Sunday, August 16, 2009

Flooding T-storms Nearby

(Update: 4:10 am, Sunday). The local NWS has issued Flash Flood warnings for counties just to the south/west of the St. Cloud area through 9 am Sunday morning , the result of some 3-4" rainfall amounts nearby. This graphics shows estimated rainfall for the entire storm, yellow translates into at least 1.5" of rain, bright red is 3" and darker red is 4" - and the rains continue to fall HARD. A slow-moving band of T-storms dumping copious rains on the same counties may result in some 3-6" amounts by mid morning, enough for serious flash flooding of streets and streams. If you live in a flood-prone area be ready to head to safety/higher ground. Above all: avoid driving through flooded-out areas - this is the #1 source of death during severe weather scenarios - people underestimating how deep the water is, only to be swept away to their deaths. All it takes is 6" of rapidly moving water to knock an adult off their feet; 2 feet of rapidly moving water can turn a car or SUV into a boat. Don't assume that just because you're sitting high off the ground, in a truck or SUV, you're somehow safer from the floodwaters. You're not. Here is the complete text from the Chanhassen National Weather Service:

Storm Estimated Rainfall (key on the far left of the screen). Doppler estimated rainfall amounts as of 4 am for the entire storm, roughly the last 24 hours.

Basic Reflectivity Doppler, 4:30 am, Sunday. This is the standard Doppler image, showing areas of rain and hail. The most intense rain/hail shows up as yellow/orange/red, where rain is falling at the rate of 1-2"/hour. The entire line of severe storms, possibly an intensifying "MCS" system, a meso-convective system, more typical of June than mid August, will be pushing through the Twin Cities between 5-7 am, accompanied by local rainfall amounts of 1-2"+, enough to put another very large dent in our drought.

Here is the Flood Warning text just south/west of St. Cloud:

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
257 AM CDT SUN AUG 16 2009

THE NATIONAL WEATHER SERVICE IN THE TWIN CITIES HAS ISSUED A

* FLASH FLOOD WARNING FOR...
KANDIYOHI COUNTY IN CENTRAL MINNESOTA
NORTHWESTERN MEEKER COUNTY IN CENTRAL MINNESOTA
SOUTHERN STEARNS COUNTY IN CENTRAL MINNESOTA

* UNTIL 900 AM CDT

* AT 252 AM CDT...LOCAL LAW ENFORCEMENT OFFICIALS REPORTED MINOR
FLOODING IN THE WILLMAR AREA DUE TO RAINFALL AMOUNTS OF TWO TO
LOCALLY 3.5 INCHES SINCE 11 PM. MORE THUNDERSTORMS WILL BE MOVING
INTO THE WARNED AREA WITH RAINFALL RATES INCREASING TO TWO INCHES
PER HOUR BY 4 AM. THIS WILL CAUSE FLASH FLOODING...ESPECIALLY IN
AREAS THAT HAVE ALREADY RECEIVED FLOODING EARLIER. THE MOST PRONE
AREAS THAT WILL FLOOD ARE THE TOWNS OF WILLMAR AND PAYNESVILLE.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR.

MINOR FLOODING HAS ALREADY OCCURRED IN THE WILLMAR AREA WITH SOME
BASEMENT FLOODING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FLOODING IS OCCURRING OR IS IMMINENT. MOST FLOOD RELATED DEATHS OCCUR
IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED BRIDGES...
DIPS...OR LOW WATER CROSSINGS. NEVER TRY TO CROSS A FLOWING STREAM...
EVEN A SMALL ONE...ON FOOT OR IN A VEHICLE.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN THE
TWIN CITIES.

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