Rhyuan Janssen
Hmm..my local weather stations are saying blizzard conditions and they expect blizz warnings... and that models are trending even stronger...will be interesting...
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12/22/07 FCST:IA/IL/MO/IN/WI/MN
- Thread starter Brandon Sullivan
- Start date
Jeff Piotrowski
EF3
Blizzard NC-OK/SC-NE/KS Saturday
The new 0Z WRF is much more aggressive with QPF .50-1.25 from END-PNC-EMP-MCI line with winds over 30+. I think parts of NC-OK/SC-NE/KS may need to be upgraded to a Blizzard Warning.
The new 0Z WRF is much more aggressive with QPF .50-1.25 from END-PNC-EMP-MCI line with winds over 30+. I think parts of NC-OK/SC-NE/KS may need to be upgraded to a Blizzard Warning.
Bill Schintler
EF4
Weekend winter storm - Eastern IA perspective
A well advertised winter storm will affect the Eastern Iowa area this weekend. Following are forecasts for specific locations followed by a forecast discussion.
Cedar Rapids:
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 4:30 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours. Gusty northwest winds to 35 mph will result in blowing snow. Total snowfall accumulation will be 3.0 inches before the snow ends during the early morning hours on Sunday.
Iowa City:
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 4:40 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours with thunder possible. Gusty northwest winds to 35 mph will result in blowing snow. Total snowfall accumulation will be 3.8 inches before the snow ends during the early morning hours on Sunday.
Quad Cities:
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 6:10 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours with thunder possible. Gusty northwest winds to 35 mph will result in blowing snow. Total snowfall accumulation will be 4.5 inches before the snow ends during the early morning hours on Sunday.
Marengo:
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 4:10 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours. Gusty northwest winds to 40 mph will result in blowing snow. Total snowfall accumulation will be 2.2 inches before the snow ends during the early morning hours on Sunday.
Paris and Coggon (north and northeast Linn CO.):
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 4:20 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours. Gusty northwest winds to 40 mph will result in blowing snow. Total snowfall accumulation will be 3.3 inches before the snow ends during the early morning hours on Sunday.
Synopsis:
WV imagery indicated energy diving S towards AZ along with a developing baroclinic leaf structure over ERN CO into NE. Meanwhile, a NRN-stream disturbance was moving rapidly to the SE towards ERN MT and ND. Over the next 36 hours, the SRN stream trough will become increasingly negatively-tilted while a couple of disturbances eject from the trough base and merge with the NRN stream ULVL system. The main challenge of the FCST lies in the details and timing of this phasing. Weak and disorganized SFC low pressure in the TX panhandle will shift slowly E and then NE towards WRN IL along a developing CF through 00Z Sunday, at which point rapid cyclogenesis will commence. Behind the CF, a surge of very cold air will race to the SE towards IA, with H85 temperatures falling to below -20C while raising concern about wind.
Discussion:
UA analysis and MDL initialization continue to indicate that MDLS are too warm and are underestimating the amount of mid-level CAA that should take place behind the system.
Given the very dynamic nature of this winter storm, elevated convection cannot be ruled out, especially between 04Z and 06Z on Sunday. MDLS have come into agreement with strength, location, and timing of key ULVL features. The latest trends also indicate a stronger SFC low that will track from S to N through NWRN IL while approaching bomb criteria. This increases confidence that ERN IA will see a significant precipitation event with about 70 percent of the QPF in the form of snow. Examining the evolution of the H85 low… Between 00Z, and 12Z, Sunday; the NAM keeps it in the DLH area and then shifts it slowly to the E towards the WRN Great Lakes as a secondary weaker low further S merges with it. The GFS, on the other hand, tends to redevelop a new low center further S along the trough in WRN IL. Other MDLS have solutions between these two extremes. In any event, the strongest forcing is not maximized at any specific location for more then about three hours, and SN will be maximized along a line parallel to and 90 miles NW of the H85 low track which will also be collocated with impressive H85 CAA. Taking a look at PROGGED H5 vorticity, MDL confidence remains low with the all important details as several compact vorticity bulls-eyes rotate through the area. Motion of these features and attendant UVM will be fast along the E side of the H5 trough. This all adds up to a short period of heavy snowfall rates along an axis from DVN NWRD into WI from 01Z-04Z. SN rates should be light for the remainder of the storm duration.
Regarding timing of changeover from RA to SN, the 1000-500mb thickness 540dm line should reach the Mississippi river by 00Z, leading to confidence that all but the very eastern tier of counties in IA should have changed over to SN. Wind should be a major factor, especially after midnight, as H85 temps fall to -20C, resulting in efficient downward momentum transfer of a 40-50kt NWRLY LLJ.
- bill
[FONT="]9:30 PM CST, 12/21/07[/FONT]
A well advertised winter storm will affect the Eastern Iowa area this weekend. Following are forecasts for specific locations followed by a forecast discussion.
Cedar Rapids:
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 4:30 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours. Gusty northwest winds to 35 mph will result in blowing snow. Total snowfall accumulation will be 3.0 inches before the snow ends during the early morning hours on Sunday.
Iowa City:
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 4:40 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours with thunder possible. Gusty northwest winds to 35 mph will result in blowing snow. Total snowfall accumulation will be 3.8 inches before the snow ends during the early morning hours on Sunday.
Quad Cities:
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 6:10 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours with thunder possible. Gusty northwest winds to 35 mph will result in blowing snow. Total snowfall accumulation will be 4.5 inches before the snow ends during the early morning hours on Sunday.
Marengo:
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 4:10 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours. Gusty northwest winds to 40 mph will result in blowing snow. Total snowfall accumulation will be 2.2 inches before the snow ends during the early morning hours on Sunday.
Paris and Coggon (north and northeast Linn CO.):
Expect periods of light rain or rain showers Saturday morning. Precipitation will change over to snow at 4:20 PM Saturday afternoon. During the change over, a brief period of freezing rain is likely however little ice accumulation is anticipated. Snowfall will become moderate to heavy for a few hours during the late evening hours. Gusty northwest winds to 40 mph will result in blowing snow. Total snowfall accumulation will be 3.3 inches before the snow ends during the early morning hours on Sunday.
Synopsis:
WV imagery indicated energy diving S towards AZ along with a developing baroclinic leaf structure over ERN CO into NE. Meanwhile, a NRN-stream disturbance was moving rapidly to the SE towards ERN MT and ND. Over the next 36 hours, the SRN stream trough will become increasingly negatively-tilted while a couple of disturbances eject from the trough base and merge with the NRN stream ULVL system. The main challenge of the FCST lies in the details and timing of this phasing. Weak and disorganized SFC low pressure in the TX panhandle will shift slowly E and then NE towards WRN IL along a developing CF through 00Z Sunday, at which point rapid cyclogenesis will commence. Behind the CF, a surge of very cold air will race to the SE towards IA, with H85 temperatures falling to below -20C while raising concern about wind.
Discussion:
UA analysis and MDL initialization continue to indicate that MDLS are too warm and are underestimating the amount of mid-level CAA that should take place behind the system.
Given the very dynamic nature of this winter storm, elevated convection cannot be ruled out, especially between 04Z and 06Z on Sunday. MDLS have come into agreement with strength, location, and timing of key ULVL features. The latest trends also indicate a stronger SFC low that will track from S to N through NWRN IL while approaching bomb criteria. This increases confidence that ERN IA will see a significant precipitation event with about 70 percent of the QPF in the form of snow. Examining the evolution of the H85 low… Between 00Z, and 12Z, Sunday; the NAM keeps it in the DLH area and then shifts it slowly to the E towards the WRN Great Lakes as a secondary weaker low further S merges with it. The GFS, on the other hand, tends to redevelop a new low center further S along the trough in WRN IL. Other MDLS have solutions between these two extremes. In any event, the strongest forcing is not maximized at any specific location for more then about three hours, and SN will be maximized along a line parallel to and 90 miles NW of the H85 low track which will also be collocated with impressive H85 CAA. Taking a look at PROGGED H5 vorticity, MDL confidence remains low with the all important details as several compact vorticity bulls-eyes rotate through the area. Motion of these features and attendant UVM will be fast along the E side of the H5 trough. This all adds up to a short period of heavy snowfall rates along an axis from DVN NWRD into WI from 01Z-04Z. SN rates should be light for the remainder of the storm duration.
Regarding timing of changeover from RA to SN, the 1000-500mb thickness 540dm line should reach the Mississippi river by 00Z, leading to confidence that all but the very eastern tier of counties in IA should have changed over to SN. Wind should be a major factor, especially after midnight, as H85 temps fall to -20C, resulting in efficient downward momentum transfer of a 40-50kt NWRLY LLJ.
- bill
[FONT="]9:30 PM CST, 12/21/07[/FONT]
Brandon Sullivan
EF5
It looks like the Oz Models have slowed down the system. Keeping precip over the area (IL/WI) through 6z-12z Sunday. Dont know how to take this, could mean cooler temps would be present during the heaviest precip.. Also, could mean the system will dig further south/east then proggd...
Interesting.. Hopefully morning packages will bring out some Warning Headlines
Interesting.. Hopefully morning packages will bring out some Warning Headlines
Rocky Rascovich
EF4
Convective snow bursts are occuring around Sumner Co. KS. as of 0900
reports of lightning with these echoes currently. My guess is that heavy snow/sleet with 2"+/hr occuring.
Rocky&family
reports of lightning with these echoes currently. My guess is that heavy snow/sleet with 2"+/hr occuring.
Rocky&family
Ben Prusia
EF4
Already some freezing rain falling with air temps around 30 degrees here in Gardner. TOP already upgraded some of their CWA to Winter Storm Warning, most likely expect EAX to do the same shortly.
Mike Umscheid
EF4
man, this does look pretty good for the I-35 corridor in KS... I'm actually in KC this weekend visiting fam for christmas, so I missed out on the mini-blizz back home in Dodge, looks like we may get more snow here in Overland Park than Dodge... looks like the intense deformation zone currently blitzing Wichita will slowly work eastward towards far east-central KS... a lot of warm frontogenetic pcpn now overspreading LWC and portions of KC metro with temps in the 31-32 range... NAM soundings suggest sleet here in Johnson county until about 2pm or so... then wherever that deformation band sets up with the heavy snow... a healthy dosing of 3-6" of wind driven snow :-D
afischer
EF4
Emporia reported thundersnow on a recent ob. No shortage of forcing with this sytem with intense DPVA, high-level divergence/difluence, 850-700mb frontogenetical forcing, and a developing trowal signature/elevated convective instability via the 12Z NAM and RUC. Moderate rain/sleet just began in a hurry outside my window as I type this.
Dick McGowan
EF5
Here in Lawrence, thunder every minute or so, with some bright flashes every once in awhile also. There were huge flakes about an hour ago, now it has switched back over to sleet, with some pea-sized or larger pieces, with a pretty strong north wind!
Ben Prusia
EF4
Moderate sleet continues to fall in the southern parts of Kansas City. Major highways out of the Kansas City area, including I-29 north of Dearborn and I-70 west of Topeka are closed. Whiteout conditions have been reported at numerous locations.
Right now, it appears heaviest snowfall to occur to the N and W of the KC Metro Area.
Right now, it appears heaviest snowfall to occur to the N and W of the KC Metro Area.
Jim Zandonai
Well most of the action in our region will be west of the MS river. Here the best we can hope for is about 2". But the biggest or most impressive part of this storm for us should be the wind field generated by the strong pressure gradient on Sunday..At least it should be rather impressive that way for us.
Brandon Sullivan
EF5
welp, DVN certainly wont have to eat crow. I already have .15 inches of ice! Roads are slick, and have reports of power lines down in the county west of me (Carthage,IL)
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Bill Schintler
EF4
NOW: winter WX in eastern IA
Very heavy snow and wind here in Iowa City, IA (11:45 PM) - mostly smaller flakes... Winds are probably gusting 30 mph or more with visibility of a few hundred feet. One lightning discharge noted about 15 minutes ago, the only one I've seen so far for the storm. I made a note that I heard thunder - often when there's a bright flash during an intense winter storm, it's a power line fault and not lightning. Radar trends indicate that the most intense precipitation band will shift east of the area over the next hour or so.
- bill
11:48 pm, 12/22
Very heavy snow and wind here in Iowa City, IA (11:45 PM) - mostly smaller flakes... Winds are probably gusting 30 mph or more with visibility of a few hundred feet. One lightning discharge noted about 15 minutes ago, the only one I've seen so far for the storm. I made a note that I heard thunder - often when there's a bright flash during an intense winter storm, it's a power line fault and not lightning. Radar trends indicate that the most intense precipitation band will shift east of the area over the next hour or so.
- bill
11:48 pm, 12/22
Joel Wright
EF5
Sleet and freezing rain (I'm still shocked this storm had this much ice!) has changed over to snow here in the last half hour. Full blown blizzard conditions at the moment. Winds have REALLY picked up in the last half hour, gusting to about 40mph already. It's only been snowing a short time and the ground has already become whitened again.
Edit: Moline officially reporting thundersnow and 1/4 mile visibility at 1am.
Edit: Moline officially reporting thundersnow and 1/4 mile visibility at 1am.
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Andrew Pritchard
EF5
Never figured I'd have a short range impromptu chase with the system. Severe warnings blanketing eastern Illinois now as a line of heavy showers and thunderstorms is apparently producing 60 mph wind gusts across central Illinois. I drove a quarter mile to the edge of town and parked it at a gas station and let it hit me. About what I'd expect, rain moving sideways. No thunder or anything in this area. Too bad the transition to snow wasn't faster, that would have been fun.
