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WxBlog / 20100219B

We might be in the sweet spot this time

HPC 3DAY >4We might actually be in the sweet spot for the next snowstorm brewing in the Plains, expected to affect our area from Sunday evening through Monday evening (21-22 February). The 2AM (ET) HPC 3-day forecast (shown at right) puts us on the edge of a 40% probability for >4". The NI WFO (IWX) has issued this Special Weather Statement:

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NORTHERN INDIANA
714 AM EST FRI FEB 19 2010

…POTENTIAL WINTER STORM SUNDAY NIGHT THROUGH MONDAY NIGHT…

A WINTER STORM WILL ORGANIZE OVER THE SOUTHERN PLAINS SATURDAY NIGHT AND MOVE THROUGH THE OHIO VALLEY SUNDAY NIGHT AND MONDAY… LIKELY CAUSING SNOW TO OVERSPREAD THIS AREA.

THE CURRENT FORECAST TRACK OF THIS LOW PRESSURE SYSTEM SUGGESTS THAT PORTIONS OF THE AREA COULD RECEIVE IN EXCESS OF 6 INCHES OF SNOW BETWEEN SUNDAY NIGHT AND MONDAY NIGHT. HOWEVER… THERE REMAINS MUCH UNCERTAINTY WITH RESPECT TO THE TRACK OF THIS SYSTEM. A FARTHER NORTH TRACK WOULD RESULT IN THE SNOW CHANGING TO RAIN OR FREEZING RAIN IN THIS AREA… WHILE A FARTHER SOUTH TRACK WOULD RESULT IN ALL SNOW ACROSS THIS AREA… BUT LESS ACCUMULATION.

REGARDLESS OF THE FINAL TRACK AND SNOWFALL AMOUNTS…THERE IS THE POTENTIAL FOR TRAVEL TO BE IMPACTED EARLY NEXT WEEK. STAY TUNED TO NOAA WEATHER RADIO AND LOCAL MEDIA OUTLETS FOR THE LATEST INFORMATION ON THIS POTENTIAL WINTER STORM.

The meteorologists at IWX are forecasting about an inch of snow out ahead of this system, from about 1AM Saturday through 7AM Sunday. The winter storm then begins about 7PM Sunday, and through 7PM Monday they expect 3.8" snow (LWE 0.38"). Snow continues after 7PM Monday but they have no specific forecasted amount that far out.

LWE forecastThe IWX folks were working off the 06Z NAM; today's 12Z NAM forecast (from twisterdata.com) shows even more potential out of this storm. From 03Z on the 22nd (2200 ET Sunday) through 00Z on the 23rd (1900 ET Monday), the NAM shows us getting 0.93" LWE. The temperature hovers at or just below freezing in the lower 150mb of the atmosphere; it looks like we may actually get cold rain for a while (which would totally screw things up). However, if we were to manage to get all snow, we would get about 9".

The animation at left shows 3 hour accumulated precipitation covering the full 84 hours of the 12Z NAM forecast (from 7AM today through 7PM Monday). The last frame of the animation (which lasts longer) shows the 24 hour accumulated precipitation for hour 84 (i.e., the amount of precipitation between 7PM Sunday and 7PM Monday). These are LWE (liquid water equivalent); at the forecasted temperatures, multiply by 10 to estimate snowfall.

I'm not holding my breath; I'll believe it when I have to shovel it.

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awc 2010-02-19 12:15:36
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