[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 220612
SWODY2
SPC AC 220611

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0111 AM CDT SAT APR 22 2006

VALID 231200Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS CENTRAL PLAINS TO LOWER
OH/TN VALLEYS...

...SYNOPSIS...
UPPER TROUGH/CLOSED LOW MOVING INLAND OVER CA AT THIS TIME PER WATER
VAPOR IMAGERY WILL CONTINUE TO UNDERGO FURTHER WEAKENING ON SUNDAY
AS IT MOVES SLOWLY NEWD ACROSS THE GREAT BASIN AND NRN INTERMOUNTAIN
REGION.  MEANWHILE...SRN PART OF TROUGH OVER CENTRAL CANADA WILL
MOVE INTO THE DAKOTAS/UPPER MS VALLEY...WITH DOWNSTREAM CLOSED LOW
MOVING SLOWLY NEWD ACROSS THE LOWER GREAT LAKES/CENTRAL
APPALACHIANS.

IN THE LOW-LEVELS...WEAK SURFACE LOW ASSOCIATED WITH GREAT LAKES
CLOSED LOW WILL TRACK SLOWLY NEWD...WITH TRAILING SURFACE FRONT
MOVING EWD ACROSS NY/PA/CENTRAL APPALACHIANS ON SUNDAY.  THE
REMAINING PORTION OF THIS BOUNDARY EXTENDING FROM THE OH VALLEY WWD
THROUGH CENTRAL MO TO CENTRAL KS...AND THEN WNWWD INTO HIGH PLAINS
OF NERN CO/SERN WY EXPECTED TO REMAIN QUASI-STATIONARY THROUGH THE
PERIOD.  DRY LINE IS EXPECTED TO MIX EWD AND SHOULD EXTEND FROM SWRN
KS INTO FAR WRN OK TO PARTS OF WRN TX. 

...CENTRAL PLAINS INTO MO...
ELEVATED THUNDERSTORMS SHOULD BE ONGOING AT THE START OF THE PERIOD
FROM ERN KS ESEWD INTO CENTRAL/SRN MO TO LOWER OH VALLEY WITHIN WAA
REGIME ALONG NOSE OF STRONG W/SWLY LLJ.  THIS ACTIVITY SHOULD
GRADUALLY WEAKEN SUNDAY MORNING AS STRENGTH OF LLJ DECREASES...
THOUGH WAA N OF SURFACE BOUNDARY MAY REMAIN SUFFICIENT FOR ELEVATED
THUNDERSTORMS SUNDAY MORNING/AFTERNOON FROM PARTS OF NRN HIGH PLAINS
SEWD INTO NEB. WEAK INSTABILITY WITH THIS LATTER ACTIVITY SHOULD
LIMIT THE SEVERE THREAT.

MEANWHILE...MOISTURE RETURN WILL CONTINUE ACROSS THE SRN/CENTRAL
PLAINS WITH SURFACE DEWPOINTS IN THE LOWER-MID 60S ALONG/S OF
SURFACE BOUNDARY FROM FAR SWRN NEB SEWD TO CENTRAL MO AND WRN KY/TN.
ELEVATED MIXED LAYER /STEEP MID-LEVEL LAPSE RATES 7.5+ C/KM/
SPREADING EWD ACROSS MUCH OF THE CENTRAL/SRN PLAINS TO LOWER TN/MS
VALLEYS DAY 1 WILL REMAIN IN PLACE DAY 2.  IN ADDITION TO
CONTRIBUTING TO A MODERATE-VERY UNSTABLE WARM SECTOR...THIS EML
SHOULD EFFECTIVELY CAP THE WARM SECTOR INTO THE MID-LATE
AFTERNOON...ESPECIALLY SWD ALONG DRY LINE.

WEAK MID-LEVEL IMPULSES EMANATING FROM WRN STATES TROUGH ARE
EXPECTED TO MOVE EWD ACROSS THE PLAINS TOWARD THE MID MS VALLEY. 
LARGE SCALE ASCENT WITH THESE FEATURES AND HEIGHT FALLS ACROSS THE
NRN/CENTRAL PLAINS IN ADVANCE OF CANADIAN TROUGH ARE EXPECTED TO
SUPPORT THUNDERSTORM DEVELOPMENT BY MID-LATE AFTERNOON ALONG THE
SURFACE BOUNDARY FROM SERN WY INTO CENTRAL KS. INCREASING WLY
MID-LEVEL WINDS ATOP STRENGTHENING CENTRAL/SRN PLAINS SLY LLJ BY
LATE SUNDAY AFTERNOON WILL RESULT IN STRONG DEEP LAYER SHEAR
SUPPORTING SUPERCELLS CAPABLE OF PRODUCING TORNADOES...LARGE
HAIL...AND DAMAGING WINDS.  FURTHER STRENGTHENING AND EVENTUAL
VEERING OF LLJ EXPECTED TO RESULT IN UPSCALE GROWTH OF
AFTERNOON/EVENING STORMS INTO AN MCS MOVING EWD INTO ERN KS/MO
SUNDAY NIGHT WITH CONTINUED THREAT FOR DAMAGING WINDS/HAIL.

...OH/TN VALLEYS...
DESPITE RATHER WEAK CONVERGENCE ALONG THE SURFACE BOUNDARY...THE
COMBINATION OF INCREASING MOISTURE/INSTABILITY AND STRONG DEEP LAYER
SHEAR GIVEN NWLY MID-LEVEL FLOW ATOP WLY LLJ EXPECTED TO SUPPORT
WIDELY SCATTERED STRONG TO SEVERE STORMS.  PRIMARY THREATS SHOULD BE
DAMAGING WINDS AND HAIL WITH THE STRONGEST ACTIVITY.  THESE STORMS
ARE EXPECTED TO WEAKEN SUNDAY EVENING AS THE BOUNDARY  LAYER
STABILIZES WITH THE LOSS OF DAYTIME HEATING.

...PARTS OF NY/PA/WV/VA/MD...
COLD MID-LEVEL TEMPERATURES -20 TO -26 C AT 500 MB WITH THE CLOSED
LOW WILL STEEPEN LAPSE RATES CONTRIBUTING TO WEAK INSTABILITY IN
ADVANCE OF THE SURFACE TROUGH MOVING EWD ACROSS THIS REGION SUNDAY. 
LARGE SCALE ASCENT WITHIN EXIT REGION OF 60-70 KT JET ROUNDING BASE
OF UPPER SYSTEM WILL SUPPORT THUNDERSTORM DEVELOPMENT ALONG EXTENT
OF SURFACE BOUNDARY.  STRONG DEEP LAYER SHEAR SUGGESTS STORMS WILL
BE ORGANIZED...BUT WEAK INSTABILITY SHOULD LIMIT SEVERE COVERAGE.

..PETERS.. 04/22/2006