Dec 20, 2015 0830 UTC Day 3 Severe Thunderstorm Outlook
Updated: Sun Dec 20 08:30:28 UTC 2015 (20151220 0830Z Day 3 shapefile | 20151220 0830Z Day 3 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20151220 0830 UTC Day 3 Outlook Graphic
Day 3 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 235,667 29,610,269 Houston, TX...San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...
Probabilistic Graphic
20151220 0830 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
Day 3 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 236,424 29,745,285 Houston, TX...San Antonio, TX...Dallas, TX...Austin, TX...Fort Worth, TX...
   SPC AC 200830

   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0230 AM CST SUN DEC 20 2015

   VALID 221200Z - 231200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS MAINLY TUESDAY NIGHT ACROSS
   PARTS OF THE SOUTHEASTERN PLAINS...WESTERN AND CENTRAL GULF COAST
   REGION...

   ...SUMMARY...
   THUNDERSTORMS WILL IMPACT PORTIONS OF THE SOUTHEASTERN PLAINS...AND
   PORTIONS OF THE WESTERN INTO CENTRAL GULF COAST REGION...TUESDAY
   THROUGH TUESDAY NIGHT...WITH AT LEAST SOME RISK FOR SEVERE WEATHER.

   ...SYNOPSIS...
   MODELS SUGGEST UPPER TROUGH AMPLIFICATION WILL CONTINUE OVER THE
   INTERIOR U.S...MAINLY EAST OF THE CENTRAL/SOUTHERN ROCKIES THROUGH
   THE CENTRAL/SOUTHERN PLAINS...DOWNSTREAM OF A STRONG MID/UPPER JET
   WHICH MAY CONTINUE TO NOSE INLAND ACROSS THE PACIFIC COAST.  AT
   LEAST SOME PHASING WITH A SIGNIFICANT IMPULSE EMERGING FROM THE
   LOWER LATITUDE EASTERN PACIFIC IS POSSIBLE...AS THE LATTER FEATURE
   ACCELERATES NORTHEAST OF THE MEXICAN PLATEAU THROUGH THE WESTERN
   GULF OF MEXICO.  IN RESPONSE TO THESE DEVELOPMENTS...SECONDARY
   SURFACE CYCLOGENESIS IS FORECAST WITHIN LEE SURFACE TROUGHING...FROM
   THE HIGH PLAINS OF SOUTHEAST COLORADO THROUGH THE CENTRAL PLAINS. 
   AND CONSIDERABLE STRENGTHENING OF LOWER/MID TROPOSPHERIC WIND FIELDS
   ARE LIKELY LATE TUESDAY THROUGH TUESDAY NIGHT ACROSS THE SOUTHERN
   PLAINS THROUGH LOWER MISSISSIPPI VALLEY...WESTERN AND CENTRAL GULF
   COAST REGION.  THIS MAY INCLUDE AT LEAST ONE BRANCH OF STRENGTHENING
   SOUTHERLY 850 MB FLOW /TO 40-50+ KT/...FROM THE WESTERN GULF OF
   MEXICO THROUGH PORTIONS OF THE OZARK PLATEAU AND LOWER MISSISSIPPI
   VALLEY.

   ...SERN PLAINS THROUGH WRN AND CNTRL GULF COAST REGION...
   CONSIDERABLE THUNDERSTORM ACTIVITY MAY BE ONGOING EARLY TUESDAY NEAR
   OR PERHAPS OFFSHORE OF CENTRAL GULF COASTAL AREAS...AND LARGE-SCALE
   FORCING FOR ASCENT MAY MAINTAIN THIS ACTIVITY IN THE SAME GENERAL
   REGION THROUGH MUCH OF THE DAY.  AS THE MAIN SUBTROPICAL IMPULSE
   BEGINS IMPACTING THE CENTRAL GULF COAST REGION TUESDAY NIGHT...A
   FURTHER INCREASE IN CONVECTIVE COVERAGE AND INTENSITY ARE POSSIBLE
   IN THE PRESENCE OF STRENGTHENING SHEAR.  THERE SHOULD ALSO BE A
   TENDENCY FOR ACTIVITY TO ADVANCE NORTHWARD...EITHER INLAND OF THE
   CENTRAL GULF COAST...OR FROM THE NORTHERN GULF OF MEXICO INTO
   COASTAL AREAS.  SEVERE WEATHER POTENTIAL WILL GENERALLY BE
   DETERMINED BY THE EXTENT OF BOUNDARY LAYER DESTABILIZATION
   INLAND...WHICH MAY BE HAMPERED BY THE PRESENCE OF COASTAL CONVECTION
   THROUGH MUCH OF THE PERIOD...ACROSS LOUISIANA/MISSISSIPPI AND
   ALABAMA.

   MODELS SUGGEST THAT AT LEAST WEAK BOUNDARY LAYER DESTABILIZATION IS
   MORE CERTAIN WITHIN THE EVOLVING WARM SECTOR OF THE DEVELOPING
   SURFACE LOW...ACROSS MUCH OF EASTERN TEXAS THROUGH THE ARKLATEX
   REGION.  THE STRENGTH AND AREAL COVERAGE OF FORCING FOR ASCENT
   REMAIN A BIT UNCLEAR...BUT ITS POSSIBLE THAT MID-LEVEL FORCING WITH
   THE MID-LATITUDE WAVE COULD CONTRIBUTE TO INCREASING STORM
   DEVELOPMENT ACROSS AT LEAST PARTS OF NORTHEAST TEXAS AND THE
   ARKLATEX TUESDAY NIGHT.  THIS COULD COMMENCE PRIOR TO 23/06Z...BUT
   IT SEEMS MORE PROBABLE AFTER.  EVEN SO...THE ENVIRONMENT MAY BE
   CONDUCIVE TO ORGANIZED CONVECTION...INCLUDING SUPERCELLS.

   ..KERR.. 12/20/2015

   CLICK TO GET WUUS03 PTSDY3 PRODUCT

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z