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| Probabilistic Tornado Graphic | |||||||||
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| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
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| Probabilistic Damaging Wind Graphic | |||||||||
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| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
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| Probabilistic Large Hail Graphic | |||||||||
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
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SPC AC 221627 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1127 AM CDT FRI MAR 22 2013 VALID 221630Z - 231200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NORTHEAST TX...NORTHERN LA...AND WESTERN MS... ...ARKLATEX... WATER VAPOR LOOPS CONTINUE TO SHOW A PRONOUNCED UPPER TROUGH DEVELOPING ACROSS THE GREAT BASIN...WHILE SHORTWAVE RIDGING OCCURS OVER PORTIONS OF NM/TX. AT THE SURFACE...A WEAK LOW IS ANALYZED NEAR DAL WITH A WARM FRONT EXTENDING EAST-SOUTHEASTWARD ACROSS EAST TX INTO SOUTHERN LA. THE WARM FRONT IS FORECAST TO PROGRESS SLOWLY NORTHWARD THROUGH THE DAY WITH A MOIST AND MODERATELY UNSTABLE AIR MASS SPREADING INTO CENTRAL/NORTHERN LA AND PARTS OF WESTERN MS BY EVENING. THESE FACTORS WILL RESULT IN A REGION OF CONDITIONAL RISK FOR SEVERE THUNDERSTORMS THIS EVENING AND EARLY TONIGHT. ONE OF THE MAIN FORECAST UNCERTAINTIES INVOLVES WEAK LARGE SCALE ASCENT THAT WILL BE PRESENT OVER THE RISK AREA TODAY. WEAK LOW LEVEL WARM ADVECTION IS OCCURRING...AND THIS LIFT MAY HELP TO SLOWLY WEAKEN THE CAPPING INVERSION SHOWN ON MORNING SOUNDINGS. HOWEVER...MODEL SOLUTIONS SHOW CONSIDERABLE DISPERSION REGARDING LOCATION AND TIMING OF DEEP CONVECTION. FORECAST SOUNDINGS FROM NORTHEAST TX INTO WESTERN MS SHOW STEEP MID LEVEL LAPSE RATES...MODERATE CAPE VALUES...AND SUFFICIENT LOW LEVEL/DEEP LAYER VERTICAL SHEAR FOR A RISK OF SUPERCELL STRUCTURES IN ANY STORMS THAT CAN FORM. HAIL/DAMAGING WINDS WOULD BE THE MAIN THREAT...ALTHOUGH ISOLATED TORNADOES WOULD ALSO BE A CONCERN. ...SOUTH FL... STRENGTHENING SEA BREEZE CIRCULATIONS WILL AUGMENT LOW-LEVEL ASCENT INVOF A DIFFUSE SFC FRONT THAT WILL GRADUALLY ADVANCE NWD THROUGH THE DAY. INSOLATION/DIABATIC HEATING -- LIMITED TO SOME EXTENT BY MULTI-LAYERED CLOUDINESS STREAMING EWD FROM THE GULF -- WILL SUPPORT MODEST BOUNDARY-LAYER DESTABILIZATION AS LOWER/MIDDLE 60S DEWPOINTS SPREAD NWD. ISOLATED TO SCATTERED PRIMARILY LOW-TOPPED CONVECTION MAY DEVELOP IN RESPONSE TO THE DIURNALLY STRENGTHENING LOW-LEVEL ASCENT...AND WEAK MID-LEVEL ASCENT PRECEDING A WEAK SHORTWAVE IMPULSE OVER THE MIDDLE GULF. MODEST DIRECTIONAL SHEAR IN THE LOW LEVELS COULD SUPPORT A WEAKLY ROTATING UPDRAFT OR TWO. HOWEVER...ASIDE FROM WEAK LOW-LEVEL WAA/ISENTROPIC ASCENT...DEEP FORCING FOR ASCENT WILL BE LACKING...WHILE MID-LEVEL HEIGHT RISES/WARMING OFFSET THE POTENTIAL FOR DEEP CONVECTION. AS SUCH...CONVECTION SHOULD STRUGGLE TO DEEPEN SUFFICIENTLY INTO ICING LAYERS ALOFT TO SUPPORT ANY MORE THAN AN ISOLATED THUNDERSTORM OR TWO. FURTHERMORE...THE LACK OF DEEPER CONVECTION WILL LIKELY PREVENT STORMS FROM INTERACTING WITH THE STRONGER MID-LEVEL FLOW...PRECLUDING A THREAT FOR DEEPER/ORGANIZED CONVECTIVE STRUCTURES. ..HART/COHEN/MARSH.. 03/22/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z |