[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 060102
SWODY1
SPC AC 060100

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT WED APR 05 2006

VALID 060100Z - 061200Z

...THERE IS A SLGT RISK OF SVR TSTMS TONIGHT FROM PARTS OF THE NRN
HIGH PLAINS INTO THE MID/LOWER MISSOURI VALLEY....

CLOSED LOW EMBEDDED WITHIN LARGE-SCALE WESTERN U.S. UPPER TROUGH
CURRENTLY APPEARS CENTERED OVER THE NORTH CENTRAL GREAT BASIN...
WITH INITIAL IMPULSE ROTATING AROUND ITS SOUTHERN/EASTERN
PERIPHERY...INTO THE NORTH CENTRAL ROCKIES.  FORCING WITH THIS
FEATURE HAS CONTRIBUTED TO THE DEVELOPMENT OF A DEEP SURFACE
LOW...WHICH HAS SHIFTED ACROSS NORTH CENTRAL WYOMING INTO SOUTH
CENTRAL/SOUTHEASTERN MONTANA.  

HOWEVER...IT STILL APPEARS THAT PRIMARY SURFACE LOW WILL EVENTUALLY
FORM ACROSS NORTHEAST COLORADO INTO WESTERN NEBRASKA OVERNIGHT. 
THIS IS PROGGED TO OCCUR AS A MORE SIGNIFICANT IMPULSE ACCELERATES
EASTWARD OUT OF THE LOWER COLORADO VALLEY.  STRONG MID-LEVEL COOLING
WILL ACCOMPANY THIS FEATURE INTO THE SOUTH CENTRAL ROCKIES LATE
TONIGHT...AND MID-LEVEL CLOSED LOW WILL BEGIN TO REDEVELOP
SOUTHEASTWARD INTO THE CENTRAL ROCKIES/HIGH PLAINS BY 12Z
THURSDAY...OR SHORTLY THEREAFTER.

...SOUTHEAST MONTANA...
DESPITE VERY LIMITED LOW-LEVEL MOISTURE...STEEP LOW/MID-LEVEL LAPSE
RATES HAVE DEVELOPED IN WARM SECTOR OF DEEP SURFACE LOW.  CAPE MAY
BE WEAK...BUT THERMODYNAMIC PROFILES WITH A DEEPLY MIXED BOUNDARY
LAYER WILL BE SUPPORTIVE OF PRIMARILY DAMAGING WIND GUSTS THROUGH
EARLY EVENING. SHEAR PROFILES ARE SUFFICIENT FOR UPDRAFT
ROTATION...AND AN ISOLATED SUPERCELL MAY STILL DEVELOP BEFORE
NIGHTFALL BETWEEN BILLINGS AND MILES CITY...WHICH WOULD ENHANCE RISK
FOR STRONG WIND GUSTS/HAIL...PERHAPS A BRIEF TORNADO.

...MID/LOWER MISSOURI VALLEY...
SCATTERED VIGOROUS CONVECTIVE DEVELOPMENT IS ALREADY UNDERWAY ACROSS
PARTS OF THE LOWER MISSOURI VALLEY...WHERE SOUTHERLY LOW-LEVEL JET
IS ENHANCING WARM ADVECTION...NORTH OF CAPPING MID-LEVEL RIDGE. 
ACTIVITY IS BASED IN ELEVATED MOIST LAYER WITH MOST UNSTABLE CAPE
INCREASING AS HIGH AS 1500 J/KG...WHICH WILL SUPPORT AT LEAST
MARGINALLY SEVERE HAIL IN FAVORABLY SHEARED ENVIRONMENT.  COVERAGE
OF STORMS SHOULD CONTINUE TO INCREASE OVERNIGHT.

...WESTERN SOUTH DAKOTA/NORTHERN NEBRASKA...
EXIT REGION OF STRONG MID-LEVEL JET MAY BEGIN TO OVERSPREAD WARM
FRONTAL ZONE TOWARD 09-12Z.  THIS SHOULD WEAKEN INHIBITION ALONG
BOUNDARY...WHICH WILL BECOME FOCUS FOR THUNDERSTORM ACTIVITY.  CAPE
FOR MOIST PARCELS BASED ABOVE FRONTAL INVERSION IS EXPECTED UP TO
AROUND 1500 J/KG...WHICH WILL CONTRIBUTE TO RISK FOR SEVERE
STORMS...MAINLY WITH LARGE HAIL.

..KERR.. 04/06/2006