There are few places in the United States that experience the rapid and sometimes dramatic changes in the weather as we do here in the panhandles. This past week only proves that if you do not like the weather in the panhandles, simply wait a few hours and things will change.

The image on the right shows the weather pattern in place that contributed to the severe storms that occurred on Thursday April 20th, 2007. There were a few key ingredients that lead to the severe weather, and especially the strong winds. A deepening upper level low pressure system was digging south into Arizona. This provided southwest winds aloft and also generated a short wave that moved over the panhandles. Short waves enhance lift and help support thunderstorms. They are like little bursts of energy that can trigger storm development. In addition, the winds above the ground were very strong. There was an upper level jet in place, which is an area of strong winds surrounded by weaker winds. This area is noted in red on the map to the right.

There was also plenty of moisture in the atmosphere and the air was unstable. However, the air near the ground was actually a bit on the dry side. Dew points only reached the 40 degree range. This prevented the high amounts of energy typically associated with widespread super cellular storms, and also kept the precipitation totals relatively low. The image on the left displays the observed rainfall totals from the storms that occurred on April 12th into the morning of April 13th (click to enlarge). The highest rain totals were barely over an inch, and these locations witnessed multiple storms during the event. Most locations only saw a few tenths of an inch or rain.

Upper air soundings can tell a forecasted what type of storms to expect. The green line represents the dew point temperature and the red line represents the ambient temperature. When the two lines are close together, then you have high relative humidity or a lot of moisture in the air. Notice that near the ground (the bottom of the graph is the ground level) the two lines are spread apart. This feature is known as an inverted " V " sounding. Inverted " V " situations can often imply strong winds, possibly even downburst winds. The multi colored lines on the right side of the graph indicate wind speed. Notice that the winds become very strong (around 50 mph - the graph is in Knots, so 40 Knots = 46 mph) just above the surface. When the thunderstorms developed, they moved with a forward speed of around 45 mph in general. In addition, the storms were able to drag down these strong winds to the surface and in the process the winds accelerated causing downbursts and very strong strait line winds. This sounding also indicated that tornado potential was low.

So what happened in Amarillo? Was it a tornado or just straight line winds? Well, we conducted damage surveys on Friday April 13th, and the verdict was....straight line winds as a result of a downburst. To read the public information statement concerning the damage surveys, please click here.

Some people seem disappointed to find out that the damage was associated with downburst winds and not a tornado. Certainly it is very exciting to know that a tornado passed near your house. However, buildings, trees and power poles do not care if the 90 mph winds were rotating or straight…nor should a human care if the debris flying toward them at 90 mph came from rotating or straight winds. The point is that 90 mph winds will cause major damage to property and are extremely dangerous to humans. Whether the winds came from a tornado, a downburst, or a hurricane does not change the fact that winds that high are very dangerous.

Did the winds in fact reach 90 mph in this case though? Yes. In fact, the peak winds were estimated to be in the 90 to 110 mph range! There is a KVII News schoolnet observation site at the Discovery Center that registered 94 mph.

As the storms moved east, strong winds were reported in Armstrong and Carson counties, but current estimates put the strongest winds here in Amarillo.

But severe storms and winds were not the only story of the day. The thunderstorms lingered into the morning on Friday April, 13th but soon ran into cold air across the northern panhandles. This cold air allowed the prcipitation to transition to snow around 5:00 am.

Some of these snow bands dumped over 6 inches of snow in areas near Pampa. The image on the right shows the snowfall map from the storm. Notice the area of higher snow totals from Borger to Pampa. A snow band developed in this area producing localized heavy snow totals with now snowfall just 30 to 40 miles south of Pampa.

The images below were taken here in Amarillo during the snowfall.