[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 220601
SWODY1
SPC AC 220559

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT MON MAY 22 2006

VALID 221200Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE INTERIOR NW EWD ACROSS
MT THEN SEWD TO THE CENTRAL HIGH PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE TN VALLEY TO NRN-ERN
GA AND PARTS OF SRN SC...

...SYNOPSIS...
STRONG SHORT WAVE TROUGH...CURRENTLY LOCATED JUST W OF SRN CA PER
WATER VAPOR IMAGERY...IS EXPECTED TO EJECT NEWD AS A NEGATIVELY
TILTED TROUGH ACROSS THE SWRN STATES REACHING THE FOUR CORNERS
REGION BY 23/00Z...THEN INTO THE CENTRAL ROCKIES/HIGH PLAINS BY 12Z
TUESDAY.  ALTHOUGH THIS TROUGH SHOULD DE-AMPLIFY SOME AS IT TRACKS
NEWD INTO THE PLAINS UPPER RIDGE...60-90 METER 500 MB HEIGHT FALLS
WILL BE MAINTAINED ALONG ITS PATH.  THE EJECTION OF THIS TROUGH IS
IN RESPONSE TO UPSTREAM HEIGHT FALLS UNDERWAY 300-500 MILES W OF NRN
CA/ORE...AS THE NERN PACIFIC DEEP UPPER LOW SETTLES SWD PRIOR TO 12Z
TODAY.

IN THE EAST...LONG WAVE TROUGH WILL REMAIN OVER THIS REGION WITH SRN
PERIPHERY OF STRONGEST MID LEVEL FLOW EXTENDING FROM THE WRN GREAT
LAKES SEWD ACROSS THE CENTRAL APPALACHIANS TO MID ATLANTIC STATES/
CAROLINAS.  QUASI-STATIONARY SURFACE BOUNDARY SHOULD EXTEND FROM SC
COAST NWWD THROUGH TN VALLEY INTO NRN AR AND ALONG THE OK/KS BORDER
WHERE IT SHOULD BE MORE DIFFUSE.

...CENTRAL/NRN HIGH PLAINS...
SSELY LOW-LEVEL FLOW WILL ALLOW MOISTURE TO CONTINUE TO RETURN NNWWD
ACROSS THE CENTRAL/NRN PLAINS THIS FORECAST PERIOD.  WEAK HEIGHT
FALLS EXPECTED IN ADVANCE OF MAIN SWRN TROUGH AND POTENTIALLY
ASSOCIATED WITH A WEAK IMPULSE TRACKING NEWD ACROSS THIS REGION WILL
LIKELY AID IN THUNDERSTORMS THIS AFTERNOON FROM ERN CO TO ERN MT. 
THIS ACTIVITY WILL BE ALONG THE WRN EDGE OF THE DEEP MOISTURE WHERE
MIXING AND SURFACE HEATING SHOULD WEAKEN THE CAP BY MID-LATE
AFTERNOON.  DEEP LAYER SHEAR WILL INITIALLY NOT BE STRONG...BUT
EXPECTED TO INCREASE THIS EVENING/TONIGHT AS MID LEVEL WIND MAX WITH
STRONGER SHORT WAVE TROUGH MOVES INTO CO. THUS...DESPITE SOME
DECREASE IN INSTABILITY AFTER 00Z...STRONG ASCENT SPREADING NEWD
WITH APPROACH OF UPPER TROUGH/PACIFIC COLD FRONT SHOULD ALLOW SEVERE
THREAT TO PERSIST THIS EVENING/TONIGHT.

...INTERIOR NW INTO WRN MT...
DEEP UPPER LOW REMAINING OVER THE NERN PACIFIC WILL MAINTAIN
MODERATE SLY MID LEVEL FLOW ACROSS THIS REGION FOR MUCH OF THE
FORECAST PERIOD.  THE AMOUNT OF CLOUD COVER EXPECTED ACROSS THIS
REGION TODAY MAY LIMIT THE DEGREE OF SURFACE HEATING.  HOWEVER...
RESIDUAL LOW-LEVEL MOISTURE BENEATH STEEP MID LEVEL LAPSE RATES
SHOULD RESULT IN MLCAPE VALUES RANGING FROM 500-1000 J/KG...WITH THE
HIGHER VALUES IN LOCATIONS WITH STRONGER SURFACE HEATING.  DESPITE
THE POTENTIAL FOR WEAKER INSTABILITY...LARGE SCALE ASCENT ASSOCIATED
WITH A SHORT WAVE TROUGH ROTATING AROUND THE ERN PERIPHERY OF THE
OFFSHORE UPPER LOW EXPECTED TO BE SUFFICIENT FOR THUNDERSTORMS TO
DEVELOP BY THIS AFTERNOON.  DEEP LAYER SHEAR WILL BE MORE THAN
ADEQUATE TO SUPPORT ORGANIZED STORMS...WITH STRONG WIND GUSTS AND
HAIL THE PRIMARY THREATS FROM THIS AFTERNOON INTO THE EVENING.

...TN VALLEY SE TO ERN GA/PARTS OF SRN SC...
A COUPLE OF WEAK MID LEVEL IMPULSES ARE EXPECTED TO TRACK ESEWD
ACROSS THE TN VALLEY TOWARD GA/SC TODAY.  ALTHOUGH LOW LEVEL
WINDS/CONVERGENCE SHOULD BE WEAK ALONG THE SURFACE BOUNDARY...
ASCENT WITH THESE IMPULSES...MODERATE INSTABILITY AND 35-40 KT 0-6
KM SHEAR WILL LIKELY SUPPORT A FEW SEVERE STORMS.  HAIL AND STRONG
WIND GUSTS WILL BE THE PRIMARY THREAT...WHILE WEAK LOW-LEVEL WINDS
SHOULD TEND TO MINIMIZE THE TORNADO POTENTIAL.

...LOWER CO RIVER VALLEY NEWD INTO CENTRAL/SRN ROCKIES...
STRONG HEIGHT FALLS/FORCING EXPECTED TO SPREAD ACROSS THIS REGION
TODAY AHEAD OF UPPER TROUGH.  THIS COMBINED WITH STRONG SURFACE
HEATING/OROGRAPHIC ASCENT EXPECTED TO SUPPORT WIDESPREAD CONVECTION
ALONG THE TRACK OF THE UPPER TROUGH.  HOWEVER...WEAK INSTABILITY
SHOULD PRECLUDE A GREATER SEVERE THREAT.  STEEP LAPSE RATES AND
INCREASING DEEP LAYER SHEAR FROM W-E ACROSS THIS REGION SHOULD
SUPPORT A LOW PROBABILITY FOR SEVERE HAIL/STRONG WIND GUSTS.

..PETERS/GRAMS.. 05/22/2006