Weather Briefing January 30, 2015 National Weather Service Detroit/Pontiac, MI

Decision Support Briefing Highlights Event Potential for Accumulating Snow Sunday. Highest Totals Expected Along and South of a Detroit to Ann Arbor Line. Winter Storm Watch For Lenawee/Monroe/Washtenaw/ and Wayne Counties Late Saturday Night through Late Sunday Night Low Pressure Will Move East Across the Ohio Valley, with Heavy Snow Falling to the North of the Storm Track Surface Map For Sunday Feb 1st

Decision Support Briefing Highlights Event Summary 6-10” of Snow and Gusty Winds Winter Storm Watch in Effect Friday and into Saturday All of Southeast Michigan Forecast for Friday (24 hrs)

Decision Support Briefing Highlights Event Summary 6-10” of Snow and Gusty Winds Winter Storm Watch in Effect Friday and into Saturday All of Southeast Michigan Forecast for Friday (36 hrs)

Decision Support Briefing Highlights Event Summary 6-10” of Snow and Gusty Winds Winter Storm Watch in Effect Friday and into Saturday All of Southeast Michigan Forecast for Friday (48 hrs)

Winter Hazard Risk Assessment ExtremeHigh Moderate Low Little Disruption to Daily Life Rarely Directly Life Threatening Recovery Time Around When Weather Hazard Ends This Event is a Common Event Extreme: - Historic Weather Hazard/Event - Life Threatening - Total disruption of daily life - Recovery Time: days to one week High: - Rare Weather Hazard/Event - Potentially Life Threatening - Widespread disruption of daily life - Recovery Time: hours to a day Moderate: - Occasional Weather Hazard/Event - Rarely directly life threatening - Some disruption of daily life - Recovery Time: +/- 6 hrs of when weather ends

Winter Hazard Risk Assessment ExtremeHigh Moderate Low Some Disruption to Daily Life Rarely Directly Life Threatening Recovery Time +/- 6 Hours of When Weather Hazard Ends This Event is an Occasional Weather Event Extreme: - Historic Weather Hazard/Event - Life Threatening - Total disruption of daily life - Recovery Time: days to one week High: - Rare Weather Hazard/Event - Potentially Life Threatening - Widespread disruption of daily life - Recovery Time: hours to a day Moderate: - Occasional Weather Hazard/Event - Rarely directly life threatening - Some disruption of daily life - Recovery Time: +/- 6 hrs of when weather ends

Winter Watch Hazard Risk Assessment ExtremeHigh Moderate Low Potential to Cause Disruption to Daily Life Recovery Time Around When Weather Hazard Ends to around a Day This Potential Event is an Occasional to Rare Weather Event Extreme: - Historic Weather Hazard/Event - Life Threatening - Total disruption of daily life - Recovery Time: days to one week High: - Rare Weather Hazard/Event - Potentially Life Threatening - Widespread disruption of daily life - Recovery Time: hours to a day Moderate: - Occasional Weather Hazard/Event - Rarely directly life threatening - Some disruption of daily life - Recovery Time: +/- 6 hrs of when weather ends

Winter Hazard Risk Assessment ExtremeHigh Moderate Low Some Disruption to Daily Life Rarely Directly Life Threatening Recovery Time +/- 6 hrs After the Weather Ends This Event is an Occasional Weather Event Extreme: - Historic Weather Hazard/Event - Life Threatening - Total disruption of daily life - Recovery Time: days to one week High: - Rare Weather Hazard/Event - Potentially Life Threatening - Widespread disruption of daily life - Recovery Time: hours to a day Moderate: - Occasional Weather Hazard/Event - Rarely directly life threatening - Some disruption of daily life - Recovery Time: +/- 6 hrs of when weather ends

Winter Watch Hazard Risk Assessment ExtremeHigh Moderate Low Potential to Cause Total Disruption to Daily Life Potentially Life Threatening Recovery Time Several Hours to One Week This Potential Event is a Rare to Historic Weather Event Extreme: - Historic Weather Hazard/Event - Life Threatening - Total disruption of daily life - Recovery Time: days to one week High: - Rare Weather Hazard/Event - Potentially Life Threatening - Widespread disruption of daily life - Recovery Time: hours to a day Moderate: - Occasional Weather Hazard/Event - Rarely directly life threatening - Some disruption of daily life - Recovery Time: +/- 6 hrs of when weather ends

Winter Hazard Risk Assessment ExtremeHigh Moderate Low Total Disruption of Daily Life Life Threatening Recovery Time Days to One Week After Weather Ends This Event is an Historic Weather Event Extreme: - Historic Weather Hazard/Event - Life Threatening - Total disruption of daily life - Recovery Time: days to one week High: - Rare Weather Hazard/Event - Potentially Life Threatening - Widespread disruption of daily life - Recovery Time: hours to a day Moderate: - Occasional Weather Hazard/Event - Rarely directly life threatening - Some disruption of daily life - Recovery Time: +/- 6 hrs of when weather ends

Power Outage Potential HighMediumLow Blowing/Drifting Potential HighMediumLow Potential Impacts Road Conditions Slippery road conditions expected in heavy snow Temperatures will hold in the upper teens and low 20s Northeast winds 10 to 20 MPH Additional Potential Impacts Travel may be severely restricted This may be a long duration event (greater than 18 hours in duration)

Timing of Winter Weather Beginning Snow will begin late Saturday night, mainly south of the I-94 corridor. The snow will expand north during the day Sunday. Heaviest Heaviest snow is expected Sunday Afternoon and early Evening. Ending Snow will end after midnight Sunday Night.

AREA View High confidence snowfall totals will exceed 4 inches. Moderate to High confidence snowfall totals will exceed 6 inches Snowfall Confidence Total Snowfall Late Sat Night – Sun Night

AREA View Low to Medium confidence snowfall totals will exceed 8 inches. Snowfall Confidence Total Snowfall Late Sat Night – Sun Night

Storm Total Snowfall Forecast Totals For Sunday/Sun Night Type of Snow Mix of Heavy Wet and Light and Fluffy Snow Accumulation 6 inches or more south of I-94 4 to 6 inches between I-94 and M-59 2 to 4 inches between M-59 and I-69 Less than 2 inches north of I-69 Additional Hazards Some blowing and drifting of snow Wind chills below zero Sunday evening and Sunday Night Storm Total Snow From Midnight Sat Night through 7 AM Monday

Forecast Challenges There remains uncertainty as to how far north this storm system will track. There remains uncertainty as to how far north this storm system will track. If it tracks farther north, snowfall accumulations north of the I-94 corridor will be much higher. If it tracks farther north, snowfall accumulations north of the I-94 corridor will be much higher. If however, the system tracks farther south, snowfall accumulations will be lower than forecast. If however, the system tracks farther south, snowfall accumulations will be lower than forecast. There is some uncertainty as to how quickly the heavy snow overspreads the area on Sunday. There is some uncertainty as to how quickly the heavy snow overspreads the area on Sunday.

Decision Support Briefing Summary WhatWhereTimingImpacts Snow 8-10 inches Nebraska (North of I-80) 7 PM – 7 AMSnow-packed roadways North Wind mph Nebraska (North of I-80) 12 AM – 7 AM Reduced Visibilities Snow drifts possible on East-West roads Temperatures Highs: o F Lows: -10 to -5 o F East NebraskaTuesday - Thursday Frost Bite Hypothermia Freezing of Exposed Pipes

Additional Information NWS Detroit/Pontiac, MI Local Hazards Page Great Lakes Marine Portal