SWODY1
SPC AC 310104
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0804 PM CDT WED JUL 30 2008
VALID 310100Z - 311200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OZARKS TO LOWER MO
VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS NRN PLAINS...
...SYNOPSIS...
UPPER LOW IS EVIDENT IN MOISTURE CHANNEL IMAGERY OVER ERN
ONT...MOVING EWD TOWARD WRN QUE...WITH SHORTWAVE TROUGH ANALYZED SWD
ACROSS WRN/CENTRAL PA. UPSTREAM...RIDGE IS ANALYZED FROM NRN MB
SSWWD ACROSS DAKOTAS TO ERN CO...WITH UPSTREAM TROUGH FROM WRN SASK
SSWWD ACROSS WRN/CENTRAL MT...WHICH IS FCST TO MOVE EWD ACROSS SASK
AND OVER WRN ND BY END OF PERIOD. OUTSIDE THESE
PERTURBATIONS...NEARLY ZONAL FLOW CHARACTERIZES NRN STREAM PATTERN.
HOWEVER...WELL-DEFINED TROUGH IS ANALYZED FARTHER S...DIAGONALLY
ACROSS MO OVER SERN OK...AND PORTIONS CENTRAL/SW TX. THIS TROUGH
SHOULD SWIVEL INTO MORE POSITIVELY TILTED ALIGNMENT THROUGH
REMAINDER PERIOD AS NRN PORTION MOVES E ACROSS ERN IL...AND TX
SEGMENT BECOMES QUASISTATIONARY.
AT SFC...COLD FRONT IS ANALYZED FROM LOW OVER ERN ONT...SWWD ACROSS
OH...SRN IL...SERN OK...FAR W TX. ALTHOUGH UPPER SUPPORT FOR SWD
MOTION OF FRONT IS DIMINISHING OVER SRN PLAINS...EFFECTIVE FRONTAL
ZONE SHOULD CONTINUE TO BE SHUNTED FARTHER S OVER W TX AND FROM
CENTRAL TX NEWD ACROSS OZARKS BY CONVECTIVE OUTFLOW PROCESSES FOR AT
LEAST A FEW MORE HOURS...BEFORE DECELERATING. REMAINDER FRONT
SHOULD MOVE SEWD/EWD SLOWLY OVER OH/IN/IL. COLD FRONT EXTENDS FROM
LOW OVER ERN MT...SWWD ACROSS S-CENTRAL/SWRN MT AS OF 23Z...AND
SHOULD MOVE EWD OVER WRN ND AND SEWD ACROSS PORTIONS WY...WHILE LOW
NOW DEVELOPING OVER S-CENTRAL/SWRN SD INTENSIFIES. WARM FRONT
SHOULD BECOME BETTER DEFINED E OF THAT LOW ACROSS ERN SD AND SRN MN.
...OH VALLEY TO SRN PLAINS...
GREATEST CONCENTRATION OF SVR POTENTIAL NEXT FEW HOURS WILL REMAIN
IN AND NEAR WW 776...WHERE VERY RICH LOW LEVEL MOISTURE...LEFT INVOF
FRONTAL ZONE...AND AT LEAST MRGL DEEP-LAYER SHEAR WILL SUPPORT
POTENTIAL FOR ORGANIZED MULTICELL AND SHORT-LIVED SUPERCELL
MORPHOLOGIES...ALONG WITH SHORT BOWING SEGMENTS. MODIFIED 00Z SGF
SOUNDING AND RUC SOUNDINGS INDICATE 1500-2500 J/KG MLCAPE THROUGH AT
LEAST 03Z. RAOB WAS ON WEAK SHEAR SIDE OF BOUNDARY...WITH 30-40 KT
EFFECTIVE SHEAR AND SIMILAR THERMODYNAMIC PROFILES EVIDENT OVER SERN
MO. REF WW 776 AND RELATED MESOSCALE DISCUSSIONS FOR NEAR-TERM
GUIDANCE ON SVR POTENTIAL FROM THIS ACTIVITY. AIR MASS SHOULD
STABILIZE AFTER SUNSET FROM COMBINATION OF GRADUAL SFC COOLING AND
INCREASING COVERAGE OF OUTFLOW AIR.
FARTHER SW...SCATTERED TO WIDELY SCATTERED TSTMS IN BANDS AND
CLUSTERS WERE PRIMARILY CONCENTRATED IN OUTFLOW-DOMINANT CLUSTER
FROM PERMIAN BASIN INTO TRANS-PECOS REGION OF W TX...AND FROM WRN
OZARKS TO CENTRAL TX. ISOLATED GUSTS APCHG SVR LEVELS STILL MAY
OCCUR FOR ANOTHER 1-2 HOURS...ESPECIALLY WITH ACTIVITY OVER
S-CENTRAL/SERN PLAINS INTO NWRN AR. HOWEVER...CONTINUED SFC
DIABATIC COOLING SHOULD STABILIZE BOUNDARY LAYER AND REDUCE BOTH
CONVECTIVE COVERAGE AND ALREADY MRGL SVR THREAT FOR REMAINDER
EVENING.
...NRN PLAINS...
WIDELY SCATTERED TSTMS ACROSS WRN DAKOTAS WILL CONTINUE TO POSE SVR
WIND/HAIL THREAT AS THEY MOVE IN FAN-SHAPED PATTERN -- EWD TO NEWD
ACROSS ND AND SEWD OVER SD...LATTER FOLLOWING PRONOUNCED SFC MIST
AXIS S OF WARM FRONT. SIGNIFICANT HAIL THREAT IS LIKELY FROM
SUPERCELLS...INCLUDING THAT OVER S-CENTRAL SD ATTM. REF WW 775 AND
LATEST MESOSCALE DISCUSSIONS FOR NEAR-TERM SVR FCST.
OVERNIGHT...PROGS STRONGLY INDICATE UPSCALE GROWTH OF EXISTING
CONVECTION AND/OR ADDITIONAL DEVELOPMENT IN LOW LEVEL WAA
ZONE...NEAR NOSE OF 35-35 KT 850 MB SPEED MAX. MIXTURE OF
FORWARD-PROPAGATIONAL AND BACKBUILDING CONTRIBUTIONS TO MCS MOTION
IS LIKELY...PRIND NET SEWD MOTION PROBABLE ACROSS ERN SD. DAMAGING
GUSTS AND OCCASIONAL HAIL ARE POSSIBLE.
...MID-ATLANTIC REGION...
ORGANIZED SVR POTENTIAL IN AND NEAR WW 774 APPEARS TO BE DIMINISHING
IN RELATION TO STABILIZING BOUNDARY LAYER...PER MESOSCALE DISCUSSION
1966. EXPECT POTENTIAL TO BECOME PROGRESSIVELY MORE MRGL THROUGH
REMAINDER EVENING AS NOCTURNAL SFC COOLING AND OUTFLOW EACH ACT TO
DIMINISH SFC-BASED INSTABILITY.
..EDWARDS.. 07/31/2008
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