Saturday, December 26, 2009

Just A Little More...

Our cut-off low pressure system continues to rotate above the northern plains and western great lakes regions, and is making sure it squeezes out as much moisture as possible before it leaves.  Scattered snow showers are rotating across portions of the Dakotas, Minnesota, Nebraska and Iowa at this hour, providing anywhere from a dusting to upwards of 2-3 inches on the ground in heavier bands.  This snow will just be a little top-off by this system before finally leaving the plains...

We'll be left in a cool air mass, with temperatures in the teens and 20s across the northern plains on Sunday.  The Dakotas and northwest Minnesota will see a cool down into the lower 10s for Monday and Tuesday while the remainder of the northern plains will keep high in the teens and 20s.  Lows will have a greater variance, from the single digits below zero the the lower teens from ND to southern Iowa on Sunday night.  Below zero temperatures will be widespread to all but southern Iowa on Monday night and from the teens to near zero from southern Iowa to the Canadian border on Tuesday night ahead of our next clipper storm system.

Our next storm system will not likely bring much in the way of precipitation, but will bring in some reinforced cold air.  Temperatures for the remainder of the week will be below normal with below zero temperatures across much of the northern plains.  More details on this mid-week clipper in the next update...

Winter Storm: Dec. 23-25 Overview

The Christmas Snowstorm/Blizzard of 2009 has came to an end across most of the plains, with some lingering snow left over the Great Lakes region and the far eastern plains states. Widespread blizzard conditions creating major travel delays and cancellations with airport and road closures. These conditions along with a mix of sleet, ice, and snow created power outages across many areas and even more travel concerns. Other areas of the plains were warm enough to escape the winter storm, but saw flooding rains as frozen ground created troublesome run-off.

The Des Moines NWS has issued their event snowfall map for the state of Iowa, which shows a good gradient of snowfall across the state. Keep in mind that there is several reports of greater than 12" in northwest Iowa where isolated amounts of 18-21" have been reported. I've included links to several NWS website stories that have event totals in lists, or in both lists and graphical format below.  I may do another post if I find more NWS sites that do an event summary on the event similar to ones that a few others have done.


Des Moines NWS Map

Omaha NWS Map & List

Sioux Falls NWS List

Kansas City NWS Summary & Maps

Aberdeen NWS List

LaCrosse NWS Summary & List

Friday, December 25, 2009

Winter Storm: Dec. 23-25 Update #6

The Christmas Blizzard and Winter Storm of 2009 has taken its' toll thus far with several roads and interstates becoming closed last evening and continued to be closed this morning.  Much of western Iowa, eastern Dakotas/Nebraska, and southern Minnesota and feeling the brunt of the snow currently.  Expect the snow and winds to continue through the day, making travel near-impossible if not completely impossible.  Refer to the previous post for an updating map on current snowfall totals.  Below is the latest Sioux Falls NWS weather story displaying their current warnings they have issued and the latest expected snowfall forecasts.





Sorry for the short update, but after all it is Christmas morning! Enjoy it inside and don't risk the travel today as conditions are very unforgiving.

Thursday, December 24, 2009

Winter Storm: Dec. 23-25 Update #5

The Christmas Blizzard of 2009 is well underway with the expansion of blizzard warnings to include parts of Iowa, Nebraska, South Dakota and other areas.  Interstates and other major highways are now being closed by the DOT's and other areas are advising no travel.  With winds on the increase throughout the night expect conditions to continue to worsen and remain hazardous through Christmas day.  The combination of ice, snow, and strong winds may also be creating some power outages for the areas affected.

The map below will update automatically throughout the night and Christmas day with the latest snowfall totals, enjoy your Christmas day!

Map removed due to being outdated.

Winter Storm: Dec. 23-25 Update #4

Our first round of snow across the northern plains has came to an end, and we are now looking towards a digging trough in the western plains and its' associated low pressure system that should strengthen and create blizzard or near-blizzard conditions across a large part of the northern plains.  Both the northern and southern streams of the jets will have ample support for a low pressure system and result in rapid intensification of the 500mb low creating a large closed low across the northern high plains.  This will aid in pulling the intensifying surface low from the Mississippi valley region back westward towards the northern plains.  This will prolong the snowfall for much of the plains, and also results in an increased pressure gradient leading towards are high winds expected tonight through Friday.

For today we'll see some scattered snow showers and mixed precipitation across the state of Iowa and adjacent areas, with little accumulations for most areas.  This may give roadway crews time to clear the roads somewhat and make travel a little less hazardous.  However, conditions will deteriorate very quickly this evening as moderate to heavy snow begins to fall and winds continue to increase.  Models continue to forecast the heaviest snowfall across western Iowa, with the potential for 8-12" or more during the overnight hours tonight with snow continue through Christmas day.  Snowfall totals still look to range in the 16-18" with isolated higher amounts throughout western Iowa, Minnesota, the eastern Dakotas and nearby areas.

While afternoon and evening travel may not appear hazardous with the lack of precipitation falling, keep in mind that conditions will deteriorate rapidly this evening as our next storm system begins to impact the area.  Moderate to heavy snowfall will fall throughout the nighttime hours and continue through the day on Christmas.  Here is some of the latest snowfall totals for the past 24 hours at Iowa cooperative observer stations (this should fill in with all of the reports as they are received today):




Wednesday, December 23, 2009

Winter Storm: Dec. 23-25 Update #3

Some hefty snow falling across Iowa currently, with some very large flakes being reported in many areas.  Thus far I currently measure 3.25" of snow, with snow currently falling at a 1"/hour rate.  There is some fairly hefty snow falling across parts of the state currently, with 2"/hour or heavier snow rates likely in the heaviest band.  Latest snowfall reports show widespread 2-4" across northern Iowa with some heavier amounts over north-central Iowa.  Expect the snowfall to continue throughout the night, with total accumulations of 4-8" likely over northern Iowa with perhaps some isolated higher amounts.  Forecasts are still on track for 18"+ for northwest and north-central Iowa; and 10-15" across the remainder of northern Iowa.  Ice accumulations are also becoming a problem across the central portions of the state, with a tenth to over a quarter inch already reported.  Hazardous travel conditions have been ongoing for some time, with reports of multiple cars in ditches in several counties across the state.

We may see some breaks in the snow come tomorrow, but expect travel to continue to be hazardous through Friday and much of the day Saturday.  Snow totals look very impressive with this system, and with winds on the increase and the snow becoming lighter expect drifting to be a big concern as well.  An update in the morning will give the latest snowfall measurement here, and hopefully some graphical representation of the snowfall across the state as well.

Winter Storm: Dec. 23-25 Update #2

A mix of sleet, snow, and freezing rain has fallen today across the plains states.  Areas are now seeing some moderate to heavy snow across northern Iowa and adjacent areas, creating hazardous travel conditions already.  The latest Iowa road conditions indicate that there are roads in north-central Iowa that are completely covered, thus no travel is being advised.  These roads include I-35 from roughly highway 3 northward to the IA/MN border, along with several other major highways in that area.

I did some travel earlier this afternoon, and while most major highways had been graveled/salted to create just wet conditions many of the other county roads were ice/sleet covered.  With moderate snowfall the past hour or two, all of the roads are now becoming covered and thus becoming slick.  The map below shows the latest Iowa road conditions, otherwise check out the website for additional details:  Iowa Road Conditions



The latest NAM forecast run from this afternoon (18z) continues the trend of widespread 18+ inches of snowfall across the northern plains.  Perhaps just a slight eastern movement of the heaviest axis, with the low pressure system over eastern Kansas and continuing to gain strength this afternoon and should continue to do so through the day tomorrow.  The latest water vapor imagery does not indicate any dry punch with this low, thus expect widespread snow to continue unabated through the evening and overnight hours.  Later updates may hopefully have some of the snowfall reports from around the region.

Winter Storm: Dec. 23-25 Update #1

Roadways across northern Iowa and adjacent areas are slick in spots this morning as a layer of ice has fallen during the overnight hours, and may continue to lightly accumulate this morning across parts of the state.  Snow may begin to fall this afternoon across portions of northern Iowa, as well as other areas of eastern KS/NE/SD today.  This snowfall will likely continue through the day on Friday across northern Iowa and other areas of the northern plains, with snow totals reaching well above a foot over a significant part of the Dakotas, Minnesota, Iowa, Nebraska, and a few adjacent areas.  Other areas just south and east of this heaviest snow will see a mix of snow and sleet, and perhaps a few more hundredths to a tenth of ice accumulation as well.  Even further south and east with this system will see several inches of rain on top of the frozen ground, creating flooding hazards in some areas.

Luckily, I find myself in the best probabilities for over a foot of snow as rated by the HPC for both today and tomorrow.  I'll continue to post updates as I can as the snow begins to accumulate over the area.  The next update I'll give later this morning will have the latest model runs and their forecast snow accumulations.  Below is the latest Des Moines weather story, which gives a pretty good summary for the state of Iowa:


Tuesday, December 22, 2009

Winter Storm: Dec. 23-25

A significant winter storm is making its' move at one of the busiest travel times of the year for the central and northern plains.  Not only will significant snowfall accumulations of 10-20 inches be widespread and cause for concern, but ice accumulations of a tenth to over a third of an inch are also possible across parts of KS/NE/IA/MN/WI.  There is also a concern of flooding for areas that will be on the warm side of the system, with significant rainfalls falling on already frozen ground.  For the best details I would look to your local NWS office and local media stations, as this system is just too widespread to try to get all of the details posted.

For the best idea as to what type of precipitation and how much areas will receive, I'll go ahead and post a few model images from this afternoon.  Expect the heaviest snowfall amounts to fall across eastern NE/SD/ND, western Iowa, and southern Minnesota Wednesday night through Thursday; and over western Iowa, Minnesota and western Wisconsin on Thursday night through Friday.  Ice accumulations are also likely to be a concern from eastern KS/NE through Iowa and into portions of MN/WI/IL as well.

Below are the images from this afternoon's model runs of the NAM and GFS, both are snowfall accumulations from today through Friday at Noon.

NAM Accumulated Snowfall










GFS Accumulated Snowfall


Christmas Blizzard?!?!

Another major winter storm is expected to impact the central plains beginning today, and continuing through Friday and perhaps into the weekend for portions of the eastern Plains.  Snowfall accumulations well over a foot are possible across a large area of Kansas, Nebraska, Iowa, South Dakota and Minnesota.  Other areas may see significant accumulations of sleet and ice as well, mainly over parts of Nebraska and Iowa on Wednesday.  With snowfall beginning today over parts of KS/NE/SD, and continuing through Christmas day across areas of IA/MN/WI there is significant travel concerns.  It is likely that a large portion of major highways and interstates over these regions will become too hazardous to travel and may even become closed during the heaviest snowfall.  Winds are expected to increase as the low pressure system responsible for this winter weather strengthens on Friday, with winds nearing blizzard-like conditions over parts of NE/SD/MN/IA being possible on Christmas day.

I returned last night to northwest Iowa from moving a significant portion of my belongings down to Kansas City where I will begin my new job in early January.  Thus, don't have a good hold on how the models have been handling this system as their is some discrepancies in location of the heaviest snow.  Later updates today may hopefully define these areas better, and I will try and include a few quick model images or NWS weather stories for some graphical aids.

I will urge any of those likely do to traveling in this Wednesday through Friday time frame to carefully look at your schedule and your expected route, and either begin your travel today or wait until Saturday or Sunday at the earliest.  I expect their to be a large number of people who do not heed the warnings given on travel conditions and likely will make their Christmas even worse as they end up stuck on the roadways!