Saturday, January 29, 2011

Forecast Update

An extremely exciting and difficult forecast to put together.  While it is to early to narrow down the finer details, there are some larger trends that can be agreed upon.

Next week should see one of the most significant winter weather systems the Ohio Valley has seen in quite some time.  I know we talk about storm potential here and generally lean on toward even a bit of hype.  (Yeah, I admit to a bit of snow hype.)  Many times we are disappointed as the forecast models shift the storm in a different direction (or sometimes a completely different solution) or they cut the amount of QPF (precipitation) at the last minute.  Sometimes we just get unlucky and a dry slot or another problem kills Kokomo's snow totals.

While I cannot predict if bad luck will strike with this storm, I so think I can safety forecast we will not be missed and we will not get shorted with moisture.  (As I am typing this, the GGEM (Canadian Model) came us surpressed killing off the storm.  Ugh.)

Virtually all models have indicated strong transport is in place to pull moisture up from the Gulf of Mexico.  The GFS and Euro models show 1.25 to 1.5 inches of liquid for Kokomo.  While the NAM doesn't run more than 84 hours out, it also shows similar amounts are likely if one were to extrapolate what happens beyond the end of the run.

The models (NAM/Euro/GFS) also agree this will be widespread and it seems highly improbable that Kokomo or Indiana for that matter will be missed.  The entire Ohio Valley and Great Lake region will be effected by this system.

We can also see a tight baroclinic zone with this system.  This is where a tight temperature gradient exists and the surface pressure remain stable.  This is where the some of the heaviest snow will fall (and rapidly).  You can see the baroclinic zone on both the GFS and NAM. 

The significant difference and real problem with the forecast is the thermal profiles in the atmosphere.  Snow is produced when the column of air is below freezing all of the way down.  Even a tiny amount of surface warmth above freezing still results in snow.

Looking at the NAM (which matches the Euro), it shows a warm level producing sleet. 

The GFS on the other hand is below freezing at all levels and produces snow.

Yes, the 12z GFS which just ran this Saturday morning snows 23.3" of snow.  (I promise to pray for an early spring if this verifies.)  It ends up looking like this!  

At this point it is difficult to decided which solution to favor.  Both would be historic storms and I didn't even bring up the wind which will either produce blizzard like conditions or produce devastating consequences should the sleet or ice solution verify.  Very cold temps follow this system and days without electricity is likely should we not get snow.

I do think you will want to have your generator and snow blower both ready to go.  One will be needed. 

One thing we have on our side is the highest matching analog from a previous storm is the Valentine's Day Storm of 2007.  It was a prolific widespread snow producer for Howard County resulting in 16 to 18 inches of snow.  The sleet/ice problem was as close as 30 miles south but ended up not verifying here.  It looks remarkably similar to the GFS forecast. 

I will of course stay on top of everything as the weekend progresses and we get closer to the snow event.

Update: The Euro 12z run just came in and Kokomo gets 1.75"  of precipitation.  ALL SNOW!  Now the GFS and Euro are showing snow.

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