SWODY1
SPC AC 171947
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0247 PM CDT THU MAR 17 2011
VALID 172000Z - 181200Z
...NO SVR TSTM AREAS FORECAST...
--- UPDATES ---
ONLY VERY MINOR CHANGES MADE TO WRN PERIPHERY OF MIDWEST GEN THUNDER
LINES BASED ON COMBINATION OF CONVECTIVE AND BOUNDARY TRENDS.
BRIEF/ISOLATED THUNDER MAY OCCUR OVER PORTIONS MID MS VALLEY DURING
ROUGHLY 03-09Z TIME FRAME...HOWEVER THIS AREA WILL BE IN RELATIVE
MIN OF LOW-LEVEL ASCENT COMPARED TO OTHER PORTIONS OF FRONTAL ZONE.
TSTM PROBABILITIES APPEAR TOO LOW FOR CATEGORICAL AREA THERE ATTM.
..EDWARDS.. 03/17/2011
.PREV DISCUSSION... /ISSUED 1119 AM CDT THU MAR 17 2011/
...UPPER MIDWEST/GREAT LAKES/NEW ENGLAND...
PHASING OF VORTICITY MAXIMA OVER THE NRN PLAINS AND SRN MANITOBA IS
IN PROCESS WITH CONJOINED MIDLEVEL SYSTEM TRANSLATING EWD THROUGH
THE GREAT LAKES DURING THE D1 PERIOD. MASS RESPONSE TO THIS FEATURE
WILL RESULT IN THE NEWD DEVELOPMENT OF A 40-50 KT SWLY LLJ THROUGH
THE GREAT LAKES...NEW ENGLAND AND ST. LAWRENCE VALLEY. ASSOCIATED
WARM THERMAL AND MOISTURE ADVECTIONS OCCURRING ALONG THE LLJ AXIS IN
CONJUNCTION WITH DCVA IN ADVANCE OF MIDLEVEL SYSTEM WILL BE
SUPPORTIVE OF SPORADIC...ELEVATED TSTM DEVELOPMENT TODAY INTO
TONIGHT. GIVEN THE RELATIVELY COOL THERMAL PROFILES IN THE
MIDLEVELS...SOME SMALL HAIL MAY ACCOMPANY THE MOST INTENSE
STORMS.
...ERN KS/WRN MO/NERN OK...
12Z OBSERVED SOUNDINGS OVER THE CNTRL AND SRN PLAINS SAMPLED A
WELL-DEFINED EML AND ASSOCIATED CAP ATOP A MODESTLY MOIST BOUNDARY
LAYER CHARACTERIZED BY DEW POINTS IN THE 50S TO LOWER 60S. LITTLE
CHANGE IN THE MIDLEVEL PATTERN IS FORECAST OVER THE NEXT 24-HR
SUGGESTING THAT CAP WILL LIKELY REMAIN IN TACT OVER THE CNTRL/SRN
PLAINS THROUGH MUCH OF THE D1 PERIOD. THE EXCEPTION WILL BE ACROSS
DISCUSSION AREA LATER TONIGHT WHERE A STRENGTHENING NOCTURNAL LLJ
WILL ENHANCE LIFT ALONG COLD FRONT ADVANCING SEWD INTO THE REGION.
HERE...MODEL FORECAST SOUNDINGS SUGGEST THAT CAP MAY BE SUFFICIENTLY
ERODED TO ALLOW FOR ISOLATED TO WIDELY SCATTERED TSTM DEVELOPMENT.
THE PRESENCE OF STEEP MIDLEVEL LAPSE RATES AND MUCAPE AROUND 1000
J/KG MAY FOSTER BRIEFLY STRONG STORMS CAPABLE OF SMALL HAIL.
...WRN U.S...
EWD PROGRESSION OF MIDLEVEL TROUGH THROUGH THE INTERMOUNTAIN WEST
AND ASSOCIATED PLUME OF STEEP MIDLEVEL LAPSE RATES MAY ALLOW FOR THE
ONSHORE DEVELOPMENT OF LOW-TOPPED TSTMS ALONG THE ORE/NRN CA COASTS
THROUGH THE PERIOD. ADDITIONAL...ISOLATED TSTM DEVELOPMENT WILL BE
POSSIBLE LATER TODAY INTO TONIGHT INVOF SURFACE FRONT AND
OROGRAPHICALLY-FAVORED TERRAIN OVER THE 4-CORNERS REGION.
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