DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0700 AM CST THU FEB 16 2023
VALID 161300Z - 171200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
MISSISSIPPI TO CENTRAL KENTUCKY...
..SUMMARY
WIDELY SCATTERED SEVERE THUNDERSTORMS ARE LIKELY FROM THE CENTRAL
GULF COAST STATES NORTHWARD INTO THE OHIO VALLEY. STRONG TORNADOES
ARE MOST LIKELY OVER MISSISSIPPI, ALABAMA AND MIDDLE TENNESSEE.
..SYNOPSIS
IN MID/UPPER LEVELS, THE MOST IMPORTANT FEATURE FOR THIS CONVECTIVE
CYCLE WILL BE A POSITIVELY TILTED SYNOPTIC TROUGH, INITIALLY
APPARENT IN MOISTURE-CHANNEL IMAGERY FROM NEAR OMA SOUTHWESTWARD
THROUGH A SMALL CLOSED CYCLONE OVER NORTHWESTERN KS/SOUTH-CENTRAL
NE, TO THE NORTHERN TX PANHANDLE, SOUTH-CENTRAL NM AND SOUTHERN AZ.
AN INITIALLY SEPARATE, NORTHERN-STREAM PERTURBATION OVER MB AND THE
DAKOTAS WILL MOVE SOUTHEASTWARD AND AMPLIFY THROUGH THE DAY,
GRADUALLY PHASING WITH THE SOUTHERN TROUGH. BY 00Z, THE RESULT
SHOULD BE A LENGTHY TROUGH FROM LAKE SUPERIOR SOUTHWESTWARD TO THE
SOUTHERN HIGH PLAINS AND OVER THE ELP/DMN CORRIDOR. BY 12Z, THE
TROUGH SHOULD EXTEND FROM LOWER MI ACROSS THE OZARKS TO CENTRAL TX.
AT THE SURFACE, 11Z ANALYSIS SHOWED A SURFACE LOW OVER THE EAST-
CENTRAL OZARKS NEAR THE AR/MO BORDER, WITH COLD FRONT SOUTHWESTWARD
ACROSS THE ARKLATEX TO THE MIDDLE TX COASTAL PLAIN AND DEEP SOUTH
TX. THROUGH THE DAY, AS THE SURFACE LOW MOVES TOWARD SOUTHERN IN,
THE COLD FRONT SHOULD SWEEP SOUTHEASTWARD ACROSS THE LOWER/MID
MISSISSIPPI VALLEY, AND THE REMAINDER OF SOUTH/SOUTHEAST TX INTO THE
GULF AND NORTHEASTERN MX. BY 00Z, THE LOW SHOULD BE NEAR THE IN/OH
BORDER, WITH COLD FRONT ACROSS CENTRAL KY, MIDDLE TN, SOUTHERN MS,
AND SOUTHEASTERN LA. BY 12Z, THE LOW SHOULD BE OVER EASTERN/CENTRAL
NY NEAR UCA, WITH COLD FRONT FROM THERE ACROSS CENTRAL PA, WESTERN
PARTS OF VA/NC, CENTRAL/SOUTHWESTERN GA, THE CENTRAL/WESTERN FL
PANHANDLE, AND THE CENTRAL/SOUTHWESTERN GULF.
..CENTRAL GULF STATES TO OHIO VALLEY
ONGOING STRONG/ISOLATED SEVERE THUNDERSTORMS ARE NOTED IN TWO MAIN
CORRIDORS -- ONE OVER WESTERN PARTS OF TN/KY, ANOTHER NEAR THE COLD
FRONT OVER AR. SEE SPC TORNADO WATCH 37 AND RELATED MESOSCALE
DISCUSSIONS FOR NEAR-TERM CONCERNS.
AN ADDITIONAL ROUND OF CONVECTION IS EXPECTED TO DEVELOP AHEAD OF
THE SURFACE COLD FRONT AS DIURNAL HEATING DESTABILIZES A FAVORABLY
MOIST WARM SECTOR, AMIDST WEAKENING MLCINH. THE MOST PROBABLE AREA
AND TIMING FOR THIS DEVELOPMENT APPEARS TO BE LATE MORNING INTO
EARLY AFTERNOON ACROSS SOUTHEASTERN LA AND SOUTHERN MS, MOVING/
BUILDING NORTHEASTWARD INTO MORE OF MS/AL INTO THE AFTERNOON.
SURFACE DEWPOINTS IN THE MID 60S TO NEAR 70 F, AT THE BOTTOM OF A
DEEP BOUNDARY LAYER WITH UP TO ABOUT 1.5-INCH PW, WILL CONTRIBUTE TO
MLCAPE COMMONLY AROUND 1500 J/KG, LOCALLY NEAR 2000 J/KG.
KINEMATICALLY, A PERIOD OF STRENGTHENING SHEAR IS EXPECTED INTO THE
AFTERNOON, FOLLOWED BY LEVELING OFF AND PERHAPS SOME LESSENING OF
SHEAR DUE TO VEERING SURFACE WINDS. THIS WILL LEAD TO VARYING BUT
GENERALLY LARGE HODOGRAPH SIZES AND SHAPES, BUT WITH EFFECTIVE SRH
GENERALLY REMAINING IN THE 250-400 J/KG RANGE OVER MUCH OF THE AREA.
THE WIND PROFILES THROUGHOUT THAT CYCLE WILL BE FAVORABLE FOR
SUPERCELLS, WITH EFFECTIVE-SHEAR MAGNITUDES IN THE 45-55-KT RANGE
OVER SOUTHERN AREAS, TO 50-60 KT ACROSS THE TENNESSEE VALLEY REGION.
A NORTHWARD EXTENSION OF SIGNIFICANT-TORNADO PROBABILITIES IS BEING
MADE ACCORDINGLY, AND SOME PARTS OF THIS REGION MAY NEED A FURTHER,
TACTICALLY FOCUSED, TORNADO-DRIVEN UPGRADE TODAY, AS MESOSCALE
TRENDS AND LATER OBJECTIVE GUIDANCE WARRANT.
THE STRONGEST UNCONDITIONAL PARAMETER SPACE FOR SIGNIFICANT-TORNADO
POTENTIAL THIS AFTERNOON AND EVENING STILL APPEARS TO BE IN THE
CORRIDOR FROM SOUTHERN MS TO MIDDLE TN AND WESTERN/CENTRAL/NORTHERN
AL, BUT THAT DOESN'T PRECLUDE ONE FARTHER NORTH INTO A MUCH MORE
CONDITIONAL REGIME AS WELL. DEEP SHEAR AND SRH WILL REMAIN
FAVORABLE NORTHWARD INTO THE OHIO VALLEY, BUT INSTABILITY AT ALL
DEPTHS SHOULD DIMINISH DUE TO A COMBINATION OF ANTECEDENT PRECIP AND
LESS-MATURE, LOWER-THETA-E RETURN FLOW. AS FRONTAL/PREFRONTAL
CONVECTION MOVES OVER THE REGION, A BLEND OF LINEAR AND PRECURSORY
SUPERCELL MODES IS POSSIBLE, WITH DAMAGING TO SEVERE WIND BEING THE
MOST COMMON EVENT, AND A FEW TORNADOES ALSO POSSIBLE. SEVERE
POTENTIAL ALSO SHOULD DIMINISH IN THE OHIO VALLEY CORRIDOR SOONER
THAN THE GULF COAST STATES, AS THE FRONTAL/PREFRONTAL CONVECTION
OUTRUNS A NARROWER WARM SECTOR.
