Tropical Storms, Tornadoes, a Cat 5 Typhoon, and a Blizzard, Oh My!

Meteorological Mother's Day Madness is at hand. The strongest tropical storm ever to make landfall in the U.S. so early in the year hit South Carolina this morning, at the same time as a Category 5 super typhoon hit the Philippines, a raging blizzard pounded South Dakota, and the U.S. Plains cleaned up from an onslaught of 45 tornadoes the previous day. Let's start today's post with Tropical Storm Ana, which made landfall at 6:15 am EDT on the coast of South Carolina just south of the North Carolina border. At landfall, Ana had top winds of 45 mph, making the the strongest tropical storm ever recorded to hit the U.S. so early in the year. Ana brought peak winds of 47 mph, gusting to 58 mph, at 9:50 pm EDT Saturday to the Frying Pan Shoals Buoy 41013, located off the coast of North Carolina. North Myrtle Beach, SC recorded a gust of 49.5 mph at 12:53 am this morning. Ana is expected to bring 2 - 4" of rain to portions of coastal South Carolina and North Carolina though Monday.


Figure 1. MODIS satellite image of Tropical Storm Ana taken near 3 pm EDT May 9, 2015. At the time, Ana had top winds of 60 mph. Image credit: NASA Worldview.


Figure 2. Radar image of Ana taken at 6:15 am EDT Sunday May 10, 2015, from Wilmington, North Carolina. Ana was making landfall near Myrtle Beach, South Carolina.

How unusual is a May landfall?
Named storms that make landfall in the U.S. before the June 1 start of hurricane season are rare; between 1900 - 2014 there were only nine such landfalls, an average of one every thirteen years. The only U.S. landfall on record that occurred earlier than Ana's was on February 3, 1952, when the Groundhog Day tropical storm, packing winds of 40 mph, struck near Cape Sable, Florida. Eight U.S. landfalls have occurred in May, with Beryl the strongest of the group in recent years, packing 65-mph winds during its landfall near Jacksonville Beach, Florida, on May 28, 2012 (note, though, that a 2013 paper in the Bulletin of the American Meteorological Society documented a hurricane landfall on the Florida Panhandle on May 28, 1863, with estimated peak winds of 105 mph.)

Here is the full list of peak winds observed on U.S. shores from named systems before June 1 since 1900, including both landfalling and offshore systems, as compiled by tropical meteorologist Andrew Hagen (StormGeo) using the HURDAT database. These are ranked in descending order of observed winds and listed with the state(s) where the winds were recorded.

5/28/2012 – 55 kt – FL (Beryl)
5/29/1908 – 55 kt – NC
5/27/1972 – 50 kt – GA (Alpha)
5/10/2015 – 40 kt – NC (Ana)
5/23/1976 – 40 kt – FL/GA (unnamed)
5/30/1959 – 40 kt – LA (Arlene)
2/3/1952 – 35 kt – FL (Groundhog Day Storm)
5/10/2007 – 35 kt – GA (Andrea)
5/14/1916 – 35 kt – FL
5/17/1951 – 35 kt – FL (Able)


Figure 3. Super Typhoon Noul as seen by the new Japanese Himawari-8 satellite at 00:50 UTC May 10, 2015. At the time, Noul was a Category 5 storm with 160 mph winds. The University of Wisconsin/CIMSS has put together a remarkable hi-res satellite animation of the storm from the Himawari-8 satellite (which is still in check-out mode.) This is the most advanced geostationary satellite ever launched, and has images available every ten minutes with a resolution four times higher than the U.S. GOES satellites. The Himawari-8 imager is a clone of the imager expected to be launched on the U.S. GOES-R satellite in March 2016, which is likely to be initially positioned to view the Western Atlantic and Eastern Pacific. Something to look forward to!

Category 5 Super Typhoon Noul hits the Philippines
Category 5 Super Typhoon Noul (called Dodong in the Philippines’ naming system) made landfall near 5 am EDT Sunday, May 10, on the extreme northeastern tip of the Philippines' Luzon Island at Pananapan Pt., Sta. Ana, Cagayan. Satellite loops on Sunday morning showed that Noul's encounter with land significantly weakened the storm, with the eye disappearing from view and the storm's heavy thunderstorm activity noticeably deteriorating. Storm chaser James Reynolds has commentary and video of the landfall at his Twitter feed. Thankfully, the northeastern portion of the Philippines is sparsely populated, so Noul is not likely to be a major disaster for the Philippines. Noul is caught in a trough of low pressure that will swing the storm to the north and northeast, out to sea, skirting the coast of Japan.

An unusually early and violent typhoon season
May 10 is exceptionally early to be getting a Category 5 storm in the Northwest Pacific, let alone one landfalling at that strength! At its peak on Sunday morning, the Japan Meteorological Agency put Noul's central pressure at 915 mb. This makes Noul is the third strongest typhoon on record for so early in the year. The only stronger ones were Super Typhoon Amy of 1971, which deepened to 890 mb on May 2, and Super Typhoon Iris of 1951, which hit 909 mb on May 3.

Super Typhoon Noul is already the second Category Five storm this year in the Northwest Pacific, and the fourth overall on Earth in 2015. This is an unusually large number of these high-end tropical cyclones for so early in the year; Earth averaged just 4.6 Category 5 storms per year between 1990 - 2014, with the majority of these storms occurring during the August - November peak of the Northern Hemisphere's tropical cyclone season; 59% of all Cat 5s occur in the Northwest Pacific. Noul's formation date of May 3 was the 2nd earliest appearance of the season's 6th named storm on record for the Northwest Pacific. The Japan Meteorological Agency (JMA) just began issuing advisories for Tropical Storm Dolphin in Micronesia on May 9, breaking the record set on May 19, 1971 for the earliest formation of the Northwest Pacific's seventh named storm of the year, according to statistics of the Japan Meteorological Agency's database from 1951 - 2015 maintained by Digital Typhoon. The early and violent start to 2015 typhoon season is due, in part, to exceptionally warm ocean temperatures in the typhoon breeding region between 5 - 10°N near the Date Line. These temperatures have been over 2°C (3.6°F) above average in recent months, due to a strengthening El Niño event.

The other three Category 5 storms of 2015 were Super Typhoon Maysak of March (160 mph winds), one of only three Category 5 typhoons ever observed in the Northwest Pacific prior to April; Tropical Cyclone Pam (165 mph winds), which devastated Vanuatu in mid-March, and Tropical Cyclone Eunice (160 mph winds), which affected ocean areas in the South Indian Ocean. Reliable satellite records of Southern Hemisphere tropical cyclones extend back to the early 1990s, so we only have about a 25-year period of good records for global Category 5 tropical cyclones.


Figure 4. Radar image of the supercell thunderstorm that hit Cisco, Texas on Saturday night, killing one person and injuring three.

Multiday severe outbreak shifts to eastern Plains
Storm-hammered residents of Oklahoma and Texas will get a chance to catch their breath early this week, as the intense weather plaguing the area since Wednesday finally moves eastward. The next significant episode is likely to arrive in the Southern Plains around next weekend, possibly preceded by yet another batch of heavy-raining storms later this week. In the meantime, severe storms will cover an expanded region on Sunday, with a slight risk extending from southern Minnesota to Illinois to central Texas, as a strong upper low accelerates eastward from Colorado. In its 1:00 am CDT outlook, the NOAA Storm Prediction Center called for an enhanced risk on Sunday in two areas, one centered on western Iowa (near the surface low and warm front) and another on northeast Texas (where the trailing end of the cold front will encounter especially rich low-level moisture). The highest risk of tornadoes will be in these two areas, although a widespread outbreak of strong tornadoes is not expected. Sunday's severe weather got off to an early start, though, with three tornado watches already in effect by 11:15 am CDT and law enforcement reporting damage from a tornado that struck near Delmar, SD, around 10:30 am CDT.

Saturday's severe weather was also split into two main focal points. Toward the south, a fearsome supercell churned just south of Interstate 20 from east of Abilene, TX, to the southwest exurbs of Dallas-Fort Worth. At least one person was killed by a tornado near the town of Cisco (see Figure 1) that appears to have produced significant damage. Although the storm later produced another tornado near Stephenville, it fortunately failed to live up to the potential implied by a very strong and persistent rotation signature on Doppler radar. Another supercell about 100 miles to the north generated twisters near Burkburnett, TX, and Randlett, OK, and a brief tornado was also reported near Elk City, OK. The other center of action for tornadoes was across eastern Colorado and western Kansas, where several storms were prolific twister-producers. Strong winds and cold air associated with the upper low more than compensated for cool surface temperatures (mainly in the 60s F), producing a very favorable setup for multiple high-plains tornadoes. An isolated supercell moving north from Eads, CO, produced at least six tornadoes across largely unpopulated terrain, and more than a dozen tornado reports came in from a late-evening storm that crossed I-70 in far northwest Kansas. Several more tornadoes were spun out by another cell just to the east (see Figure 5 below).


Figure 5. One of several tornadoes that emerged from a supercell near Collyer, KS. Image credit: wunderphotographer mhaase7.

Just a couple hours' drive northwest of the Colorado twisters, the scene was decidedly more wintry by evening. A burst of heavy snow swept across the Denver metro area around sunset, causing numerous accidents as temperatures fell into the upper 20s. The snow was preceded by heavy rain that put much of Colorado in flash flood watches and warnings. At one point, Colorado Springs was under five different types of NWS alerts, as noted by the Denver Post. The snow extended into Colorado's northern mountains, western Nebraska, eastern Wyoming, and north to the Black Hills of South Dakota, where blizzard warnings were in effect on Saturday night. Snowfall in May isn't all that uncommon in these parts--Denver averages 1.7 inches for the month--but this weekend's onslaught in Rapid City was another in a string of noteworthy snows falling either very early or very late in the season. These include the all-time multiday record storm of April 8-10, 2013 (28.2"); the devastating snowstorm of October 3-5, 2013 (23.1"); and the city's earliest snowfall on record (1.6" on September 11, 2014).

We're again covering today's severe weather on the experimental WU live blog.

Jeff Masters (tropical) and Bob Henson (severe)


Figure 6. The late-evening light of May illuminates snow falling on Saturday in Minatare, Nebraska, just southeast of Scottsbluff. Image credit: wunderphotographer JdyJdyJdy.