SPC AC 071629
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT SUN JUN 07 2009
VALID 071630Z - 081200Z
...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
TONIGHT FOR NE KS...SE NE...NW MO...SW IA...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK...FROM
NE CO EWD TO NRN IL...
...CENTRAL PLAINS AREA THROUGH TONIGHT...
A SRN STREAM MID LEVEL TROUGH IS EJECTING NEWD FROM CENTRAL NM/CO
TOWARD KS/NEB...AROUND THE SERN PERIPHERY OF A LARGE MID LEVEL LOW
FORMING OVER SRN SK. FARTHER S...A MORE SUBTLE WAVE ALSO MOVES NEWD
FROM W TX TOWARD OK. AT THE SURFACE...A BAROCLINIC ZONE EXTENDS
FROM NE CO ACROSS WRN KS TO A REMNANT LEE CYCLONE IN CENTRAL
KS...THEN NEWD ACROSS SE NEB AND SRN IA. A SEPARATE OUTFLOW
BOUNDARY FROM OVERNIGHT CONVECTION IS LOCATED FARTHER S FROM NE KS
ACROSS CENTRAL MO /S OF I-70/. S OF THE SURFACE LOW...A DRYLINE
WILL MIX EWD THIS AFTERNOON INTO S CENTRAL KS...WRN OK...AND NW TX.
THE SURFACE BAROCLINIC ZONE...AS WELL AS THE DRYLINE NEAR THE TRIPLE
POINT AND PERHAPS THE REMNANT OUTFLOW BOUNDARY...WILL ACT TO FOCUS
THUNDERSTORM DEVELOPMENT THIS AFTERNOON INTO TONIGHT.
THE PRIMARY CONCERN ACROSS THE OUTLOOK AREA WILL BE THE STRENGTH OF
THE CAP AND THUNDERSTORM COVERAGE THIS AFTERNOON/EVENING. REGIONAL
12Z SOUNDINGS SHOW THAT A VERY WARM EML HAS OVERSPREAD THE KS/OK
WARM SECTOR...AND LOW-LEVEL MOISTURE IS STILL MARGINAL ACROSS TX/OK.
WITH SURFACE TEMPERATURES OF 95-100 F NEEDED TO MINIMIZE CONVECTIVE
INHIBITION ACROSS KS/OK...IT APPEARS THAT FOCUSED LOW-LEVEL ASCENT
FROM THE TRIPLE POINT NEWD WILL BE NEEDED TO INITIATE THUNDERSTORMS
THIS AFTERNOON...AS THE MID LEVEL WAVE APPROACHES FROM THE W.
FARTHER S...STORM COVERAGE ALONG THE DRYLINE SHOULD BE MORE ISOLATED
THAN PREVIOUS DAYS GIVEN THE DRYLINE LOCATION AT A LOWER ELEVATION
AND THE WARMER EML. THE 12Z NAM DEVELOP CONVECTIVE PRECIPITATION
ACROSS NRN OK THIS AFTERNOON...THOUGH THIS MAY BE AN ARTIFACT OF MID
LEVEL MOISTENING /WITH THE N-S CLOUD BAND CROSSING NW TX AND WRN OK/
TRIGGERING THE BMJ SCHEME IN AN OTHERWISE CAPPED PROFILE.
THE MORE PROBABLE AREA FOR SURFACE-BASED STORM DEVELOPMENT THIS
AFTERNOON WILL BE TO THE NE OF THE STRONGER CAPPED AREAS IN
KS/OK...WHERE LOW-LEVEL MOISTURE WILL BE MAXIMIZED INVOF THE REMNANT
OUTFLOW BOUNDARY AND THE BAROCLINIC ZONE. THE COMBINATION OF
MODERATE-STRONG INSTABILITY /MLCAPE OF 2000-3000 J/KG/ AND BACKED
LOW-LEVEL FLOW WITH CLOCKWISE TURNING HODOGRAPHS WILL BE SUPPORTIVE
OF SUPERCELLS WITH A FEW TORNADOES...VERY LARGE HAIL...AND DAMAGING
WINDS. FARTHER SW INTO SRN KS/NRN OK...ANY STORM DEVELOPMENT WILL
REMAIN QUITE ISOLATED...WITH PRIMARILY A THREAT FOR LARGE HAIL.
OVERNIGHT...EXPECT CONVECTION TO INCREASE IN COVERAGE AS THE MID
LEVEL WAVE EJECTS NEWD OVER KS/NEB AND THE SURFACE LOW DEVELOPS NEWD
TOWARD IA...WITH A CONTINUING THREAT FOR LARGE HAIL AND DAMAGING
WINDS.
...NE CO THIS AFTERNOON...
CLOUD BREAKS N OF THE SURFACE COLD FRONT AND A MOIST UPSLOPE FLOW OF
LOW-MID 50S BOUNDARY LAYER DEW POINTS WILL CONTRIBUTE TO WEAKENING
CONVECTIVE INHIBITION AND THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT
BY 17-19Z. VERTICAL SHEAR WILL BE FAVORABLE FOR SUPERCELLS TO
PROPAGATE EWD ALONG THE COOL SIDE OF THE FRONT...WITH AN
ACCOMPANYING THREAT FOR LARGE HAIL AND PERHAPS AN ISOLATED TORNADO
WHERE SHEAR IS MAXIMIZED ALONG THE COOL SIDE OF THE BOUNDARY BUT THE
CONVECTION REMAINS ROOTED AT THE SURFACE. THIS CONVECTION WILL
LIKELY PERSIST AND SPREAD NEWD ABOVE THE SHALLOW COOL AIR MASS INTO
NEB...WITH LARGE HAIL THE MAIN THREAT INTO THIS EVENING.
...CENTRAL/S FL THIS AFTERNOON...
THE LINGERING COLD CORE MID LEVEL LOW OVER FLOW AND SEA BREEZE
BOUNDARIES WILL PROMOTE SCATTERED-NUMEROUS THUNDERSTORMS THROUGH THE
AFTERNOON ACROSS CENTRAL/S FL. MODERATE INSTABILITY AND SEASONALLY
COOL MID LEVEL TEMPERATURES WILL AGAIN PROMOTE A THREAT FOR AT LEAST
ISOLATED LARGE HAIL AND STRONG DOWNBURST WINDS.
..THOMPSON/GRAMS.. 06/07/2009
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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