SPC 2000Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0258 PM CDT SAT JUN 02 2012 VALID 022000Z - 031200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF S CENTRAL TO ERN MT... ...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN CO AND FAR WRN KS SWD THROUGH PORTIONS OF THE SRN HIGH PLAINS... ...MID MS VALLEY/MIDWEST... GIVEN CURRENT TRENDS PER SATELLITE/RADAR IMAGERY AND JUXTAPOSITION OF GREATER INSTABILITY /THOUGH RELATIVELY WEAK --- MUCAPE BELOW 800 J PER KG/ AND EFFECTIVE BULK SHEAR OF 25-35 KT...THE LOW SEVERE HAIL/WIND PROBABILITIES HAVE BEEN SHIFTED EWD ACROSS MORE OF CENTRAL IL AND SWRN IND. ...S CENTRAL TO ERN MT... FORECAST REMAINS ON TRACK FOR A SVR WEATHER EVENT ACROSS THIS REGION. THE ONLY CHANGE TO THE OUTLOOK FOR THIS REGION IS TO EXTEND THE SLIGHT RISK FOR AN ENHANCED THREAT OF STRONGER WIND GUSTS REACHING THE MT/ND BORDER. ALTHOUGH INSTABILITY IS EXPECTED TO WEAKEN WITH EWD EXTENT...STRONGER WINDS SPREADING EWD INTO THE NRN HIGH PLAINS AND COLD POOL ENHANCEMENT COULD EXTEND THE SEVERE THREAT FARTHER EAST THAN PREVIOUSLY FORECAST. ...CO/SRN HIGH PLAINS... FORECAST REMAINS ON TRACK FOR THE THREAT OF STRONG GUSTY WINDS AND SOME HAIL ACCOMPANYING CONVECTION MOVING OFF THE HIGHER TERRAIN/FRONT RANGE INTO THE HIGH PLAINS THIS AFTERNOON WHERE OBJECTIVE ANALYSES INDICATE ONGOING DESTABILIZATION. SHORT TERM MESOSCALE DETAILS ARE AVAILABLE IN SPC MESOSCALE DISCUSSION 1021. ..PETERS.. 06/02/2012 .PREV DISCUSSION... /ISSUED 1128 AM CDT SAT JUN 02 2012/ ...MT... SHORT WAVE TROUGH EVIDENT IN WV IMAGERY CROSSING WA ATTM WILL TRANSLATE QUICKLY EAST THROUGH THE DAY AND ACT TO DAMPEN UPPER RIDGE AXIS SITUATED ACROSS MT/WY. INCREASING LARGE SCALE ASCENT SHOULD CONTRIBUTE TO STEEPENING MID LEVEL LAPSE RATES WHERE PW VALUES ACROSS THE NRN ROCKIES ARE ALREADY AOA 150 PCT OF NORMAL. VSBL SATELLITE IMAGERY DEPICTS CLOUD-FREE CONDITIONS UNDER THE RIDGE AXIS OVER THE ERN HALF OF MT AND NRN WY AND...DESPITE INCREASING CLOUDINESS MOVING IN FROM THE WEST...LOW LEVEL WARMING WILL AID IN MODEST DESTABILIZATION COINCIDENT WITH THE ARRIVAL OF STRONGER ASCENT WITH THE SHORT WAVE AND ADVANCE/REFORMATION OF ASSOCIATED PACIFIC FRONT LATER TODAY. MLCAPE OF 500-800 J/KG AND INCREASING WSWLY FLOW ALOFT SHOULD PROVE SUFFICIENT FOR AN INCREASE IN STORM ORGANIZATION THROUGH THE LATE AFTERNOON AND INTO THE EVENING FROM ERN ID ACROSS NRN WY AND MUCH OF ERN MT. EXPECT A NUMBER OF CLUSTERS OR BANDS OF STORMS TO SPREAD EAST DURING THIS PERIOD OF THE DAY WITH A FEW OF THE STRONGER UPDRAFTS CAPABLE OF PRODUCING HAIL UP TO AN INCH IN DIAMETER ALONG WITH A SCATTERING OF POTENTIALLY DAMAGING WIND REPORTS. GREATEST CONCENTRATION OF SEVERE STORM POTENTIAL SHOULD OCCUR OVER SCNTRL/ERN MT WITH MORE ISOLD SEVERE STORMS POSSIBLE FROM ERN ID ACROSS NRN WY. WHILE A RESULTING SMALL MCS OR TWO MAY SPREAD EAST INTO THE WRN DAKOTAS TONIGHT...PARTLY SUSTAINED BY LIFT ON THE NOSE OF NOCTURNAL LLJ...SEVERE HAIL AND WIND POTENTIAL SHOULD BECOME INCREASINGLY CONSTRAINED BY LACK OF INSTABILITY. ...CO TO SRN HIGH PLAINS... TYPICAL HIGH-BASED CONVECTION SHOULD INCREASE ACROSS THE HIGHER TERRAIN OF CO/NM THIS AFTERNOON...PERHAPS AIDED BY A COUPLE OF WEAK MID/UPPER LEVEL DISTURBANCES UNDERCUTTING THE RIDGE AXIS ACROSS THE FOUR CORNERS REGION. WEAK SELY UPSLOPE FLOW AND SOME MOISTENING ALONG RESIDUAL FRONT ON THE WRN FLANK OF DEPARTING SURFACE ANTICYCLONE SHOULD AID IN STORMS DEVELOPING EAST INTO AN EVEN MORE FAVORABLE REGIME CHARACTERIZED BY MLCAPE OF 500-1000 J/KG AND ABOUT 30KT DEEP-LAYER SHEAR. A FEW SUPERCELLS OR PERSISTENT MULTICELLS MAY POSE A THREAT OF HAIL AND LOCALLY HIGH WINDS FROM ERN CO SWD ACROSS ERN NM THROUGH THE LATE AFTERNOON/EARLY EVENING. THIS ACTIVITY MAY CONGEAL INTO ONE OR TWO SMALL MCS/S WITH HAIL AND WIND POTENTIAL CONTINUING INTO WRN KS...NWRN TX/OK...INTO THE EVENING/OVERNIGHT. ...MID MS VALLEY/MIDWEST... COLD AIR ALOFT AND DCVA ON THE POLEWARD SIDE OF CYCLONICALLY CURVED MID/UPPER JET MAX WILL PROVIDE WEAK ASCENT AND DESTABILIZATION FROM ERN MO ACROSS THE MIDWEST TODAY AS LARGE OCCLUDED CYCLONE LIFTS FROM THE GREAT LAKES INTO CANADA. MAJORITY OF GUIDANCE SUGGESTS THAT LOW-TOPPED TSTMS SHOULD DEVELOP WITHIN A NW-SE AXIS FROM SERN IA ACROSS ERN MO TO CNTRL/SRN IL BY LATE AFTERNOON. SHEAR AND LIFT WITHIN THIS CORRIDOR MAY BECOME SUFFICIENT TO SUSTAIN A FEW PERSISTENT STORMS WHERE MLCAPE IS FORECAST TO REMAIN BELOW 500 J/KG. SPC ENSEMBLE HAIL GUIDANCE FROM MOST FORECAST SOUNDINGS ACROSS THE REGION SUGGESTS THAT HAIL SIZE POTENTIAL WILL REMAIN BELOW SEVERE CRITERIA. ...RED RIVER/ARKLATEX... THERE IS SOME INDICATION IN STORM SCALE GUIDANCE AND MORNING MODELS THAT LATE AFTERNOON CONVECTION MAY DEVELOP ALONG RESIDUAL/RETREATING FRONTAL ZONE ALONG THE RED RIVER...FROM NERN TX INTO AR. THIS DEVELOPMENT MAY BE AIDED BY AN APPROACHING MCV ACROSS NWRN TX ATTM...AS WELL AS LARGE SCALE ASCENT IN THE ENTRANCE REGION OF MID/UPPER JET ACROSS THE MIDWEST/MS VALLEY. AIRMASS ALONG THE RETREATING BOUNDARY SHOULD BECOME STRONGLY UNSTABLE ON THE EDGE OF THE CAP WITH MLCAPE AOA 2000 J/KG POSSIBLE. DEEP-LAYER UNIDIRECTIONAL SHEAR WOULD SUPPORT STORM ORGANIZATION AND THE POSSIBILITY OF SUPERCELLS OR LINE SEGMENTS FORMING WITH TIME. OVERALL COVERAGE OF THE THREAT AND UNCERTAINTIES REGARDING DEEPER STRONGER ASCENT ACROSS THIS REGION PRECLUDES HIGHER /SLGT RISK/ PROBS AT THIS TIME. HOWEVER...A SMALL SLGT MAY NEED TO BE INTRODUCED BY 20Z IF CONVECTIVE TRENDS WARRANT.
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_2000.html
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