Wednesday, December 31, 2008

Iowa 2008: A Weather Review

While I was present throughout much of this year's weather that occurred throughout the state of Iowa, it was helpful to read through some of these great products that the Des Moines National Weather Service has issued over the past couple of days. It will remind you of the bitter cold that was endured in January and February, which also coincided with one of the snowiest February's on record for the state. These events led into a very active spring, it started dry for March and quickly turned to a very wet April. A break in the rain for mid-May would only help the farmers get their crop in the fields, as the latter half of May led to the destructive and national news headlines of the Parkersburg, IA tornado. The state wouldn't stay out of the national spotlight for too long, as the floods across much of Iowa would once again enter during the month of June. Tornadoes would once again lead to national news headlines for the state of Iowa, as on June 11th several boy scouts were killed near Little Sioux, IA. The state ended the summer with heavy rains and more flooding in July, and then a record-setting dry spell for the month of August. The warmth of summer and fall would be the only headlines for the next couple of months, with a very late fall freeze. This warmth continued into the early part of November with temperatures continuing in the 70s and even an 80 degree reading. We finally got back to the cold air that we started out the year with in the latter half of November and this has continued for the most part through the end of the year. December has also brought headlines with the continued round of snow storms, with blizzard and near-blizzard conditions and snowfall amounts greater than 20 inches to lead this month as the 4th snowiest December in Iowa history.

For a complete review of 2008 view the Des Moines NWS document here: DMX NWS Year in Review

Another read for those interested in this years' tornadoes across the state will be the table-listing of all tornadoes. It includes the city, county, specific location and time of each tornado; it will also show the maximum length and width of each tornado along with any injuries and deaths that unfortunately were to occur with the tornado. To view this document, head to the link: 2008 Iowa Tornadoes

Thanks for making this a successful year of the blog, with several thousands of readers and with the comments and views that I'm sure to keep going. Hope you had a great 2008, and here's to looking forward to a even better 2009!

Sunday, December 28, 2008

Melting Ice

The past couple of days left parts of the state under a few tenths of an inch of ice, while other parts saw plenty of melting snow due to the rainfall that was occurring. This rapid melting and additional rainfall has prompted a few flood warnings over the southeast quarter of the state. Additional melting is likely to occur over the next few days as well as temperatures continue to be well above normal through Tuesday before our next storm system begins to work into the state. For the quick recap on the past few days weather, a map below shows the ice accumulations that have occurred on Dec. 26/27:

For the next few days it looks like we'll stay dry and warm with southerly winds and sunny skies. Through Tuesday you can expect highs to range from the lower 30s across northern Iowa to the lower 40s across the southern third of the state. The lows to go along with these warmer temperatures during the day will also be well above normal, with the teens to mid 20s expected Sunday night. Monday night will be even warmer with lows near 20 across the north and near 30 on the southern border of the state. Beyond these warmer temperatures we'll see another storm system move in and give us a chance of snow on Tuesday night for northern Iowa; expanding to cover more of the state for Wednesday and later. It looks like we'll end the year without another major storm system, time to prepare for 2009!

Saturday, December 27, 2008

Mixed Precipitation...

The Holidays have been busy, thus I'm sure with everyone traveling the road conditions have been important to many. There hasn't been too many problems thus far, with mainly some snow and blowing snow to contend with on the roads. Yesterday was quite warm with a warm front moving north over the state allowing temperatures to reach well into the 30s and 40s even with snow cover. These warmer temperatures are now on their way back down with a cold front passing through the state. This cold front and associated low(s) are responsible for areas of sleet/snow and freezing rain over parts of the state this morning.

A Winter Weather Advisory has been issued for many areas along and east of I-35 for this mixed bag of precipitation that should continue through this afternoon and into the overnight hours. Areas along I-35 should see light accumulations of both sleet and freezing rain during the day, with snow beginning in the evening and into the early overnight with accumulations of 1-3 inches of snow. Further east the situation becomes a bit messier with rain expected through much of the day, with isolated thunderstorms even included in the forecast. Rainfall totals of a quarter to half-inch are possible, with an eventual change to sleet/snow being possible during the evening and into the overnight. Travel conditions are likely to be hazardous over the eastern half of the state beginning this evening and continuing through the overnight hours with the mixed precipitation.

Tuesday, December 23, 2008

Even More Snow!!

While the first brush of snowfall has made its' way over much of the state during the overnight hours it will keep a few flurries or snow showers around in the central/eastern parts of the state early today. A dusting to a few inches may be expected from central to eastern Iowa, the eastern third of the state has been put under a Winter Weather Advisory for their chances of seeing an additional 1-3 inches of snowfall today, leaving their storm totals from 2-5 inches. This additional snowfall has created some troublesome areas of travel as roadways are being reported as mostly to completely covered this morning.

Beyond today's snowfall, the next event to come across the state is expected on Wednesday as a low pressure system begins to form over the Midwest and track northeast. This low will move east of the state of Iowa, but it will likely put areas of eastern Iowa in a favorable location for receiving potentially significant snowfall amounts. It is for this reason that areas of eastern Iowa (approximately the eastern third) have been put under a Winter Storm Watch for Wednesday. While much of the state may see a few flurries or light snow, areas east of a Nebraska City, NE to Des Moines to Waterloo to LaCrosse, WI line will likely see greater than 3 inches of additional snow. Some areas, mainly east-central Iowa, may have the potential for 6 inches or more of snow through Wednesday. This snowfall combined with an increase in winds will create blowing and drifting snow, and of course hazardous driving conditions on Christmas Eve. Later updates will refine the snowfall totals and locations for this Christmas Eve snowfall...

The latter half of the week will be full of interesting weather to go along with those interesting family times. A potentially strong storm system to the west of the state will lift warm air into and through Iowa during the day on Thursday and Friday. This warm air will allow even surface temperatures in the upper 20s and lower to mid 30s despite the snowfall. While this will hopefully create a crust on the current snowfall to hamper any additional blowing snow, it may create problems of its' own with any precipitation that falls. Forecasts have a wintery mix, to even rain in the forecast across the state on Thursday afternoon through Saturday. As you may be thinking, ground temperatures will certainly not get above freezing with the considerable snow cover, thus leaving any liquid precip as freezing upon contact with surfaces. Be prepared to leave early or travel in some hazardous conditions if this comes to be for the latter half of the week. Luckily at this time it does not appear to be significant or widespread, but something to keep an eye on for holiday travel.

I had a question on the previous blog entry about more of a long range forecast, and wish to at least give recognition to it here. With all that has been going on in the short term, I haven't taken a long look at the January forecasts, etc. Weather models in the long range will change quite often, thus there is no good way to indicate anything more than trends. Current Climate Prediction Center forecasts do have Iowa in a probability area of seeing above normal temperatures in January. Above normal temperatures in January won't necessarily be above freezing, rather temperatures in the teens and 20s on average instead of some single digits and lower teens.

Monday, December 22, 2008

A little more snow...

Another storm system will clip the state tonight and continue to produce some light snowfall through Tuesday night. While snowfall amounts are not expected to be too high, just below advisory criteria, the snow combined with already full ditches may produce some troubled driving conditions over parts of northern Iowa. Temperatures should become a little warmer with the snowfall, and continue to be warmer than the past couple of days through Wednesday.

Total snowfall amounts through the next 36 hours should range between only a trace for areas southwest of a Sioux City to Ottumwa line; with 2-4 inches possible for areas northeast of a Spirit Lake to Waterloo to near Davenport line. The area in between should see 1-2 inches of snowfall... Winds are expected to be breezing, at 10-20 mph which may give way to some blowing snow, especially in those areas where the ditches, etc. are already full.

In a previous post I included an image of snowfall depth across the state, and with the last snowfall there is now an updated snow-depth map that is attached below:

Saturday, December 20, 2008

Winter Storm (Dec. 20) Update #2

Light to moderate snowfall combined with strong northwesterly winds have allowed travel conditions across the state to deteriorate throughout the day. Most of north-central and northeast Iowa have been advised to not travel due to the road conditions. These strong winds will continue to create hazardous travel conditions across the northern half of the state through early Sunday.

Beyond the blowing snow and windy conditions, these will combine with temperatures near or below freezing throughout the next 36 hours to create dangerous wind chill value. Much of the state will see wind chills below -20 during the day tomorrow, and even below -30 during the evening and overnight hours tomorrow and Monday night as well. Be sure to keep bundled with the very cold and windy conditions through Monday night...

The image below is the latest snow depth across the state of Iowa:

Winter Storm (Dec. 20) Update #1

The Blizzard Warning has been expanded to include areas along and north of Highway 20, and areas along and west of I-35. A Winter Storm Warning has been issued for northeast Iowa where snowfall amounts and winds will still create hazardous conditions, but won't quite reach blizzard criteria. Snowfall has continued to fall this morning across the state, with 2-4 inches expected across the northern third of the state. The central third of the state should see 1-3 inches, and the remainder of the state may see an inch or so. Although travel conditions aren't too bad at the moment with only snowfall, as a cold front sweeps over the state the winds will increase significantly this afternoon and continue into Sunday. These northwest winds will likely be sustained at 20-35 mph, with gusts up to 40 mph. The combination of fresh snowfall and these winds will create blizzard or near-blizzard conditions across the northern third of the state of Iowa as well as areas of Minnesota and South Dakota. These blizzard conditions are likely to continue into Sunday morning and early afternoon, making traveling very hazardous or not impossible over some areas.

I did have one comment on the previous post asking about travel conditions, making the trip from near Rochester, MN to Des Moines, IA. While I can't say if they will be closing down I-90 or I-35; it will be a very hazardous trip to make anytime during the day today/tomorrow. It may have been best to make the trip early this morning, or else you can wait until later on Sunday and hopefully the winds may subside a little early. Updates may be posted as blizzard conditions begin and continue through today and tomorrow...

Friday, December 19, 2008

Winter Storm (Dec. 20)

The third winter storm of the week is headed towards the state and will begin early tomorrow and continue into Sunday. Areas along and northern of highway 30 are most likely to be effected by this storm, and this is where there are currently Winter Storm Watches issued for north-central and northeast Iowa. Parts of northwest Iowa have been put under a Winter Weather Advisory for tomorrow morning, and then a Blizzard Warnings for the afternoon into Sunday morning. The portions of the state that are currently not under an advisory/warning are likely to be put under one later this evening/tonight. A band of 1-3 inches of snow is possible between highway 30 and highway 20; the northern third of the state is likely to see 2-4 inches with isolated higher amounts.

The bigger story of this winter storm will not be the snowfall amounts like the last one; rather the high winds that are to pick up after the snow falls. Once a cold front slides through the state during the afternoon hours tomorrow, expect winds to increase out of the northwest at 15-25 mph sustained with gusts near 35 mph. These winds will create heavy blowing and drifting snow, and dangerous wind chill values throughout northern Iowa.

The next storm update is possible late tonight once any updated advisories/warnings have been issued...

Winter Storm (Dec. 18) Recap

A dangerous winter storm created havoc for much of the state of Iowa, and surrounding locations. Snowfall was prominent throughout the northern half of the state where 5 inches or greater was seen. The heaviest snowfall was in parts of northwest and northeast Iowa where reports of greater than 8 inches were received. Luckily this snow was very light and fluffy, and with little in the way of wind it was not a problem to get off of the roads. The other concern was the ice and sleet that occurred over much of central and southern Iowa, the heaviest amounts seemed to be in localized locations across southern Iowa. Images of the snow accumulations and ice accumulations via the NWS Des Moines are posted below.

Ice Accumulations

Snow Accumulations

Thursday, December 18, 2008

Winter Storm (Dec. 18) Update #4

The winter storm has arrived! Widespread reports across the southern half of the state of sleet and freezing rain, with some accumulation and icing already occurring. Some areas of southeast Nebraska have already reported a half inch of sleet, and other reports of an eighth of an inch of ice accumulation. These heavier reports have been co-located with reports of thunder and lightning that were quite frequent. These heavier amounts have just moved into southwest Iowa as well, with the latest report coming in from Council Bluffs, IA with nearly a half inch of ice accumulation; power lines are already sagging there.

You can view the latest radar from the Iowa Chaser homepage, as you see the precip overspread the entire state!

Watch your local news and check your local National Weather Service homepages for the latest updates and accumulation statements. Undoubtedly a very dangerous winter storm, be sure to also watch the road conditions across Iowa via where you can also watch the conditions rapidly deteriorate.

Winter Storm (Dec. 18) Update #3

Our potent winter storm is taking its' time to move through the plains, the low pressure system is currently over eastern Colorado and is expected to make its' way off of the Rockies this evening. Rapid pressure falls have been occurring over western Kansas, indicating that the low should move to the east/southeast over the next few hours. Once off the Rockies this low will rapidly move eastward over Kansas and through northern Missouri overnight, leading to heavy precipitation over parts of Iowa. The latest weather models have moved the the system just slightly north, moving the axis of heaviest snow/sleet with it. Once again both of the main weather models (NAM & GFS) are in remarkably good agreement with the movement of this system as well as precip amounts.

The heaviest freezing rain should still be south of I-80, and especially over south-central and southeast Iowa where nearly a half-inch is likely. Other areas south of I-80 should still see a quarter of an inch or more of ice. Sleet is also likely to occur over much of central Iowa between the I-80 and highway 30 corridors; total amounts between a half-inch and an inch are likely. Heavy snow throughout the night seems likely over the northern half of the state, with embedded thundersnow also possible. An axis from near Sioux City through Algona, and eastward toward LaCrosse, WI and points north/south within a few counties are likely to have the heaviest amounts of 6-10 inches. Other areas are still likely to see 4-8 inches...

More brief updates late tonight or early tomorrow are likely with reports of accumulations...

Winter Storm (Dec. 18) Update #2

The National Weather Service offices that cover the state of Iowa were busy last night, issuing several different winter weather advisories/warnings. A quick overview of these warnings: A Winter Weather Advisory is in effect for a few of the far western Iowa counties, a Winter Storm Warning is in effect for areas north of I-80 throughout much of central and eastern Iowa; and finally a Ice Storm Warning is in effect for much of the state that is south of I-80. These advisories and warnings go into effect this afternoon and will continue into Friday morning while precipitation falls throughout this period.

The latest models are in very good agreement for this winter storm with both positioning and QPF amounts, along with precipitation type. The heaviest band of snowfall is expected to fall from a line just south of Sioux City, northeastward to near Webster City, and then just south of LaCrosse, WI. Areas along and north/south of this line are likely to see greater than 6 inches of snow, with isolated amounts near one foot. These heavier snow amounts may likely occur within areas of embedded thunder, in fact, several areas in the southern half of the state may see embedded thundershowers with this system. These thunderstorms will have the potential to put down several inches of snow, or significant amounts of sleet or freezing rain within a short period of time.

This system has the potential to be extremely hazardous, producing over a half inch of freezing rain for the southern third of the state; significant sleet and freezing rain mixtures; and very heavy snowfall amounts. Des Moines NWS once again has a very good graphic depiction of the events likely to occur this afternoon and through the overnight hours. Thanks to a reader that posted a comment in the previous update, indicating that freezing drizzle is already beginning over parts of the state.

Wednesday, December 17, 2008

Winter Storm (Dec. 18) Update #1

Winter Storm Watches still are to remain in effect until later tonight where they will likely be changed over to some type of winter storm warning, whether it be for snow, or sleet/freezing rain. This mornings computer models came into a little better agreement on the placement of significant freezing rain and sleet. However, the overall location of the heaviest precipitation was still somewhat varied in mainly the east/west location. For a quick overview, models are still expecting a low pressure system to develop off of the lee of the Rockies on Thursday and quickly move into the central plains by Thursday night. The low track is expected to be through northern Missouri and into central Illinois, thus putting Iowa into the favorable area for continued precipitation. Rapid moisture return ahead of the system (up to 3 times the climatological average), along with warmer temperatures will allow for significant QPF amounts. This system is fast-moving, thus precipitation may begin Thursday afternoon over the state and may exit the state completely by Noon on Friday. For a graphical depiction of what is expected, please view the graphic below:

Yes, the image is hard to read... It has to be to put in all of the different precipitation types and amounts that are expected with this storm. Essentially the blue circle represents areas where more than 4 inches of snow is possible; the yellow represents up to an inch or more of sleet; and the red indicates areas where more than a tenth of an inch of freezing rain is possible. Enjoy this weather!

Winter Storm (Dec. 18)

The entire state of Iowa is now under a Winter Storm Watch for Thursday and Thursday night, with significant accumulations of snow, ice, and sleet possible dependent on your location in the state. A storm system is expected to develop during the afternoon hours on Thursday, with a low pressure center likely to track through northern Missouri and into central Illinois. This will put the state of Iowa in a favorable location for continued precipitation during the afternoon hours on Thursday and continuing into early Friday. With moisture expected to be sufficient, over a half-inch of precipitation is likely throughout the state with some higher amounts. This precipitation may fall as freezing rain, sleet, and snow creating very hazardous driving conditions.

Current forecasts would indicate that the southern half of the state may see greater than a tenth of an inch of freezing rain, followed by sleet and a few inches of snow. The northern half of the state may see some freezing rain and sleet, but a majority of precipitation should fall as snow; leading to more than 6 inches of snowfall for most of the area. These winter storms are especially hard to forecast for, so be prepared for all modes of winter weather including significant icing, sleet, and snowfall...

An afternoon update will likely be posted with any forecast revisions...

Tuesday, December 16, 2008

Winter Storm (Dec. 16) Update #3

The snow has subsided over most of the state, with only a few flurries or light snow showers over eastern Iowa. Total snowfall amounts were generally 3-4 inches over the state, with a few locations seeing a little more or little less. The highest amount through the Des Moines NWS office was near 5 inches in Jefferson. Here in Ames we saw just about 4 inches of the fluffy white stuff fall throughout the day...

Some hazardous travel conditions occurred when the roadways were completely covered, with a few accidents being reported throughout the state. Just a short update here, I've attached the general snowfall image from the Des Moines NWS to give you an idea of how the snowfall accumulated over the state.

Look for an update tomorrow morning that will give you the forecast for the next winter storm that will move across the state on Thursday. A Winter Storm Watch has already been issued for much of eastern and southern Iowa where significant ice/sleet/snow is possible. For a quick look at what is possible, the latest weather story from Des Moines is a sight to see:

Winter Storm (Dec. 16) Update #2

Light to moderate snow has continued across the state for much of the morning hours, accumulating snow at a slow but steady pace. No official snow amounts besides the NWS in Johnston (1/2 inch) have came out, although I can say Ames looks to have nearly 2 inches of snow on the ground at this time. The radar has been updating on the Iowa Chaser homepage for most of the morning, and as you can currently see the heaviest of the snow looks to be over the western third of the state. This heavier band of snow should move through central Iowa early this afternoon and over eastern Iowa during the late afternoon hours. Total snowfall accumulations over the southern two-thirds of the state should be in the 3-5 inch range, while extreme northern Iowa should still have at least 2 inches of fresh snow on the ground. Expect the snowfall to end over western Iowa this afternoon, over central Iowa this evening, and over eastern Iowa during the early overnight hours.

Travel conditions are not too bad, they are partly to mostly covered with snow dependent upon the last time the plows have went over the area. Do expect some slower travel beings the snow can be slick at times, but overall this system is just a nice snow-maker.

Monday, December 15, 2008

Winter Storm (Dec. 16) Update #1

A winter weather advisory has been issued for all but the extreme portions of northwest Iowa beginning tomorrow morning and continuing into Tuesday night. Areas under this advisory may see 2-6 inches of snowfall with some isolated higher amounts possible. The heaviest snowfall is still likely to be over the southern two-thirds of the state, with the northern third likely to only see 2-4 inches. This snowfall will be moderate to heavy at times as it moves through the state tomorrow, so expect some hazardous travel conditions.

Winds are expected to be lighter, thus blowing and drifting snow is not a large concern. Temperatures are still likely to remain well below freezing, leading to the significant snow amounts across the state. More updates on the winter storm will be posted tomorrow afternoon as the snow falls.

Sunday, December 14, 2008

Winter Storm (Dec. 16)

Our next winter storm will make its' way into the state by tomorrow morning, and with the frigid air in place it will undoubtedly be an all snow event for the state. As our storm system that affected us yesterday continues to move east, an area of high pressure will setup over the state today and tonight keeping the temperatures well below normal. We'll then see a wave of energy come through Tuesday afternoon, this is what will be responsible for the snowfall across the state of Iowa and surroundings. Although the system as a whole does not look potent, the combination of the shortwave and temperatures will allow for moderate to heavy snowfall to occur across the state.

The computer models have been consistent in bringing this snowfall over the state throughout the day on Tuesday, thus there are no real concerns of this event not happening over Iowa. The band of heaviest snowfall has been consistently painted by a consensus of the models over the southern third of the state. Northern Iowa won't miss out though, still seeing several inches of snow throughout the state. The snowfall will be heaviest in the morning hours over western Iowa, the afternoon hours in central Iowa, and then during the evening hours over eastern Iowa. Although winds are not expected to be as high, thus limiting the blowing snow; travel conditions are still likely to be hazardous due to the snow and reduced visibilities.

With QPF expected in the .2 to .5 range across the state, and with snow:water ratios ranging from 12:1 to 20:1 it will not take much to see snowfall rates greater than an inch per hour. This has led me to this crude map of potential snowfall amounts across the state for tomorrow. Enjoy the snow! An update will likely be issued tonight upon the NWS issuing advisories/warnings for this storm system.

Winter Weather (Dec. 14-15)

Plenty of updates today with this strong system moving through the plains states, and directly over the state of Iowa. As the low pressure system moves through Wisconsin tonight, expect continued northwesterly winds at 20-30 mph with higher gusts. With frigid temperatures and these high winds, the concern over the entire state will be wind chill values in the -10 to -30 degree range. These values have prompted nearly the entire state to be put under a Wind Chill Advisory. Some bands of snow are possible over areas of northwest Iowa, where less than an inch is expected. However, with the strong winds a Winter Weather Advisory has been issued for some areas in northwest Iowa due to the strong blowing snow. In the southeast, a heavier band of snow is likely to take place tonight and allow anywhere from 1-2 inches of snow and sleet to fall. This combined with the strong winds will also allow for blowing and drifting snow, leading to the issuance of Winter Weather Advisories and Winter Storm Warnings.

So for tonight, expect continued strong winds and bitterly temperatures, along with some snow in the northwest and southeast. Hazardous travel conditions are likely throughout the state, and bitterly cold temperatures and wind chills are definite.

Expect the temperatures to slowly rise tomorrow, and the winds to slowly decrease as well to allow the wind chill values to make it above -10 and thus void any wind chill advisories. We'll only see a one day break from the snow though, as Tuesday looks to have another storm system dropping upwards of 6" of snow somewhere in Iowa!

Amazing Cold Front

The cold front that has been plunging southward today continues to do so through nearly the entire plains states. This front not only has such deep cold air behind it that is creating below zero readings from Montana through the Dakotas and Minnesota, but is so strong that is has over 30 degree drops in temperature along it without the aid of any precipitation! Temperatures are in the teens from northern Minnesota into the panhandle of Oklahoma, with temperatures in the 50s as far north as Illinois ahead of the cold front. The low pressure system responsible for such a strong front can clearly be seen through the image below, just temperature gradients alone should give it away let along the strong winds that wrap up nicely around it.

The image below should tell it all, with the temperatures shown in the red text, and temperatures also color-contoured for emphasis. Winds shown through the wind barbs as well to indicate the cold air rushing in behind as the front passes.

Welcome Back Winter...

Winter tried to take a break from the state, with temperatures rising well above freezing in some areas and the sun shining brightly. It didn't last too long though as a strong cold front and low pressure system have moved into the state this morning and allowed temperatures to free-fall with winds increasing 20-35 mph. The combination of falling temperatures and continued high winds will allow wind chill values in the -20s and -30s tonight across parts of northern Iowa. Some snowfall is also expected across the state this afternoon and overnight as the cold front and low pressure system move through. The heaviest amounts are likely over southeast Iowa where 1-2 inches of snow is possible during the overnight hours. Beyond today, expect the cold conditions to continue through Wednesday this week...

Lows tonight ranging from -10 to 10 degrees from the northwest corner to the southeast corner. As mentioned previously, with strong northwest winds the wind chill values will be well below zero across the entire state. Highs on Monday will range from the single digits to the teens across the state, with lows falling into the teens below zero and single digits at best. A slight warm-up on Tuesday with highs near 10 to near 20 from northwest to southeast. Tuesday night lows will range from the single digits above and below zero to a few temperatures just above 10 degrees in the southeast. Teens to lower 20s expected on Wednesday, with lows overnight finally ranging in the single digits above zero for the entire state.

I'll leave today's post with an image that I took today just north of Pocahontas, Iowa where a northbound semi lost control due to high winds and somewhat slick conditions and managed itself into the southbound ditch.

Tuesday, December 9, 2008

Dec. 8-9 Ice/Snow Accumulations

Although blowing snow continues to create some problems, the snow is exiting the state and we will just be left with the wind and cold to deal with. Snow accumulations were not as high as expected for most of the state yesterday into today, this was mainly due to some slightly warmer air being present just above the surface. This warmer air allowed the snow that was falling to melt before reaching the surface, and then freeze upon contact creating the freezing rain. Freezing rain accumulations ranged from a tenth across much of the state to over three-tenths in parts of northeast Iowa. Each tenth of an inch of freezing rain could have easily contributed to more than an inch of snow, adding to the accumulations that those areas received later on during the early morning hours after the freezing rain had turned into snow.

The snow accumulations weren't light everywhere, with much of northeast Iowa receiving 5-9 inches of snowfall on top of the couple tenths of ice accrual. Areas that only saw a couple inches of snow still didn't make it without trouble due to strong winds blowing the snow around on top of their minor ice accumulations. Maps of the snow/ice accumulations are being added below when available:

Beyond today's cold and windy weather we can look for only partly cloudy skies the rest of the week with temperatures in the 20s to mid 30s from northeast to southwest across the state. Lows overnight will be in the single digits and teens tonight, to the teens and low 20s for the rest of the week. We look to only have a small chance at some flurries a few nights, otherwise looking towards early next week for our next round of winter precipitation.

Monday, December 8, 2008

Winter Storm (Dec. 8-9) Update #2

Precipitation has been falling off and on throughout the entire state this afternoon and into this evening. While the northern third of the state has seen this precip turn over to snow, other areas of central Iowa are seeing freezing rain, while the southern third is hanging onto rain. This type of precipitation should continue through the early nighttime hours, with the northern third of the state continuing to see snowfall and the other portions seeing a mix of freezing rain and rain. By the late nighttime hours, the snow should begin to fall over the central third of the state while the southeast quarter of the state stays rainfall. Waking up on Tuesday will likely be quite the mess with ice accumulations in some areas, heavy snow in others, an majority of the state in a simple mess of winter weather.

The heaviest snowfall accumulations are expected to occur over north-central and northeast Iowa where winter storm warnings have been issued with 4-8 inches of snowfall possible. Other areas under a winter weather advisory may see snowfall accumulations of 2-6 inches, or some ice accumulations along with moderate snow. Only the southeast quarter of the state will be able to remain under a couple inches of snow, with little in the way of ice accumulation as well. Other areas of extreme weather Iowa will be far enough away from the low to only see a couple inches of snowfall.

Keep up with the latest road conditions and the latest radar from the Iowa Chaser Homepage.

Sunday, December 7, 2008

Winter Storm (Dec. 8-9) Update #1

Well I know the previous post mentioned that a better idea of snow accumulations would be presented in this update tonight, but honestly there can't be that much accuracy stated at even this point. Tonight's model runs at first glance have continued their trend of a north and west movement of the heaviest snow, likely due to the more progressive nature of the system. However, this does not seem to hamper any of the current NWS statements on the winter storm watches currently in effect and it certainly doesn't mean that the new solution will verify either. I am however not going to be able to provide a solid map for your visual reference on how much snow areas are likely to receive.

Precipitation is likely to begin by the evening hours tomorrow, with a few scattered showers during the afternoon hours previous. With the strength of warm-air that is likely to push into the state, it does appear that rain may be the beginning form of precip for much of the southern half if not greater portion of the state. Current surface analysis indicates this warm front is already in the process of taking shape over the southern third of the state. This will provide the good possibility of freezing rain for much of the state on Monday afternoon and into the evening hours. As we head into the heavier precip on Monday night, expect western and northern Iowa to be mainly snow, central Iowa to be mainly snow with the transition a little later in the night, and expect southeast Iowa to be mainly rain; leaving parts of south-central, central, and east-central Iowa with the possibility of continuing freezing rain. All in all, with the amount of precipitation expected with this storm system, a good winter storm is nearly a guarentee, it is just the location that is tricky at the moment.

Latest forecast discussions tend to agree with this detail, with the heaviest band of snowfall possibly falling anywhere between the I-90 corridor in southern Minnesota and northern Iowa, to south-central to east-central Iowa. As mentioned by Des Moines NWS, central Iowa does appear to be in the most likely area for this heaviest band of snowfall to setup during the overnight hours on Monday. Widespread 4-6 inches of snow is likely, with isolated amounts nearing 8 inches. Areas just to the north/south of this heavier band should still see 2-4 inches, with only extreme southeast Iowa perhaps making it out with only an inch or two as they receive more rainfall than snow...

As I type, I figured I might as well make up a map... So it is posted below, notice the area encircled in yellow I believe has the best chance of 4-8 inches of snowfall; while areas outside of the yellow both north and south will be looking at 2-4 inches. The area encircled within blue will see freezing rain with some accumulations possible, while south of the green line you can expect mainly rain with only minor snowfall accumulations.

Winter Storm (Dec. 8-9)

The first true winter storm may end up slicing through the state of Iowa on Monday night and through Tuesday. Winter Storm Watches have been issued for several counties through both central and eastern Iowa where snowfall accumulations of 4-6 inches are currently forecasted. Other areas of the state will still likely see snowfall, where 2-4 inches is likely across western Iowa. The southeast part of the state looks to have a mix of precipitation, with some freezing rain/sleet possible before snow takes over and accumulates. Still a sensitive forecast with models being varying in location of the band of greatest snowfall, but it does seem to have a consensus in that it will be across some portion of the state of Iowa.

A few light snow showers may be across the state on Monday afternoon, but little accumulation is expected through the evening hours. By Monday night precipitation should expand across the entire state as a low pressure system in the central plains begins to wrap moisture around itself. The precip will be mainly snow for all but the southern third of the state where a rain/snow mix is possible through the nighttime hours. By Tuesday the cold air has pushed down through most of the state to allow for mainly snow. As the low moves off to the east, expect the snow to taper off in the northwest by Tuesday afternoon, and over the rest of the state by Wednesday morning. Although the snow is expected to stop, the strong winds of 20-30 mph will keep the snow blowing throughout the state to keep road conditions quite hazardous.

An update later tonight will provide a little more insight on where the strongest band of snowfall accumulation may setup, and exactly how much snow that band could create.

Wednesday, December 3, 2008

Dec. 3 Snow Accumulations

Snow amounts today weren't as heavy as anticipated, with the line of snow moving through quicker and being narrower than forecasts. Accumulations still caused plenty of travel hazards, as over a dozen accidents just around the Des Moines metro area occurred this morning, including a 9 vehicle accident just north of Des Moines. Storm total accumulations:

Ottumwa - 3.5"
Oskalooska - 3.0"
Rathbun - 2.0"
Knoxville - 2.0"
Des Moines - 1.6"
Lamoni - 1.0"
Ringsted - 1.0"
Waterloo - 0.8"
Mason City - 0.7"
Iowa Falls - 0.5"
Algona - 0.5"

Skies are beginning to clear, with just a few flurries being possible across northwest Iowa tonight with a weak disturbance. Temperatures tonight will be chilly, with northwest winds beginning to die down a bit they will be able to drop just a little further into the single digits over northeast Iowa and into the teens across the rest of the state. High temperatures on Thursday will be in the 20s throughout, with a few flurries still possible over mainly northwest Iowa. Thursday night lows will be even colder, with single digits over all but southwest Iowa! Friday's highs will warm up just ahead of our next storm system, ranging from the lower 20s to mid 30s from northeast to southwest. Friday night will see lows in the 20s for the most part, with mostly cloudy skies keeping them up compared to previous nights. Friday night snowfall should yield only a dusting to at most an inch, as moisture is fairly scarce at this point.

Into the weekend expect to see temperatures hovering in the 20s to near freezing, with lows in the single digits and teens on Saturday and then into the teens and 20s on Sunday night. This will lead into our next storm system entering the state on Sunday night and lasting into Monday. Snowfall is likely, although some mentions of sleet have also been thrown out in forecast discussions today. More details on this system in later updates...

For now, I'll leave this update tonight with a nice picture from earlier this summer of a Goldfinch that was taking a rest on a Lilac bush. A friendly reminder that the warmth is only 5 months away!!

Tuesday, December 2, 2008

More Snow!

A cold front has made its' way into and through northwest Iowa this evening, and will continue to move southeastward through the overnight hours. Behind this cold front will be another shot of cold air, and along with it a chance at a few hours of moderate to heavy snowfall. A large portion of the eastern two-thirds of the state is under a Winter Weather Advisory with 2-5 inches of snow being possible in those areas. Other parts of western Iowa will still see the snowfall, but their amounts should be less than 3 inches. For a graphical reference to the snowfall amounts, check out the latest Weather Story from Des Moines NWS.

Expect the snowfall to being just after midnight for northwest Iowa, with the heaviest amounts coming between 3 AM and 6 AM. This band of heavier snow should then work through a majority of central Iowa by Noon, and then into eastern Iowa during the afternoon hours. The snow may be heavy at times, and with northwest winds 15-25 mph expect some blowing snow to hamper driving conditions. Visibilities will easily drop below a mile, and with some slick conditions present after today's slight melting don't be surprised to see some hazardous travel.

Keep up on the latest road conditions across Iowa by using the Iowa Environmental Mesonet Roads page.

Look for the next update tomorrow afternoon with information on snow totals thus far and an updated temperature forecast as the cold air settles in!

Monday, December 1, 2008

Nov. 29 - 30 Snowfall Totals

Light to moderate snowfall continued for several hours from Saturday night through Sunday, leading to snowfall totals of over 6 inches in some portions of Iowa. Although much of western Iowa missed out on the snowfall, a band of heavier totals exists through central Iowa and into northeast Iowa. The image below is taken from the Iowa Environmental Mesonet and is the cooperative observers across the state and what they reported for total snow on the ground on Monday morning.

The next chance of snow for the state comes on Tuesday night into Wednesday, where a quick moving system will bring the potential for at least another dusty of snowfall across much of the state. More details on the potential for snow accumulations in tomorrows update!!