DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 250921
SWOD48
SPC AC 250920

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0320 AM CST FRI JAN 25 2013

VALID 281200Z - 021200Z

...DISCUSSION...
GENERAL AGREEMENT EXISTS AMONGST THE GFS/EC/UK/CMC GLOBAL MODELS IN
THE EVOLUTION OF A LARGE SCALE POSITIVE TILT TROUGH ACROSS THE WRN
U.S. THROUGH D4/MON. HOWEVER...IT IS IMMEDIATELY THEREAFTER AND
BEYOND WHEN SUBSTANTIAL DIFFERENCES APPEAR AND PERSIST AMONGST THE
MEDIUM RANGE GUIDANCE...THUS INTRODUCING CONSIDERABLE UNCERTAINTY IN
THE FORECAST FOR NEXT WEEK.

THE ECMWF EXHIBITS THE GREATEST DEPARTURE FROM PRIOR RUNS AND IS AN
OUTLIER IN DEVELOPING A CUTOFF LOW WITHIN THE BASE OF THE POSITIVE
TILT TROUGH ACROSS THE SOUTHWEST AND BAJA THROUGH D5/TUE. THE
GFS...AND TO SOME EXTENT THE OTHER GLOBAL MODELS AND GFS
ENSEMBLE...MAINTAIN A MORE PROGRESSIVE AND PHASED DEEP UPPER TROUGH
AND STRONGER COLD FRONT THAT SPREAD EAST AND SOUTH ACROSS MID/LOWER
MS VALLEY THROUGH D6/WED. BUT...EVEN AMONGST THE GFS ENSEMBLE
MEMBERS...UNCERTAINTY IN THE AMPLITUDE OF THIS TROUGH IS HIGH WITH
THE STANDARD DEVIATION IN 500MB HEIGHTS ACROSS THE CNTRL U.S.
EXCEEDING 90M AT THE 120H FORECAST VALID D5/TUE EVENING.

DESPITE THE SPREAD IN GFS ENSEMBLE MEMBERS...THERE REMAINS A LOW
PROBABILITY SEVERE WEATHER THREAT FROM ARKLATEX TO MS DELTA REGIONS
AS THE COLD FRONT ASSOCIATED WITH THE UPPER TROUGH DEVELOPS INTO AN
AXIS OF POTENTIAL INSTABILITY THROUGH D5/TUE EVENING. WITH LATEST
MODEL SOLUTIONS AND ENSEMBLE MEMBERS EXHIBITING SUCH DIVERGENT
OUTCOMES HOWEVER...FORECAST CONFIDENCE IN A MORE WIDESPREAD SEVERE
WEATHER THREAT HAS DECREASED SINCE YESTERDAY. THUS...PREDICTABILITY
APPEARS TOO LOW TO MAINTAIN A SEVERE WEATHER AREA AT THIS TIME.

..CARBIN.. 01/25/2013

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.