SWODY2
SPC AC 190531
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 AM CDT SAT MAR 19 2011
VALID 201200Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
THE REMNANTS OF A SIGNIFICANT SHORT WAVE TROUGH...LIKELY REACHING
THE NORTHERN ROCKIES BY 12Z SUNDAY...ARE PROGGED TO ACCELERATE
EASTWARD WITHIN CONFLUENT FLOW ACROSS THE NORTHERN PLAINS INTO THE
UPPER GREAT LAKES REGION BY 12Z MONDAY. WEAK HEIGHT FALLS MAY
SUPPRESS MID-LEVEL RIDGING AS FAR SOUTH AS THE NORTH CENTRAL PLAINS
AND MID MISSOURI VALLEY DURING THE DAY SUNDAY...AND THE OHIO VALLEY
SUNDAY NIGHT...BUT RIDGING IS EXPECTED TO REMAIN GENERALLY STRONG
FROM THE SOUTHERN PLAINS INTO THE SOUTHEAST. MID-LEVEL HEIGHTS
APPEAR LIKELY TO BUILD QUICKLY IN THE WAKE OF THE UPPER
IMPULSE...ACROSS THE CENTRAL AND NORTHERN ROCKIES INTO THE ADJACENT
PLAINS...AS A MUCH MORE SIGNIFICANT SHORT WAVE TROUGH GRADUALLY
TURNS INLAND ACROSS THE CALIFORNIA COAST SUNDAY NIGHT.
AT LOWER LEVELS...MODELS INDICATE THAT A MODEST SURFACE WAVE MAY
DEVELOP ALONG A RETREATING FRONTAL ZONE FROM THE NORTH CENTRAL
PLAINS INTO THE GREAT LAKES DURING THE PERIOD. HOWEVER...INFLOW OF
MOISTURE OFF THE WESTERN GULF OF MEXICO WILL REMAIN INHIBITED BY
RIDGING EXTENDING FROM A HIGH CENTER SHIFTING OFF THE NORTH ATLANTIC
COAST...WEST SOUTHWESTWARD THROUGH THE WESTERN GULF COAST. HIGHER
BOUNDARY LAYER MOISTURE CHARACTERIZED BY SURFACE DEW POINTS NEAR 60F
APPEARS LIKELY TO BE CONFINED TO NARROW CORRIDORS ALONG REMNANTS OF
A FRONTAL ZONE ACROSS PARTS OF THE LOWER OHIO/TENNESSEE VALLEYS AND
THE FLORIDA PENINSULA...AS WELL AS ALONG A DRY LINE INTO THE
VICINITY OF THE FRONTAL WAVE...FROM WESTERN OKLAHOMA INTO IOWA LATE
IN THE AFTERNOON. WHILE MODEST DESTABILIZATION MAY OCCUR ACROSS
THESE AREAS WITH DAYTIME HEATING ...CONVECTIVE POTENTIAL IS EXPECTED
TO BE SUPPRESSED BY CONSIDERABLE MID-LEVEL INHIBITION AND GENERALLY
SUBSIDENT FLOW ALOFT.
HIGHEST THUNDERSTORM PROBABILITIES THROUGH THE PERIOD ARE STILL
EXPECTED TO BE IN ASSOCIATION WITH WEAK DESTABILIZATION WITHIN
LOW-LEVEL WARM ADVECTION TO THE NORTH AND EAST OF THE RETREATING
FRONT. ACTIVITY MAY BE ONGOING AT 12Z SUNDAY ACROSS UPPER PORTIONS
OF THE MIDDLE MISSISSIPPI VALLEY...BEFORE DEVELOPING NORTHWARD INTO
PARTS OF THE UPPER GREAT LAKES DURING THE DAY... THEN EASTWARD
ACROSS THE GREAT LAKES AND OHIO VALLEY DURING THE LATTER HALF OF THE
PERIOD.
...SOUTH CENTRAL PLAINS INTO MID MISSOURI VALLEY...
MIXED LAYER CAPE PROBABLY WILL EXCEED 1000 J/KG BY PEAK HEATING NEAR
THE DRY LINE...LIKELY TO EXTEND ACROSS WESTERN OKLAHOMA INTO THE
VICINITY OF A COLD FRONT ACROSS NORTHEAST KANSAS LATE SUNDAY
AFTERNOON...PERHAPS NORTHEASTWARD WITHIN A PRE-FRONTAL CORRIDOR TO
THE DEVELOPING LOW OVER IOWA AS WELL. BEFORE MID-LEVEL HEIGHTS
BEGINS TO RISE...LOW-LEVEL FORCING NEAR THE LOW MAY BE SUFFICIENT TO
SUPPORT ISOLATED STORMS IN THE PRESENCE OF STRONG SHEAR FAVORABLE
FOR SUPERCELLS. LOW-LEVEL HODOGRAPHS SHOULD BE LARGE AND CLOCKWISE
CURVED ALONG A 40+ KT SOUTHERLY LOW-LEVEL JET...BENEATH 50-70 KT
WESTERLY 500 MB FLOW. HOWEVER...IT IS STILL NOT CLEAR WHETHER THIS
ACTIVITY WILL FORM WITHIN THE UNSTABLE WARM SECTOR BOUNDARY
LAYER...OR IN THE VICINITY OF A WARM FRONT EXTENDING TO THE EAST OF
THE LOW. REGARDLESS...THE TENDENCY MAY BE FOR ACTIVITY TO QUICKLY
SPREAD EASTWARD ABOVE A RAIN-COOLED AND STABLE BOUNDARY LAYER ACROSS
EASTERN IOWA AND NORTHERN ILLINOIS...BEFORE DIMINISHING SUNDAY
EVENING.
OTHERWISE...AN ISOLATED STORM OR TWO STILL APPEARS POSSIBLE ALONG
THE DRY LINE ACROSS THE CENTRAL PLAINS...MAINLY WHERE SURFACE
HEATING MAXIMIZES AND LOCALLY WEAKENS INHIBITION. IF THIS
OCCURS...THE ENVIRONMENT WILL FAVOR SUPERCELLS...BUT IT IS NOT CLEAR
HOW LONG STORMS WILL SURVIVE AS THEY PROPAGATE EAST OF THE DRY
LINE...WHICH MAY BEGIN TO SLOWLY RETREATING NORTHWESTWARD DURING THE
EVENING HOURS.
..KERR.. 03/19/2011
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