[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 122017
SWODY1
SPC AC 122016

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0216 PM CST SAT NOV 12 2005

VALID 122000Z - 131200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 W
FLV 20 ESE YKN 20 NNW BKX 20 NNE RWF 35 SE MSP 30 WNW LSE 45 NNW DBQ
25 NW MLI 25 SSE BRL 45 WSW FAM 30 SSE BVX 25 ENE ELD 50 WNW POE UTS
20 SSE ACT 10 W DAL 35 NE TUL 25 ENE CNU 20 W FLV.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 E CRP 25 NE COT 25
NNW HDO 15 WSW FTW 20 E OKC 30 ENE CNK 10 WSW OLU 35 E ONL 20 ENE
VTN 35 NNW VTN 25 NNE PIR 15 N INL ...CONT... 35 NW CLE 45 ESE BWG
40 E TUP 30 N HEZ 45 NW LFT 55 SW 7R4.

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE FAR SERN SD/SRN MN SWD
TO NERN TX...

...MIDDLE/LOWER MO VALLEY...
EARLY AFTERNOON SURFACE ANALYSES INDICATED A DEEP SURFACE LOW OVER
FAR NERN NEB WITH THE TRAILING DRY LINE AND COLD FRONT MOVING
QUICKLY EWD ACROSS ERN NEB...CENTRAL/ERN KS AND OK.  SURFACE LOW IS
PROGGED TO DEEPEN FURTHER AS STRONG HEIGHT FALLS /180-200 METERS/
SPREAD ACROSS THE UPPER MS VALLEY...WITH THE LOW REACHING CENTRAL MN
THIS EVENING AND WRN LAKE SUPERIOR BY 12Z SUNDAY.

STRONG SLY LOW LEVEL FLOW AHEAD OF THESE BOUNDARIES HAD CONTINUED TO
ADVECT A NARROW PLUME OF MOISTURE NWD WITH SURFACE DEWPOINTS INTO
THE MID 50S FROM SERN SD TO CENTRAL IA...AND LOWER 60S ALONG THE
KS/MO BORDER REGION.  GIVEN TRACK OF SURFACE LOW...WARM SECTOR IS
EXPECTED TO DEVELOP NWD INTO SRN MN AIDING IN THE THREAT FOR SURFACE
BASED STORMS.  STRONG SURFACE HEATING WITHIN THE MID LEVEL DRY SLOT
AND ALONG WRN EDGE OF LOW LEVEL MOISTURE PLUME ACROSS ERN NEB/KS
WILL CONTINUE TO RESULT IN MLCAPE VALUES AROUND 1000 J/KG... AND UP
TO 1500 J/KG OVER NRN TX.  18Z SOUNDINGS AT TOP/OMA BOTH INDICATED A
LOW LEVEL CAP. 19Z OBJECTIVE ANALYSIS SHOWED THE CAP IS CONTINUING
TO WEAKEN AS STRONG LARGE SCALE FORCING/PV ADVECTION SPREADS RAPIDLY
ENEWD AHEAD OF THE CENTRAL PLAINS TROUGH AND WITHIN THE EXIT REGION
OF A 70-90 KT WNWLY MID LEVEL JET NOSING INTO THE CENTRAL PLAINS. 
FURTHER WEAKENING OF THIS CAP COMBINED WITH THE NARROW AXIS OF
MODERATE INSTABILITY AND STRONG DEEP LAYER SHEAR SUGGEST
THUNDERSTORM INITIATION WILL BE ALONG THE DRY LINE IN FAR ERN
NEB/WRN IA/SERN SD AND THEN SWD INTO ERN KS BY 20-21Z. STORM MODE
IS EXPECTED TO BE LINEAR GIVEN DEEP UNI-DIRECTIONAL WIND PROFILES
AND SHEAR VECTORS ORIENTED NEARLY PARALLEL TO THE DRY LINE/COLD
FRONT. HOWEVER...EMBEDDED SUPERCELLS WITH AN ATTENDANT TORNADO
THREAT WILL ALSO BE LIKELY GIVEN LOW LEVEL HODOGRAPH CURVATURE AS
INDICATED ON THE 18Z TOP/OMA SOUNDINGS.

ONCE STORMS INITIATE...THE ACTIVITY IS EXPECTED TO SPREAD FAIRLY
QUICKLY ENEWD ACROSS SRN MN/IA AND INTO MO.  THE LOSS OF INSTABILITY
THIS EVENING SUGGESTS OVERALL SEVERE THREAT WILL GRADUALLY DECREASE
WITH EWD EXTENT AS COLD FRONT/FORCING WITH UPPER TROUGH MOVE AWAY
FROM STRONGER LOW LEVEL MOISTURE.  THE DAMAGING WIND THREAT IS
EXPECTED TO BE THE GREATER THREAT THIS EVENING GIVEN SPEED OF SYSTEM
AND CONTINUATION OF STRONG WIND FIELDS/DEEP LAYER SHEAR FOR LOW
TOPPED STORMS. THIS THREAT MAY REACH INTO PARTS OF WI/IL.

...ERN OK/WRN AR/NORTH CENTRAL AND NERN TX/NWRN LA...
VIS IMAGERY SHOWED CU FIELD DEVELOPING SWD ALONG THE DRY LINE INTO
NORTH CENTRAL-NERN OK EARLY THIS AFTERNOON.  AIR MASS ALONG/E OF
THIS BOUNDARY HAS BECOME MODERATELY UNSTABLE WITH INCREASING DEEP
LAYER SHEAR TO SUPPORT ORGANIZED STORMS.  FOR ADDITIONAL INFORMATION
ABOUT THE NEAR TERM SEVERE THREAT...PLEASE REFER TO SPC MESOSCALE
DISCUSSION /SPCSWOMCD/ 2404.

LATER THIS EVENING...INSTABILITY IS EXPECTED TO DIMINISH SOMEWHAT
WITH OVERALL SEVERE THREAT TENDING TO DECREASE.  HOWEVER...
SUFFICIENT INSTABILITY/SHEAR VALUES SHOULD REMAIN ACROSS PARTS OF
NERN TX TO THE ARKLATEX REGION FOR A FEW SEVERE STORMS INTO THE
OVERNIGHT PERIOD AS THE COLD FRONT/DRY LINE MOVE SEWD.

..PETERS.. 11/12/2005

...NOTICE...
THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE
SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1...
WUUS02 PTSDY2...WUUS03 PTSDY3.  THE INCLUSION OF POINTS
IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005
CONVECTIVE SEASON.  A PUBLIC NOTIFICATION STATEMENT (PNS)
WILL PROVIDE DETAILS ON THE TRANSITION.