Good day all!
Going to do a little something different here today. I wanted to go over a little bit of the state of the tropics. Albeit some of the parameters or “signals” I look at for the upcoming hurricane season are not totally established, I do want to share what parameters I have, and should some of these continue toward negative, it would reinforce the premise of another above average hurricane season.
First, the current SST Anomaly map indicates continued slow cooling in the Equatorial EPAC. Based on this , and current state of the atmospheric pattern, values suggest a still ongoing NEUTRAL ENSO pattern, albeit the SST anomalies have become a little cooler. The map animation from Washington State University will how how this has progressed.
Looking at the SST Anomaly maps, there are a few things one can notice.
1.) The Atlantic Ocean MDR is at or slightly above normal anomalies
2.) The Atlantic Ocean Tripole is noted (warmer anomalies in the MDR, colder anomalies around 30N, and warmer anomalies north of that) becoming established. This phenomenon allows for “lift” in the atmosphere in the Tropical Atlantic during the season, or what we cal net upward motion.
3.) The presence of continued cooling in the Equatorial Eastern Pacific, which at the moment is producing ENSO NEUTRAL conditions. Continued and sustained cooling could induce La Nina conditions for the season, albeit the Climate Models indicate Neutral conditions for this season.
4.) The Gulf of Guinea has cooled somewhat, and is not as warm as earlier. The significance of this is, with warmer anomalies, the ITCZ or Monsoon trof hangs out further south, with more rainfall over the Guinea region of Africa. Cooler anomalies induce changes to where the ITCZ or Monsoon trof extends further north than average, bring rainfall to the western Sahel region.
6.) Indian Ocean anomalies have appeared to continue to cool slowly. Cooler sst anomalies in the eastern portion of the Indian Ocean are indicative of a negative IOD, while the reverse is a positive. During a negative IOD, the monsoonal circulation off of west Africa does not become interrupted, which allows for aid in more storm formation. Based on the forecast of the IOD Index, a slightly negative IOD is forecast this upcoming season.
7.) The Southern Oscillation Index has recently showed a continued climb into the positive scale, which indicates Trade Winds blowing from east to west, which if remaining this way, would reinforce neutral conditions, if not a change to cool over time.
8.) The NAO has been negative, and is forecast to remain negative over the next week or two, which reduces trade winds in the Atlantic, thereby reducing wind shear, and allowing for the sst’s to warm. Wind shear in the MDR, even though around 30 knots or so, is below climatology at this time.
9.) Although the QBO is no longer used as a forecast tool, USUALLY a positive phase leads to more hurricane development. This feature could hit positive by the beginning of the season.
So, pretty much in essence, these factors are beginning to point to conditions favorable for another above average hurricane season, although these can change either way during the next 2-3 months. Once we get into May, I’ll be looking at everything again to see where we stand.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced)