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Good day everyone!
The tropics are once again quiet this morning. Satellite imagery does indicate some thunderstorm activity near South America, however development will not occur.
Water vapor imagery shows plenty of dry air covering the Atlantic Basin, courtesy of the recent SAL outbreak, and a 1031 mb – 1032 mb Atlantic ridge. You have heard me mention the strength of the ridge over the past couple of forecasts…let me shed some light. What I do as a forecaster is compare the phase of the NAO (North Atlantic Oscillation) and the strength and surface presentation of the Atlantic ridge. The NAO has to do with the strength of the Icelandic low and Azores/Bermuda high. When the pressure correlations between the two are strong (deeper Icelandic low, stronger A/B ridge) we are said to be in a positive phase of the NAO. The opposite of the two places us in a negative NAO phase. Now, albeit the current NAO and the NAO forecast is showing slightly positive, then hovering near neutral to a weak negative, the current pressures for the A/B ridge indicate a little stronger NAO. Regardless, the effect the stronger ridge has on the Atlantic pretty much explains the inactivity we are seeing. Th stronger ridging affects the ocean in numerous ways. The stronger ridge means stronger sinking motion over the Atlantic. Meteorologically speaking, this is what we refer to as subsidence. The air sinks, and as it does, it warms by compression, which dries the atmosphere (hence the dry air and lack of instability over the Atlantic).
Next, this induces quicker trade winds at the surface. Now granted, evaporation is needed to some extent to induce the release of latent heat into the atmosphere for storm formation…however faster trade winds cause a greater evaporation rate, and basically takes any heat released, and spreads it over a larger area. This latent heat needs to be released in more of a column, so it may rise and cool for condensation. This is why we are seeing the lack of clouds. So, these are just some of the reasons I have mentioned I am not looking for anything, until the ridge can weaken to around 1026 mb – 1024 mb. In my research, I have found this pressure is pretty much the “mean” strength for the Azores High.
Analysis of the Global Computer models does not show ANY tropical development over the next 10-14 days. However, the GFS in about 10 days indicates a very weak 1012 mb low SW of the Cape Verde islands. I am not too concerned with this at the moment, as analyzing various levels of the atmosphere, from surface to 500 mb, there is no indication of an associated cyclonic wind field at that time. IF this low does materialize, it will be monitored, as the upper level pattern, based on the current long range GFS shear forecast, could be extremely favorable near that time frame for a short period, with an 200 mb anticyclonic flow, and no detectable wind shear values.
Elsewhere, the most favorable area over the next 7 – 10 days is forecast to be off the SEUS coast, down to the northern Bahamas area, as far as the upper level wind pattern.
I am not expecting tropical storm formation 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
OFFICIAL SKYWARN SPOTTER (ADVANCED)