Dec 29, 2010 1730 UTC Day 2 Convective Outlook
Updated: Wed Dec 29 17:29:58 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20101229 1730 UTC Day 2 Outlook Graphic
Probabilistic Graphic
20101229 1730 UTC Day Probabilitic Graphic
Probability Legend Image
   SPC AC 291728
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1128 AM CST WED DEC 29 2010
   
   VALID 301200Z - 311200Z
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   INCREASING AMPLITUDE FCST FOR UPPER AIR PATTERN THROUGH THIS
   PERIOD...AS SHORTWAVE TROUGH NOW OVER INTERIOR NWRN CONUS AND CA
   INTENSIFIES INTO MAJOR CYCLONE OVER INTERMOUNTAIN W.  BY END OF
   PERIOD...500-MB LOW SHOULD BE LOCATED OVER CENTRAL ROCKIES...WITH
   BROAD BELT OF SURROUNDING CYCLONIC FLOW FROM PAC NW TO AZ/NM AND
   OVER MUCH OF CENTRAL/SRN PLAINS.
   
   AT SFC...CYCLOGENESIS NOW UNDERWAY OVER NRN ROCKIES WILL MOVE SEWD
   AND BLEND INTO LEE TROUGHING NOW UNDERWAY OVER CENTRAL/NRN HIGH
   PLAINS...AS SFC COLD FRONT MOVES SEWD FROM MT ACROSS MUCH OF DAKOTAS
   AND WY.  RESULT BY 30/12Z SHOULD BE SFC LOW OVER S-CENTRAL OR
   E-CENTRAL NEB...WITH ARCTIC COLD FRONT SWWD ACROSS NERN CO.  WITHIN
   12 HOURS...THIS LOW SHOULD MOVE NEWD ACROSS ERN MN...WITH ARCTIC
   FRONT SWWD ACROSS WRN IA AND CENTRAL-SWRN KS.
   
   MEANWHILE SECONDARY CYCLONE SHOULD DEVELOP OVER SERN CO IN RESPONSE
   TO SHORTWAVE TROUGH PIVOTING THROUGH SRN PORTION OF MID-UPPER
   CYCLONE.  PAC COLD FRONT SHOULD TRAIL FROM SRN LOW SWD ACROSS NERN
   TX PANHANDLE AND EXTREME WRN NM BY 31/0Z.  SRN LOW IS FCST TO SHIFT
   GENERALLY EWD ALONG JUNCTION OF THESE COLD FRONTS OVER ERN KS.  BY
   END OF PERIOD...ARCTIC FRONT SHOULD EXTEND FROM KS LOW WWD INTO RTN
   AREA...WITH PAC FRONT ACROSS PORTIONS SRN OK...N-CENTRAL/NWRN TX AND
   EDWARDS PLATEAU REGION.
   
   ...SRN PLAINS TO AR...
   WRN OPEN GULF IS FCST TO CONTINUE MODIFYING...ESPECIALLY IN CORRIDOR
   FROM SRN BAY OF CAMPECHE NWD...JUST E OF SHELF WATERS WHERE SFC DEW
   POINTS ALREADY HAVE REACHED MID-60S F.  THIS WILL SUPPLY INCREASING
   MOISTURE WITH TIME TO OUTLOOK REGION.  SVR PROBABILITIES ARE
   ASSOCIATED WITH TWO REGIMES THAT SOMEWHAT OVERLAP SPATIALLY...BUT
   WITH OFFSET TIMING.  IN EITHER REGIME...UNCONDITIONAL SVR
   PROBABILITIES WOULD BE GREATER WITH ONLY SLGT INCREASES IN NEAR-SFC
   THETAE.
   
   1. EVENING TSTMS FROM PORTIONS ARKLATEX REGION NWD ACROSS ERN OK AND
   WRN AR...SHIFTING NEWD ACROSS AR OVERNIGHT IN ASSOCIATION WITH 45-55
   KT ERN BRANCH OF LLJ.  OPERATIONAL WRF/SPECTRAL AND MOST SREF
   MEMBERS ARE IN STG CONSENSUS WITH CONVECTION IN THIS REGIME DURING
   31/00Z-31/03Z TIME FRAME...ALTHOUGH ISOLATED TSTMS MAY DEVELOP
   BEFORE 00Z.  THIS IS REASONABLE...AS ONSET OF NOCTURNAL LLJ WILL
   STRENGTHEN ISENTROPIC ASCENT OF INCREASINGLY MOIST PARCELS TO LFC. 
   DEEP-LAYER SHEAR WILL BE FAVORABLE AMIDST 60-70 KT 500 MB
   FLOW...HOWEVER LACK OF MORE ROBUST MOISTURE ON THIS NERN FRINGE OF
   RETURN-FLOW PLUME WILL LIMIT BUOYANCY.  JUST A COUPLE OF DEGREES C
   HIGHER THETAE IN FCST SOUNDINGS WOULD RAISE CONCERNS FOR SFC-BASED
   SUPERCELLS...BUT FOR NOW MAIN THREATS APPEAR TO BE MRGL HAIL AND
   OCNL STG/DAMAGING GUSTS REACHING SFC.
   
   2. TSTMS ALSO MAY DEVELOP ALONG AND E OF SFC COLD FRONT DURING LAST
   FEW HOURS OF PERIOD...MOST PROBABLY OVER PORTIONS ERN/SRN OK WHERE
   CONTINUED MOISTURE TRANSPORT AND INTENSE LOW-LEVEL WAA/MOIST
   ADVECTION ALLOW CORRIDOR OF LATE-NIGHT DESTABILIZATION W OF AR
   CONVECTIVE PLUME.  WRN BRANCH OF LLJ SHOULD BUILD TO 45-55 KT
   BETWEEN 31/06Z-31/12Z AHEAD OF COLD FRONT...STRENGTHENING ISENTROPIC
   LIFT AND MOIST ADVECTION. ATTM...TIME SERIES OF FCST SOUNDINGS
   SUGGEST NEAR-SFC AIR MASS OVER THIS REGION WILL UNDERGO STG DIABATIC
   COOLING DURING EVENING...BEFORE STRONGEST PREFRONTAL MOIST ADVECTION
   OCCURS.  THIS WOULD LEAVE SUBSEQUENT MOISTURE-RICH RETURN FLOW
   SOMEWHAT ELEVATED ATOP RESULTING STABLE LAYER.  THEREFORE...SVR
   POTENTIAL IN THIS REGIME ALSO APPEARS TO BE IN FORM OF LARGE HAIL
   AND OCNL GUSTS THAT PENETRATE SHALLOW STABLE LAYER.
   
   ..EDWARDS.. 12/29/2010
   
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