Flash Flood Warning for the Metro Area

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
101 AM CDT SAT AUG 8 2009

THE NATIONAL WEATHER SERVICE IN THE TWIN CITIES HAS ISSUED A

* FLASH FLOOD WARNING FOR...
EASTERN CARVER COUNTY IN EAST CENTRAL MINNESOTA
NORTHERN DAKOTA COUNTY IN EAST CENTRAL MINNESOTA
SOUTHERN HENNEPIN COUNTY IN EAST CENTRAL MINNESOTA
SOUTHERN RAMSEY COUNTY IN EAST CENTRAL MINNESOTA
SOUTHERN WASHINGTON COUNTY IN EAST CENTRAL MINNESOTA

* UNTIL 500 AM CDT

* AT 1258 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS THE
WARNED AREA...AND ESTIMATED THAT 2 INCHES OF RAIN HAS FALLEN SINCE
MIDNIGHT ACROSS THE SOUTHERN TWIN CITIES METRO AREA.

Doppler Radar from 1:30 am Saturday morning, showing a nearly stationary line of strong/severe thunderstorms. Individual cells within the line are moving east/northeast, but the entire band of heavy weather has shown little movement since 10 pm, thus the Flash Flood Warning, which means flooding is imminent. People living in or near poor drainage areas or next to small streams that routinely flood should stay alert, and be ready to move to higher ground.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
MINNEAPOLIS...ST PAUL...BAYPORT...BLOOMINGTON...CHANHASSEN...
CHASKA...COTTAGE GROVE...DEEPHAVEN...EAGAN...EDEN
PRAIRIE...EDINA...EXCELSIOR...FALCON HEIGHTS AND GOLDEN VALLEY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

ADDITIONAL RAINFALL AMOUNTS OF 2 TO 3 ARE POSSIBLE IN
THE WARNED AREA IN THE NEXT 3 HOURS.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. DO
NOT ENTER THE WATER. TURN AROUND AND MOVE UP TO HIGHER GROUND TO
ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS SUBJECT TO FLOODING WHEN
WATER BEGINS RISING.

_____________________________________

The Real Meat and Potatoes

Todd's Outlook for the Twin Cities

Saturday: Partly sunny, hot and very humid. Chance of a few nighttime T-storms (some severe). High: 92 (heat index nearing 100).

Tonight: Showers and storms possible. Low 72.

Sunday: Mix of clouds and sun, best chance of a T-shower early morning and again late afternoon. High: 89

Monday: Sunnier, slightly cooler, less humid. High: 84

Tuesday: Mostly sunny and pleasantly warm. High: 86

Wednesday: Sunny, bordering on hot. High: near 88

Thursday: Less sun, chance of a T-shower. High: 87

Ahh, the mighty BUFKIT - one of my favorite forecasting tools, which looks like a bunch of garbage, but to be honest, it can tell a lot... The meteorological equivalent of looking into a crystal ball. Hour by Hour this computer model can look into the future, tell us what may be. Keep in mind that this isn't etched in stone, but it gives us (meteorologists) a good idea of what to expect or what to watch for given atmospheric conditions at that time. It's a meteoroligists job to decifer the information and make an educated guess on whether or not the information, given by ridiculous mathematical calculations, are true or not. With that said, I've highlighted a few main points from BUFKIT at a given time period for Saturday (5pm), which is highlighted by the blue circle in the lower right. Take a look at the blue cirle in the upper left. This is the models interperetation of the amount of instability in the atmosphere, CAPE or Convective Available Potential Energy, at that moment. All the red lines reaching horizontally below that, indicate other instability parameters that are sufficient for T-Storm development. The only other two blue circles I've highlighted, mark the temperature in degrees Celcius, which is the number/number format seen in the bottom part of the BUFKIT. Just above that is the last blue circle, which indicates rain falling at that moemet. Again, this is not to be taken litterally at 5pm, but it may be a good indication of what may happen if everything comes together just right.

This image shows the risk of severe weather for our Saturday:

The image below shows the best potential for storms by percentages, a 30% chance through central Minnesota is quite impressive. Hail, high winds and an isolated tornado can't be ruled out today.

Keep an eye on the sky and an ear on your favorite website, tv station and or radio for any severe watches or warnings that may be issued later today. Have a good weekend.