Updraft: December 21, 2009 Archive

Forecast: Major Christmas Storm

Posted at 8:22 AM on December 21, 2009 by Paul Huttner (11 Comments)

NOAA SREF forecast model ensemble paints heavy snow moving into Minnesota by Christmas Eve.

You may be dreaming of a White Christmas, but maybe not this white.

All signs today point to a major winter storm tracking into Minnesota for Christmas Eve and Christmas day. If you are planning travel anywhere in the Upper Midwest by car of air later this week, be prepared for heavy snow and major winter storm conditions.

It is still early in the forecast process for major winter storms, but here's what I see this morning.

-A potent upper and surface low pressure system will wind up in Texas Wednesday, then eject northward toward Minnesota.

-The track of this low will start near the Gulf of Mexico. We call these storms "Gulf Storms" because of the track and the fact that they pull in deep Gulf moisture. These can be some of the heaviest and wettest snows for Minnesota.

-The storm looks as if it will move very slowly, meaning a potential long duration snowfall event of 48 to 60 hours.

-It appears now that snow could begin anywhere from late Wednesday into early Christmas Eve morning.

-The heaviest snow may be during Christmas Eve and Christmas Day.

-Snowfall could last until Saturday in parts of the area.

-The snow could mix with freezing rain and sleet in eastern Iowa and southwest Wisconsin.

It is too early to pinpoint snowfall amounts, but it should suffice to sat that many areas could get slammed with over a foot of snow with this storm. There could be much higher totals in some areas. The snow will combine with wind in open areas making travel difficult to impossible Christmas Eve and Christmas Day.

If you have travel plans Thursday into Saturday, at this point I would encourage you to consider travelling Wednesday or Sunday instead.

I'll keep updating things this week as the new forecast model runs come in.

As we say in the weather biz...stay tuned.

PH

(11 Comments)

Update: Major Storm Still On Track

Posted at 4:31 PM on December 21, 2009 by Paul Huttner (6 Comments)

Twin Cities NWS weather story highlights potential heavy snow area this week.

This could be the "big one."

All indications are that a major winter storm is still on track to bring heavy snow, ice and major winter storm conditions to the Upper Midwest this week.

Though it is still a little too early in the forecast process to pinpoint specifics, the big picture regarding holiday travel is increasingly clear. Travel in the Upper Midwest will be extremely difficult from Wednesday evening right into Saturday.

The best travel days appear to be Tuesday, the first half of Wednesday, and Sunday.

Here are some updated trends this afternoon.

-Winter Storm Watches have been posted form much of southern Minnesota and surrounding areas from Wednesday evening through Friday afternoon.

-Forecast models are clustering around a surface low track from near Dallas Wednesday evening, to just east of Kansas City early Friday, then crawling slowly toward the La Crosse area by early Saturday. This is a favored track for heavy snowfall in the metro.

SREF model ensemble 12 hour snowfall paints heavy snow for southern Minnesota on Christmas Eve. Additional snowfall may accumulate into Saturday.

-It appears snow and ice will begin in Kansas, Nebraska and Iowa Tuesday. Snow will likely begin in the Twin Cities by late afternoon or just after dark Wednesday.

-The slow moving nature of the storm could produce 48 to 60 hours of nearly continuous snowfall. Snow may not end in the Twin Cities until noon Saturday.

-The latest model trends bring the surface and upper low far enough west to wrap in some warmer air into Wisconsin and southeast Minnesota. This could mean a mix of freezing rain and sleet, which would reduce snowfall totals there, but still create hazardous driving conditions.

-As for snowfall totals, it's too early to forecast snowfall amounts for any one area until the track and intensity of the storm become a little more clear. It's reasonable to suggest though, that the long duration, deep moisture and intensity of this storm may produce prolific snowfall totals of 12" to 18"+. Some totals over 20" are not out of the question somewhere in southern Minnesota, and maybe in the Twin Cities.

I'll put out a specific forecast for snowfall totals probably late Tuesday or early Wednesday. In the mean time the effect is the same. If you can travel Tuesday or early Wednesday, and on Sunday, go for it. If you're fortunate enough to just sit inside and watch it snow... Hallelujah!

Here are some links to monitor the developing storm:

-Twin Cities NWS
-Sioux Falls NWS
-Des Moines NWS
-La Crosse NWS
-Duluth NWS
-SREF model ensembles
-Latest Midwest surface map
-Twin Cities NWS forecast discussion
-Twin Cities radar loop

PH

(6 Comments)