SPC AC 161942
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0142 PM CST WED FEB 16 2011
VALID 162000Z - 171200Z
...NO SVR TSTM AREAS FORECAST...
CURRENT TRENDS CONTINUE TO SUPPORT EARLIER FORECAST ACROSS PORTIONS
OF THE INTERIOR GREAT BASIN AND OVER CA. FOR THIS REASON HAVE NOT
MADE MATERIAL CHANGES TO THE 1630Z OUTLOOK.
STEEP LOW LEVEL LAPSE RATES HAVE DEVELOPED ACROSS MUCH OF ERN NV/UT
AHEAD OF ADVANCING COLD FRONT. STRONG WINDS MAY MIX TO THE SURFACE
WITH ANY LONGER LIVED CONVECTIVE ELEMENTS OR FORCED LINE SEGMENTS
ALONG THE ADVANCING WIND SHIFT.
FARTHER WEST...BOUNDARY LAYER MOISTURE HAS DRIED SOMEWHAT ACROSS THE
SACRAMENTO VALLEY WITH SFC DEW POINTS NOW IN THE UPPER 30S-LOWER
40S. IT APPEARS THE GREATEST RISK WITH THE ONGOING SHOWERS/ISOLATED
THUNDERSTORMS WILL BE GUSTY WINDS AND PERHAPS MARGINALLY SEVERE
HAIL.
..DARROW.. 02/16/2011
.PREV DISCUSSION... /ISSUED 1018 AM CST WED FEB 16 2011/
...NORTHERN CA...
A LARGE UPPER TROUGH IS MOVING ASHORE OVER NORTHERN CA THIS
MORNING...WITH THE PRIMARY FRONTAL BAND MOVING ACROSS THE
NORTHERN/CENTRAL SIERRAS AND CENTRAL VALLEY. COLD MID LEVEL
TEMPERATURES AND STEEP LAPSE RATES ARE SPREADING INLAND AND WILL BE
IN PLACE ACROSS MUCH OF THE NORTHERN AND CENTRAL INTERIOR VALLEY BY
AFTERNOON. FORECAST SOUNDINGS IN THIS REGION SHOW FAVORABLE
THERMODYNAMIC PROFILES FOR A RISK OF HAIL IN STRONGER SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND EVENING. LOW LEVEL VERTICAL SHEAR
IS ALSO SUPPORTIVE FOR UPDRAFT ROTATION AND A BRIEF TORNADO...
ESPECIALLY IN TERRAIN-FAVORED AREAS.
...NV/UT...
THE PRIMARY FRONTAL BAND WILL PROGRESS EASTWARD ACROSS THE GREAT
BASIN THIS AFTERNOON AND BEGIN AFFECTING EASTERN NV AND MUCH OF UT
THIS EVENING. STRONG LARGE SCALE FORCING ALONG THE FRONT...COUPLED
WITH MARGINAL INSTABILITY WILL A BROKEN LINE OF SHOWERS AND ISOLATED
THUNDERSTORMS. A COMBINATION OF STEEP LOW LEVEL LAPSE
RATES...STRONG SOUTHWESTERLY ENVIRONMENTAL WINDS JUST ABOVE THE
SURFACE...AND SUFFICIENT CAPE WILL PROMOTE A RISK OF LOCALLY
GUSTY/DAMAGING WINDS WITH CONVECTION ALONG THE FRONT.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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