The SPC is forecasting ...an outbreak of severe thunderstorms and tornadoes is expected over parts of the central plains this afternoon and tonight.... Please read the latest public statement about this event. View What is a Watch? clip.
| Categorical Graphic |
|---|
|
| Probabilistic Tornado 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. |
| Probabilistic Damaging Wind 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. |
| Probabilistic Large Hail 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. |
SPC AC 141245
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0745 AM CDT SAT APR 14 2012
VALID 141300Z - 151200Z
...THERE IS A HIGH RISK OF SVR TSTMS LATER THIS AFTERNOON INTO
TONIGHT FOR CENTRAL/ERN NEB...CENTRAL/ERN KS...AND CENTRAL/N CENTRAL
OK...
...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK...FROM
SW OK TO FAR NE NEB AND WRN IA...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK...FROM
NW TX TO WRN NEB...IA...AND MO...
...TORNADO OUTBREAK EXPECTED LATE THIS AFTERNOON INTO TONIGHT FROM
CENTRAL/ERN NEB SWD ACROSS KS TO CENTRAL OK...WITH THE POTENTIAL FOR
LONG-TRACK/DAMAGING TORNADOES...
...SYNOPSIS...
A CLOSED LOW OVER NW AZ THIS MORNING WILL PROGRESS EWD/ENEWD TO THE
HIGH PLAINS BY THIS EVENING WHILE EVOLVING INTO MORE OF AN OPEN
WAVE...AND THEN CONTINUE INTO THE CENTRAL PLAINS BY THE END OF THE
PERIOD. AN ASSOCIATED SURFACE CYCLONE WILL DEEPEN AND MOVE NEWD
FROM ERN CO THIS AFTERNOON TO NE NEB/SE SD BY 12Z SUNDAY. S OF THE
CYCLONE...A WELL-DEFINED DRYLINE IS EXPECTED TO RESIDE FROM CENTRAL
KS SWD INTO WRN OK AND NW TX BY THIS EVENING...WHILE A WARM FRONT
MOVES NWD FROM KS THIS MORNING TO CENTRAL/ERN NEB BY LATE AFTERNOON.
A MOIST AND UNSTABLE WARM SECTOR WILL COVER NEB/KS/OK/N TX TO THE E
OF THE DRYLINE AND S OF THE WARM FRONT. THE PRIMARY LOCATIONS FOR
SEVERE STORM DEVELOPMENT TODAY WILL BE NEAR THE SURFACE LOW MOVING
INTO NEB...AND THE DRYLINE TRAILING SWD INTO KS/OK.
...CENTRAL PLAINS THROUGH TONIGHT...
THE FORECAST REASONING REMAINS LARGELY UNCHANGED FROM THE PAST FEW
DAYS. IN THE WAKE OF MORNING WAA STORMS ACROSS NE OK/SE KS/SW
MO...LOW-LEVEL MOISTURE WILL SURGE NWD ACROSS KS TO S CENTRAL/SE NEB
BY MID-LATE AFTERNOON. DAYTIME HEATING INVOF THE DRYLINE AND
BOUNDARY LAYER DEWPOINTS RANGING FROM THE LOW 60S IN NEB TO THE
MID-UPPER 60S IN CENTRAL OK WILL CONTRIBUTE TO AFTERNOON MLCAPE
VALUES OF 2000-3500 J/KG. MEANWHILE... DEEP-LAYER VERTICAL SHEAR
WILL BE QUITE SUPPORTIVE OF SUPERCELLS IN THE UNSTABLE WARM
SECTOR...WITH EFFECTIVE BULK SHEAR OF 50-70 KT ACROSS ALMOST THE
ENTIRE WARM SECTOR. THE DEGREE OF LOW-LEVEL MOISTURE AND AN
EXPECTED INCREASE IN LOW-LEVEL SHEAR LATER THIS AFTERNOON INTO EARLY
TONIGHT WILL RESULT IN AN ENVIRONMENT CLEARLY INTO THE PARAMETER
SPACE ASSOCIATED WITH PREVIOUS STRONG-VIOLENT AND LONG-TRACK TORNADO
EPISODES.
THE PRIMARY QUESTION THIS OUTLOOK WILL BE STORM COVERAGE ALONG THE
DRYLINE THIS EVENING IN KS/OK. THE CONVECTIVE SCHEMES IN THE
OPERATIONAL MODELS VARY WITH STORM INITIATION SIGNALS...WHILE
SEVERAL OF THE CONVECTION-ALLOWING MODELS GENERATE WIDELY SCATTERED
DRYLINE SUPERCELLS IN THE 22-01Z TIME FRAME. FORECAST
SOUNDINGS...MODIFIED FOR EXPECTED AFTERNOON TEMPERATURES ALONG THE
DRYLINE...SHOW DEEP MIXED LAYER AND LITTLE OR NO CONVECTIVE
INHIBITION. PLUS...A WELL-DEFINED BAND OF LOW-LEVEL ASCENT IS
EXPECTED ALONG THE DRYLINE...WHICH SUGGESTS AT LEAST
WIDELY-SCATTERED THUNDERSTORM DEVELOPMENT ACROSS THE KS/OK PORTION
OF THE DRYLINE IS ENTIRELY PLAUSIBLE. FARTHER N...POTENTIALLY MORE
CONCENTRATED STORM DEVELOPMENT IS EXPECTED NEAR THE SURFACE LOW AND
NW EDGE OF THE UNSTABLE WARM SECTOR IN NEB /WITHIN THE LEFT EXIT
REGION OF THE JET ALOFT/. ALL FACTORS FAVOR DISCRETE CONVECTIVE
MODES THROUGH EARLY TONIGHT...AND THOUGH STORMS COULD BE WIDELY
SPACED...THEY WILL BE CAPABLE OF PRODUCING LONG PATHS OF VERY LARGE
HAIL AND DAMAGING TORNADOES THROUGH AT LEAST 06Z.
LATE TONIGHT...THE MIDLEVEL TROUGH WILL FULLY EMERGE OVER THE PLAINS
AND THE PACIFIC COLD FRONT WILL OVERTAKE THE DRYLINE...POTENTIALLY
SUPPORTING MORE EXTENSIVE SQUALL LINE DEVELOPMENT NEAR OR AFTER 06Z.
DAMAGING WINDS WILL BE MORE OF A THREAT WITH THE MORE LINEAR AND
WIDESPREAD CONVECTION LATE TONIGHT...GIVEN A CONTINUATION OF
SURFACE-BASED INSTABILITY AND 60-70 KT FLOW IN THE LOWEST FEW
THOUSAND FEET AGL.
..THOMPSON/MOSIER.. 04/14/2012
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z