OVERVIEW:  Our projection for October was maintained this week for a near to slightly below average (0.0°F to -2.0°F) temperature departure for the month as a whole, with the expectation of several cooler than average stretches this month despite the warm start. November projections were introduced this week for a near to slightly above average (0.0°F to +2.0°F) temperature departure, using long term climate guidance and global observation trends.

• Seasonal changes are going to be become more noticeable in the weeks ahead as we continue to lower average highs/lows, and that downward process accelerates from this point forward to about a 3.0°F drop per week. The extreme heat is likely behind us, but we are beginning October on a much warmer than average note, albeit temporary. Climate models have continued to suggest an up-and-down temperature pattern in October, but more frequent occurrences of at least slightly below average temperatures. This allows the month as a whole to lean very slightly below average. The current expectation for November is, for at least the first half of the month, temperatures lean slightly milder. 
   
• The Madden-Julian Oscillation (MJO) is currently in a very weak phase 8 signal, and is expected to quickly collapse into the Circle of Death (COD) or NULL phase over the weekend. Once we near mid-October, both the GEFS extended and EPS weeklies are suggesting a phase 2 propagation, which generally signals milder conditions a few weeks later – supporting the milder start to November current outlook. Hurricane activity should remain limited at best with a strong El Niño increasing Atlantic shear despite reaching the peak of Atlantic hurricane season September 10th. In fact, this is the longest we’ve gone without an Atlantic Basin hurricane since 1966 in the modern satellite era, which is pretty remarkable. It is also the longest stretch in the pre-satellite era since 1914… a season where no hurricanes were present, or at least none that were documented.

   

• A composite average of the Sea Surface Temperature Anomalies (SSTa) in the ENSO regions places it in strong El Niño territory currently. The following are Coral Reef Watch Sea Surface Temperature Anomaly values referenced in this context. From west to east across the Pacific, the Niño 4 (west-central Pacific) is currently the “coolest” region at +1.2°C, whereas the Niño 3.4 region (east-central Pacific) is currently at +3.3°C. The eastern regions of Niño 3 (east-central Pacific) is currently +4.1°C, and Niño 1+2 region (near the Peruvian coast) is at an astounding +5.3°C as of September 30th. A near-record strong El Niño Fall is likely to continue, and is currently East-based.

   

Average high temperatures are currently in the 69-74°F range from north to south across our coverage region, which is about 3°F lower than at this point last week. The drop off in temperatures are now accelerating downward throughout Fall at about a 3°F per week drop. Any above or below average stretches listed in the outlook will be relative to seasonal norms at that time, and it is important to note that cooler/warmer periods will be relative to the time of year we are talking about. For example, the below average temperatures listed for the October 6th-7th period features highs in the 60-65°F range, coming at a time when average highs are in the upper 60s to lower 70s. Use the average highs/lows chart below providing transparency for what average temperatures are at each corresponding location through November 15th.