(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.
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 220900
SPC AC 220900
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CDT SAT OCT 22 2016
VALID 251200Z - 301200Z
00Z ECMWF/GFS SHOW AN EASTWARD MOVEMENT OF THE D3/MON SHORTWAVE
TROUGH FROM CO/NM INTO THE CENTRAL PLAINS AND OK ON D4/TUE. PRIMARY
ATTENDANT SYNOPTIC LOW SHOULD CONSOLIDATE OVER CENTRAL NEB TUE
AFTERNOON...REACHING WESTERN IA BY 26/12Z...WHILE THE TRAILING LEE
TROUGH SPREADS EAST. MODELS SUGGEST THE GREATEST SHOWER/
THUNDERSTORM COVERAGE SHOULD OCCUR TUE NIGHT INTO EARLY WED MORNING
ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS TO IA/MO. THIS
WILL OCCUR WITHIN INCREASING LOW-LEVEL MOISTURE/WARM AIR ADVECTION
PER STRENGTHENING SOUTHWESTERLY LOW-LEVEL JET FROM TX PANHANDLE TO
EASTERN KS/IA. WEAK INSTABILITY WILL LIMIT THE COVERAGE OF STRONG
TO SEVERE STORMS...PRECLUDING THE INCLUSION OF A 15-PERCENT SEVERE
00Z ECMWF/GFS/UKMET ARE IN GENERAL AGREEMENT DURING THE FIRST HALF
OF D5/WED...WITH THE EASTWARD PROGRESSION OF THE D4 CENTRAL PLAINS
TROUGH ACROSS THE MS VALLEY...THOUGH DIFFER IN THE AMPLIFICATION OF
THIS TROUGH. THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE ALONG A WIND
SHIFT ADVANCING ACROSS MO/SOUTHERN IL...EASTERN OK...AR AND NORTH
TX. HOWEVER...UNCERTAINTY IN THE AMOUNT OF INSTABILITY AND
GENERALLY WEAK FORCING FOR ASCENT SHOULD LIMIT THE SEVERE-WEATHER
MODELS DIFFER WITH THE EVOLUTION OF THE MID- TO UPPER-LEVEL FLOW
PATTERN SUCH THAT THE FORECAST CONFIDENCE FOR ANY ORGANIZED
SEVERE-WEATHER THREAT REMAINS QUITE LOW.
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