May 8, 2013 2000 UTC Day 1 Convective Outlook
Updated: Wed May 8 20:04:36 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20130508 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130508 2000 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
20130508 2000 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
20130508 2000 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
SLIGHT 113,830 3,355,306 Oklahoma City, OK...Wichita, KS...Norman, OK...Wichita Falls, TX...Salina, KS...
   SPC AC 082000
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0300 PM CDT WED MAY 08 2013
   
   VALID 082000Z - 091200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN CO...WRN AND CNTRL
   KS...WRN AND CNTRL OK INTO NWRN TX...
   
   ...ERN CO...WRN THROUGH CNTRL KS...WRN AND CNTRL OK AND NWRN TX...
   
   ONLY MINOR ADJUSTMENTS HAVE BEEN MADE FOR THIS UPDATE...MAINLY TO
   EXPAND SLIGHT RISK A LITTLE FARTHER WEST AND NORTH INTO ERN CO AND
   THE OK PANHANDLE TO ACCOUNT FOR STORMS DEVELOPING IN UPSLOPE REGIME
   AND SPREADING INTO THE HIGH PLAINS. OTHER STORMS SHOULD DEVELOP SWD
   ALONG DRYLINE ACROSS WRN OK INTO NWRN TX INTO THE EVENING. VERTICAL
   WIND PROFILES WITH 30-40 KT EFFECTIVE SHEAR SUPPORT ORGANIZED
   MULTICELLS AND SOME SUPERCELL STRUCTURES. DAMAGING WIND AND LARGE
   HAIL APPEAR TO BE THE PRIMARY THREATS. ACTIVITY MAY EVENTUALLY
   CONGEAL INTO ONE OR MORE CLUSTERS AS IT CONTINUES EWD THROUGH THE
   SRN PLAINS OVERNIGHT SUPPORTED BY A STRENGTHENING NOCTURNAL LLJ.
   
   ..DIAL.. 05/08/2013
   
   .PREV DISCUSSION... /ISSUED 1131 AM CDT WED MAY 08 2013/
   
   ...SYNOPSIS...
   MID-ATLANTIC UPR LOW IS EXPECTED TO DRIFT SLOWLY NNE INTO ERN PA BY
   THE END OF THE PERIOD...WHILE FOUR CORNERS SYSTEM REMAINS MORE OR
   LESS STNRY WHILE DEVOLVING INTO SEVERAL ELONGATED...PROGRESSIVE VORT
   MAXIMA. 
   
   AT THE SFC...LOOSELY-ORGANIZED LOW NOW CENTERED OVER SW KS/THE OK
   PANHANDLE SHOULD REMAIN NEARLY STNRY TODAY BEFORE EDGING E/SE ACROSS
   CNTRL KS/WRN OK AS AN ELONGATED AREA OF LOW PRESSURE TNGT/EARLY THU.
   IN THE EAST...DIFFUSE/MULTI-CENTERED LOW NOW OVER WV/MD IS EXPECTED
   TO DRIFT SLOWLY NNE WITH TIME...WITH LITTLE CHANGE IN STRENGTH.
    
   AN OUTFLOW BOUNDARY/WARM FRONT EXTENDING ESE FROM THE PLNS LOW...AND
   A LEE TROUGH/DRY LINE TRAILING SSW FROM IT...WILL BE THE MAIN FOCI
   FOR POTENTIAL SVR TSTM DEVELOPMENT THIS PERIOD. 
   
   ...CNTRL/SRN PLNS THIS AFTN THROUGH EARLY THU...
   WEAK TO LOCALLY MODERATE LARGE-SCALE ASCENT SHOULD CHARACTERIZE MUCH
   OF THE CNTRL AND SRN PLNS THIS PERIOD AS WEAK DISTURBANCES TRACK ENE
   WITH SE QUADRANT OF ELONGATING UPR LOW NOW OVER THE FOUR CORNERS. AT
   THE SAME TIME...AT LWR LVLS...PERSISTENT S-SSELY FLOW WILL MAINTAIN
   MODEST MOISTURE RETURN E OF DRY LINE AND S OF OUTFLOW BOUNDARY/WARM
   FRONT...WITH SFC DEWPOINTS EXPECTED TO RANGE FROM THE UPR 50S IN FAR
   SRN KS TO AROUND 60 F IN NW TX BY LATE IN THE DAY. 
   
   COMBINATION OF SLOWLY INCREASING MOISTURE...STRONG SFC
   HEATING...MODEST LARGE-SCALE ASCENT...AND CONVERGENCE ALONG SFC
   BOUNDARIES SHOULD PROMOTE DEVELOPMENT OF STRONG STORMS BY MID TO
   LATE AFTN AS SBCAPE INCREASES TO BETWEEN 1500 TO 2500 J/KG. OTHER
   STORMS MAY DEVELOP E/SE FROM THE HIGHER TERRAIN IN S CNTRL
   CO...WHERE LOW-LVL UPSLOPE FLOW WILL PERSIST N OF SFC LOW.
   
   30-35 KT WSWLY 500 MB FLOW ATOP 25 KT SLY LOW-LVL JET STREAM WILL BE
   FAVORABLE FOR SUSTAINED STORMS/SUPERCELLS. GIVEN THE THERMODYNAMIC
   ENVIRONMENT...THESE WILL YIELD BOTH LARGE HAIL AND LOCALLY DMGG
   WIND. TORNADOES MAY ALSO OCCUR...ALTHOUGH ANY SUCH OCCURRENCE LIKELY
   WILL BE TIED TO LOCALLY FAVORABLE STORM/BOUNDARY INTERACTIONS GIVEN
   SIZABLE TEMP-DEWPOINT SPREADS. 
   
   THE TSTMS LIKELY WILL EVOLVE INTO SEVERAL PERSISTENT CLUSTERS THIS
   EVE...WITH A CONTINUED RISK FOR SVR HAIL/WIND...GIVEN MULTIPLE
   SOURCES OF LOW-LVL ASCENT...ABSENCE OF A STRONG UPR-LVL FEATURE TO
   FOCUS DEVELOPMENT...AND INCREASING MOISTURE /PW TO 1.25 INCHES/. THE
   SVR THREAT SHOULD...HOWEVER...DECREASE WITH NOCTURNAL COOLING LATER
   TNGT.
   
   ...MID ATLANTIC THIS AFTN...
   COOL POCKET ALOFT ASSOCIATED WITH ERN STATE UPR LOW HAS SHRUNKEN
   RELATIVE TO RECENT DAYS AND NOW APPEARS TO BE CENTERED OVER MD/NRN
   VA. PART OF THIS FEATURE MAY PIVOT NWD INTO PA TODAY... WHERE IT
   WILL OVERSPREAD LINGERING CURRENT OF MOIST...ESELY LOW-LVL FLOW
   ALONG AND N OF WEAK OCCLUSION/SFC TROUGH. WITH SFC DEWPOINTS
   REMAINING IN THE UPR 50S TO AROUND 60F...AND WITH MODEST...LARGELY
   UNIDIRECTIONAL DEEP SELY FLOW CONTINUING...SETUP MAY YIELD A FEW
   INSTANCES OF MARGINALLY SVR HAIL...ESPECIALLY FROM CNTRL NJ AND THE
   NYC AREA WNW INTO CNTRL PA.
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z