SPC AC 240045
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0745 PM CDT THU SEP 23 2010
VALID 240100Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS TONIGHT ACROSS PARTS OF THE
UPPER MISSISSIPPI VALLEY...
...UPPER MISSISSIPPI VALLEY...
INSTABILITY IN THE WARM SECTOR OF THE SURFACE CYCLONE...NOW
MIGRATING NORTHEASTWARD THROUGH THE UPPER MISSISSIPPI VALLEY...AND
AHEAD OF A TRAILING SURFACE COLD FRONT...SOUTHWARD THROUGH THE
SOUTHERN PLAINS...REMAINS WEAK. AND POTENTIAL FOR SUBSTANTIVE
FURTHER DESTABILIZATION THROUGH THE REMAINDER OF THE PERIOD APPEARS
LOW. SO THE RISK FOR SEVERE STORMS STILL APPEARS RELATIVELY
LOW...BUT IT IS NOT YET COMPLETELY CLEAR THAT PROBABILITIES ARE LOW
ENOUGH TO REMOVE THE SLIGHT RISK CATEGORICAL OUTLOOK...AT LEAST
ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY.
STRONGER 2 HOUR SURFACE PRESSURE FALLS ARE CURRENTLY SHIFTING
NORTHEASTWARD AHEAD OF THE SURFACE LOW THROUGH THE UPPER GREAT LAKES
REGION...BUT A SECONDARY FALL CENTER MAY NOW BE IN THE PROCESS OF
DEVELOPING NORTHEASTWARD ACROSS EASTERN IOWA INTO WISCONSIN THIS
EVENING. THIS APPEARS TO BE JUST AHEAD OF A REMNANT IMPULSE WHICH
ACCELERATED NORTHEASTWARD OUT OF THE NORTHERN GULF OF CALIFORNIA
VICINITY LAST NIGHT...JUST TO THE EAST/SOUTHEAST OF A MORE PROMINENT
IMPULSE EMERGING FROM THE GREAT BASIN/SOUTHERN PLATEAU.
MODELS SUGGEST THAT DEEPENING OF THE LOWER/MID TROPOSPHERIC CYCLONE
OVER THE UPPER MIDWEST THIS EVENING WILL BE ACCOMPANIED BY
INTENSIFYING WIND FIELDS...INCLUDING AROUND OR IN EXCESS OF 70 KT
...OUT OF THE SOUTH AT 850 MB...ACROSS SOUTHERN AND EASTERN
WISCONSIN. GIVEN THE EXTREME NATURE OF THE LOW-LEVEL SHEAR...AND A
SEASONABLY WARM AND MOIST WARM SECTOR BOUNDARY LAYER AIR MASS
CHARACTERIZED BY SURFACE DEW POINTS NEAR 70F...POTENTIAL FOR THE
DEVELOPMENT OF AN ISOLATED SUPERCELL OR TWO CAPABLE OF PRODUCING
TORNADOES STILL APPEARS TO EXIST. OTHERWISE...PRE-FRONTAL
CONVECTION MAY AID THE DOWNWARD TRANSPORT OF HIGHER MOMENTUM TO THE
SURFACE...WITH STRONG DAMAGING WIND GUSTS POSSIBLE.
..KERR.. 09/24/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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