SWODY2
SPC AC 191730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT MON OCT 19 2009
VALID 201200Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LOW-AMPLITUDE LARGE-SCALE PATTERN EVIDENT ACROSS CONUS...WITH SERIES
OF PROGRESSIVE SHORTWAVES EXPECTED TO DOMINATE CONVECTIVE POTENTIAL
NEXT COUPLE DAYS. PRIMARY SHORTWAVE TROUGH -- NOW EVIDENT IN
MOISTURE CHANNEL IMAGERY MOVING ASHORE NRN CA -- IS FCST TO DIG SEWD
ACROSS WRN NV BY 20/12Z...THEN PIVOT EWD ACROSS 4-CORNERS REGION AND
SRN ROCKIES. ALTHOUGH ONLY PRESENT IN MINORITY OF SREF MEMBERS AND
OPERATIONAL SPECTRAL/WRF...PRESENCE OF EMBEDDED/CLOSED 500 MB LOW
WITH THIS FEATURE IS REASONABLE THROUGH PERIOD...GIVEN CURRENT
SATELLITE TRENDS AND ANALYZED 12Z HEIGHT CHANGE PATTERN.
AT SFC...CYCLONES ARE FCST AT BEGINNING OF PERIOD OVER UT AND INVOF
KS/CO BORDER. FORMER SHOULD WEAKEN AS COMBINED
LEE-SIDE/FRONTAL-WAVE LOW INTENSIFIES NEARLY IN PLACE E OF
ROCKIES...YIELDING PRONOUNCED SFC LOW OVER SWRN KS/SERN CO BY
21/00Z. COLD FRONT WILL MOVE EWD ACROSS AZ/NM DURING DAY THEN LINK
WITH LEE-SIDE LOW BY 21/06Z. FRONTAL ZONE FARTHER NE ACROSS ERN NEB
AND SRN MN SHOULD REMAIN QUASISTATIONARY THROUGH 21/00Z...WITH
SECONDARY/FRONTAL-WAVE LOW DEVELOPMENT POSSIBLE AFTER DARK OVER IA.
AS UPPER TROUGH APCHS...COLD FRONT WILL MOVE SEWD ACROSS CENTRAL/SRN
HIGH PLAINS.
...SERN AZ TO SRN HIGH PLAINS...
WIDELY SCATTERED TSTMS MAY DEVELOP LATE MORNING THROUGH
MID-AFTERNOON AND MOVE EWD ACROSS THIS REGION. FAVORABLY STG
VERTICAL WIND PROFILES AND DEEP-LAYER SHEAR EACH WILL SHIFT EWD
ACROSS THIS REGION AHEAD OF COLD FRONT...WITH 500 MB WINDS AOA 45 KT
AS FAR S AS DUG BY 20/18Z. GPS PW DATA CURRENTLY INDICATES .75-1
INCH PW ACROSS ELP-TUS CORRIDOR...AND OVER AN INCH FARTHER S OVER
SONORA. SUCH MOISTURE SHOULD BE MAINTAINED AND ADVECTED NEWD IN LOW
LEVEL WAA REGIME AHEAD OF MIDLEVEL WAVE. THIS MOISTURE WITH
DIABATIC SFC HEATING SHOULD BE AT LEAST MRGLLY SUFFICIENT TO
OVERCOME RELATIVELY WEAK MIDLEVEL LAPSE RATES...FOR DIURNAL MLCAPE
POTENTIALLY 250-500 J/KG. STRENGTH OF AMBIENT FLOW SUGGESTS
POTENTIAL FOR SOME DOWNWARD MOMENTUM TRANSFER IN DOWNDRAFTS AND
POSSIBILITY OF ISOLATED DAMAGING GUSTS. MID-LATE AFTERNOON
CONVECTION DEVELOPING ACROSS SERN NM AND W TX MAY BE RATHER
HIGH-BASED ATOP WELL-MIXED BOUNDARY LAYER...ALSO SUPPORTING STG TO
MRGL SVR GUSTS.
WEAKENING LOW LEVEL MOISTURE AND INCREASING CINH WITH EWD EXTENT
WILL LIMIT POTENTIAL FOR DIURNAL CONVECTION FARTHER E ACROSS
CENTRAL/SRN HIGH PLAINS FROM WRN KS TO OK/TX PANHANDLES AND
W-CENTRAL TX. DEEP-LAYER WIND PROFILES AND LOW-LEVEL MOISTURE WILL
STRENGTHEN WITH TIME AFTER DARK...AS RIBBON OF PARTIALLY MODIFIED
RETURN-FLOW AIR ADVECTS NWD AND NNEWD FROM RIO GRANDE/LOWER PECOS
VALLEYS. STRENGTHENING DEEP-LAYER SHEAR...AND STEEPENING LAPSE
RATES ATOP ELEVATED/LOW-LEVEL WAA REGIME...MAY SUPPORT POTENTIAL FOR
ISOLATED HAIL OR STG GUSTS WITH NOCTURNAL TSTMS FROM TRANS-PECOS
REGION TO PANHANDLES. CONVECTION WILL BE INCREASINGLY ELEVATED WITH
MORE LIMITED MUCAPE NEWD ACROSS WRN/SRN KS.
LACK OF MORE ROBUST WARM-SECTOR MOISTURE PRECLUDES CATEGORICAL
OUTLOOK ATTM.
..EDWARDS.. 10/19/2009
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