Strong Tornadoes Likely Across South

Strong tornadoes are likely today into tonight for parts of the South extending northward into Tennessee and southern parts of Kentucky. This will be the first severe thunderstorm and tornado outbreak of the year, which is why the Storm Prediction Center has issued its first moderate risk of the year (see Fig. 1). The moderate risk extends from south-central Tennessee into northern & central Mississippi and northwestern Alabama. Surrounding the moderate risk is an enhanced risk which extends from southern Kentucky southward into northeastern Louisiana.

Fig. 1: Thunderstorm outlook for Saturday (from the SPC)

A strong, negatively tilted shortwave trough is advancing eastward this morning from the Southern Plains. With this trough is a strong jet aloft. Ahead of the trough and jet, across the South, 60 & 70 degree dewpoints have already surged northward due to a strong surface low that is deepening in the Plains (this low is responsible for the blizzard conditions from the Texas Panhandle into Iowa). This will set the stage for very intense, rotating updrafts this afternoon. At this hour (this morning), intense thunderstorms have already developed across western Arkansas extending southward into northwestern Louisiana and eastern Texas. These storms will race eastward into the Mississippi Delta by this afternoon. At that point, all the atmospheric conditions will be primed for strong tornadoes. Along with strong tornadoes (see Fig. 2), large hail (see Fig. 3) and damaging winds (see Fig. 4) are possible. Other hazards are lightning and flash flooding.

Fig. 2: Tornado probabilities for Saturday (from SPC)
Fig. 3: Hail probabilities for Saturday (from SPC)
Fig. 4: Damaging wind probabilities for Saturday (from SPC)

Here is a snapshot of what the radar may look like early this afternoon (see Fig. 5) and by early evening (see Fig. 6). Notice the primary broken line of thunderstorms along with the isolated storms ahead of this line. It is possible tornadoes may exist in the line of thunderstorms with discreet supercells (producing tornadoes) out ahead of the main line.

Fig. 5: Simulated radar early Saturday afternoon
Fig. 6: Simulated radar early Saturday evening

Make sure you are weather-alert today & tonight. Have a plan in place in case a warning is issued for your area!

Southern Plains Winter Storm & Mid-Atlantic Storm

A winter storm will impact part of the Southern Plains on Tuesday. A deep trough is moving east this afternoon across the western United States. As the trough continues to advance eastward, moisture will rapidly lift northward into the Plains. An approaching jet streak will allow precipitation to develop across Texas early Tuesday morning, lifting northward into parts of Oklahoma, Kansas, Arkansas and Missouri. Surface temperatures are cold, plus with evaporational cooling, it will set the stage for a wintry mixture for the aforementioned areas throughout the day on Tuesday.

Modeled soundings suggest north Texas (near the Red River), southern and central Oklahoma, central Arkansas and southern Missouri will see a period of freezing rain. North Texas and central Oklahoma will likely transition from freezing rain to rain by the afternoon hours on Tuesday (which will limit ice accumulations). Farther north, the freezing rain should transition to snow as evaporational cooling takes care of the small warm-nose aloft.

Snow (see Fig. 1) and ice (see Fig. 2) accumulations are likely for much of the Southern Plains. This is why local National Weather Service offices have issued Winter Weather Advisories for this region (see Fig. 3). It is likely that travel will be impacted by this winter storm.

Fig. 1: Modeled snow accumulations (please note: this should be used as an idea of where snow will fall. Amounts may vary)
Fig. 2: Modeled ice accumulations (please note: this should be used as an idea of where freezing rain will fall. Amounts may vary)
Fig. 3: Current winter weather alerts

Wintry precipitation is also possible Tuesday evening into Wednesday for parts of the Carolinas and Mid-Atlantic. A potent low will move towards this region by mid-week allowing an area of widespread wintry precipitation to develop. It appears the higher terrain of North Carolina northward into the Virginias could see an extended period of freezing rain. Ice accumulations around 1/4th of an inch are likely with some higher totals. The freezing rain in North Carolina may transition to rain, while locations farther north may see a transition to a sleet/snow mixture by Wednesday. Significant snow (see Fig. 4) and ice (see Fig. 5) are possible for this region, which is why the local National Weather Service offices have issued Winter Storm Warnings and Winter Weather Advisories for this region (see Fig. 6).

Fig. 4: Modeled snow accumulations (please note: this should be used as an idea of where snow will fall. Amounts may vary)
Fig. 5: Modeled ice accumulations (please note: this should be used as an idea of where freezing rain will fall. Some of the amounts may be too high. Amounts may vary. Freezing rain will likely not extend into GA/SC as this model shows.)
Fig. 6: Current winter weather alerts

Southeast Flooding

The flood risk is high across the Southeast to wrap up February. The storm track, which has been just north of the Southeast, will shift south allowing for several wet storms to move from the Mississippi Valley towards the east and north. As the storm track moves south this upcoming week, several disturbances will move across the Southeast. Each one creating enough lift to generate rain. Periodically, stalled frontal boundaries will be located across this region, which will act to enhance rainfall–increasing the flood threat.

It is difficult to pinpoint exactly which area will see the heaviest rainfall but at this time it appears widespread 3-6″ will fall from Louisiana east through Mississippi, Alabama, Georgia and north into parts of Tennessee and Kentucky this week with isolated 5-10″ amounts (see Fig. 1). The heavy rain axis will also extend farther east in north into Virginia and the Carolinas.

Fig. 1: Rainfall forecast through next week

The soil is saturated in this region from above average precipitation during the cool season. This, paired with a lack of foliage due to the cold season, will allow for quick runoff into area streams, creeks and rivers this upcoming week. Please remain alert of your surroundings. And, as always, TURN AROUND, DON’T DROWN!

Sleet And Snow For Texas

Light wintry precipitation is possible across parts of north Texas and central Texas Friday midday into Friday night. Weak southwesterly flow (carrying moisture from the Pacific), coupled with a shortwave overhead will lead to the development of precipitation. Precipitation will develop across the Texas Hill Country and central Texas Friday morning (see Fig. 1) before lifting northward into north Texas by Friday afternoon (see Fig. 2). 

Fig. 1: Future radar Friday morning (please note: this is just to give a general idea of where precipitation will be Friday morning)
Fig. 2: Future radar Friday afternoon (please note: this is just to give a general idea of where precipitation will be Friday afternoon)

Initially, the precipitation will not reach the ground due to the cold front that pushed through the state this morning leaving behind very dry air near the surface. However, throughout the day on Friday, the atmosphere will moisten, leading to precipitation reaching the ground. While surface temperatures appear to be marginal for wintry precipitation, it is likely that the evaporation of the onset of precipitation will lead to cooling of the surface temperatures to near 32 degrees (see Fig. 3).

Fig. 3: Friday afternoon temperatures

Modeled soundings suggest central Texas and southern parts of north Texas (south of I-20) will see a rain & sleet mixture (see Fig. 4). North of I-20, modeled soundings show a profile supportive of light snow (see Fig. 5). With surface temperatures hovering near the 32 degree mark, it is likely accumulations will be minimal to non-existent. Another hindering factor for accumulations is the light nature of the precipitation. If a moderate burst of precipitation occurs, it is possible a quick slushy accumulation may occur in some areas. The best chance accumulations of sleet appears to be along and south of I-20 where the greatest moisture will reside (see Fig. 6).

Fig. 4: Modeled sounding central Texas Friday morning
Fig. 5: Modeled sounding north Texas Friday afternoon
Fig. 6: Wintry precipitation map

It is possible a rain/sleet mixture may move into northern Louisiana and southern Arkansas late Friday night. It is possible moisture may try to edge towards the southern counties of Oklahoma so this will need to be monitored. No accumulations are expected.