[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 050618
SWODY2
SPC AC 050617

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0117 AM CDT WED APR 05 2006

VALID 061200Z - 071200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER A LARGE AREA OF THE CENTRAL
AND SOUTHERN PLAINS FROM NEBRASKA/AND SOUTHWEST IOWA TO EASTERN
NEBRASKA AND OKLAHOMA...MUCH OF MISSOURI AND NORTHWEST ARKANSAS...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM THE SRN/CNTRL PLAINS TO THE OH VALLEY...

...SIGNIFICANT SEVERE WEATHER OUTBREAK APPEARS INCREASINGLY LIKELY
OVER THE PLAINS/MIDWEST ON THURSDAY...

...SYNOPSIS...
VERY ACTIVE WEATHER PATTERN WILL CONTINUE TO EVOLVE WEDNESDAY INTO
THURSDAY WITH THE POTENTIAL FOR WIDESPREAD SEVERE WEATHER DEVELOPING
ACROSS THE PLAINS...AND POSSIBLY SPREADING EAST ACROSS THE MIDWEST
AND OH VALLEY AREAS FROM THURSDAY THROUGH EARLY FRIDAY.

THE SYSTEM EXPECTED TO BRING ABOUT THE NEXT ROUND OF SPRINGTIME
SEVERE WEATHER WAS CROSSING THE WEST COAST IN THE FORM OF A COMPLEX
DOUBLE-VORTEX UPPER TROUGH EARLY TODAY. STRONG DEEP-LAYER ASCENT WAS
OBVIOUS AHEAD OF THE TROUGH AND RADAR AND SATELLITE IMAGERY WERE
INDICATING PRONOUNCED DIFFLUENT MID/UPPER LEVEL FLOW PROMOTING
CONVECTION FROM CA TO ID. UPSTREAM FROM THE WEST COAST TROUGH...
ANOTHER POTENT IMPULSE WAS DEPICTED ON SATELLITE IMAGERY MOVING
SOUTH OF THE GULF OF AK. DESPITE RELATIVELY HIGH AMPLITUDE FLOW
REGIME...CONSIDERABLE JET ENERGY WITH THE UPSTREAM SYSTEM WILL
DISLODGE THE WEST COAST TROUGH INLAND AND ACROSS THE ROCKIES THROUGH
DAY 1. A BELT OF 80-90KT MID LEVEL FLOW OF WILL ROTATE THROUGH THE
BASE OF THE TROUGH AND NOSE OUT ATOP THE SRN/CNTRL HIGH PLAINS
THROUGH 36 HOURS...BY THURSDAY MORNING. STRONG DYNAMIC FORCING
ACCOMPANYING THE UPPER SYSTEM WILL INDUCE LEE-SIDE CYCLOGENESIS
ACROSS WY/MT TONIGHT AND THEN THE DEEPENING SURFACE LOW WILL REFORM
EWD ACROSS NEB THROUGH THURSDAY MORNING. LATEST MODEL FORECASTS
SUGGEST AN OVERALL SCENARIO STRONGER AND SOMEWHAT FURTHER SOUTH WITH
THE CYCLONE THAN MODEL GUIDANCE FROM 24 HOURS AGO. WHILE THIS
SUGGESTS A POSSIBLE TREND...ALL THE LATEST DETERMINISTIC GUIDANCE IS
IN GOOD AGREEMENT WITH TIMING AND INTENSITY OF THE LARGE SCALE
FEATURES TO AFFECT SEVERE WEATHER EVOLUTION FROM THE PLAINS TO THE
MIDWEST ON THURSDAY.

...NEB/IA...
THERE MAY BE AN ARC OF DEEP CONVECTION UNDERWAY EARLY IN THE DAY
FROM NEAR/NORTH OF THE SURFACE LOW...EWD AND SEWD ALONG AND NORTH OF
THE WARM FRONT...FROM NEB/SD...ACROSS IA...AND PERHAPS OVER IL. THIS
ACTIVITY WILL LIKELY BE SUSTAINED BY INTENSIFYING LARGE SCALE
ISENTROPIC LIFT OCCURRING ON THE EDGE OF EXTENSIVE PLAINS CAPPING
INVERSION. WHILE ELEVATED IN NATURE...SOME OF THESE STORMS STILL
PRODUCE HAIL. STRONG CAP ACROSS MUCH OF THE WARM SECTOR WILL AID IN
EFFICIENT LOW LEVEL MOISTURE TRANSPORT NWD ACROSS KS/MO/ERN NEB AND
IA WITH A GENERAL CONSENSUS AMONG AVAILABLE GUIDANCE THAT AT LEAST
LOW 60S F DEWPOINTS SHOULD DEVELOP ACROSS THESE AREAS BY AFTERNOON.
DEEP LAYER WIND FIELDS SURROUNDING THE INTENSIFYING CYCLONE OVER NEB
WILL STRENGTHEN THROUGH THE DAY AS WARM FRONT LIFTS NWD ACROSS ERN
NEB AND MUCH OF IA...AND DRYLINE SHARPENS FROM NEB SWD ACROSS KS/OK.


STRONG ASCENT BENEATH THE NOSE OF THE MID LEVEL JET...AND NEAR
SURFACE LOW/WARM FRONT WILL EFFECTIVELY OVERCOME THE CAP ACROSS
NEB/IA THROUGH AFTERNOON. STEEP MID LEVEL LAPSE RATES OF ABOUT 8
C/KM ATOP MOISTENING BOUNDARY LAYER WILL CONTRIBUTE TO MLCAPE IN THE
RANGE OF 500-1000 J/KG...AND PERHAPS LOCALLY HIGHER IN AREAS WHERE
MOISTURE/HEATING CAN BE MAXIMIZED. ROBUST SURFACE-BASED TSTM
DEVELOPMENT SHOULD COMMENCE AS CAP IS BREACHED ACROSS NEB AND INTO
IA FROM AFTERNOON INTO EVENING. SHEAR WILL BE MORE THAN ADEQUATE FOR
SUPERCELLS AND VERY LARGE HAIL...HIGH WIND...AND TORNADOES APPEAR
LIKELY. TORNADO POTENTIAL WILL DEPEND ON QUALITY OF MOISTURE RETURN
INTO THE AREA...AND SPECIFIC LOCATION OF THE SURFACE LOW....WARM
FRONT...AND MESOSCALE BOUNDARIES. FORECAST SOUNDINGS FROM ERN
NEB...ACROSS THE MO RIVER INTO WRN IA APPEAR TO SUGGEST THAT
CONDITIONS FOR STRONG TORNADOES COULD DEVELOP IN THIS AREA THROUGH
THE THURSDAY EVENING.

...ERN KS/OK...MO...AR...
CLASSIC DRYLINE SURGE WILL DEVELOP EAST FROM KS/OK INTO MO/AR FROM
AFTERNOON THROUGH EVENING. STRONG CAPPING ACROSS LOW LEVEL MOIST
AXIS WILL CONTRIBUTE TO THE DEVELOPMENT OF MODEST INSTABILITY INTO
THE AFTERNOON BEFORE STRONG HEIGHT FALLS AND MIXING ON THE ADVANCING
DRYLINE PROMOTE STORM INITIATION IN MODERATE TO LOCALLY STRONG CAPE
ENVIRONMENT. ALREADY STRONG DEEP LAYER SHEAR WILL INTENSIFY FURTHER
THROUGH LATE AFTERNOON AS 80KT MID LEVEL JET SPREADS ACROSS THE
DRYLINE AND LOW LEVEL JET INTENSIFIES TO 50KT ACROSS THE OZARKS. A
SECONDARY AREA OF POSSIBLY LONG-TRACK AND FAST MOVING TORNADOES...IN
ADDITION TO VERY LARGE HAIL AND HIGH WINDS....COULD DEVELOP AHEAD OF
THE DRYLINE THROUGH THE EVENING.

PARTS OF BOTH NEB/IA AND THE ERN KS/OK AND WRN MO/AR AREAS MAY BE
UPGRADED TO HIGH RISK IN LATER OUTLOOKS IF MODEL GUIDANCE OVER THE
NEXT DAY CONTINUES TO SUGGEST A STRONG POTENTIAL FOR THE DEVELOPMENT
OF DANGEROUS WEATHER IN THESE AREAS.

....EAST FROM THE MS RIVER TO IL/IND/OH...
WHILE THE PRIMARY CYCLONE UNDERGOES OCCLUSION OVER THE PLAINS
THROUGH LATE IN THE DAY 2 PERIOD...INTENSE MID LEVEL WIND MAX WILL
SPREAD EAST ACROSS THE MIDWEST THROUGH LATE THURSDAY NIGHT. MODELS
SUGGEST A FRONTAL WAVE...POSSIBLY CONVECTIVELY INDUCED....MAY
DEVELOP RAPIDLY EWD ALONG THE WARM FRONT...FROM ERN IA/MO TO IND
THROUGH LATE EVENING. DESPITE WEAKENING INSTABILITY WITH EWD
EXTENT...A PLUME OF STRONGER INSTABILITY MAY STREAM INTO THESE AREAS
FROM THE LOWER OH VALLEY. THREAT FOR DAMAGING WINDS AND POSSIBLY
SOME LATE NIGHT TORNADOES MAY ACCOMPANY AN MCS OR TWO EVOLVING OUT
OF THE PLAINS CONVECTION AND SUPPORTED/MAINTAINED BY  LARGER SCALE
DYNAMICS.

..CARBIN.. 04/05/2006