(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 120740
SPC AC 120740
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0240 AM CDT Sun May 12 2019
Valid 151200Z - 201200Z
...DISCUSSION...
On Wed/D4-Thur/D5, an upper ridge will move east across the Plains,
as a large upper trough develops across the West, with upper low
over the Great Basin. By Fri/D6 into Sat/D7, severe weather appears
likely across parts of the central and southern Plains, as mid to
possibly upper 60s F dewpoints return north aided by a southerly
low-level jet. The ECMWF ensemble has reasonably low spread, and has
a deeper solution with the trough compared to the GFS ensemble
members. In either case, the threat for severe weather is likely to
increase on Fri/D6 into Sat/D7, and 15% probabilities have been
introduced for Fri/D6. Increasing flow aloft with a substantial
low-level jet and moisture should support supercells along the
dryline Fri afternoon and evening. Predictability related to the
previous day's storms, as well as increased model spread, will
preclude a Sat/D7 area farther east.
Severe storms are possible as well on Fri/D6 across parts of the
northern Plains, from the Dakotas into Minnesota with an MCS pattern
in a warm advection regime. However, predictability for this
scenario is low at this time.
..Jewell.. 05/12/2019
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