TROPICAL CYCLONE FORMATION: NONE
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(T. F. “Storm” Walsh III)
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CURRENT 2016 TROPICAL CYCLONE TOTALS:
TOTAL STORMS: 4
INTENSE HURRICANES: 0
StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 14-16
INTENSE HURRICANES: 3-4
Good day everyone!
Still very quiet over the Atlantic basin today.
Another Tropical Wave can be seen exiting the African continent. I am not expecting development of this wave given that easterly shear over this feature is around 20-30 knots at his time, along with still, some SAL over the vicinity.
Analysis of the Tropical Cyclone Formation Probability Guidance Product from RAMSDIS indicates vertical instability is below climatology over ALL of the Atlantic Basin sub-regions
Analysis of the global models this morning tends to indicate an upswing in tropical activity during the next 6-10 days, with the GFS being the most robust showing a large Tropical Storm that eventually recurves in a forecast break in the ridge near 50-55W. The GGEM indicates a much weaker system with only one closed isobar, and the NAVGEM a much weaker system and earlier in the forecast period.
The GFS has been indicating lower pressures IVO the Cape Verde islands the past few days, and has only had a couple of runs showing a developed system. Based on the MJO theory of an increase in activity 5-10 days after the MJO maximum in regional precipitation occurs over the east Atlantic and West Africa (which is the current situation regarding the 200 mb velocity potentials), climatology, and the forecast premise of increased 500 mb humidity levels over the African continent by day 6 and beyond in the forecast period, I cannot rule out this development, yet. Should this come to fruition, it is too early to speculate about strength or track, as one cannot base future track on 2 model runs, especially when we are speaking about a time period 10-16 days out in the forecast period, and given the fact steering currents CAN CHANGE in as little as 72 hours.
Before we get our hopes up as far as something to track and work with, I would like to see further, consistent runs of the GFS, and if the ECMWF model comes onboard.
I wanted to explain something briefly about a post I read on one of the weather groups I post in on FB. A gentleman posted about the AMO (Atlantic Multidecadal Oscillation), and the AMM (Atlantic Meridional Mode, commonly known as the Atlantic Ocean Tripole).
Based on the cold pool we’ve seen over a portion of the North Atlantic SST Anomaly maps, it does appear we have shifted more toward the cold AMO phase. Now, I mention this in that, the person writing the post mentions the AMO is not warm, but the AMM. He states that this, and the cooling of the Gulf of Guinea could play a factor during our busy time of the hurricane season.
First, the Atlantic Ocean Tripole. Current SST Anomalies tend to resemble what now appears to be somewhat of a tripole setup, albeit warm, cold, and warm anomalies are further north and somewhat misplaced, as compared to a “mean” positioned and optimal tripole, as compared by the current anomalies, and the tripole of 2013. The resulting effect is the warm anomalies in the far north Atlantic would see rising air or “lift” in the atmosphere, the colder anomalies indicative of sinking air, and again, warmer anomalies in the MDR indicative of rising air. This setup provides what we term “maximum net lift” in the atmosphere (which is required for cloud development and moisture in the atmosphere). The current setup “somewhat” resembles this, but again, is not exactly the same as the optimal or “mean” positioning. Given the MDR is warmer than the average, this may be an enhancing factor, should we get a break in the subtropical ridge being on steroids.
Secondly, the Gulf of Guinea. When SST Anomalies are colder than average, the colder water temperatures create a SST and MSLP gradient, which shifts the trade winds south of the Equator, close to Africa, from SE to SW. This allows for the ITCZ or Monsoon Trof to shift further inland over the west African Continent over the Sahel region, bringing more rainfall over that region. This has the tendency to cut down on African dust, and enhance tropical wave strength. The following is a fairly decent article from the AMS regarding this.
AMS CONFEX PDF ARTICLE
Based on analysis of the CFSv2 seasonal forecast, and modeling from IRI at Columbia Univ., SST anomalies are not forecast at the moment to cool in the Gulf of Guinea. We would need to see anomalies something similar to July of 2005.
Elsewhere, Tropical Storm formation is not expected during the next 7-10 days.
I will not be on the next 3 days, as I work.
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS