Monday, August 20, 2007

Erin Almost Became A Hurricane Over Oklahoma

I was watching Erin's rapid intensification in awe here last Sunday morning.
The storm's center had become completely wrapped in moderate to heavy rain- and for several hours Erin even had an eye west of Oklahoma City.

The following is a witness account- a fellow 'storm chaser'- Rocky Rascovich- who was underneath Erin that night...

"I think I may have witnessed one of the most unusual weather events in recent time... right here at my farm in Piedmont, OK.

The remnants of T.S Erin, (which if you remember was downgraded to a depression last Wednesday morning just after it crossed the TX. coast near Corpus Christie..then spun itself through the hill country, then on toward Childress yesterday, still, the circulation intact but with winds generally 25mph or less)... decided, quite magically through the ever mysterious processes of our atmosphere.. to rapidly increase in strength starting last evening. Several tornado reports came in from SW Okla. then around midnight, the wind gradually started picking up here at the farm. Probably around 10-20mph from the east. Lightning was flickering frequently across the southern and western horizons. We had a few bands of rain come through earlier starting in the mid afternoon, infact I saw one storm come over downtown OKC that had exhibited some nice banding and inflow cloud spikes in the mid levels at around 5pm.

Cutting to the "chase", the real action got underway around 1:30am with considerable cg activity near the house along with 15-30mph winds that backed more from SE to E. At around 3am, I was in bed and Dee alerted me that a TOR warning was issued for Canadian County (my home county west of OKC). At that time, winds still weren't that bad but were increasing and cg activity was ramping up again.

A short time later, maybe around 3:15, I could hear my skylights in my bathroom whistling and lots of commotion going on, I got up... naturally, and lo and behold, it was mayhem happening, winds sustained at least 50mph, gusts over 60 right out of the east, and a profuse amount of rain wildly whipping by. Lightning activity was still there but was happening much less frequently.

This continued unabated and actually increased as the minutes went by. Between 4 and 4:45 was the peak of the storm. Winds were rarely less than 40mph, most of the time sustained at least around 50-55, peak gusts I estimated was around 65mph, not out of the question, 70. Wind direction for the most part was close to due east, maybe a little ENE at times. Rain was coming down aprox. 2-3"/hr

Starting around 4:45am, winds suddenly abated to around 20mph or so but a couple of times, a period of a minute or two, winds would suddenly increase to around 40-45mph out of the E/ESE. Interestingly, the gusts were not accompanied by any increase of rain, when the sudden wind surges hit, the rain at that time was generally light.

At 5am, our winds came down to less than 15mph, the rain temporarily lessened to a drizzle, we were in the "eye" of this storm... I was glued to KWTV ch. 9 (other channels were not coming in)... my satellite TV was out and the internet went down, so I was only able to see the radar through the tv. I soon after went back to bed, awoke briefly around 6:30 to strong S or SW winds and rain again... and a fair amount of lightning. Conditions gradually improved after 7am.

To me, this was a shock and awe moment, trying to figure out how this storm could actually strengthen... close to 72 hours after landfall, way up here in Okla. My guess is that it tapped into a theta E rich low level jet that was juxtaposed perfectly to feed into the remnant centre of the storm, thus, gave it that boost.
Temps and dewpoints were already reminiscent of that of the tropics to begin with, so it had that to feed off of too.

Despite my lack of the more indepth knowledge that you may have, I'm extremely interested in reading what perpetrated the sudden resurgence of strength, how often this type of phenomenon occurs and other historical accounts of similar incidents.

This sure has been one crazy year for weather here in Oklahoma! "
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