[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 171623
SWODY1
SPC AC 171621

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CDT SAT JUN 17 2006

VALID 171630Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE CENTRAL AND SOUTHERN
PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS UPPER MIDWEST AND WESTERN GREAT
LAKES REGION...

UPPER LOW LOCATED SWRN NEB/KS BORDER WITH TROUGH AND COLDER AIR
ALOFT EXTENDING SSWWD INTO SWRN TX.  LOW OPENING UP AS TROUGH MOVES
EWD ACROSS CENTRAL/SRN PLAINS THIS AFTERNOON AND TONIGHT. FURTHER N
S/WV TROUGH IN FASTER WESTERLIES ALONG CANADIAN BORDER MOVES EWD
FROM CURRENT LOCATION MT/ND AREA ACROSS UPPER MS VALLEY TONIGHT.

EXTENSIVE OVERNIGHT CONVECTION ACROSS MUCH OF PLAINS HAS SLOWED
HEATING OF THE STILL VERY MOIST AND POTENTIALLY QUITE UNSTABLE
AIRMASS.  ONGOING MCS ERN TX MOVING INTO VERY MOIST/UNSTABLE AIR
MASS IN PLACE LOWER MS VALLEY.

...CENTRAL/SRN PLAINS...
AFTERNOON SURFACE HEATING COUPLED WITH COOLING ALOFT AS UPPER TROUGH
MOVES EWD EXPECTED TO RAPIDLY DESTABILIZE AIRMASS FROM SRN KS SWD
INTO NCENTRAL/NWRN TX. WHILE DEEP LAYER SHEAR WILL WEAKEN WITH
APPROACH OF THE UPPER TROUGH...THE AIR MASS BECOMES VERY UNSTABLE ON
THE WRN EDGE OF DEEPER MOISTURE WRN OK INTO NWRN TX.  WITH MLCAPES
AOA 2500 J/KG...STEEP LAPSE RATES IN EXCESS OF 8 C/KM AND 30 KT OF
DEEP LAYER SHEAR...SEVERE THUNDERSTORMS INCLUDING SUPERCELLS SHOULD
DEVELOP BY MID AFTERNOON. GREATEST THREAT WILL BE VERY LARGE
HAIL...BUT WITH DCAPES IN EXCESS OF 1500 J/KG DAMAGING DOWNBURSTS
ALSO EXPECTED. ISOLATED TORNADOES ARE POSSIBLE WITH ANY SUPERCELL
UNTIL LATER THIS EVENING...HOWEVER MARGINAL SHEAR SUGGESTS ANY
OCCURRENCE WILL BE SHORT LIVED.

SEVERE THUNDERSTORMS ARE LIKELY TO CONTINUE WELL AFTER
DARK...PARTICULARLY CENTRAL TX WHERE DEEP LAYER SHEAR AND
INSTABILITY WILL BE THE GREATEST.

...ERN TX/LOWER MS VALLEY...
ONGOING FORWARD PROPAGATING MCS ACROSS ERN TX EXPECTED TO INTENSIFY
BY EARLY THIS AFTERNOON.  12Z SOUNDINGS SHOW VERY MOIST AND UNSTABLE
AIR MASS IN ADVANCE OF MCS WITH CONSIDERABLE DRY AIR AT MID/UPPER
LEVELS.  WITH HEATING MLCAPES ARE ALREADY ABOVE 2500 J/KG...THUS
WIND DAMAGE POTENTIAL SHOULD RAMP UP EARLY THIS AFTERNOON AS MCS
MOVES INTO LA.

... MN/WI/MI...
A MOIST/UNSTABLE AIR MASS REMAINS SERN MN/WI INTO UPPER MI. ONGOING
HEATING WILL QUICKLY WEAKEN CIN AND ALLOW THUNDERSTORMS TO DEVELOP
BY MID AFTERNOON EAST OF THE THICK CLOUD COVER OVER WRN AND NRN MN. 
WITH MLCAPES TO 2000 J/KG...30-40 KT OF PRIMARILY UNIDIRECTIONAL
SHEAR...MULTICELLULAR SEVERE STORMS ARE LIKELY WITH DOWNBURST WIND
AND LARGE HAIL.  STORMS SHOULD PROPAGATE E/NEWD ACROSS WI/UPR MI
PRIOR TO WEAKENING LATER THIS EVENING.

..HALES/GRAMS.. 06/17/2006