SWODY1
SPC AC 140054
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 PM CDT FRI JUN 13 2008
VALID 140100Z - 141200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS EVE ACROSS PARTS OF THE
UPR OH VLY/LWR GREAT LAKES....
...THERE IS A SLGT RISK OF SVR TSTMS THIS EVE FROM PARTS OF THE
OZARK PLATEAU INTO THE LWR OH VALLEY....
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF WRN/SWRN TX....
...SYNOPSIS...
THE UPPER CLOSED LOW...WHICH HAS BEEN PROMINENT ACROSS THE NORTH
CENTRAL U.S. THE PAST COUPLE OF DAYS...CONTINUES TO WEAKEN AND LIFT
NORTH OF THE CENTRAL CANADIAN/U.S. BORDER...TOWARD THE HUDSON/JAMES
BAY REGION. BUT...A SEASONABLY STRONG CYCLONIC FLOW LINGERS SOUTH
OF THE BORDER...FROM THE NORTHERN ROCKIES THROUGH THE UPPER HALF OF
THE MISSISSIPPI VALLEY AND GREAT LAKES REGION. THE MOST SIGNIFICANT
IMPULSE EMBEDDED WITHIN THIS REGIME IS NOW LIFTING THROUGH THE UPPER
MISSISSIPPI VALLEY...AND GUIDANCE INDICATES THAT THIS FEATURE WILL
CONTINUE EAST NORTHEASTWARD THROUGH THE UPPER GREAT LAKES REGION BY
12Z SATURDAY. AS THIS OCCURS...THE BELT OF 50+ KT 500 MB FLOW NOW
OVER THE LOWER MISSOURI VALLEY IS PROGGED TO WEAKEN/LIFT THROUGH
LOWER MICHIGAN BY 14/06Z. THIS COULD BE ACCOMPANIED BY SOME
STRENGTHENING OF SOUTHWESTERLY 850 MB FLOW...PERHAPS UP TO 30-40
KTS...ACROSS THE UPPER OHIO VALLEY INTO THE LOWER GREAT LAKES.
...S CNTRL PLAINS INTO TN/OH VALLEYS AND LWR GREAT LAKES...
ONGOING STORMS ALONG OUTFLOW BOUNDARY ACROSS NORTHERN ARKANSAS INTO
WESTERN KENTUCKY/TENNESSEE ARE OCCURRING ALONG THE SOUTHERN FRINGE
OF THE LOWER MISSOURI VALLEY MID-LEVEL JET. AND...THIS MAY CONTINUE
TO CONTRIBUTE TO SUFFICIENT DEEP LAYER SHEAR/MOMENTUM FOR A SOMEWHAT
ENHANCED RISK FOR DAMAGING WIND GUSTS IN STRONGER CONVECTION THROUGH
THE 14/03-05Z TIME FRAME. BUT...AS THE MID-LEVEL JET WEAKENS/LIFTS
NORTHEASTWARD...SEVERE POTENTIAL IS EXPECTED TO GRADUALLY DIMINISH
THIS EVENING.
OTHERWISE...THE BULK OF ONGOING CONVECTIVE DEVELOPMENT HAS ALREADY
BECOME DISPLACED TO THE SOUTH/EAST OF THE STRONGER FLOW. AND...
WITH THE ONSET OF BOUNDARY LAYER COOLING...THE SEVERE THREAT IS
BECOMING MARGINALIZED. AN EXCEPTION COULD BE WITH STORMS NOW
DEVELOPING INTO THE UPPER OHIO VALLEY/LOWER GREAT LAKES REGION...
WHERE STRENGTHENING 850 FLOW COULD ENHANCE STORM MOTIONS...AND
POTENTIAL FOR DAMAGING WIND GUSTS...BY 14/03-06Z.
ADDITIONALLY...GIVEN WEAKENED INHIBITION ON THE SOUTHERN PERIPHERY
OF THE BROADER SCALE UPPER TROUGH...NEW CONVECTIVE DEVELOPMENT STILL
APPEARS POSSIBLE THIS EVENING ALONG A STALLING OUTFLOW BOUNDARY
ACROSS PARTS OF CENTRAL/EASTERN OKLAHOMA. LARGE-SCALE MID-LEVEL
SUBSIDENCE IN THE WAKE OF THE IMPULSE LIFTING TOWARD THE GREAT LAKES
HAS SUPPRESSED DEVELOPMENT TO THIS POINT. BUT...AT LEAST WEAK
UPWARD VERTICAL MOTION...ASSOCIATED WITH THE GLANCING INFLUENCE OF
ANOTHER MORE SUBTLE IMPULSE NOW MIGRATING EAST SOUTHEAST OF THE
CENTRAL ROCKIES...MAY DEVELOP LATER THIS EVENING/ OVERNIGHT.
...SOUTHERN HIGH PLAINS...
ONGOING CONVECTIVE DEVELOPMENT NEAR WEAKENING COLD FRONT/DRY LINE
OVER PARTS OF THE TEXAS SOUTH PLAINS INTO SOUTHWEST TEXAS APPEARS
ROOTED IN A HOT...DEEPLY MIXED BOUNDARY LAYER TOPPED BY SUFFICIENTLY
STEEP MID-LEVEL LAPSE RATES FOR MIXED LAYER CAPE IN EXCESS OF 2000
J/KG. AND...THIS IS OCCURRING IN THE PRESENCE OF MODERATE DEEP
LAYER SHEAR ASSOCIATED WITH STRONG VEERING OF WIND FIELDS FROM LIGHT
AND SOUTHEASTERLY AT LOWER LEVELS TO LIGHT NORTHWESTERLY AT AROUND
500 MB. UPPER SUPPORT BENEATH THE SUBTROPICAL RIDGE IS
MINIMAL...BUT NOCTURNAL STRENGTHENING OF A SOUTHERLY LOW-LEVEL JET
MAY MAINTAIN VIGOROUS STORMS...CAPABLE OF GUSTY WINDS AND LARGE
HAIL...THROUGH THE 14/03-06Z TIME FRAME.
..KERR.. 06/14/2008
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