "pulse" over the W. Pacific - note all the convection. This large area of "rising air" should push eastward across the Pacific & eventually into at least parts of the Atlantic at which time we could see a spike in tropical activity. So for the Atlantic Basin we would be looking at least at the 2nd & 3rd weeks of July. During strong ENSO events, the velocity potential anomalies are generally less reliable, but the strong El Nino has ended, & the equatorial Pacific is in a nearly neutral state for the moment.