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| Probabilistic Tornado Graphic | |||||||||
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| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
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| Probabilistic Damaging Wind Graphic | |||||||||
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| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
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| Probabilistic Large Hail Graphic | |||||||||
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
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SPC AC 190559 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1259 AM CDT WED JUN 19 2013 VALID 191200Z - 201200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS CENTRAL AND ERN MT INTO WRN ND THIS AFTERNOON THROUGH TONIGHT... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL AND SRN HIGH PLAINS THIS AFTERNOON AND EVENING... ...SYNOPSIS.. A CLOSED LOW CENTERED ALONG OR JUST OFF THE WA/ORE COASTS PER 19/00Z UPPER AIR ANALYSIS WILL MOVE INLAND TODAY...WHILE A POTENT SHORTWAVE TROUGH MOVES THROUGH THE SRN AND ERN PERIPHERIES OF THIS SYSTEM. THIS LATTER FEATURE WILL ACQUIRE A NEGATIVE-TILT AS IT TRACKS FROM THE NRN GREAT BASIN INTO THE NRN ROCKIES/HIGH PLAINS REGION THIS AFTERNOON THROUGH 12Z THURSDAY. DOWNSTREAM HEIGHT RISES AND MIDLEVEL WARMING WILL OCCUR AS A RIDGE BUILDS EWD ACROSS THE PLAINS. ASIDE FROM THE GREAT LAKES TO NEW ENGLAND...MIDLEVEL WINDS ARE EXPECTED TO WEAKEN AS A TROUGH MOVES OFF THE ERN SEABOARD INTO THE WRN ATLANTIC. A LEE CYCLONE IS FORECAST TO DEEPEN OVER SERN MT THROUGH THE EARLY HALF OF THE FORECAST PERIOD...WITH A LEE TROUGH/DRYLINE EXTENDING SWD THROUGH THE CNTRL AND SRN HIGH PLAINS. A COLD FRONT WILL ACCELERATE EWD ACROSS THE NRN HIGH PLAINS THIS EVENING THROUGH TONIGHT AND SHOULD REACH THE WRN DAKOTAS BY 12Z THURSDAY. ...CENTRAL AND ERN MT INTO WRN ND... SURFACE DEW POINTS IN THE 50S WERE OBSERVED ACROSS MUCH OF CENTRAL AND ERN MT TUESDAY AFTERNOON/EVENING. STRENGTHENING SELY LOW LEVEL WINDS E-N OF THE DEEPENING SERN MT SURFACE LOW WILL SUPPORT FURTHER MOISTURE ADVECTION WITH DEW POINTS IN THE MID-UPPER 50S EXPECTED THIS AFTERNOON ACROSS CENTRAL/NORTH CENTRAL MT AND AROUND 60 IN ERN MT/WRN DAKOTAS. THIS INCREASE IN MOISTURE /I.E. PRECIPITABLE WATER VALUES TO OVER 1 INCH/...SURFACE HEATING AND STEEP LAPSE RATES WILL RESULT IN MLCAPE OF 1500-2500 J/KG...AND POSSIBLY UP TO 3000 J/KG OVER ERN MT AND PART OF THE ADJACENT DAKOTAS. AN INCREASE IN DIFFLUENT FLOW ALOFT ACROSS THE NRN ROCKIES/HIGH PLAINS SUGGESTS INITIAL TSTMS MAY DEVELOP OVER THE HIGHER TERRAIN OF THE NRN ROCKIES WITH THE APPROACH OF THE NEGATIVELY-TILTED SHORTWAVE TROUGH. THESE STORMS ARE EXPECTED TO INCREASE IN INTENSITY AND SEVERE WEATHER THREAT AS THEY TRACK NWD/NEWD INTO CENTRAL MT BY MID-LATE AFTERNOON WHERE THE ENVIRONMENT WILL BE MODERATELY UNSTABLE AND STRONGLY SHEARED. THESE STORMS WILL BE CAPABLE OF PRODUCING LARGE HAIL...SOME VERY LARGE...GIVEN THE PRESENCE OF STEEP LAPSE RATES AND SIZABLE CAPE IN THE -10 TO -30 C LAYER SHOWN IN FORECAST SOUNDINGS WITH THE MORE INTENSE UPDRAFTS /SUPERCELLS/. DAMAGING WINDS WILL BE A THREAT...ESPECIALLY THIS EVENING THROUGH TONIGHT...AS COLD POOLS MERGE WITH CLUSTERS OF STORMS MOVING NEWD/EWD INTO ERN MT/WRN ND...POTENTIALLY EVOLVING INTO A LINEAR MCS. A STRENGTHENING SELY LLJ INTO ERN/NERN MT BY EVENING MAY INCREASE A TORNADO THREAT ACROSS THESE AREAS AS LOW LEVEL SHEAR/HODOGRAPH SIZE INCREASES. ...CENTRAL AND SRN HIGH PLAINS... MUCH OF THE GREAT PLAINS IS EXPECTED TO BECOME MODERATELY TO STRONGLY UNSTABLE TODAY...BUT GIVEN HEIGHT RISES/WARMING MIDLEVEL TEMPERATURES THERE REMAINS UNCERTAINTY WITH THE POTENTIAL DEVELOPMENT OF TSTMS ACROSS A LARGE PORTION OF THE PLAINS. THE EXCEPTION APPEARS TO BE ALONG THE LEE TROUGH/DRY LINE ACROSS THE CENTRAL/SRN HIGH PLAINS...WHERE THE 12Z ECMWF/00Z NAM SUGGEST TSTMS WILL DEVELOP LATER THIS AFTERNOON INTO THE EVENING. MODERATE TO STRONG INSTABILITY AND EFFECTIVE BULK SHEAR TO AT LEAST 40 KT WILL SUPPORT SUPERCELLS. THE PRESENCE OF STEEP LAPSE RATES AND SIZABLE CAPE IN THE -10 TO -30 C LAYER SHOWN IN FORECAST SOUNDINGS WITH THE MORE INTENSE UPDRAFTS /SUPERCELLS/ WILL SUPPORT LARGE HAIL...SOME VERY LARGE. DAMAGING WINDS WILL ALSO BE A THREAT WITH THE STRONGER STORMS. ...DAKOTAS/CENTRAL AND ERN NEB/SWRN MN... ASIDE FROM THE STRONG TO SEVERE STORMS MOVING INTO WRN ND LATER TONIGHT...A STRENGTHENING SLY LLJ UP TO 40-50 KT EXTENDING FROM CENTRAL KS/NEB INTO SD WILL RESULT IN AN INCREASE IN WAA ACROSS THE DAKOTAS...CENTRAL-ERN NEB INTO SWRN MN AFTER DARK. THIS SHOULD PROVE FAVORABLE IN SUPPORTING ELEVATED TSTM DEVELOPMENT...THOUGH COVERAGE MAY BE SOMEWHAT LIMITED GIVEN THE BACKGROUND HEIGHT RISES WITH THE UPPER RIDGE. A RESERVOIR OF MODERATE-STRONG INSTABILITY AND INCREASING EFFECTIVE BULK SHEAR SHOULD SUPPORT A FEW STRONGER TO SEVERE STORMS WITH HAIL AND STRONG WIND GUSTS BEING THE PRIMARY THREATS. GIVEN UNCERTAINTY IN THE OVERALL COVERAGE OF A SEVERE WEATHER THREAT...ONLY LOW SEVERE HAIL/WIND PROBABILITIES WILL BE INCLUDED WITH THIS OUTLOOK. ..PETERS/ROGERS.. 06/19/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z |