Saturday, September 15, 2007
Weather columnist Kevin Myatt: Fall's first cold front rolling in
Kevin Myatt is The Roanoke Times' weather columnist.
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I have often written about the push and pull between the tropics and the tundra defining our fall season.
This weekend's turn of weather displays that vividly.
The tropics arrived Friday with the remnants of Hurricane Humberto helping bring Southwest Virginia its first widespread, significant rainfall since early June.
The tundra rolls in today as a strong cold front brings the coolest push of air since the spring.
Temperatures by Sunday morning will likely be in the 40s in most places, with even a few upper 30s in the deeper valleys close to the Virginia-West Virginia border.
Recall that it was 100 degrees in Roanoke just three weekends ago.
Fall begins on the astronomical calendar Sept. 23, but on the meteorological calendar, it began Sept. 1 -- a date chosen mostly for statistical convenience.
Early September has not felt much like fall, but rather an extension of our all-time record hot August. Highs have been above 90 degrees seven days this month in Roanoke.
At least from this vantage point, this weekend's blast of tropical rain followed by Canadian chill does not look like the beginning of any long-term change from our patterns of drought or heat.
So the battle between the tropics and the tundra may only be a trickle in what has really been more like a desert for us this year.
No additional widespread rainfall is in sight, barring another quick-forming tropical system like Humberto that moves our way.
Tropical Storm Ingrid is spinning way down near the Windward Islands, but it is doubtful Ingrid will survive many more days. Even if it does, it looks likely to curve into the open Atlantic.
After the cool snap, with a few days of highs in the 70s and lows in the 40s and 50s, high pressure looks to build over us again from the west, bringing a return to above-normal temperatures by late next week.
Highs in the 90s become less and less likely as the sun angle gets lower and the days get shorter. Roanoke has never had a high of 90 later than Oct. 6, and hasn't had a high in the 90s in October since 1959.
But, with several days to end this month in the 80s, we still have a shot at this being our warmest September on record.
What a contrast that would be to last September, when the tundra won out and the average September high temperature was the coolest on record.
Humberto the incredible
The accompanying graphic details the explosive development of Hurricane Humberto on Wednesday and Thursday.
I didn't mention a word about tropical development in the Gulf of Mexico in my Wednesday column because what became Humberto was only a diffuse area of clouds, and hurricane forecasters were skeptical of its potential to develop.
Humberto is without precedent.
"To put this development in perspective -- no tropical cyclone in the historical record has ever reached this intensity at a faster rate near landfall," National Hurricane Center forecaster James Franklin said in an Associated Press article. "It would be nice to know, someday, why this happened."
