May 23, 2013 2000 UTC Day 1 Convective Outlook
Updated: Thu May 23 19:55:39 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20130523 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130523 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
20130523 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
20130523 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
MODERATE 14,360 84,267 Memphis, TX...Munday, TX...
SLIGHT 210,934 31,172,732 Philadelphia, PA...Baltimore, MD...Washington, DC...Lubbock, TX...Richmond, VA...
   SPC AC 231951
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0251 PM CDT THU MAY 23 2013
   
   VALID 232000Z - 241200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NWRN TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM
   WEST TX INTO THE NRN TX PANHANDLE...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID
   ATLANTIC INTO THE NORTHEAST...
   
   ...SOUTHERN PLAINS...
   
   HAVE MADE A FEW CHANGES TO 1630Z OUTLOOK ACROSS THE SRN PLAINS. 
   REMNANTS OF DECAYED MCS HAVE MIGRATED INTO THE ARKLATEX AND WEAK
   CONVERGENCE ALONG THE CONVECTIVE OUTFLOW BOUNDARY EXTENDS ACROSS
   NCNTRL TX WHERE TEMPERATURES HAVE WARMED INTO THE MID 80S.  ALTHOUGH
   SIGNIFICANT MOISTURE/INSTABILITY RESIDE ACROSS THIS REGION THERE IS
   LESSENING CONFIDENCE LOW LEVEL CONVERGENCE WILL PROVE SUFFICIENT FOR
   MORE THAN A FEW TSTMS LATER TODAY.
   
   ANOTHER AREA WHERE PROBABILITIES HAVE BEEN ADJUSTED ARE ACROSS THE
   BIG BEND REGION OF WEST TX.  TSTMS HAVE RECENTLY DEVELOPED AND ARE
   INTENSIFYING WITHIN MOIST SELY LOW LEVEL FLOW.  WHILE DEEP LAYER
   SHEAR IS NOT PARTICULARLY STRONG...FLOW APPEARS ADEQUATE TO WARRANT
   AT LEAST SLOW MOVING ORGANIZED MULTI-CELLS CAPABLE OF PRODUCING
   LARGE HAIL.
   
   FARTHER NORTH ACROSS THE MDT RISK...WWD MOVING OUTFLOW IS SURGING
   ACROSS THE PANHANDLE AND SHOULD STALL SOON.  STRONG HEATING NEAR THE
   WIND SHIFT AND FAVORABLE UPSLOPE FLOW WILL LIKELY CONTRIBUTE TO
   SIGNIFICANT TSTM DEVELOPMENT OVER THE NEXT FEW HOURS.  LATEST VIS
   IMAGERY SUPPORTS THIS WITH TOWER CU NEAR/JUST WEST OF THE I-27
   CORRIDOR.  AFTER INITIAL SUPERCELL DEVELOPMENT ONE OR MORE MCS/S
   SHOULD EVOLVE OVER THE SOUTH PLAINS WITH SUBSEQUENT PROPAGATION
   EXPECTED INTO PORTIONS OF NWRN TX.
   
   ...MID ATLANTIC STATES INTO THE NORTHEAST...
   
   ONLY MINOR CHANGES HAVE BEEN MADE TO EARLIER PROBABILITIES...NAMELY
   TO EXTEND 2 PERCENT TORNADO PROBS SOUTHWARD ACROSS THE DELMARVA TO
   ACCOUNT FOR WEAK SUPERCELL STRUCTURES OVER THIS REGION.
   
   ..DARROW.. 05/23/2013
   
   .PREV DISCUSSION... /ISSUED 1120 AM CDT THU MAY 23 2013/
   
   ...SYNOPSIS...
   WHILE THE CURRENT BLOCKING PATTERN OVER NORTH AMERICA IS EXPECTED TO
   BECOME A BIT LESS PROMINENT...LARGE-SCALE MID/UPPER FLOW OVER THE
   U.S. IS EXPECTED TO REMAIN AMPLIFIED AND SLOW TO CHANGE.  IN THE
   EAST...THE TRANSITION OF A CLOSED LOW TO AN OPEN WAVE TROUGH
   CONTINUES ACROSS THE GREAT LAKES AND LOWER OHIO VALLEY REGION...TO
   THE SOUTH OF A SHORT WAVE TROUGH SLOWLY DIGGING SOUTHEAST OF THE
   HUDSON/JAMES BAY REGION.  BOTH THESE FEATURES WILL CONTINUE TO
   GRADUALLY TURN EASTWARD/SOUTHEASTWARD TOWARD THE ATLANTIC SEABOARD
   LATER TODAY AND TONIGHT.  AT THE SAME TIME...A DEEP MID-LEVEL CLOSED
   LOW WILL LINGER OVER THE PACIFIC NORTHWEST...WITH BROADER SCALE
   UPPER TROUGHING ENCOMPASSING MUCH OF THE PACIFIC COAST STATES INTO
   THE ROCKIES.  A SIGNIFICANT MID-LEVEL IMPULSE IS EXPECTED TO
   CONTINUE TO GRADUALLY PIVOT AROUND THE LOW...ACROSS THE NORTHERN
   GREAT BASIN INTO THE NORTHERN ROCKIES BY LATE TONIGHT.  THIS WILL
   SUPPRESS MID-LEVEL HEIGHT RISES ACROSS PARTS OF THE NORTHERN
   PLAINS...WHILE MID/UPPER RIDGING REMAINS OR BECOME MORE PROMINENT
   ACROSS MUCH OF THE PLAINS INTO THE MISSISSIPPI VALLEY REGION.  A
   COUPLE OF WEAK IMPULSES PROGRESSING THROUGH THE CYCLONIC FLOW ACROSS
   THE SOUTHERN PLATEAU INTO THE SOUTHERN ROCKIES REGION MAY HAVE AT
   LEAST A GLANCING IMPACT ON PARTS OF THE SOUTHERN PLAINS...HOWEVER.
   
   ...MID ATLANTIC STATES INTO THE NORTHEAST...
   AHEAD/EAST OF A COLD FRONT ADVANCING ACROSS THE LOWER GREAT LAKES
   AND OHIO VALLEY REGION...MID-LEVEL LAPSE RATES APPEAR TO HAVE
   STABILIZED CONSIDERABLY OVER THE PAST COUPLE OF DAYS.  CONSIDERABLE
   CLOUD COVER AND PRECIPITATION...SOME CONVECTIVE...IS ALREADY WELL
   UNDERWAY...AND IT IS NOT CLEAR HOW MUCH DESTABILIZATION WILL TAKE
   PLACE TODAY.  THERE ARE BREAKS IN CLOUD COVER...WHICH WILL ALLOW FOR
   AT LEAST POCKETS OF HEATING AND WEAK TO MODEST DESTABILIZATION...THE
   STRONGEST OF WHICH SEEMS LIKELY TO TAKE PLACE ALONG THE LEE SURFACE
   TROUGH...EAST OF THE APPALACHIANS.  THIS MAY INCLUDE THE URBAN
   CORRIDOR FROM WASHINGTON D.C./BALTIMORE INTO THE PHILADELPHIA AREA.
   
   WHERE SUBSTANTIVE DESTABILIZATION IS ABLE TO TAKE PLACE...SHEAR AND
   MOMENTUM ASSOCIATED WITH 20-40 KT SOUTHWESTERLY LOWER/MID
   TROPOSPHERIC FLOW MAY ENHANCE CONVECTIVE DEVELOPMENT... CONTRIBUTING
   TO STORM MOTION AND ORGANIZATION.  STRONGEST ACTIVITY MAY BE CAPABLE
   OF PRODUCING SEVERE WIND GUSTS...WITH SOMEWHAT LOWER POTENTIAL FOR
   SEVERE HAIL OR A TORNADO.
   
   ...SOUTHERN PLAINS...
   THE SEVERE STORM/SMALL STORM CLUSTER THAT EVOLVED FROM A LARGER
   SCALE WARM ADVECTION REGIME OVER CENTRAL OKLAHOMA EARLIER THIS
   MORNING IS CURRENTLY WEAKENING SOUTH OF THE RED RIVER...ACROSS PARTS
   OF NORTHEAST TEXAS.  IT MAY NOT BE OUT OF THE QUESTION THAT REMNANTS
   OF THIS ACTIVITY COULD BE ASSOCIATED WITH NEW INTENSE STORM
   DEVELOPMENT ACROSS PARTS OF EASTERN TEXAS INTO LOUISIANA LATER
   TODAY...IN THE PRESENCE OF POTENTIALLY STRONG INSTABILITY. 
   HOWEVER...THE PRIMARY CONVECTIVE POTENTIAL IS EXPECTED TO BECOME
   FOCUSED NEAR THE DRYLINE AND A DEVELOPING WARM FRONT ACROSS THE
   SOUTHERN HIGH PLAINS LATER THIS AFTERNOON AND EVENING.
   
   DESPITE THE TENDENCY FOR CONTINUING WEAK MID-LEVEL HEIGHT RISES
   ACROSS THE SOUTHERN PLAINS TODAY...MODELS SUGGEST CONVECTIVE
   INHIBITION WILL WEAKEN SUFFICIENTLY BY PEAK AFTERNOON HEATING FOR
   STORM INITIATION ON THE DRYLINE.  THE MOST INTENSE STORMS/GREATEST
   STORM COVERAGE IS EXPECTED NEAR THE DRYLINE/WARM FRONT
   INTERSECTION...EAST/SOUTHEAST OF LUBBOCK AND AMARILLO INTO AREAS OF
   NORTHWEST TEXAS NEAR/SOUTH OF CHILDRESS.  THIS IS WHERE
   THERMODYNAMIC PROFILES WITH VERY STEEP MID-LEVEL LAPSE RATES AND
   LARGE CAPE SHOULD BE SUPPORTIVE OF SUPERCELLS...BEFORE CONSIDERABLE
   UPSCALE GROWTH OCCURS BY EARLY EVENING.
   
   VERY LARGE HAIL IS POSSIBLE IN STRONGEST CELLS.  A COUPLE OF
   TORNADOES ARE ALSO POSSIBLE...BUT TORNADIC POTENTIAL MAY BE HINDERED
   BY WEAKNESS IN MID-LEVEL FLOW...AND A TENDENCY FOR STORMS TO QUICKLY
   GENERATE CONSIDERABLE OUTFLOW.
   
   ...NORTHERN ROCKIES...
   ALTHOUGH MOISTURE APPEARS TO REMAIN LIMITED ACROSS THE BASINS
   WEST/SOUTH OF THE LARAMIE AND BIG HORN MOUNTAINS OF WYOMING... THE
   ENVIRONMENT APPEARS AT LEAST MARGINALLY CONDUCIVE TO ISOLATED
   SUPERCELL DEVELOPMENT LATE THIS AFTERNOON/EVENING...SOME OF WHICH
   COULD DEVELOP/SPREAD NORTH/EAST OF THE MOUNTAINS INTO PARTS OF
   EASTERN WYOMING AND MONTANA.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z