DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 190554
SWODY1
SPC AC 190552

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1152 PM CST MON JAN 18 2010

VALID 191200Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SRN CA/SW AZ...
AN UPPER-LEVEL TROUGH WILL MOVE NEWD AWAY FROM THE WEST COAST INTO
THE INTERMOUNTAIN WEST TODAY AS ANOTHER UPPER-LEVEL TROUGH
APPROACHES THE CA COAST. AHEAD OF THE UPPER-LEVEL TROUGH...A LARGE
AREA OF RAIN WITH EMBEDDED THUNDERSTORMS IS FORECAST TO MOVE INTO
THE LA BASIN LATE THIS AFTERNOON. THE EXIT REGION OF A POWERFUL
MID-LEVEL JET WILL AFFECT SRN CA MAINTAINING STRONG DEEP LAYER
SHEAR. FORECAST SOUNDINGS LATE THIS AFTERNOON FROM LOS ANGELES SEWD
SHOW 0-6 KM SHEAR VALUES IN THE 50 TO 60 KT RANGE WITH 0-3 KM SRH OF
350 TO 450 M2/S2. THIS SHEAR ENVIRONMENT COMBINED WITH CAPE
CONCENTRATED MOSTLY BELOW 700 MB COULD BE SUFFICIENT FOR LOW-TOPPED
ROTATING STORMS WITH A MARGINAL TORNADO THREAT. THIS THREAT WOULD BE
MOST LIKELY WITH CELLS THAT REMAIN DISCRETE ON THE SOUTH END OF THE
RAINBAND. STEEP MID-LEVEL LAPSE RATES WILL ALSO LIKELY BE CONDUCIVE
FOR HAIL.

FURTHER EAST ACROSS SOUTHWEST AZ...CONVECTION IS FORECAST TO DEVELOP
EARLY THIS EVENING AS LARGE-SCALE ASCENT INCREASES AHEAD OF THE
APPROACHING UPPER-LEVEL TROUGH. ETA-KF FORECAST SOUNDINGS IN SW AZ
SHOW STRONG DEEP LAYER SHEAR AND STEEP MID-LEVEL LAPSE RATES
SUGGESTING A MARGINAL HAIL THREAT COULD EXIST. INCREASING LOW-LEVEL
FLOW ASSOCIATED WITH A DEVELOPING LOW-LEVEL JET MAY ALSO SUPPORT A
MARGINAL THREAT FOR DAMAGING WIND GUSTS.

...NRN AR/SE MO/WRN TN...
AN UPPER-LEVEL TROUGH WILL MOVE NEWD ACROSS THE ARKLATEX TONIGHT AS
SUBSTANTIAL MOISTURE ADVECTION TAKES PLACE ACROSS THE LOWER MS
VALLEY. AS LARGE-SCALE ASCENT INCREASES LATE TONIGHT ACROSS THE
OZARKS...THUNDERSTORM DEVELOPMENT IS EXPECTED ON THE NOSE OF THE
LOW-LEVEL JET ACROSS NRN AR AND SE MO. THIS CONVECTION SHOULD SPREAD
EWD ACROSS THE MID-MS VALLEY TOWARD DAYBREAK. ETA-KF FORECASTS
SOUNDINGS AT 09Z TO 12Z IN THE MID-MS VALLEY SHOW MUCAPE IN THE 750
TO 1250 RANGE AND STEEP MID-LEVEL LAPSE RATES SUGGESTING A THREAT
FOR HAIL WILL EXIST. THE ELEVATED NATURE OF THE CONVECTION SHOULD
INHIBIT THE DAMAGING WIND GUST POTENTIAL AND THE STRONG CAPPING
INVERSION SHOULD LIMIT THE CONVECTIVE COVERAGE.

..BROYLES.. 01/19/2010

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