SPC AC 171730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT SAT JUL 17 2010
VALID 181200Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE MIDWEST/OH
VALLEY/GREAT LAKES...
...SYNOPSIS...
THE OVERALL LARGE SCALE PATTERN WILL FLUCTUATE LITTLE THROUGH
SUNDAY...AS A BROAD UPPER RIDGE REMAINS CENTERED OVER THE SOUTHWEST
STATES...WHILE A SEASONALLY STRONG BELT OF WESTERLIES REMAINS OVER
THE NORTHERN TIER OF THE CONUS AND SOUTHERN CANADA.
...LOWER MO VALLEY/MIDWEST/OH VALLEY/GREAT LAKES...
MULTIPLE CLUSTERS OF TSTMS ARE LIKELY TO BE ONGOING WITHIN A
CORRIDOR FROM THE LAKE SUPERIOR/LAKE MI VICINITIES SOUTHWESTWARD TO
IA/NORTHERN MO SUNDAY MORNING. THE PRIMARY FOCUS WILL BE ON ONE OR
MORE EARLY DAY POTENTIALLY ORGANIZED/SEVERE MCS/S...WHICH SEEM MOST
PROBABLE TO BE ONGOING ACROSS PORTIONS OF NORTHERN MO OR PERHAPS
SOUTHERN IA/WESTERN IL SUNDAY MORNING. AIDED BY A VEERING/BUT
MODESTLY WEAKENING LOW LEVEL JET...THE ONGOING/PRESUMABLY
WELL-ORGANIZED SYSTEM/S...AND PERHAPS MORE LIKELY RESULTANT
OUTFLOWS/MCV...MAY CONTINUE TO POSE AN ISOLATED SEVERE
THREAT/CONTRIBUTE TO AN AFTERNOON REINVIGORATION DOWNSTREAM ACROSS
THE OH VALLEY. ADDITIONAL DEEP CONVECTIVE DEVELOPMENT CAN BE
EXPECTED BY EARLY/MID AFTERNOON ALONG/JUST AHEAD OF THE
EAST-SOUTHEAST ADVANCING COLD FRONT FROM LOWER MI SOUTHWESTWARD INTO
IL/INDIANA AND EVENTUALLY WESTERN/NORTHERN OH.
WITHIN THE NON-CONVECTIVELY OVERTURNED/PRE-COLD FRONTAL
AIRMASS...THE BOUNDARY LAYER WILL BECOME QUITE UNSTABLE /2000-3500 J
PER KG MLCAPE/...ATTRIBUTABLE TO AMPLE HEATING AND A BROAD EXTENT OF
LOWER 70S F SURFACE DEWPOINTS/HIGH PWAT VALUES. OVERALL...A
LINEAR-TYPE CONVECTIVE MODE SHOULD BE DOMINANT...WITH DAMAGING WINDS
AS THE MAIN HAZARD...ALSO SOME SEVERE HAIL/PERHAPS A TORNADO WILL BE
POSSIBLE AS WELL.
FARTHER WEST ACROSS THE LOWER MO VALLEY VICINITY...WHILE MUCH OF THE
FRONTAL ZONE SHOULD REMAIN CAPPED THROUGH THE DAYTIME HOURS...IT IS
CONCEIVABLE THAT TSTMS /SOME STRONG TO SEVERE/ SHOULD INCREASE
SUNDAY NIGHT...PERHAPS ACROSS FAR NORTHEAST KS/FAR SOUTHEAST NEB
INTO SOUTHERN IA/NORTHERN MO. THIS WOULD LARGELY BE ATTRIBUTABLE TO
A NOCTURNALLY INCREASING LOW LEVEL JET/WARM ADVECTION REGIME
IMPINGING ON THE EFFECTIVE/EARLY DAY MCS REINFORCED EFFECTIVE
FRONTAL ZONE.
...NORTH-CENTRAL HIGH PLAINS...
LOW LEVEL MOIST/UPSLOPE TRAJECTORIES WILL INCREASE ACROSS THE
NORTH-CENTRAL HIGH PLAINS AS SURFACE HIGH PRESSURE BECOMES
ESTABLISHED/SHIFTS EASTWARD ACROSS THE NORTHERN PLAINS/UPPER
MIDWEST. IT SEEMS THAT NORTHEAST WY/SOUTHEAST MT/WESTERN SD...AS
WELL AS NORTHEAST CO...WILL BE PREFERRED AREAS FOR TSTM DEVELOPMENT
SUNDAY AFTERNOON/EARLY EVENING. INITIALLY MODEST MOISTURE /NORTH/
AND/OR WARM TEMPERATURES ALOFT /SOUTH/ MAY KEEP THE OVERALL SEVERE
POTENTIAL LIMITED...BUT AT LEAST A FEW STORMS/SUPERCELLS CAPABLE OF
SEVERE HAIL/GUSTY WINDS SEEM PROBABLE.
...SOUTHERN AZ...
MOIST AIRMASS WITH AROUND 15-20 KT OF EASTERLY STEERING FLOW ALOFT
WILL EXIST CROSS SOUTHERN AZ ON SUNDAY. HOWEVER...CLOSE PROXIMITY OF
THE SOUTHWEST STATES ANTICYCLONE/WEAK LAPSE RATES ALOFT MAY TEMPER
STORM VIGOR/LIKELIHOOD OF STORMS REACHING THE DESERT FLOOR.
..GUYER.. 07/17/2010
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
|
