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December 2017 Long Range Disco


Bob Chill

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18 minutes ago, Bob Chill said:

GEFS is active w/ running waves up from the deep south but that's no surprise because the op looks the same. lol

What I like right now:

-Unanimous agreement that a significant cold front sweeps through this time next week

-Active flow behind the front

-Looking less likely that a PV hammer pounds everything into the GoM

-Strong baroclinic zone this time of year due to warm water and cold continental air clashing

-Decent support for blocking to slow down cold air from running away and cutters look less likely than usual

 

What I don't like right now:

-Storms running boundaries are generally narrow so snowfall would be narrow and the margin between rain or nothing at all is small

-Warm ocean temps would almost certainly cause problems with temps in the mid levels if something organized runs the coast

-Early Dec is hostile snow climo in these parts no matter what models show

-Until the initial frontal passage is modeled correctly (prob not until Mon-tues) models will be very jumpy and we rarely do well on the front side of flips to cold

There is one other small detail that I am not sure about.  On the GEFS, looking at 500mb,  from about hr300 onward is that a WAR?  I suppose that could be good if you are on the right side of it to keep things from escaping. I keep thinking WAR is bad but in this set up I am not sure.   

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18 minutes ago, BristowWx said:

There is one other small detail that I am not sure about.  On the GEFS, looking at 500mb,  from about hr300 onward is that a WAR?  I suppose that could be good if you are on the right side of it to keep things from escaping. I keep thinking WAR is bad but in this set up I am not sure.   

I suppose we have to look at it both ways. Have a big block and 50/50 looks great for big storms but it can also be a very dry pattern with squashed flow. WARs can be bad because they often correlate with active/progressive flow and east coast precipitation....but precipitation and rain are 2 different things....

The WAR was our best friend in 13-14/14-15 but it's been our enemy like a couple winters in the 90s where there was plenty of cold but it was never around when precip came through....lol

WARs will divide winners and losers and they can live really close together. My general opinion is a WAR in December is bad because the ocean is warm and the hemispheric cold pattern won't be nearly as strong as say Jan/Feb. OTOH- I'd much rather track multiple storms instead of one and done events surrounded by blue skies and boring weather for weeks on end.

In short....lol...IF the WAR flexes AND the cold is legit then heck yea I'll take my chances all day. Mixed events are fine. If the cold over overdone then chilly rain won't make any friends...haha

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Based on the GEFS, this looks like the schedule to me:

6-7: fropa with rain

8-9: coastal threat 

10-11: clipper?

12: coastal threat?

13+: overrunning scenario?

If you believe the 384 hour stuff, the final threat you mention *could* be a memorable event as the pattern relaxes somewhat. Probably another reload, but the NAO might be in transition temporarily and that transition can sometimes yield solid events. Long long way down the road though but taken verbatim past couple runs, that is the vibe Im getting for midmonth. I tink CAPE (?) had that period penciled in as well.
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1 minute ago, WxUSAF said:

Back to back fish storms on the euro. It’s a thread the needle but it’s not far off. Euro needs more upstream blocking to slow the trough down.

Yea, trough axis keeps all the goods east but it I liked seeing a potent vort dropping down after fropa. Some of our best clippers happen with digs like that. Get SLP popping in the lee of the apps down around the nc/sc border and we'd be in business. It's going to be a long week coming up. lol

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4 minutes ago, losetoa6 said:

Multiple vorts spinning within that flow ....I loved the run overall..Just minor tweaks . Many chances to score something...more energy diving thru the Dakota's at day 9/10 ... nice !

One thing the euro op delivers on is "winter appeal" for early Dec. Windy, cold, flurries, and all that stuff. So very close to a legit cold powder event too. Models are jumping but post fropa next week will almost certainly feel like winter and odds of seeing snow fall from the sky keep increasing. 

ETA: my guess is the 12z EPS is going to up the snow chances one way or another. Either higher mean snowfall or increased # of members with accum snow...or both. 

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EPS has trended like the GEFS with the WAR d10+. I actually kinda like it because both models show abundant cold nearby and overhead. The war should keep flow aligned along the coast instead of off the coast. The more we move forward in time the more it looks like an active period is on deck and less worry about cold/dry. I'll trade the risk of temp problems with multiple precip events and hug the fact that the last couple times we had a -epo/war combo it produced in prolific fashion. I'll prob be eating these words in a week....haha

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4 minutes ago, Bob Chill said:

EPS has trended like the GEFS with the WAR d10+. I actually kinda like it because both models show abundant cold nearby and overhead. The war should keep flow aligned along the coast instead of off the coast. The more we move forward in time the more it looks like an active period is on deck and less worry about cold/dry. I'll trade the risk of temp problems with multiple precip events and hug the fact that the last couple times we had a -epo/war combo it produced in prolific fashion. I'll prob be eating these words in a week....haha

My main concern is the Ian favorite of persistence - and it has been quite dry lately. Hopefully that changes with the pattern change. 

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