ZCZC SPCSWOD48 ALL
ACUS48 KWNS 060822
SPC AC 060822
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0322 AM CDT THU MAY 06 2010
VALID 091200Z - 141200Z
...DISCUSSION...
06/00Z ECMWF...GFS AND MEDIUM-RANGE ENSEMBLE GUIDANCE ARE IN
GENERALLY GOOD AGREEMENT IN THE EVOLUTION OF THE LARGE-SCALE PATTERN
THROUGH THE EXTENDED FORECAST PERIOD. ON DAY 4 /SUN MAY 9TH/...THE
NWD RETURN OF A MOIST BOUNDARY LAYER BENEATH THE ERN EDGE OF AN EML
DEVELOPING OVER THE WRN STATES WILL CONTRIBUTE TO A MODERATELY
UNSTABLE AIR MASS OVER WRN TX. THERE IS SOME INDICATION THAT A
WEAK...LOW AMPLITUDE PERTURBATION MAY PROGRESS EWD INTO THE SRN HIGH
PLAINS BY LATE DAY...POSSIBLY SUPPORTING ISOLATED STORM FORMATION
ALONG THE DRY LINE...OR PERHAPS A RETREATING WARM FRONT. VERTICAL
SHEAR WILL BE SUFFICIENT FOR ORGANIZED STORMS INCLUDING SUPERCELLS
WITH THE THREATS FOR HAIL AND PERHAPS TORNADOES. DUE TO
UNCERTAINTIES IN STORM INITIATION AND POTENTIAL COVERAGE...NO SEVERE
WEATHER AREA WILL BE INCLUDED IN THIS FORECAST.
ON DAY 5 /MON MAY 10TH/...MODEL GUIDANCE REMAINS CONSISTENT IN THE
NEWD PROGRESSION OF AN INTENSE...NEGATIVELY-TILTED MIDLEVEL TROUGH
INTO THE CNTRL PLAINS. AN ASSOCIATED...RAPIDLY DEEPENING SURFACE
LOW OVER THE CNTRL HIGH PLAINS WILL DRAW A MOIST AIR MASS
NWD...SETTING THE STAGE FOR A POTENTIAL OUTBREAK OF SUPERCELLS
CAPABLE OF VERY LARGE HAIL AND SIGNIFICANT TORNADOES.
ON DAY 6 /TUE MAY 11TH/...THE SYNOPTIC SYSTEM IS FORECAST TO
DE-AMPLIFY/FILL AS IS PROGRESSES NEWD INTO THE UPPER GREAT LAKES.
SEVERE STORMS WILL REMAIN POSSIBLE ALONG THE COLD FRONT FROM THE
UPPER MIDWEST INTO OZARK PLATEAU. HOWEVER...GIVEN THE EXPECTED POOR
LAPSE RATES...WEAKENING SYSTEM AND POTENTIAL FOR ONGOING/WIDESPREAD
STORMS...THE POTENTIAL FOR A MORE WIDESPREAD SEVERE WEATHER EVENT
REMAINS IN QUESTION.
ON DAY 7 /WED MAY 12TH/...THE ECMWF AND GFS ARE IN RELATIVELY GOOD
AGREEMENT IN THE SLOW EWD PROGRESSION OF A LARGE-SCALE TROUGH OVER
THE WRN STATES. HOWEVER...DIFFERENCES DO EXIST IN THE LOCATION OF
NE-SW ORIENTED BAROCLINIC ZONE WHICH WILL STRETCH FROM WEAKENING LOW
PRESSURE OVER THE GREAT LAKES REGION INTO THE SRN PLAINS. THIS
FRONTAL LOCATION BECOMES EVEN MORE PROBLEMATIC WHEN FACTORING IN THE
POSSIBILITY THAT EPISODIC TSTM ACTIVITY FOR THE PREVIOUS TWO DAYS
COULD POTENTIALLY DISPLACE THE EFFECTIVE FRONT EVEN FARTHER S.
WHILE THE ENVIRONMENT ALONG AND TO THE S OF THIS BOUNDARY WILL BE
SUPPORTIVE OF SEVERE STORMS...UNCERTAINTY IN ITS LOCATION PRECLUDES
THE ISSUANCE OF AN ADDITIONAL SEVERE WEATHER AREA.
..MEAD.. 05/06/2010
