Saturday’s severe weather episode was far from a tornado outbreak, but storm chasers put in the effort and captured a few highly photogenic storms. Most of the documented reports of tornadoes stemmed from four supercell thunderstorms, with the strongest one occurring southwest of Great Bend, Kansas. The following Base Velocity radar snapshot shows this particular supercell near its prime over Pawnee County. Many storm chasers in the area took note of the impressive signature on radar and moved in to intercept the apparent tornado. The following chaser videos document this particular storm:
Saturday’s Tornado Video Highlights
Not to be outdone, there was also a very photogenic tornado across western Nebraska. The picture below was taken by Allison Shearer McBride.
An abnormally quiet spring continues across the U.S. with record low tornado numbers over the past year. With only 248 tornadoes (preliminary) to date we are well below the ’05 – ‘11 average of 692 tornadoes. The quiet severe weather season has been aided by a combination of spring snowpack and cut off lows/ blocking patterns. Things do, however, look to finally change and become more active in the coming days.
Beginning this weekend an upper level trough will make its way across the Inter-mountain West. As it approaches the Central Plains, lee side cyclogenesis will help promote southerly flow across the Central United States. This will advect rich moisture (a key ingredient for severe weather that’s been missing the past several weeks) from the Caribbean and Gulf of Mexico northward into the Plains states.
Initially, severe weather will be possible Thursday and Friday within the warm air advection regime; however, meager shear and substantial capping will limit the overall severe weather threat. Heading into the weekend a more potent severe weather risk will evolve across the Central-High Plains, eventually shifting towards the east/south-east.
The severe weather risk on Saturday (outlined below in red) will primarily feature large hail and damaging winds, though isolated tornadoes cannot be ruled out. Despite abundant moisture and instability, the tornado threat will be limited by the lack of a consolidated trough and a rather weak and unfavorable wind shear pattern (veer-back-veer profiles).
On Sunday the primary risks will once again feature large hail and damaging winds; though, the tornado risk currently appears slightly elevated (versus Saturday) and a couple tornadoes will be possible. The southern portion of the outlined risk (in purple) across parts of Kansas and Oklahoma will likely feature the greatest tornado risk. Low level and upper level wind shear will be most favorable in this region; whereas areas farther north will be in the more meridional portion of the mid level jet stream (causing veer-back-veer shear profiles).
As the upper level trough continues to close into an upper level low and slowly shift eastward, the severe weather risk will also follow suit.
Today marks the official start of the 2013 Eastern Pacific Hurricane Season. The National Hurricane Center will issue Tropical Weather Outlooks for the region at approximately 4 AM, 10 AM, 4 PM, and 10 PM PST today through November 30th. Special outlooks are issued when conditions warrant. The following list contains the 2013 Pacific storm names. Storm names are recycled every six years, with the exception being those that are retired.
The 2013 Eastern Pacific Hurricane Season is just hours away, and the National Hurricane Center is already monitoring an area for tropical development. A broad area of low pressure has formed roughly 650 miles south of Acapulco, Mexico. At the moment, the low is fairly weak and convection is widespread (disorganized). If further strengthening does occur, it would likely take at least a couple of days before it reaches tropical depression or tropical storm intensity. The NHC has given the low a 30% chance of reaching depression status within 48 hours.
Beyond the next couple of days, the low is unlikely to become a major weather headline, other than perhaps becoming the first system of the season. The odds of intensification into a hurricane appear slim to none as upper level winds look marginally favorable at best. Nearly all guidance, with the exception of the GFS, maintains the low as a relatively weak surface feature through the period. A west to west-northwest motion, with little threat posed to land, is expected at this time.