May 7, 2015 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1259 AM CDT THU MAY 07 2015

   VALID 071200Z - 081200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL/SRN
   GREAT PLAINS...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE UPPER MS VALLEY TO THE
   SRN GREAT PLAINS...

   ...SUMMARY...
   ISOLATED TO SCATTERED SEVERE STORMS ARE POSSIBLE FROM THE UPPER
   MISSISSIPPI VALLEY TO THE SOUTHERN GREAT PLAINS...MAINLY THIS
   AFTERNOON AND EVENING.

   ...SYNOPSIS...
   BROAD UPPER TROUGH WILL REMAIN ANCHORED OVER THE PACIFIC COAST
   STATES WITH A VIGOROUS EMBEDDED IMPULSE DIGGING TOWARDS SRN CA. A
   SHORTWAVE TROUGH OVER THE NRN GREAT PLAINS SHOULD DAMPEN AS IT
   GRADUALLY SHIFTS INTO NWRN ONTARIO...WITH AN ATTENDANT SURFACE
   CYCLONE FOLLOWING A SIMILAR PATH. BETWEEN THESE FEATURES...SUBTLE
   MID-LEVEL IMPULSES MAY EJECT FROM AZ TO THE RIO GRANDE OF FAR W TX
   NEWD TOWARDS THE CNTRL HIGH PLAINS. A COLD FRONT WILL APPROACH THE
   UPPER MS VALLEY WITH TRAILING PORTION ACROSS THE MID-MO VALLEY
   BISECTING KS INTO ERN CO. THE DRYLINE SHOULD MIX E INTO THE TX S
   PLAINS AND ERN PERMIAN BASIN.

   ...SRN GREAT PLAINS...
   SOME PORTION OF THE CURRENT MCS ALONG THE RED RIVER MAY BE ONGOING
   AT 12Z. BOTH CONVECTION-ALLOWING AND CONVECTIVELY-PARAMETRIZED
   GUIDANCE ARE INSISTENT ON ADDITIONAL UPSTREAM CONVECTION BLOSSOMING
   OUT OF CURRENT ACCAS ACROSS THE WRN PERMIAN BASIN AHEAD OF A SUBTLE
   MID-LEVEL IMPULSE EVIDENT IN WATER VAPOR IMAGERY. THIS INITIAL
   ACTIVITY COMPLICATES THE OVERALL FORECAST SCENARIO WITH SUBSTANTIAL
   UNCERTAINTY REGARDING HOW THIS WILL EVOLVE DURING THE DAY AND MODIFY
   THE WARM SECTOR ENVIRONMENT. THE LEADING EDGE/SRN PORTION OF THE MCS
   MAY INTENSIFY AS DIURNAL HEATING ENSUES OVER THE BROAD PLUME OF
   MIDDLE TO UPPER 60S SURFACE DEW POINTS IN THE TX WARM SECTOR. A
   CLUSTER OF SEVERE HAIL/WIND AND A TORNADO OR TWO MAY ULTIMATELY
   EVOLVE DURING THE MORNING/AFTERNOON. FARTHER W ALONG THE
   DRYLINE...THE DEGREE OF LATE DAY STORM COVERAGE IS UNCERTAIN GIVEN
   THE PROBABLE EARLY DAY STORMS. STILL NEAR THE DRYLINE/CONVECTIVE
   OUTFLOW INTERSECTION...A QUITE FAVORABLE CAPE/SHEAR COMBINATION AND
   STEEP LAPSE RATES WOULD SUPPORT A RISK FOR A COUPLE SUPERCELLS
   CAPABLE OF VERY LARGE HAIL AND TORNADOES. GIVEN THE HIGHLY
   CONDITIONAL NATURE OF THIS SCENARIO...WILL REFRAIN FROM A SIG HAIL
   AREA THIS OUTLOOK.

   ...CNTRL GREAT PLAINS...
   N/W OF EXPECTED MORNING CONVECTION NEAR THE RED RIVER AND MID-MO
   VALLEY...DIABATIC HEATING SHOULD BECOME ROBUST AHEAD OF THE
   APPROACHING COLD FRONT. GIVEN THE DEGREE OF CONVECTIVE OVERTURNING
   ACROSS THE LOWER PLAINS ON WED INTO EARLY THU...SURFACE DEW POINTS
   WILL PROBABLY MIX INTO THE MIDDLE 40S TO MIDDLE 50S IN THE HIGH
   PLAINS. LOW-LEVEL UPSLOPE FLOW COUPLED WITH CONVERGENCE ALONG THE
   FRONT SHOULD YIELD INCREASING TSTM DEVELOPMENT FROM THE HIGH PLAINS
   INTO WRN KS BY LATE AFTERNOON/EARLY EVENING. ALTHOUGH LOWER-LEVEL
   WINDS MAY BE WEAK...DEEP-LAYER SHEAR WILL FAVOR A RISK OF LARGE HAIL
   AND SEVERE WIND GUSTS WITH PERHAPS A TORNADO OR TWO.

   ...UPPER MS VALLEY...
   WIDESPREAD EARLY-DAY CLOUD COVER FROM SCATTERED ONGOING CONVECTION
   NEAR THE MID-MO VALLEY INTO THE UPPER MIDWEST RENDERS UNCERTAINTY
   OVER THE DEGREE OF DIABATIC HEATING. IN ADDITION...GUIDANCE DIFFERS
   WITH THE EXTENT OF STEEPER LAPSE RATES ASSOCIATED WITH AN EML PLUME
   ADVANCING AHEAD OF THE NEWD-MOVING SHORTWAVE TROUGH OVER THE NRN
   PLAINS. WITH SUSTENANCE OF 30-45 KT LOW-LEVEL S/SWLYS...WHERE MODEST
   DESTABILIZATION CAN OCCUR WITHIN A PLUME OF MAINLY LOWER 60S F
   SURFACE DEWPOINTS...ISOLATED SEVERE HAIL/WIND AND A BRIEF TORNADO
   MAY DEVELOP NEAR AND E OF THE COLD FRONT. WILL CONTINUE DEFERENCE TO
   LATER OUTLOOKS FOR POSSIBLE SLIGHT RISK DELINEATION.