Updraft: May 10, 2011 Archive

Like July; A run at 90; Severe risk late today

Posted at 8:55 AM on May 10, 2011 by Paul Huttner (1 Comments)
Filed under: Springtime

We all know spring can be short in Minnesota. But even this seems a bit ridiculous.

"Instant summer" kicks in today, as a powerful warm front pushes north from Iowa.

South of the front, temperatures hit 100 Monday in Nebraska and Kansas. It was 90 degrees as close as northwest Iowa with several records smashed.

The warm front will take up a position just south of the metro later today. Temperatures should surge into the 90s in southern Minnesota this afternoon, with the metro making a run at 90. Where we end up will depend on two things... just how much cloud cover we get today and how far north the front can push. If we get enough sun and the front eases north into the metro, we could hit 90 at MSP Airport late today.

Dew points on the rise:

You'll notice the heat later today, and the increasing moisture in the atmosphere. Dew points will climb into the 60s today. That's when most Minnesotans start to notice that it feels humid outside.

Models show dew points rising into the 60s & maybe 70s!

That moisture is also available as fuel for thunderstorms if they do develop.

Slight risk:

I've been showing you the SPC risk areas that include Minnesota today.

Here's the technical discussion from SPC. I've highlighted the area I think is most important today.

...MN/WI...

SURFACE LOW OVER ERN SD IS FORECAST TO DEVELOP NWD OR NWWD TODAY IN CONJUNCTION WITH STRONG VORTICITY MAXIMUM LIFTING NNEWD THROUGH THE WRN DAKOTAS. AS THIS OCCURS...ASSOCIATED WARM FRONT WILL
CONCURRENTLY LIFT NWD...EXTENDING FROM THE RED RIVER VALLEY TO SRN
WI BY LATE AFTERNOON/EARLY EVENING. BOUNDARY LAYER DEWPOINTS IN THE
60S AND STEEP MIDLEVEL LAPSE RATES WILL CONTRIBUTE TO A STRONGLY
UNSTABLE AIR MASS S OF WARM FRONT TODAY WHERE MLCAPE VALUES WILL
INCREASE TO 2500-3500+ J/KG.

LATEST MODEL GUIDANCE REMAINS CONSISTENT IN SUGGESTING THAT THE STRONG HEIGHT FALLS/FORCING FOR ASCENT ATTENDANT TO ABOVE-MENTIONED VORTICITY WILL REMAIN TO THE W OF THE REGION THROUGH THIS
EVENING...LEAVING SURFACE-BASED STORM INITIATION IN QUESTION DUE TO
THE STRENGTH OF THE CAP. THE MOST PROBABLE AREA OF STORM
DEVELOPMENT WILL BE NRN OR CNTRL MN LATE THIS AFTERNOON INTO EVENING
INVOF SURFACE FRONTAL OCCLUSION.

SHOULD STORMS DEVELOP...THE COMBINATION OF THE STRONG INSTABILITY
AND VERTICALLY VEERING WIND PROFILES WILL SUPPORT SUPERCELL
DEVELOPMENT WITH A RISK FOR VERY LARGE HAIL...DAMAGING WINDS AND A
FEW TORNADOES. SUBSEQUENT UPSCALE GROWTH TO A SEWD-MOVING MCS WOULD BE POSSIBLE TONIGHT WITH A CONTINUED THREAT FOR HAIL AND DAMAGING WINDS INTO PARTS OF WI.

But will they blow?

Diagnosing severe weather is a little like completing a puzzle. You may have most of the pieces in place, but if just one key piece is missing, you can't complete the picture.

Our atmosphere has plenty of what we call "conditional instability" today over Minnesota. But we may not have a "trigger" to get storms firing. And the atmosphere reamins "capped" over much of southern Minnesota.

What is "capping?"

We all know warm air rises. In the atmosphere warm air will rise until it encounters a warmer or more "stable" layer above. In meteorology we call this a "cap" because it puts a lid on thunderstorm development.

You can have all the wind shear and unstable air in the lower layers, but until you can "bust the cap" no storms will develop.

If you look at today's upper air "sounding" you can see the little bumps in the temperatures below. There are two "caps" today between about 5,000 and 9,000 feet above ground level. This may be enough to prevent storms from forming later today in southern Minnesota.

Twin Cities Upper Air sounding shows "capping" that may prevent storms.

Right now it looks like the best chance of breaking the cap could come after dark or overnight tonight if at all.

Stay tuned....

Storms rumble up north:

Meanwhile big storms are rumbling through more unstable air in northern Minnesota. Storms near Bemidji have been "hailers" today, with several reports of large hail.

DLH: 10 E Fort Ripley [Crow Wing Co, MN] trained spotter reports HAIL of quarter size (M1.00 INCH) at 05:29 AM CDT --

Expect storms to continue to fire in northern Minnesota today, and a few may be severe.

Memphis floods approach record levels:

The mighty Mississippi reaching levels not seen since 1937 in Memphis. Records may fall as the river stays near crest for the next few days.

PH

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