DAY1SVR: Day 1 Convective Outlook Corr 1

ACUS01 KWNS 192113
SWODY1
SPC AC 192110

DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0410 PM CDT SAT SEP 19 2009

VALID 192000Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

CORRECTED TO SWITCH ARROW ON 5 % WIND GRAPHIC

ONE CHANGE TO THE OUTLOOK IS TO ADD A 5 PERCENT WIND PROBABILITY
OVER ECNTRL AZ. THE 12Z FLAGSTAFF SOUNDING SHOWED ABOUT 1000 J/KG OF
MUCAPE WITH THE RUC ANALYZING A SMALL POCKET OF MODERATE INSTABILITY
/MLCAPE 1000-1500 J/KG/ NORTHEAST OF PHOENIX. THUNDERSTORMS ARE
INCREASING IN COVERAGE ALONG THE MOGOLLON RIM ON THE NRN EDGE OF THE
STRONGER INSTABILITY WHERE LOW-LEVEL LAPSE RATES ARE QUITE STEEP.
THIS MAY BE ENOUGH FOR A FEW MARGINALLY SEVERE DAMAGING WIND GUSTS
THIS AFTERNOON. ANOTHER MINOR CHANGE IS TO REMOVE THUNDER FROM THE
CNTRL OK AREA.

..BROYLES.. 09/19/2009

.PREV DISCUSSION... /ISSUED 1122 AM CDT SAT SEP 19 2009/

...SYNOPSIS...
A PRONOUNCED NRN STREAM MID LEVEL TROUGH IS MOVING EWD OVER WA/ORE
THIS MORNING...AND WILL CONTINUE EWD OVER THE NRN ROCKIES THROUGH
TONIGHT. INCREASING HEIGHT FALLS AND MEAN FLOW OVER THE PLAINS
/DOWNSTREAM FROM THE PAC NW TROUGH/ WILL BEGIN TO RESULT IN SLOW EWD
PROGRESSION OF THE SERIES OF VORTICITY CENTERS EMBEDDED IN THE
BROAD/WEAK LOW NOW CENTERED OVER KS/OK.

THE RICHEST MOISTURE PLUME AND MORE CONCENTRATED CONVECTION IS
EXPECTED TODAY OVER TN/AL IN ADVANCE OF DIFFUSE EMBEDDED MID LEVEL
TROUGH OVER THE LOWER MS VALLEY...WHICH WILL TEND TO SPREAD SLOWLY
NWD OVERNIGHT IN RESPONSE TO THE AMPLIFYING UPSTREAM FLOW REGIME
OVER THE ROCKIES AND CENTRAL/NRN PLAINS. ELSEWHERE...SCATTERED
/MAINLY DIURNAL/ THUNDERSTORMS WILL AGAIN OCCUR TODAY IN ASSOCIATION
WITH DAYTIME HEATING AND ENHANCED MOISTURE/ASCENT WITH THE DIFFUSE
EMBEDDED VORTICITY CENTERS OVER THE FOUR CORNERS STATES. SOME
PORTION OF THE LOW-MID LEVEL MOISTURE PLUME OVER THE NRN GREAT BASIN
/PER THE 12Z SLC SOUNDING/ WILL SPREAD NWD TO SW MT BY LATE
AFTERNOON ALONG THE COLD FRONT WITH THE PAC NW MID LEVEL TROUGH.
GUSTY WINDS WILL BE POSSIBLE WITH HIGH-BASED THUNDERSTORMS...BUT THE
SEVERE STORM THREAT APPEARS QUITE MARGINAL AT BEST.

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