Apr 27, 2014 1300 UTC Day 1 Convective Outlook
Updated: Sun Apr 27 12:54:39 UTC 2014 (20140427 1300Z Day 1 shapefile | 20140427 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting zczc spcpwospc all wous40 kwns 270646 arz000-ksz000-laz000-moz000-msz000-okz000-tnz000-txz000-271800- public severe weather outlook nws storm prediction center norman ok 0146 am cdt sun apr 27 2014 * locations....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20140427 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20140427 1300 UTC Day 1 Tornado Probabilities Graphic
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.
Probabilistic Damaging Wind Graphic
20140427 1300 UTC Day 1 Damaging Wind Probabilities Graphic
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.
Probabilistic Large Hail Graphic
20140427 1300 UTC Day 1 Large Hail Probabilities Graphic
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.
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 119,987 9,218,833 Memphis, TN...Kansas City, MO...Shreveport, LA...Little Rock, AR...Overland Park, KS...
SLIGHT 343,752 27,689,207 Dallas, TX...Ft. Worth, TX...Omaha, NE...Tulsa, OK...Wichita, KS...
   SPC AC 271251

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0751 AM CDT SUN APR 27 2014

   VALID 271300Z - 281200Z

   ...THERE IS A MDT RISK OF SVR TSTMS OVER FAR ERN PARTS OF
   KS/OK...NERN TX...AR...WRN/CNTRL/SRN MO...NWRN MS AND WRN TN...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MO VALLEY TO ERN
   TX AND THE LOWER MS VALLEY...

   ...SUMMARY...
   WIDESPREAD SEVERE THUNDERSTORMS CAPABLE OF TORNADOES...VERY LARGE
   HAIL AND DAMAGING WINDS ARE LIKELY FROM THE MIDDLE AND LOWER
   MISSOURI VALLEY SOUTH THROUGH THE OZARKS INTO LOWER MISSISSIPPI
   VALLEY THIS AFTERNOON INTO TONIGHT. THE GREATEST RISK FOR A FEW
   INTENSE TORNADOES WILL EXIST ACROSS MUCH OF ARKANSAS PERHAPS INTO
   WESTERN AND CENTRAL MISSOURI THIS AFTERNOON INTO TONIGHT.

   ...SYNOPSIS...

   A POWERFUL SHORT-WAVE TROUGH AND ASSOCIATED 70-80 KT MIDLEVEL JET
   STREAK WILL TRANSLATE FROM THE CNTRL/SRN HIGH PLAINS INTO THE UPPER
   MIDWEST WITH THE SYSTEM CLOSING OFF AN UPPER LOW OVER THE CNTRL
   PLAINS. ON THE HEELS OF THE INITIAL SHORT-WAVE TROUGH...A CHANNELED
   VORTICITY MAXIMUM AND ATTENDANT 70+ KT JET STREAK AT 500 MB WILL
   PROGRESS THROUGH THE SRN PLAINS INTO THE OZARK PLATEAU BY TONIGHT.
   IN RESPONSE TO THIS UPPER-AIR PATTERN EVOLUTION...A 40-50+ KT SLY
   LLJ WILL MIGRATE FROM ERN PARTS OF THE GREAT PLAINS INTO MS
   VALLEY...ENHANCING THE POLEWARD FLUX OF HEAT AND MOISTURE THROUGH
   THE WARM SECTOR OF THE SYNOPTIC CYCLONE.  

   AT THE SURFACE...A LEE CYCLONE OVER SWRN NEB WILL GRADUALLY FILL AS
   IT SLOWLY DEVELOPS ENEWD INTO ERN NEB BY 28/12Z. A TRAILING PACIFIC
   FRONT WILL SURGE EWD THROUGH THE CNTRL PLAINS INTO OZARKS/OZARK
   PLATEAU WITH THE SRN EXTENSION OF THE FRONT MOVING MORE SLOWLY EWD
   THROUGH CNTRL INTO ERN TX. MEANWHILE...A WARM FRONT WILL STEADILY
   MOVE NWD THROUGH THE LOWER/MID MO AND MID MS VALLEYS.

   ...SRN PLAINS INTO THE LOWER MS VALLEY THIS MORNING THROUGH
   TONIGHT...

   TSTMS HAVE RECENTLY DEVELOPED ALONG AND JUST AHEAD OF THE PACIFIC
   FRONT OVER OK/N TX ALONG THE SRN FRINGE OF STRONGER HEIGHT
   FALLS/DCVA ATTENDANT TO THE SHORT-WAVE PROGRESSING NEWD INTO THE
   CNTRL PLAINS. THESE STORMS ARE LIKELY SLIGHTLY ELEVATED AND ROOTED
   WITHIN A MOIST WARM CONVEYOR BELT AIR STREAM WHICH COINCIDES WITH
   STEEP MIDLEVEL LAPSES AND MUCAPE OF 2000-2500 J/KG. AREA VAD DATA
   INDICATE A VEER-BACK SIGNATURE WITH HEIGHT WHICH SHOULD YIELD
   COMPLEX STORM MODES CAPABLE OF MAINLY LARGE HAIL AND LOCALLY
   DAMAGING WINDS AS ACTIVITY SHIFTS NEWD THIS MORNING.

   A SUBSET OF THE ONGOING STORMS WILL LIKELY BECOME SURFACE-BASED BY
   LATE MORNING INTO AFTERNOON OVER ERN OK INTO NERN TX WITH OTHER IN
   SITU STORM DEVELOPMENT ALONG THE FRONT. ADDITIONAL TSTMS ARE
   ANTICIPATED BY AFTERNOON AHEAD OF THE FRONT FROM THE ARKLATEX NEWD
   ACROSS AR...IN THE WAKE OF THE MORNING ELEVATED STORMS. BOTH THESE
   REGIMES WILL BE ENCOURAGED BY THE ARRIVAL OF THE NEXT MIDLEVEL JET
   STREAK PROPAGATING THROUGH THE RED RIVER VALLEY.

   THE COMBINATION OF MODERATE INSTABILITY AND RELATIVELY STRONG
   VERTICAL SHEAR WILL PROMOTE A MIXTURE OF SUPERCELL AND BOWING
   STRUCTURES CAPABLE OF TORNADOES...VERY LARGE HAIL AND DAMAGING
   WINDS. THE MOST FAVORABLE ENVIRONMENT FOR LONG-LIVED SUPERCELLS AND
   MULTIPLE INTENSE TORNADOES WILL LIKELY MATERIALIZE OVER AR TOWARD
   THE DELTA REGION OF NWRN MS LATER THIS AFTERNOON INTO TONIGHT.
   HERE...MLCAPE OF 2000-2500 J/KG WILL ALIGN WITH EFFECTIVE SRH OF
   250-350 M2/S2 AND 50-60 KT OF DEEP-LAYER SHEAR TO CREATE A VERY
   FAVORABLE ENVIRONMENT FOR UPDRAFT ROTATION. AN UPGRADE TO A
   CATEGORICAL HIGH RISK REMAINS POSSIBLE OVER THIS AREA LATER TODAY.

   ...NEB/KS EWD INTO MID MS VALLEY LATE THIS MORNING INTO TONIGHT...

   ELEVATED TSTMS HAVE GRADUALLY INCREASED IN COVERAGE EARLY THIS
   MORNING OVER THE CNTRL PLAINS ALONG THE LEADING EDGE OF HEIGHT FALLS
   ATTENDANT TO THE HIGH PLAINS SHORT-WAVE TROUGH...AND ROOTED WITHIN A
   BELT OF ISENTROPIC ASCENT ALONG THE NOCTURNAL LLJ. THIS ACTIVITY MAY
   CONTINUE TO INCREASE IN AREAL COVERAGE THIS MORNING WHILE MOVING
   NEWD INTO THE MID AND LOWER MO VALLEY. LARGE HAIL AND LOCALLY
   DAMAGING WIND GUSTS WILL BE THE PRIMARY HAZARDS WITH THESE STORMS.

   UNCERTAINTY IN DEGREE OF AFTERNOON DESTABILIZATION HAS INCREASED
   OVER THE LAST COUPLE OF HOURS OWING TO THE GROWING EXTENT OF
   ELEVATED TSTMS. WHERE BREAKS IN THE CLOUDS CAN OCCUR...CONTINUED
   BOUNDARY LAYER MOISTENING COUPLED WITH STRONG COOLING ALOFT WILL
   PROMOTE MLCAPE APPROACHING 1000-2000 J/KG. WHEN COUPLED WITH
   VERTICALLY VEERING WIND PROFILES AND 40-50 KT OF DEEP-LAYER
   SHEAR...THE ENVIRONMENT WILL BE SUPPORTIVE OF A MIXTURE OF BOWING
   AND SUPERCELL STRUCTURES CAPABLE OF TORNADOES /SOME POSSIBLY
   STRONG/...VERY LARGE HAIL AND DAMAGING WINDS. THE POTENTIAL FOR
   ISOLATED TORNADOES WILL EXIST AS FAR W/SW AS WRN NEB/NERN CO/NWRN KS
   INVOF THE DEEP-LAYER CYCLONE WHERE STEEP LAPSE RATES WILL COINCIDE
   WITH HIGH AMBIENT VERTICAL VORTICITY.

   BY THIS EVENING INTO TONIGHT...TSTMS MAY CONSOLIDATE INTO CLUSTERS
   OR A QLCS WITH THE RISK FOR PRIMARILY DAMAGING WINDS AND HAIL
   SPREADING EWD INTO THE MID MS VALLEY.

   ..MEAD/MOSIER.. 04/27/2014

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