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(T. F. “Storm” Walsh III)
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Good day everyone!
Satellite loop imagery indicates the shower activity noted near Panama and Nicaragua has diminished, and wind shear can be seen blowing upper level clouds to the east.
Analysis of the global models this morning does not indicate any development during the next 7-10 days. The latest run of the NCEP/EMC Cyclogenesis ensemble models has also dropped the probabilities it had yesterday for possible development over the Gulf of Honduras.
NCEP / EMC CYCLOGENESIS TRACKING
Wind shear is fairly high over the Caribbean and GOMEX, with the following pattern forecast to remain in place over the next 10 days.
GFS 240 HOUR WIND SHEAR
I will continue to monitor the tropics, as we all know how quickly we have seen conditions change over the past few seasons.
Tropical Storm formation is not expected during the next 7-10 days.
Since nothing is expected over the next few days, I wanted to take this time to try to explain how El Nino, La Nina, and El Nino Modoki conditions affect the Tropical Atlantic during our hurricane season. Lets start with La Nina / Neutral conditions: This is when we see much colder SST Anomalies coming off the west coast of South America, which extend toward the west. Warmer SST anomalies are therefore confined the the WPAC, near Australia. This sets up a circulation, that does not allow wind shear to affect the Atlantic Basin. I know the graphics look the same, however if you note the arrows, the circulation setup is a little stronger with La Nina.
LA NINA / NEUTRAL CONDITIONS
El Nino, is when we see the much warmer “tongue” of water coming off the South American west coast, and extending back to the west. Again, this creates a much different atmospheric circulation / pattern due to extra heat being released from the ocean, and rising over the western portions of the U.S. This allows for the familiar “sub-tropical jet” or southern jetstream branch to activate and become very strong. This in turn helps to create the strong westerlies across the Atlantic basin.
EL NINO CONDITIONS
El Nino Modoki, focuses the energy and heat more over the Central Pacific, to where the atmospheric circulation is far enough away from the U.S., that it has no real affect over the Atlantic MDR.
EL NINO MODOKI
The following graphic is linked to an article from Climate.gov, explaining how each condition affects the Atlantic basin.
Next, just something brief on one basic for tropical cyclone steering. The NAO (North Atlantic Oscillation) plays a part in steering these systems. I’ve noticed folks speak of the subtropical ridge, in when it is fairly strong, will push systems into the U.S. coast. Actually, this is a misnomer, as if you strengthen the ridge upstream, then you strengthen the trof downstream…in other words, the trof on the west side of the subtropical ridge will be stronger, allowing for storms to steer toward the north…per se’. The following graphic is linked to an article regarding the Negative and Positive phase of the NAO during hurricane season.
The BOM ENSO Wrap Up site is supposed to update tomorrow on the Nino 3.4 forecast. Once I can analyze this, and the updates from other climate models, I will probably have another revised seasonal hurricane forecast for the season. Right now, most of the evidence is pointing toward ENSO Neutral, warm biased to El Nino Modoki conditions. This should be my last revision, unless a major change occurs in the climate models in June.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS