449
ACUS48 KWNS 190836
SWOD48
SPC AC 190834
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0334 AM CDT TUE MAR 19 2019
VALID 221200Z - 271200Z
..DISCUSSION
THE LONGWAVE PATTERN WILL REMAIN GENERALLY UNFAVORABLE FOR ANY
APPRECIABLE SEVERE THREAT THROUGH AT LEAST D4/FRI. AT THIS TIME, A
SURFACE RIDGE AXIS WILL SHIFT EASTWARD TOWARD THE MISSISSIPPI RIVER
VALLEY, ALLOWING FOR A MODIFIED MARITIME AIRMASS TO MIGRATE
NORTHWESTWARD FROM THE WESTERN GULF INTO TEXAS. MEANWHILE,
STRENGTHENING MID-LEVEL FLOW WILL MIGRATE NORTHEASTWARD ACROSS THE
HIGH PLAINS ATOP A SHARPENING LEE SURFACE TROUGH/DRYLINE, PROVIDING
IMPETUS FOR CONVECTIVE DEVELOPMENT ACROSS THE TEXAS PANHANDLE/SOUTH
PLAINS. MEAGER INSTABILITY SHOULD LIMIT THE EXTENT OF ANY SEVERE
THREAT DURING THIS TIMEFRAME. THIS DRYLINE SHOULD SHIFT SLIGHTLY
EASTWARD INTO WESTERN OKLAHOMA/WEST-CENTRAL TEXAS ON D5/SAT AS
MID-LEVEL FORCING FOR ASCENT LIFTS NORTHWARD AWAY FROM THE DEEPER
BOUNDARY LAYER MOISTURE.
GUIDANCE SUGGEST THAT A MORE APPRECIABLE SEVERE THREAT SHOULD
DEVELOP AROUND D6/SUN ACROSS PORTIONS OF THE SOUTHERN PLAINS. BY
THIS TIME, LOW 60S F DEWPOINTS WILL HAVE DEVELOPED NORTHWARD TO AT
LEAST THE RED RIVER VALLEY AREA - AND POSSIBLY NORTHWARD THROUGH
SOUTHERN OKLAHOMA. MEANWHILE, A JET STREAK ON THE SOUTHERN EXTENT
OF A PROGRESSIVE SHORTWAVE WILL MIGRATE EASTWARD ATOP THE REMAINING
DRYLINE AND NEARBY WARM SECTOR. WEAK TO MODERATE SURFACE-BASED
INSTABILITY AND SUPERCELLULAR VERTICAL WIND PROFILES WILL LIKELY
FAVOR ALL MODES OF SEVERE WEATHER, WITH THE REMAINING UNCERTAINTY
INVOLVING SPECIFIC POSITIONING OF RELATED SURFACE FEATURES (I.E.,
DRYLINE POSITION, NORTHWARD EXTENT OF SURFACE-BASED INSTABILITY) AND
SPECIFIC ORIENTATION OF THE MID-LEVEL JET AND ATTENDANT MID-LEVEL
WAVE.
BY D7/MON, THIS THREAT SHOULD SHIFT EASTWARD/SOUTHEASTWARD IN TANDEM
WITH AN EASTWARD-MOVING SURFACE LOW AND A SOUTHWARD MOVING COLD
FRONT ENTERING THE TENNESSEE VALLEY. IT APPEARS THAT AT LEAST A
MARGINAL THREAT FOR SEVERE WEATHER WILL EXIST WITHIN THE WARM SECTOR
ALONG AND AHEAD OF THESE SURFACE FEATURES, THOUGH A FAIR AMOUNT OF
UNCERTAINTY EXISTS WITH SPECIFIC POSITIONING OF THESE SURFACE
FEATURES AND UPSTREAM MID-LEVEL WAVE EVOLUTION.
..COOK.. 03/19/2019
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