Aug- 2-2004 1300 UTC Day 1 Convective Outlook
Updated: Mon Aug 2 12:57:49 UTC 2004
Categorical Graphic
20040802 1300 UTC Day 1 Outlook Graphic
Probablistic Tornado Graphic
20040802 1300 UTC Day 1 Tornado Probabilities Graphic
Probablistic Damaging Wind Graphic
20040802 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probablistic Large Hail Graphic
20040802 1300 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 021252
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0752 AM CDT MON AUG 02 2004
   
   VALID 021300Z - 031200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 75 NNE
   OLF BIS ABR 35 NW STC 65 S DLH AUW MBS 20 SSE JXN 35 SSE SBN MTO ALN
   JEF FLV GRI 25 SE MHN 35 ENE AIA GCC 20 NE LVM BTM 27U SUN 25 N OWY
   95 SSE BNO 55 ESE RDM 40 SE DLS 40 S EPH 70 ENE 63S.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 65 ESE YUM 35 SSE EED
   50 SSW DRA 55 W TPH 65 NE SVE 50 NNW SVE RBL 55 SSE EKA 15 NNE ACV
   EUG 45 NE PDX EPH 40 NNE 63S ...CONT... 25 N PBG BFD SDF 40 NNW DYR
   UMN MHK 35 S HSI IML LIC 40 E RTN 35 SE TCC LBB ABI GGG 20 NNE MEI
   ANB 45 SW CSV JKL MGW 25 WNW CXY 30 ESE BOS.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS INTERIOR PACIFIC NW...NRN
   ROCKIES TO SRN GREAT LAKES REGION...
   
   ...SYNOPSIS...
   UPPER AIR PATTERN ON SYNOPTIC SCALE REMAINS DOMINATED BY
   STRENGTHENING ANTICYCLONE CENTERED OVER OK...AND 90-110 KT 250 MB
   JET MAX OVER SRN CANADA IN ASSOCIATION WITH TIGHT HEIGHT GRADIENTS
   AROUND SRN RIM OF HUDSON BAY VORTEX.  WEAK BUT AMPLIFYING TROUGH
   WILL MOVE SLOWLY SEWD OVER TN VALLEY/SRN APPALACHIANS REGION. 
   MEANWHILE NRN CA LOW IS MOVING INLAND AND EVOLVING INTO OPEN-WAVE
   TROUGH THAT WILL REACH ORE/ID BORDER AREA BY END OF PERIOD.
   
   WAVY SFC FRONT IS ANALYZED FROM SRN LOWER MI WNWWD ACROSS CENTRAL
   MN...THEN SWWD THROUGH WEAK LOW INVOF SD BADLANDS...AND INTO ERN WY.
    BOTH SYNOPTIC FORCING AND MESOSCALE OUTFLOW-RELATED PROCESSES WILL
   SHIFT THIS FRONTAL ZONE SWD ACROSS REMAINDER SD/MN...AND MUCH OF
   IA/NEB...BY END OF PERIOD...WITH MAIN FRONTAL/LEE-SIDE LOW REFORMING
   OVER SWRN NEB/NWRN KS AREA.  SFC TROUGH AND SECONDARY FRONTAL
   BOUNDARY SHOULD BECOME QUASISTATIONARY FROM N-CENTRAL MT SEWD ACROSS
   WRN NEB.
   
   ...UPPER MS VALLEY REGION TO LOWER MI AND IL...
   TWO PRIMARY AREAS OF CONVECTION TO CONSIDER FOR SEVERE POTENTIAL --
   BOTH ONGOING AND WITH POSSIBLE REGENERATION FARTHER SE -- COMPEL EWD
   EXTENTION OF CATEGORICAL SEVERE RISK.
   
   1. MCS THAT HAS PRODUCED DAMAGING WIND AND MARGINAL SEVERE HAIL --
   ACROSS PORTIONS ND/MN...SHOULD CONTINUE MOVING SEWD INVOF FRONTAL
   ZONE -- PERHAPS ACROSS WI AND LM AS FAR AS PORTIONS LOWER MI.  THIS
   ACTIVITY MAY SURVIVE LONG ENOUGH TO BECOME SFC BASED ONCE BOUNDARY
   LAYER RECOUPLES.  SFC MESOANALYSIS SHOWS PRONOUNCED THERMAL/MOIST
   AXES JUST S OF FRONTAL ZONE WITH 50-100 NM WIDE CORRIDOR OF
   RELATIVELY LARGE THETAE.
   
   2. LARGER BUT MORE LOOSELY ORGANIZED AREA OF CONVECTION FROM NERN
   KS/NWRN MO ACROSS MUCH OF CENTRAL/ERN IA.  THIS APPEARS MORE
   MARGINAL/CONDITIONAL SEVERE THREAT.  STRONGEST OF THIS ACTIVITY --
   OVER IA MUST CROSS ANOTHER 100-150 NM OF RELATIVELY
   STABLE...LOW-THETAE SFC AIR BEFORE REACHING NNE-SSW ORIENTED
   CORRIDOR OF 60S/LOW 70S F SFC DEW POINTS IN CENTRAL AND NERN IL.  IN
   MEANTIME...LOSS OF LLJ SUPPORT MAY RESULT IN SIGNIFICANT WEAKENING
   BY ABOUT 15Z.
   
   ...N-CENTRAL LOW PLAINS AND LOWER MO VALLEY - AFTERNOON-EVENING...
   ANOTHER ROUND OF SEVERE TSTM DEVELOPMENT AND UPSCALE EVOLUTION INTO
   ONE OR TWO MCS'S IS EXPECTED FROM LATE AFTERNOON THROUGH TONIGHT --
   THIS TIME DISPLACED SLIGHTLY FARTHER S THAN PAST COUPLE DAYS ALONG
   WITH LOW LEVEL FRONTAL ZONE.  DAMAGING HAIL AND A FEW TORNADOES MAY
   OCCUR FROM ANY LATE AFTERNOON/EARLY EVENING SUPERCELLS...THOUGH
   STRONG CAPPING SHOULD INITIALLY LIMIT COVERAGE OF DIURNAL TSTMS. 
   INFLOW LAYER AIR MASS WILL REMAIN FAVORABLY MOIST ACROSS CENTRAL/NRN
   NEB...AND SHOULD RECOVER OVER NERN NEB AND WRN IA FROM EFFECTS OF
   PRIOR CONVECTIVE OVERTURNING WHICH HAS TEMPORARILY LOWERED DEW
   POINTS.  AIR MASS BETWEEN FRONT AND RESIDUAL OUTFLOW BOUNDARY SHOULD
   ACQUIRE 60S TO LOW 70S SFC DEW POINTS THROUGH MOIST ADVECTION AND
   EVAPOTRANSPIRATION...WHILE MAINTAINING SOME BACKED FLOW AND ENHANCED
   LOW LEVEL VORTICITY.  BY LATE AFTERNOON EXPECT 3000-5000 J/KG MLCAPE
   IN THAT AREA.  RESULTING MCS SHOULD TRACK SEWD ACROSS MO VALLEY
   TOWARD SRN IA/NRN MO OVERNIGHT...WITH WIND DAMAGE MAIN THREAT.
   
   ...NRN HIGH PLAINS/NRN ROCKIES...
   LARGE AREA OF POST-FRONTAL ELY FLOW WILL DEVELOP ACROSS PLAINS OF MT
   AND NERN WY.  ALTHOUGH MID-UPPER LEVEL RIDGE WILL OVERLIE WY/MT
   ROCKIES THROUGH MUCH OF PERIOD...AIR MASS SHOULD MOISTEN AND
   DESTABILIZE SUFFICIENTLY TO SUPPORT TSTM DEVELOPMENT THIS AFTERNOON
   -- PARTICULARLY OVER HIGHER TERRAIN AND INVOF SFC TROUGH.  STRONG
   LOW-MIDLEVEL DIRECTIONAL SHEAR SHOULD CONTRIBUTE TO FAVORABLE 0-3 KM
   HODOGRAPHS -- I.E.. 150-250 J/KG SRH -- AND MARGINAL DEEP LAYER
   SHEARS -- 35-40 KT -- FOR SUPERCELLS WITH ACCOMPANYING LARGE HAIL
   THREAT...PERHAPS EVOLVING INTO BOWS.  WIND DAMAGE POTENTIAL ALSO
   WILL EXIST GIVEN RATHER DEEPLY MIXED BOUNDARY LAYERS INTO WHICH ANY
   CONVECTION WILL BE MOVING.
   
   ...ERN ORE/ID THROUGH GREAT BASIN REGION...
   WIDELY SCATTERED TSTMS SHOULD DEVELOP FROM ERN ORE/SERN WA ACROSS
   PORTIONS ID THIS AFTERNOON...AS CAP WEAKENS AND MIDLEVEL LAPSE RATES
   STEEPEN AHEAD OF APCHG MIDLEVEL TROUGH.  BROAD AREA OF SFC LOW
   PRESSURE PRESENTLY ANALYZED OVER ERN WA/ORE SHOULD GENERALLY REMAIN
   IN PLACE THROUGH AFTERNOON...AND WILL BE MOST FAVORED AREA FOR
   DEVELOPMENT.  SFC HEATING AND MOISTURE SHOULD BE STRONG ENOUGH TO
   SUPPORT 500-1000 J/KG MLCAPE WITH MIXED BOUNDARY LAYERS EXTENDING UP
   TO WITHIN 575-650 MB LAYER.  SOME ACTIVITY MAY ORGANIZE INTO SHORT
   LINE SEGMENTS OR BOWS WITH ENHANCED DAMAGING WIND POTENTIAL.  LARGE
   HAIL ALSO IS POSSIBLE.
   
   SEVERE PROBABILITIES WILL BECOME MORE SPORADIC WITH SWD/SEWD EXTENT
   FROM ERN ORE THROUGH NV AND UT AS LARGE SCALE SUPPORT DIMINISHES
   AWAY FROM PACIFIC COAST TROUGH.  HOWEVER...DEEPLY MIXED BOUNDARY
   LAYERS AND STEEP MIDLEVEL LAPSE RATES WILL OFFSET DRY SFC AIR ENOUGH
   TO YIELD 300-600 J/KG MLCAPE OVER BASINS.  A FEW DRY MICROBURSTS
   WITH GUSTS NEAR SEVERE LEVELS ARE POSSIBLE.
   
   ...COASTAL CAROLINAS -- TS ALEX...
   GIVEN FCST WIND FIELDS OVER NRN SEMICIRCLE OF THIS SYSTEM...LOW
   LEVEL VERTICAL SHEAR WILL BE WEAK TO MARGINAL FOR SUSTAINED LOW-TOP
   SUPERCELLS...YIELDING ONLY OUTSIDE POTENTIAL FOR BRIEF/WEAK
   TORNADOES.  HOWEVER...ANY STRENGTHENING/EXPANSION OF THIS SYSTEM
   BEYOND CURRENT PROGS...AND/OR ANY DEEPER INLAND SPREAD OF FAVORABLE
   SHEAR OVER NERN QUADRANT...MIGHT ENLARGE HODOGRAPH AND ELEVATE
   TORNADO PROBABILITIES PAST CATEGORICAL OUTLOOK CRITERIA.  REF NHC
   ADVISORIES UNDER WMO HEADER WTNT21 KNHC FOR LATEST TS
   WATCHES/WARNINGS...AND FCSTS OF TRACK AND SFC WIND FIELDS.
   
   ..EDWARDS/GUYER.. 08/02/2004
   
   ...NOTICE...
   FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
   LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
   GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
   HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
   INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 1630Z