U.S. WIND, SCS, FLOOD, WINTER WEATHER An unusually strong winter storm crossing the Central Plains continues to bring winter weather, strong winds, heavy precipitation and severe thunderstorms to areas of the Central U.S. and South-Central Canada. The storm, unofficially named "Ulmer" by the Weather Channel continues to bring heavy snowfall with strong and potentially damaging winds, reduced visibility and potential blizzard conditions from the Central Plains into South-Central Canada today. Ongoing transportation disruption is probable along with downed trees and powerlines and some property damage. The storm has caused extensive transportation disruption for areas including Colorado, Wyoming, Nebraska and the Dakotas, with closure of major interstates including I-25, I-70, I-80, I-90 and I-76 in certain areas. Media reports indicate over 1,100 motorists stranded in Colorado due to conditions, along with closure of all runways at Denver International Airport yesterday. Significant power outages have been reported, especially in Colorado and Nebraska. Some property and vehicle damage has also been reported due to significant wind gusts. Meanwhile for portions of the Upper Mississippi Valley and Central Great Lakes, heavy rainfall brings a considerable threat for flooding and flash flooding, due to rainwater combined with the snowpack, warming temperatures and frozen ground. Ice dams will also amplify the flood threat for affected river systems. The combined weight of the snowpack together with rainwater also amplifies the threat of roof collapse in certain areas. Heavy rainfall will also maintain the flood threat for the Central and Lower Mississippi Valley and adjacent watersheds. Meanwhile from the Northern Gulf to the Lower Great Lakes, a threat for severe thunderstorms includes an enhanced risk flagged by the U.S. Storm Prediction Center (SPC). Damaging nontornadic wind gusts are the key threat expected by the SPC along with hail and tornadoes. Severe thunderstorms yesterday produced SPC reports of damaging nontornadic wind gusts, primarily from East Texas to Northern Mississippi. The storm was enabled by a strong upper-level system with robust upper-air support and moisture. This produced a strong surface low that reached a minimum pressure of 968 mb yesterday afternoon while over Southeast Colorado, after dropping more than 24 mb in 24 hours as a case of "bomb cyclogenesis". The resulting pressure gradient around this low maintains a significant wind threat.
Meanwhile the upper-air mechanics together with abundant moisture maintain a threat for heavy precipitation. The system also continues to produce a threat for severe thunderstorms on the warm side of the system, from the Northern Gulf to the Lower Great Lakes. Wind gusts in excess of 70 mph have been observed in Wyoming, Utah, West Texas, Oklahoma, New Mexico, Nevada, Nebraska, Kansas and Colorado. Wind gusts approaching or even surpassing 100 mph have been observed in Colorado, New Mexico and West Texas. Snowfall amounts of 12 inches or more have been reported in New Mexico, Utah, Wyoming, South Dakota, North Dakota, and especially Colorado. Specifics can be found at the WPC summary. The U.S. National Weather Service (NWS) and the Meteorological Service of Canada (MSC) have issued watches, warnings and statements for areas under potential or imminent threat, and these will be updated as the situation evolves. Official watches and warnings, and statements from emergency management agencies supersede this update, and should be closely followed concerning matters of personal safety. Local watches and warnings can be found at weather.gov for U.S. locations, and at weather.gc.ca for locations in Canada. For further details affecting your area of responsibility, please contact me. Severe Thunderstorm Outlook - Today Orange - Enhanced Risk for Severe Thunderstorms Yellow - Slight Risk for Severe Thunderstorms Dark Green - Marginal Risk for Severe Thunderstorms Light Green - General Risk for Thunderstorms SOURCE: NOAA/SPC
National Forecast Chart - Today National Forecast Chart - Tomorrow
Interpolated Observed Snowfall Amounts 48 Hours Ending 8AM EDT (12 UTC) Thursday March 14 SOURCE: NOAA/NOHRSC Forecast Precipitation Amounts (liquid or liquid equivalent) 24 Hours Ending 8AM EDT (12 UTC) Friday March 15
Significant River Flood Outlook - March 14-19 Severe Thunderstorm Reports Yesterday SOURCE: NOAA/SPC
James Waller,PhD Research Meteorlogist 215-864-3622 (Desk) 215-964-5879 (Mobile) james.waller@guycarp.com Guy Carpenter & Company LLC Guy Carpenter & Company, LLC provides this report for general information only. The information contained herein is based on sources we believe reliable, but we do not guarantee its accuracy, and it should be understood to be general insurance/reinsurance information only. Guy Carpenter & Company, LLC makes no representations or warranties, express or implied. The information is not intended to be taken as advice with respect to any individual situation and cannot be relied upon as such. Please consult your insurance/reinsurance advisors with respect to individual coverage issues. Readers are cautioned not to place undue reliance on any historical, current or forward-looking statements. Guy Carpenter & Company, LLC undertakes no obligation to update or revise publicly any historical, current or forward-looking statements, whether as a result of new information, research, future events or otherwise. This document or any portion of the information it contains may not be copied or reproduced in any form without the permission of Guy Carpenter & Company, LLC, except that clients of Guy Carpenter & Company, LLC need not obtain such permission when using this report for their internal purposes. The trademarks and service marks contained herein are the property of their respective owners. MARSH GUY CARPENTER MERCER OLIVER WYMAN Guy Carpenter 1166 Avenue of the Americas, New York, NY, 10036 USA