Winter Storm Ulmer 'Bombs' Out, Becomes 'Bomb Cyclone' , Smashing Pressure Records

Meteorologists refer to a strengthening low as "bombing" out or undergoing bombogenesis if its minimum surface pressure drops by at least 24 millibars in 24 hours or less.

(IMAGES: The Bomb Cyclone as it Intensified)

In Winter Storm Ulmer's case, its central pressure dropped from 994 millibars around 8 p.m. MDT Tuesday night, March 12, estimated by NOAA Weather Prediction Center meteorologist David Roth, to 970 millibars at 9 a.m. MDT Wednesday, March 13, meeting bombogenesis criteria in just over half the time.

This bomb cyclone tied or set preliminary, unofficial all-time low-pressure records in four locations.

Pueblo, Colorado, set its preliminary, unofficial all-time record-low pressure early Wednesday morning, March 13, according to the National Weather Service. Colorado state climatologist Russ Schumacher tweeted it was the lowest pressure on record there since at least 1950.

Roth, who tracks U.S. pressure records, also noted low-pressure records were tied in Alamosa, Colorado, broken in Lamar, Colorado, and Clayton, New Mexico.

The NWS tweeted the pressure in Lamar, Colorado, may have set an all-time state record, pending further investigation.

The atmospheric pressure in Dodge City, Kansas, dipped to its lowest level in over 100 years Wednesday afternoon, March 13, according to the local NWS office. A pressure of 974.7 millibars was measured there, which broke the modern-day record of 974.9 millibars set in 1960, but was short of the all-time record-low pressure of 971.6 millibars set in 1878 and short of the known state record.

The storm bottomed out at 968 millibars on the afternoon of March 13 near Manter, Kansas, according to NOAA's Weather Prediction Center.

Meteorologists frequently discuss pressure in terms of millibars, rather than inches of mercury. The lower the pressure in a storm, the more intense it is.

And the greater difference in pressure over an area, the stronger the winds.

How This Compares With Other Intense Lows

Roth's database found that this storm may have the lowest pressure in modern records in parts of southern and central Kansas since Feb. 9, 1960.

For parts of southeastern Colorado, northern Kansas into central and eastern Nebraska and southern South Dakota, the modern-day record-low pressure was on March 26, 1950. Surface pressure in parts of Nebraska and South Dakota bottomed out in the 960s millibars.

That three-day storm brought 34 inches of snow in just 24 hours in the Black Hills of South Dakota, according to weather historian David Ludlum.

More recently, the so-called Octobomb storm in 2010 set all-time low-pressure records in the northern Plains and upper Midwest, including most of Minnesota, western Wisconsin, parts of the eastern Dakotas and western Upper Michigan.

Pressure during that storm plunged to the 950s millibars in northern Minnesota, narrowly missing the all-time official U.S. low-pressure record not from a tropical cyclone: 955 millibars in Block Island, Rhode Island, on March 7, 1932, and also in Canton, New York, on Jan. 13, 1913.

(WUNDERBLOG: All-Time Pressure Records)

This storm didn't bring much snow, but produced at least 60 mph wind gusts in nine states from the Dakotas and Nebraska to Michigan and also spawned a rash of severe thunderstorms with damaging winds and tornadoes in the Ohio Valley, Tennessee Valley and piedmont of the Carolinas.

These intense storms can happen in the northern Plains and western Great Lakes in fall. The infamous November 1975 storm which sank the freighter the Edmund Fitzgerald was followed 23 years later to the day by a second, stronger storm, which later the Octobomb surpassed, pressure-wise.

The corridor off the East Coast of the U.S. is notorious for these type of bombogenesis events, particularly in recent years.

In early-March 2018, the first of the so-called four-easters, Winter Storm Riley, bombed out off the East Coast, dropping to a pressure comparable to what we may see with this Plains storm, driving destructive coastal flooding to parts of the Eastern Seaboard.

Two months prior to that in early-January 2018, Winter Storm Grayson intensified at the most rapid rate on record for the western Atlantic Ocean, plunging roughly 59 millibars in 24 hours to a low of 950 millibars.