SWODY1
SPC AC 280558
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT SAT APR 28 2007
VALID 281200Z - 291200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
A BROAD UPPER RIDGE IN THE WRN CONUS AND A BROAD UPPER TROUGH OVER
THE ERN CONUS WILL BE THE PREDOMINANT UPPER LEVEL FEATURES THROUGH
THE PERIOD. TO THE SOUTH OF THE BROAD UPPER RIDGE...A CUT-OFF UPPER
LOW OVER BAJA CA WILL MOVE SLOWLY NEWD INTO SONORA MX. SUFFICIENT
INSTABILITY AND INCREASING LOW-MID LEVEL SHEAR WILL EXIST OVER
PORTIONS OF SWRN TX...SRN NM AND SERN AZ TO SUPPORT A LOW END SVR
THREAT IN ADVANCE OF THIS SYSTEM. FURTHER EAST...A SUBTLE MID LEVEL
SHORTWAVE TROUGH WILL MOVE SEWD THROUGH THE BROAD ERN TROUGH. STEEP
MID LEVEL LAPSE RATES AND SUFFICIENT LOW LEVEL MOISTURE/INSTABILITY
AND SFC CONVERGENCE WILL EXIST TO SUPPORT A LOW PROB MARGINAL SVR
HAIL THREAT WITH TSTMS THAT DEVELOP OVER PORTIONS OF THE OHIO
VALLEY/MIDWEST.
..SWRN TX...SRN NM AND SERN AZ...
THE MID LEVEL GRADIENT WILL INCREASE OVER THE AREA TODAY AS AN UPPER
LOW CENTERED OVER BAJA CA EARLY IN THE DAY SLOWLY LIFTS NEWD INTO
WRN SONORA MX...AND UPPER RIDGING REMAINS NEARLY STATIONARY CENTERED
OVER THE GREAT BASIN. EARLY MORNING SFC ANALYSIS SHOWS AN AXIS OF
LOW LEVEL MOISTURE /DEWPTS IN THE 55-60 DEG F RANGE/ EXTENDING NWWD
UP THE RIO GRANDE/UPPER PECOS RIVER VALLEYS. THIS MOISTURE WILL
ADVECT WWD THROUGH THE PERIOD AS SFC HIGH PRESSURE BUILDS SWD
THROUGH THE SRN PLAINS AND SFC LOW PRESSURE REMAINS OVER WRN AZ. AS
A RESULT OF THE ELY LOW LEVEL WINDS...UPSLOPE FLOW WILL INCREASE
OVER THE HIGHER TERRAIN OF NRN SONORA/CHIHUAHUA MX. ALONG WITH THE
SUPPORT OF AN UPPER DIFFLUENT FLOW PATTERN... CONVECTION IS EXPECTED
TO DEVELOP AND MOVE EWD OVER SWRN TX...NWD OVER SRN NM AND WNWWD
OVER SERN AZ. GIVEN MODERATE INSTABILITY /MUCAPES FROM 1000-2000 J/
AND MODERATE DEEP LAYER SHEAR OVER SWRN TX SUPPORITING SOME
POTENTIAL FOR ISOLATED FEW SUPERCELLS WITH A MARGINAL SVR WIND/HAIL
THREAT. FURTHER WEST...ALTHOUGH WEAKER INSTABILITY WILL EXIST
/MUCAPES FROM 500-1000 J/KG/ OVER SWRN NM/SERN AZ...A DEEPLY MIXED
BOUNDARY LAYER /DCAPES FROM 1000-1300 J/KG/ BENEATH 20-25 KT OF
ESELY MID LEVEL FLOW WILL SUPPORT A MARGINAL SVR WIND THREAT WITH
CONVECTION THAT DEVELOPS OVER THE HIGHER TERRAIN AND ORGANIZES INTO
A LINEAR MODE.
..FAR ERN IL...IN...WRN OH/NRN KY...
A SHORTWAVE TROUGH WILL MOVE SEWD FROM THE ERN GREAT LAKES REGION
INTO THE OHIO VALLEY/SRN GREAT LAKES DURING THE DAY. THE 28/00Z
SOUNDING FROM INL INDICATED STEEP MID LEVEL LAPSE RATES /AROUND 7.5
DEG C/KM/ ASSOCIATED WITH THIS WAVE. AHEAD OF AN ASSOCIATED SFC
TROUGH...LOW LEVEL MOISTURE WILL INCREASE TO AROUND 50 DEG F BY THE
EARLY AFTERNOON. AS SFC TEMPERATURES WARM INTO THE LOWER
70S...SBCAPES SHOULD RISE TO BETWEEN 750-1000 J/KG. GIVEN MODERATE
DEEP LAYER SHEAR PROFILES UNDER /35-40 KTS/...ISOLATED ROTATING
STORMS ARE EXPECTED TO DEVELOP WITH THE POTENTIAL FOR MARGINALLY SVR
HAIL.
..NRN ROCKIES/NRN HIGH PLAINS..
AS AN UPPER TROUGH SLOWLY BREAKS DOWN THE UPPER RIDGE...MID LEVEL
FLOW WILL INCREASE OVER THE REGION. IN ADDITION...FRONTOGENETIC
FORCING AND A RIBBON OF MID/HIGH LEVEL MOISTURE WILL SUPPORT
INCREASING INSTABILITY SUPPORTIVE OF A FEW TSTMS. DESPITE A DEEPLY
MIXED ENVIRONMENT...LACK THE LACK OF GREATER INSTABILITY /SBCAPES
AROUND 250 J/KG/ WILL PRECLUDE THE INCLUSION OF A 5 PERCENT WIND
PROBABILITY.
.CROSBIE.. 04/28/2007
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