AM storms rumble through; PM severe threat looms

Update 10am:

Bow echo producing wind damage south of metro.

MPX: 5 W Green Isle [Sibley Co, MN] amateur radio reports HAIL of nickel size (M0.88 INCH) at 08:28 AM CDT --

MPX: Green Isle [Sibley Co, MN] amateur radio reports TSTM WND DMG at 08:30 AM CDT -- five inch diameter tree limbs down.

MPX: Lonsdale [Rice Co, MN] emergency mngr reports HAIL of nickel size (M0.88 INCH) at 09:15 AM CDT --

MPX: Northfield [Rice Co, MN] law enforcement reports TSTM WND DMG at 09:41 AM CDT -- trees down.

MPX: Northfield [Rice Co, MN] law enforcement reports HEAVY RAIN of U0.00 INCH at 10:00 AM CDT -- intersection filled with water. three cars stranded

Update 9:40am:

Storms will gradually fade in the metro this morning, but SPC is monitoring developing bow echo south & east of metro for possible watch.

MESOSCALE DISCUSSION 1705

NWS STORM PREDICTION CENTER NORMAN OK

0937 AM CDT SAT JUL 23 2011

AREAS AFFECTED...SERN MN AND WI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 231437Z - 231530Z

ISOLATED SEVERE STORM WAS MOVING EWD AT 35 KT THROUGH SERN MN AND

PORTIONS OF WI WILL BE MONITORED FOR A POSSIBLE WATCH ISSUANCE LATE

THIS MORNING OR AFTERNOON.

OVERNIGHT LINEAR MCS...WHICH STRETCHED FROM NWRN WI SEWD INTO SERN

MN...HAS GENERALLY WEAKENED DURING THE PAST COUPLE OF HOURS.

HOWEVER...AN INTENSE STORM WAS LOCATED JUST BEHIND THE BOUNDARY...

ABOUT 20 MILES SOUTH OF MSP. ALTHOUGH THIS STORM IS ELEVATED AND THE

AIS MASS AHEAD OF IT IS CURRENTLY WEAKLY UNSTABLE...THE STORM WAS

BEING SUSTAINED BY A WARM AND UNSTABLE AIR MASS BEING SPREAD NEWD BY

SWLY WINDS BETWEEN 700 AND 850 MB. GIVEN THE CURRENT THERMODYNAMIC

ENVIRONMENT...MARGINALLY SEVERE HAIL APPEARS TO BE THE MAIN

THREAT...ALONG WITH 35 TO 50 MPH WINDS. HOWEVER...WITH

HEATING/DESTABILIZATION OF THE AIR MASS...IF THE STORM CAN BE

MAINTAINED THROUGH THE MORNING AND BECOME SURFACE BASED...THE

POTENTIAL FOR LARGER HAIL AND WIND DAMAGE WOULD INCREASE...AND A

WATCH WOULD THEN BECOME MORE LIKELY.

..IMY.. 07/23/2011

Update 9:24am:

NWS update on storms moving into Wisconsin below....

SPECIAL WEATHER STATEMENT

NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN

923 AM CDT SAT JUL 23 2011

MNZ052-053-063-WIZ014-015-023>025-231530-

BARRON-CHISAGO-DUNN-ISANTI-PIERCE-POLK-ST. CROIX-WASHINGTON-

923 AM CDT SAT JUL 23 2011

...THUNDERSTORMS MOVING INTO

BARRON...CHISAGO...DUNN...ISANTI...PIERCE...POLK...ST. CROIX AND

WASHINGTON COUNTIES THROUGH 1030 AM CDT...

AT 922 AM CDT...WEATHER SERVICE RADAR WAS TRACKING STRONG

THUNDERSTORMS ALONG A LINE EXTENDING FROM 3 MILES SOUTHEAST OF

CHISAGO CITY TO 5 MILES EAST OF MARINE ON ST CROIX TO 3 MILES WEST OF

HOULTON TO 3 MILES SOUTH OF LAKELAND. THESE STORMS WERE MOVING EAST

AT 35 MPH.

WINDS UP TO 50 MPH ARE EXPECTED WITH THESE STORMS.

PEOPLE IN EASTERN WASHINGTON...NORTHERN PIERCE...NORTHWESTERN DUNN...

SOUTHEASTERN ISANTI...SOUTHERN CHISAGO...SOUTHERN POLK...SOUTHWESTERN

BARRON AND ST. CROIX COUNTIES...INCLUDING THE CITIES OF BURKHARDT...

HUDSON...SOMERSET...LAKELAND...LINDSTROM...CHISAGO CITY...SCANDIA...

CENTER CITY...HOULTON AND SHAFER...SHOULD MONITOR THE WEATHER

SITUATION CLOSELY. LISTEN FOR POSSIBLE WARNINGS AND BE PREPARED TO

TAKE APPROPRIATE ACTION SHOULD SEVERE WEATHER THREATEN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS THUNDERSTORM COULD INTENSIFY QUICKLY...SO BE READY TO ACT IF A

WARNING IS ISSUED.

STAY TUNED TO NOAA WEATHER RADIO...COMMERCIAL RADIO...OR YOUR LOCAL

TELEVISION STATIONS FOR LATER STATEMENTS AND POSSIBLE WARNINGS

CONCERNING THIS WEATHER SITUATION.

Update 9:17 am:

Latest warning for possible developing bow echo south of metro includes Dakota & Goodhue counties...

BULLETIN - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN

917 AM CDT SAT JUL 23 2011

THE NATIONAL WEATHER SERVICE IN THE TWIN CITIES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

SOUTHWESTERN DAKOTA COUNTY IN EAST CENTRAL MINNESOTA...

SOUTHWESTERN GOODHUE COUNTY IN SOUTHEAST MINNESOTA...

RICE COUNTY IN SOUTH CENTRAL MINNESOTA...

SOUTHEASTERN SCOTT COUNTY IN EAST CENTRAL MINNESOTA...

NORTHERN STEELE COUNTY IN SOUTH CENTRAL MINNESOTA...

* UNTIL 1015 AM CDT

* AT 914 AM CDT...RADAR INDICATED A LINE OF SEVERE THUNDERSTORMS...

CAPABLE OF PRODUCING QUARTER SIZE HAIL AND DAMAGING WINDS IN EXCESS

OF 60 MPH. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING FROM

NEW MARKET TO LONSDALE TO 6 MILES NORTHEAST OF KILKENNY...AND

MOVING SOUTHEAST AT 35 MPH.

LOCATIONS IN THE WARNING INCLUDE...

FARIBAULT...

NEW MARKET...

WEBSTER...

ELKO...

WARSAW...

DUNDAS...

NORTHFIELD...

MEDFORD...

RUSKIN...

NERSTRAND...

STANTON...

DENNISON...

KENYON...

BOMBAY...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THIS STORM...PREPARE IMMEDIATELY FOR

DAMAGING WINDS IN EXCESS OF 60 MPH AND LARGE HAIL. SEEK SHELTER NOW

INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS.

THIS STORM HAS A HISTORY OF PRODUCING DESTRUCTIVE WINDS AND LARGE

DAMAGING HAIL. SEEK SHELTER NOW INSIDE A STURDY STRUCTURE AND STAY

AWAY FROM WINDOWS!

Update 9:10am:

MPX: 1 W New Prague 4 [Scott Co, MN] trained spotter reports HAIL of pea size (E0.25 INCH) at 09:00 AM CDT -- pea to dime size hail with some quarter size. winds estimated 50 mph with 2 inch tree limbs down.

Update 8:46am:

Warning now for Scott & Carver storm on south edge of the metro....

-Twin Cities radar loop

BULLETIN - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN

846 AM CDT SAT JUL 23 2011

THE NATIONAL WEATHER SERVICE IN THE TWIN CITIES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

SOUTH CENTRAL CARVER COUNTY IN EAST CENTRAL MINNESOTA...

NORTHEASTERN LE SUEUR COUNTY IN SOUTH CENTRAL MINNESOTA...

NORTHWESTERN RICE COUNTY IN SOUTH CENTRAL MINNESOTA...

SOUTHERN SCOTT COUNTY IN EAST CENTRAL MINNESOTA...

* UNTIL 930 AM CDT

* AT 841 AM CDT...RADAR INDICATED A LINE OF SEVERE THUNDERSTORMS...

CAPABLE OF PRODUCING QUARTER SIZE HAIL AND DAMAGING WINDS IN EXCESS

OF 60 MPH. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING FROM

BELLE PLAINE TO HENDERSON...AND MOVING EAST AT 35 MPH.

LOCATIONS IN THE WARNING INCLUDE...

BELLE PLAINE...

JORDAN...

NEW PRAGUE...

VESELI...

LONSDALE...

WEBSTER...

NEW MARKET...

ELKO...

HEIDELBERG...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THIS STORM...PREPARE IMMEDIATELY FOR

DAMAGING WINDS IN EXCESS OF 60 MPH AND LARGE HAIL. SEEK SHELTER NOW

INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS.

REPORT ANY SIGNIFICANT WIND OR HAIL DAMAGE TO THE NEAREST LAW

ENFORCEMENT AGENCY...FOR RELAY TO THE NATIONAL WEATHER SERVICE.

Update 8:35am Saturday:

A batch of strong storms moving through metro on schedule this morning.

PH

SPECIAL WEATHER STATEMENT

NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN

827 AM CDT SAT JUL 23 2011

MNZ051>053-060>063-231430-

ANOKA-CHISAGO-HENNEPIN-ISANTI-RAMSEY-SHERBURNE-WASHINGTON-

827 AM CDT SAT JUL 23 2011

...THUNDERSTORMS MOVING INTO

ANOKA...CHISAGO...HENNEPIN...ISANTI...RAMSEY...SHERBURNE AND

WASHINGTON COUNTIES THROUGH 930 AM CDT...

AT 823 AM CDT...WEATHER SERVICE RADAR WAS TRACKING STRONG

THUNDERSTORMS ALONG A LINE EXTENDING FROM 8 MILES SOUTHEAST OF

PRINCETON TO ANDOVER TO PLYMOUTH. THESE STORMS WERE MOVING EAST AT 30

MPH.

WINDS UP TO 40 MPH ARE EXPECTED WITH THESE STORMS.

* LOCATIONS IN OR NEAR THE PATH OF THESE STORMS INCLUDE...

ST FRANCIS.

NEW HOPE.

OAK PARK.

SPRING LAKE PARK.

BODUM.

LAUDERDALE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF ON OR NEAR WHITE BEAR LAKE...GET OUT OF THE WATER AND MOVE

INDOORS OR INSIDE A VEHICLE. REMEMBER...LIGHTNING CAN STRIKE OUT TO

15 MILES FROM THE PARENT THUNDERSTORM. IF YOU CAN HEAR THUNDER...YOU

ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING. MOVE TO SAFE SHELTER

NOW. DON'T BE CAUGHT ON THE WATER IN A THUNDERSTORM!

A warm front is pushing north into Minnesota.

A line of storms in the Dakotas will push into western Minnesota early Saturday morning and move east.

-Latest Twin Cities radar loop

-Latest weather watches & warnings from Twin Cities NWS

A tornado watch is in effect until 2pm for the eastern Dakotas and a small sliver of western Minnesota.

The best chance for storms to approach the metro area appears to be early Saturday morning, but there are indications the heaviest storms could slide just north on the Twin Cities through St. Cloud & Brainerd early Saturday.

There is a slight risk for severe storms through Saturday, but it appears the highest chance for severe weather will be Saturday afternoon & evening. With some wind shear I am concerned about the possiblity of tornadoes late Saturday PM & evening in central & southern Minnesota...including the Twin Cities metro. The latest forecast models trend storms from the metro north...meaning we could be on the edge...but it looks like a close call.

Be prepared as you head out Saturday PM & evening.

Rainfall totals could be heavy, with an inch in many areas and several inches in some spots.

NAM rainfall projects several inches this weekend in southern Minnesota.

Modles cranking out 1"+ for MSP Airport through Saturday.

Sunday still looks like the best day of the weekend as drier air pushes in from Canada!

Seeley on Minnesota heat records this week:

From Mark's Weather Talk blog this week.

"At Moorhead, dewpoints hit 80 degrees F or higher everyday from the 16th to the 20th, topping out at 88 degrees F on July 19th with a Heat Index of 134 degrees F, both tentatively new statewide records.

The Twin Cities endured for the first time a period of three consecutive days with dewpoints hitting 80 degrees F or higher. On July 19th a new all-time dewpoint level was achieved with a reading of 82 degrees F, topped by a sub-hourly reading of 84 degrees F. These new records will have to be certified by the State Climate Office. Preliminary data also indicate a new Heat Index record of 124 degrees F was reached in the Twin Cities on the 19th.

Even far northern areas reached uncharted dewpoint and Heat Index values during this period. Hallock hit a dewpoint of 84 degrees F with a Heat Index of 111 degrees F on the 19th, while Winnipeg, Manitoba (Canada) reported a dewpoint of 77 degrees F and a Heat Index of 109 degrees F, both new records."

Heat wave spreads east:

Chack out this interesting temperature animation from NOAA as the heat wave spreads east this week.

Now the dew points and as humid air engulfs the nation.

NOAA Study: Are "stratospheric aerosols" offsetting global warming?

Check out this new study from NOAA:

The study suggests there is evidence that earth's climate would be warming even faster without tiny particles injected high into the stratosphere that are blocking sunlight from reaching earth.

"NOAA study: Increase in particles high in Earth's atmosphere has offset some recent climate warming

July 21, 2011

A recent increase in the abundance of particles high in the atmosphere has offset about a third of the current climate warming influence of carbon dioxide (CO2) change during the past decade, according to a new study led by NOAA and published today in the online edition of Science.

The new study focused on the most recent decade, when the amount of aerosol in the stratosphere has been in something of a "background" state, lacking sharp upward spikes from very large volcanic eruptions. The authors analyzed measurements from several independent sources - satellites and several types of ground instruments - and found a definitive increase in stratospheric aerosol since 2000.

"Stratospheric aerosol increased surprisingly rapidly in that time, almost doubling during the decade," Daniel said. "The increase in aerosols since 2000 implies a cooling effect of about 0.1 watts per square meter - enough to offset some of the 0.28 watts per square meter warmingeffect from the carbon dioxide increase during that same period.""

NOAA Graphic: Sources for "stratosperic aerosols."

PH

Update 2pm Friday:

Nice but warmer & more humid day today as scheduled. Temperatures are in the 80s to near 90 now in southern Minnesota.

You're feeling the humidity level is up again today. Take a look at dew points, which have pushed back into the 70s in southern Minnesota Friday afternoon.

A few showers & T-Storms have developed along the warm front which is pushing north today. Expect showers and a few T-Storms along the I-90 corridor to maybe as far north as Mankato this afternoon.

[image]

So far nothing severe and SPC has not issued any watches or mesoscale discussions for the area, but we'll keep an eye on things this afternoon. Expect rain south & west of the metro...and we'll see if the showers have enough oomph to make it to the Twin Cities by late PM/evening.

PH

Get ready for a roller coaster weather ride over the next 72 hours.

Friday:

Overall, Friday should be a pretty nice day in Minnesota. Some heat and humidity will begin to bubble north again, and you'll notice the rise in dew points Friday.

Dew points spike this weekend.

Highs will be in the lower 80s north, upper in the south, and may approach 90 in some areas.

Look for a mix of sun and more clouds Friday, and it appears any storms will hold off until after midnight Saturday in most areas, so Friday evening should be a great night to be outdoors.

Steamy "thunder sandwich" Saturday?

All weather bets are off after the clock strikes midnight early Saturday.

An upper level low pressure system spinning out of the northern Rockies will likely trigger a round over overnight showers & T-Storms moving from the eastern Dakotas into Minnesota in the wee hours of Saturday morning.

We could see an MCS develop, with widespread lighting, thunder, and heavy rain. The favored timing appears to be after midnight in western Minnesota and after 3am into early Saturday morning for the metro and eastern MN. There are some indications storms early Saturday may favor the northern half of Minnesota.

After the initial morning wave of storms, the forecast models paint a sunnier steamy pictuer for the midday and early afternoon hours. Temps could shoot up to near 90, and dew points could surge into the steamy upper 70s again...with a shot at 80 in some areas.

A second frontal wave could trigger another round of T-Storms late Saturday PM & evening. There is a risk that some of the storms could be severe Saturday late PM & evening. (Yes, I know...there's a Twins game at 3pm and the U2 concert at TCF Bank Stadium Saturday night!)

Let's see how the models tweak timing on Saturday's storm potential later Friday PM.

Splendid Sunday?

After a cool front cleans the humid gunk out of the atmosphere Sunday...it could be one of the best days of the summer!

Look for a return to sunshine, with highs in the mid to upper 80s and dew points falling into the comfy lower 60s!

Stay tuned as we tweak the weekend forecast Friday afternoon!

PH