SPC AC 150536
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1236 AM CDT SAT JUL 15 2006
VALID 151200Z - 161200Z
...NO SVR TSTM AREAS FORECAST...
MODELS INDICATE THAT A BROADENING SUBTROPICAL RIDGE...CENTERED NEAR
THE FOUR CORNERS...WILL CONTINUE TO EXPAND EASTWARD THROUGH MUCH OF
THE MID/UPPER MISSISSIPPI VALLEY AND GREAT LAKES/OHIO VALLEY DURING
THIS FORECAST PERIOD. THIS IS FORECAST TO OCCUR AS THE EXIT REGION
OF A SEASONABLY STRONG ZONAL MID/UPPER JET STREAK...JUST NORTH OF
THE CANADIAN/U.S. BORDER...NOSES THROUGH ONTARIO AND QUEBEC. THE
MAIN PORTION OF A WEAKENING DOWNSTREAM UPPER TROUGH IS PROGGED TO
LIFT OUT OF WESTERN ONTARIO AND THE LOWER GREAT LAKES THROUGH THE
CANADIAN MARITIMES AND NEW ENGLAND...BUT A LINGERING TRAILING SHEAR
AXIS WILL PROGRESS SOUTH AND EAST OF THE CENTRAL/SOUTHERN
APPALACHIANS. THIS WILL WEAKEN SOUTHEASTERN SUBTROPICAL RIDGE.
...ATLANTIC COAST STATES...
UPPER TROUGH/SHEAR AXIS APPEARS LIKELY TO PROVIDE THE FOCUS FOR THE
PRIMARY CONVECTIVE DEVELOPMENT TODAY...AS INHIBITION ALONG/AHEAD OF
IT REMAINS WEAK. NORTH OF THE MID ATLANTIC STATES...MODERATE
SOUTHWESTERLY MID-LEVEL FLOW WILL ENHANCE STORM MOTIONS AND DEEP
LAYER SHEAR SOMEWHAT...WHILE STRONGER HEATING/STEEPER LOW-LEVEL
LAPSE RATES COMPENSATE FOR WEAKER SHEAR/FLOW TO THE SOUTH...IN THE
LEE OF THE CENTRAL/SOUTHERN APPALACHIANS. WIDELY SCATTERED STRONG
STORMS APPEAR POSSIBLE...SOME OF WHICH COULD PRODUCE GUSTY
WINDS/HAIL APPROACHING OR BRIEFLY EXCEEDING SEVERE LIMITS DURING THE
AFTERNOON AND EARLY EVENING HOURS.
...UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES...
MODELS SUGGEST THAT A WEAK MID-LEVEL IMPULSE PROGRESSING THROUGH THE
BELT OF WESTERLIES NEAR THE INTERNATIONAL BORDER WILL SUPPORT A
STRENGTHENING SOUTHWESTERLY LOW-LEVEL JET...NORTHEAST OF THE MID
MISSOURI VALLEY INTO THE MINNESOTA ARROWHEAD BY LATE THIS AFTERNOON.
THIS MAY BE ACCOMPANIED BY AN INFLUX OF LOWER/MID TROPOSPHERIC
MOISTURE...CONTRIBUTING TO POTENTIAL INSTABILITY BENEATH A RATHER
SUBSTANTIAL MID-LEVEL CAP.
CONSIDERABLE UNCERTAINTY EXISTS...BUT STRONG HEATING/LOW-LEVEL WARM
ADVECTION MAY BE ENOUGH TO INITIATE CONVECTIVE DEVELOPMENT ACROSS
PARTS OF CENTRAL/NORTHERN MINNESOTA LATE THIS AFTERNOON. IF THIS
OCCURS...A DEEP MIXED BOUNDARY LAYER...WITH CAPE OF 1000 TO 2000
J/KG...WILL BE SUPPORTIVE OF SEVERE STORMS WITH DAMAGING WINDS AND
HAIL IN MODERATE TO STRONGLY SHEARED FLOW. AN ISOLATED SUPERCELL
APPEARS POSSIBLE. HOWEVER...AT THIS TIME...SIGNIFICANT CONVECTIVE
DEVELOPMENT SEEMS MOST PROBABLE AFTER DARK...NORTH OF THE
INTERNATIONAL BORDER...FROM PARTS OF WESTERN ONTARIO INTO NORTHERN
LAKE SUPERIOR.
...ARIZONA...
MOISTURE LEVELS SEEM LIKELY TO REMAIN A BIT LOW...LIKELY LIMITING
MAGNITUDE OF DESTABILIZATION TODAY. HOWEVER...20-30+ KT EASTERLY
MID LEVEL FLOW DEVELOPING TO THE SOUTH OF UPPER HIGH CENTER WILL AID
PROPAGATION OF STORMS OFF THE HIGHER TERRAIN INTO THE LOWER DESERTS
LATE THIS AFTERNOON AND EVENING. AND...INVERTED-V PROFILES ACROSS
THE LOWER DESERTS WILL BE SUPPORTIVE OF AT LEAST ISOLATED
MICROBURSTS BEFORE STORMS DIMINISH WITH LOSS OF HEATING.
..KERR/JEWELL.. 07/15/2006
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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