So Many Variables to Consider

Let’s deal with tomorrow first…

In interpreting meteorological model data, the saying goes…the trend is your friend.  Over the last 24 hrs, clearly, the trend has been to strengthen the first surface low farther westward.  So much so, that this evening’s American models show the normally more reserved GFS joining the NAM in backing the 1/4″ liquid equivalent contour back to Raleigh.  And you all know the rule of thumb for converting liquid equivalent to snow… In general, use a 10:1 ratio (if it’s colder (combination of aloft and surface) use a higher ratio, which is rare in NC…or if it’s close to freezing  and/or mixed with sleet or graupel, then you’ll use a lower ratio)  So, if you believe this evening’s latest models then you think we could see a couple inches tomorrow.  I’m still not convinced.  Although, cold air is streaming in this evening, it seems unlikely to realize all of that QPF (meteorologist-ese for liquid equiv).  At this point, I would expect a dusting to an inch beginning early morning tomorrow.  Hopefully, not too many road problems unless we have a panic situation like 10 years ago!  Snow should increase in significance farther east and south where deeper moisture will be present.  Closer to the coast you’ll be fighting warmer air.  For the Triangle, let’s monitor the radar trends overnight and see if it looks like the significant precip shield will, in fact, extend this far west.


Dice-Dice-baby---4c9dfb5fa2f22_hiresLet’s talk about Wed nite into Thurs AM…

The thing about Wednesday is that with a good deal of sun during the day, surface temperatures could pop into the upper 40s.  If that is the case, a significant first portion of the snow that falls would be lost from accumulation totals to cooling the surface.  But…what if we have a more impressive showing tomorrow in snow cover?  In that case, we might not warm as much Wednesday afternoon.

At any rate, it seems that significant QPF will be realized over central NC overnite Wed/Thurs.  How much initial QPF will be lost is yet to understand.  There is ensemble agreement with >1/2″ of QPF for the event.  The disconcerting part of the equation is that, in particular, the GFS deterministic continues to track the low center east with only .1-.2″ of QPF for Raleigh.  In fact, this evening’s 0Z operational run of the GFS prints more QPF for RDU with tomorrow’s initial wave, rather than with the second storm.  A coup?   Maybe…but the problem is that the deterministic version of the GFS has been consistently tracking the low east of it’s ensemble suite mean.  Not good.

Thank you for reading to the end of my blah, blah, blah.  The bottom line is that there exists much uncertainty both Tuesday and late Wed.  And…the evidence suggests that there is potential for significant snowfall.  Tomorrow it could be a pretty snow shower, or…a accumulating snow to a 2″.  For Wed nite into Thurs AM, it could be as little as an inch, but as much 9.  So, let’s play it low key and we’ll talk tomorrow as to how this evolves.


Comments (8)

  1. 5:45 AM, February 24, 2015Lucy  / Reply

    My first activity this AM: check your blog.

  2. 5:55 AM, February 24, 2015Shelia  / Reply

    I look forward to this report whenever this is snow in the forecast. I believe it when you say it. Thanks for the work and thanks for sharing.

  3. 6:53 AM, February 24, 2015Suzanne  / Reply

    So, when do I hop on the HT electric cart for provisions???

  4. 7:27 AM, February 24, 2015Tina  / Reply

    I trust your reports as well.

  5. 8:05 AM, February 24, 2015Jonathan  / Reply

    I’m no expert, but it appears to be snowing now.

  6. 8:05 AM, February 24, 2015Lucy  / Reply

    When you say “tomorrow’ in this post, do you mean Feb. 24/ today? I finally realized (maybe?) that I think you posted this perhaps just after midnight. The “tomorrow” threw me off.

  7. 8:51 AM, February 24, 2015lsiffer  / Reply

    So…….what happened to just a dusting and no panic? LOL

  8. 3:52 PM, February 24, 2015Liz  / Reply

    What is graupel????
    Sounds like something yummy to eat!!

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