High Risk for Tornadoes & Severe Weather in the Plains Today & Tonight (4/14/2012)


A high risk of severe thunderstorms, with long track & violent tornadoes, hail to grapefruit sized and winds to 80 mph are likely this afternoon and evening.

This is one day removed after tornadoes hit Norman, OK with potential EF2 damage, and possible tornadoes earlier this morning along a line from Piedmont to Guthrie, OK including the NW sides of Edmond.

I urge and beg you if you are in the high risk area this, know your plan. Be prepared to move quickly to shelter. I have included the SPC outlook and graphic in this post.

image

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

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s