[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 270606
SWODY2
SPC AC 270605

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0105 AM CDT SAT MAY 27 2006

VALID 281200Z - 291200Z

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

...SYNOPSIS...
MODELS TEND TO AGREE THAT THE SHORT WAVE TROUGH EXPECTED TO MOVE ESE
INTO THE GREAT BASIN DURING DAY 1 PERIOD WILL TRACK NE TOWARD THE
NRN HIGH PLAINS/SRN CANADA ON SUNDAY.  HOWEVER...SOME DISCREPANCIES
EXIST WITH THE AMOUNT OF HEIGHT FALLS /GFS AND ECMWF WEAKER/ WITH
THIS SYSTEM AS IT APPROACHES THE NRN HIGH PLAINS/SRN CANADA LATE DAY
2. NONETHELESS...MID LEVEL HEIGHTS ARE EXPECTED TO TIGHTEN WITH
RESULTANT STRENGTHENING OF SWLY WINDS AT THIS SAME LEVEL TO AT LEAST
70 KT ACROSS THE NRN PLAINS.  IN THE LOW LEVELS...SURFACE TROUGH IS
EXPECTED TO MOVE SLOWLY EWD ACROSS THE ERN DAKOTAS/CENTRAL NEB...
WHILE A DRY LINE EXTENDING SWD MIXES EWD REACHING CENTRAL KS TO
ALONG THE WRN OK/TX BORDER TO THE TX BIG BEND REGION BY SUNDAY
AFTERNOON.

FARTHER EAST...UPPER RIDGE WILL REMAIN IN PLACE OVER THE ERN U.S.
WITH GENERALLY WEAK DEEP LAYER WIND FIELDS.

...NRN PLAINS...
AIR MASS ALONG/E OF THE SURFACE TROUGH IS EXPECTED TO REMAIN MOIST
AND VERY UNSTABLE WITH MLCAPE 2000-3000 J/KG...BUT STRONG ELEVATED
MIXED LAYER WILL LIKELY MAINTAIN THE CAP OVER THE NRN PLAINS THROUGH
THE AFTERNOON...LIMITING THE POTENTIAL FOR SURFACE-BASED STORMS.  IF
STORMS CAN DEVELOP SUNDAY AFTERNOON ALONG THE SURFACE BOUNDARY IN
ND/SD...THEN STRONG DEEP LAYER SHEAR WOULD SUPPORT ORGANIZED STORMS/
SUPERCELLS.  GREATER LIKELIHOOD FOR THUNDERSTORMS/ATTENDANT SEVERE
THREAT SHOULD BE SUNDAY EVENING AS ASCENT INCREASES AHEAD OF
APPROACHING GREAT BASIN TROUGH AND ALONG NOSE OF STRENGTHENING
CENTRAL PLAINS LLJ.  ACTIVITY WILL LIKELY BE LOCATED NORTH OF THE
SURFACE BOUNDARY WITH HAIL BEING THE PRIMARY THREAT OVERNIGHT.

THUNDERSTORMS WILL ALSO BE POSSIBLE SUNDAY AFTERNOON ALONG THE
HIGHER TERRAIN OF ERN WY/NRN CO WITHIN UPSLOPE FLOW REGIME NORTH OF
SURFACE BOUNDARY.  INSTABILITY IS EXPECTED TO BE WEAK...THUS
PRECLUDING A GREATER SEVERE RISK.  HOWEVER...SOME OF THIS ACTIVITY
MAY SPREAD ENE AND GROW UPSCALE INTO A CLUSTER OF STORMS TRACKING
NEWD ACROSS NRN NEB/SD INTO ERN ND/WRN MN LATER SUNDAY NIGHT.

...SRN PLAINS...
AIR MASS WILL BE MODERATELY TO VERY UNSTABLE SWD ALONG/E OF THE DRY
LINE...BUT SHOULD REMAIN CAPPED UNTIL MID-LATE AFTERNOON.  POINT
FORECAST SOUNDINGS SUGGEST SURFACE HEATING SHOULD BECOME SUFFICIENT
BETWEEN 20-23Z TO ALLOW SURFACE PARCELS TO REACH THEIR LFC.  STEEP
LAPSE RATES...MLCAPE UP TO 2500 J/KG AND DEEP LAYER SHEAR 25-30 KT
SUGGEST POTENTIAL FOR ORGANIZED STORMS.  HOWEVER... GIVEN MODEL
UNCERTAINTY IN OVERALL STORM COVERAGE...THIS OUTLOOK WILL MAINTAIN
LOW SEVERE PROBABILITIES INTRODUCED ON THE PREVIOUS DAY 3 OUTLOOK.

...OH VALLEY SWD TO GULF COAST STATES...
THUNDERSTORMS WILL BE AGAIN POSSIBLE ALONG THE EXTENT OF THE SURFACE
BOUNDARY FROM THE WRN GREAT LAKES SSEWD THROUGH THE LOWER OH/TN
VALLEYS TO THE GULF COAST STATES SUNDAY AFTERNOON.  MODERATE TO VERY
STRONG INSTABILITY EXPECTED ACROSS THESE AREAS AND WEAK DEEP LAYER
SHEAR SUGGESTS THE POTENTIAL FOR PULSE-TYPE STORMS.  A FEW STORMS
MAY BECOME CAPABLE OF PRODUCING A STRONG WIND GUST AND/OR MARGINALLY
SEVERE HAIL...BUT WILL NOT INTRODUCE SEVERE PROBABILITIES AT THIS
TIME.

..PETERS.. 05/27/2006