Monday, April 16, 2007

"What a day, what a day..."

Saturday afternoon I got the word from my chief meteorologist Jeff Crum that he had "pulled the trigger", meaning (as I had anticipated) going into active work mode for Sunday in anticipation of what was then expected severe weather overnight. My particular forecast office has no person hired to do 'live' weather on weekend mornings, so when severe weather threatens we make contingency plans. You roll up your sleeves and have at it...

Walked in the door at work at 2:15 AM Sunday...and walked out the door at 2:51 PM Sunday. That almost says it all. Even if you don't live in the Carolinas, you are most likely even remotely aware our weather exploded toward the noon hour. What was originally a tornado watch box in eastern NC quickly was expanded by the Storm Prediction Center in Norman, OK (SPC) to cover virtually all counties but the mountains, through 8 PM. What had been a classic, quiet 'dry slot' in the water vapor imagery over the Triad in the morning (with an exception) became a radar field of 'hornet' cells that literally swarmed the radar screens.

(damage reports from Sunday through the SPC -
click to enlarge)


The 'exception' was my first uncomfortable tip-off. Thought the tornado watch box was east of the Triad by a couple of counties, a line of cells exploded from Montgomery through Randolph and up into Alamance Counties on the Triad's eastern fringe. And they were impressive, with warnings popping left and right shortly after 9 AM. While not in the watch box, those cells were uncomfortably close to it, though admittedly my radars did not reveal one single rotation marker...just 60 mph straight winds, large hail, and torrential rain. You could have taken an Exacto knife and cut the western edge of the storm line, with the rest of the Triad either dry or with the lightest of showers falling. Just an eastern thing.

But what made me uncomfortable were the high dewpoints. In that zone the dews approached 65 degrees, with dews of only 52-55 degrees one to two counties away to the west and north. That bubble of instability held it's ground, and helped in feeding the maelstroms that erupted just a few hours later.

A boundary aloft began working roughly parallel to the NC-SC border and slowly progressing northward around 11am...and at the snap of a finger storms grew along that line and moved with it northeastward, many cells creating warnings in very short order. It was painfully obvious my day was far from done until Monte Montello came in to pick up duties for the second half of the day.

I've never ridden a bronco, and I have no plans to ever do so. But if you are in weather, such an event has some similarities...you have a short countdown and you give it all you've got, holding on for the wild and unpredictable ride...only there isn't the pain involved of hitting terra firma. Below I've listed a few selected storm reports from the NWS, as well as some preliminary data upstream in the northeast...many reports have yet to come in, but this is what I dug up at 1 AM from various sources:

GREENSBORO - HAIL FROM PEA TO NICKEL SIZE NORTHWEST PORTION OF GREENSBORO. WINDS TO 60 MPH NORTHWEST PORTION OF GREENSBORO AND SOUTHWEST PORTION OF GUILFORD COUNTY. (RAH)

COLERIDGE, RANDOLPH
COUNTY NC - ROOF OF THE FIRE DEPARTMENT IN COLERIDGE BLOWN OFF. (RAH)

(NUMEROUS HAIL REPORTS OF .25" TO 0.88" HAIL THROUGHOUT THE TRIAD)

GREENSBORO - FLASH FLOOD - 1700 BLOCK OF ROCK CREEK DAIRY ROAD FLOODED AND IMPASSABLE IN SOUTHEAST GUILFORD COUNTY. BRIDGE UNDER WATER ON HIGH ROCK ROAD IN NORTHEAST GUILFORD COUNTY.

MULBERRY, SUMTER COUNTY SC - *** 1 FATAL, 3 INJ *** A NWS SURVEY DETERMINED THAT A TORNADO...OF MAGNITUDE EF3...WITH ESTIMATED WIND SPEEDS AROUND 140 MPH...DESTROYED SEVERAL MOBILE HOMES NEAR US HGY

Other notable reports I found:

Boone, NC 1AM wind gusts of 61 MPH
Ashland, Ashe County, NC 6" of snow at 730 PM Sunday
Charleston, SC - Ravanel Bridge - 71 mph wind gusts
Weston, CT - 7.50 inches of rain at 11PM and still falling heavily
Warren, VT - 17.0 inches of snow at 9:45 PM and still falling heavily

Mount Washington, NH - 18 degrees, with winds gusting to 99 MPH.


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