DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 151953
SWODY1
SPC AC 151951

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0251 PM CDT SAT JUN 15 2013

VALID 152000Z - 161200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL
PLAINS...LOWER MO VALLEY AND MID TO UPPER MS VALLEY...

A COUPLE CHANGES HAVE BEEN MADE TO THE OUTLOOK FOR THIS ISSUANCE.
THE FIRST IS TO SHIFT THE 30 PERCENT/SIG HAIL PROBABILITIES AND 5
PERCENT TORNADO PROBABILITY NWD A FEW COUNTIES TO BEGIN NEAR THE
WY-CO-NEB STATELINE INTERSECTION. SHORT-TERM MODEL FORECASTS SUGGEST
ONE OR TWO SEVERE STORMS WILL INITIATE IN THE LARAMIE RANGE AND MOVE
SEWD ACROSS NERN CO LATE THIS AFTERNOON AND EARLY THIS EVENING. VERY
LARGE HAIL AND A FEW TORNADOES WILL BE POSSIBLE WITH THE STRONGER
UPDRAFTS. THE SECOND CHANGE TO THE OUTLOOK IS TO REMOVE THUNDER FROM
PARTS OF SRN ND AND NCNTRL SD. ALTHOUGH THUNDERSTORMS MAY DEVELOP
LATE TONIGHT IN THE NRN HIGH PLAINS...THE ACTIVITY IS NOT EXPECTED
TO MOVE THAT FAR EAST.

..BROYLES.. 06/15/2013

.PREV DISCUSSION... /ISSUED 1129 AM CDT SAT JUN 15 2013/

...CO FRONT RANGE THIS AFTERNOON TO WRN KS BY EARLY TONIGHT...
A MOIST UPSLOPE FLOW REGIME IS BECOMING ESTABLISHED ACROSS E/NE CO
IN THE WAKE OF A MORNING COLD FRONTAL PASSAGE. STRONG SURFACE
HEATING WILL OCCUR WITHIN THE POST-FRONTAL AIR MASS...AND MIDLEVEL
LAPSE RATES WILL REMAIN STEEP...WHICH WILL SUPPORT MODERATE
INSTABILITY BY LATER THIS AFTERNOON NEAR AND E OF THE FRONT RANGE.
THOUGH LARGE SCALE FORCING FOR ASCENT WILL BE LACKING IN CONJUNCTION
WITH WEAK SHORTWAVE RIDGING ALOFT...UPSLOPE FLOW AND SURFACE HEATING
ALONG THE FRONT RANGE WILL PROMOTE ISOLATED TO WIDELY SCATTERED
THUNDERSTORM DEVELOPMENT BY MID AFTERNOON AS CONVECTIVE INHIBITION
WEAKENS. GIVEN MLCAPE OF 1500-2000 J/KG AND EFFECTIVE BULK SHEAR
AOA 40 KT WITH STRAIGHT HODOGRAPHS...A FEW SUPERCELLS WITH LARGE
HAIL CAN BE EXPECTED THIS AFTERNOON...AND POTENTIALLY A TORNADO OR
TWO. LATER THIS EVENING INTO TONIGHT...THERE WILL SOME POTENTIAL
FOR UPSCALE GROWTH INTO A CLUSTER OR TWO THROUGH OUTFLOW
INTERACTIONS...WITH STORMS AND AN ATTENDANT RISK FOR LARGE
HAIL/DAMAGING WINDS EXPECTED TO SPREAD INTO W CENTRAL/NW KS.

...SRN/CENTRAL PLAINS TO MID MS VALLEY TODAY...
MESSY SCENARIO TODAY WITH A TROPICAL MOISTURE PLUME SPREADING
NWD/NNEWD FROM TX/OK TO ERN KS/MO AND IA...IN ASSOCIATION WITH A
WEAK MIDLEVEL TROUGH AND EMBEDDED VORTICITY MAXIMA OVER NW TX AND W
CENTRAL KS AS OF MID MORNING. WIDESPREAD CONVECTION IS EXPECTED
WITHIN THIS MOISTURE PLUME TODAY...AS WELL AS ON ITS ERN FRINGE
WHERE SURFACE HEATING WILL BE STRONGER AND REMNANT STEEP MIDLEVEL
LAPSE RATES STILL RESIDE. FARTHER N...MCV/S FROM OVERNIGHT
CONVECTION ARE MOVING ESEWD NEAR CHICAGO TO THE NE OF THE UNSTABLE
SURFACE WARM SECTOR...AND NEAR A SURFACE COLD FRONT AND WITH AN
ONGOING THUNDERSTORM CLUSTER IN NW IA. THIS MCV/CLUSTER SHOULD
PERSIST THROUGH THE AFTERNOON WITH SOME SURFACE
HEATING/DESTABILIZATION IN CLOUD BREAKS IN ADVANCE OF IT...THOUGH
THE MAGNITUDE OF THE WIND/HAIL RISK IS STILL IN QUESTION.

OTHERWISE...GIVEN THE PRESENCE OF THE TROPICAL MOISTURE PLUME ...AS
WELL AS A WEAK OUTFLOW BOUNDARY IN SW MO AND THE OUTFLOW REINFORCED
WARM FRONT FROM CENTRAL IA TO W CENTRAL IL...THERE WILL BE MULTIPLE
FOCI FOR CONVECTIVE INITIATION TODAY. THOUGH A FEW SMALLER CLUSTERS
OF LARGE HAIL/DAMAGING WINDS COULD OCCUR...THE MESSY AND WIDESPREAD
NATURE OF THE CONVECTION...IN PROFILES WITH MODERATE-STRONG
INSTABILITY INITIALLY BUT MODEST VERTICAL SHEAR...SUGGEST THAT THERE
IS TOO MUCH UNCERTAINTY TO WARRANT ANY ENHANCED SEVERE
PROBABILITIES.

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