Updraft Category Archive: Forecast models

Snow likely southeast Minnesota Saturday

Posted at 6:37 AM on December 2, 2011 by Craig Edwards
Filed under: Forecast models, Snow, Winter storms

The changes in the jet stream pattern appear to be on track to push moisture into southeast Minnesota later tonight through Satuday evening. As the moisture meets up with the colder temperatures, accumulating snow is likely to occur from Austin through Dexter, Wabasha and on into Black River Falls, Wisconsin. Snowfall could be four inches or more in the region.

At this time, the continuity of the model data is holding firm in keeping the Twin Cities metro on the fringe of the snow band. We'll track the developing precipitation on radar as the system advances toward Iowa and Minnesota later tonight.

Confidence has heightened on the potential for significant snowfall and a Winter Storm Watch has been issued for portions of southeast Minnesota.

Blue shading highlights the Winter Storm Watch for Satuday. See more details from the La Crosse NWS Office.

Here is NOAA's Environmental Prediction Center's probability of snowfall of greater than four inches.

The forecast map from the NAM for 6PM Saturday places the surface low pressure in a good spot for snow over southeast MInnesota. The pressure gradient is not strong, thus the winds should remain on the order of 10 to 15 mph.

In case you missed it, the temperature dropped to four degrees below zero last evening in Ely before recovering to near ten degrees this morning.

Statewide it looks to be a quiet day with seasonal temperatures. Traveling southeast on Saturday from the Twin Cities? Keep tuned for updated weather forecasts.
CE

Crafting a forecast with the tools at hand

Posted at 3:34 PM on December 1, 2011 by Craig Edwards (1 Comments)
Filed under: Cold, Forecast models

It's times like these where a meteorologist gets pumped about the profession. Sorting through the computer models, matching the satellite data with previous computer model output and tracking surface weather make the job challenging and sometimes even rewarding.

Here's the infrared satellite imagery at mid afternoon. The large scale circulation over the southwest corner of the US appears to be more tame than the weather reported from southern California to Colorado. Winds have gusted from 60 to 80 miles an hour from near Los Angeles to Las Vegas in the past eighteen hours. The national news networks are delivering the details of this savage weather.

Meanwhile another surge of cold air is sweeping through Albert, tracking toward the Dakotas and Minnesota as indicated in the enhanced (red) cloud tops.

These two separate systems are likely to meet up from Minnesota to Missouri on Saturday.

Here's an image of the mid level jet stream from noon today. The wind field is approximately 18k feet.

The closed circulation of the upper low stands out over southern California and Arizona. Wicked winds have been induced at the surface as a result of the topography and the atmospheric dynamics of this system.

By noon on Saturday, as shown by the NAM, the low in the southwest has weakened and continues to track east, but no longer a closed circulation. At the same time a trough has been craved out in North Dakota. These two forces of nature will combine to create the problematic weather in southeast Minnesota.

The reflection of weather on the surface is what television weathercasters typically deliver to the viewers to keep the meteorology simple. But significant precipitation is induced by factors at cloud level of 5K and greater.

Here's the consensus track of the surface low from NOAA for the next couple of days. Indeed a favorable track for snow in our neck of the woods, but not a particularly deep center of low pressure.

Put this altogether and it still targets the best chance for accumulating snow over southeast Minnesota. NOAA's Environmental Prediction center indicates the most likely area for four or more inches of accumulation on Saturday.

Want the condensed version of this story? See this snapshot from the Chanhassen NWS Office.

Tune in tomorrow morning for details of your weekend weather forecast.
CE

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Timing and location, sorting out the chance for showers

Posted at 6:46 AM on August 11, 2011 by Craig Edwards
Filed under: Forecast models, Rainfall

From the IR satellite image this morning you can see the general quite and rather comfortable temperatures depicted across the northern tier of the continental USA. Meanwhile a couple of clusters of thunderstorms were evident from the Texas panhandle to northern Mississippi (shown by the color red for colder cloud tops).

Our next rain producer is in the process of taking shape in Montana. The evolution of the mid level spin in the atmosphere and its track eastward will determine the timing and location of the most significant rainfall in the upper Midwest.

In candor, I spied some spotty showers on radar yesterday late afternoon in northeast Minnesota and northwest Wisconsin. Most of Minnesota enjoyed delightful temperatures and plentiful sunshine. We sometimes refer to these random, not well forecast showers as rogue showers.

One more day of sunshine and comfortable temperatures is on tap for your Thursday. Clouds thichen west to east later today and overnight. The most likely region of showers during the darkness hours is over western Minnesota, where a half inch of rain may accumulate in a few places.

Here's a graphic from the GFS of the model's output of rainfall accumulation for Friday evening. The North American Model output (not shown) is not as generous with the rain in southeast Minnesota, where the GFS prints out over an inch near the Iowa border.

By profession, meteorologists are expected to parse out the model information and make a forecast. So there will be differing forecasts on the timing and probability of wetness in your location in the next 48 hours. My best guess is the rain chances are highest in Minnesota from midnight tonight to daybreak on Saturday.

Clouds on Friday may hold maximum temperatures in the 70s over much of the region. Central and northern Minnesota's Lake Country should see at least partial sunshine Saturday afternoon. Sunshine should dominate statewide on Sunday with a continuation of temperatures near or slightly below normal.

As a broad snapshot of national rainfall potential in the next seventy-two hours, here's the forecast of rain accumulation through Friday night from NOAA meteorologist. Of interest here is a relative minimum total expected where the GFS indicates an inch of rain in northeast Iowa.

Hope your home gardens are doing well.
CE

Taste of back-to-school weather

Posted at 6:47 AM on August 8, 2011 by Craig Edwards (1 Comments)
Filed under: Forecast models, Hurricanes, Rainfall

A cool front will sweep through the upper Midwest today and tonight bringing the chance for showers and thunderstorms. After the front passes temperatures will fall to readings more typical of late August. Expect brisk northwest winds as well on Tuesday.

Here's the short term RUC model of surface temperatures, pressure pattern and winds for late afternoon. Note the region of sizzling hot temperatures in Kansas andOklahoma, extending into Texas.

Rainfall with this passing cool front will not be overly generous. NOAA's Envirnomental Predication Center paints this graphic of rainfall potential for the next twenty-four hours.

Texas continues to remain in severe drought. Some large areas of the Lone Star State are in exceptional drought.

With regard to tropical storm activity things are quiet for the moment. The peak of the hurricane season is approaching.

Historical record of seasonal tropical storms in the Atlantic from the Hurricane Center.

Early morning temperatures on Wednesday may be the coolest since the Twin Cities dipped below 60 degrees and recorded a low of 58 on June 28th. Check out this forecast for temperatures on Wednesday morning from the WRF model.

On this date in 2010 the Twin Cities Internationl Airport reached 96 degrees to tie the record high for August 8th set in 1894, repeated in 1914. The normal max/min for August 8th in the Twin Cities 82/63.

In case you missed it, Roseau experienced temperatures in the middle 60s for much of Saturday, with early Sunday morning temperatures in the upper 40s.

A rather isolated strong thunderstorm produced golf ball sized hail near Young America in Carver County on Saturday evening.
CE

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Looking way ahead

Posted at 6:46 AM on November 16, 2010 by Craig Edwards
Filed under: Forecast models

More typical November weather has arrived. Through the next week or so there will be pushes of somewhat milder air and instrusions of colder air right where one would expect it to occur, over the upper Midwest. The decreasing hours of daylight are positioning the atmosphere to a battle ground that transitions from autumn to winter.

If you recall, Paul Huttner posted on this blog on October 29th that the long range models indicated a potential snow storm on the 13th of November. The models toyed with the meteorologists for a period of time, before finally locking in and maintaining the confidence that snow was likely in Minnesota last Saturday.

Well let's try this long range outlook stuff again. Here's an image from the GFS model of the surface pressure pattern and two meter temperatures for 6am Thanksgiving morning. That magenta color you see over the Dakotas paints sub-zero temperatures.

For now there will be spritzes of precipitation over southern Minnesota today. Overcast skies are likely to keep the maximum temperature from reaching forty, the normal daily high, in the Twin Cities.
CE

Forecast: Roller coaster temps

Posted at 8:46 AM on November 3, 2010 by Paul Huttner
Filed under: Astronomy, Forecast models

Get ready for a temperature roller coaster ride the next few days.

While we were busy election watching, a cool front slipped through Minnesota overnight. You'll notice a decidedly cooler breeze by late today and tonight in Minnesota.

Temperatures will hang in the 40s for highs on Thursday, and then begin to recover into the 50s this weekend and maybe push 60 by Sunday in southern Minnesota. This looks to be the best (and last?) weekend to get those last few leaves up, so take advantage of the relatively nice weather!

Forecast models & rapid changes:

Watching the forecast models this year is a little like watching election polls. They can turn on a dime, and there is little consistency from day to day.

Often models will advertise big temperature swings in November, only to flip flop on the trend a day later. There is often little "run-to run" consistency this time of year.

The movement and evolution of weather systems speeds up dramatically in late fall and winter. (Can you say "Octobomb?") Numerical forecast models often have a difficult time keeping up with rapid changes. This means forecast accuracy can fall quickly as you move out in time these days.

Meteorologists definitely earn their keep as we head into winter. It is important this time of year to beware "model advertised" of big radical temperature shifts, and to keep an eye out for phantom snow storms that can pop up seemingly out of nowhere this time of year in the Upper Midwest.

Snow cover lagging up north:

We don't see our 1st inch of snowfall in the metro on average until November 18th, but overall North American snow cover is relatively thin "upstream" in northwest Canada. This will take some of the punch out of southbound cold fronts until snow cover fills in later in the season.

The hemispheric jet stream pattern has locked up a cold pool of air over the North Pacific. This usually means milder than average air in the northern USA, and this has been the case so far this fall.

There are signs colder air may begin to filter south later next week. Stay tuned.

Sky show:

The auroras are back over Norway these days. Check out the amazing images from spaceweather.com.

PH