Tropical thundery Friday! Low level jet stream rules

Update 8:50am Friday:

Our steamy air mass is triggering scattered showers and thunderstorms this Friday.

Look for scattered storms with thunder and local downpours.

With dew points well into the 60s to near 70 degrees, some of the rainfall could be on the heavy side.

Here’s the latest Twin Cities radar loop to track the storms.

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Radar shows scattered thunder & rain Friday morning.

PH

*****

Summer is back for most of Minnesota!

A warm front has pushed north into Minnesota, and a warm humid air mass is moving in.

A steamy Friday has the look and feel of July on the weather maps and in the air.

The Front:

The warm front is the leading edge of a low pressure system in the Northern Rockies. The front will bisect Minnesota Friday, bringing warm air to almost all of the state.

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Twin Cities NWS Weather Story highlights warm front Friday.

The only exception to the warmth is the North Shore where southeast winds may keep temps mired in the 50s and lower 60s near the lake.

The best chance for any severe storms (a slight risk) appears to be in northern Minnesota.

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SPC risk areas Friday.

The Air Mass:

The air mass behind the front is juicy to say the least.

Temperatures in the upper 80s pushed into southwest Minnesota Thursday, and a “hot front” of sorts blazed into western Kansas, where bank thermometers pushed 100 degrees late Thursday.

WEATHER ROUNDUP FOR KANSAS

NATIONAL WEATHER SERVICE GOODLAND KS

500 PM CDT THU JUN 02 2011

NOTE: “FAIR” INDICATES FEW OR NO CLOUDS BELOW 12,000 FEET WITH NO

SIGNIFICANT WEATHER AND/OR OBSTRUCTIONS TO VISIBILITY.

NORTHWEST KANSAS

CITY SKY/WX TMP DP RH WIND PRES REMARKS

GOODLAND CLOUDY 92 50 23 S26G35 29.75F

HAYS MOSUNNY 97 57 26 S29G39 29.77F HX 95

HILL CITY PTSUNNY 100 53 20 S25G35 29.71F HX 98

RUSSELL MOSUNNY 95 57 27 S29G37 29.77F

$$

SOUTHWEST KANSAS

CITY SKY/WX TMP DP RH WIND PRES REMARKS

DODGE CITY SUNNY 97 48 18 S26G37 29.81F

ELKHART N/A 95 50 21 S18 N/A

GARDEN CITY SUNNY 100 49 17 S26G39 29.79F HX 97

GREAT BEND MOSUNNY 91 55 29 S26G33 29.82F

LIBERAL MOSUNNY 99 55 23 S29G38 29.84F HX 97

PRATT SUNNY 93 48 21 S25G37 29.86F

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Heat bubbles north Thursday.

Upper 80s to near 90 look likely for southern Minnesota Friday afternoon. If enough of Thursday’s Kansas heat wave works north into the system, we could see some readings well into the 90s in southern Minnesota.

Cool front=nicer weekend!

The passing low pressure system will drag a cool front through Minnesota Friday night into early Saturday. A fresh Canadian air mass will sail in for the weekend with much drier and somewhat cooler (but still pleasantly warm) air.

Look for highs near 80 this weekend with comfortable dew points dropping into the 50s. A stray thunderstorm can’t be ruled out for Sunday afternoon.

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Dew points crash this weekend.

Low Level Jet Stream = windy day!

Summer in Minnesota and the plains is known for warm to hot and often windy southerly breezes. You can usually thank the low level jet stream for a windy warm summer day.

Meteorologists call “main” jet stream the “Polar Front Jet Stream.” This fast moving ribbon of air around 18.000 feet above ground level races through the mid latitudes and steers storm systems along its path.

A second jet stream lower in the atmosphere becomes more pronounced at times during summer. This so called “Low Level Jet” (LLJ in meteorologist “geek speak”) races about 5,000 feet above us, much closer than the upper level jet.

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The LLJ can blow anywhere from 35 to over 50 mph in different scenarios, and often “mixes down” to ground level to create windy summer days, and to add fuel to developing thunderstorms.

The LLJ is notorious for providing energy to help trigger “nocturnal” thunderstorms where it intersects with warm frontal boundaries late at night in summer.

The LLJ pumps warm humid air straight from the Gulf of Mexico into Minnesota during the summer. IF you like it hot windy, and humid in summer, you can usually thank the LLJ!

PH

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