Forecast and Severe Outlook: Wednesday, May 11th

Additional severe weather is in the forecast as the last several days have brought 67 tornadoes from Colorado to Kentucky.  Strong low pressure moving into Canada will continue to move a strong warm front North ahead of a weaker cold front.   This clash of frontal boundaries is responsible for the weather the Plains and river valleys have been dealing with.

The current Surface Analysis

Surface map us

Today’s National Forecast

Weather Forecast map

The main weather feature across the nation will be a strong low pressure system over the north-central U.S. that will have a trailing cold front extending southward to Texas and the Desert Southwest. An occluded surface low over North Dakota will slowly lift northeastward to southern Canada, with rainy weather over eastern Montana and western North Dakota for the first half of Wednesday. Farther to the south, another surface low along the trailing cold front will also produce widespread showers and thunderstorms extending from Texas to the Ohio Valley. Some of these storms could be severe at times, and also produce localized flash flooding.

Temperatures are expected to be below normal across much of the Intermountain West with an upper level trough in place, and also for the Northeast U.S. which will be under the influence of a Canadian surface high. It will continue to be warm and humid south of a stationary frontal boundary, which will extend from the Ohio Valley eastward to the Mid-Atlantic coast. Highs in the 80s to near 90 along with noticeable humidity will be commonplace across the Deep South and the Southeast states.

West of the Rocky Mountains, a quiet weather pattern should prevail through the end of the week with no Pacific storm systems imminent. Inland temperatures should slowly return closer to average after the recent cool weather.

Current Severe Weather Outlook

Fire Weather Update

Fire Weather

No critical Fire areas to report.

Severe Weather Analysis

Summary

Scattered severe storms are forecast from parts of North Texas into Oklahoma and the Missouri and Mississippi River Valleys. Large hail and damaging winds will be the main concern by late in the day but a brief tornado or 2 are possible for this region.  For the Ohio Valley into the Mid-Atlantic, isolated severe hail or wind is possible during the day.

Severe Outlook

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 47,289 2,762,058 Norman, OK…Wichita Falls, TX…Lawton, OK…Broken Arrow, OK…Muskogee, OK…
SLIGHT 218,024 19,885,612 Dallas, TX…Fort Worth, TX…Oklahoma City, OK…Kansas City, MO…Tulsa, OK…
MARGINAL 378,142 52,006,921 Chicago, IL…Indianapolis, IN…Columbus, OH…Charlotte, NC…Milwaukee, WI…

Analysis

Low pressure will move across Iowa during the day today and bring a warm front across Missouri into Central Illinois and across the remainder of the Ohio Valley. A very moist air mass exists behind this front supporting scattered storms during the day from Iowa into the Ohio Valley.  Warm advection will allow for development of storms across Virginia and North Carolina under the influence of the disturbance currently causing thunderstorms in Kentucky.

Moderate to strong mid-level flow will spread into the Oklahoma and Far Northern Texas area as a weak cold front extends from Missouri down into Northwestern Texas by late this afternoon. A very warm and moist air mass is already in place though current storms in the area will play a pivotal role in destabilization during the day.  Strong instability will lead to intense clusters of thunderstorms with the primary threats of wind and large hail across the enhanced risk area.  A couple of tornadoes cannot be ruled out for this region.

Substantial moisture and instability is currently developing over Eastern Kansas and Western Missouri causing cluster of thunderstorms to form during the overnight hours. This activity is expected to continue during the morning hours with a threat of large hail.  Further development of stronger storms during the early afternoon will present a risk of damaging winds as a mesoscale convective system develops.

Dewpoints in the 60s across Iowa are forecast to result in a small corridor of supercell activity. Some heating is expected during the day as shear profiles are locally enhanced by the presence of the low pressure system.  Hail will be the primary threat with these storms but there is a risk of tornadoes later in the afternoon.

This Week’s Flood Risk

Flood Risk

Yesterday’s Storm Reports

storm reports 2

Robert Millette

Staff Meteorologist

Firsthand Weather