210 ACUS01 KWNS 070047 SWODY1 SPC AC 070045 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0645 PM CST WED MAR 06 2013 VALID 070100Z - 071200Z ...NO SVR TSTM AREAS FORECAST... ...NRN CALIFORNIA INTO THE NRN INTERMOUNTAIN REGION/ROCKIES... THE RISK FOR THUNDERSTORM ACTIVITY APPEARS TO HAVE DIMINISHED ACROSS NORTHERN CALIFORNIA WITH THE ONSET OF MID-LEVEL HEIGHT RISES AND WARMING. THIS IS IN THE WAKE OF A SIGNIFICANT SHORT WAVE IMPULSE NOW MIGRATING ACROSS THE NORTHERN INTERMOUNTAIN REGION...TOWARD THE NORTHERN ROCKIES...WHICH CONTINUES TO SUPPORT SCATTERED WEAK THUNDERSTORMS. ACTIVITY HAS BECOME MOST CONCENTRATED WITHIN THE LEFT EXIT REGION OF AN ASSOCIATED CYCLONIC MID-LEVEL SPEED MAXIMUM...ACROSS PARTS OF EASTERN WASHINGTON/NORTHERN IDAHO AND WESTERN MONTANA. BUT...EVEN HERE...SURFACE COOLING DURING THE NEXT HOUR OR SO PROBABLY WILL RESULT IN INCREASINGLY NEGLIGIBLE RISK FOR ADDITIONAL THUNDERSTORMS BY AROUND 02-03Z. ..KERR.. 03/07/2013  953 ACUS01 KWNS 070540 SWODY1 SPC AC 070538 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1138 PM CST WED MAR 06 2013 VALID 071200Z - 081200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LARGE-SCALE UPPER TROUGHING...CURRENTLY EXTENDING ALONG A POSITIVELY TILTED AXIS FROM THE PACIFIC NORTHWEST INTO THE EASTERN PACIFIC...APPEARS LIKELY TO TAKE ON MORE OF A NEGATIVE TILT...AS A STRONG SHORT WAVE IMPULSE DIGGING INTO ITS BASE GRADUALLY TURNS EASTWARD TOWARD THE SOUTHERN CALIFORNIA COAST LATER TODAY AND TONIGHT. AT THE SAME TIME...DOWNSTREAM UPPER RIDGING IS EXPECTED TO CONTINUE TO BUILD ACROSS THE PLAINS INTO THE MISSISSIPPI VALLEY...WHILE UPPER TROUGHING LINGERS ACROSS THE ATLANTIC SEABOARD INTO THE WESTERN ATLANTIC...AS ANOTHER SHORT WAVE IMPULSE DIGS SOUTHEAST OF THE LOWER GREAT LAKES REGION. IN RESPONSE TO THIS DEVELOPING UPPER PATTERN...AND ASSOCIATED SURFACE PRESSURE FALLS ACROSS THE CENTRAL/SOUTHERN HIGH PLAINS...SOUTHERLY LOW-LEVEL FLOW IS EXPECTED TO STRENGTHEN ACROSS THE LOWER RIO GRANDE VALLEY INTO THE PLAINS. THIS MAY BE ACCOMPANIED BY AT LEAST A WEAK TO MODEST MOISTURE RETURN OFF THE SOUTHWESTERN GULF OF MEXICO...WITH 1.25+ INCH PRECIPITABLE WATER REACHING SOUTHERN TEXAS BY 12Z FRIDAY. HOWEVER...DESPITE THE MOISTENING AT LOW-LEVELS...GUIDANCE REMAINS SUGGESTIVE THAT COINCIDING WARMING ALOFT WILL BE INHIBITIVE TO DEEP CONVECTIVE DEVELOPMENT ACROSS MUCH OF THE CENTRAL AND SOUTHERN PLAINS. ACROSS THE WEST...GENERALLY COOL AND/OR DRY LOW-LEVEL CONDITIONS SHOULD PRECLUDE APPRECIABLE DESTABILIZATION...AND THUNDERSTORM PROBABILITIES APPEAR LESS THAN THE MINIMUM 10 PERCENT THRESHOLD FOR A CATEGORICAL THUNDERSTORM OUTLOOK IN MOST AREAS. ONE EXCEPTION MAY BE COASTAL AREAS OF CENTRAL AND SOUTHERN CALIFORNIA. EVEN HERE...THOUGH...INLAND THUNDERSTORM PROBABILITIES MAY NOT BE MUCH MORE THAN 10 PERCENT...DUE TO GENERALLY WEAK LOW-LEVEL ONSHORE FLOW...AND THE OVERNIGHT TIMING OF ARRIVAL OF THE MID-LEVEL COLD CORE. ..KERR/ROGERS.. 03/07/2013  035 ACUS02 KWNS 070545 SWODY2 SPC AC 070543 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1143 PM CST WED MAR 06 2013 VALID 081200Z - 091200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SOUTHERN HIGH PLAINS... ...SOUTHERN/CENTRAL HIGH PLAINS... LATEST SHORT RANGE MODEL GUIDANCE IS IN GENERAL AGREEMENT REGARDING THE EJECTION OF LEAD SPEED MAX ACROSS NRN MEXICO TOWARD THE TX SOUTH PLAINS BY 09/00Z. THIS FEATURE IS EXPECTED TO SHARPEN THE DRYLINE WHICH WILL EXTEND FROM A LEE CYCLONE OVER SERN CO...SWD ALONG THE TX/NM BORDER INTO THE BIG BEND REGION. LLJ WILL RESPOND TO THE APPROACHING MID LEVEL SPEED MAX AND FAVORABLE BOUNDARY LAYER TRAJECTORIES ARE EXPECTED TO ALLOW MODIFIED LOW LEVEL MOISTURE TO ADVANCE NWD ACROSS THE WRN GULF BASIN INTO THE TX SOUTH PLAINS BY PEAK HEATING. MODELS REMAIN CONSISTENT REGARDING THE LIKELIHOOD FOR LOW 50S SFC DEW POINTS TO RETURN ACROSS THE ERN TX PANHANDLE WHILE 45-50F DEW POINTS COULD BE IN PLACE NEAR THE DRYLINE BY 21Z. IT APPEARS THE STRONGEST BOUNDARY LAYER HEATING WILL OCCUR ACROSS FAR WEST TX INTO ERN NM AND FORECAST CONVECTIVE TEMPERATURES ARE AROUND 65-70F. 23Z SOUNDING FOR DHT EXHIBITS A STRONG VEERING WIND PROFILE WITH HEIGHT AND MUCAPE ON THE ORDER OF 1000 J/KG WITH VERY WEAK INHIBITION. ALTHOUGH PW VALUES ARE SOMEWHAT LOW ACROSS THIS REGION IT APPEARS ISOLATED TSTMS...POSSIBLY SUPERCELLS...WILL EVOLVE BY EARLY EVENING FROM SERN CO...ARCING SSEWD INTO THE TX SOUTH PLAINS. LARGE HAIL IS THE MOST LIKELY SEVERE THREAT...ALTHOUGH CLOUD BASES MAY BE NO HIGHER THAN 1KM DUE TO RELATIVE LOW TEMPERATURE/DEW POINT SPREADS. FOR THIS REASON CAN NOT RULE OUT A FEW TORNADOES. WITH LLJ EXPECTED TO REMAIN STRONG THROUGH THE NIGHT IT WOULD SEEM LIKELY THAT A LOOSELY ORGANIZED LINE OF CONVECTION MAY PROPAGATE INTO WRN OK AND ACROSS WRN/CNTRL KS DURING THE OVERNIGHT HOURS. THIS ACTIVITY WILL BE INCREASINGLY ELEVATED WITH TIME AND SEVERE THREAT SHOULD WANE WITH LOSS OF DAYTIME HEATING. ..DARROW.. 03/07/2013  887 ACUS03 KWNS 070759 SWODY3 SPC AC 070758 DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0158 AM CST THU MAR 07 2013 VALID 091200Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF TX... ...SOUTHERN AND CENTRAL PLAINS... POSITIVE TILTED BUT BI-MODAL UPPER TROUGH WILL PROGRESS ACROSS THE SRN ROCKIES INTO THE PLAINS STATES SATURDAY. LEAD SPEED MAX WILL EJECT ACROSS THE TX PANHANDLE MID DAY WITH A LATE AFTERNOON POSITION OVER NWRN OK. IN RESPONSE TO THIS FEATURE...SFC LOW OVER SWRN KS MAY INTENSIFY BRIEFLY BEFORE EJECTING NEWD DURING THE LATTER HALF OF THE PERIOD. THERE IS SOME CONCERN FOR LOW TOPPED THUNDERSTORMS IMMEDIATELY AHEAD OF THE SFC LOW AND PERHAPS EVEN ALONG ADVANCING DRYLINE/PACIFIC COLD FRONT WHERE A NARROW AXIS OF INSTABILITY SHOULD DEVELOP DUE TO STEEPENING LAPSE RATES ALONG WRN EDGE OF LOWER 50S SFC DEW POINTS. FORECAST SOUNDINGS EXHIBIT LITTLE MORE THAN A FEW HUNDRED J/KG OF MUCAPE BUT LARGE SCALE FORCING WILL PROVE FAVORABLE ACROSS KS ALONG NOSE OF STRONGEST LOW LEVEL HEATING. GIVEN THE LIMITED INSTABILITY WILL ONLY INTRODUCE 5 PERCENT SEVERE PROBS FOR THE POSSIBILITY OF DAMAGING WINDS OR PERHAPS AN ISOLATED TORNADO. FARTHER SOUTH ACROSS CNTRL TX...INSTABILITY WILL BE NOTABLY HIGHER ACROSS THIS REGION WITH PERHAPS MUCAPE APPROACHING 1000 J/KG ACROSS PORTIONS OF THE HILL COUNTRY. TSTMS MAY STRUGGLE TO DEVELOP ALONG THE COLD FRONT UNTIL AFTER DARK WHEN INFLUENCE OF SWRN SPEED MAX/SHORT-WAVE TROUGH EJECTS INTO THE BIG BEND REGION. FRONTAL CONVERGENCE WILL PROVE INSTRUMENTAL IN CONVECTIVE DEVELOPMENT/ORGANIZATION. HAIL AND PERHAPS SOME DAMAGING WINDS WILL BE THE PRIMARY THREATS WITH TSTMS THAT DEVELOP SOUTH OF THE RED RIVER. ..DARROW.. 03/07/2013  593 ACUS48 KWNS 070927 SWOD48 SPC AC 070926 DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0326 AM CST THU MAR 07 2013 VALID 101200Z - 151200Z ...DISCUSSION... SRN SPEED MAX WITHIN THE BASE OF POSITIVE TILTED LONG WAVE TROUGH IS EXPECTED TO EJECT ACROSS TX TOWARD THE LOWER MS VALLEY DURING THE DAY4 TIME PERIOD. WHILE THIS FEATURE WILL UNDOUBTEDLY ENHANCE CONVECTION ALONG ADVANCING COLD FRONT THERE IS MODEL CONSISTENCY REGARDING THE SOMEWHAT MARGINAL BOUNDARY LAYER MOISTURE RETURN AHEAD OF THE COLD FRONT. ADDITIONALLY...RELATIVE WEAK LAPSE RATES SHOULD LIMIT WARM SECTOR INSTABILITY TO A FEW HUNDRED J/KG. GIVEN THE FORECAST SOUNDINGS ACROSS ERN TX/LA THERE IS SOME CONCERN FOR A FEW SEVERE THUNDERSTORMS ALONG A POTENTIAL FRONTAL SQUALL LINE. HOWEVER...MARGINAL FORECAST INSTABILITY WILL LIMIT PREDICTABILITY AND SEVERE PROBS WILL REMAIN LESS THAN 30 PERCENT THIS PERIOD. CONVECTIVE THREAT IS EXPECTED TO SPREAD ACROSS THE REMAINDER OF THE GULF STATES DURING THE DAY5-6 TIME FRAME. IF INSTABILITY IS GREATER THAN CURRENTLY EXPECTED THEN SEVERE PROBS WILL BE ADJUSTED ACCORDINGLY IN LATER OUTLOOKS. ..DARROW.. 03/07/2013  596 ACUS01 KWNS 071201 SWODY1 SPC AC 071159 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0559 AM CST THU MAR 07 2013 VALID 071300Z - 081200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... IN THE WEST...AN UPPER-LEVEL LOW AND ASSOCIATED TROUGH WILL MOVE SLOWLY SEWD OFF OF THE CA COAST. MEANWHILE...IN THE EAST...A POWERFUL LOW PRESSURE SYSTEM OFF OF THE MID-ATLANTIC COAST WILL CONTINUE MOVING NEWD AS A SECONDARY UPPER SYSTEM DIGS INTO THE ERN GREAT LAKES REGION. BETWEEN THESE SYSTEMS ACROSS THE MIDWEST...AN UPPER RIDGE WILL REMAIN IN PLACE. AT THE SURFACE...LOW PRESSURE IN THE LEE OF THE ROCKIES WILL BEGIN TO DRAW MOISTURE NWD FROM THE GULF OF MEXICO...BUT THIS MOISTURE WILL MAKE LITTLE PROGRESS ON D1/THU. GENERALLY DRY AND STABLE CONDITIONS WILL PREVAIL ACROSS THE CONUS...WITH A MINIMAL THUNDERSTORM THREAT CONFINED TO NEAR AND OFF OF THE CA COAST AND NO SEVERE CONVECTION EXPECTED. ...CA COASTAL REGION... WITH THE UPPER LOW EXPECTED TO REMAIN OFFSHORE THROUGH THE PERIOD...ANY THUNDERSTORM THREAT IS EXPECTED TO REMAIN NEAR AND OFF OF THE CA COAST...IN CLOSER PROXIMITY TO STRONGER ASCENT AND COLDER MIDLEVEL TEMPS. EVEN IN THIS AREA...WEAK MUCAPE AOB 200 J/KG AND RELATIVELY WARM EL TEMPS WILL LIKELY KEEP THUNDERSTORM COVERAGE ISOLATED AT BEST. ..DEAN/MEAD.. 03/07/2013  411 ACUS01 KWNS 071600 SWODY1 SPC AC 071558 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0958 AM CST THU MAR 07 2013 VALID 071630Z - 081200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... A CLOSED LOW WILL CONTINUE TO DIG SEWD JUST OFF THE CENTRAL/SRN CA COASTS THROUGH 12Z FRIDAY. A RELATIVELY DRY AIR MASS PERSISTS INLAND...WHILE WEAK BUOYANCY WILL BE POSSIBLE NEAR THE COAST WITH GREATER LOW-LEVEL MOISTURE AND IN CLOSER PROXIMITY TO THE MIDLEVEL COLD CORE AND ZONE OF ASCENT IMMEDIATELY PRECEDING THE LOW. THUS...ISOLATED LOW-TOPPED THUNDERSTORMS WILL BE POSSIBLE LATE THIS AFTERNOON/EVENING ALONG THE CENTRAL CA COAST...AND TONIGHT ALONG THE SRN CA COAST. FARTHER E AND NE...MOISTURE/INSTABILITY WILL REMAIN TOO LIMITED FOR MORE THAN JUST AN ISOLATED LIGHTNING STRIKE OR TWO ACROSS THE GREAT BASIN AND LOWER CO RIVER VALLEY. SOME MIDLEVEL MOISTENING AND WEAK DESTABILIZATION IS EXPECTED LATE TONIGHT ACROSS SE AZ IN ADVANCE OF THE SRN CA MIDLEVEL LOW. HOWEVER...THIS WILL OCCUR VERY LATE IN THE PERIOD /09-12Z/...AND THE OVERALL THUNDERSTORM RISK APPEARS TOO MARGINAL TO ADD AN AREA IN THIS OUTLOOK. OTHERWISE...A RIDGE ALOFT COVERS THE CENTRAL CONUS...IN THE WAKE OF A DEEP ATLANTIC COAST CYCLONE THAT CONTINUES TO MOVE OFFSHORE. WEAK LEE CYCLOGENESIS IS UNDERWAY ACROSS THE CENTRAL/SRN HIGH PLAINS...AND THIS WILL INDUCE RETURN FLOW OF A MODIFYING POST-FRONTAL AIR MASS INTO S/CENTRAL TX BY EARLY FRIDAY. THE COMBINATION OF MODEST MOISTURE AND A WARM ELEVATED MIXED LAYER WILL LIMIT BUOYANCY AND ANY THREAT FOR DEEP CONVECTION ACROSS TX. ONE POSSIBLE EXCEPTION WILL BE ACROSS W/NW KS TONIGHT...WHERE MOISTURE FROM THE TOP OF THIS AFTERNOON/S BOUNDARY LAYER WILL SPREAD NEWD FROM THE SRN HIGH PLAINS...IN A STEEP LAPSE RATE ENVIRONMENT. STILL...ANY BUOYANCY WILL BE QUITE MARGINAL AND ROOTED AOA THE 600 MB LEVEL...WHICH SUGGESTS THAT ANY THUNDERSTORM RISK WILL BE VERY MARGINAL AT BEST...GIVEN THE MEAGER MOISTURE PROFILES. ..THOMPSON/GRAMS.. 03/07/2013  463 ACUS02 KWNS 071714 SWODY2 SPC AC 071712 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1112 AM CST THU MAR 07 2013 VALID 081200Z - 091200Z ...THERE IS A SLGT RISK OF SVR TSTMS SOUTHERN HIGH PLAINS... ...SOUTHERN/CENTRAL HIGH PLAINS... SHORT TERM FORECAST GUIDANCE CONTINUES TO INDICATE MODEST MOISTURE RETURN ON INCREASING S/SELY LOW LEVEL FLOW AHEAD OF A DRYLINE EXTENDING SWD FROM LEE CYCLONE OVER SE CO INTO SW TX. DEWPOINTS NEAR 50 F TO THE MID 50S F ARE EXPECTED NEAR AND EAST OF THE DRYLINE FROM THE ERN TX SOUTH PLAINS INTO WRN OK AND CENTRAL KS. AS APPROACHING SPEED MAX OVER NM OVERSPREADS THE REGION...SLY LOW LEVEL JET WILL INCREASE AND VERTICALLY VEERING PROFILES ARE EXPECTED BY LATE AFTERNOON. ISOLATED SUPERCELL THUNDERSTORMS MAY DEVELOP ALONG/NEAR THE DRYLINE BY 00Z AS EML ERODES AND STEEPENING LAPSE RATES RESULT IN MUCAPE VALUES FROM 500-1000 J/KG. LARGE HAIL AND ISOLATED STRONG WIND GUSTS WILL BE THE MAIN SEVERE THREAT INTO THE EARLY EVENING. HOWEVER...GIVEN FAVORABLE HODOGRAPHS AND RELATIVELY MOIST BOUNDARY LAYER...A TORNADO OR TWO CAN NOT BE RULED OUT. AS COMPOSITE DRYLINE/PACIFIC FRONT SURGES EWD OVERNIGHT...THUNDERSTORMS MAY DEVELOP INTO A SEMI-ORGANIZED/BROKEN LINE ACROSS PARTS OF WRN INTO CENTRAL KS AND WRN OK. THESE STORMS WILL BECOME INCREASINGLY ELEVATED AS BOUNDARY LAYER STABILIZES WITH DIURNAL COOLING. HOWEVER...STEEP MID LEVEL LAPSE RATES AND COOL TEMPERATURES ALOFT MAY MAINTAIN A MARGINAL HAIL THREAT DURING THE NIGHTTIME HOURS. ..LEITMAN/GOSS.. 03/07/2013  721 ACUS01 KWNS 071928 SWODY1 SPC AC 071925 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0125 PM CST THU MAR 07 2013 VALID 072000Z - 081200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... THE PREVIOUS OUTLOOK IS ON TRACK WITH ONLY ISOLATED THUNDERSTORMS POSSIBLE ALONG THE CENTRAL AND SOUTHERN CA COAST THIS AFTERNOON AND TONIGHT. PLEASE REFER TO PREVIOUS DISCUSSION FOR FURTHER DETAILS. ..LEITMAN.. 03/07/2013 .PREV DISCUSSION... /ISSUED 0958 AM CST THU MAR 07 2013/ ...SYNOPSIS... A CLOSED LOW WILL CONTINUE TO DIG SEWD JUST OFF THE CENTRAL/SRN CA COASTS THROUGH 12Z FRIDAY. A RELATIVELY DRY AIR MASS PERSISTS INLAND...WHILE WEAK BUOYANCY WILL BE POSSIBLE NEAR THE COAST WITH GREATER LOW-LEVEL MOISTURE AND IN CLOSER PROXIMITY TO THE MIDLEVEL COLD CORE AND ZONE OF ASCENT IMMEDIATELY PRECEDING THE LOW. THUS...ISOLATED LOW-TOPPED THUNDERSTORMS WILL BE POSSIBLE LATE THIS AFTERNOON/EVENING ALONG THE CENTRAL CA COAST...AND TONIGHT ALONG THE SRN CA COAST. FARTHER E AND NE...MOISTURE/INSTABILITY WILL REMAIN TOO LIMITED FOR MORE THAN JUST AN ISOLATED LIGHTNING STRIKE OR TWO ACROSS THE GREAT BASIN AND LOWER CO RIVER VALLEY. SOME MIDLEVEL MOISTENING AND WEAK DESTABILIZATION IS EXPECTED LATE TONIGHT ACROSS SE AZ IN ADVANCE OF THE SRN CA MIDLEVEL LOW. HOWEVER...THIS WILL OCCUR VERY LATE IN THE PERIOD /09-12Z/...AND THE OVERALL THUNDERSTORM RISK APPEARS TOO MARGINAL TO ADD AN AREA IN THIS OUTLOOK. OTHERWISE...A RIDGE ALOFT COVERS THE CENTRAL CONUS...IN THE WAKE OF A DEEP ATLANTIC COAST CYCLONE THAT CONTINUES TO MOVE OFFSHORE. WEAK LEE CYCLOGENESIS IS UNDERWAY ACROSS THE CENTRAL/SRN HIGH PLAINS...AND THIS WILL INDUCE RETURN FLOW OF A MODIFYING POST-FRONTAL AIR MASS INTO S/CENTRAL TX BY EARLY FRIDAY. THE COMBINATION OF MODEST MOISTURE AND A WARM ELEVATED MIXED LAYER WILL LIMIT BUOYANCY AND ANY THREAT FOR DEEP CONVECTION ACROSS TX. ONE POSSIBLE EXCEPTION WILL BE ACROSS W/NW KS TONIGHT...WHERE MOISTURE FROM THE TOP OF THIS AFTERNOON/S BOUNDARY LAYER WILL SPREAD NEWD FROM THE SRN HIGH PLAINS...IN A STEEP LAPSE RATE ENVIRONMENT. STILL...ANY BUOYANCY WILL BE QUITE MARGINAL AND ROOTED AOA THE 600 MB LEVEL...WHICH SUGGESTS THAT ANY THUNDERSTORM RISK WILL BE VERY MARGINAL AT BEST...GIVEN THE MEAGER MOISTURE PROFILES.