1/20/10 - KS/NE/IA Wintry Mix

[cstrunk]

I know we are all starting to get a little tired of winter weather after seeing several big storms already this season... but...

It looks like some areas are going to see some decent ice accumulations. Here in central Iowa, we're looking at .25-.5" of ice forecast.

Just wondering what other people (with more knowledge than I) had to say about this imminent weather threat?

 

[MatthewCarman]

Local news is saying up to half an inch of ice is possible in central Iowa with another ice storm possible by the weekend. I just want this weather to end. I don't want to miss any more school days then I have to.

 

[JSmith]

Who can be tired of winter weather?


I prefer winter weather!

 

[Nate Gillson]

Local news is saying up to half an inch of ice is possible in central Iowa with another ice storm possible by the weekend. I just want this weather to end. I don't want to miss any more school days then I have to.

I'm not as worried about the weekend storm as I am with this round of ZR beginning tommorow. This isn't a prolonged event but likely enough to dump a quarter to a half inch of ice across a good portion of Iowa. Thankfully the winds will be light and the temps will warm above freezing on Friday.

 

[Mike Hollingshead]

http://www.extremeinstability.com/

I put 4 images up on there from today as well as some words. We have over an inch of rime ice...again. Stuff doesn't want to come off either as I think the bit of freezing drizzle has it stuck there. Ice storm tonight is going to prove interesting, given the decent chance that stuff isn't falling off. It's already breaking small branches.

 

[MatthewCarman]

Local news met in central Iowa was saying winds could get up to 25 MPH and with half an inch of ice he was saying that could bring down power lines. If the storm get's that bad I would not be suprised if there is wide spread power outages.

 

[Nate Gillson]

Local news met in central Iowa was saying winds could get up to 25 MPH and with half an inch of ice he was saying that could bring down power lines. If the storm get's that bad I would not be suprised if there is wide spread power outages.

That could be bad but for the most part the winds are going to be light.

And DAMN mike h! I didn't know rime ice that thick could bring down tree branches.

EDIT: Oh yeah, there is a little rime ice here but less than a quarter inch thick.

 

[Jeff Duda]

Cobb output from the NAM at 18Z says 0.55" of ice in Des Moines, which is a little less than the 0.67" it was saying this morning. Although the Cobb output has been bouncing around lately. So who knows how much will actually fall. It depends on how much dry air works its way into the area by the time it starts.

 

[Bill Schintler]

Winter weather update - Iowa

Freezing rain will affect most of Iowa starting early Wednesday morning and continuing through Thursday morning. Locations generally south of I-80 in central Iowa will see a transition to “regularâ€￾ rain during the afternoon hours Wednesday, limiting Ice accumulations there. In eastern Iowa, the heaviest icing should be along US-30, where as much as 0.4 inched of ice is possible. In addition to obvious travel problems, this amount of ice may cause power outages. Looking ahead, another system will affect the area on Saturday, with early indications suggesting moderate-to-heavy rain as the primary precipitation type. Below is time of arrival and total ice accumulation for Wednesday’s event for specific locations in central and eastern IA:

Cedar Rapids, IA (Eastern IA Airport):
Fog and freezing drizzle overnight. Freezing rain will start at 6 AM Wednesday. Total ice accumulation: 0.30 inches.

Iowa City, IA:
Fog and freezing drizzle overnight. Freezing rain will start at 5:30 AM Wednesday. Total ice accumulation: 0.33 inches.

North Linn Co., IA (Paris and Coggon):
Fog and freezing drizzle overnight. Freezing rain will start at 6:30 AM Wednesday. Total ice accumulation: 0.28 inches.

Marengo, IA:
Fog and freezing drizzle overnight. Freezing rain will start at 5:30 AM Wednesday. Total ice accumulation: 0.34 inches.

Union, IA:
Fog and freezing drizzle overnight. Freezing rain will start at 6 AM Wednesday. Total ice accumulation: 0.30 inches.

Discussion:
UA analysis indicates an H5 ridge over the Upper-Midwest bounded by a low over the NRN Great Lakes and a developing trough over WA/OR. Over time, lift will increase as a lead H5 S/WV develops over NEB/KS within the left-exit region of an 80kt H5 speed max embedded within the SRN stream. In the mid-levels, moisture transport will increase overnight as a LLJ strengthens in advance of a developing H85 trough over NEB and KS. WAA and isentropic lift will increase between 00Z and 06Z. The H85 0C isotherm will push well N of IA by 06Z, 01/20/10; with temperatures along the I-80 corridor FCST to be between 3-4C by 12Z.

Timing of precipitation onset is a challenge as guidance is depicting too little moisture trapped beneath the inversion as compared to observations, and as such timing of onset will be adjusted one to two hours earlier S of US-30. This reasoning is supported by increasing fog and ST trends across SRN IA in association with theta-e advection in the H925 layer. Along and N of US-20, however, high-pressure over the Great Lakes will maintain a dry ELY SFC fetch. Visible satellite indicates clearing over WI and NERN IA in a zone of weak subsidence. Within this area, a deep cold and relatively dry layer in combination with evaporative cooling will support sleet for the first several hours of the event on Wednesday; with FCST soundings not showing a warm nose aloft much above 2 or 3 C. MDLs consistently support 0.3-0.4 inches of storm-total QPF across CNTRL IA, with the GFS most bullish and the ECMWF lighter then previous runs. Lesser QPF is noted in the N and E where forcing is offset by the dryer SFC AMS and is blocked along the back side of the H5 ridge.

Regarding precipitation type, the NAM maintains FZRA over the entire area for the duration of the event; while the GFS advertises a change over to RA S of I-80. The NAM likely has a more accurate handle of the temperature structure of the atmosphere. Supporting this is that weakening of the SFC low over time and a FCST motion E or even slightly SE, or along I-70 in MO. This should prevent significant warm entrainment into the storm while keeping SFC wet bulb temperatures below freezing for the duration of accumulating precipitation N of I-80. Additionally, the snowpack remains deep over the entire area. Looking at FCST soundings, NAM sounding valid for CID at 00Z, 01/21/00, indicates 31-32F at the SFC with the layer extending from 3 kft to over 7 kft above freezing.

Looking ahead, light precipitation will continue though early Thursday until dry air works into the mid-levels. A saturated AMS and easterly flow will remain in place near the SFC, resulting in periods of DZ and FRDZ with little or no additional accumulation. On Friday, a weak ridge in the mid-levels overspreads the area ahead of this weekend’s storm. This should dry out things in the LLVLs; however, cloudiness should prevail in the mid-levels.

- bill schintler
8:00 PM CST, 01/19/10

 

[Joel Wright]

Looks like a swath of decent ice accumulations over central Iowa tomorrow. Nice area of lift parks over central Iowa for much of the day. I think from just north of Des Moines to near Washington Iowa stands a good chance at seeing 1/2"-3/4" of glaze. The band of heaviest glazing will probably be relatively narrow due to much drier air eating at the northern edge of the precip, and warmer surface air chewing at the southern areas.

 

[Mike Hollingshead]

The thick rime ice was not knocked off by the rain. I measured 5/8th of an inch of ice on pieces of grass just above the snow that I know didn't have any rime ice on them.

Old image from yesterday for a reference since I have nothing online yet today after the ice last night.

The above is from yesterday, just the rime ice. That now has a big batch of lumpy 5/8th ice on it which doesn't even pull off. Trees snapping pretty frequently out here, with zero wind, just an infrequent 5-10 mph breeze, but mostly nothing.

The 12z NAM is pretty scary for this area and nw IA where radar estimates were higher with 1 inch plus there. Because it does not appear there's going to be much of any melting of this the rest of today. Maybe 33-34 tops for a while outside of towns, but seems mostly it will be 31-32. Nothing on trees here is melting at all yet. Then the NAM keeps the area below freezing on Thursday with fog and clouds. Friday isn't much different, low 30s for highs. Well then look what happens Friday night with the deepening surface low moving out on the plains. Strong easterly winds not going above freezing till sometime Saturday as those winds blow. This stuff could very well largely still be on the trees by then, given no sunshine and low 30s. Heck freezing drizzle with the fog could keep replacing any tiny bit of melting.

 

[MatthewCarman]

Someone told my dad his power was going out every 3 minutes and he lives in Des Moines. The storm has moved north of my area so if the winds stay light I should have no problems with the power. I am not hearing of any wide spread power outages thankfully.

 

[Nate Gillson]

OUCH

170
NWUS53 KDMX 201913
LSRDMX

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
112 PM CST WED JAN 20 2010

.TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON

.DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.

..REMARKS..

1257 PM FREEZING RAIN 4 E AUDUBON AIRPORT 41.70N 94.84W
01/20/2010 M0.75 INCH AUDUBON IA TRAINED SPOTTER

1257 PM ICE STORM 4 E AUDUBON AIRPORT 41.70N 94.84W
01/20/2010 AUDUBON IA TRAINED SPOTTER

MULTIPLE HUGE TREE LIMBS DOWN...GENERALLY 5 TO 6 INCHES
IN DIAMETER. ESTIMATED ABOUT 2 INCHES OF ICE/HOAR FROST
ACCUMULATED ON POWERLINES. 6 TO 7 POWER POLES DOWN ALONG
THE T-BONE HIGHWAY.

Audubon got hit hard from the ice storm on 12/23/2009.

 

[Mike Hollingshead]

Insanity around here. Over an inch of freezing rain accumulation around Dunlap-Soldier IA which was on top of rime ice, so you have a mound of ice on branches probably 3 inches diameter in areas. Long story. Can't explore off highways as it is extremely difficult to walk on flat gravel roads, let alone put a car on one. Back home and it's gotten worse if anything, zero melting on trees. Dense fog and freezing drizzle. Images later, trees popping like crazy now...with little to no wind.

Saw a lot of power trucks heading into that zone. There was NO melting of any of that in the country, not even those gravel roads. Once that wind picks up Friday/Friday night....anything left is toast. Things are toast in areas already anyway. Good thing is in towns it always seems a lot better ice wise. Like temps were extremely near 32 and just sneaking above in towns.

 

[MatthewCarman]

Wide spread power outages are now occuring across Central Iowa. Ch13 was showing the news when they went out of power near the end of their 30 minutes news cast and are now on a back up generater. Several places in Des Moines is without power. The gas station just a few blocks from where I live has no power and the lights at my house has been flickering. Thankfully we still have power. Lot's of small tree limbs down across the town but no big limbs has fallen.