storm prediction center norman oakloma

Posted By: tornadoes2  Posted On: Jul 14th, 2013  Filed Under: Weather

Day 4-8 Severe Weather Outlook Issued on Jul 14, 2013
Updated: Sun Jul 14 08:57:03 UTC 2013
D4-8 D4 D5 D6 D7 D8
 Population  Cities/Towns  CWAs  Interstates  Counties  FEMA Regions
Day 4-8 Severe Weather Outlook. A depicted severe weather area indicates a 30% or higher probability for severe thunderstorms within 25 miles of a point.
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
D5 176,834 9,949,942 Minneapolis, MN…St. Paul, MN…Grand Rapids, MI…Green Bay, WI…Duluth, MN…
D6 167,371 36,031,373 Chicago, IL…Detroit, MI…Milwaukee, WI…Cleveland, OH…Toledo, OH…
D7 174,663 52,939,222 New York, NY…Philadelphia, PA…Boston, MA…Pittsburgh, PA…Newark, NJ…
D4 Wed, Jul 17, 2013 – Thu, Jul 18, 2013 D7 Sat, Jul 20, 2013 – Sun, Jul 21, 2013
D5 Thu, Jul 18, 2013 – Fri, Jul 19, 2013 D8 Sun, Jul 21, 2013 – Mon, Jul 22, 2013
D6 Fri, Jul 19, 2013 – Sat, Jul 20, 2013 (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 a 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 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).
 Forecast Discussion
   ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 140856
   SPC AC 140856

   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0356 AM CDT SUN JUL 14 2013

   VALID 171200Z - 221200Z

   ...DISCUSSION...
   MULTI-DAY SEVERE EVENT POSSIBLE D5 /THU JUL 18/ THROUGH D7 /SUN JUL
   20/

   MEDIUM RANGE GUIDANCE FROM THE GFS...ECMWF AND CMC GLOBAL MODELING
   SYSTEMS HAS BEEN CONSISTENT WITH THE LARGE SCALE PATTERN EVOLUTION
   DURING THE D4-8 PERIOD SHOWING DEVELOPMENT OF BROAD LONG WAVE TROUGH
   MOVING ACROSS SERN CANADA...THE GREAT LAKES AND NERN STATES.  AS
   THIS OCCURS A SURFACE LOW...INITIALLY OVER THE NRN PLAINS...WILL
   MOVE ENEWD ACROSS THE NRN GREAT LAKES AND SERN CANADA WHILE A
   TRAILING COLD FRONT EXTENDING SWWD FROM THE LOW ADVANCES SEWD ACROSS
   GREAT LAKES AND NERN STATES.  ALTHOUGH THE ECMWF DETERMINISTIC RUNS
   AND ENSEMBLE SYSTEMS HAVE EXHIBITED MORE RUN-TO-RUN CONTINUITY THAN
   THE GFS IN THE HANDLING OF THE SHORT WAVE FEATURES AND ASSOCIATED
   WIND FIELDS ASSOCIATED WITH THE LONG WAVE TROUGH...A SIMILAR LARGE
   SCALE SIGNAL FROM MULTIPLE MODELING SYSTEMS SUGGESTS PATTERN
   PREDICTABILITY IS RELATIVELY HIGH DURING THIS PERIOD IN THE REGION
   OF INTEREST.

   A VERY MOIST AND UNSTABLE AIR MASS IS LIKELY TO BE PRESENT OVER THE
   NRN PLAINS/UPPER MS VALLEY AND INTO THE NERN STATES ON D4-5 IN
   ADVANCE OF THE SURFACE LOW AND COLD FRONT.  THIS WILL INCREASE THE
   POTENTIAL FOR WIDESPREAD DAMAGING WIND GUSTS AND OCCASIONAL HAIL TO
   OCCUR WITH SEVERE STORMS ALONG AND AHEAD OF THE COLD FRONT. 
   ALTHOUGH PRIMARY THREAT AREAS MAY BE MODULATED BY EFFECTS OF PRIOR
   CONVECTION/OUTFLOW BOUNDARIES...OVERALL SYNOPTIC SCALE FORCING
   APPEARS SUFFICIENT TO DELINEATE REGIONS OF ENHANCED SEVERE POTENTIAL
   DURING THIS PERIOD.  

   D5 /THU JUL 18/...SEVERE STORM POTENTIAL IS EXPECTED TO INCREASE BY
   LATE AFTERNOON/EVENING OVER THE UPPER MS VALLEY ALONG/NORTH OF A
   WARM FRONT...WITH SEVERE STORMS POSSIBLY SPREADING EWD DURING THE
   OVERNIGHT HOURS TOWARD THE GREAT LAKES.  THIS WILL OCCUR AS THE
   SURFACE LOW MOVES EWD AND THE LOW LEVEL JET VEERS...STRENGTHENS AND
   BECOMES COUPLED WITH A STRONG WNWLY MID/UPPER LEVEL JET POSITIONED
   IMMEDIATELY TO ITS NORTH.  

   D6 /FRI JUL 19/...THE ELONGATED COUPLED LOW/MID LEVEL JET STRUCTURE
   IS EXPECTED TO PROGRESS EWD ACROSS THE GREAT LAKES AND INTO THE NERN
   STATES AS THE SURFACE LOW MOVES ACROSS SRN CANADA...AND THE COLD
   FRONT MOVES SEWD ACROSS THE GREAT LAKES.  SEVERE STORM POTENTIAL IS
   EXPECTED TO CONTINUE EWD/ESEWD ALONG AND AHEAD OF THE COLD FRONT
   FROM THE GREAT LAKES INTO NRN PARTS OF THE NERN STATES.

 

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