Updraft: July 7, 2010 Archive

Nowcast: Locally heavy downpours

Posted at 2:34 PM on July 7, 2010 by Paul Huttner
Filed under: Rainfall

A quasi-stationary frontal boundary has set up right in the eastern half of the Twin Cities today. It appears this front will be the focus for scattered showers and thunderstorms through the evening.

Update 5:12pm:

Possible wall cloud near 494 and Hwy 169 on MNDOT traffic cam.

Update 5pm:

Hevay downpours in eastern Eden Prairie and west Bloomington prompt an urban flood advisory from NWS.

FLOOD ADVISORY
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
459 PM CDT WED JUL 7 2010

MNC053-080100-
/O.NEW.KMPX.FA.Y.0019.100707T2159Z-100708T0100Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
HENNEPIN MN-
459 PM CDT WED JUL 7 2010

THE NATIONAL WEATHER SERVICE IN THE TWIN CITIES HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR AREAS IN...
SOUTHEASTERN HENNEPIN COUNTY IN EAST CENTRAL MINNESOTA...

* UNTIL 800 PM CDT

* AT 455 PM CDT...TRAINED WEATHER SPOTTERS REPORTED THUNDERSTORMS
WITH HEAVY RAINFALL ACROSS THE ADVISORY AREA. A STORM SPOTTER
IN WESTERN BLOOMINGTON REPORTED RAIN FALLING AT A RATE OF AROUND 2
INCHES IN AN HOUR.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE SOME FLOODING TO
OCCUR...ESPECIALLY IN AREAS OF POOR DRAINAGE. SOME LOCATIONS THAT
MAY EXPERIENCE FLOODING INCLUDE...BLOOMINGTON...EDEN
PRAIRIE...EDINA AND RICHFIELD. THIS INCLUDES THE INTERSTATE 35
CONSTRUCTION AREA FROM BLOOMINGTON THROUGH RICHFIELD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

Update 4:30pm:

Twin Cities NWS issues NOWCAST on storms.

SHORT TERM FORECAST
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
426 PM CDT WED JUL 7 2010

MNZ076>078-083>085-092-093-072330-
BLUE EARTH-FARIBAULT-FREEBORN-GOODHUE-LE SUEUR-RICE-STEELE-WASECA-
INCLUDING THE CITIES OF...ALBERT LEA...MANKATO...OWATONNA...RED WING
426 PM CDT WED JUL 7 2010

.NOW...
HEAVY RAIN PRODUCING THUNDERSTORMS WILL CONTINUE TO ADVANCE
ACROSS SOUTH CENTRAL MINNESOTA LATE THIS AFTERNOON. SOME OF
THE STRONGER STORMS MAY DUMP AN INCH TO AN INCH AND A HALF OF
RAIN IN LESS THAN A HOUR. THIS MAY CAUSE SOME PONDING OF WATER
IN AREAS OF POOR DRAINAGE. AT 420 PM THE LEADING EDGE OF THE
STRONGER STORMS EXTENDED FROM NEAR NORTHFIELD TO OWATONNA TO THE
WELLS AND KIESTER AREA. BEFORE 530 PM THEY SHOULD REACH
ZUMBROTA...BLOOMING PRAIRIE AND ALBERT LEA.

$$

MNZ053-060>063-069-070-072330-
ANOKA-CHISAGO-DAKOTA-HENNEPIN-RAMSEY-SCOTT-WASHINGTON-
INCLUDING THE CITIES OF...MINNEAPOLIS...ST PAUL...STILLWATER
426 PM CDT WED JUL 7 2010

.NOW...
STRONG THUNDERSTORMS WILL AFFECT THE EASTERN TWIN CITIES METRO AREA
UNTIL AROUND 6 PM THIS EVENING. AT 420 PM THE STRONGER
STORMS WERE NEAR LINO LAKES...STILLWATER...COTTAGE GROVE...AND
HAMPTON. IN ADDITION TO VERY HEAVY RAIN SOME SMALL HAIL AND GUSTY
WINDS ARE ALSO POSSIBLE. SOME STREET FLOODING IS POSSIBLE AS AN INCH
OR MORE OF RAIN IS POSSIBLE IN LESS THAN AN HOUR. THESE STORMS WILL
GENERALLY MOVE TO THE NORTHEAST AT 15 TO 20 MPH.

$$

WIZ014>016-023>028-072330-
BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST CROIX-
INCLUDING THE CITIES OF...CHIPPEWA FALLS...EAU CLAIRE...LADYSMITH...
RICE LAKE
426 PM CDT WED JUL 7 2010

.NOW...
SCATTERED THUNDERSTORMS WILL AFFECT WEST CENTRAL WISCONSIN THROUGH
THE EARLY EVENING HOURS. AT 420 PM SOME OF THE STRONGER STORMS WERE
NEAR LADYSMITH TO BLOOMER TO EAU CLAIRE. OTHER STRONG STORMS WERE
BEGINNING TO CROSS THE ST. CROIX RIVER TOWARD NEW RICHMOND...
OSCEOLA...AND RIVER FALLS. SMALL HAIL AND VERY HEAVY RAIN IS
POSSIBLE FROM THE STRONGER STORMS. THEY WILL MOVE TOWARD THE
NORTHEAST AT 15 TO 20 MPH.

$$
BAP

Radar Update 3:47pm: Heavier rain cells continue to favor central and east metro for now. There is some sign that storms may "back build" into the central and western metro over the next two hours.

2:52pm radar update: Heavy downpours between downtown Minneapolis and St. Paul and the SE metro.

Twin Cities radar loop shows storms favoring the southest metro Wednesday afternoon.

It appears the heaviest rain corridor may favor the south and east half of the metro, as well as the I-35 corridor southward to Iowa. Since the storms are slow moving, the tropical downpours may result in some hefty rain totals over an inch in some areas.

As is often the case with summer convective thunderstorms, rainfall amounts will be highly localized. The western metro and areas to the west may see only widely scattered activity tonight, as a second cool front pushes in from the west. Still, a few thunderstomrs may pop up west of the frontal boundary.

It appears most of the storms will stay below severe limits, but some may produce locally heavy rains that may cause local street flooding this evening. Keep an eye on storms approaching from the southwest, especially in the eastern metro this evening.

-Latest Twin Cities radar loop

PH