Hurricane Sandra Heads for Mexican Coast; Icing, Flooding Hit Southern Plains

After becoming the latest major hurricane on record in the Western Hemisphere, a weakening Hurricane Sandra remained on track Friday for a history-making landfall early Saturday on the coast of Mexico’s Sinaloa state. A Tropical Storm Warning was in effect for Las Islas Marias and for Mexico’s Pacific coast from Altata to San Blas, including the Mazatlan area. Sandra will be a fast-decaying storm by that point, but even in that condition, it should be a record-setter: no tropical cyclone on record has made landfall so late in the year on either the Atlantic or Pacific coast of Mexico. The current record-holder is Tara (Nov. 12, 1961).


Figure 1. Enhanced infrared satellite image of Hurricane Sandra as of 10:37 am EST Friday, November 27, 2015.

Sandra peaked at Category 4 strength early on Thanksgiving Day (November 26), with top sustained winds briefly hitting an eye-popping 145 mph. The previous record-latest major hurricane in the Western Hemisphere was an unnamed Atlantic hurricane in 1934 that held on to Category 3 status until 00 UTC November 24. Sandra is also now the latest Category 4 storm ever observed in either the Eastern Pacific (previous record: Hurricane Kenneth on November 22, 2011) or the Atlantic (previous record: "Wrong Way" Lenny on November 18, 1999.) Sandra’s peak winds had decreased to 85 knots (100 mph) by the time of the 11 AM EST Friday advisory from the National Hurricane Center. Wind shear has picked up dramatically over Sandra’s track, giving the storm a comma shape more akin to a hybrid or subtropical cyclone (see Figure 1), but Sandra has managed to maintain a small, intense convective core while picking up forward speed. Well before landfall, the strong shear is expected to push Sandra’s mid-level circulation ahead of its low-level center, hastening the storm’s demise.


Figure 2. Multisensor-observed precipitation for the 24-hour period ending at 6:00 am CST Friday, November 27, 2015. Image credit: NWS Advanced Hydrologic Prediction Service.

Record Thanksgiving Day rains--and more to come
A sprawling upper-level low in the southwest U.S. teamed up with unusually rich Gulf moisture (record amounts for the time of year in some locations) to make for a very soggy Thanksgiving over much of the central U.S. Factoring in the various year-to-year dates of Thanksgiving Day, Thursday qualified as the wettest Thanksgiving Day on record by an ample margin for several cities with century-plus periods of record, including:

Wichita, KS (1.66”, old record 0.81” in 1977)
Milwaukee, WI (1.55”, old record 0.98” in 1968)
Madison, WI (1.19”, old record 1.06” in 1879)
Rockford, IL (1.51”, old record 0.81” in 1918)
Kansas City, MO (1.61”, old record 1.19” in 1896)
[Thanks to Michael Butler, The Weather Channel, for these statistics]

Some of the heaviest rains struck the Dallas-Fort Worth area, where at least two motorists were killed in overnight flooding. The year 2015 is now officially the wettest on record for the nation’s fourth largest metropolitan area. From Thursday afternoon through 8:53 AM CST Friday, the Dallas/Fort Worth Metropolitan Airport received 4.51” of rain, pushing their year-to-date total to 55.26” with five weeks still left in the year. The previous annual record was 53.54,” set in 1991. Weather records in the DFW area began at downtown Fort Worth in 1898. A few localized areas in southeast Oklahoma and east Texas have racked up more than 70” of rain this year, with more than 80” in places between Houston and Beaumont. Baytown picked up 90.21” from January through October, notching more than 5” in every month except February.

Moisture and energy from Hurricane Sandra will be flowing over Texas this weekend, adding to the multiday deluge now under way. Various flood and flash flood watches and warnings are in effect from north Texas to southwest Illinois, with Arkansas in line for especially heavy rain falling over rugged, flood-prone terrain. Further northwest, ice storm warnings remain in effect from far eastern New Mexico to parts of south central Kansas, with ice accumulations of more than half an inch possible in some areas. Some roadway icing is expected, but with air temperatures staying close to freezing in many areas, the biggest hazard of this prolonged event may be from ice-encrusted tree limbs and power lines.

Whether or not you’re traveling this weekend, take care and stay safe!

Bob Henson and Jeff Masters