| February 07 2025 |
Coast to Coast Winter Storm: (2/6/25 - 2/9/25)
By: Josh Weiss, WPC Meteorologist
Meteorological Overview:
A fast moving but potent cross-country storm brought widespread heavy snow and mixed precipitation, including sleet and freezing rain, to the northern tier of the United States during the second week of February. This system began in California on February 6, and moved almost due east across the Great Basin, Northern Rockies, Northern Plains, into the Great Lakes, and finally exited off the New England coast February 9.
The system began as a potent 500mb shortwave trough that was otherwise embedded in the pronounced SW flow just west of California. As this shortwave pivoted northeast, it amplified, and directed an atmospheric river (AR) onshore with impressive integrated vapor transport (IVT) above 500 kg/m/s. This surged anomalous moisture into California, the Great Basin, and the Northern Rockies from Feb 6-7, into which a surface low and right-rear quadrant (RRQ) of a departing upper jet streak produced ascent. As snow levels lowered beneath the advancing trough, widespread moderate to heavy snow spread across the region, peaking on February 7. The heaviest snowfall during the first phase of this event occurred from the Shasta/Siskiyou region of California northeast through eastern Oregon and into Idaho, Montana, and Wyoming. Although the heaviest snow was confined to the higher terrain, generally above 6000 ft, strong ascent due to frontogenesis driven by warm air advection (WAA) led to dynamic cooling of the column, which enhanced Canadian air supplied by a strong high pressure to the north. This resulted in moderate snow accumulations even into the valleys of Oregon, Idaho, and Montana, before the system raced east into the Northern Plains by Feb 8.
During February 8, the shortwave responsible for the heavy snow across the west shifted almost due east, crossing from the Northern Rockies to the Northern Plains and into the Great Lakes. This shortwave remained embedded in otherwise generally zonal flow, leading to its progressive track. While the shortwave remained of modest amplitude, a broad subtropical jet streak arcing across the United States from SW to NE intensified to 150kts, placing favorable diffluence just ahead of the shortwave to enhance deep layer lift, leading to weak surface low pressure development across the Central Plains. As this surface low intensified and advected east, increasing moisture was drawn northward on 285K to 295K isentropic ascent, with the resulting WAA producing a stripe of strong frontogenesis from North Dakota through Wisconsin. This frontogenesis combined with the more broad deep layer synoptic ascent to produce a translating band of heavy snow, resulting in a corridor of heavy snow accumulating at 1-2β/hr across the region. Additionally during this second phase of the storm, the aforementioned WAA pushed an 850mb warm nose above 0C into the Upper MIdwest, causing light freezing rain and sleet accumulations from Iowa to Ohio by late on Feb 8.
With the mid-level flow remaining progressive across much of the country, this system continued to move quickly to the east, impacting the Northeast on Feb 9. As the primary trough raced east across New England, the accompanying modest surface low tracked equally quickly from Ohio to New Jersey. As this wave exited the New Jersey coast, it strengthened more rapidly in response to modestly coupled jet streaks interacting with a baroclinic gradient offshore. While the low continued to progress due east, passing near the 40N/70W benchmark, this intensification helped draw greater moisture northward as intensifying WAA pushed impressive isentropic ascent into New England. This WAA drove a warm nose into southern New England, causing a p-type transition from snow to a mix, leading to significant freezing rain accretions across the Central Appalachians. Farther north, especially in the higher terrain of Upstate NY and central New England, intense 850-700mb frontogenesis on the edge of the warm nose led to a period of very heavy snow, with rates eclipsing 1β/hr at times within a laterally translating snow band that tracked from near Oswego, NY to Portland, ME. The speed of this system limited snowfall from becoming extreme, but impactful snow accumulations occurred beneath this band, with lighter snows encompassing much of the rest of New England. By late on Feb 9 and into Feb 10, the storm and its accompanying forcing pivoted out into the Atlantic, bringing an end to the heavy snow except within lake effect snow bands downstream of Lake Ontario.
Impacts:
This coast-to-coast storm brought significant snow and ice to a large portion of the country, with more than 90 million people affected by winter weather during its lifetime. Snowfall exceeding 6 inches was measured in a nearly continuous swath from California to New England, but the overall speed of the system limited the impacts overall.
The heaviest snowfall occurred in the western United States, especially in the higher terrain. Here, widespread snowfall above 6 inches was measured Feb 6-7, including 17 inches at Teton Village, WY, 14 inches at Palisades Tahoe Ski Area, CA, 12 inches at Lostine, OR, and 10 inches at Horseshoe Bend, ID. Although the heaviest snow was generally above 6000 feet, significant accumulations occurred to as low as 2000 feet, including 9 inches in Billings, MT, 4 inches in Ashland, OR, and 4 inches in Boise, ID. Despite the widespread heavy snow, and moderate snow in the lower terrain, impacts were generally modest across the West.
As the system moved east into the Northern Plains and Great Lakes Feb 7-8, widespread moderate to heavy snow fell from the Dakotas through Michigan, but in a narrow corridor where the translating band of heavy snow occurred. Again, the speed of the system combined with a light/fluffy snow limited significant impacts, but snow accumulating above 6 inches was measured in parts of North Dakota (10.5 inches in Selfridge and 8 inches in Hazleton), South Dakota (9.5 inches in Herried and 6 inches in Lemmon), Minnesota (8 inches in Andover and 5.7 inches in St. Cloud), Wisconsin (13 inches in Medford and 6 inches in Green Bay), and in Michigan (8 inches in Cadillac and 6 inches in Bad Axe). This swath was north of the major urban centers in the area, so only light snow with minimal impacts occurred in Aberdeen, SD, Minneapolis-St. Paul, MN, and Milwaukee, WI.
On the final day of this event, snowfall did intensify across Upstate NY and central New England, where more than 6 inches of snow occurred in Saratoga Springs, NY (9 inches), Landgrove, VT (12.5 inches), Laconia, NH (9.3 inches), Westbrook, ME (11 inches), and Andover, MA (6 inches). Again the major cities of the Northeast were generally spared the worst of this event by being just a bit too far south, although Boston, MA and Albany, NY both received over 4 inches of snow, and Portland, ME picked up over 9 inches. While impacts for the Northeast from this event were also generally modest, this event occurred just 2 days after another snow event brought several inches of a heavier-wet snow, causing more travel delays and additional clean-up immediately following the previous system.
South of the heavy snow axis, mixed precipitation in the form of sleet and freezing rain produced moderate ice accumulations in parts of the Central-Appalachians. This resulted in more than ΒΌβ of ice in parts of PA and MD including Richland and Clymer in PA, as well as Potomac Park and Grantsville in MD. This led to some dangerous and icy roads, especially in the higher terrain of MD and the Laurel Highlands of PA, but roads improved in time for super bowl festivities that Sunday night Feb 9. Lastly, despite most of the major Midwest/Northeast urban areas getting missed or brushed by this system, more than 400 flight cancellations, and 3800 flight delays occurred Feb 8-9 as the large footprint of this significant winter storm impacted air travel across the country.
