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!

Sunday, December 13, 2009

A Light Wintery Mix

A weak low pressure system will move across the plains during the day today and into the overnight, creating a mix of wintery precipitation across the state of Iowa and some decent snowfall amounts across parts of the northern plains.  The state of Iowa will roughly be split in thirds as far as precipitation amount and type goes with this system.  The northern third of the state will see snowfall during the day and overnight hours with accumulations of 1-2 inches possible.  The central third will see a mix of snow and freezing rain, with only light accumulations of each.  The southern third of the state may see a few freezing sprinkles or light showers during the overnight hours, with little accumulations if any expected.  The heaviest snowfall with this systems should fall across central Minnesota, including the metro areas of Minneapolis/St.Paul where 2-4 inches of snow may fall this evening and through the overnight.  For this reason there is a Winter Weather Advisory for many counties across central Minnesota due to this snowfall accumulation.

Beyond tonight weather system, more arctic air will move into the plains states leaving our temperatures in the single digits and teens with lows likely into the single digits above and below zero.  More details on our second arctic outbreak in the next update.

Thursday, December 10, 2009

Arctic Air & Snow Depth Wrap-Up

The blizzard has came to an end across the plains, with many areas are finishing the digging out process today under clear skies and calmer winds.  Storm totals for the state of Iowa were featured in the previous post and final update on the winter storm of Dec. 7 and 8.  As for a wider view of the plains, the attached image below shows the satellite estimated snow depth for the plains as of this morning.  Keep in mind this is an estimate taken by satellite with the aid of more localized observations, thus isolated higher amounts may be missed.  You can really see where the path of the storm dropped the heaviest amounts, and also see some of the lake effect snow that occurred over the UP of Michigan and extreme northern Wisconsin.

With the passing of this system, we are now left under a very cold arctic high pressure system leaving temperatures well below average across much of the plains.  Looking at the state of Iowa for the next few days we'll see a steady increase in the temperatures, however, nothing that will begin to melt any of the snow that we've received thus far this season.  Overnight lows tonight with range from the mid-single digits below zero in the northwest to the mid-single digits above zero in the southeast.  Friday's highs will range from the teens to lower 20s from north to south, with overnight lows in the single digits in the west and south and the single digits below zero in the northeast.  Weekend highs in the 10-20 degree range from northwest to southeast, with overnight lows in the teens to lower 20s.  There is a slight chance of a few snow showers/flurries and even a mix of sleet for Saturday night through Sunday night across the state.  No accumulations are expected...

Wednesday, December 9, 2009

Winter Storm: Dec. 7/8 Update #6

Snowfall has came to an end over much of the central plains, with some snow still falling over the eastern plains and the great lakes regions.  While the snowfall has ended, the winds are continuing to be gusty and blow the light snow creating blizzard-like conditions across a large portion of the plains.  This blowing snow has created hazardous travel conditions as visibilities are reduced to under a mile and snow drifts have made some routes impassable.  The latest update from the Iowa DOT lists at least 5 major highways or interstates that are closed due to being impassable thanks to snow drifts.  Those include I-35 between Des Moines and Ames; portions of US 30 in central Iowa; I-80 between Des Moines and Iowa City; and US 6 near Omaha.  Many other county highways and especially rural roads are also impassable and will likely remain so until tomorrow when the winds begin to subside.

The latest information from the coop observers across the state of Iowa show snowfall varying from 6-8 inches in the northwest, and 4-6 inches in the southeast, to upwards of 16 inches across other parts of southwest, central, and northeast Iowa.  Their latest image is below:

Tuesday, December 8, 2009

Winter Storm: Dec. 7/8 Update #5

A great tool that the Iowa Environmental Mesonet has came up with and is now featuring on their front page.  This is a graphical representation of all the snowfall reports that have came in within the past 4 hours across the state of Iowa, and is updated approximately every 5 minutes.  Be sure to check it out:

Winter Storm: Dec. 7/8 Update #4

The winter storm is in full swing, with blizzard-like conditions beginning to occur across portions of the plains.  Many road departments are now urging to not travel as winds have increased and the snow has begun to drift across roadways, which in nighttime conditions can be very hazardous.  Total snow accumulations vary across the state of Iowa, with 3-5 inches over northwest Iowa and upwards of 6-8 inches over central and southern Iowa.  Expect a few more inches to accumulate yet tonight as the low pressure system finally pushes east of the state.  This movement east, along with its' strengthening, will bring increased winds for the plains with gusts of 40-50 mph likely.  Expect many closings for tomorrow's events and schools with roads becoming impassable during the overnight tonight.  Here is a quick updated graphical forecast from the Sioux Falls National Weather Service:

Winter Storm: Dec. 7/8 Update #3

The morning GFS (12z) model forecast continues the trend to indicate significant snowfall accumulation across the plains states, similar to this mornings NAM model forecast.  Total snowfall accumulations of over a foot are likely across parts of Iowa, Minnesota, Wisconsin, and perhaps even Illinois and other adjacent areas.  Moderate snowfalls are occurring across the area, and accumulations nearing a half foot are already occurring over areas of southern Iowa and nearby areas.  Additional updates are likely later this afternoon as more details on accumulations are given, and if any road conditions warrant a quick update.

Morning (12z) GFS Snow Accumulation Forecast

Winter Storm: Dec. 7/8 Update #2

The National Weather Service in Des Moines, IA has now upgraded much of their region to a Blizzard Warning based upon the latest snowfall forecasts and expected wind speeds.  Their opening line in their issuance is "...AN EPIC AND EXTREMELY DANGEROUS WINTER STORM TODAY THROUGH WEDNESDAY...".  Snow accumulations of 10-14 inches appear likely across much of central Iowa, with snow drifts of 8-15 FEET possible by Wednesday given winds of 25-35 mph and gusts upwards of 50 mph.

I am now located on the western edge of the blizzard warning, and am expecting 8-12" of snowfall by sunrise tomorrow.  However, given such wind speeds I think you'll find quite a variance in snowfall amounts dependent upon where you measure as drifts will definitely be a concern.  Be sure to keep an eye on latest closings, and the latest road conditions which are sure to become 'travel not advised' by this evening and during the overnight.

Winter Storm: Dec. 7/8 Update #1

Snow has begun to fall across much of the plains states, with several inches of accumulation already being reported in some areas where the snow has been falling much of the morning.  Schools and businesses have already begun closing or are already closed for many of these areas, with all nightly activities being canceled and even a few events for Wednesday being postponed as well. 

Snowfall reports have only been light to moderate thus far, but should pick up later this afternoon.  Even with only light to moderate snowfall, several hours of accumulation will be able to make hazardous travel conditions given an increase in wind speeds later this evening with the strengthening low pressure system.  This mornings update will just include a quick look at model guidance once again, this mornings' 40km NAM indicates a slight northward turn to the track of the low pressure system and an actual increase in proposed snowfall accumulations!  Widespread accumulations of at least a foot of snow is forecasted across a significant portion of the plains, with isolated higher amounts.  The forecast image is below, and we'll have to watch how the snowfall and low pressure system evolves as to whether this latest forecast will be accurate.

12z (morning) 40km NAM Snowfall Accumulations

Monday, December 7, 2009

Winter Storm: Dec. 7/8

A significant winter storm is expected to impact much of the plains states beginning tonight and continuing through Tuesday and into Wednesday.  Winter Storm Warnings have been issued as far west as the NE/KS and Colorado borders to the east and northeast to the upper peninsula of Michigan.  Winter Weather Advisories have been posted for many of the areas adjacent to the warnings, with snow accumulations still up to 6 inches in those areas.  As the low pressure system strengthens during the day on Tuesday and into Tuesday night, expect a significant increase in the winds for portions of IA/MN/WI/IL.  For this reason, a blizzard watch and even blizzard warnings have already been posted where conditions are likely to become favorable for significant snowfall accumulations of 1-2" per hour and wind speeds sustained at greater than 35 mph.

Forecast models continue to be consistent in indicating the heaviest snowfall axis from north-central Kansas into Nebraska, Iowa and Minnesota.  Adjacent areas and areas further northeast will also see significant amounts, however not on the same terms of 10-12" that are possible over those areas of KS/NE/IA/MN.  This storm will be a very strong first winter storm for many, meaning that travel conditions will be very treacherous, and likely will result in travel not being advised for a significant portion of the plains.  It will be important to head these warnings, as conditions will likely deteriorate quickly with strong winds, and wind chills will be well below zero for those that do become stranded.  There will be plenty of coverage by local news stations and even national news stations as this event will cover so much of the plains states.

The latest snowfall forecasts by tonight's (00z) model runs are posted below:

00z 40km NAM

00z 5km WRF

Additional updates are likely tomorrow as the storm begins to affect the plains states, however, updates may be scarce as my location is within the warning area.

Sunday, December 6, 2009

A Return to Snow... Lots of Snow...

My wife and I arrived back onto U.S. soil on Saturday morning, at the rainy and unseasonably cold port of Tampa, Florida.  From their we left the airport in the early afternoon and arrived into the cold air of Minneapolis, MN by evening and then continued our drive back into northwest Iowa by the early nighttime hours.  Some light snow was seen over central Minnesota, but a few inches were left on the ground in southern Minnesota and northern Iowa.  This couple of inches are likely to increase quite a bit by midweek as a strong storm system has already forced Winter Storm Watches and Blizzard Watches to be issued.

A low pressure system will come off of the Rockies during the day on Tuesday, and arrive into the western plains states by Tuesday night as it continues to strengthen.  By Wednesday morning the low pressure system should be nearing the Ohio Valley, and has continued to strengthen overnight leaving a very strong pressure gradient across the northern Plains.  This pressure gradient will be responsible for widespread winds of 25-35 mph across the plains, with higher gusts upwards of 50 mph possible near the Mississippi Valley regions of MN/WI/IA/IL.  These winds will be a secondary factor with this system, as snowfall amounts will be significant across a large portion of the plains including portions of KS/NE/IA/MO/MN/WI/IL and perhaps even more areas beyond the Wednesday time frame.

This morning model runs continued with fairly consistent forecast of snowfall amounts for the plains states, and as this system does still have some time to finalize its' details I'll keep this post shorter with just a few map updates regarding snowfall amounts through Wednesday night.  Additional updates tomorrow and Tuesday as the system reaches the plains will contain more specifics regarding timing and snowfall amounts.

12z (morning) NAM Snowfall Accumulations

12z (morning) GFS Snowfall Accumulations