Tropical storm Philippe is still hanging around even though it has been plagued periodically by strong wind shear. Philippe could even briefly attain hurricane status in the next day or two before it likely becomes absorbed into a frontal system and heads out to sea. Whatever happens with Philippe, it appears as of now he will not threaten land although Bermuda still has to be watched.
A potentially bigger issue is that global models are showing tropical development in several days in the western Caribbean and Gulf of Mexico. As we see a strong upper ridge form over southeast Canada, this is the type of pattern that could certainly favor lower pressures and possibly tropical development to the southwest of it which would be generally the western Caribbean and eastern Gulf. The 00z ECMWF does show a tropical storm by Sunday in the Gulf being picked up by a trough and hitting the east-central Gulf Coast early next week and bringing rains to the southeast US. The ECMWF Ensemble members show a wide range of possible solutions. The Canadian model shows a system as well in the Gulf and eventually turns it east across Florida. The GFS shows mischief as well but it isn’t clear which features it is keying on.
The bottom line is that the 3 major global models are showing a tropical cyclone in either the western Caribbean, eastern Gulf, or near Florida in 5-8 days and this is a valid scenario and could end up threatening the US, so stay tuned.
General Weather Pattern/Thoughts
As we head deeper into October, the general pattern is clear, an emerging cool pattern for the West, probably persistently for the NW but maybe not so much for the Southwest/Southern Rockies, a very warm pattern for the northern/central Plains, Midwest, and Ohio Valley, a warm but not as warm pattern for the Northeast US, and a near to slightly above normal pattern for the Southeast/Gulf Coast. This is via a large trough in the West, a strong anomalous ridge over the northern US/Southeast Canada, and a weakness under this ridge along the Gulf Coast. In looking back at past October with a weak La Nina, you get about 10 years that fit the bill, and a composite of all those seems to fit pretty well the current and evolving pattern across the US. However, many of those years featured either or both a +PDO and a –AMO. We are in a strong negative phase of the PDO and a warm phase of the AMO. The only year that comes close to matching is 2000 with 1950 not horrible either. I have attached the October 2000 500mb and surface temperature anomaly map for 2000 and you can see many similarities what we have this year. The year 2000 also featured a strong negative QBO which we are likely heading towards but are not at yet.
In general this pattern may persist well into the month. Both 1950 and 2000 featured very cold Novembers for the eastern US with a –NAO and we do see the AO and NAO trending down some late in the 15 day forecast period but certainly not quickly as of yet. Right now I think we are heading towards a cold late Fall/early Winter pattern, but I will save that discussion for my winter outlook due out on October 30thor thereabouts.