Apr 27, 2014 0600 UTC Day 1 Convective Outlook
Updated: Sun Apr 27 06:23:43 UTC 2014 (20140427 1200Z Day 1 shapefile | 20140427 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20140427 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20140427 1200 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 1200 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 1200 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 116,964 9,157,610 Memphis, TN...Kansas City, MO...Shreveport, LA...Little Rock, AR...Overland Park, KS...
SLIGHT 315,605 19,800,704 Omaha, NE...Tulsa, OK...St. Louis, MO...Lincoln, NE...Des Moines, IA...
   SPC AC 270620

   DAY 1 CONVECTIVE OUTLOOK CORR 2
   NWS STORM PREDICTION CENTER NORMAN OK
   0120 AM CDT SUN APR 27 2014

   VALID 271200Z - 281200Z

   ...THERE IS A MDT RISK OF SVR TSTMS FROM EXTREME ERN KS...ERN
   OK...MUCH OF MO...AR...EXTREME NERN TX...WRN TN AND NWRN MS...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER ERN PORTIONS OF THE CNTRL
   AND SRN PLAINS THROUGH MUCH OF THE LOWER-MID MS VALLEY AND WRN TN
   VALLEY...

   CORRECTED FOR TEXT IN LAST PARAGRAPH...CATEGORICAL OUTLOOK GRAPHIC

   ...SUMMARY...
   NUMEROUS SEVERE STORMS WITH POTENTIAL FOR STRONG TORNADOES...VERY
   LARGE HAIL AND DAMAGING WIND ARE LIKELY ACROSS MUCH OF THE
   MISSISSIPPI RIVER VALLEY...WITH THE GREATEST THREAT FROM THE
   ARK-LA-TEX INTO ARKANSAS...WESTERN TENNESSEE AND WESTERN AND CENTRAL
   MISSOURI AND ERN KS. A SECONDARY THREAT AREA WILL BE FROM EASTERN
   NEBRASKA INTO IOWA...AND STORMS DEVELOPING IN THIS REGION DURING THE
   DAY WILL ALSO LIKELY PRODUCE LARGE HAIL AND SEVERAL TORNADOES.

   ...SYNOPSIS...

   VIGOROUS SHORTWAVE TROUGH WILL BE LOCATED ACROSS ERN WRN KS BY 12Z
   SUNDAY AND LIFT NEWD INTO NEB BY LATE SUNDAY AFTERNOON AND EVENING.
   A SECONDARY IMPULSE/JET MAX WILL ADVANCE THROUGH THE BASE OF THE
   UPPER TROUGH AND THROUGH THE SRN PLAINS...REACHING THE LOWER MS
   VALLEY REGION SUNDAY EVENING. AT THE SFC AN AREA OF LOW PRESSURE
   WILL DEEPEN AND LIFT NWD INTO NEB IN ASSOCIATION WITH THE PRIMARY
   SHORTWAVE TROUGH...WHILE A PACIFIC FRONT/DRYLINE SURGES EWD THROUGH
   THE CNTRL AND SRN PLAINS...REACHING THE MID MS VALLEY REGION BY
   EVENING. A WARM FRONT WILL EXTEND EWD FROM THE LOW AND LIFT NWD
   THROUGH NEB AND IA.

   ...EXTREME ERN PORTIONS OF CNTRL/SRN PLAINS THROUGH LOWER-MID MS AND
   TN VALLEYS...

   IT STILL APPEARS THAT MID-LEVEL CONVECTION MAY DEVELOP ABOVE THE CAP
   EARLY IN THE PERIOD ACROSS PORTIONS OF THE SRN PLAINS AND LOWER-MID
   MS VALLEY AREA. HOWEVER...THIS ACTIVITY IS EXPECTED TO SHIFT NEWD
   ALLOWING FOR UPSTREAM DESTABILIZATION. RICH GULF MOISTURE CURRENTLY
   RESIDES ACROSS ERN TX INTO LA AND WILL ADVECT NWD THROUGH THE
   LOWER-MID MS VALLEY WARM SECTOR WITH UPPER 60S DEWPOINTS AS FAR
   NORTH AS ARKANSAS AND MID 60S INTO MO BENEATH PLUME OF STEEP
   MID-LEVEL LAPSE RATES. THIS PROCESS WILL CONTRIBUTE TO AN AXIS OF
   MODERATE INSTABILITY WITH 1500-2000 J/KG MLCAPE EXPECTED BY MID
   AFTERNOON. HOWEVER...WIDESPREAD MULTILAYER CLOUDS SHOULD TEMPER
   BOUNDARY LAYER WARMING AND DESTABILIZATION TO SOME DEGREE.

   TWO AREAS OF SURFACE BASED THUNDERSTORM INITIATION APPEAR LIKELY
   INCLUDING ALONG THE DRYLINE/PACIFIC FRONT FROM ERN OK/ERN KS AS WELL
   AS FARTHER SOUTH WITHIN PRE-FRONTAL CONFLUENCE ZONE BY MID
   AFTERNOON...AS THE DIFFLUENT UPPER JET EXIT REGION OVERTAKES THE
   WARM SECTOR. DEEP LAYER WIND PROFILES WILL BECOME VERY FAVORABLE FOR
   SUPERCELLS WITH 0-6 KM SHEAR IN EXCESS OF 50 KT AND 0-1 KM STORM
   RELATIVE HELICITY FROM 200-300 J/KG. INITIAL STORMS ALONG THE
   DRYLINE AS WELL AS PRE-FRONTAL CONFLUENCE ZONE WILL LIKELY BE
   DISCRETE AND POSE A THREAT FOR VERY LARGE HAIL AND TORNADOES...A FEW
   OF WHICH COULD BE STRONG. SOME STORMS MAY EVENTUALLY CONSOLIDATE
   INTO ONE OR MORE MCSS DURING THE EVENING BUT WITH A CONTINUED THREAT
   FOR DAMAGING WIND...TORNADOES AND LARGE HAIL AS ACTIVITY DEVELOPS
   TOWARD THE TN VALLEY. A PORTION OF THE LOWER MS VALLEY MAY NEED TO
   BE INCLUDED IN A HIGH RISK IN LATER UPDATES.

   ...NEB AND IA...

   COOL TEMPERATURES ALOFT...STEEP LAPSE RATES AND MODEST LOW LEVEL
   MOISTURE WILL SUPPORT A NARROW AXIS OF MODERATE SURFACE BASED
   INSTABILITY IN VICINITY OF WARM FRONT ACROSS NEB INTO IA. FORCING
   FOR ASCENT ASSOCIATED WITH THE EJECTING SHORTWAVE TROUGH WILL
   INCREASE BY LATE MORNING SUPPORTING AN ARC OF STORMS IN VICINITY OF
   WARM FRONT. VEERING LOW-LEVEL WINDS WITH LARGE 0-2 KM HODOGRAPHS AND
   50 KT EFFECTIVE SHEAR WILL SUPPORT SUPERCELLS WITH TORNADOES AND
   LARGE HAIL AS ACTIVITY DEVELOPS NWD. MODERATE RISK MIGHT BE EXPANDED
   FARTHER NW TO INCLUDE A PORTION OF THIS AREA ON NEXT UPDATE.

   ..DIAL/LEITMAN.. 04/27/2014

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