949
ACUS48 KWNS 220919
SWOD48
SPC AC 220917
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0417 AM CDT WED MAY 22 2019
VALID 251200Z - 301200Z
..DISCUSSION
MODELS REMAIN IN REASONABLE AGREEMENT WITH REGARD TO EVOLUTION OF
THE SYNOPTIC PATTERN THROUGH DAY 5, BUT CONSIDERABLE DIFFERENCES
ARISE BY DAY 6 AND BEYOND ESPECIALLY REGARDING EVOLUTION OF WESTERN
U.S. CUTOFF UPPER LOW.
DAY 4 (SATURDAY) SHORTWAVE TROUGH WILL CREST UPPER RIDGE AND MOVE
THROUGH THE GREAT LAKES DURING THE DAY BEFORE TURNING SOUTHEAST INTO
THE NORTHEAST STATES SATURDAY NIGHT. SURFACE LOW ACCOMPANYING THIS
FEATURE WILL MOVE THROUGH EASTERN CANADA WHILE TRAILING COLD FRONT
ADVANCES SOUTHEAST THROUGH THE GREAT LAKES AND NORTHEAST STATES.
WESTERN EXTENSION OF FRONT SHOULD STALL ACROSS THE CENTRAL PLAINS. A
DRYLINE WILL RESIDE NEAR THE TX/NM BORDER. LOW 60S F DEWPOINTS WILL
ADVECT THROUGH THE OH VALLEY WARM SECTOR SATURDAY CONTRIBUTING TO
MODEST INSTABILITY. THUNDERSTORMS MAY DEVELOP ALONG AND AHEAD OF THE
COLD FRONT LOCATED ACROSS THE SOUTHERN GREAT LAKES AND SPREAD
SOUTHEAST INTO THE OH VALLEY AND A PORTION OF THE NORTHEAST STATES.
STRONG UNIDIRECTIONAL WIND PROFILES ATTENDING THE NORTHERN-STREAM
TROUGH WILL BE SUFFICIENT FOR A FEW ORGANIZED SEVERE STORMS. OTHER
STRONG TO SEVERE STORMS WILL BE POSSIBLE ALONG PORTION OF THE FRONT
OVER THE CENTRAL PLAINS WHERE STRONG INSTABILITY WILL RESIDE.
DEVELOPMENT ALONG WEST TEXAS DRYLINE REMAINS UNCERTAIN AT THIS TIME
GIVEN APPARENT WEAK CONVERGENCE AND PRESENCE OF LOW-AMPLITUDE RIDGE.
DAY 5 (SUNDAY) SOME SEVERE STORM POTENTIAL WILL PERSIST IN VICINITY
OF EAST-WEST FRONT FROM THE PLAINS TO THE OH VALLEY AS WELL AS ALONG
SOUTHERN PLAINS DRYLINE. BUT LOCATION OF BEST SEVERE STORM POTENTIAL
WILL BE DEPENDENT ON PREVIOUS DAY'S STORMS AND OUTFLOW.
BY DAY 7 (TUESDAY) BOTH GFS AND ECMWF AS WELL AS SOME SREF MEMBERS
INDICATE AN UPPER SPEED MAX WILL ROTATE THROUGH THE BASE OF THE
WESTERN U.S. UPPER TROUGH AND INTO THE SOUTHERN AND CENTRAL PLAINS.
THIS WOULD SUGGEST INCREASING SEVERE POTENTIAL OVER THE PLAINS BY
THAT TIME, AND SEVERE PROBABILITIES WILL NEED TO BE INTRODUCED IN
LATER UPDATES IF MODELS BECOME MORE CONSISTENT.
..DIAL.. 05/22/2019
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