Aug 5, 2011 0600 UTC Day 1 Convective Outlook
Updated: Fri Aug 5 05:52:08 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110805 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110805 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
20110805 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
20110805 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.
   SPC AC 050548
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1248 AM CDT FRI AUG 05 2011
   
   VALID 051200Z - 061200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS NRN PLAINS...
   
   ...SYNOPSIS...
   INTENSE MID-UPPER ANTICYCLONE OVER ARKLATEX REGION WILL REMAIN
   DOMINANT FEATURE OVER SRN HALF OF CONUS...AS ITS CENTER DRIFTS WWD
   ACROSS N TX.  MEANWHILE...QUASI-ZONAL BELT OF NRN STREAM FLOW WILL
   PERSIST FROM PAC NW TO UPPER GREAT LAKES...WITH SEVERAL EMBEDDED
   SHORTWAVES.  MOST OF THESE WILL BE LOW-AMPLITUDE IN NATURE...EXCEPT
   FOR TROUGHING NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER INTERIOR
   NWRN CONUS.  LEADING ASSOCIATED VORTICITY MAX OVER ID SHOULD BECOME
   PRIMARY 500-MB PERTURBATION DAY-1...MOVING EWD ACROSS MT AND
   REACHING ND BY END OF PERIOD.  MEANWHILE...CONVECTIVELY
   INDUCED/AMPLIFIED VORTICITY MAX OVER MID MS VALLEY REGION SHOULD
   DEAMPLIFY GRADUALLY AS IT MOVES EWD TOWARD OH BY 5/00Z...WHILE MCV
   OVER SERN AL/SWRN GA AREA DRIFTS SWWD ACROSS CENTRAL GULF COAST. 
   ANOTHER MCV...EVOLVING FROM CONVECTION ACROSS WRN KS...IS EXPECTED
   TO MOVE EWD GENERALLY TOWARD MKC AREA AND NRN MO THROUGH PERIOD. 
   
   AT SFC...FRONTAL ZONE NOW QUASISTATIONARY OVER ND IS EXPECTED TO
   REMAIN SO THROUGH 6/00Z...WITH SOME EFFECTIVE MODULATION POSSIBLE IN
   RESPONSE TO INTERVENING CONVECTION.  AS MID-UPPER TROUGH MOVES OVER
   NRN HIGH PLAINS DURING  LATTER HALF OF PERIOD...DEEPENING LEE
   CYCLONE OVER MT WILL MOVE EWD AS FRONTAL-WAVE LOW...REACHING WRN/SRN
   ND BY 6/12Z.  FARTHER SE...BROAD/RESIDUAL BAROCLINIC ZONE WILL
   PERSIST THROUGH 6/00Z FROM SRN PIEDMONT/CAROLINAS SWWD OVER PORTIONS
   GA/AL...THEN WNWWD TO NRN OK/SRN KS.  BY THAT TIME...FRONT SHOULD BE
   CLOSE TO...OR LINKED WITH...PROBABLE HEAT LOW OVER OK...WITH VERY
   HOT AND LOW-RH BOUNDARY LAYER TO ITS S OVER SRN PLAINS.
   
   ...NRN PLAINS...
   SCATTERED TSTMS SHOULD DEVELOP OVER PORTIONS CENTRAL/ERN MT DURING
   AFTERNOON AND MOVE EWD...WITH MIXTURE OF SUPERCELL AND MULTICELL
   MODES INITIALLY POSSIBLE.  ACTIVITY SHOULD GROW UPSCALE TO MCS WITH
   PRIMARY THREAT EVOLVING TO DAMAGING WIND IN CORRIDOR FROM ERN MT NOT
   PORTIONS ND THROUGH EVENING AND EARLY OVERNIGHT HOURS.  SVR
   POTENTIAL THEN SHOULD DIMINISH LATE NIGHT AS CONVECTION ENCOUNTERS
   PROGRESSIVELY WEAKER BOUNDARY-LAYER INSTABILITY...BOTH WITH TIME AND
   WITH EWD EXTENT.
   
   AFTERNOON INITIATION IS FCST IN REGIME OF FAVORABLY STEEP
   MIDDLE-LEVEL LAPSE RATES AIDED BY DCVA ALOFT...INCREASING MOISTURE
   WITH EWD EXTENT...FRONTAL/CYCLONIC CONVERGENCE NEAR SFC
   LOW...DIABATIC SFC HEATING TO STEEPEN SUBCLOUD LAPSE RATES AND
   CONTRIBUTE TO CINH REMOVAL...FAVORABLE STORM-RELATIVE INFLOW...AND
   ENHANCED LOW-LEVEL VORTICITY INVOF FRONT.  GIVEN THIS ANTICIPATED
   JUXTAPOSITION OF FAVORABLE FOCI AND PARAMETERS...STG CONSENSUS
   EXISTS AMONG OPERATIONAL MODELS AND SREF MEMBERS WITH CONCENTRATED
   AREA OF CONVECTIVE PRECIP MOVING EWD FROM MT TO SD FROM AFTERNOON
   THROUGH EVENING.  AGGREGATE OUTFLOW MAY RESULT IN
   FORWARD-PROPAGATING MCS ALIGNED NEARLY ORTHOGONAL TO DEEP-LAYER WIND
   VECTOR IN SUPPORT OF WIND POTENTIAL.
   
   MORE WIDELY SCATTERED TSTMS ARE POSSIBLE FARTHER S ACROSS ERN WY AND
   WRN SD...WITH SOME OROGRAPHIC LIFT AIDING IN INITIATION.  DEEP-LAYER
   SHEAR WILL WEAKEN WITH SWD EXTENT...PROGRESSIVELY LIMITING POTENTIAL
   ORGANIZATION/LONGEVITY OF CONVECTION.  ISOLATED TO WIDELY SCATTERED
   TSTMS ALSO MAY DEVELOP DIURNALLY ALONG FRONTAL SEGMENT ACROSS ERN ND
   AND NRN MN...WITH ISOLATED SVR HAIL/GUSTS POSSIBLE.  WEAK LOW-LEVEL
   FLOW WILL LIMIT HODOGRAPH SIZE AND DEEP-LAYER SHEAR..ALTHOUGH AREA
   WILL RESIDE ON SRN FRINGE OF STRONGER 200-300 MB LAYER FLOW.
   
   ...CENTRAL PLAINS TO SERN CONUS...
   WIDELY SCATTERED TO SCATTERED TSTMS ARE POSSIBLE AGAIN THIS
   AFTERNOON...WITH ASSORTED FOCI INCLUDING SEA BREEZES/OUTFLOWS NEAR
   ATLC AND GULF COASTS...OUTFLOW/DIFFERENTIAL HEATING BOUNDARIES NEAR
   RESIDUAL CLOUD COVER OVER PORTIONS MS/AL OR MID-SOUTH REGIONS...AND
   ALONG AND N OF FRONTAL ZONE AND RESIDUAL OUTFLOWS FROM
   PRIOR/OVERNIGHT CONVECTION FROM OZARKS INTO CENTRAL PLAINS. 
   RELATIVE NODES OR MAXIMA ARE PROBABLE WITHIN THIS BROAD
   SWATH...WHICH WILL BE UNDER GENERALLY WEAK DEEP-TROPOSPHERIC FLOW
   AND SHEAR IN SUPPORT OF MULTICELLULAR AND PULSE MODES.  SUCH NODES
   ARE SO DEPENDENT ON MESOSCALE FOCI -- SOME YET TO DEVELOP -- THAT
   THERE IS TOO MUCH UNCERTAINTY ATTM FOR UNCONDITIONAL/15% THRESHOLD
   CATEGORICAL RISK AREA.  ONE AREA OF CONCERN IN PARTICULAR MAY BE
   FROM SRN KS ACROSS SRN MO...WHERE FRONTAL AND DIABATIC ASCENT MAY
   COMBINE WITH ENHANCED GRADIENT FLOW S OF MCV.  SHAPE/DENSITY
   EWD-MOVING CLOUD DEBRIS FROM ONGOING CONVECTIVE REGIME OVER WRN KS
   MAY EXERT CONSIDERABLE INFLUENCE ON MORE PRECISE AREAS FOR
   CONVECTIVE/SVR POTENTIAL.
   
   ..EDWARDS/GRAMS.. 08/05/2011
   
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