SWODY2
SPC AC 300600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT WED APR 30 2008
VALID 011200Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS ERN NEB/IA SSWWD TO
ERN RED RIVER VALLEY REGION OF TX/OK...
...SYNOPSIS...
PRIMARY UPPER AIR FEATURE FOR THIS FCST WILL BE CYCLONE NOW MOVING
FARTHER INLAND SRN BC...WITH TROUGHING SWD ACROSS NRN CA. AS THIS
SYSTEM MOVES OVER NRN ROCKIES LATE DAY-1...SPEED MAX IS FCST TO DIG
SEWD AROUND SWRN/SRN RIM OF THIS VORTEX...WITH NEW PRIMARY
CIRCULATION CENTER DEVELOPING BY APPROXIMATELY 2/00Z VICINITY SWRN
NEB. THIS SCENARIO IS SUPPORTED BY SREF CONSENSUS AS WELL AS
OPERATIONAL NAM/NGM...SPECTRAL BEING SOMEWHAT FARTHER NE AND FASTER
WITH LOW-MIDLEVEL CYCLONE OCCLUSION.
ASSOCIATED SFC CYCLONE SHOULD LIFT NEWD SLOWLY FROM VICINITY KS/NEB
BORDER TO ERN/NERN NEB DURING DAY...WITH OCCLUSION TRIPLE POINT
PROPAGATING EWD ALONG WARM FRONT OVERNIGHT. WARM FRONT SHOULD LIFT
NWD SLOWLY ACROSS IA/NRN IL AND OVER PORTIONS SRN LOWER MI BY END OF
PERIOD. MEANWHILE...COLD FRONT IS FCST TO MOVE SEWD ACROSS SRN HIGH
PLAINS...WRN OK AND WRN/CENTRAL KS BEFORE END OF PERIOD. BY AROUND
2/00Z...DRYLINE SHOULD EXTEND FROM COLD FRONTAL INTERSECTION --
INVOF EXTREME SERN NEB -- SSWWD ACROSS ERN KS TO NEAR DFW METROPLEX
AND INTO CENTRAL TX. COLD FRONT WILL OVERTAKE DRYLINE FROM N-S
ACROSS REGION NOCTURNALLY.
...CENTRAL/SRN LOW PLAINS...LOWER MO VALLEY TO NE TX...
BASIC SFC/UPPER PATTERN IS QUITE FAVORABLE CLIMATOLOGICALLY FOR
EARLY MAY SVR OUTBREAK. HOWEVER...NON-TRIVIAL CONCERNS LINGER
REGARDING BOTH DAYTIME CAPPING AND QUALITY AND NWD EXTENT OF
MOISTURE WITHIN WARM SECTOR...KEEPING UNCONDITIONAL SVR
PROBABILITIES BELOW MDT RISK CATEGORICAL THRESHOLDS ATTM.
EARLIEST SVR POTENTIAL SHOULD DEVELOP CLOSE TO SFC LOW OVER NERN
KS/SERN NEB/SRN IA...AND ADJACENT SEGMENT OF WARM FRONT. TYPICALLY
THIS WOULD BE SOME CONCERN FOR SMALL/LOW-TOPPED SUPERCELLS WITH
TORNADO THREAT...HOWEVER THIS POTENTIAL APPEARS VERY
CONDITIONAL/UNCERTAIN ATTM. FCST SOUNDINGS SUGGEST COMBINATION OF
SOMEWHAT MEAGER MOISTURE...COOL SFC TEMPS AND SOMEWHAT ERRATIC
DIRECTIONAL WIND PROFILE ATOP BACKED SFC FLOW. WITH
TIME...HOWEVER...SFC AIR MASS SHOULD HEAT/MOISTEN AHEAD OF
FRONT/DRYLINE OVER NWRN MO...SERN IA AND NERN KS...GROWING TOTAL SVR
POTENTIAL THROUGH LATE AFTERNOON/EARLY EVENING.
FARTHER S ACROSS SERN KS/SWRN MO/ERN OK REGION...EXPECT LESS DIURNAL
CONVECTIVE COVERAGE BUT GREATER POTENTIAL FOR SIGNIFICANT SVR WITH
THOSE STORMS THAT DO FORM. SFC DEW POINTS UPPER 50S TO LOW 60S ARE
EXPECTED DURING DAY...WITH MID 60S OVER PORTIONS ERN OK...INCREASING
FROM S-N IN PREFRONTAL AIR MASS DURING EVENING. TORNADOES STILL ARE
POSSIBLE IN ADDITION TO THREAT FOR LARGE/DAMAGING HAIL...ESPECIALLY
WITH ANY MATURE/DISCRETE SUPERCELLS THAT CAN MOVE INTO FAVORABLE
BOUNDARIES AND/OR EVENING LCL REDUCTIONS ASSOCIATED WITH WEAK
DIABATIC SFC COOLING. SLGT BACKING OF SFC WINDS BENEATH
STRENGTHENING LLJ ALSO SHOULD INCREASE HODOGRAPH SIZE SUBSTANTIALLY
NEAR AND AFTER 00Z...FOR A FEW HOURS WHILE EFFECTIVE LIFTED PARCELS
STILL ARE ROOTED AT SFC. PARTICULARLY OVER ERN/SERN OK AND RED
RIVER REGION...TIMING/COVERAGE OF CONVECTIVE INITIATION WILL BE MAIN
UNCERTAINTY BECAUSE OF STG CAPPING...INDICATING POTENTIAL FOR VERY
ISOLATED BUT STILL SIGNIFICANT-SVR PRODUCING SUPERCELLS.
AFTER DARK...LINE OF TSTMS MAY BUILD SWWD ALONG COLD FRONT TO
SWD-PROPAGATING FRONT/DRYLINE INTERSECTION. ALTHOUGH MOISTURE WILL
BE MORE FAVORABLE FROM SERN OK SSWWD INTO CENTRAL TX AHEAD OF
FRONT/DRYLINE...SWD EXTENT OF SVR POTENTIAL BECOMES MORE CONDITIONAL
BECAUSE OF MESOSCALE BOUNDARY UNCERTAINTIES...WEAKER UPPER
SUPPORT...AND STRONGER CAPPING WITH SWD EXTENT.
..EDWARDS.. 04/30/2008
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