[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 211157
SWODY1
SPC AC 211156

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0656 AM CDT WED JUN 21 2006

VALID 211300Z - 221200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING FROM
SOUTHEAST IA...ACROSS NORTHERN IL...NORTHERN IND...SOUTHERN LOWER
MI...AND NORTHWEST OH...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL ROCKIES INTO
THE GREAT LAKES REGION...

FAST ZONAL FLOW PATTERN IS PRESENT TODAY ACROSS THE NORTHERN HALF OF
THE NATION...WITH SEVERAL EMBEDDED SHORTWAVE TROUGHS.  THIS WILL
LIKELY LEAD TO AN AXIS OF ACTIVE SEVERE WEATHER TODAY FROM THE
CENTRAL ROCKIES...ACROSS THE CENTRAL PLAINS...AND INTO THE GREAT
LAKES REGION.

...UPPER MS VALLEY AND GREAT LAKES...
LINE OF INTENSE THUNDERSTORMS IS AFFECTING PARTS OF EASTERN
IA/NORTHERN IL/SOUTHERN WI THIS MORNING.  THESE STORMS ARE IN REGION
OF STRONG LOW LEVEL WARM ADVECTION AND FAVORABLE VERTICAL SHEAR FOR
SEVERE STORMS. CELLS ALONG THIS AXIS MAY POSE A THREAT FOR HAIL AND
DAMAGING WINDS THROUGH THE MORNING HOURS AS THEY SPREAD EASTWARD
INTO LOWER MI.

MEANWHILE...COMPACT VORT MAX IS SHOWN ON WATER VAPOR IMAGERY AND
MODEL GUIDANCE OVER EASTERN NEB.  THIS FEATURE IS FORECAST TO TRACK
EASTWARD ALONG THE MO/IA BORDER AND INTO NORTHERN IL BY EARLY
AFTERNOON.  FORCING FOR UPWARD VERTICAL MOTION AHEAD OF SYSTEM WILL
LIKELY INITIATE FURTHER CONVECTION BY LATE MORNING ALONG OUTFLOW
BOUNDARY FROM MORNING STORMS.  THESE STORMS ARE EXPECTED TO RAPIDLY
BECOME SEVERE WITH A RISK OF SUPERCELLS...LARGE HAIL...AND DAMAGING
WINDS. DEGREE OF INSTABILITY...FAVORABLE KINEMATIC FIELDS...AND
APPROACHING TROUGH SUGGEST THAT ENVIRONMENT WILL BE FAVORABLE FOR
UPSCALE ORGANIZATION OF SYSTEM DURING THE AFTERNOON AS STORMS TRACK
ACROSS NORTHERN IL/SOUTHERN LOWER MI/NORTHERN IND/NORTHWEST OH. 
WIDESPREAD AND SIGNIFICANT DAMAGING WINDS WILL BE POSSIBLE ALONG
THIS AXIS...ALONG WITH LARGE HAIL AND ISOLATED TORNADOES.  IF
ACTIVITY CAN BECOME SUFFICIENTLY ORGANIZED...DERECHO MAY PERSIST
INTO WESTERN NY OVERNIGHT BEFORE WEAKENING.

...CENTRAL HIGH PLAINS...
EASTERLY LOW LEVEL WINDS ARE PRESENT AGAIN THIS MORNING OVER THE
PLAINS OF CO.  THIS REGIME IS EXPECTED TO PERSIST THROUGH THE
DAY...BENEATH RELATIVELY FAST WESTERLY MID LEVEL FLOW. PRESENT
INDICATIONS ARE THAT STORMS WILL FORM BY MID AFTERNOON OVER THE
MOUNTAINS AND FOOTHILLS...AND SPREAD EASTWARD INTO THE ADJACENT
PLAINS BY EVENING.  FORECAST SOUNDINGS ACROSS EASTERN CO AND
NORTHEAST NM SHOW VERY FAVORABLE THERMODYNAMIC AND KINEMATIC FIELDS
FOR SUPERCELLS.  LARGE HAIL AND DAMAGING WINDS WILL BE POSSIBLE
ACROSS THIS REGION THROUGH THE EVENING AS STORMS SPREAD INTO
SOUTHWESTERN NEB...WESTERN KS...AND THE TX/OK PANHANDLES. 
FAST-MOVING MCS DEVELOPMENT IS POSSIBLE IN THIS REGION OVERNIGHT AS
STORMS MOVE THROUGH WESTERN/CENTRAL KS.

..HART/CROSBIE.. 06/21/2006