(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 010840
SPC AC 010840
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0340 AM CDT FRI JUL 01 2016
VALID 041200Z - 091200Z
WHILE GFS AND ECMWF OUTPUT SHOWS LARGE-SCALE/GENERAL SIMILARITY
THROUGH ROUGHLY DAY 6-7...DIFFERENCES ARE EVIDENT EVEN EARLY ON WITH
THE DETAILS IN TERMS OF TIMING AND LOCATION OF MORE SUBTLE FEATURES
/THOSE LIKELY TO BE ASSOCIATED WITH DAILY CONVECTIVE EPISODES/. THE
LATEST ECMWF ENSEMBLE MEAN FIELDS ALOFT BEAR THIS OUT AS WELL...WITH
A RELATIVELY FLAT/ZONAL H5 PATTERN THROUGH THE PERIOD SUGGESTIVE OF
MEMBER-TO-MEMBER OFFSETS IN LOCATION OF SHORT-WAVE RIDGES AND
IN GENERAL...HINTS THAT SOME SEVERE RISK WILL RESIDE ACROSS THE
CENTRAL APPALACHIANS VICINITY DAY 4 EXIST WITHIN BOTH THE ECMWF AND
GFS...AND POSSIBLY WWD INTO THE OH AND TN VALLEYS. DETAILS THOUGH
REMAIN QUITE DIFFICULT TO DISCERN...DUE TO AFOREMENTIONED LACK OF
PREDICTABILITY OF SMALLER-SCALE RIPPLES IN THE FLOW FIELD.
FOCUS FOR SEVERE RISK SHOULD GENERALLY SHIFT NWWD TOWARD THE NRN
PLAINS/UPPER MS VALLEY AREA/UPPER GREAT LAKES REGION IN THE DAYS 5-6
TIME FRAME...WITH A SURFACE FRONT PROGGED TO SHIFT W-E ACROSS THIS
REGION. AGAIN HOWEVER...UNCERTAINTY IN TIMING/LOCATION OF FEATURES
PRECLUDES HIGHLIGHTING OF SPECIFIC RISK AREAS.
WITH MORE SUBSTANTIAL MODEL DEVIATIONS INTO THE LATTER PORTION OF
THE PERIOD -- EVEN WITH LARGER-SCALE FEATURES...AN OVERALL LACK OF
CERTAINTY/CONFIDENCE WITH RESPECT TO LOCATING AREAS OF GREATER
SEVERE POTENTIAL DURING THE ENTIRE PERIOD SUGGESTS MAINTENANCE OF
LOW-PREDICTABILITY WORDING IN THE FORECAST AT THIS TIME.
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