DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 202000
SWODY1
SPC AC 201958

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT WED JUN 20 2012

VALID 202000Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM WRN UPPER MI TO IA...

...THERE IS A SLGT RISK OF SVR TSTMS FROM S-CNTRL KS TO THE NRN TX
PANHANDLE...

...MN/WI/IA/UPPER MI...
MINIMAL CHANGE TO SEVERE PROBABILITIES WITH PREVIOUS FORECAST ON
TRACK. CONVECTION WILL CONTINUE TO INCREASE WITHIN A COLD FRONTAL
ZONE EXTENDING FROM E-CNTRL MN TO SERN NEB. A PRE-FRONTAL WIND SHIFT
AND EXTENSIVE STRATOCU DECK IS LIMITING STRONGER HEATING/STEEPER
LOW-LEVEL LAPSE RATES. STILL...MODERATE BUOYANCY AND STRONG
DEEP-LAYER SWLYS PARALLELING THE BOUNDARY SHOULD BE SUFFICIENT FOR A
COUPLE OF BOW/LEWP STRUCTURES CAPABLE OF ISOLATED DAMAGING
WIND/SEVERE HAIL.

...KS/OK/TX...
MINOR TWEAKS TO SEVERE PROBABILITIES BASED ON CURRENT FRONTAL
POSITION IN N-CNTRL KS TO THE NWRN TX PANHANDLE. ALTHOUGH ISOLATED
TO SCATTERED TSTMS WILL DEVELOP ALONG THE FRONT...WINDS ARE
CURRENTLY DECREASING WITH HEIGHT PER AREA PROFILER/VWP DATA.
HIGHER-LEVEL NWLYS SHOULD STRENGTHEN SOMEWHAT ON THE GLANCING
INFLUENCE OF THE SPEED MAX EJECTING ACROSS NERN CO INTO NEB. THIS
SHOULD RENDER MARGINALLY ORGANIZED UPDRAFTS WITH A RISK FOR ISOLATED
DAMAGING WINDS/SEVERE HAIL.

...NY/VT...
NO CHANGES MADE TO PREVIOUS FORECAST.

..GRAMS.. 06/20/2012

.PREV DISCUSSION... /ISSUED 1127 AM CDT WED JUN 20 2012/

...MN/WI/IA...
AN EXPANSIVE UPPER RIDGE IS PRESENT TODAY OVER MOST OF THE EASTERN
AND SOUTHERN STATES...WHILE AN UPPER TROUGH DOMINATES THE WEATHER
OVER THE NORTHERN PLAINS. THE PRIMARY SURFACE BOUNDARY ASSOCIATED
WITH THE TROUGH EXTENDS FROM NORTHWEST WI INTO CENTRAL NEB...THEN
SOUTHWESTWARD INTO THE OK/TX PANHANDLES. THIS BOUNDARY WILL BE THE
FOCUS FOR SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING.

A FAST-MOVING CLUSTER OF STORMS NEAR DLH WILL MOVE INTO LAKE
SUPERIOR SOON. HOWEVER...CONVERGENCE ALONG THE TRAILING SURFACE
BOUNDARY WILL LIKELY RESULT IN SCATTERED THUNDERSTORM DEVELOPMENT
OVER PARTS OF WESTERN WI...SOUTHEAST MN...AND EASTERN IA BY MID/LATE
AFTERNOON. THE AIR MASS AHEAD OF THE BOUNDARY IS QUITE MOIST AND
WILL BECOME MODERATELY UNSTABLE WITH MLCAPE VALUES OVER 2000 J/KG.
STEERING FLOW PARALLEL WITH THE BOUNDARY WILL LIKELY RESULT IN A
LONG SQUALL LINE THIS EVENING ALONG THE BOUNDARY AS IT MOVES ACROSS
THE SLIGHT RISK AREA. LAPSE RATES ARE NOT PARTICULARLY STEEP...BUT
THE POTENTIAL EXISTS FOR A FEW BOW/LEWP STRUCTURES ALONG THE LINE
RESULTING IN CORRIDORS OF DAMAGING WINDS AND HAIL.

...KS/OK/TX...
MORNING SURFACE ANALYSES SHOW A COLD FRONT SURGING SOUTHWARD ALONG
THE CENTRAL HIGH PLAINS. THIS BOUNDARY WILL LIKELY EXTEND FROM
NORTHEAST NM INTO SOUTH-CENTRAL KS BY LATE AFTERNOON. FULL HEATING
WILL RESULT IN DEEP MIXING AND HELP WEAKEN THE CAP...RESULTING IN
SCATTERED THUNDERSTORM DEVELOPMENT ALONG THE FRONT. 30+ DEGREE
SURFACE T-TD SPREADS...STEEP LOW LEVEL LAPSE RATES...MLCAPE VALUES
OVER 2000 J/KG...AND STRENGTHENING NORTHWESTERLY MID LEVEL WINDS
WILL COMBINE TO YIELD A RISK OF ISOLATED SEVERE STORMS. LOCALLY
DAMAGING WINDS WILL BE THE MAIN THREAT...ALTHOUGH HAIL IS ALSO
POSSIBLE IN THE STRONGEST STORMS.

...NY/VT...
MODELS DIFFER ON EXTENT OF CONVECTION THAT WILL AFFECT NY/NEW
ENGLAND THIS AFTERNOON AND EVENING. THE AREA MOST LIKELY TO SEE A
FEW THUNDERSTORMS WILL BE ACROSS NORTHEAST NY AND NORTHERN VT. IF
STORMS CAN FORM IN THIS AREA...RATHER STRONG NORTHWESTERLY MID/UPPER
LEVEL FLOW COMBINED WITH MODERATE INSTABILITY WILL POSE A RISK OF A
FEW STRONG/SEVERE STORMS CAPABLE OF GUSTY WINDS AND HAIL.

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