We’ve been joking today the Labor Day is considered the ‘unofficial end of summer’ holiday. Well not this year as Columbus Day will have that distinction this year. In fact, our high and low for the day will be at or just above what is normal for the 4th of July!
What has been remarkable about this October heat is how muggy it has been and that has been reflected in the overnight lows. Temperature can’t fall below the dew point, so looking at the low temperatures is the gauge for determining the mugginess. Our lows have been in the upper 60’s to low 70’s, very typical for summer, then take into account the longer nights now and you’re really saying something. We’ve broken or tied 4 ‘high-low’ records this month, and likely have 2 more that will fall Monday and Tuesday. Our dewpoints around 70 are truly amazing for this extended period of time. Truthfully, we may have set a record for the highest October dew point last week when it got to 73, but that’s not a stat that is kept. One other highlight…we’ll be coming in second place for the most consecutive 80 degree days in October when this wraps up Wednesday. That will give us 10 in a row which will be just shy of the record of 12 from 55 years ago in 1963 (and those occurred in the middle of the month). Not surprisingly that was a drought year with only .33″ of rain that month…we had that in 5 minutes Thursday night! Other fun fact, and how dry 1963 was, while highs were in the 80s the lows were in the 40’s and 50’s…30 and 40 degree diurnal swings…that’s like a desert!
So as the atmosphere likes to do, balance is coming. While we’ve been baskng in the summer warmth, winter came early to the west and northwest US and Canada. You can see in the map above the big ‘U’ shape of yellow and green. That big cold trough has been sitting out there. The boundary between our heat ridge and that trough has been a jet streatm conveyor belt for epic rain from Texas into the Midwest and will continue into midweek.
When this pattern breaks, and it will, it’s likely to be a violent transition somewhere. Let’s show you the end result first before we get into the catalysts.
A huge drop in temperatures is poised to replace the near record warmth. The temperature drop will be 25 to 35 degrees by the time it all settles in through early next week taking our highs from 20 above normal to 10 below normal. The weather pendulum ALWAYS swings and one extreme usually begets another.
So how does this pattern finally break down? As is often the case this time of year, the tropics are involved. Late last week we started watching the Caribbean as a posssible development area. Over the weekend, Michael formed and has intensified fairly quickly. The water in front of it is bathwater warm and overall the environment looks favorable for rapid intensification. The National Hurricane Center brings it into the Florida Panahandle as a 100 mph hurricane Wednesday afternoon. If it comes that fast, that’s probably the top end as it won’t have time to do much more.
However, the European model is significantly slower, not bringing it in until sometime on Thursday. It’s slower to break down the massive ridge that has brought our heat. Given its strength and duration so far, that may be a more likely scenario. Michael will travel around the periphery of that big high and it will eventually be picked up by that jet stream that is bringing the aforementioned heavy rain to our west. That’s how heat from the tropics gets dispersed. Anyway, back to the slower European solution.
This is just a model forecast (but it is the normally reliable European), but if this verifies then what is likely a major hurricane is lurking off the Florida panhandle. With more time over the warm water hurricane food the central air pressure would be down in the 950mb range which puts it smack dab in the middle of what is normally a category 3 storm. A lot of times the NHC plays catch up with rapidly developing systems. Given what the Carolinas just went through with Florence, let’s hope the NHC solution is the correct one. Regardless, a significant storm looks to be impacting the Gulf Coast this week. What may also follow is another corridor of heavy tropical rains inundating the Carolinas.
Which leads to the final thoughts on this week and the overall pattern…and it’s kind of a chicken/egg thing. Many times in the fall significant transitions to cold follow tropical systems. I was in South Carolina for Hugo and remember how cool and clear the air was in the days after that powerful storm. It was flannel shirts during the fund raisers we did for the coastal residents. Sandy produced feet of snow in the Appalachians. Michael will pull the deep trough and its cold eastward, so it’s the spark that ends our remarkable heat. But again the chicken/egg…is the tropical system what causes the transition, or does the tropical system get created because of the pattern.
Deep thoughts getting you started for this definitely not boring 2nd week of October. What will also be interesting to see, if we get any prolonged fall weather (you know, the good stuff upper 60’s and 70’s) or if this will be like the winter/summer transition we just experienced where we had very little spring and it basically turned on a dime.
We’ll continue to track Michael’s progress this week. Now go and find your jeans and jackets, you’re going to need them.
All the best…
Bill
