SWODY1
SPC AC 030559
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT MON MAY 03 2010
VALID 031200Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM WRN IND THROUGH CENTRAL
AND SRN IL TO SERN MO...
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CAROLINAS SWWD TO THE
CENTRAL/ERN GULF COAST...
...SYNOPSIS...
UPPER PATTERN IS EXPECTED TO EVOLVE INTO MORE ZONAL FLOW BY 12Z
TUESDAY. A LEAD SHORTWAVE TROUGH LOCATED OVER THE LOWER GREAT
LAKES/UPPER OH VALLEY AT 12Z TODAY WILL MOVE ENEWD THROUGH THE NERN
STATES...WHILE AN UPSTREAM TROUGH TRACKS EWD FROM THE NRN PLAINS TO
GREAT LAKES/OH VALLEY THIS FORECAST PERIOD. NEXT UPSTREAM PACIFIC
SHORTWAVE TROUGH IS FORECAST TO AMPLIFY ESEWD INTO THE NRN ROCKIES/
ADJACENT CANADIAN PROVINCES. MEANWHILE...A COMPACT SHORTWAVE
TROUGH...CURRENTLY LOCATED OVER NM PER WATER VAPOR IMAGERY...WILL
TRACK EWD THROUGH THE SRN PLAINS THIS AFTERNOON REACHING THE LOWER
MS VALLEY BY 12Z TUESDAY.
IN THE LOW-LEVELS...A SURFACE FRONT INITIALLY SITUATED ALONG THE
APPALACHIANS SWWD TO THE CENTRAL GULF COAST WILL SHIFT EWD TOWARD
THE MID AND SERN ATLANTIC COAST. ELSEWHERE...A COLD FRONT WILL
INTENSIFY TODAY WHILE PROGRESSING EWD THROUGH THE UPPER GREAT LAKES
AND MID MS VALLEY. THE SWRN EXTENSION OF THIS BOUNDARY ANCHORED BY
A WEAK SURFACE LOW OVER TX WILL SHIFT EWD AS WELL.
...LOWER MI SWWD THROUGH MID MS VALLEY TO OZARKS...
A SHORTWAVE TROUGH TRANSLATING THROUGH THE NRN PLAINS LONGWAVE
TROUGH SHOULD REACH THE UPPER MS AND LOWER MO VALLEYS BY LATE THIS
AFTERNOON...AND THEN MOVE INTO THE OH VALLEY/SRN GREAT LAKES REGION
TONIGHT. SURFACE HEATING AND DEWPOINTS IN THE 50S AHEAD OF THE COLD
FRONT FROM THE OZARKS INTO NERN IL/IND BENEATH PLUME OF STEEP MID
LEVEL LAPSE RATES ADVECTING NEWD AHEAD OF THE UPPER TROUGH WILL
RESULT IN MLCAPE 500-1000 J/KG. THE GREATEST INSTABILITY SHOULD BE
FROM SERN-ERN MO TO WRN IND WHERE HIGHEST DEWPOINT VALUES /MID 50S/
ARE FORECAST TO RESIDE BY PEAK HEATING. TSTMS ARE EXPECTED TO
DEVELOP THIS AFTERNOON ALONG THE FRONT...AIDED BY INCREASING DEEP
ASCENT AHEAD OF APPROACHING SHORTWAVE TROUGH. SOME STRENGTHENING OF
SWLY MID LEVEL WINDS /40-50 KT/ WILL RESULT IN EFFECTIVE BULK SHEAR
/30-40 KT/ FOR ORGANIZED STORMS ACROSS THE SLIGHT RISK AREA. THE
DEEP LAYER SHEAR AND FAVORABLE THERMODYNAMICS/STEEP LAPSE RATES
SUGGEST BOTH HAIL AND STRONG WIND GUSTS SHOULD BE THE PRIMARY
THREATS. FARTHER NNE...INSTABILITY IS EXPECTED TO BE WEAKER INTO
LOWER MI. HOWEVER...AN INCREASE IN SWLY LOW LEVEL WINDS MAY ENHANCE
THE WIND GUST POTENTIAL WITH STORMS MOVING ACROSS THIS AREA DURING
THE LATE AFTERNOON/EVENING.
...CAROLINAS SWWD TO THE CENTRAL/ERN GULF COAST...
THIS REGION WILL RESIDE ALONG THE SRN PERIPHERY OF STRONGER
MID-UPPER LEVEL WINDS...RESULTING IN EFFECTIVE BULK SHEAR 40-60 KT
THROUGH THE FORECAST PERIOD. GENERALLY WEAK LAPSE RATES ACROSS THIS
SLIGHT RISK AREA TODAY ARE EXPECTED TO LIMIT THE DEVELOPMENT OF
STRONGER INSTABILITY...THUS PRECLUDING THE FORECAST OF HIGHER SEVERE
PROBABILITIES. THE GREATEST INSTABILITY /AROUND 1000 J/KG/ SHOULD
OCCUR WHERE SURFACE HEATING WILL BE STRONGEST. CURRENT FORECAST
SUGGESTS THIS SHOULD OCCUR ALONG THE CENTRAL/ERN GULF COAST
REGION...AND OVER THE CAROLINAS. GIVEN THE STRENGTH OF THE DEEP
LAYER SHEAR...A SLIGHT RISK IS BEING MAINTAINED FARTHER INLAND
ACROSS CENTRAL AL/GA...DESPITE THE POTENTIAL FOR WEAKER INSTABILITY.
SHEAR VECTORS ORIENTED PARALLEL TO THE FRONT MOVING ACROSS THIS
AREA SUGGESTS LINE SEGMENTS PRODUCING STRONG WIND GUSTS SHOULD BE
THE PRIMARY THREAT. HOWEVER...A 30 KT SWLY LLJ OVER THE ERN
CAROLINAS AND BACKED LOW LEVEL FLOW INTO THE CENTRAL/ERN GULF COAST
MAY SUPPORT AN ISOLATED TORNADO IN THESE AREAS.
...PART OF NRN TX/ADJACENT OK...
FORCING FOR ASCENT WITH THE COMPACT SHORTWAVE TROUGH SHOULD SUPPORT
ISOLATED TO SCATTERED TSTM DEVELOPMENT ACROSS NRN TX AND ADJACENT
SRN-SERN OK THIS AFTERNOON. EFFECTIVE BULK SHEAR AROUND 25 KT
SHOULD TEND TO LIMIT STORM ORGANIZATION WITHIN A MARGINALLY UNSTABLE
ENVIRONMENT. HOWEVER...STEEP LOW AND MID LEVEL LAPSE RATES SUGGEST
ISOLATED STRONG WIND GUSTS WILL BE POSSIBLE WITH ANY MORE SUSTAINED
STORMS...WITH A THREAT FOR ISOLATED HAIL AS WELL.
..PETERS/HURLBUT.. 05/03/2010
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