SWODY1
SPC AC 310550
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT TUE JUL 31 2007
VALID 311200Z - 011200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
MAIN BELT OF WESTERLIES WILL EXIST N OF THE INTERNATIONAL BORDER
WITH PRIMARY FEATURE OF INTEREST BEING STRONG SHORT WAVE TROUGH
WHICH WILL TRANSLATE EWD THROUGH THE CANADIAN PRAIRIES. SRN FRINGE
OF HEIGHT FALLS ASSOCIATED WITH THIS SYSTEM WILL BRUSH THE NRN
PLAINS...EFFECTIVELY FLATTENING UPPER RIDGE OVER THE UPPER GREAT
LAKES.
IN THE LOW LEVELS...COLD FRONT ATTENDANT TO THE CANADIAN SYSTEM WILL
SHIFT EWD THROUGH THE NRN HIGH PLAINS INTO THE WRN DAKOTAS BY THIS
EVENING WITH TRAILING PART OF BOUNDARY STRETCHING WWD INTO THE GREAT
BASIN. ELSEWHERE...REMNANT FRONTAL ZONE WILL PERSIST FROM SRN
GA/NRN FL WWD ALONG THE GULF COAST AND THEN NWWD WHERE IT MERGES
WITH A LEE TROUGH OVER THE CNTRL HIGH PLAINS.
..DAKOTAS INTO NRN INTERMOUNTAIN REGION...
A HOT AND DEEPLY MIXED BOUNDARY LAYER IS FORECAST TO DEVELOP AHEAD
OF SURFACE FRONT TODAY WITH TEMPERATURES WARMING THROUGH THE 90S
OVER ERN MT INTO THE WRN DAKOTAS. THIS DIABATIC HEATING COUPLED
WITH DEWPOINTS IN THE 50S TO PERHAPS LOWER 60S WILL RESULT IN THE
DEVELOPMENT OF A MODERATELY UNSTABLE AIR MASS WITH MLCAPES OF
1000-2000 J/KG. FORECAST SOUNDINGS SUGGEST THAT A CAP MAY LIMIT
DIURNAL CONVECTIVE DEVELOPMENT /DESPITE THE WARM BOUNDARY LAYER
CONDITIONS/ OWING TO EWD ADVECTION OF AN EML OFF THE NRN ROCKIES.
HOWEVER...SHOULD ISOLATED STORMS DEVELOP...A THREAT OF MAINLY
DAMAGING WIND GUSTS WILL EXIST OWING TO THE STRONG EVAPORATIONAL
COOLING POTENTIAL WITHIN SUB-CLOUD LAYER.
ADDITIONAL...ISOLATED STORMS ARE LIKELY TO DEVELOP ALONG TRAILING
PORTION OF FRONT OR IN IMMEDIATE POST-FRONTAL AIR MASS OVER SWRN MT
INTO NWRN WY WHERE OROGRAPHIC FORCING WILL CONTRIBUTE TO STORM
INITIATION. VERTICAL SHEAR WILL NOT BE PARTICULARLY STRONG...THOUGH
THE PRESENCE OF RELATIVELY STEEP LAPSE RATES AND MLCAPES OF 500-1000
J/KG INDICATE SOME THREAT OF SOME HAIL AND/OR LOCALLY GUSTY WINDS.
..SERN ATLANTIC COAST INTO THE SRN PLAINS...
A MOIST LOW-LEVEL AIR MASS WILL BE MAINTAINED ALONG STALLED FRONTAL
BOUNDARY WITH DEWPOINTS IN THE UPPER 60S TO LOW/MID 70S COMBINING
WITH DAYTIME HEATING TO SUPPORT MLCAPES OF 1500-3000 J/KG. SIMILAR
TO PREVIOUS DAYS...TSTMS WILL BECOME INCREASINGLY NUMEROUS THROUGH
THE AFTERNOON...FOCUSED ALONG PRIMARY FRONT AS WELL AS ANY RESIDUAL
OUTFLOW BOUNDARIES. VERTICAL SHEAR WILL REMAIN QUITE WEAK WITH MOST
STORMS REMAINING PULSE OR MULTICELL IN NATURE WITH THE MAIN THREAT
BEING WET MICROBURSTS.
..AZ...
E-W ORIENTED MID-LEVEL SHEAR ZONE OVER NRN MEXICO WILL BECOME
INCREASINGLY FRAGMENTED THROUGH THE PERIOD WITH WEAK IMPULSES SLOWLY
TRANSLATING WWD ACROSS THE REGION. ENVIRONMENT WILL REMAIN
RELATIVELY MOIST OWING TO PRESENCE OF DEEP MOIST PLUME...THOUGH THIS
WILL TEND TO LIMIT THE STEEPNESS OF MID-LEVEL LAPSE RATES AND
RESULTANT INSTABILITY. STILL...SOME POTENTIAL FOR MAINLY STRONG
WIND GUSTS WILL EXIST WITH STRONGER STORMS OR STORM MERGERS...NAMELY
AS ACTIVITY MOVES INTO LOWER ELEVATION AND PROGRESSIVELY MORE
UNSTABLE AIR MASS.
.MEAD/LEVIT.. 07/31/2007
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