May 15, 2015 2000 UTC Day 1 Convective Outlook
Updated: Fri May 15 19:54:18 UTC 2015 (20150515 2000Z Day 1 shapefile | 20150515 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150515 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 27,805 128,716 Scottsbluff, NE...Torrington, WY...
SLIGHT 183,631 2,394,192 Lubbock, TX...Amarillo, TX...Midland, TX...Odessa, TX...Rapid City, SD...
MARGINAL 238,486 16,283,474 Houston, TX...Omaha, NE...Wichita, KS...Lincoln, NE...Des Moines, IA...
Probabilistic Tornado Graphic
20150515 2000 UTC Day 1 Tornado Probabilities Graphic
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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 32,890 165,134 Scottsbluff, NE...Sterling, CO...Torrington, WY...
2 % 60,854 2,018,595 Fort Collins, CO...Greeley, CO...Cheyenne, WY...Lake Jackson, TX...North Platte, NE...
Probabilistic Damaging Wind Graphic
20150515 2000 UTC Day 1 Damaging Wind Probabilities Graphic
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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
30 % 27,923 128,834 Scottsbluff, NE...Torrington, WY...
15 % 183,038 2,393,495 Lubbock, TX...Amarillo, TX...Midland, TX...Odessa, TX...Rapid City, SD...
5 % 239,076 16,236,317 Houston, TX...Omaha, NE...Wichita, KS...Lincoln, NE...Des Moines, IA...
Probabilistic Large Hail Graphic
20150515 2000 UTC Day 1 Large Hail Probabilities Graphic
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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
30 % 27,797 127,198 Scottsbluff, NE...Torrington, WY...
15 % 183,175 2,395,078 Lubbock, TX...Amarillo, TX...Midland, TX...Odessa, TX...Rapid City, SD...
5 % 131,693 3,929,526 Omaha, NE...Wichita, KS...Lincoln, NE...Sioux Falls, SD...Fort Collins, CO...
   SPC AC 151954

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0254 PM CDT FRI MAY 15 2015

   VALID 152000Z - 161200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS LATE THIS AFTERNOON AND EVENING
   ACROSS PARTS OF SOUTHEAST WYOMING...SOUTHERN SOUTH DAKOTA AND
   WESTERN NEBRASKA...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SURROUNDING NORTH
   CENTRAL HIGH PLAINS...AND SOUTHWARD ACROSS THE CENTRAL INTO SOUTHERN
   HIGH PLAINS FOR LATE THIS EVENING INTO THE OVERNIGHT HOURS...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS SURROUNDING AREAS OF THE
   CENTRAL AND SOUTHERN PLAINS...AND ACROSS PARTS OF THE MID MISSOURI
   INTO MIDDLE MISSISSIPPI VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS LATE THIS AFTERNOON ACROSS
   PARTS OF TEXAS COASTAL AREAS...

   ...SUMMARY...
   SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING ACROSS
   PARTS OF THE NORTH CENTRAL HIGH PLAINS...WHERE LARGE HAIL...DAMAGING
   GUSTS...AND A COUPLE OF TORNADOES ARE POSSIBLE.  ADDITIONAL STRONG
   TO SEVERE STORMS ARE POSSIBLE ACROSS PARTS OF THE CENTRAL AND
   SOUTHERN HIGH PLAINS LATE THIS EVENING OR OVERNIGHT.

   ...20Z OUTLOOK UPDATE...
   ADJUSTMENTS HAVE BEEN MADE TO THE CATEGORICAL AND PROBABILISTIC
   LINES IN AN ATTEMPT TO ACCOUNT FOR ONGOING CONVECTIVE TRENDS AND
   DESTABILIZATION.

   ...LOWER GREAT LAKES/UPPER OHIO VALLEY...
   IT IS APPEARING INCREASINGLY UNLIKELY THAT THERE WILL BE SUFFICIENT
   LOW-LEVEL MOISTENING AND DESTABILIZATION TO SUPPORT AN APPRECIABLE
   SEVERE WEATHER THREAT...BEFORE MODEST VERTICAL SHEAR WEAKENS IN THE
   WAKE OF THE SHORT WAVE IMPULSE MIGRATING THROUGH THE LOWER GREAT
   LAKES REGION.

   ...TEXAS COASTAL AREAS...
   LOW PROBABILITIES FOR SEVERE WIND GUSTS...AND PERHAPS A BRIEF/WEAK
   TORNADO...ARE BEING MAINTAINED FOR VIGOROUS CONVECTIVE DEVELOPMENT
   ALONG AN EASTWARD ADVANCING CONVECTIVELY GENERATED COLD POOL...
   SPREADING TOWARD UPPER TEXAS COASTAL AREAS...AND SOUTHWARD ACROSS
   DEEP SOUTH TEXAS COASTAL AREAS.

   ...MID MISSOURI INTO MIDDLE MISSISSIPPI VALLEY...
   LOCALIZED STRONG WIND GUSTS MAY NOT BE OUT OF THE QUESTION THROUGH
   WITH AN ONGOING ARCING BAND OF STORMS WHICH SHOULD OVERSPREAD THE
   REGION THROUGH THE REMAINDER OF THE AFTERNOON.

   ...HIGH PLAINS...
   NO APPRECIABLE CHANGES HAVE BEEN MADE.  PRIMARY SEVERE THUNDERSTORM
   RISK SHOULD REMAIN FOCUSED ACROSS THE NORTH CENTRAL HIGH PLAINS LATE
   THIS AFTERNOON AND EVENING.  FARTHER SOUTH...ANYTHING MUCH BEYOND
   THE LOWER THRESHOLD SEVERE PROBABILITIES /5 PERCENT/ STILL SEEMS
   LIKELY TO AWAIT FORCING FOR ASCENT ASSOCIATED WITH A SHORT WAVE
   IMPULSE CURRENTLY STILL WEST OF THE SOUTHERN ROCKIES.  THIS MAY NOT
   OCCUR UNTIL AFTER 16/03Z... PERHAPS AFTER 06Z...AT A TIME WHEN
   RADIATIONAL SURFACE COOLING WILL BEGIN IMPACTING BOUNDARY LAYER
   INSTABILITY ALONG THE RETREATING DRYLINE.

   ..KERR.. 05/15/2015

   .PREV DISCUSSION... /ISSUED 1130 AM CDT FRI MAY 15 2015/

   ...CENTRAL HIGH PLAINS THIS AFTERNOON INTO TONIGHT...
   A LARGE-SCALE TROUGH OVER THE SRN GREAT BASIN WILL PROGRESS SLOWLY
   EWD WHILE DOWNSTREAM RIDGING ALOFT PERSISTS OVER THE MS/OH VALLEY
   REGION.  A SERIES OF EMBEDDED SPEED MAXIMA WILL ROTATE EWD AND NWD
   AROUND THE ERN PERIPHERY OF THE TROUGH...WITH ONE SUBTLE SPEED MAX
   TRANSLATING NNEWD OVER CO...AND A STRONGER UPSTREAM WAVE OVER NRN
   BAJA CA THAT WILL REACH THE SRN HIGH PLAINS LATE TONIGHT.  AT THE
   SURFACE...A LEE CYCLONE WILL CONTINUE TO DEEPEN SOME THROUGH THE
   AFTERNOON ACROSS NE CO...AND A WARM FRONT WILL MOVE NWD INTO NEB. 
   THE MOISTURE PATTERN IN THE LOW LEVELS HAS BEEN DISRUPTED BY THE
   EFFECTS OF OVERNIGHT CONVECTION ACROSS KS/OK...WITH SUBSTANTIAL
   DRYING NOTED ACROSS WRN KS.  THIS DRIER LOW-LEVEL AIR WILL SPREAD
   NWD INTO SW NEB TODAY AND WILL TEND TO OFFSET DESTABILIZATION DUE TO
   DAYTIME HEATING...WHILE SOMEWHAT HIGHER DEWPOINTS WILL BE MAINTAINED
   FROM SE NEB INTO ERN KS WHERE SURFACE TEMPERATURES WILL BE SLOWER TO
   WARM AS A RESULT OF LINGER CLOUDS/CONVECTION.

   AS THE SPEED MAX MOVES NNEWD OVER CO...THUNDERSTORM DEVELOPMENT IS
   EXPECTED NEAR AND N OF THE LEE CYCLONE BY EARLY-MID AFTERNOON FROM
   N/NE CO INTO SE WY AND THE NEB PANHANDLE.  BOUNDARY LAYER DEWPOINTS
   IN THE LOW-MID 50S AND SURFACE TEMPERATURES WARMING INTO THE
   70S...BENEATH STEEP MIDLEVEL LAPSE RATES...WILL RESULT IN MODERATE
   BUOYANCY THIS AFTERNOON /MLCAPE VALUES APPROACHING 2000 J PER KG/. 
   COINCIDENT WITH THE DESTABILIZATION...DEEP-LAYER VERTICAL SHEAR WILL
   BECOME FAVORABLE FOR SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL AND
   DAMAGING WINDS.  SOME UPSCALE GROWTH INTO CLUSTERS/LINE SEGMENTS
   WILL BE POSSIBLE BY THIS EVENING AS STORMS OVERSPREAD SW SD. 
   LOW-LEVEL SHEAR AND MOISTURE WILL BE SUFFICIENT FOR A COUPLE OF
   TORNADOES WITH THE MORE DISCRETE SUPERCELLS LATER THIS AFTERNOON.

   ...DRYLINE FROM WRN KS TO THE TX PANHANDLE TONIGHT...
   WHILE ISOLATED/SHORT-LIVED STORMS WILL BE POSSIBLE ALONG THE DIFFUSE
   DRYLINE THIS AFTERNOON FROM WRN KS TO THE ERN TX PANHANDLE...THE
   GREATER RISK FOR MORE WIDESPREAD CONVECTION WILL BE TONIGHT AS A
   PACIFIC COLD FRONT ENCOUNTERS THE RETREATING DRYLINE.  ASCENT OVER
   THE SRN HIGH PLAINS WILL BE AUGMENTED IN THE EXIT REGION OF THE
   SPEED MAX APPROACHING FROM NRN BAJA...AND THE WWD ADVANCE OF THE
   LOW-LEVEL MOISTURE WILL RESULT IN MODERATE BUOYANCY AND ONLY SMALL
   CONVECTIVE INHIBITION...GIVEN THE LACK OF AN UPSTREAM WARM ELEVATED
   MIXED LAYER.  STORMS THAT FORM TONIGHT ALONG THE DRYLINE/COLD FRONT
   WILL SUBSEQUENTLY MOVE EWD/NEWD ACROSS THE TX PANHANDLE AND SW
   KS...WITH AN ATTENDANT RISK FOR AT LEAST ISOLATED LARGE HAIL AND
   DAMAGING GUSTS.

   ...ERN KS/SE NEB/SRN IA/MO THIS AFTERNOON...
   AN MCV WITH ONGOING CONVECTION WILL MOVE NNEWD TOWARD NW MO THROUGH
   THE AFTERNOON.  SURFACE HEATING IN CLOUD BREAKS OVER MO ALONG AND S
   OF A STALLED SURFACE FRONT WILL SUPPORT MLCAPE VALUES NEAR 2000 J/KG
   BASED ON MODIFIED 12Z SOUNDINGS FROM TOP/SGF.  VERTICAL SHEAR WILL
   BE RELATIVELY WEAK...BUT A FEW PULSE-TYPE STORMS WITH MARGINALLY
   SEVERE HAIL AND DOWNBURST WINDS WILL BE POSSIBLE THROUGH THE
   AFTERNOON ACROSS CENTRAL/NRN MO.  ISOLATED HAIL APPROACHING ONE INCH
   IN DIAMETER MAY ALSO OCCUR WITH ELEVATED CONVECTION FARTHER N FROM
   SE NEB INTO SRN IA.

   ...S TX THIS AFTERNOON...
   AN ONGOING MCS OVER S CENTRAL TX WILL LIKELY PERSIST THROUGH THE
   AFTERNOON WHILE DEVELOPING EWD/SEWD INTO A MOIST AND MODERATELY
   UNSTABLE ENVIRONMENT.  VERTICAL SHEAR WILL BE SUFFICIENT FOR SOME
   STORM-SCALE ORGANIZATION...WITH ISOLATED DAMAGING GUSTS AND
   MARGINALLY SEVERE HAIL THE MAIN CONCERNS.

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