Severe Thunderstorm Watch 3:30 p.m. 6/23/09

Statement as of 3:30 PM CDT on June 23, 2009

The NWS Storm Prediction Center has issued a

Severe Thunderstorm Watch for portions of

eastern into southwest Iowa

eastern into south central Nebraska

Effective this Tuesday afternoon and evening from 330 PM until 1000 PM CDT.

Hail to 2 inches in diameter... thunderstorm wind gusts to 70 mph... and dangerous lightning are possible in these areas.

The Severe Thunderstorm Watch area is approximately along and 40

statute miles north and south of a line from 55 miles east

northeast of Cedar Rapids Iowa to 25 miles west of Kearney

Nebraska. For a complete depiction of the watch see the

associated watch outline update (wous64 kwns wou1).

Remember... a Severe Thunderstorm Watch means conditions are

favorable for severe thunderstorms in and close to the watch

area. Persons in these areas should be on the lookout for

threatening weather conditions and listen for later statements

and possible warnings. Severe thunderstorms can and occasionally

do produce tornadoes.

Other watch information... continue... ww 497... ww 498... ww

499... ww 500...

Discussion... narrow area of severe thunderstorms should evolve

through the evening as convective outflow boundary/effective cold

front stalls from S-central/swrn neb into central/ern IA. Air mass

is extremely unstable... with MLCAPE to 5000 k/kg... which should

compensate for marginal deep layer shear. Intense updrafts will

remain capable of large hail/damaging winds... with more persistent

esewd moving clusters sustaining a greater risk of severe.

Aviation... a few severe thunderstorms with hail surface and aloft

to 2 inches. Extreme turbulence and surface wind gusts to 60

knots. A few cumulonimbi with maximum tops to 550. Mean storm

motion vector 27020.