Apr 17, 2013 0600 UTC Day 1 Convective Outlook
Updated: Wed Apr 17 06:04:32 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20130417 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130417 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
20130417 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
20130417 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 67,668 4,111,385 Oklahoma City, OK...Tulsa, OK...Norman, OK...Wichita Falls, TX...Broken Arrow, OK...
SLIGHT 243,568 30,460,754 Chicago, IL...Dallas, TX...Ft. Worth, TX...Kansas City, MO...Wichita, KS...
   SPC AC 170600
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0100 AM CDT WED APR 17 2013
   
   VALID 171200Z - 181200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NORTH TX AND OK
   TO EASTERN KS/SOUTHWEST MO...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SOUTHERN PLAINS TO THE
   LOWER MO VALLEY/MIDWEST...
   
   ...SYNOPSIS...
   A PROMINENT/NEUTRAL TO SLIGHT POSITIVE-TILT UPPER TROUGH OVER THE
   WESTERN CONUS WILL CONTINUE EASTWARD TODAY FROM THE GREAT BASIN/
   ROCKIES TO THE HIGH PLAINS...WITH PHASED POLAR/SUBTROPICAL JETS
   INCREASINGLY INFLUENCING THE CENTRAL/SOUTHERN PLAINS INTO THIS
   AFTERNOON/TONIGHT. SURFACE CYCLOGENESIS IS EXPECTED ACROSS THE
   SOUTHERN HIGH PLAINS...WITH AN EASTWARD MIXING DRYLINE ACROSS
   NORTHWEST/WEST-CENTRAL TX. NORTHEASTWARD FROM THE SURFACE LOW...A
   SURFACE FRONTAL ZONE WILL ONLY MOVE SLOWLY ACROSS OK/NORTHWEST TX
   THROUGH THE AFTERNOON...WITH A MUCH MORE AGGRESSIVE NORTHWARD PUSH
   AS A WARM FRONT ACROSS THE LOWER MO VALLEY/MIDWEST THROUGH TONIGHT
   IN RESPONSE TO LATE PERIOD SURFACE CYCLOGENESIS.
   
   ...SOUTHERN PLAINS TO LOWER MO VALLEY/MIDWEST...
   WELL-ABOVE TYPICAL GUIDANCE SPREAD CONTINUES INTO THE DAY 1
   PERIOD...ACCENTUATED BY A MUCH MORE NORTHWARD AND SEEMINGLY LESS
   LIKELY SOLUTION OF THE 00Z GFS AS COMPARED TO THE 00Z NAM/12Z ECMWF.
   AMONG OTHER UNCERTAINTIES...THIS IS A FACTOR FOR ONLY MODEST
   CONFIDENCE IN SPECIFIC DETAILS LATER TODAY. EVEN SO...POTENTIALLY
   WIDESPREAD/MULTI-FACETED SEVERE WEATHER IS LIKELY ESPECIALLY INTO
   THIS AFTERNOON/EVENING.
   
   INITIALLY...ELEVATED STRONG/POTENTIALLY SEVERE TSTMS CAPABLE OF HAIL
   WILL LIKELY BE ONGOING THIS MORNING ACROSS PORTIONS OF THE
   LOWER/MIDDLE MO VALLEY AND ADJACENT MIDWEST. THIS WILL BE IN
   ASSOCIATION WITH A STRONG LOW LEVEL JET/WARM ADVECTION REGIME.
   
   FARTHER SOUTH...A MORE WIDESPREAD/SURFACE BASED TSTM THREAT WILL
   LIKELY EVOLVE AS EARLY AS THIS AFTERNOON...BUT ESPECIALLY INTO THIS
   EVENING/TONIGHT ACROSS THE SOUTHERN PLAINS TO THE LOWER MO VALLEY IN
   GENERAL VICINITY OF AFOREMENTIONED FRONTAL ZONE. WHILE NOT
   NECESSARILY LIKELY...THERE MAY BE SOME POSSIBILITY THAT TSTMS
   DEVELOP RELATIVELY EARLY IN THE AFTERNOON ACROSS PORTIONS OF NORTH
   TX INTO EASTERN OK AND PERHAPS EVEN THE OZARKS...AND POTENTIALLY
   BECOME SURFACE BASED WITHIN AN INCREASINGLY MOIST/UNINHIBITED
   BOUNDARY LAYER. SHOULD THIS OCCUR...DISCRETE SUPERCELLS CAPABLE OF
   LARGE HAIL/TORNADOES WOULD BE POSSIBLE.
   
   SURFACE BASED DEVELOPMENT DOES SEEM MORE PROBABLE NEAR THE TRIPLE
   POINT VICINITY OF DRYLINE/COMPOSITE FRONT...UNDER THE INFLUENCE OF A
   BIT STRONGER HEATING/MASS CONVERGENCE. THIS WOULD BE ACROSS PARTS OF
   NORTH-CENTRAL/NORTHWEST TX INTO SOUTHWEST/SOUTH-CENTRAL OK.
   ESPECIALLY GIVEN AN INTENSIFYING LOW LEVEL JET TOWARD/AFTER
   DARK...POTENTIAL WOULD EXIST FOR LARGE HAIL AND PERHAPS A FEW STRONG
   TORNADOES ACROSS THIS REGION.
   
   OTHERWISE...STORMS ARE EXPECTED TO INCREASE AFTER DARK IN VICINITY
   OF THE SOUTH-SOUTHWEST TO NORTH-NORTHEAST ORIENTED FRONTAL ZONE
   ACROSS OK INTO THE LOWER MO VALLEY AND EVENTUALLY MIDDLE MS VALLEY
   MIDWEST. SOME POTENTIAL FOR SURFACE BASED TSTMS/SUPERCELLS AND
   ASSOCIATED DAMAGING WIND/TORNADO POTENTIAL WILL EXIST MAINLY THROUGH
   THE EVENING IMMEDIATELY NEAR THE FRONT...BUT THERE WILL LIKELY BE A
   TENDENCY FOR UPDRAFTS TO BE UNDERCUT BY THE NOCTURNALLY
   SOUTH/SOUTHEASTWARD-ACCELERATING COLD FRONT. AS SUCH...LARGE HAIL
   MAY BECOME THE MOST PROBABLE/MORE WIDESPREAD CONCERN ACROSS THE
   REGION.
   
   ...TN VALLEY TO CENTRAL/SOUTHERN APPALACHIANS...
   AT LEAST ISOLATED TO WIDELY SCATTERED TSTMS ARE EXPECTED TO
   DIURNALLY INCREASE THIS AFTERNOON ACROSS THE REGION. WHILE FORCING
   ON THE LARGE SCALE WILL BE MODEST AND MID-LEVEL LAPSE RATES/VERTICAL
   SHEAR WILL BE WEAK...STEEPENING LOW LEVEL LAPSE RATES DURING THE
   AFTERNOON MAY CONTRIBUTE TO SOME POTENTIAL FOR EPISODIC BOUTS OF
   LOCALLY DAMAGING WINDS/HAIL.
   
   ..GUYER/MOSIER.. 04/17/2013
   
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