Day 3 Severe Weather Outlook

USA Weather — Severe Weather Division

This outlook is expired and is no longer valid.

Issued
11:44Z Mon, May 23
Valid
12Z Wed, May 25 - 12Z Thu, May 26
Forecaster
Wyatt Huber

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE WESTERN GULF COAST INTO THE LOWER MISSISSIPPI VALLEY...

...SUMMARY...

SEVERE THUNDERSTORMS CAPABLE OF DAMAGING WINDS, LARGE HAIL, AND A FEW TORNADOES ARE POSSIBLE WEDNESDAY ACROSS THE WESTERN GULF COAST INTO THE LOWER MISSISSIPPI VALLEY. 

...SYNOPSIS...

A SPRING-LIKE TROUGH EJECTION IS POISED TO OCCUR ON TUESDAY. BY THE START OF THE PERIOD WEDNESDAY, A STRONG NUTERALLY TILTED LONGWAVE TROUGH WILL BE LOCATED THROUGH THE PLAINS. IT WILL QUICKLY SHIFT EASTWARD TO THE MID-MISSISSIPPI VALLEY BY THE END OF THE PERIOD, WHILE REMAINING NEUTRALLY TO PERHAPS VERY SLIGHTLY NEGATIVALLY TILTED. AT THE SURFACE, A DEEPENING CYCLONE SHOULD BE LOCATED OVER MISSOURI BY THE START OF THE PERIOD AND QUICKLY SHIFTING NORTHEASTWARD TO THE GREAT LAKES BY THE END OF THE PERIOD. A STRONG COLD FRONT FOR THIS TIME OF THE YEAR WILL SHIFT EASTWARD THROUGH THE PERIOD. THIS SPRING-LIKE PATTERN SHOULD BRING A SEVERE POTENTIAL TO THE GULF COAST AND LOWER MISSISSIPPI VALLEY. A LESSER SEVERE THREAT EXTENDS NORTHEASTWARD THROUGH THE MIDWEST.

...WESTERN GULF COAST/LOWER MISSISSIPPI VALLEY INTO THE MIDWEST...

AT THE START OF THE PERIOD, STRONG SOUTHERLY LOW-LEVEL FLOW SHOULD BRING CONTINUED SURGES OF DEEP MOISTURE NORTHWARD INTO THE WARM SECTOR. SURFACE DEWPOINTS AHEAD OF THE COLD FRONT/PRE-EXISTING SQUALL LINE SHOULD BE IN THE LOW TO MID 70S. HIGHLY UNSTABLE AIR SHOULD RESULT FROM THIS DEEP MOISTURE, WITH MLCAPE VALUES LIKELY 2000-4000 J/kg. A STRENGTHENING LLJ IS ALSO NOTED. 850MB WIND VALUES SHOULD INCREASE TO BETWEEN 40 AND 50 KNOTS. SOUNDINGS OVER SOUTHERN MISSISSIPPI AND LOUISIANA REVEAL THAT THERE WILL BE DECENT CURVATURE OF HODOGRAPHS IN THE LOWEST 3 KM OF THE SURFACE. THIS COULD RESULT IN SRH VALUES IN THE RANGE OF 100-300 m2/s-2.

AN ONGOING SQUALL LINE WILL LIKELY BE ONGOING AT THE START OF THE PERIOD OVER EASTERN TEXAS. WITH LOSS OF DAYTIME HEATING, IT IS PLAUSABLE THAT THIS SQUALL WILL BE SUB-SEVERE AND WEAKENING. THROUGH THE MID-MORNING HOURS, THERE COULD STILL BE AN ISOLATED DAMAGING WIND GUST ALONG THE TEXAS COAST FROM THIS SQUALL. BY THE AFTERNOON, ENOUGH DESTABALIZATION OF THE AIRMASS AND STRONG MOISTURE CONVERGENCE FROM NOW SOUTHEASTERLY LOW-LEVEL FLOW SHOULD RESULT IN ADDITIONAL THUNDERSTORM DEVELOPMENT ACROSS THE WESTERN GULF COAST AND ALONG THE COLD FRONT. THESE STORMS WILL LIKELY BE A MIX OF MULTICELL CLUSTERS AND A FEW SUPERCELLS AHEAD OF THE REGENERATING SQUALL LINE ALONG THE COLD FRONT. LOW-LEVEL WIND PROFILES WILL BE SUPPORTIVE FOR SOME OF THESE SUPERCELLS TO BE CAPABLE OF PRODUCING TORNADOES. IN ADDITION, LARGE HAIL AND DAMAGING DOWNBURSTS ARE A CONCERN GIVEN 6.5-7.5 C/KM LAPSE RATES AND STRONG DCAPE. ALONG THE SQUALL LINE, A FEW EMBBEDED CIRCULATIONS CAPABLE OF TORNADOES IN ADDITION TO DAMAGING WINDS ARE POSSIBLE. 

THE SEVERE THREAT SHOULD BECOME LESS DEFINED WITH NORTHWARD EXTEND DUE TO LIMITED INSTABILITY. A MARGINAL SEVERE THREAT STILL EXTENDS WELL NORTHWARD INTO THE MIDWEST REGION, WHERE A FEW DAMAGING WIND GUSTS AND LARGE HAILSTONES ARE POSSIBLE.