Rare Lake Effect event setting up for Lake MI

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PurdueWx80
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Rare Lake Effect event setting up for Lake MI

#1 Postby PurdueWx80 » Sat Dec 18, 2004 8:45 pm

Hey folks - I've been getting pretty excited about the setup for the LES event tomorrow. As you all know, Lake MI is oriented N-S and is rather long. The lake is still near 40-45 deg F at the surface, while air at 850 mb will be near -10F. That leads to superadiabatic lapse rates from the sfc to 850, causing extreme instability, which increases the chance of heavy snowfall rates that may approach 2-3" per hour (and perhaps thunder). What's strange is that the flow from the surface to 850 will become oriented in a nearly pure N-S direction, allowing the winds to pick up a ton of moisture and heat from the lake. It's pretty rare to get pure N-S flow over the lake for an exteneded period of time, but when it happens a major event can occur. Anyway, Lafayette, where I am now, almost never gets LES - in fact, in my 6+ years here we have never had more than a few quick snow showers (just a dusting basically). Tomorrow will be a different story given winds of 30-45 mph (allowing one primary convergent band to setup, therby leading to a long line of heavy snow showers). I was concerned that areas this far south (a good 75-100 miles south of the Lake) would see decent snow, and now the Indy NWS has caught on.

Updated AFD:
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
815 PM EST SAT DEC 18 2004

.DISCUSSION...

UPDATE...

INTENSE UPPER TROUGH DIGGING INTO THE OHIO VALLEY THIS EVENING.
STRONG DYNAMIC LIFT AHEAD OF TROUGH AXIS WILL LEAD TO AREA OF LIGHT
SNOW ACROSS THE NORTHEAST HALF OF THE CWA THROUGH 09-12Z TONIGHT.
THEREAFTER, 00Z 850MB TEMPS OF -25C WILL OVERSPREAD LK MI. LK TEMPS
REMAIN IN THE 42-45F RANGE. THE COMBINATION OF THE TWO WILL LEAD TO
EXTREME INSTABILITY IN THE LOWEST 5KFT. INVERSION OFF OF BUFKIT
REMAINS 5-7KFT INTO MID MORNING SUN WHILE LATEST RUC/ETA SHOW
SFC-850MB WINDS BECOMING MORE FAVORABLE FOR BANDS TO POTENTIALLY
IMPACT AREAS A BIT FURTHER WEST INTO TIPPECANOE AND EVEN
WARREN/FOUNTAIN COUNTY EARLY SUN. WILL UPDATE TO INCREASE SNOW
AMOUNTS WITH 1 TO 3 INCHES A GOOD BET SOMEWHERE IN THE
TIPPECANOE/CARROLL/CLINTON/HOWARD AREA. SNOW BAND SHOULD EASE AFTER
21Z SUN AS 850MB WINDS DECREASE. WILL ALSO INCREASE WIND SPEEDS IN
GRIDS WHICH SHOULD TAKE MOST OF THE AREA DOWN INTO THE 0 TO MINUS 5
WIND CHILL RANGE BY SUNRISE.


Areas just to the north, closer to the Lake have lake effect warnings and advisories for up to a foot, but they are now calling for 1-3" here after saying most areas would only see an inch. Some of the higher resolution mesoscale models show a vortex forming over the Lake, which is actually pretty cool. We will probably see a lake-induced surface low develop over many of the Lakes tomorrow - check out the visible loops for signs of them. Of concern also, especially near the Lakes where snow is heaviest, will be the winds, which the RUC shows being as high as 40-45 kt, so with temps in the teens or single digits, wind chills will be well below zero. It's not gonna be fun for folks traveling up I-65 to Chicago, and in fact, I'm assuming it will be shut down at a point with heavy snow right over the interstate and visibilities near zero. I'm getting excited about this if you can't tell, so in between a marathon session of watching all 3 Lord of the Rings movies tomorrow (yes, the extended versions!), I'll be on my iBook w/ wireless checking it all out! Sounds like the perfect day to be inside. I'll let y'all know how much we end up with, but I'm guessing now it'll be 2-4" here. That'll also increase the chances of us going to -10F or colder on Monday morning!!
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#2 Postby ssom04 » Sat Dec 18, 2004 9:02 pm

I always wanted to be in a les storm but never had the chance too. But once there was snow showers coming from Lake superior in duluth nothing huge. I hope you get dumped! As for minnesota winter sucks! unless you live in the arrowhead. Its that el nino crap. This sunday maybe a inch before temps rise from 11 degrees in the evening to near 30 by 2 am and the freezing rain comes on in........... depressing
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#3 Postby PurdueWx80 » Sun Dec 19, 2004 2:15 pm

Well, the air mass that advected in was 5-10 degrees cooler (and drier) than expected at the surface, so the band hasn't made it as far inland as some had imagined. We have about in inch from the synoptic snow last night - but in checking out new totals in far northern IN, I see that this storm is overachieving. It makes sense since temps are near 10 at the surface, meaning snow/liquid ratios are near 30:1.

Code: Select all

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE NORTHERN INDIANA
130 PM EST SUN DEC 19 2004


FOLLOWING ARE SOME SNOWFALL TOTALS THROUGH AROUND 1PM EST NOON CST.

NORTHERN INDIANA...


CITY                     COUNTY      STATE      SNOW TOTAL

ROLLING PRAIRIE          LAPORTE      IN           4.8
NORTH LIBERTY            ST. JOSEPH   IN           1.5
MICHIGAN CITY            LAPORTE      IN           8.0
MICHIGAN CITY            LAPORTE      IN          15.0
ROCHESTER                FULTON       IN           0.5

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
1215 PM CST SUN DEC 19 2004

A LAKE EFFECT SNOW EVENT CONTINUES ACROSS NORTHWEST INDIANA THIS
AFTERNOON. HERE ARE SOME SNOWFALL REPORTS RECEIVED THROUGH 12 PM
CST. THIS REPORT INCLUDES MOSTLY COOPERATIVE OBSERVERS...CHICAGO
AREA SNOWFALL TEAM...HAM RADIO OPERATORS...AND TRAINED SPOTTERS.
MORE REPORTS WILL BE GATHERED THROUGHOUT THE DAY AND UPDATED.


LOCATION                        SNOWFALL AMOUNTS

NORTHWEST INDIANA

CHESTERTON......................5.5
WHEATFIELD......................5.5
HEBRON..........................6.0
1 MILE E OF CROWN POINT.........6.0
5 MILES N-NE VALPARAISO.........7.0
VALPARAISO......................8.3
MICHIGAN CITY...................15.0
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#4 Postby PurdueWx80 » Sun Dec 19, 2004 4:09 pm

Michigan city up to 19" now...expecting over 2 feet total by tomorrow morning. Incredible!!! Only a few miles away hardly anything has fallen.

Code: Select all

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE NORTHERN INDIANA
342 PM EST SUN DEC 19 2004


THE FOLLOWING ARE MAXIMUM SNOW DEPTHS SO FAR TODAY
THROUGH 330 PM EST...

SOUTHERN LOWER MICHIGAN...


CITY            COUNTY      MAX.DEPTH     TIME OF REPORT

BENTON HARBOR   BERRIEN       7.8           0745
BUCHANAN        BERRIEN       4.0           0800
EAU CLAIRE      BERRIEN       5.3           0800
BERRIEN SPRINGS BERRIEN       6.0           0830


NORTHERN INDIANA...

SOUTH BEND      ST. JOSEPH    7.0           0700
NEW CARLISLE    ST. JOSEPH    3.0           0810
ROLLING PRAIRIE LAPORTE       4.8           1115
MICHIGAN CITY   LAPORTE      19.0           1415


$$
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#5 Postby coriolis » Sun Dec 19, 2004 4:19 pm

That's awesome, Purdue, I looked at the radar and there's just one steak of snow running all the way down lake Michigan. I don't understand how that happens, but it's a unique phenomenon. We get those kind of streaks off lake Erie a lot, but by the time it gets to me, it's just a series of cloud streaks, making the sky look striped. I got another one in my thread, that extends all the way to Pittsburgh.
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#6 Postby PurdueWx80 » Sun Dec 19, 2004 4:49 pm

coriolis wrote:That's awesome, Purdue, I looked at the radar and there's just one steak of snow running all the way down lake Michigan. I don't understand how that happens, but it's a unique phenomenon. We get those kind of streaks off lake Erie a lot, but by the time it gets to me, it's just a series of cloud streaks, making the sky look striped. I got another one in my thread, that extends all the way to Pittsburgh.


Lake effect snow is so amazing, I do remember seeing these a lot off the 2 easternmost Lakes when the flow is W or WSW. I did see the streak reaching all the way to Pittsburgh...it's so narrow! Basically, the very warm water and extremely cold air above it causes the air to rise rapidly, so air has to come into replace what goes up and you get very strong convergence. It manifests itself as very heavy precipitation that is very shallow when compared to summertime convection and storms. The 1 long strip has to do with the shape of the Lake, many times there will be several weaker bands when the flow is WNW or NW over Lake Michigan.
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#7 Postby nystate » Sun Dec 19, 2004 5:49 pm

Speaking of the streamers, last year we had a streamer here that was very intense and nearly stationary. Snowfall rates of up to 8"/hour, with Parish, NY picking up 86" from the LES storm before it was over. Places outside the belt got next to nothing. Incredible how LES works...

Enjoy the snow!
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