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May 22, 2005 1300 UTC Day 1 Convective Outlook
Updated: Sun May 22 12:46:11 UTC 2005  (Print Version)
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 Forecast Discussion
   SPC AC 221242
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0742 AM CDT SUN MAY 22 2005
   
   VALID 221300Z - 231200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 70 WNW
   ANJ PLN DTW CMH HTS JKL LOZ BNA MEM HOT 40 S MLC FSI CSM GAG P28 25
   NNW JLN TBN BLV MTO LAF SBN MKG MQT.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 S SAV 40 SSE CSG
   45 NW JAN 40 NNW MWL 15 N BGS INK 65 SSW MRF ...CONT... 20 NW ELP 15
   SW 4CR 10 N ABQ 30 SSE GUC 25 WSW 4FC 40 SW LAR 15 NE DGW 50 WNW CDR
   25 SW CDR 25 NNW SNY 10 NW GLD 55 NW GCK 15 ESE SLN 25 ENE SZL 45
   WNW STL 20 W SPI 25 E PIA 10 WSW JVL 30 NNE RHI 40 W CMX 80 NNW CMX
   ...CONT... 50 ESE MTC 15 SW CAK 45 E LYH 10 E ORF.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM SRQ 30 S AGR MIA.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM  MI AND THE LWR OH VLY SW
   INTO THE OZARKS/SRN PLNS...
   
   ...SYNOPSIS...
   POTENT UPPER IMPULSE WHICH CRESTED SWRN STATES RIDGE YESTERDAY IS
   NOW CENTERED NEAR INL. SYSTEM HAS LIKELY REACHED MAXIMUM INTENSITY
   AND SHOULD DEAMPLIFY AS IT SHEARS SE ACROSS THE WI LATER TODAY IN
   RESPONSE TO CONTINUING PRESENCE OF NRN QUEBEC BLOCK.  FARTHER W...
   STRONG UPSTREAM SYSTEM NOW NEARING VANCOUVER ISLAND SHOULD CONTINUE
   E INTO AB/SASK...SERVING TO FURTHER FLATTEN SWRN RIDGE.
   
   AT LWR LEVELS...COLD/OCCLUDED FRONT NOW CROSSING THE UPR GRT LKS
   SHOULD WEAKEN AS IT CONTINUES SE ACROSS THE OH VLY.  SWRN PART OF
   SAME BOUNDARY SHOULD DECELERATE AND BECOME NEARLY STATIONARY OVER
   SRN PARTS OF AR AND OK BY 12Z MONDAY.
   
   ...SRN PLNS/OZARKS...
   TSTMS NOW OVER SRN MO/NRN AR ARE ASSOCIATED WITH A NARROWING ZONE OF
   WARM ADVECTION ASSOCIATED WITH WLY BRANCH OF LLJ.  THIS ACTIVITY
   SHOULD DISSIPATE AS THE JET WEAKENS A BIT LATER THIS MORNING.
   
   IN WAKE OF MORNING STORMS...CONSIDERABLE INSTABILITY /AVERAGE MLCAPE
   TO 2500 J PER KG/ WILL DEVELOP INVOF WEAKENING FRONT SETTLING S INTO
   THE SRN PLNS AND NRN OZARKS THIS AFTERNOON.  SATELLITE LOOPS SHOW NO
   APPARENT SMALL SCALE IMPULSE UPSTREAM TO ENHANCE FORCING FOR ASCENT.
    BUT COMBINATION OF HEATING AND FRONTAL CONVERGENCE SHOULD BE
   SUFFICIENT TO BREAK STRONG CAP AND INITIATE A FEW SURFACE-BASED
   STORMS OVER NRN OK...NRN AR AND SW MO LATE THIS AFTERNOON. 
   ADDITIONAL STORMS MAY FORM ALONG STORM GUST FRONTS AS THE BOUNDARIES
   MOVE GENERALLY S/SE INTO TONIGHT.
   
   WHILE MID LEVEL NNW FLOW WILL BE MODEST ON EDGE OF STRONG UPPER
   RIDGE ...AMPLE /30-35 KT/ DEEP SHEAR SHOULD BE PRESENT FOR SUSTAINED
   SUPERCELLS...ESPECIALLY IN AR/MO.  STEEP BOUNDARY LAYER LAPSE RATES
   AND FAIRLY LARGE TEMPERATURE/DEW POINT SPREADS SHOULD SUPPORT
   OUTFLOW-DOMINANT STORMS WITH HIGH WIND AND LARGE HAIL. THE ACTIVITY
   MAY MERGE INTO ONE OR TWO MCSS THIS EVENING.  LOW LEVEL INFLOW INTO
   THE CONVECTIVE SYSTEMS WILL REMAIN MODEST...BUT WILL PROBABLY BE
   SUFFICIENT TO EXTEND A LIMITED THREAT FOR HIGH WIND/HAIL SE ALONG
   PERIPHERY OF CAP INTO NRN MS BY EARLY MONDAY.
   
   ...GRT LKS/LWR OH VLY INTO SE MO...
   MORE MODEST INSTABILITY WILL DEVELOP THIS AFTERNOON AHEAD OF FRONT
   CROSSING MI IL/IND AND WRN KY. AFTERNOON MLCAPE VALUES SHOULD RANGE
   FROM AROUND 500 J/KG IN MI TO AROUND I500 J/KG IN SRN IL/WRN IND. 
   THESE VALUES ARE CERTAINLY SUPPORTIVE OF SEVERE STORMS GIVEN A
   SUFFICIENT DEGREE OF UPLIFT.  CONSIDERABLE UNCERTAINTY EXISTS
   REGARDING THE LATTER POINT.
   
   WITH THE COLD/OCCLUDED FRONT CROSSING THE REGION LIKELY TO WEAKEN
   THROUGH THE DAY...THE MAIN SOURCE OF FORCING FOR ASCENT WILL BE LOBE
   OF VORTICITY WELL DEPICTED IN SATELLITE IMAGERY ATTM CROSSING CNTRL
   WI.  EXTRAPOLATION OF CURRENT SATELLITE TRENDS...AND GFS
   GUIDANCE...SUGGEST THAT STRONGEST DCVA WILL REMAIN CONFINED TO MI
   AND NRN IND.  POINTS FARTHER SW SHOULD REMAIN ON ANTICYCLONIC SIDE
   OF UPPER JET...ALTHOUGH UPPER FLOW WILL BE SOMEWHAT DIFFLUENT.
   
   SHEAR PROFILES WILL BE FAVORABLE FOR DISCRETE SUPERCELLS THROUGHOUT
   THE REGION...ESPECIALLY FROM SRN MI INTO SRN IL/IND/SE MO...WHERE
   40-50 KT DEEP NWLY SHEAR WILL BE ORIENTED PERPENDICULAR TO SURFACE
   FRONT. WEAK LARGE SCALE FORCING FOR ASCENT AND CLOUDINESS MAY LIMIT
   CONVECTIVE COVERAGE.  BUT OVERALL SETUP SUPPORTS FORECAST OF AT
   LEAST A CONDITIONAL THREAT FOR SUSTAINED SEVERE THIS AFTERNOON INTO
   EARLY TONIGHT.
   
   ...FRONT RANGE...
   WIDELY SCATTERED STORMS SHOULD FORM LATE THIS AFTERNOON THROUGH THIS
   EVENING IN ZONE OF OROGRAPHIC UPLIFT/STRONG HEATING ALONG THE FRONT
   RANGE OF THE CNTRL RCKYS.  DEEP SHEAR WILL DECREASE FROM SRN WY INTO
   SRN CO/NRN NM...BUT SHOULD BE SUFFICIENT THROUGHOUT REGION FOR
   ORGANIZED ACTIVITY INCLUDING A FEW SUPERCELLS. ACTIVITY WILL LIKELY
   BE HIGH BASED...PROMOTING A FEW STRONG TO SEVERE GUSTS AND PERHAPS
   MARGINALLY SEVERE HAIL.
   
   ...N GA/WRN CAROLINAS...
   A FEW STRONG STORMS MAY FORM LATE THIS AFTERNOON INTO THIS EVENING
   IN UNCAPPED...WEAKLY CONFLUENT ENVIRONMENT OVER THE SRN APLCNS. 
   30-40 KT DEEP NWLY SHEAR WILL BE FAVORABLE FOR SUSTAINED
   ACTIVITY...BUT SPARSE MOISTURE WILL LIMIT DEGREE OF INSTABILITY AND
   SHOULD MITIGATE ANY SEVERE THREAT.  WELL-MIXED SUB CLOUD LAYERS MAY
   YIELD A FEW STRONG DOWNDRAFTS WITH SOME STORMS.
   
   ..CORFIDI/JEWELL.. 05/22/2005
   
   ...NOTICE...
   THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE
   SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1...
   WUUS02 PTSDY2...WUUS03 PTSDY3.  THE INCLUSION OF POINTS
   IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005
   CONVECTIVE SEASON.  A PUBLIC NOTIFICATION STATEMENT (PNS)
   WILL PROVIDE DETAILS ON THE TRANSITION.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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