Threat LegendOrange – Strong to Severe Thunderstorms PossibleRed – Significant Severe Thunderstorm ThreatPurple – Severe Weather Outbreak (Day 1 and 2 Only)Green – Excessive Rainfall

Blue – Significant Snow/Ice

Day 1 Threat Regions Map Day 2 Threat Regions Map

WDT HAZARDOUS WEATHER OUTLOOK 3/1/2017

Days 1 – 2 (Short Term) Threat Summary

DAY 1TENNESSEE VALLEY INTO OHIO VALLEY: SEVERE THUNDERSTORMS LIKELY

EASTERN UNITED STATES: STRONG TO SEVERE THUNDERSTORMS POSSIBLE

DAY 2 NO THREAT REGIONS

Day 3

Day 6

WDT THREATS AT A GLANCE – Days 3 Through 7 3/1/2017

Day 4

Day 5

Threat LegendOrange – Strong to Severe Thunderstorms PossibleRed – Significant Severe Thunderstorm ThreatPurple – Severe Weather Outbreak (Day 1 and 2 Only)Green – Excessive Rainfall

Blue – Significant Snow/Ice

Day 7

Threat LegendOrange – Strong to Severe Thunderstorms PossibleRed – Significant Severe Thunderstorm ThreatPurple – Severe Weather Outbreak (Day 1 and 2 Only)Green – Excessive Rainfall

Blue – Significant Snow/Ice

Day 1 – Wednesday Threat Assessments and Morning Frontal Analysis Threat Regions Discussion:

Eastern United States: With a large upper level tough progressing to the east along with astrong cold front extending southward across the eastern United States, strong to severethunderstorms are forecast ahead and along the cold front. In the Northeast, ongoing convection and thunderstorm into the morning could lead to lingering strong to severe thunderstorms in the morning. Into the afternoon, additional thunderstorm development may be possible along the cold front. Further south into the Southeast, limited moisture will decrease overall thunderstorm potential ahead of the cold front, although an isolated thunderstorm may develop with strong wind gusts as the main potential. In addition to the developing thunderstorms ahead of the cold front, additional thunderstorms are forecast along the front with the storms potentially strong to severe.

Tennessee Valley into Ohio Valley: Across the Tennessee Valley and into the Ohio Valley will be the region with the highest severe weather potential on Wednesday. During the morning hours, an ongoing line of strong to severe thunderstorms is forecast to move through the region. Into the afternoon, recovery of the atmosphere is expected despite theearly thunderstorms. Relatively high dewpoints will lead to building instability with isolated thunderstorm development likely. With the strong low level shear in place, thunderstorms are expected to become supercells with strong updraft potential. This will lead to the potential for large hail, tornadoes, damaging wind gusts, frequent lightning, and heavy rainfall possible with the thunderstorms into the afternoon hours.

Threat LegendOrange – Strong to Severe Thunderstorms PossibleRed – Significant Severe Thunderstorm ThreatPurple – Severe Weather Outbreak (Day 1 and 2 Only)Green – Excessive Rainfall

Blue – Significant Snow/Ice

Day 2 – Thursday Threat Assessments and Morning Frontal Analysis No threat regions:

Into Thursday, the cold front across the east coast is forecast to push offshore with some lingering rain showers possible, especially over Florida as the front will move through during the morning. In the wake of the front, a weak low pressure system will move acrossthe Great Lakes with some snow flurries while high pressure is expected to the south and over the Mountain West.

Threat LegendOrange – Strong to Severe Thunderstorms PossibleRed – Significant Severe Thunderstorm ThreatPurple – Severe Weather Outbreak (Day 1 and 2 Only)Green – Excessive Rainfall

Blue – Significant Snow/Ice

Day 3 – Friday Threat Assessments and Morning Frontal Analysis No threat regions:

The weak area of low pressure across the Great Lakes will move into the Northeast bringingsnow showers in the region. High pressure is expected to shift further east while the nextlow pressure system develops across the western United States.

Threat LegendOrange – Strong to Severe Thunderstorms PossibleRed – Significant Severe Thunderstorm ThreatPurple – Severe Weather Outbreak (Day 1 and 2 Only)Green – Excessive Rainfall

Blue – Significant Snow/Ice

Day 4 – Saturday Threat Assessments and Morning Frontal Analysis Threat Regions Discussion:

Intermountain Northwest: Ahead of the cold front moving onshore, heavy snowfall is forecast to increase on Saturday within the higher elevations across the Northwest. Total snowfall accumulation of 8 to 12 inches will be possible with locally higher amounts in excess of 16 inches.

Threat LegendOrange – Strong to Severe Thunderstorms PossibleRed – Significant Severe Thunderstorm ThreatPurple – Severe Weather Outbreak (Day 1 and 2 Only)Green – Excessive Rainfall

Blue – Significant Snow/Ice

Day 5 – Sunday Threat Assessments and Morning Frontal Analysis Threat Regions Discussion:

Intermountain Northwest: Heavy snowfall is forecast to continue in the Northwest, with the heavy snowfall in the higher elevations shifting further south into the Sierra Nevadas as the low pressure center shifts slightly further south off the coast. With the low remaining off the coast, the potential for additional snowfall will be possible with total accumulations greater than 8 inches. Locally higher amounts, especially on the peaks, of greater than 16 inches will be possible.

Day 6 – Monday Threat Assessments and Morning Frontal Analysis

Discussion: On Monday, with southerly flow in place over the weekend and continued southerly flow from the Gulf of Mexico, moisture return will be possible across the Southern Plains andinto the Midwest. Along with the moisture return, a cold front is forecast to extend southward with a large, fast-moving upper level trough to quickly move through the region. As a result, the chance of strong to severe thunderstorms will be present on Monday with thunderstorms evolving into a squall line over time based upon this model run. Please note there remains some variability is the mid-range forecast at this time. As a result, the threat of strong to severe thunderstorms could change in the upcoming days. WeatherOps will continue to monitor the development of the moisture return and low pressure system closely in the upcoming days.

Day 7 – Tuesday Threat Assessments and Morning Frontal Analysis