Monday, October 25, 2010

MODERATE RISK AT SOUTH OF GREAT LAKES,USA



METD WEATHER
AKSHAY DEORAS
Severe Weather Forecaster

Concerning- Moderate risk
IMG-1 MDT RISK
IMG-2 the 850mb map

A classic strong 160kt jet stream is digging in USA currently over Western USA and developing in the next 24hrs will bring a round of Severe Weather in areas south of Great lakes
Seen from 18z+24hrs 300mb plot, the trough will develop and severe weather will plunge at the nose of it briefly over Eastern,South Eastern Illinois,much of Indiana,Ohio and extending till southern limits of Michigan.

Surface Cyclogenesis has already started as a strong low pressure area is building in Northern USA due to the jet and will move east with the stationary front at the Canadian Border into Minnesota,Wisconsin.
On Tuesday, strong low pressure less than 990mb will sweep east with the cold front in the southern areas of Great lakes(Areas mentioned above) associated with very strong low level jets of 60kt adding to Moderate threat and the warm sector resting with a dewpoint near to 70F. Instability (Max and AVG 30mb) seems to be less as compared to an ideal setup but CAPE values nearing 2000J/Kg added with good Precipitable water (1"+) will develop over Eastern Illinois to Indiana in a solid Wind shear environment(Ground helicity 0-1km) upto 200m2 s2 will be developing over Indiana later of the day.
Main threat lies for the Wind as strong surface winds are expected in the above regions as the linear thunderstorms brace east with the air pressure moving east at Canada border
Hails also will be there and some isolated tornadoes possible.

As per me, Threat for damaging wind gusts and hails is more than tornado. Tornado chance is more in North,NE Indiana and Central Ohio.

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