SPC 0700Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1228 AM CST WED NOV 21 2012 VALID 221200Z - 231200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE UPPER-AIR PATTERN FCST THROUGH PERIOD...WITH REGARD TO BOTH NRN AND SRN STREAM FEATURES. SRN-STREAM SHORTWAVE TROUGH -- NOW APPARENT IN MOISTURE CHANNEL IMAGERY NEAR SW BAJA COAST -- IS FCST TO EJECT NEWD ACROSS NWRN MEX DAY-1. THIS FEATURE THEN SHOULD WEAKEN GRADUALLY BUT MAINTAIN SOME IDENTITY IN VORTICITY/HEIGHT FIELDS AS IT MOVES FROM W TX ACROSS N TX AND OK THROUGH 23/00Z...THEN ACCELERATE ENEWD OVER TN/KY BY END OF PERIOD IN ADVANCE OF AMPLIFYING NRN-STREAM TROUGH. LATTER FEATURE...NOW LOCATED OFFSHORE PAC NW...IS EXPECTED TO MOVE ACROSS NRN ROCKIES DAY-1...REACHING NRN HIGH PLAINS BY START OF PERIOD. TROUGH THEN SHOULD MOVE EWD ACROSS DAKOTAS AND UPPER MS VALLEY...REACHING LS....UPPER MI...WI AND IA BY 23/12Z. SOME DISCREPANCIES EXIST AMONG OPERATIONAL AND SREF MODELS REGARDING AMPLITUDE OF THIS SYSTEM...BUT THEY ARE GENERALLY IN STG AGREEMENT WITH RESPECT TO ITS TIMING THROUGH DAY-2. AT SFC...COLD FRONT PRECEDING NRN-STREAM TROUGH IS EXPECTED TO BEGIN DAY-2 INVOF NERN MN...NERN NEB...AND W-CENTRAL/SWRN KS. BY 23/00Z...FRONT SHOULD MOVE TO NEAR ERN LS...IA/IL BORDER...SWRN MO...CENTRAL OK...AND SERN NM...WITH WEAK FRONTAL-WAVE LOW POSSIBLE OVER NW TX. BY 23/12Z...EXPECT FRONT TO REACH SRN ONT...OH...WRN PORTIONS KY/TN...SRN AR...CENTRAL TX AND CHIHUAHUA. ...TRANS/PECOS AND SRN HIGH PLAINS TO PORTIONS MO... SCATTERED CONVECTION...INCLUDING ISOLATED TO WIDELY SCATTERED TSTMS...ARE POSSIBLE FROM ROUGHLY MID-AFTN ONWARD IN THIS CORRIDOR. ALTHOUGH IT IS TOO SOON TO GET MORE SPECIFIC ABOUT CONVECTIVE INITIATION TIMING/MODE...PRIND MOST PROBABLE SCENARIO IS FOR HIGH-BASED AND PERHAPS ELEVATED CONVECTION TO DEVELOP OVER MO PORTION OF THIS CORRIDOR INVOF FRONT...FOLLOWED BY SFC-BASED ACTIVITY SWWD OVER PORTIONS OK AND W-CENTRAL/SW TX. FCST SOUNDINGS SHOW WEAK MIDLEVEL LAPSE RATES...BUT ALSO WEAK MLCINH OVER MUCH OF FRONTAL CORRIDOR DURING AFTN/EVENING. MOISTURE RETURN WILL BE INCOMPLETE AND WEAK...WITH 50S F SFC DEW POINTS MOST COMMON IN NARROW CORRIDOR AHEAD OF FRONT OVER OK/W TX. MODIFIED FCST SOUNDINGS INDICATE AFTERNOON/PREFRONTAL MLCAPE RANGING FROM AROUND 800 J/KG OVER PERMIAN BASIN/LOWER PECOS RIVER AREA TO LESS THAN 200 J/KG INVOF OK/MO BORDER...ALONG WITH WEAK DEEP-LAYER SHEAR THROUGHOUT. SVR POTENTIAL ACCORDINGLY SHOULD BE MINIMAL. OVERNIGHT TSTMS MAY OCCUR OVER N-CENTRAL THROUGH SW TX. SUCH CONVECTION PRIMARY WOULD BE ELEVATED AND N OF SFC FRONT...IN ZONE OF BAROCLINICALLY FORCED ASCENT OF MRGLLY MOIST AIR TO LFC. ..EDWARDS.. 11/21/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_0700.html
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