Thursday, July 16, 2009

July Wind Chill - Record Chill Likely

Weather Headlines

* Record (cool) July 16 in St. Cloud - high only 66 F. More records likely today, including the Twin Cities, where the predicted high is 64. The record for the coolest high on July 17 at MSP is 66, set in 1939. We should break it.

* Minnesota waking up to rare July wind chill - feels like 40s out there this morning.

* Gray, almost October-like Friday, temperatures hold in the 60s (50s far north). More records may be set for the coolest July 17 on record.

* Saturday clearing trend as winds finally ease; Sunday shapes up to be the warmer day of the weekend.

* Moderate drought expands to St. Cloud and much of central Minnesota, severe drought now covers more than 5% of Minnesota.

* Tornado that hit Swift Falls rated EF-2 by local National Weather Service.

* Lake water levels down as much as 4-5 feet east of the Twin Cities.

* Next 90? Last day or two of July.



I have this strange, inexplicable urge to rake leaves, toss a football, order a Halloween costume (even scarier than my usual outfit). Better yet let me hit SNOOZE on my alarm clock, curl up into the fetal position and dream of warm, sultry, steamy weather - July the way it's SUPPOSED to be. This is a cruel joke. The calendar is shouting mid July, but the atmosphere floating over Minnesota will be shouting October (!) much of today, with raw, ragged clouds, gusty winds and "highs" stunted in the 60s, even some 50s up north. Highs! Yesterday St. Cloud set a record for the coolest July 16 since records were first kept back in 1894 (only 66 meager degrees - that would be a typical low temperature this time of year). The same thing may happen today. Here, courtesy of the National Weather Service, are the old records for "coolest July 17".

MORE RECORD COLD HIGH TEMPERATURES ARE POSSIBLE ACROSS THE REGION ON FRIDAY. HERE ARE THE COLDEST HIGH TEMPERATURES RECORDED AT ST CLOUD...THE TWIN CITIES...AND EAU CLAIRE ON JULY 17TH:

ST CLOUD 66 DEGREES IN 1927

TWIN CITIES 66 DEGREES IN 1939

EAU CLAIRE 68 DEGREES IN 1939


Predicted Wind Chill at 7 am this morning. I hope to never have to show this graphic again during June, July or August, but if you're heading out early you may want to consider a jacket or sweatshirt. It will FEEL like 30s over about the northern third of Minnesota during the morning hours!

Clouds will prevail much of today, the result of high relative humidity in the lowest few thousand feet of the atmosphere, and unusually cold air aloft. The sun may peek through from time to time, but clouds will dominate, winds gust as high as 25-30 mph - you'll swear you've been transported to early October. It will make Sunday's 80-degree sunshine even sweeter.

Predicted Relative Humidity at 1 pm today. The bright blue-shaded areas are regions of relative humidity > 90%, where you would expect to find broken to overcast conditions. The sun will be shining across the Dakotas, drier air which will finally break up our stubborn stratocumulus clouds Saturday morning.

Forecast Rainfall from 1 pm to 7 pm today. Clouds may be thick enough to leak a few light showers and sprinkles over the Minnesota Arrowhead. A sprinkle or two may reach St. Cloud, even the Twin Cities, but no puddles are expected close to home.

Predicted Temperature at 7 pm Saturday evening. There is a light at the end of our cold, gray tunnel. A weak bubble of Canadian high pressure will break up the clouds early Saturday, with enough blue sky for highs in the low 70s Saturday afternoon. Winds will ease too, blowing under 10-15 mph from the northwest. Saturday will be a BIG step in the right direction.

Rainfall prediction for Saturday, 1 pm to 7 pm. Showers are forecast to linger over Wisconsin and the Chicago area, but a dry sky is expected across all of Minnesota Saturday afternoon, so plan those outdoor events with confidence. It will still be a bit on the cool side for a dip in the lake, but in the sun it should feel great out there.

Next week will feel more like summer with a streak of highs in the upper 70s to low 80s, closer to average for mid July. Some rain and a few storms may drift into town late Monday and Monday night, followed by a series of weak cool frontal passages. The "polar vortex", a massive swirl of unusually cold air which should be swirling over the Arctic Circle has been displaced 500 miles farther south than usual, forcing the jet stream (and subsequent cool fronts) to detour way south, pushing a family of cool fronts across the northern tier states. This very stubborn, very persistent pattern will linger into much of next week, keeping us cooler than average, but NOT as chilly as today. You want real heat? You may have to wait until the last day or two of July, when the long-range GFS model is hinting at 90 degree heat across central and southern Minnesota. I know - I'll believe it when I see it.

Drought Monitor. I was surprised to see moderate drought conditions nearly double in size in just the last week, now impacting nearly 30% of Minnesota. Severe drought conditions extend from the Twin Cities on north, right up the St. Croix River Valley. The lack of rain (east metro is running a 6-8" rainfall deficit since April 1) is starting to have a significant impact on not only farming, but lake water levels. Check out the difference in lake levels from Minnetonka (Hennepin County) to White Bear Lake (Ramsey County).

Lake Minnetonka Water Level. It appears that the biggest lake in Hennepin County is down a little more than 12" from it's long-term average.
White Bear Lake Water Level. The drought is more severe north/east of St. Paul. Taking a close look at this graph it appears White Bear is down at least 4-5 feet from normal levels!

To check out water levels, quality (and how safe it is to eat fish) click here to see updated information from the Minnesota DNR.

While we're at it, Conservation Minnesota has an excellent site that provides a wealth of information about Minnesota lakes, everything you need to know. Click here to see checkmylake.org.



NWS Chanhassen Doppler Radar reflectivity image of the storm which had a tornado near Swift Falls at the time. To the southeast, one will note the more disorganized storm which 20 minutes later rapidly evolved into the tornado producer near Spicer.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
513 PM CDT THU JUL 16 2009
...DAMAGE SURVEY RESULTS FROM THE JULY 14TH TORNADOES...
NATIONAL WEATHER SERVICE PERSONNEL FROM THE CHANHASSEN FORECAST
OFFICE CONDUCTED A DAMAGE ASSESSMENT IN THE SWIFT FALLS AND SPICER
MINNESOTA AREAS ON WEDNESDAY.
...SWIFT FALLS AREA TORNADO...
THE MAXIMUM INTENSITY TORNADO DAMAGE IN THE SWIFT FALLS AREA WAS
FOUND TO BE EF-2 WITH ESTIMATED WINDS BETWEEN 110 AND 119 MPH. THERE
WERE NO REPORTED FATALITIES OR INJURIES WITH THIS TORNADO. THE
ENTIRE PATH LENGTH WAS APPROXIMATELY NINE MILES...WITH A MAXIMUM
WIDTH OF 350 YARDS. THE TWISTER BEGAN ABOUT THREE MILES SOUTHWEST OF
SWIFT FALLS IN FAR NORTHERN SWIFT COUNTY...TRACKED NORTHEAST THROUGH
SWIFT FALLS...AND ENDED ON THE SHORE OR POSSIBLY OVER SCANDINAVIAN
LAKE IN FAR SOUTHERN POPE COUNTY. THE MOST SIGNIFICANT DAMAGE WAS
ALONG THE FIRST ONE MILE OF THE TORNADO PATH...WHERE TWO LARGE
TURKEY BARNS WERE COMPLETELY DESTROYED. THE NEXT FIVE MILES OF THE
TRACK WERE HIGHLIGHTED BY EF-1 DAMAGE WITH WINDS BETWEEN 85 AND
100 MPH...WHICH INCLUDED SIGNIFICANT TREE DAMAGE IN SWIFT FALLS.
THE TORNADO PRODUCED EF-1 DAMAGE TO TWO RESIDENCES...DESTROYING
TWO GARAGES AND OTHER OUTBUILDINGS WITH MINOR ROOF DAMAGE TO THEIR
HOMES. THE TORNADO PRODUCED MAINLY MINOR CROP AND TREE DAMAGE OVER
THE LAST FOUR MILES OF ITS PATH. TOUCHDOWN TIME APPEARED TO BE
4:21 PM WITH AN END TIME AROUND 4:37 PM...FOR AN AVERAGE MOVEMENT
OF AROUND 34 MPH.



...SPICER AREA TORNADO AND WIND DAMAGE...
THE TORNADO THAT STRUCK SPICER IN CENTRAL KANDIYOHI COUNTY HAD A
MAXIMUM INTENSITY OF EF-1 DAMAGE WITH WINDS ESTIMATED BETWEEN 100
AND 109 MPH. THERE WERE NO REPORTED FATALITIES OR INJURIES WITH
THIS TORNADO. THE TRACK WAS APPROXIMATELY SIX AND A HALF
MILES...WITH A MAXIMUM WIDTH OF 250 YARDS. THE BEGINNING OF THE
PATH WAS TWO MILES SOUTHWEST OF SPICER. IT TRACKED NORTHEAST
THROUGH SPICER...INCLUDING ALONG THE SOUTHERN SHORE OF GREEN
LAKE...EMERGED OVER THE LAKE...AND FADED SOON AFTER MOVING BACK
OVER LAND ABOUT THREE-QUARTERS OF A MILE SOUTH OF THE INLET FROM
CALHOUN LAKE. THE MOST SIGNIFICANT DAMAGE WAS ROUGHLY ONE TO TWO
MILES INTO THE TORNADO PATH...OR JUST SOUTHWEST OF SPICER...WHERE
A PORTION OF A HOME WAS DAMAGED ALONG WITH SIGNIFICANT TREE
DAMAGE. WITHIN SPICER...THE TORNADO CONTINUED TO PRODUCE EF-1
DAMAGE BREAKING WINDOWS IN DOZENS OF VEHICLES ACROSS THE GREEN
LAKE MALL PARKING LOT AND UPLIFTING A LARGE PART OF A HOUSE AND
GARAGE ROOF. THE FINAL FOUR MILES OF THE TORNADO TRACK HAD MINOR
EF-0 TREE AND SHINGLE DAMAGE. TOUCHDOWN TIME APPEARED TO BE
4:41 PM WITH AN END TIME OF 4:53 PM...FOR AN AVERAGE MOVEMENT OF
AROUND 33 MPH.
APPROXIMATELY ONE HALF MILE SOUTH OF THE SPICER TORNADO WAS
LOCALIZED BUT EXTENSIVE TREE DAMAGE. THE NATURE...LOCATION...AND
TIMING OF THIS DAMAGE WAS DETERMINED TO BE STRAIGHT-LINE WINDS
FROM THE REAR FLANK DOWNDRAFT OF THIS TORNADIC THUNDERSTORM. THE
DAMAGE OCCURRED ROUGHLY AT THE SAME TIME THE TORNADO WAS
DISSIPATING. ESTIMATED WINDS WERE BETWEEN 90 AND 100 MPH. SUCH A
PHENOMENA CAN OCCUR WITH STRONGLY ROTATING THUNDERSTORMS AND CAN
OFTEN HAPPEN IN THE LATTER PERIOD OF THE TORNADO LIFE CYCLE.
FOR A LINK TO THE TORNADO RATING SCALE...OR ENHANCED FUJITA
SCALE...VISIT HTTP://WWW.SPC.NOAA.GOV/EFSCALE

(For a terrific summary of Tuesday's tornado outbreak click here).

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