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2/19 Weekend Threat


am19psu

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850s in the -4 range...surface upper 30 to low 40s

Not bad, it would be horrible to get an all-snow event at the expense of the northern part of our area. Rates will need to be quite high to overcome those torchy surface temps; things would probably turn out better for all parties if the low was more developed and further north.

Right now, I'm not ready to give up just because the 12z euro came south.

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Interesting to note the obvious trend of a stronger 50/50. There has been much said about how the lack of phase between the northern stream and southern stream energy doesn't "tug" our Miller A up the coast, but the northern vort also acts to invigorate the 50/50 low, further dampening the height field off the NE and northern mid-Atlantic coast.

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12Z Euro laden with initialization errors per AFD out of NC from the MA thread. Take this run with a grain of salt and expect changes at 0Z.

"...12Z GFS AND 00Z ECMWF IN DECENT AGREEMENT

REGARDING SYSTEM FOR SAT-SUN WITH THE SLOWER NAM POORLY INITIALZED

AND CONSIDERED AN OUTLIER. THE 12 ECMWF ALSO INITLIALZED POORLY SO

IT WAS NOT USED."

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12Z Euro laden with initialization errors per AFD out of NC from the MA thread. Take this run with a grain of salt and expect changes at 0Z.

"...12Z GFS AND 00Z ECMWF IN DECENT AGREEMENT

REGARDING SYSTEM FOR SAT-SUN WITH THE SLOWER NAM POORLY INITIALZED

AND CONSIDERED AN OUTLIER. THE 12 ECMWF ALSO INITLIALZED POORLY SO

IT WAS NOT USED."

This was the British Colombian Short Wave. Using the Boxing Day timing of modeling corroboration as a guide, to get to the same point when those models came together we'd be talking about the 00z run on Saturday. So its too early.

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It wasn't as flat exiting NC as the op was, but that really is a moot point with the overall depiction.

Still a weird spread at 500mb, at hr 72. Seems like some of the models are a bit of a disagreement with how they handle the nrn stream. However, the mean didn't look all that bizarre to me. Looked sensible.

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Adam, anything on the euro ens?

Basically the same thing as 0z. Precip was a little farther south, as the theme has gone for this set of runs. There's still maybe 5-6 inland runners in there. In terms of QPF, .1-.25 went for the northern half of our area, .25-.5 for the southern half.

I'm still sticking with my 1-3 call for PHL at this time.

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Basically the same thing as 0z. Precip was a little farther south, as the theme has gone for this set of runs. There's still maybe 5-6 inland runners in there. In terms of QPF, .1-.25 went for the northern half of our area, .25-.5 for the southern half.

I'm still sticking with my 1-3 call for PHL at this time.

A very good call IMO.

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12Z Euro laden with initialization errors per AFD out of NC from the MA thread. Take this run with a grain of salt and expect changes at 0Z.

"...12Z GFS AND 00Z ECMWF IN DECENT AGREEMENT

REGARDING SYSTEM FOR SAT-SUN WITH THE SLOWER NAM POORLY INITIALZED

AND CONSIDERED AN OUTLIER. THE 12 ECMWF ALSO INITLIALZED POORLY SO

IT WAS NOT USED."

As Wes and DTK point out from the MA forum, there is a lot of subjectivity with regard to what is a "poor initialization" so I wouldnt be so quick to dismiss the Euro, especially since the ensembles are similar.

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Basically the same thing as 0z. Precip was a little farther south, as the theme has gone for this set of runs. There's still maybe 5-6 inland runners in there. In terms of QPF, .1-.25 went for the northern half of our area, .25-.5 for the southern half.

I'm still sticking with my 1-3 call for PHL at this time.

It does seem that they (the Euro ensembles) have been pretty steady for at least three sounding runs or so. I'm guessing that the freebie site's purple haze is being caused by (what I think) those rogue inland runners. Even the gefs clustering is fairly tight.

post-623-0-39307600-1329425927.png

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NCEP Operational Status Message

Thu Feb 16 20:33:07 2012 GMT

NOUS42 KWNO 162031

ADMNFD

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE

NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD

2028Z THU FEB 16 2012

THE 18Z NAM POST PROCESSING BEGAN RUNNING LATE AFTER FORECAST HOUR

09...DELAYS HAVE GROWN TO OVER 20 MINUTES AT THIS TIME.

PRODUCTION ANALYSTS ARE CURRENTLY LOOKING INTO THE ISSUE. WE

REGRET ANY INCONVENIENCE THIS MAY CAUSE...

$$

OREILLY/SDM/NCO/NCEP

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What a nightmare of a forecast...

20120218-19_MAsnowInitial.png

If I didn't already say I was going to put out a snow map today I would probably have waited until tomorrow for a first call. As it is, I might do a second update before my final call on Saturday if the forecast seems to converge well over the next 24 hours.

As has been the case all winter, the boundary layer temperatures are going to be a big issue with this event. Most (if not all) of the snow will be on the back end of the system, which doesn't help matters, either. The latest models would suggest pulling the QPF further south and maybe some of the snow totals along with it, but it wouldn't be much further south than what I currently have depicted.

For the Philly metro, I don't think the snow rates will be good enough for long enough to get at least an inch out of this, but a coating to an inch is possible (if not likely).

-----

For those of you who aren't familiar with my snow forecasts, I do make full verification maps and post them on Amwx as well as my blog - http://madusweather.com/ ...I haven't been doing as well as I would like so far this winter, so take the map for what it's worth.

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As Wes and DTK point out from the MA forum, there is a lot of subjectivity with regard to what is a "poor initialization" so I wouldnt be so quick to dismiss the Euro, especially since the ensembles are similar.

We've seen this cut both ways. I would think this particular short wave should be better sampled now that it will be inland for tonight's 00z run. I get confused with all of the regional threads, but someone did say that this reminded him of 97-98 in that there was not alot of surface cold air around.

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We've seen this cut both ways. I would think this particular short wave should be better sampled now that it will be inland for tonight's 00z run. I get confused with all of the regional threads, but someone did say that this reminded him of 97-98 in that there was not alot of surface cold air around.

Tony. that might have been me. It's crazy that back then we were in a mega nino and now we're in a nina but warm is warm and lows that track up the coast with little in the way of cold are *^*& to forecast.

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Well, that's at least 4 GFS runs in a row that have trended south and slower.

Yup, at this point there is no model out there giving PHL area any significant snowfall....I know some people will rely on the "north trend", but at this point I'd say odds strongly favor little or no snowfall with this storm in the area.

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Yup, at this point there is no model out there giving PHL area any significant snowfall....I know some people will rely on the "north trend", but at this point I'd say odds strongly favor little or no snowfall with this storm in the area.

It definitely seems that way. I certainly wouldn't rule out a shift back north... but like you said, the odds don't seem to favor it.

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