Monday, October 20, 2008

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201955
SWODY1
SPC AC 201952

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0252 PM CDT MON OCT 20 2008

VALID 202000Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
PROGRESSIVE UPPER AIR PATTERN FCST TO CONTINUE THROUGH REMAINDER
PERIOD ACROSS CONUS...FEATURING STG SHORTWAVE TROUGHS INITIALLY
EVIDENT OVER COASTAL PACIFIC NW AND OVER UPPER MS VALLEY/LS REGION.
ERN TROUGH SHOULD DIG ESEWD ACROSS UPPER GREAT LAKES AND ADJOINING
PORTIONS ONT/WI/MI. ASSOCIATED SFC COLD FRONT -- ANALYZED AT 18Z
FROM LH SWWD ACROSS LOWER MI...CENTRAL IL...SRN MO...SRN
OK...W-CENTRAL TX...IS DECELERATING ACROSS W TX AND LIKEWISE SHOULD
STALL OVERNIGHT ACROSS RED RIVER REGION.

MEANWHILE...PACIFIC NW TROUGH WILL PENETRATE FURTHER INLAND OVER
SWRN CANADA AND NRN ROCKIES...PRECEDED BY STRENGTHENING LOW LEVEL
COLD FRONT. SRN STREAM TROUGH -- EVIDENT IN MOISTURE CHANNEL
IMAGERY OVER WRN GREAT BASIN REGION -- IS EXPECTED TO MOVE EWD
ACROSS 4-CORNERS REGION INTO CENTRAL/SRN ROCKIES.

...CENTRAL/SRN ROCKIES AND ADJOINING HIGH PLAINS...
WIDELY SCATTERED TSTMS ALREADY HAVE DEVELOPED ACROSS WIDE SWATH FROM
S-CENTRAL NM NWWD ACROSS SWRN CO AND CENTRAL UT. DIABATIC SFC
HEATING OF TERRAIN W OF FRONT RANGE AND SANGRE DE CRISTOS...WITH AT
LEAST MRGL SFC MOISTURE...IS EXPECTED TO CONTRIBUTE TO ADDITIONAL
CONVECTIVE FORMATION OVER THIS REGION FOR ANOTHER 2-3 HOURS.
MUCAPES SHOULD RISE INTO 500-700 J/KG RANGE IN POCKETS REGULATED
LARGELY BY TERRAIN W OF ERN RANGES...AND BY EROSION OR ABSENCE OF
EARLIER CLOUD COVER OVER CENTRAL/SRN HIGH PLAINS. VERTICAL SHEAR
PROFILES ARE FAVORABLE FOR SVR ACROSS BROAD AREA...WITH 0-6 KM
VALUES COMMONLY 50-70 KT. HOWEVER...POTENTIAL WILL BE MITIGATED BY
LIMITED INSTABILITY AND RELATED CONCERNS ABOUT UPDRAFT
VIGOR/LONGEVITY IN FACE OF SUCH STG SHEAR. ATTM...SVR POTENTIAL
DOES NOT APPEAR TO BE SUFFICIENTLY FOCUSED TO REINTRODUCE AOA
5-PERCENT PROBABILITIES.

SCATTERED TO WIDELY SCATTERED TSTMS SHOULD DEVELOP DURING 06Z-12Z
TIME FRAME OVER PORTIONS SRN/CENTRAL HIGH PLAINS...BETWEEN NERN NM
AND N-CENTRAL KS. LATEST OPERATIONAL PROGS AND SREF GUIDANCE
INDICATE ELEVATED INITIATION MAY OCCUR ALMOST ANYWHERE IN THAT
SWATH...WITHIN BROAD/NEBULOUS ZONE OF LOW LEVEL WAA AND GRADUAL
MOISTENING ABOVE SFC. AGAIN WITH THIS REGIME...SVR OUTLOOK IS
PRECLUDED BY WEAKNESS OF INSTABILITY AND MOISTURE...AS WELL AS BY
LACK OF MORE COHERENT FOCI FOR INITIATION AND TSTM MAINTENANCE.

..EDWARDS.. 10/20/2008

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