Weather Update 9:30 PM

A FREEZING RAIN ADVISORY remains in effect tonight and Thursday morning (purple color). The tan color is a WINTER WEATHER ADVISORY. Those counties will have some sleet mixed in making the roads slick there as well.

UPDATED at 9:55 PM: the winter weather advisory has been cancelled for Bremer, Butler and Franklin. 
Blog Graphic 1

The atmosphere near Decorah is setting up for when precipitation falls to be rain changing to freezing rain or freezing drizzle later tonight. There needs to be a cold layer of air above and below the warm layer. See image blow.

Apr 10 freezing-rain-profile

At 9 PM the surface temperatures are still slightly above freezing 34F or 1.1C. The temperatures higher up in the atmosphere are above freezing until about 500 mb.

Apr 10 Temps

This means as the ice crystal at 500 mb falls through part of the atmosphere above freezing it will melt…until it reaches the ground. The temperatures are forecast to reach the freezing point around 2-5 AM Thursday. At that time any precipitation that falls would be freezing rain or freezing drizzle. Surface temperatures are forecast to get above freezing around 9 or 10 AM Thursday.



Posted under Update

This post was written by Schnack on April 10, 2013

Wintry Weather Followed by More Rain

UPDATED at 4:40 PM

Tonight:  Areas along and north of a line from Charles City to Prairie du Chien, WI will have rain changing to freezing rain overnight. Areas south of that line will have rain. Low: 32-38. Wind: NE 15-25 mph.

Thursday: Cloudy with a 70% chance of rain/freezing rain north of the above mention line with rain south. Chance of rain expected for all of eastern Iowa during the afternoon. High: 36-45. Wind: NE 10-15 mph.

Thursday Night: Cloudy with rain changing to snow. Light accumulation trace-2″. Low: 29-31. Wind: NW 10-15 mph.

Friday: Cloudy with a snow showers in the morning. Any snow accumulation will be a trace to 2” with the 2” closer to the IA/MN state line. High: mid-upper 30s.

Saturday: Mostly cloudy. High: upper 40s.

Sunday: Mostly cloudy and windy (SE 15-25 mph) with a 60% chance of showers/storms. High: upper 50s.

Monday: Mostly cloudy with a 30% chance of showers. High: mid 50s.

Tuesday: Mostly cloudy with a 20% chance of showers. High: low 50s.

Wednesday: Mostly cloudy with at 20% chance of showers. High: near 50.

You probably will not like the forecast I am about to talk about since it does not include warm weather or any sunshine. Freezing rain and snow are not the most popular words this time of year.

The surface low is located near St. Louis with the upper level low is over Colorado and Nebraska (see map below).

Apr 10 Upper and Sfc Low
Rain continues to stream northeast along the surface front. The position of the surface low will not move much tonight. Another 0.50 to 1.5” of rain is possible through Thursday. A FLASH FLOOD WATCH remains in effect through Thursday.

Blog Graphic 2
Areas along and north of a line from Charles City to Prairie du Chien, WI will see rain change to freezing rain late tonight into Thursday morning. Sleet may mix in at times. The roads will be slick with ice accumulation less than 0.10”. The map below shows the chance of 0.10” of ice or more tonight.

Apr 10 Freezing Rain
A FREEZING RAIN ADVISORY (purple) is in effect tonight through Thursday morning for our northern counties A WINTER WEATHER ADVISORY (tan color) is in effect tonight through Thursday morning. The dark purple color on the map is an Ice Storm Warning and the pink is a Winter Storm Warning.

Blog Graphic 1
As temperatures warm up above freezing, by mid to late morning Thursday, any precipitation that falls will transition back to light rain. Areas south of Highway 20 tonight through Thursday will be just rain.

The upper level low will move east and be over Iowa Thursday night cooling the upper atmosphere to the surface changing the light rain to light snow/flurries. There is a chance of light snow accumulation by mid morning Friday. Areas north of Highway 20 will see 0.5 to 1 or 2”. Areas south of Highway 20 will see less of 0.5” if any accumulation. Here is the snow forecast from the WSI RPM model.

Apr 10 RPM Snow
Here is another look at the chance of 1”+ snow from the WPC for Thursday night.

Apr 10 1 inch snow
High pressure will keep the weather dry Saturday, but there will be more clouds than sun. High temperatures will remain below normal as with readings only in the 40s.

We are tracking another area of low pressure to impact us with showers and thunderstorms Sunday. A strong southeast wind ahead of the low will push highs into the upper 50s during the afternoon.

Monday through Wednesday will remain mostly cloudy with chances of showers each day. High temperatures during this stretch will be in the low 50s.


Posted under Forecast Discussion

This post was written by Schnack on April 10, 2013

24 Hour Rain Totals


7 AM Tuesday to 7 AM Wednesday

Location County Rain
Waterloo Black Hawk 1.01
Dubuque Dubuque 1.25
Cedar Rapids Linn 1.45
Iowa City Johnson 0.97
Ainsworth 7.4 N Washington 0.93
Anamosa 3SSW, IA Jones 1.73
BELLE PLAINE, IA Benton 1.20
BRIGHTON, IA Washington 0.99
CASCADE, IA Dubuque 1.60
Cedar Falls 1.4 SSE Black Hawk 0.95
Cedar Rapids 3.2 E Linn 1.25
Central City 6.7 W Linn 1.01
CLERMONT, IA Fayette 1.35
COGGON, IA Linn 1.52
CONRAD, IA Grundy 0.76
DE WITT, IA Clinton 0.58
Decorah 7.9 ENE Winneshiek 2.21
Dubuque #3, IA Dubuque 1.23
Dubuque L&D 11, IA Dubuque 1.37
ELKADER 6SSW, IA Clayton 1.84
ELMA, IA Howard 2.20
Ely 0.5 SE Linn 2.32
FAYETTE, IA Fayette 2.04
FULTON, IA Jackson 1.14
GUTTENBERG L & D 10, IA Clayton 1.26
IONIA 2W, IA Chickasaw 1.76
IOWA FALLS, IA Hardin 1.42
KESLEY 3 NNE, IA Butler 2.15
LADORA, IA Iowa 2.10
Latimer 1.9 NE Franklin 1.55
LOWDEN, IA Cedar 0.78
MANCHESTER NO. 2, IA Delaware 1.06
MAQUOKETA 4 W, IA Jackson 0.90
Marengo 2.6 SSW Iowa 1.40
Marion 1.2 NE Linn 1.39
Monona WWTP, IA Clayton 1.79
Monticello, IA Jones 1.68
NASHUA 2SW, IA Floyd 1.77
New Hampton 0.4 SW Chickasaw 2.23
NEW HAMPTON, IA Chickasaw 2.03
North Liberty 1.0 ENE Johnson 1.07
Oelwein 0.8 WNW Fayette 2.23
OSAGE , IA Mitchell 2.52
POSTVILLE, IA Allamakee 1.18
Quasqueton 1.8 S Buchanan 0.79
Solon 0.3 ESE Johnson 1.18
ST ANSGAR, IA Mitchell 2.90
TOLEDO 3 N, IA Tama 0.83
TRAER, IA Tama 1.05
TRIPOLI, IA Bremer 1.71
VINTON, IA Benton 0.86
VOLGA 1NE, IA Clayton 1.73
WASHINGTON, IA Washington 0.92
Waterloo 1.8 SSE Black Hawk 0.98
Waterloo 3.0 NNW Black Hawk 1.01
Williamsburg 6.2 SW Iowa 1.65


Posted under Precipitation Totals

This post was written by Schnack on April 10, 2013

April 10

TodayinWeatherHistoryFrom NWS
: A snow storm produced measurable snowfall across all of Iowa on April 9-12 with the heaviest snow falling across far southern Iowa on the 10th. Storm total accumulations included 18.8 inches at Lamoni, 21.0 inches at Centerville, and 22.0 inches at Bloomfield. The heavy, wet snow coated trees and power lines causing widespread damage and utility outages across southern Iowa. Numerous buildings suffered roof collapse from the weight of the snow in southeastern Appanoose and southwestern Davis counties, including a fire station and factory in Centerville. Structural engineers estimated that the weight of the snow on the factory roof was more than 30 pounds per square foot.

1973: Possibly the worst April blizzard on record in Iowa pounded the state from April 8-10. Snowfall totals of 20.3 inches at Belle Plaine and 19.2 inches at Dubuque set all-time storm total records at those locations. Total amounts of 16.0 inches were reported at Lansing and New Hampton, while Cedar Rapids received 14.5 inches, Iowa City 14.3 inches, and Des Moines 14.0 inches. At Des Moines 10.3 inches of their total fell just on the 9th, making it the snowiest April day on record at that location. Winds gusting to 65 mph or higher resulted in near zero visibility and blew the snow into drifts as deep as 16 feet closing most roads in the state.

1930: Very warm weather pushed the temperature all the way up to 96 F at Clarinda making this the earliest date of the year on which such a temperature has ever been recorded in Iowa. Other high temperatures included 95 F at Thurman, 94 F at Atlantic, 93 F at Burlington, Cedar Rapids, and Iowa City, and 92 F at Des Moines, Dubuque, and Keokuk. At many locations this remains the earliest date on record of temperatures in the 90s.

This Day in National/World Weather History …
 10 April 1929 → The former community of Sneed, AR in Jackson County was obliterated by an F5 (estimated) tornado. Twenty-three people were killed.
 10 April 1965 → An F4 tornado hit Arkansas killing 6 and injuring 250. The southeast and east parts of Conway were destroyed.
 10 April 1979 → In Wichita Falls, TX a massive tornado struck, killing 43 people and causing more $300 million in damage. Another tornado came down in Vernon, TX which killed eleven people.
 10 April 1996 → The world’s fastest measured surface wind (outside of a tornado) was recorded on Barrow island, Australia, in Tropical Cyclone Olivia. Winds reached a speed of 249mph.
 10 April 2001 → A devastating hailstorm swept along Interstate 70 from northeast Kansas to southwest Illinois, pounding the St. Louis area. It was one of the U.S.’s costliest hailstorms on record with a price tag of $2.4 billion.
 10 April 2009 → Several tornadoes tore across middle Tennessee, including an EF4 that struck the north side of Murfreesboro. The tornado was half a mile wide with multiple vortices and killed two people.


Posted under Weather History

This post was written by Schnack on April 10, 2013