Jun 29, 2011 2000 UTC Day 1 Convective Outlook
Updated: Wed Jun 29 20:03:04 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110629 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110629 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
20110629 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
20110629 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.
   SPC AC 291958
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0258 PM CDT WED JUN 29 2011
   
   VALID 292000Z - 301200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN INTERMOUNTAIN
   REGION AND NRN ROCKIES...
   
   ...NRN INTERMOUNTAIN REGION/NRN ROCKIES...
   STORMS HAVE BEEN GRADUALLY DEVELOPING FROM CENTRAL ID INTO SWRN
   MT...DOWNSTREAM FROM THE CENTRAL CA UPPER LOW WITHIN LEFT EXIT
   REGION OF UPPER LEVEL JET STREAK OVER NV INTO SRN ID.  STORMS ARE
   EXPECTED TO GRADUALLY INCREASE IN INTENSITY THIS AFTERNOON AND
   EVENING AS THEY MOVE NEWD WITHIN ENVIRONMENT OF SUFFICIENT
   INSTABILITY/STEEP LAPSE RATES...DRY SUBCLOUD LAYER AND STRONG DEEP
   LAYER SHEAR.  STRONGER CELLS WILL BE CAPABLE OF PRODUCING DAMAGING
   WINDS AND HAIL.  SEE MESOSCALE DISCUSSION 1441 FOR MORE DETAILED
   INFORMATION.
   
   ...CENTRAL/NRN NV INTO SWRN ID...
   A FEW STRONG STORMS HAVE DEVELOPED IMMEDIATELY EAST/NORTHEAST OF THE
   UPPER LOW OVER CENTRAL CA...AND THIS ACTIVITY WILL CONTINUE THROUGH
   THE EVENING HOURS AS PRONOUNCED DYNAMIC FORCING FOR ASCENT
   OVERSPREADS THE REGION.  THERE WILL BE A RISK FOR MARGINALLY SEVERE
   HAIL AND STRONG WINDS WITH MORE INTENSE CELLS...BUT OVERALL LIMITED
   COVERAGE WILL PRECLUDE HIGHER SEVERE PROBABILITIES.
   
   ...CENTRAL/ERN UT INTO WRN WY...
   NNE-SSW BANDS OF CONVECTION HAVE BEEN FORMING OVER UT INTO SWRN
   WY...WHERE THE ENVIRONMENT IS CHARACTERIZED BY A DEEP BOUNDARY LAYER
   WITH CONSIDERABLE DRY AIR IN THE SUB-CLOUD LAYER. THIS WILL ENHANCE
   POTENTIAL DOWNDRAFT STRENGTH...AND STEEP LAPSE RATES WILL PROMOTE
   DOWNWARD TRANSFER OF MOMENTUM WITH A RISK OF ISOLATED STRONG
   MICROBURST WINDS.
   
   ..WEISS.. 06/29/2011
   
   .PREV DISCUSSION... /ISSUED 1126 AM CDT WED JUN 29 2011/
   
   ...MT/ID THIS AFTERNOON INTO TONIGHT...
   
   VORTICITY MAXIMUM CURRENTLY PIVOTING AROUND ERN PERIPHERY OF UPPER
   LOW WILL EJECT NEWD ACROSS REGION TODAY INTO INCREASINGLY CONFLUENT
   FLOW REGIME OVER THE NRN INTERMOUNTAIN REGION.  FORCING FOR ASCENT
   ASSOCIATED WITH THIS FEATURE COUPLED WITH FRONTAL CONVERGENCE AND
   OROGRAPHIC INFLUENCES ARE EXPECTED TO FOSTER AN INCREASE IN TSTMS
   THIS AFTERNOON INTO TONIGHT.  12Z BOI SOUNDING AND GPS PW DATA
   INDICATE A PLUME OF HIGHER MOISTURE CONTENT ALONG AND AHEAD OF
   PACIFIC FRONT.  WHEN COUPLED WITH A STEEP LAPSE RATE
   ENVIRONMENT...EXPECT AFTERNOON MLCAPE TO APPROACH 1000-1500 J/KG. 
   THIS INSTABILITY AXIS WILL COINCIDE WITH A BELT OF 45-55 KT SWLY
   WINDS AT 500 MB...RESULTING IN SUFFICIENT DEEP-LAYER SHEAR FOR
   ORGANIZED STORM MODES INCLUDING SUPERCELLS AND BOWING STRUCTURES. 
   LARGE HAIL AND DAMAGING WIND GUSTS WILL BE THE PRIMARY HAZARDS OWING
   TO THE STEEP LAPSE RATES AND POTENTIAL FOR STRONG EVAPORATIVE
   COOLING IN THE SUB-CLOUD LAYER.
   
   ...ERN UT/WRN CO/WRN WY THIS AFTERNOON/EVENING...
   
   ENVIRONMENT IS EXPECTED TO REMAIN DRIER THAN POINTS TO THE NORTH AND
   WEST TODAY...THOUGH THE PRESENCE OF STEEP LAPSE RATES WILL BE
   SUPPORTIVE OF MLCAPE OF 250-500 J/KG AHEAD OF THE FRONT THIS
   AFTERNOON AND EVENING.  THE LEADING EDGE OF WEAK HEIGHT FALLS
   ATTENDANT TO THE MID AND UPPER-LEVEL TROUGH COMBINED WITH
   PRE-FRONTAL CONFLUENT FLOW IN THE LOW LEVELS WILL CONTRIBUTE TO
   WIDELY SCATTERED TSTMS THIS AFTERNOON INTO TONIGHT.  LOCALLY
   DAMAGING WIND GUSTS WILL ACCOMPANY THESE STORMS DUE TO THE
   DEVELOPMENT OF A DEEPLY MIXED BOUNDARY LAYER WITH LARGE T-TD
   SPREADS.
   
   ...MN/WI LATE TONIGHT...
   
   EWD PROGRESSION OF HEIGHT FALLS INTO THE HIGH PLAINS DURING THE
   LATTER HALF OF D1 WILL SERVE TO ENHANCE NOCTURNAL LLJ
   STRENGTH/BREADTH FROM THE SRN HIGH PLAINS INTO THE UPPER MS VALLEY. 
   THIS PROCESS WILL OCCUR BENEATH EWD-EXPANDING EML...RESULTING IN THE
   DEVELOPMENT OF MODERATE-STRONG ELEVATED INSTABILITY. 
   HOWEVER...GIVEN THE ANTICIPATED STRENGTHENING OF THE
   CAP...UNCERTAINTY EXISTS WITH REGARD TO EXACTLY WHERE ANY MORE
   ROBUST HAIL POTENTIAL WILL DEVELOP LATE TONIGHT INTO THU MORNING.
   
   ...SERN ATLANTIC AND GULF COASTS THIS AFTERNOON/EVENING...
   
   12Z REGIONAL SOUNDINGS INDICATE THE PRESENCE OF A VERY MOIST AIR
   MASS WITH PW VALUES OF AROUND 2 INCHES.  HOWEVER...CONSIDERABLE TSTM
   DEVELOPMENT ON TUE HAS RESULTED A NOTABLE WEAKENING TO THE MIDLEVEL
   LAPSE RATES.  DEVELOPING SEA BREEZE CIRCULATIONS COMBINED WITH THE
   PRESENCE OF THE SYNOPTIC FRONT AND PRE-FRONTAL TROUGH ARE EXPECTED
   TO FOCUS SCATTERED-WIDESPREAD TSTMS ONCE AGAIN TODAY. 
   HOWEVER...GIVEN THE POOR MIDLEVEL LAPSE RATES AND THE CONTINUED WEAK
   VERTICAL SHEAR...TSTMS ARE EXPECTED TO REMAIN RATHER DISORGANIZED
   WITH LOCALLY DAMAGING WIND GUSTS POSSIBLE.
   
   ...ARKLATEX/RED RIVER VALLEY THIS AFTERNOON/EVENING...
   
   RESIDUAL OUTFLOW BOUNDARIES REMNANT FROM DECAYED NOCTURNAL TSTM
   ACTIVITY MAY ONCE AGAIN SERVE AS THE FOCI FOR ISOLATED TSTM
   DEVELOPMENT THIS AFTERNOON AND EVENING.  12Z FWD SOUNDING SUGGESTS
   THAT AS TEMPERATURES WARM INTO THE MID/UPPER 90S THE CAP WILL BECOME
   INCREASINGLY WEAK WITH MLCAPE APPROACHING 3000 J/KG.  WHILE VERTICAL
   SHEAR WILL REMAIN RATHER WEAK...THE THERMODYNAMIC ENVIRONMENT WILL
   BE SUPPORTIVE OF SOME HAIL AND LOCALLY DAMAGING WIND GUSTS SHOULD
   STORMS DEVELOP.
   
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