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| Day 4-8 Severe Weather Outlook Issued on Apr 24, 2011 |
| Updated: Sun Apr 24 08:51:03 UTC 2011 |
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| D4 | Wed, Apr 27, 2011 - Thu, Apr 28, 2011 |
D7 | Sat, Apr 30, 2011 - Sun, May 01, 2011 |
| D5 | Thu, Apr 28, 2011 - Fri, Apr 29, 2011 |
D8 | Sun, May 01, 2011 - Mon, May 02, 2011 |
| D6 | Fri, Apr 29, 2011 - Sat, Apr 30, 2011 |
(All days are valid from 12 UTC - 12 UTC) |
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Note: A severe weather area depicted in the Day 4-8 period indicates a 30% or higher probability for severe thunderstorms within 25 miles of any point.
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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.
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POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears highly unlikely during the entire period (e.g. less than a 30% probability for a regional severe storm area across the CONUS through the entire Day 4-8 period).
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ZCZC SPCSWOD48 ALL
ACUS48 KWNS 240850
SPC AC 240850
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0350 AM CDT SUN APR 24 2011
VALID 271200Z - 021200Z
...DISCUSSION...
WIDESPREAD CONVECTIVE/SEVERE WEATHER EVENT -- ONGOING FROM THE DAY 3
/TUE. 4-26/ PERIOD -- IS LIKELY TO CONTINUE SPREADING EWD ACROSS THE
OH/TN VALLEYS AND GULF COAST STATES DAY 4 /WED. 4-27/...AS
MEDIUM-RANGE MODELS BOTH FORECAST EWD PROGRESSION OF THE LARGE
CENTRAL U.S. TROUGH. AS THE COLD FRONT SHIFTS EWD TOWARD THE
APPALACHIANS THROUGH THE AFTERNOON AND EVENING...PRE-FRONTAL WARM
SECTOR FEATURING MODERATE INSTABILITY AND STRONG DEEP-LAYER SHEAR
WILL SUPPORT CONTINUATION/REDEVELOPMENT OF SEVERE STORMS INTO THE
AFTERNOON AND EVENING. POTENTIAL FOR SUBSTANTIAL SEVERE WEATHER --
INCLUDING HAIL/WIND AND ISOLATED TORNADOES -- SUPPORTS CONTINUATION
OF A LARGE SEVERE WEATHER THREAT AREA FOR DAY 4.
MODEL TIMING WITH RESPECT TO THE SURFACE FRONT AND ASSOCIATED UPPER
TROUGH BEGINS TO DIFFER MORE SUBSTANTIALLY DAY 5 /THU. 4-28/...THUS
CASTING SOME UNCERTAINTY WITH RESPECT TO LOCATION AND DEGREE OF
THREAT E OF THE APPALACHIANS DAY 5. THEREFORE...WHILE POTENTIALLY
SEVERE CONVECTION WILL LIKELY SPREAD ACROSS THE ATLANTIC COAST
STATES SOMEWHERE BETWEEN LATE IN THE DAY 4 PERIOD AND THE AFTERNOON
AND EVENING OF DAY 5...WILL NOT HIGHLIGHT A SPECIFIC THREAT AREA
THIS FORECAST.
WITH THE FRONT EXPECTED TO HAVE SWEPT OFFSHORE BY THE START OF DAY 6
/FRI. 4-29/...FOCUS SHIFTS WWD AS THE NEXT SYSTEM SHIFTS ACROSS/OUT
OF THE ROCKIES. MODELS ARE IN MORE SUBSTANTIAL DISAGREEMENT WITH
THE EVOLUTION AND PROGRESSION OF THIS FEATURE...AND THUS WILL NOT
HIGHLIGHT ANY LONGER-RANGE THREAT AREAS THIS FORECAST.
..GOSS.. 04/24/2011
CLICK TO GET WUUS48 PTSD48 PRODUCT
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