[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 201618
SWODY1
SPC AC 201616

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1116 AM CDT SAT MAY 20 2006

VALID 201630Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE OZARKS TO THE CAROLINA
COAST...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE NRN HIGH
PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PART OF THE CENTRAL GREAT
LAKES...

...MID SOUTH ACROSS SRN APPALACHIANS INTO THE COASTAL CAROLINAS...
QUASI-STATIONARY FRONT EXTENDING FROM FAR SRN MO ESEWD INTO MIDDLE
TN AND EWD INTO THE PIEDMONT OF NC/VA THIS MORNING WILL PROVIDE
PRIMARY FOCUS FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON/EVENING. 
SURFACE OUTFLOW BOUNDARY ACROSS SERN SC INTO NRN GA MAY PROVIDE
ADDITIONAL FOCUS.  THOUGH MID/UPPER LEVEL PATTERN REMAINS MORE LIKE
MID-SUMMER...WARM SECTOR MOISTURE IS NOT OVERLY IMPRESSIVE WITH
SURFACE DEW POINTS IN THE LOWER TO MID 60S. LIMITED LARGE SCALE
ASCENT AND RISING HEIGHTS AT H5 INDICATE DEVELOPMENT WILL BE DRIVEN
BY HEATING TODAY.  LACK OF LARGE SCALE FOCUS AND LIMITED LLJ
DEVELOPMENT SUGGEST THUNDERSTORMS COULD INITIATE ANYWHERE ALONG THE
FRONT/OUTFLOW BOUNDARY THIS AFTERNOON...WHERE POCKETS OF WEAK CINH
DEVELOP.  HOWEVER...SATELLITE IMAGERY AND RECENT CONVECTIVE TRENDS
MAY SUPPORT WEAK IMPULSE NOW MOVING ESEWD ACROSS MIDDLE TN WHICH
COULD FOCUS INITIAL DEVELOPMENT ACROSS THE SRN APPALACHIANS EARLY
THIS AFTERNOON.

MODELS ARE AGAIN FAR TOO MOIST NEAR THE SURFACE AND APPEAR TO BE
OVER FORECASTING EXPECTED SBCAPE/MLCAPE TODAY. HOWEVER...MLCAPE MAY
STILL APPROACH 2000 J/KG ACROSS THE UPPER SOUTH /SOUTH OF SURFACE
BOUNDARY/ WHERE AFTERNOON TEMPS APPROACH/EXCEED 90F.  MODEST WLY
FLOW ALOFT WILL ALSO SUSTAIN 35-45 KT EFFECTIVE SHEAR...SUPPORTIVE
OF SUPERCELLS AND ORGANIZATION INTO SMALL LINES/BOW ECHOES MOVING
SEWD LATER TODAY AND THIS EVENING.  STEEP SUB-CLOUD LAPSE RATES AND
NEAR UNIDIRECTIONAL FLOW ALOFT WILL SUPPORT PRIMARY THREAT OF
DAMAGING WINDS.  THOUGH PRESENCE OF SURFACE BOUNDARY MAY ENHANCE LOW
LEVEL SHEAR ENOUGH FOR A TORNADO OR TWO...WHILE MLCAPE AND STEEP
LAPSE RATES ALSO SUPPORT LARGE HAIL.

...SRN HIGH PLAINS INTO THE OZARKS...
BOUNDARY WILL REMAIN STALLED NEAR THE MO/AR BORDER INTO FAR SRN
KS/NWRN OK TODAY...AS WEAK LOW CENTER PERSISTS ALONG TRIPLE POINT OF
FRONT AND DRY LINE NEAR THE TX/OK PANHANDLES.  STRONG HEATING AND
INFLUX OF ASCENT AHEAD OF WEAK SHORTWAVE TROUGH NOW SHIFTING SEWD
ACROSS NEB SHOULD SUPPORT A FEW THUNDERSTORMS NEAR THIS BOUNDARY
LATER TODAY.  WRN END OF FRONT ACROSS NRN EXTENT OF SRN PLAINS
REMAINS UNDER MID LEVEL RIDGE AND ASSOCIATED WEAK MID LEVEL FLOW...
SUGGESTING STORMS ACROSS THIS AREA WILL BE MORE PULSE IN NATURE WITH
BRIEF DAMAGING WINDS/HAIL.  STORMS WHICH CAN DEVELOP AHEAD OF WEAK
MID LEVEL SYSTEM INTO SRN MO/FAR SERN KS WILL HAVE MODEST SHEAR AND
LIKELY ORGANIZE INTO MULTICELL CLUSTERS/LINES WITH THREATS OF LARGE
HAIL/DAMAGING WINDS LATE TODAY AND THIS EVENING.

...MT INTO FAR NERN WY...
WELL DEFINED SHORTWAVE TROUGH NOW LIFTING ACROSS THE NRN
INTERMOUNTAIN REGION WILL INCREASE MOIST CONVECTION ACROSS THE NRN
ROCKIES TODAY...WHERE MODEST LAPSE RATES AND SURFACE DEW POINTS
AROUND 50F WILL SUPPORT MARGINAL TO MODERATE INSTABILITY TODAY. 
ASSOCIATED 40-50 KT SWLY MID LEVEL SPEED MAX WILL ALSO INCREASE DEEP
LAYER SHEAR ACROSS MUCH OF WRN/CENTRAL MT AND NRN WY THIS
AFTERNOON...WHERE FORECAST SOUNDINGS YIELD SUFFICIENT DEEP LAYER
SHEAR FOR A FEW SUPERCELLS AND ORGANIZED CLUSTERS/LINES.  SURFACE
COLD FRONT NOW MOVING SWD INTO THE NRN PLAINS HAS PUSHED WWD INTO
ERN MT THIS MORNING AND MAY LIMIT EWD EXTENT OF ANY SEVERE THREAT
LATER THIS EVENING.  HOWEVER...ACTIVITY INCREASING ACROSS WRN MT
INTO NRN WY WILL LIKELY BECOME SEVERE OVER LOWER ELEVATIONS GIVEN
STRONG HEATING AND SHIFT ENEWD THROUGH THE EVENING.

...CENTRAL GREAT LAKES...
SEVERE THREAT APPEARS CONDITIONAL ACROSS THIS REGION AS PRE-FRONTAL
BOUNDARY LAYER MOISTURE AND MID LEVEL LAPSE RATES REMAIN WEAK THIS
MORNING.  HOWEVER...STRONG COLD FRONT ASSOCIATED WITH DEEPENING
SHORTWAVE TROUGH NOW SHIFTING SSEWD INTO THE NRN GREAT LAKES WILL
SUPPORT STRONG LARGE SCALE ASCENT ACROSS THE CENTRAL GREAT LAKES
TODAY. MODELS CONTINUE TO INCREASE SURFACE DEW POINTS INTO THE
LOWER 50S IMMEDIATELY AHEAD OF APPROACHING COLD FRONT. 
HOWEVER...LATEST OBSERVATIONAL DATA SUGGESTS THIS MAY BE OVERDONE
AND CASTS SOME DOUBT AS TO WHETHER OR NOT SUFFICIENT INSTABILITY
WILL DEVELOP FOR SURFACE-BASED CONVECTION ALONG THE FRONT.  SHOULD
THUNDERSTORMS FORM WITHIN NARROW AXIS OF MARGINAL INSTABILITY
TODAY...VERY STRONG WINDS ALOFT AND INCREASING LARGE SCALE ASCENT
COULD SUPPORT DAMAGING WINDS AS STEEP SUB-CLOUD LAPSE RATES DEVELOP
FROM SURFACE TEMPERATURES APPROACHING 70F.

..EVANS/GUYER.. 05/20/2006