Skip Navigation Links weather.gov 
NOAA logo-Select to go to the NOAA homepage NOAA's National Weather Service   Select to go to the NWS homepage
Storm Prediction Center
navigation bar left  
  navigation bar end cap


 
USA.gov is the U.S. Government's official Web portal to all Federal, state and local government Web resources and services.

    Day 2 Outlook >
Dec 22, 2014 1300 UTC Day 1 Convective Outlook
Updated: Mon Dec 22 12:57:22 UTC 2014 (Print Version | 20141222 1300Z Day 1 shapefile | 20141222 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Tornado Wind Hail
 Population  Cities/Towns  CWAs  Interstates  Counties  ARTCC  FEMA Regions

 Forecast Discussion
   SPC AC 221257

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0657 AM CST MON DEC 22 2014

   VALID 221300Z - 231200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS PORTIONS LOWER MS
   VALLEY...CENTRAL GULF COAST...

   ...SUMMARY...
   ISOLATED SEVERE STORMS WILL BE POSSIBLE TODAY AND TONIGHT ACROSS
   PARTS OF THE LOWER MISSISSIPPI VALLEY AND GULF COAST REGIONS.

   ...SYNOPSIS...
   IN MID-UPPER LEVELS...BROADLY CYCLONIC PATTERN HAS TAKEN SHAPE
   ACROSS CENTRAL CONUS...AND WILL BE REINFORCED BY SEVERAL SHORTWAVE
   TROUGHS THROUGH REMAINDER OF PERIOD.  CLOSELY SPACED PERTURBATIONS
   NOW OVER ERN CO AND UPPER RED RIVER VALLEY REGION OF TX/OK ARE
   EXPECTED TO MERGE TODAY OVER OK...THEN PIVOT NEWD ACROSS MO/WRN IL
   TONIGHT.  PHASING OF COMBINED PERTURBATION WITH ANOTHER SHORTWAVE
   TROUGH MOVING SEWD FROM NRN HIGH PLAINS WILL CONTRIBUTE TO
   DEVELOPMENT OF CLOSED 500-MB CYCLONE TONIGHT OVER SERN NEB/SWRN
   IA/NWRN MO AREA.  MEANWHILE...UPSTREAM PERTURBATION AND RELATED
   SPEED MAX NOW OVER SRN BC ARE EXPECTED TO MOVE RAPIDLY SEWD TO NM
   AND W TX...APCHG BASE OF CYCLONIC-FLOW FIELD BY 12Z.  THESE
   PROCESSES WILL COMBINE TO TIGHTEN UPPER-LEVEL HEIGHT GRADIENT
   CONSIDERABLY E OF SYNOPTIC-SCALE TROUGH...LEADING TO EXPANSIVE AND
   INTENSIFYING FIELD OF 120-130-KT 250-MB SPEEDS OVER LOWER MS AND OH
   VALLEYS AROUND 12Z.

   AT SFC...11Z ANALYSIS SHOWED LOWS OVER NRN SD AND SWRN
   OK...CONNECTED BY FRONTAL ZONE THAT IN TURN EXTENDED WSWWD ACROSS NW
   TX AND WWD/NWWD ACROSS E-CENTRAL/NERN NM.  THESE LOWS SHOULD
   EFFECTIVELY CONSOLIDATE/REDEVELOP INTO SINGLE CYCLONE OVER MO BY
   00Z...AS CYCLONE ALOFT BEGINS TO TAKE SHAPE OVER CENTRAL PLAINS. 
   ASSOCIATED COLD FRONT SHOULD BE LOCATED OVER SRN MO...ARKLATEX
   REGION AND S-CENTRAL/SW TX AT 00Z.  SFC CYCLONE THEN SHOULD DEEPEN
   AND PIVOT NNEWD ACROSS ERN IA...WITH 12Z COLD-FRONTAL POSITION
   ROUGHLY ALONG AN EVV...JAN...GLS...COT LINE.

   MEANWHILE...WAVY FRONTAL ZONE EXTENDED NEWD AND SWWD FROM WEAK
   FRONTAL-WAVE LOW OFFSHORE SC...TO S-CENTRAL FL...THEN BECOMING WARM
   FRONT OVER NRN GULF WATERS S OF FL PANHANDLE...MS...AL...AND
   LA...AND OFFSHORE TX COAST.  THIS SHALLOW MARINE/WARM FRONT WILL
   DRIFT NWD THROUGH PERIOD...MOVING INLAND OVER PORTIONS SERN LA...SRN
   MS...SRN AL AND FL PANHANDLE.

   ...LOWER MS VALLEY...CENTRAL GULF COAST...
   AT LEAST WEAKLY FAVORABLE PARAMETER SPACES AND CONDITIONAL RISK OF
   DAMAGING GUSTS/TORNADOES WILL EXIST ACROSS THIS REGION THROUGHOUT
   LATTER 12-15 HOURS OF DAY-1 PERIOD -- FROM LATE AFTN ONWARD. 
   HOWEVER...LACK OF SUBSTANTIAL DEEP-LAYER LIFT AND WEAKNESS/ABSENCE
   OF LOW-LEVEL FOCI INDICATE VERY SPARSE COVERAGE OF SFC-BASED
   TSTMS...KEEPING UNCONDITIONAL PROBABILITIES MRGL ATTM.

   DEEP SHEAR WILL BE INCREASING OVER THIS REGION THROUGHOUT
   PERIOD...AS WILL LOW-LEVEL MOISTURE AND THETAE.  MOREOVER...SOMEWHAT
   ENLARGED/LOOPY LOW-LEVEL HODOGRAPHS LIKELY WILL DEVELOP INVOF WARM
   FRONT.  SUBTLE LARGE-SCALE ASCENT IS EXPECTED MAINLY N OF I-20 OVER
   CORRIDORS OF WEAK ELEVATED INSTABILITY...IN RELATION TO
   RIGHT-ENTRANCE REGION OF STRENGTHENING JET ALOFT...CONTRIBUTING TO
   ELEVATED THUNDER POTENTIAL OVER MID SOUTH AND OH VALLEY. 
   HOWEVER...ASCENT/DESTABILIZATION ALOFT RELATED TO MID-UPPER-LEVEL
   DCVA LIKELY WILL REMAIN DISPLACED FROM MOST FAVORABLE LOW-LEVEL
   THERMODYNAMIC FIELDS THIS PERIOD.  MOREOVER...SUPPORT FOR
   SUSTAINED/DEEP CONVECTION IS LACKING GIVEN...
   1. SHALLOW SLOPE OF WARM FRONT...
   2. LACK OF APPARENT/ADDITIONAL MESOSCALE FOCI TO AUGMENT LOW-LEVEL
   LIFT OVER DELTA/GULF COAST REGION...AND
   3. LIKELIHOOD OF WEAK MIDLEVEL LAPSE RATES AND STABLE LAYERS ALOFT
   PER 12Z LCH RAOB AND MULTIPLE MODEL-FCST SOUNDINGS.

   SFC DEW POINTS MID-UPPER 60S F MAY OFFSET THOSE POOR LAPSE RATES
   ENOUGH TO RESULT IN 500-1000 J/KG MLCAPE NEAR COAST AFTER
   DARK...THOUGH SOURCES FOR LOW-LEVEL FORCING APPEAR WEAK/UNCERTAIN
   ATTM.  SOME POTENTIAL ALSO EXISTS FOR SMALL SUPERCELLS TO FORM
   WITHIN RELATIVELY WEAKLY CAPPED AND HIGHEST-THETAE AIR MASS OVER
   GULF LATE IN PERIOD...MOVING EWD TOWARD COAST.  PRIND GREATEST
   CONCENTRATION OF ANY SUCH CONVECTION WILL REMAIN OFFSHORE THROUGH
   PERIOD...THOUGH ONE OR TWO SUCH TSTMS CANNOT BE RULED OUT TONIGHT
   OVER COASTAL AREAS FROM FL PANHANDLE WWD ACROSS SERN LA.

   ..EDWARDS/COHEN.. 12/22/2014

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z

        
Top/Latest Day 2 Outlook/Today's Outlooks/Forecast Products/Home
Weather Topics:
Watches, Mesoscale Discussions, Outlooks, Fire Weather, All Products, Contact Us

NOAA / National Weather Service
National Centers for Environmental Prediction
Storm Prediction Center
120 David L. Boren Blvd.
Norman, OK 73072 U.S.A.
spc.feedback@noaa.gov
Page last modified: December 22, 2014
Disclaimer
Information Quality
Help
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities