Apr 22, 2015 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1258 AM CDT WED APR 22 2015

   VALID 221200Z - 231200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS ALONG THE RED RIVER AND PARTS
   OF N TX...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN HIGH PLAINS TO THE
   WRN GULF COAST/LOWER MS VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE S-CNTRL
   STATES...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE MID-ATLANTIC STATES TO
   THE SRN APPALACHIANS...

   ...SUMMARY...
   ISOLATED TO SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED FROM THE
   SOUTHERN HIGH PLAINS TO ALONG THE RED RIVER...AND SOUTH TOWARDS THE
   WESTERN GULF COAST BEGINNING THIS AFTERNOON. LOCALLY DAMAGING WINDS
   AND ISOLATED MARGINALLY SEVERE HAIL ARE POSSIBLE FROM THE
   MID-ATLANTIC STATES TO THE SOUTHERN APPALACHIANS THIS AFTERNOON.

   ...SYNOPSIS...
   A SPLIT FLOW...BLOCKING SYNOPTIC REGIME WILL PREVAIL WITH
   A LARGE UPPER TROUGH OVER THE EAST...A CUTOFF LOW OVER SRN CA
   AND AN UPPER RIDGE INITIALLY OVER THE NRN ROCKIES. THIS RIDGE WILL
   GRADUALLY SHIFT E TO THE NRN HIGH PLAINS AS A NRN-STREAM SHORTWAVE
   TROUGH SHIFTS INLAND OVER THE PACIFIC NW. AT THE SURFACE...A COLD
   FRONT WILL SWEEP E OF THE APPALACHIANS THIS AFTERNOON WITH TRAILING
   PORTION OF THIS BOUNDARY SINKING S BEFORE BECOMING QUASI-STATIONARY
   NEAR THE RED RIVER. THIS FRONT SHOULD INTERSECT THE DRYLINE OVER THE
   SRN TX PANHANDLE IN THE AFTERNOON WITH SRN PORTION OF THE DRYLINE
   BULGING E OVER THE CONCHO VALLEY.

   ...S-CNTRL CONUS...
   22/00Z RAOBS AND GOES PW IMAGERY CONFIRM THAT THE MARITIME TROPICAL
   AIR MASS IS CURRENTLY CONFINED ACROSS DEEP S TX INTO THE WRN
   GULF...CHARACTERIZED BY MEAN MIXING RATIOS AROUND 14 G/KG PER BRO
   RAOB. THE PRE-FRONTAL WARM SECTOR WILL CONTINUE TO MODIFY WITHIN
   MODEST LOW-LEVEL SLYS AND SHOULD RESULT IN MEAN MIXING RATIOS NEAR
   12 G/KG REACHING THE RED RIVER BY LATE AFTERNOON TO AROUND 16 G/KG
   ALONG THE TX GULF COAST. THIS INCREASING BOUNDARY-LAYER MOISTURE
   WILL OCCUR BENEATH AN EML PLUME WITH THE STEEPEST MID-LEVEL LAPSE
   RATES PROGGED FROM THE SRN HIGH PLAINS ACROSS THE RED RIVER. BY LATE
   AFTERNOON...MLCAPE SHOULD PREDOMINATELY REACH 1500-2500 J/KG.

   MID-LEVEL HEIGHT CHANGE DURING THE 24-H PERIOD SHOULD BE NEUTRAL TO
   WEAKLY RISING WITH LOW-AMPLITUDE SHORTWAVE RIDGING. HOWEVER...WATER
   VAPOR IMAGERY AND GUIDANCE SUGGEST A FEW SUBTLE SRN-STREAM IMPULSES
   SHOULD HELP TO FOCUS CONVECTION TODAY. A CLUSTER OF ELEVATED TSTMS
   SHOULD BE ONGOING THIS MORNING WITHIN A ZONE OF ISENTROPIC ASCENT
   ALONG/N OF THE COLD FRONT ACROSS OK. THIS SHOULD EFFECTIVELY
   DISPLACE THE FRONT S AND YIELD ROBUST DIFFERENTIAL HEATING ALONG IT.
   AN IMPULSE EVIDENT OVER AZ MAY REACH THE SRN HIGH PLAINS THIS
   AFTERNOON. UPSLOPE ALONG THE HIGHER TERRAIN AND CONVERGENCE NEAR THE
   FRONT-DRYLINE INTERSECTION WILL LIKELY RESULT IN SCATTERED TSTMS
   DEVELOPING LATE DAY. ELONGATED/STRAIGHT-LINE HODOGRAPHS WILL FAVOR
   SPLITTING SUPERCELLS CAPABLE OF VERY LARGE HAIL AND ISOLATED SEVERE
   WINDS. A COUPLE TORNADIC SUPERCELLS COULD EVOLVE CLOSE TO THE
   TRIPLE-POINT WHERE LOW-LEVEL SRH IS ENHANCED NEAR THE FRONT.
   ADDITIONAL STORMS WILL PROBABLY FORM FARTHER E IN N TX THIS EVENING
   AS ISENTROPIC ASCENT NOCTURNALLY STRENGTHENS ACROSS THE FRONT. LARGE
   HAIL...DAMAGING WINDS AND A TORNADIC SUPERCELL WILL BE POSSIBLE.

   FARTHER S/SE...GUIDANCE IS QUITE INSISTENT ON A WEAK IMPULSE
   EJECTING ACROSS PARTS OF S-CNTRL TX MIDDAY. WITH PERSISTENT
   LOW-LEVEL WAA AND BOUNDARY LAYER DESTABILIZATION AHEAD OF THIS...ANY
   ELEVATED CONVECTION SHOULD EVENTUALLY BECOME SURFACE-BASED. ALTHOUGH
   THE SURFACE PATTERN WILL LIKELY REMAIN NEBULOUS...SCATTERED STORMS
   MAY FORM BY LATE DAY. WITH SIMILARLY ELONGATED HODOGRAPHS...A FEW
   SUPERCELLS COULD DEVELOP WITH ALL SEVERE HAZARDS POSSIBLE. WHERE
   EXACTLY THIS OCCURS AND IT HOW EVOLVES E THIS EVENING/TONIGHT IS
   RATHER UNCERTAIN. THUS WILL MAINTAIN A BROAD-BRUSH SLIGHT RISK
   OUTLOOK FROM S-CNTRL TX ACROSS THE SABINE RIVER TO THE LOWER MS
   VALLEY.

   ...MID ATLANTIC STATES TO THE SRN APPALACHIANS...
   VERY LIMITED LOW-LEVEL MOISTURE IN THE WARM SECTOR WILL BE
   COMPENSATED BY ROBUST DIABATIC HEATING THAT SHOULD YIELD STEEP
   TROPOSPHERIC LAPSE RATES. ALTHOUGH BUOYANCY WILL BE MEAGER WITH
   MLCAPE LIKELY ONLY 100-300 J/KG...INVERTED-V THERMODYNAMIC PROFILES
   ARE EXPECTED. AN INTENSE MID-LEVEL JET WILL APPROACH FROM THE
   MIDWEST/CNTRL APPALACHIANS TO YIELD ELONGATED/STRAIGHT-LINE
   HODOGRAPHS. SCATTERED CONVECTION SHOULD FORM ALONG THE FRONT BY
   MID-AFTERNOON...THE MOST ROBUST OF WHICH SHOULD PRODUCE STRONG WIND
   GUSTS AND MARGINAL HAIL.