The Storm Prediction Center has upgraded portions of East Texas to a level 5 High Risk of Severe Thunderstorms. This is an extremely rare risk and signifies the potential for violent tornadoes. Center, Nacogdoches, Lufkin, Jasper, and Burkeville are a few towns included. This is a dangerous situation evolving this afternoon in far East Texas – and folks there need to pay extremely close attention to the forecast. If a tornado warning is issued for your area, get into shelter immediately. A level 4 risk of severe weather remains in place for portions of East and Southeast Texas, with a level 3 risk in eastern North Texas, eastern Central Texas, the Brazos Valley, into Southeast Texas.

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT SUN APR 02 2017

VALID 021630Z – 031200Z

…THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
FAR EAST TEXAS AND NORTHERN LOUISIANA…

…THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
HIGH ACROSS PORTIONS OF EAST TEXAS…NORTHERN AND CENTRAL
LOUISIANA…CENTRAL AND SOUTHERN MISSISSIPPI…AND EXTREME SOUTHERN
ARKANSAS…

…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
MODERATE FROM PORTIONS OF EAST TEXAS TO MISSISSIPPI…

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED FROM PORTIONS OF EAST AND SOUTH TEXAS TO FAR WESTERN
ALABAMA…

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT FROM EASTERN PORTIONS OF THE SOUTHERN PLAINS TO WESTERN
ALABAMA…

..SUMMARY

WIDESPREAD SEVERE THUNDERSTORMS CAPABLE OF SIGNIFICANT TORNADOES,
SEVERE WIND, AND SEVERE HAIL WILL SPREAD ACROSS PORTIONS OF EAST
TEXAS TO THE LOWER MISSISSIPPI VALLEY THROUGH TONIGHT. THE GREATEST
RISK FOR TORNADOES WILL EXIST FROM PORTIONS OF FAR EAST TEXAS
EASTWARD ACROSS NORTHERN LOUISIANA THIS AFTERNOON AND EVENING.

…PORTIONS OF EAST TEXAS TO THE LOWER MISSISSIPPI VALLEY THROUGH
TONIGHT…
A LONG-LIVED THUNDERSTORM CLUSTER THAT CROSSED CENTRAL TEXAS THROUGH
THE OVERNIGHT/MORNING HOURS IS LOSING ORGANIZATION AS IT IS
ADVANCING INTO EAST TEXAS. CONVECTION CONTINUES TO FORM AHEAD OF THE
REMNANT OUTFLOW BOUNDARY RELATED TO THE CLUSTER — FROM PARTS OF THE
UPPER TX COAST THROUGH THE LOWER SABINE VALLEY REGION WITHIN A
WARM-ADVECTION PLUME. THIS PLUME OF WARM ADVECTION IS ASSOCIATED
WITH AN AMPLIFYING MIDLEVEL SHORTWAVE TROUGH, WHOSE ACCOMPANYING
MIDLEVEL SPEED MAXIMUM IS EMERGING OVER SOUTH TEXAS. AS THE
SHORTWAVE TROUGH CONTINUES TO ADVANCE EASTWARD, THE LOW-LEVEL MASS
RESPONSE WILL FACILITATE POLEWARD RETURN OF RICH BOUNDARY-LAYER
MOISTURE — E.G., 15 G/KG MEAN MIXING RATIO PER LAKE CHARLES 12Z
OBSERVED SOUNDING. AS SUCH, AN EXPANSIVE WARM SECTOR ASSOCIATED WITH
MLCAPE AROUND 1500-3000 J/KG WILL BECOME ESTABLISHED THROUGH THE
AFTERNOON FROM THE WESTERN/CENTRAL GULF COAST NORTHWARD TO A
PRECIPITATION-REINFORCED WARM FRONTAL ZONE FORECAST TO EXTEND FROM
PART OF EAST-CENTRAL TX EASTWARD ACROSS NORTHERN LOUISIANA.

WITH OPEN-WARM-SECTOR CONVECTIVE DEVELOPMENT NOW BECOMING APPARENT
AHEAD OF THE REMNANTS OF THE CONVECTIVE CLUSTER, IT IS EXPECTED THAT
THIS ACTIVITY WILL MATURE AS IT INTERACTS WITH THE
NORTHWARD-ADVANCING WARM FRONTAL ZONE. THIS IS WHERE EFFECTIVE SRH
AROUND 300-400 M2/S2 AMID STRONG DEEP SHEAR AND INCREASING BUOYANCY
WILL EXIST. GIVEN INCREASING CONFIDENCE IN SEMI-DISCRETE
SUPERCELLS/SUPERCELL CLUSTERS INTERACTING WITH THIS WARM FRONTAL
ZONE AROUND PEAK HEATING, CONFIDENCE HAS INCREASED IN GREATER
TORNADO POTENTIAL — INCLUDING SIGNIFICANT TORNADOES — ACROSS THE
NOW-UPGRADED HIGH RISK AREA. THE SIGNIFICANT-TORNADO POTENTIAL WILL
SPREAD TOWARD THE LOWER MISSISSIPPI VALLEY INTO THE EVENING HOURS.