DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 171732
SWODY2
SPC AC 171730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT MON JUN 17 2013

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SOUTHERN
HIGH PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NORTHWEST AND
NORTH CENTRAL MONTANA...

...SYNOPSIS...
BETWEEN GENERALLY FLAT UPPER RIDGING OVER THE SUBTROPICAL PACIFIC
AND A BLOCKING UPPER HIGH CENTER OVER ALASKA...A BELT OF STRONGER
WESTERLIES EXTENDS ACROSS THE MID-LATITUDE PACIFIC INTO THE PACIFIC
COAST REGION. ON THE LEADING EDGE OF THIS REGIME...MODELS INDICATE
THAT A BROAD...DEEP MID-LEVEL CLOSED LOW...AND TROUGHING TO THE
SOUTH...WILL ELONGATE AND PIVOT INLAND IN NEGATIVELY TILTED FASHION
ACROSS THE PACIFIC NORTHWEST INTO THE NORTHERN GREAT BASIN AND
NORTHERN INTERMOUNTAIN REGION BY 12Z WEDNESDAY.

DOWNSTREAM...ANOTHER BELT OF STRONGER WESTERLIES CURVE IN BROADLY
CYCLONIC FASHION ACROSS THE GREAT LAKES REGION AND NORTHEAST. AS
ONE SIGNIFICANT EMBEDDED IMPULSE...NOW DIGGING TO THE SOUTHEAST OF
HUDSON BAY...CONTINUES EASTWARD THROUGH THE CANADIAN MARITIMES AND
NORTHERN NEW ENGLAND...AHEAD OF ANOTHER MORE SIGNIFICANT CLOSED LOW
DIGGING TO THE NORTH OF HUDSON BAY...THIS BELT OF FLOW IS FORECAST
TO WEAKEN DURING THIS PERIOD. HOWEVER...AN IMPULSE WITHIN A WEAKER
BELT OF CYCLONIC FLOW TO THE SOUTH...LIKELY WILL DIG FROM THE UPPER
MISSISSIPPI VALLEY THROUGH THE OHIO VALLEY.

ELSEWHERE...IN BETWEEN THE CYCLONIC REGIMES OVER THE WEST AND
EAST...UPPER RIDGING WITH WEAK FLOW IS EXPECTED PREVAIL ACROSS THE
PLAINS. MEANWHILE...GENERALLY WEAK ZONAL FLOW IS EXPECTED ACROSS
MUCH OF THE SOUTHERN TIER STATES.

ASSOCIATED WITH THIS PATTERN...STEEP MID-LEVEL LAPSE RATES WILL
MOSTLY BE CONFINED TO THE INTERMOUNTAIN WEST...ROCKIES AND HIGH
PLAINS REGION...WHILE HIGHER MOISTURE CONTENT AIR /CHARACTERIZED BY
PRECIPITABLE WATER AOA 1.75 INCHES/ BECOMES CONFINED TO THE SOUTHERN
HIGH PLAINS...GULF STATES AND SOUTHERN/MID ATLANTIC COAST STATES.

...NORTHWESTERN AND NORTH CENTRAL MONTANA...
BENEATH DIFLUENT AND INCREASINGLY DIVERGENT UPPER FLOW...AT LEAST
SCATTERED STORM DEVELOPMENT IS EXPECTED TUESDAY AFTERNOON AND
EVENING ACROSS THE MOUNTAINS...ON THE LEADING EDGE OF STRONGER
MID-LEVEL COOLING ASSOCIATED WITH THE APPROACHING UPPER TROUGH.
WITH STEEP LAPSE RATES SUPPORTING AT LEAST WEAK TO MODERATE
CAPE...STRENGTHENING SOUTHERLY MID/UPPER FLOW MAY BECOME SUPPORTIVE
OF SUPERCELLS CAPABLE OF PRODUCING SEVERE HAIL AND LOCALLY STRONG
SURFACE GUSTS.

ADDITIONAL DEVELOPMENT...INCLUDING THE RISK FOR SUPERCELLS...EAST OF
THE HIGHER TERRAIN INTO PARTS OF NORTH CENTRAL MONTANA IS POSSIBLE
DURING THE EVENING HOURS...ON THE SOUTHERN FRINGE OF A STRENGTHENING
LOWER/MID TROPOSPHERIC WARM ADVECTION REGIME FOCUSED GENERALLY
ACROSS PARTS OF SOUTHERN ALBERTA/SASKATCHEWAN.

...HIGH PLAINS...
MID/UPPER FORCING FOR CONVECTIVE DEVELOPMENT REMAINS UNCLEAR. BUT
THERMODYNAMIC PROFILES ARE EXPECTED TO BE CHARACTERIZED BY STEEP
MID-LEVEL LAPSE RATES AND SIZABLE CAPE...IN THE PRESENCE OF STRONG
DEEP LAYER SHEAR /MOSTLY DUE TO PRONOUNCED VEERING OF WEAK TO MODEST
SOUTHEASTERLY LOW-LEVEL FLOW TO MODEST WESTERLY FLOW ALOFT/. THIS
ENVIRONMENT APPEARS CONDUCIVE TO VIGOROUS CONVECTIVE DEVELOPMENT OFF
THE HIGHER TERRAIN...WITH ISOLATED SUPERCELLS AND THE POTENTIAL FOR
THE EVOLUTION OF ORGANIZED STORM CLUSTERS...WITH GREATEST
CONCENTRATION/PROBABILITIES PERHAPS ACROSS PARTS OF SOUTHEAST
COLORADO AND EASTERN NEW MEXICO INTO WESTERN TEXAS.

...OHIO VALLEY INTO SRN NEW ENGLAND AND NRN MID ATLANTIC...
GIVEN AT LEAST MODERATE DESTABILIZATION WITH DAYTIME HEATING AHEAD
OF A SOUTHWARD ADVANCING COLD FRONT...THE REMNANT BELT OF MODEST
WESTERLY MID-LEVEL FLOW COULD ENHANCE ASSOCIATED CONVECTIVE
DEVELOPMENT TUESDAY AFTERNOON...SUPPORTING AT LEAST LOW
PROBABILITIES FOR SEVERE WIND AND HAIL.

..KERR.. 06/17/2013

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