DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 071949
SWODY1
SPC AC 071946

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT THU JUN 07 2012

VALID 072000Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL HIGH
PLAINS...

THE MAIN CHANGE TO THE OUTLOOK AT 20Z IS TO MOVE THE WRN EDGE OF THE
SLIGHT RISK WWD TO ENCOMPASS TORNADO WATCH 362. THE WRN EDGE OF THE
SLIGHT NOW EXTENDS ALONG THE WRN EDGE OF ANALYZED MODERATE
INSTABILITY WHERE VISIBLE SATELLITE IMAGERY SHOWS CONVECTION
INITIATING. THE SECOND CHANGE TO THE OUTLOOK IS TO EXPAND THE 2
PERCENT TORNADO PROBABILITY SLIGHTLY WWD FOR THE SAME REASONING AS
PREVIOUSLY STATED. OTHERWISE...A FEW VERY MINOR ADJUSTMENTS HAVE
BEEN MADE TO THE OUTLOOK LINES. EVERYTHING LOOKS TO BE ON TRACK AT
THIS TIME.

..BROYLES.. 06/07/2012

.PREV DISCUSSION... /ISSUED 1126 AM CDT THU JUN 07 2012/

...NRN PLAINS INTO CENTRAL HIGH PLAINS...
WATER VAPOR IMAGERY SHOWS A PRIMARY SHORT WAVE TROUGH MOVING ENEWD
FROM CENTRAL MT SWD INTO WRN WY...WITH A SRN STREAM SHORT WAVE
TROUGH MOVING INTO THE CENTRAL ROCKIES ATTM. THESE FEATURES ARE
EXPECTED TO INFLUENCE CONVECTIVE DEVELOPMENT THIS AFTERNOON AND
EVENING...WITH SEVERAL STRONG THUNDERSTORMS ALREADY OCCURRING OVER
PARTS OF NERN WY IN ADVANCE OF THE NRN TROUGH. AT THE SURFACE...THE
PATTERN IS EXPECTED TO CHANGE LITTLE WITH A LOW OVER THE CENTRAL
DAKOTAS BORDER REGION...AND A WEAK FRONT TRAILING SSWWD ACROSS THE
NEB PANHANDLE INTO CENTRAL CO. A DENVER CYCLONE/CONVERGENCE ZONE IS
APPARENT IN THE SURFACE DATA AND THIS MAY PERSIST THROUGH MUCH OF
THE AFTERNOON. THESE FEATURES ARE EXPECTED TO FOCUS CONVECTIVE
STORMS THIS AFTERNOON AND EVENING.

VISIBLE IMAGERY INDICATES SEVERAL REGIONS OF THICKER CLOUD COVER
FROM NERN CO NNEWD INTO THE WRN DAKOTAS...AND THESE WILL MODULATE
DIABATIC HEATING AND SUBSEQUENT DESTABILIZATION DURING THE
AFTERNOON. LOW LEVEL MOISTURE WITH SURFACE DEW POINTS GENERALLY IN
THE 50S IS EXPECTED TO PERSIST ALONG/AHEAD OF THE FRONTAL
ZONE...WITH LARGER INSTABILITY /MLCAPE OF 1000-2000 J PER KG/
EXPECTED WITHIN REGIONS WHERE REDUCED CLOUD COVER AND GREATER
HEATING ARE ABLE TO OCCUR.

DYNAMIC FORCING FOR LARGE SCALE ASCENT ASSOCIATED WITH THE
AFOREMENTIONED SHORT WAVE TROUGHS IS EXPECTED TO OVERSPREAD THE WRN
EDGE OF THE LOW LEVEL MOISTURE AXIS BY EARLY-MID AFTERNOON AND
RESULT IN ADDITIONAL CONVECTIVE DEVELOPMENT. VERTICAL SHEAR IS
EXPECTED TO BE STRONGER OVER THE SRN HALF OF THE SLIGHT RISK AREA
WHERE VEERING WIND PROFILES WITH HEIGHT WILL BE MORE PRONOUNCED.
THIS WILL ENHANCE POTENTIAL FOR A FEW SUPERCELL STORMS LATER THIS
AFTERNOON AND EVENING FROM SERN WY/NEB PANHANDLE INTO NERN CO.
ALTHOUGH DIRECTIONAL SHEAR WILL BE LESS FARTHER NORTH INTO THE
DAKOTAS...DEEP LAYER SHEAR /ESPECIALLY OVER WRN AND CENTRAL ND/ MAY
BE SUFFICIENT TO SUPPORT A FEW SUPERCELL STORMS. LARGE HAIL AND
DAMAGING WINDS WILL BE THE PRIMARY SEVERE THREATS WITH STRONGER
CELLS OVER THE RISK AREA...ALTHOUGH A FEW TORNADOES MAY BE POSSIBLE
MAINLY OVER PARTS OF NERN CO INTO THE NEB PANHANDLE. SEVERE STORMS
ARE LIKELY TO PERSIST THROUGH THE EVENING HOURS AS A WEAK SOUTHERLY
LOW LEVEL JET DEVELOPS OVER PLAINS. THE SEVERE THREAT SHOULD
DIMINISH AFTER 03-6Z IN RESPONSE TO BOUNDARY LAYER COOLING AND
STABILIZATION.

...MIDDLE ATLANTIC REGION...
A WEAK SHORT WAVE TROUGH ASSOCIATED WITH COOL MID LEVEL TEMPERATURES
/-16 TO -18C AT 500MB/ IS FORECAST TO MOVE SEWD ACROSS THE AREA
TODAY. RELATIVELY CLEAR SKIES WILL PROMOTE DIURNAL HEATING THIS
AFTERNOON...AND WITH SURFACE DEW POINTS IN THE 50S...THE AIR MASS
WILL BECOME MODESTLY UNSTABLE WITH MLCAPE OF 500-750 J/KG.
RELATIVELY LOW TOPPED THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON AND EVENING AND SEVERAL MAY PRODUCE MARGINAL HAIL AND
GUSTY WINDS.

...SOUTH TEXAS...
A WEAK AND CONVECTIVELY AIDED UPPER LOW PERSISTS OVER NORTH TX.
RATHER STRONG MID LEVEL WINDS IN SOUTHWEST PERIPHERY OF THE
LOW...COUPLED WITH STRONG HEATING AND AMPLE CAPE...WILL PROMOTE THE
DEVELOPMENT OF SCATTERED STRONG STORMS THIS AFTERNOON. THIS IS MOST
LIKELY TO OCCUR ALONG AND SOUTH OF A COMPOSITE BOUNDARY EVIDENT IN
VISIBLE IMAGERY ALONG A RKP-HDO-ECY LINE. THE WRN PART OF THIS
BOUNDARY IS MOVING SWD IN RESPONSE TO REINFORCING OUTFLOW FROM
STORMS OVER CENTRAL TX.

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