SWODY1
SPC AC 190438
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1138 PM CDT SUN APR 18 2010
VALID 191200Z - 201200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A HIGHLY AMPLIFIED POLAR BRANCH OF WESTERLIES WILL BE MAINTAINED
THROUGH THE DAY ONE PERIOD...FEATURING AN INTENSIFYING MIDLEVEL
TROUGH OVER THE FAR NERN PACIFIC AND A PRONOUNCED DOWNSTREAM RIDGE
OVER PARTS OF WRN CANADA INTO THE NRN INTER-MOUNTAIN REGION. IN THE
LOWER LATITUDES...A VIGOROUS MIDLEVEL IMPULSE EMBEDDED WITHIN THE
SUBTROPICAL JET WILL TRANSLATE ESEWD ACROSS NWRN MEXICO INTO THE
LOWER RIO GRANDE VALLEY. FARTHER E...A WEAK VORTICITY MAXIMUM WILL
SHIFT EWD ACROSS FL.
IN THE LOW LEVELS...THE PRIMARY FEATURE OF INTEREST WILL BE A LEE
TROUGH OVER THE CNTRL AND SRN HIGH PLAINS WHICH WILL PROVIDE THE
FOCUS FOR ISOLATED TO SCATTERED...DIURNAL STORMS.
...CNTRL/SRN HIGH PLAINS...
SIMILAR TO SUNDAY...LITTLE IN THE WAY OF HEIGHT FALLS/DYNAMIC
FORCING FOR ASCENT IS FORECAST ACROSS THE REGION THROUGH THE DIURNAL
HEATING CYCLE. THERE IS SOME INDICATION THAT A WEAK VORTICITY
MAXIMUM MAY ROTATE SEWD FROM THE NRN HIGH PLAINS...SUPPORTING STORM
FORMATION ALONG NRN EXTENSION OF THE LEE TROUGH OVER PARTS OF ERN WY
INTO WRN PORTIONS OF SD AND NEB. OTHERWISE...EXPECT THAT
CONVERGENCE ALONG THE LEE TROUGH AND TERRAIN INFLUENCES WILL SERVE
AS THE PRIMARY FOCI FOR STORM DEVELOPMENT THIS AFTERNOON AND
EVENING.
DAYTIME HEATING COUPLED WITH STEEP LAPSE RATES AND A SLIGHTLY MORE
MOIST BOUNDARY LAYER ARE EXPECTED TO YIELD STRONGER INSTABILITY THAN
THAT OBSERVED SUNDAY WITH MLCAPE APPROACHING 1000-1200 J/KG. WHEN
COMBINED WITH VERTICAL WIND PROFILES EXHIBITING LIGHT SLY/SELY WINDS
VEERING TO 25-35 KT IN THE MIDLEVELS...ENVIRONMENT WILL BE
SUPPORTIVE OF ORGANIZED/ROTATING UPDRAFTS CAPABLE OF HAIL...SOME OF
WHICH MAY REACH SEVERE LEVELS.
IN ADDITION TO THE HAIL THREAT...THE RELATIVELY DRY SUB-CLOUD LAYER
INDICATES THE POTENTIAL FOR LOCALLY STRONG WIND GUSTS. THIS IS
ESPECIALLY THE CASE SHOULD INDIVIDUAL STORMS MERGE INTO A LARGER
CLUSTER. EXPECT THE HAIL/WIND THREAT TO PERSIST INTO MID/LATE
EVENING PRIOR TO THE COOLING AND RESULTANT STABILIZATION OF THE
BOUNDARY LAYER.
..MEAD/SMITH.. 04/19/2010
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